The purposes of this study were to assess unilateral and bilateral vertical jump performance
characteristics, and to compare the vertical ground reaction force characteristics of the impulse and landing
phase of a vertical jump between the dominant and non-dominant leg in soccer players.
Differences in strength and speed demands between 4v4 and 8v8 SSGFernando Farias
Small-sided games (SSGs) have been extensively used in training
footballers worldwide and have shown very good efficacy in
improving player performance (Hill-Haas, Dawson, Impellizzeri,
& Coutts, 2011). As an example, it has been shown that the
technical performance (Owen, Wong del, McKenna, & Dellal,
2011) and physical performance (Chaouachi et al., 2014; Dellal,
Varliette, Owen, Chirico, & Pialoux, 2012) of footballers can be
enhanced using SSG-based football training programmes.
In the last two decades, extensive research has been pub-
lished on physical and physiological response during SSGs in
football (for refs, see Halouani, Chtourou, Gabbett, Chaouachi,
& Chamari, 2014). It was found that the time-motion charac-
teristics of SSGs could vary greatly depending on certain
structural (e.g., pitch size, number of players, type and number
of goals) and rule (e.g., number of ball touches) constraints.
For example, it was observed that higher maximum speeds are
reached during SSGs played on bigger pitches (Casamichana &
Castellano, 2010). Furthermore, heart rate (HR) and lactate
concentrations were shown to be sensitive to structural and
rule changes in SSGs.
Epidemiological studies have consistently shown hamstring
strain injuries (HSIs) to have a high prevalence rate in many
sports, such as sprinting (11%; Lysholm & Wiklander, 1987),
Australian Rules Football (16–23%; Orchard, 2001; Orchard,
Marsden, Lord, & Garlick, 1997) and football (12–14%:
Ekstrand, Hagglund, & Walden, 2011; Hawkins, Hulse,
Wilkinson, Hodson, & Gibson, 2001). The epidemiology and
aetiology of HSI in football has received extensive attention in
the scientific literature (Ekstrand et al., 2011; Woods et al., 2004),
given the economic burden associated with professional
players missing training and competitive fixtures (Woods,
Hawkins, Hulse, & Hodson, 2002). b
Hamstring injuries are among the most com-
mon non-contact injuries in sports. The Nordic hamstring
(NH) exercise has been shown to decrease risk by
increasing eccentric hamstring strength.
Effects of Velocity Loss During Resistance Training on Performance in Profess...Fernando Farias
To analyze the effects of two resistance training (RT) programs that used the same relative loading but different repetition volume, using the velocity loss during the set as the independent variable: 15% (VL15) vs. 30% (VL30). Methods: Sixteen professional soccer players with RT experience (age 23.8 ± 3.5 years, body mass 75.5 ± 8.6 kg) were randomly assigned to two groups: VL15 (n = 8) or VL30 (n = 8) that followed a 6-week (18 sessions) velocity-based squat training program. Repetition velocity was monitored in all sessions. Assessments performed before (Pre) and after training (Post) included: estimated one- repetition maximum (1RM) and change in average mean propulsive velocity (AMPV) against absolute loads common to Pre and Post tests; countermovement jump (CMJ); 30-m sprint (T30); and Yo-yo intermittent recovery test (YYIRT).
Nossos dados sugerem que um macrociclo com ênfase na capacidade técnica e tática foi capaz de promover aumentos no desempenho físico e tático de jovens jogadores de futebol em situações reais de disputa. Assim, a distribuição das cargas de treinamento utilizadas neste estudo, além de possibilitar uma formação mais específica e contextual, proporcionou um aumento da intensidade do jogo no final da temporada, variável diretamente relacionada ao resultado do jogo (17). Além disso, verificou-se que o protocolo de treinamento causou reduções nos marcadores de danos musculares, revelando um estímulo benéfico para o sistema muscular, o que pode contribuir para a prevenção de lesões por sobreentrenamento ao longo da temporada. Apesar da importância bem documentada da avaliação de parâmetros sangüíneos (ie, marcadores de dano) durante a prática de futebol (3, 4, 23, 29), verificamos que a redução relacionada foi associada com maior taxa de trabalho durante o jogo, Através de um treinamento técnico-tático de periodização, mostrando a importância do monitoramento desses parâmetros em longo prazo.
Training Load and Fatigue Marker Associations with Injury and IllnessFernando Farias
This paper provides a comprehensive review of the litera-
ture that has reported the monitoring of longitudinal
training load and fatigue and its relationship with injury
and illness. The current findings highlight disparity in the
terms used to define training load, fatigue, injury and ill-
ness, as well as a lack of investigation of fatigue and
training load interactions. Key stages of training and
competition where the athlete is at an increased risk of
injury/illness risk were identified. These included periods
of training load intensification, accumulation of training
load and acute change in load. Modifying training load
during these periods may help reduce the potential for
injury and illness.
Acute effect of different combined stretching methodsFernando Farias
The purpose of this study was to investigate the acute effect of different stretching methods, during a warm-up,
on the acceleration and speed of soccer players. The acceleration performance of 20 collegiate soccer players (body height:
177.25 ± 5.31 cm; body mass: 65.10 ± 5.62 kg; age: 16.85 ± 0.87 years; BMI: 20.70 ± 5.54; experience: 8.46 ± 1.49
years) was evaluated after different warm-up procedures, using 10 and 20 m tests. Subjects performed five types of a
warm-up: static, dynamic, combined static + dynamic, combined dynamic + static, and no-stretching. Subjects were
divided into five groups. Each group performed five different warm-up protocols in five non-consecutive days. The
warm-up protocol used for each group was randomly assigned. The protocols consisted of 4 min jogging, a 1 min
stretching program (except for the no-stretching protocol), and 2 min rest periods, followed by the 10 and 20 m sprint
test, on the same day. The current findings showed significant differences in the 10 and 20 m tests after dynamic
stretching compared with static, combined, and no-stretching protocols. There were also significant differences between
the combined stretching compared with static and no-stretching protocols. We concluded that soccer players performed
better with respect to acceleration and speed, after dynamic and combined stretching, as they were able to produce more
force for a faster execution.
Sprint running acceleration is a key feature of physical performance in team sports, and recent
literature shows that the ability to generate large magnitudes of horizontal ground reaction force
and mechanical effectiveness of force application are paramount. We tested the hypothesis that
very-heavy loaded sled sprint training would induce an improvement in horizontal force
production, via an increased effectiveness of application. Training-induced changes in sprint
performance and mechanical outputs were computed using a field method based on velocity-
time data, before and after an 8-week protocol (16 sessions of 10x20-m sprints). 16 male
amateur soccer players were assigned to either a very-heavy sled (80% body-mass sled load)
or a control group (unresisted sprints). The main outcome of this pilot study is that very-heavy
sled resisted sprint training, using much greater loads than traditionally recommended, clearly
increased maximal horizontal force production compared to standard unloaded sprint training
(effect size of 0.80 vs 0.20 for controls, unclear between-group difference) and mechanical
effectiveness (i.e. more horizontally applied force; effect size of 0.95 vs -0.11, moderate
between-group difference)
Differences in strength and speed demands between 4v4 and 8v8 SSGFernando Farias
Small-sided games (SSGs) have been extensively used in training
footballers worldwide and have shown very good efficacy in
improving player performance (Hill-Haas, Dawson, Impellizzeri,
& Coutts, 2011). As an example, it has been shown that the
technical performance (Owen, Wong del, McKenna, & Dellal,
2011) and physical performance (Chaouachi et al., 2014; Dellal,
Varliette, Owen, Chirico, & Pialoux, 2012) of footballers can be
enhanced using SSG-based football training programmes.
In the last two decades, extensive research has been pub-
lished on physical and physiological response during SSGs in
football (for refs, see Halouani, Chtourou, Gabbett, Chaouachi,
& Chamari, 2014). It was found that the time-motion charac-
teristics of SSGs could vary greatly depending on certain
structural (e.g., pitch size, number of players, type and number
of goals) and rule (e.g., number of ball touches) constraints.
For example, it was observed that higher maximum speeds are
reached during SSGs played on bigger pitches (Casamichana &
Castellano, 2010). Furthermore, heart rate (HR) and lactate
concentrations were shown to be sensitive to structural and
rule changes in SSGs.
Epidemiological studies have consistently shown hamstring
strain injuries (HSIs) to have a high prevalence rate in many
sports, such as sprinting (11%; Lysholm & Wiklander, 1987),
Australian Rules Football (16–23%; Orchard, 2001; Orchard,
Marsden, Lord, & Garlick, 1997) and football (12–14%:
Ekstrand, Hagglund, & Walden, 2011; Hawkins, Hulse,
Wilkinson, Hodson, & Gibson, 2001). The epidemiology and
aetiology of HSI in football has received extensive attention in
the scientific literature (Ekstrand et al., 2011; Woods et al., 2004),
given the economic burden associated with professional
players missing training and competitive fixtures (Woods,
Hawkins, Hulse, & Hodson, 2002). b
Hamstring injuries are among the most com-
mon non-contact injuries in sports. The Nordic hamstring
(NH) exercise has been shown to decrease risk by
increasing eccentric hamstring strength.
Effects of Velocity Loss During Resistance Training on Performance in Profess...Fernando Farias
To analyze the effects of two resistance training (RT) programs that used the same relative loading but different repetition volume, using the velocity loss during the set as the independent variable: 15% (VL15) vs. 30% (VL30). Methods: Sixteen professional soccer players with RT experience (age 23.8 ± 3.5 years, body mass 75.5 ± 8.6 kg) were randomly assigned to two groups: VL15 (n = 8) or VL30 (n = 8) that followed a 6-week (18 sessions) velocity-based squat training program. Repetition velocity was monitored in all sessions. Assessments performed before (Pre) and after training (Post) included: estimated one- repetition maximum (1RM) and change in average mean propulsive velocity (AMPV) against absolute loads common to Pre and Post tests; countermovement jump (CMJ); 30-m sprint (T30); and Yo-yo intermittent recovery test (YYIRT).
Nossos dados sugerem que um macrociclo com ênfase na capacidade técnica e tática foi capaz de promover aumentos no desempenho físico e tático de jovens jogadores de futebol em situações reais de disputa. Assim, a distribuição das cargas de treinamento utilizadas neste estudo, além de possibilitar uma formação mais específica e contextual, proporcionou um aumento da intensidade do jogo no final da temporada, variável diretamente relacionada ao resultado do jogo (17). Além disso, verificou-se que o protocolo de treinamento causou reduções nos marcadores de danos musculares, revelando um estímulo benéfico para o sistema muscular, o que pode contribuir para a prevenção de lesões por sobreentrenamento ao longo da temporada. Apesar da importância bem documentada da avaliação de parâmetros sangüíneos (ie, marcadores de dano) durante a prática de futebol (3, 4, 23, 29), verificamos que a redução relacionada foi associada com maior taxa de trabalho durante o jogo, Através de um treinamento técnico-tático de periodização, mostrando a importância do monitoramento desses parâmetros em longo prazo.
Training Load and Fatigue Marker Associations with Injury and IllnessFernando Farias
This paper provides a comprehensive review of the litera-
ture that has reported the monitoring of longitudinal
training load and fatigue and its relationship with injury
and illness. The current findings highlight disparity in the
terms used to define training load, fatigue, injury and ill-
ness, as well as a lack of investigation of fatigue and
training load interactions. Key stages of training and
competition where the athlete is at an increased risk of
injury/illness risk were identified. These included periods
of training load intensification, accumulation of training
load and acute change in load. Modifying training load
during these periods may help reduce the potential for
injury and illness.
Acute effect of different combined stretching methodsFernando Farias
The purpose of this study was to investigate the acute effect of different stretching methods, during a warm-up,
on the acceleration and speed of soccer players. The acceleration performance of 20 collegiate soccer players (body height:
177.25 ± 5.31 cm; body mass: 65.10 ± 5.62 kg; age: 16.85 ± 0.87 years; BMI: 20.70 ± 5.54; experience: 8.46 ± 1.49
years) was evaluated after different warm-up procedures, using 10 and 20 m tests. Subjects performed five types of a
warm-up: static, dynamic, combined static + dynamic, combined dynamic + static, and no-stretching. Subjects were
divided into five groups. Each group performed five different warm-up protocols in five non-consecutive days. The
warm-up protocol used for each group was randomly assigned. The protocols consisted of 4 min jogging, a 1 min
stretching program (except for the no-stretching protocol), and 2 min rest periods, followed by the 10 and 20 m sprint
test, on the same day. The current findings showed significant differences in the 10 and 20 m tests after dynamic
stretching compared with static, combined, and no-stretching protocols. There were also significant differences between
the combined stretching compared with static and no-stretching protocols. We concluded that soccer players performed
better with respect to acceleration and speed, after dynamic and combined stretching, as they were able to produce more
force for a faster execution.
Sprint running acceleration is a key feature of physical performance in team sports, and recent
literature shows that the ability to generate large magnitudes of horizontal ground reaction force
and mechanical effectiveness of force application are paramount. We tested the hypothesis that
very-heavy loaded sled sprint training would induce an improvement in horizontal force
production, via an increased effectiveness of application. Training-induced changes in sprint
performance and mechanical outputs were computed using a field method based on velocity-
time data, before and after an 8-week protocol (16 sessions of 10x20-m sprints). 16 male
amateur soccer players were assigned to either a very-heavy sled (80% body-mass sled load)
or a control group (unresisted sprints). The main outcome of this pilot study is that very-heavy
sled resisted sprint training, using much greater loads than traditionally recommended, clearly
increased maximal horizontal force production compared to standard unloaded sprint training
(effect size of 0.80 vs 0.20 for controls, unclear between-group difference) and mechanical
effectiveness (i.e. more horizontally applied force; effect size of 0.95 vs -0.11, moderate
between-group difference)
Maximal sprinting speed of elite soccer playersFernando Farias
Current findings might help individuals involved within the physical preparation of players (e.g. technical coaches, fitness coaches, and sport science staff) when developing training programs and training sessions in line with the playing positions, and with the levels of high speed running targeted to reach during specific training drills like sided-games.
Indeed, the closer to match-play situations regarding the rules with goals, goalkeepers, the larger pitch sizes and greater number of players involved, the higher sprinting speed running players would reach during sided-games. However, coaches are advised to add specific speed drills to sided-games in order to elicit a stimulus of high-speed running high enough to prepare players for competition.
To examine the acute effects of generic (Running Drills, RD) and specific (Small-
Sided Games, SSG) Long Sprint Ability (LSA) drills on internal and external load of male
soccer-players. Methods: Fourteen academy-level soccer-players (mean±SD; age 17.6±0.61
years, height 1.81±0.63 m, body-mass 69.53±4.65 kg) performed four 30s LSA bouts for
maintenance (work:rest, 1:2) and production (1:5) with RD and SSG drills. Players’ external-
load was tracked with GPS technology (20Hz) and heart-rate (HR), blood-lactate
concentrations (BLc) and rate of perceived exertion (RPE) were used to characterize players’
internal-load. Individual peak BLc was assessed with a 30s all-out test on a non-motorized
treadmill (NMT). Results: Compared to SSGs the RDs had a greater effect on external-load
and BLc (large and small, respectively). During SSGs players covered more distance with
high-intensity decelerations (moderate-to-small). Muscular-RPE was higher (small-to-large)
in RD than in SSG. The production mode exerted a moderate effect on BLc while the
maintenance condition elicited higher cardiovascular effects (small-to-large). Conclusion:
The results of this study showed the superiority of generic over specific drills in inducing
LSA related physiological responses. In this regard production RD showed the higher post-
exercise BLc. Interestingly, individual peak blood-lactate responses were found after the
NMT 30s all-out test, suggesting this drill as a valid option to RD bouts. The practical
physiological diversity among the generic and specific LSA drills here considered, enable
fitness trainers to modulate prescription of RD and SSG drills for LSA according to training
schedule.
Short inter-set rest blunts resistance exercise-inducedFernando Farias
Manipulating the rest-recovery interval between sets of resistance exercise may influence
training-induced muscle remodelling. The aim of this study was to determine the acute muscle
anabolic response to resistance exercise performed with short or long inter-set rest intervals.
In a study with a parallel-group design, 16 males completed four sets of bilateral leg-press and
knee-extension exercise at 75% of one-repetition maximum to momentary muscular failure,
followed by ingestion of 25 g of whey protein. Resistance exercise sets were interspersed by
1 min (n = 8) or 5 min of passive rest (n = 8). Muscle biopsies were obtained at rest, 0, 4, 24
and 28 h postexercise during a primed continuous infusion of l-[ring-13C6]phenylalanine to
determine myofibrillar protein synthesis and intracellular signalling.
The effects of self-myofascial release using a foam roll or roller massager on joint range of motion, muscle recovery, and performance: a systematic review
Melhorar ou até mesmo manter o desempenho atlético em jogadores de esportes de equipe competitivos durante o longo período da temporada é um dos maiores desafios para qualquer treinador comprometido. Tempo muito limitado está disponível entre as partidas semanais para introduzir sessões intensivas de treinamento de força e poder, com uma freqüência normal de 1-2 unidades por semana. Este fato estimula a busca de métodos de treinamento mais eficientes capazes de melhorar uma ampla variedade de habilidades funcionais, evitando ao mesmo tempo os efeitos de fadiga.
Os resultados atuais indicaram que a ocorrência de lesões de isquiotibiais podem estar associadas a uma mudança hierárquica na distribuição da atividade metabólica dentro do complexo muscular do isquiotibial após o trabalho excêntrico em que o Semitendinoso provavelmente deveria tomar a parte principal, seguido pelo BÍceps Femural e Semimembranoso. Quando o BF aumenta sua contribuição e é ativado em uma extensão proporcionalmente maior, o risco de sofrer uma lesão do isquiotibial pode aumentar substancialmente.
Hamstring strain prevention in elite soccer playersFernando Farias
Hamstring strains are among the most
common injury in sport and are most
often observed in sports that involve
sprinting, turning, and jumping
(8,38,63). The prevalence of hamstring
strains has been measured between 11
and 16% in studies of soccer, Australian
rules football, and cricket (92). This can
result in an average of 6 players per squad
suffering a hamstring injury (defined as
“preventing player participation in
a match”) each season in professional
soccer and Australian rules football
Impact of the Nordic hamstring and hip extension exercises on hamstring archi...Fernando Farias
The architectural and morphological adaptations of the hamstrings in response to training
33 with different exercises have not been explored. PURPOSE: To evaluate changes in biceps
34 femoris long head (BFLH) fascicle length and hamstring muscle size following 10-weeks of
35 Nordic hamstring exercise (NHE) or hip extension (HE) training. METHODS: Thirty
36 recreationally active male athletes (age, 22.0 ± 3.6 years, height, 180.4 ± 7 cm, weight, 80.8 ±
37 11.1 kg) were allocated to one of three groups: 1) HE training (n=10), NHE training (n=10),
38 or no training (CON) (n=10). BFLH fascicle length was assessed before, during (Week 5) and
39 after the intervention with 2D-ultrasound. Hamstring muscle size was determined before and
40 after training via magnetic resonance imaging.
Eccentric training using external loads greater than the
relative concentric training intensity is a potent stimulus for
enhancements in muscle mechanical function, and MTU
morphological and architectural adaptations. The inclusion
of eccentric loads above maximal concentric strength is
therefore an avenue to induce novel training stimuli and
effect change in key determinants, and functional metrics,
of strength, power and speed performance. Strength
improvements are largely mode-specific and arise from a
combination of neural, morphological and architectural
adaptations [8]. Increased agonist volitional drive is posited
as the primary contributing factor to the marked increases
in eccentric strength observed following training [54].
Eccentric training improves concentric muscle power and
SSC performance to a greater extent than concentric or
traditional modalities
High chronic training loads and exposure to bouts of maximal velocity running...Fernando Farias
The ability to produce high speeds is considered an important
quality for performance, with athletes shown to achieve 85–94% of
maximal velocity during team sport match-play.3 Well-developed
high-speed running ability and maximal velocity are required of
players during competition in order to beat opposition players
to possession and gain an advantage in attacking and defensive
situations.
Acute cardiopulmonary and metabolic responses to high intensity interval trai...Fernando Farias
Results from the present study quantify the effects of altering either the intensity of the
work or the recovery interval when performing interval sessions consisting of 60s of work and
60s of recovery for multiple repetitions. The information provided may aid those interested in
designing interval training sessions by providing ranges of values that could be expected for
individuals who possess moderate levels of cardiopulmonary fitness. Using a work intensity of
80% or 100% VGO2peak and a recovery intensity of 0% or 50% VGO2peak, subjects were able to
exercise within the ACSM recommended range for exercise intensity. Based upon the data it
would appear that a protocol such as the 80/0 may be appropriate for those individuals who
are just beginning a program or have little experience with interval-type activity. By contrast, a
100/50 protocol could not be completed by all of the subjects and therefore may be too intense
for some individuals.
The hamstring muscle group is the most frequently injured, representing
approximately 12 to 24% of all athletic injuries.1,2 These injuries may be due to
disproportionate training performed for the quadriceps,3 with hamstring strains
occurring more frequently in those who demonstrated hamstring weakness, and
lower hamstring-to-quadriceps strength ratios.2 Thus, hamstring strength is impor-
tant for athletic performance and injury prevention in a variety of sports.
Postexercise Cold Water Immersion Benefits Are Not Greater than the Placebo E...Fernando Farias
A CWI placebo is also as effective as
CWI itself in the recovery of muscle strength over 48 h.
This can likely be attributed to improved subjective ratings
of pain and readiness for exercise, suggesting that the hy-
pothesized physiological benefits surrounding CWI may
be at least partly placebo related.
Effects of seated and standing cold water immersion on recovery from repeated...Fernando Farias
There were
no significant group differences between control and either of the cold water immersion interventions. Seated cold water
immersion was associated with lower DOMS than standing cold water immersion (effect size = 1.86; P = 0.001). These
data suggest that increasing hydrostatic pressure by standing in cold water does not provide an additional recovery benefit
over seated cold water immersion, and that both seated and standing immersions have no benefit in promoting recovery
Cold water immersion versus whole body cryotherapyFernando Farias
Cold-water immersion was more effective in
accelerating recovery kinetics than whole-body cryotherapy for countermovement jump
performance at 72h post-exercise. Cold-water immersion also demonstrated lower soreness
and higher perceived recovery levels across 24-48h post-exercise.
The effectiveness of exercise interventions to prevent sports injuriesFernando Farias
Strength training reduced sports injuries to less
than one-third. We advocate that multiple exposure interven-
tions should be constructed on the basis of well-proven single
exposures and that further research into single exposures, par-
ticularly strength training, remains crucial. Both acute and
overuse injuries could be significantly reduced, overuse injuries
by almost a half.
Training the vertical jump to head the ball in soccer Fernando Farias
IN MODERN SOCCER, HEADING
THE BALL IS BOTH AN OFFENSIVE
TOOL USED TO SCORE GOALS
AND A DEFENSIVE MEASURE
AGAINST OPPOSING TEAMS. PRO-
FICIENCY IN HEADING THE BALL
REQUIRES PROPER TECHNIQUE IN
CONJUNCTION WITH AN EFFEC-
TIVE VERTICAL JUMP. THE AIM OF
THIS ARTICLE IS TO ADDRESS THE
FACTORS INVOLVED IN VERTICAL
JUMP PERFORMANCE AND HOW
THEY RELATE SPECIFICALLY TO
HEADING THE BALL
EFFECTS OF STRENGTH TRAINING ON SQUAT AND SPRINT PERFORMANCE IN SOCCER PLAYERSFernando Farias
We have demonstrated that a simple in-season strength training program resulted in an improvement in maximal back squat performance, which was reflected in improve- ments in short sprint performance, as identified by a decrease in sprint time over 5, 10, and 20 m, in professional soccer players, in line with the hypotheses. Furthermore, the changes in relative 1RM squat strength demonstrate strong associations with the changes in 5 (r = 0.62), 10 (r = 0.78), and 20-m (r = 0.60) sprint performances.
Methods of developing power to improve acceleration for the non track athleteFernando Farias
IN MOST TEAM-BASED SPORTS
ATHLETES MUST BE ABLE TO
GENERATE EXPLOSIVE MUSCULAR
FORCES TO ACCELERATE,
CHANGE DIRECTIONS, AND THEN
RE-ACCELERATE OVER RELA-
TIVELY SHORT DISTANCES.
THEREFORE, TO BE SUCCESSFUL,
ACCELERATION RATHER THAN
MAXIMAL VELOCITY IS LIKELY A
GREATER PREDICTOR OF SUC-
CESS IN THESE SPORTS. THIS
ARTICLE WILL EXPLORE SOME OF
THE TECHNIQUES COMMONLY
USED TO IMPROVE AN ATHLETE’S
ABILITY TO ACCELERATE BY
IMPROVING FORCE, VELOCITY,
AND THE COMBINATION OF THESE
2 ELEMENTS.
Soccer, which has a large number of participants, has a high injury incidence that causes
both financial and time burdens. Therefore, knowledge about the epidemiology of soccer injuries
could allow sports-medicine professionals, such as physicians and physiotherapists, to direct their
work in specific preventive programs. Thus, our aim was to conduct an epidemiological survey of
injuries sustained by professional soccer players from the same team who participated in the Brazilian
championship premier league in 2009.
Post exercise cold water immersion attenuates acute anabolic signallingFernando Farias
these two studies offer new and
important insights into how cold water immersion during
recovery from strength exercise affects chronic training
adaptations and some of the molecular mechanisms that
underpin such adaptations. Cold water immersion delayed
or inhibited satellite cell activity and suppressed the
activation of p70S6K after acute strength exercise. These
effects may have been compounded over time to diminish
the expected increases in muscle mass and strength as a
result of training. The results of these studies challenge the
notion that cold water immersion improves recovery after
exercise. Individuals who use strength training to improve
athletic performance, recover from injury or maintain
their health should therefore reconsider whether to use
cold water immersion as an adjuvant to their training.
Maximal sprinting speed of elite soccer playersFernando Farias
Current findings might help individuals involved within the physical preparation of players (e.g. technical coaches, fitness coaches, and sport science staff) when developing training programs and training sessions in line with the playing positions, and with the levels of high speed running targeted to reach during specific training drills like sided-games.
Indeed, the closer to match-play situations regarding the rules with goals, goalkeepers, the larger pitch sizes and greater number of players involved, the higher sprinting speed running players would reach during sided-games. However, coaches are advised to add specific speed drills to sided-games in order to elicit a stimulus of high-speed running high enough to prepare players for competition.
To examine the acute effects of generic (Running Drills, RD) and specific (Small-
Sided Games, SSG) Long Sprint Ability (LSA) drills on internal and external load of male
soccer-players. Methods: Fourteen academy-level soccer-players (mean±SD; age 17.6±0.61
years, height 1.81±0.63 m, body-mass 69.53±4.65 kg) performed four 30s LSA bouts for
maintenance (work:rest, 1:2) and production (1:5) with RD and SSG drills. Players’ external-
load was tracked with GPS technology (20Hz) and heart-rate (HR), blood-lactate
concentrations (BLc) and rate of perceived exertion (RPE) were used to characterize players’
internal-load. Individual peak BLc was assessed with a 30s all-out test on a non-motorized
treadmill (NMT). Results: Compared to SSGs the RDs had a greater effect on external-load
and BLc (large and small, respectively). During SSGs players covered more distance with
high-intensity decelerations (moderate-to-small). Muscular-RPE was higher (small-to-large)
in RD than in SSG. The production mode exerted a moderate effect on BLc while the
maintenance condition elicited higher cardiovascular effects (small-to-large). Conclusion:
The results of this study showed the superiority of generic over specific drills in inducing
LSA related physiological responses. In this regard production RD showed the higher post-
exercise BLc. Interestingly, individual peak blood-lactate responses were found after the
NMT 30s all-out test, suggesting this drill as a valid option to RD bouts. The practical
physiological diversity among the generic and specific LSA drills here considered, enable
fitness trainers to modulate prescription of RD and SSG drills for LSA according to training
schedule.
Short inter-set rest blunts resistance exercise-inducedFernando Farias
Manipulating the rest-recovery interval between sets of resistance exercise may influence
training-induced muscle remodelling. The aim of this study was to determine the acute muscle
anabolic response to resistance exercise performed with short or long inter-set rest intervals.
In a study with a parallel-group design, 16 males completed four sets of bilateral leg-press and
knee-extension exercise at 75% of one-repetition maximum to momentary muscular failure,
followed by ingestion of 25 g of whey protein. Resistance exercise sets were interspersed by
1 min (n = 8) or 5 min of passive rest (n = 8). Muscle biopsies were obtained at rest, 0, 4, 24
and 28 h postexercise during a primed continuous infusion of l-[ring-13C6]phenylalanine to
determine myofibrillar protein synthesis and intracellular signalling.
The effects of self-myofascial release using a foam roll or roller massager on joint range of motion, muscle recovery, and performance: a systematic review
Melhorar ou até mesmo manter o desempenho atlético em jogadores de esportes de equipe competitivos durante o longo período da temporada é um dos maiores desafios para qualquer treinador comprometido. Tempo muito limitado está disponível entre as partidas semanais para introduzir sessões intensivas de treinamento de força e poder, com uma freqüência normal de 1-2 unidades por semana. Este fato estimula a busca de métodos de treinamento mais eficientes capazes de melhorar uma ampla variedade de habilidades funcionais, evitando ao mesmo tempo os efeitos de fadiga.
Os resultados atuais indicaram que a ocorrência de lesões de isquiotibiais podem estar associadas a uma mudança hierárquica na distribuição da atividade metabólica dentro do complexo muscular do isquiotibial após o trabalho excêntrico em que o Semitendinoso provavelmente deveria tomar a parte principal, seguido pelo BÍceps Femural e Semimembranoso. Quando o BF aumenta sua contribuição e é ativado em uma extensão proporcionalmente maior, o risco de sofrer uma lesão do isquiotibial pode aumentar substancialmente.
Hamstring strain prevention in elite soccer playersFernando Farias
Hamstring strains are among the most
common injury in sport and are most
often observed in sports that involve
sprinting, turning, and jumping
(8,38,63). The prevalence of hamstring
strains has been measured between 11
and 16% in studies of soccer, Australian
rules football, and cricket (92). This can
result in an average of 6 players per squad
suffering a hamstring injury (defined as
“preventing player participation in
a match”) each season in professional
soccer and Australian rules football
Impact of the Nordic hamstring and hip extension exercises on hamstring archi...Fernando Farias
The architectural and morphological adaptations of the hamstrings in response to training
33 with different exercises have not been explored. PURPOSE: To evaluate changes in biceps
34 femoris long head (BFLH) fascicle length and hamstring muscle size following 10-weeks of
35 Nordic hamstring exercise (NHE) or hip extension (HE) training. METHODS: Thirty
36 recreationally active male athletes (age, 22.0 ± 3.6 years, height, 180.4 ± 7 cm, weight, 80.8 ±
37 11.1 kg) were allocated to one of three groups: 1) HE training (n=10), NHE training (n=10),
38 or no training (CON) (n=10). BFLH fascicle length was assessed before, during (Week 5) and
39 after the intervention with 2D-ultrasound. Hamstring muscle size was determined before and
40 after training via magnetic resonance imaging.
Eccentric training using external loads greater than the
relative concentric training intensity is a potent stimulus for
enhancements in muscle mechanical function, and MTU
morphological and architectural adaptations. The inclusion
of eccentric loads above maximal concentric strength is
therefore an avenue to induce novel training stimuli and
effect change in key determinants, and functional metrics,
of strength, power and speed performance. Strength
improvements are largely mode-specific and arise from a
combination of neural, morphological and architectural
adaptations [8]. Increased agonist volitional drive is posited
as the primary contributing factor to the marked increases
in eccentric strength observed following training [54].
Eccentric training improves concentric muscle power and
SSC performance to a greater extent than concentric or
traditional modalities
High chronic training loads and exposure to bouts of maximal velocity running...Fernando Farias
The ability to produce high speeds is considered an important
quality for performance, with athletes shown to achieve 85–94% of
maximal velocity during team sport match-play.3 Well-developed
high-speed running ability and maximal velocity are required of
players during competition in order to beat opposition players
to possession and gain an advantage in attacking and defensive
situations.
Acute cardiopulmonary and metabolic responses to high intensity interval trai...Fernando Farias
Results from the present study quantify the effects of altering either the intensity of the
work or the recovery interval when performing interval sessions consisting of 60s of work and
60s of recovery for multiple repetitions. The information provided may aid those interested in
designing interval training sessions by providing ranges of values that could be expected for
individuals who possess moderate levels of cardiopulmonary fitness. Using a work intensity of
80% or 100% VGO2peak and a recovery intensity of 0% or 50% VGO2peak, subjects were able to
exercise within the ACSM recommended range for exercise intensity. Based upon the data it
would appear that a protocol such as the 80/0 may be appropriate for those individuals who
are just beginning a program or have little experience with interval-type activity. By contrast, a
100/50 protocol could not be completed by all of the subjects and therefore may be too intense
for some individuals.
The hamstring muscle group is the most frequently injured, representing
approximately 12 to 24% of all athletic injuries.1,2 These injuries may be due to
disproportionate training performed for the quadriceps,3 with hamstring strains
occurring more frequently in those who demonstrated hamstring weakness, and
lower hamstring-to-quadriceps strength ratios.2 Thus, hamstring strength is impor-
tant for athletic performance and injury prevention in a variety of sports.
Postexercise Cold Water Immersion Benefits Are Not Greater than the Placebo E...Fernando Farias
A CWI placebo is also as effective as
CWI itself in the recovery of muscle strength over 48 h.
This can likely be attributed to improved subjective ratings
of pain and readiness for exercise, suggesting that the hy-
pothesized physiological benefits surrounding CWI may
be at least partly placebo related.
Effects of seated and standing cold water immersion on recovery from repeated...Fernando Farias
There were
no significant group differences between control and either of the cold water immersion interventions. Seated cold water
immersion was associated with lower DOMS than standing cold water immersion (effect size = 1.86; P = 0.001). These
data suggest that increasing hydrostatic pressure by standing in cold water does not provide an additional recovery benefit
over seated cold water immersion, and that both seated and standing immersions have no benefit in promoting recovery
Cold water immersion versus whole body cryotherapyFernando Farias
Cold-water immersion was more effective in
accelerating recovery kinetics than whole-body cryotherapy for countermovement jump
performance at 72h post-exercise. Cold-water immersion also demonstrated lower soreness
and higher perceived recovery levels across 24-48h post-exercise.
The effectiveness of exercise interventions to prevent sports injuriesFernando Farias
Strength training reduced sports injuries to less
than one-third. We advocate that multiple exposure interven-
tions should be constructed on the basis of well-proven single
exposures and that further research into single exposures, par-
ticularly strength training, remains crucial. Both acute and
overuse injuries could be significantly reduced, overuse injuries
by almost a half.
Training the vertical jump to head the ball in soccer Fernando Farias
IN MODERN SOCCER, HEADING
THE BALL IS BOTH AN OFFENSIVE
TOOL USED TO SCORE GOALS
AND A DEFENSIVE MEASURE
AGAINST OPPOSING TEAMS. PRO-
FICIENCY IN HEADING THE BALL
REQUIRES PROPER TECHNIQUE IN
CONJUNCTION WITH AN EFFEC-
TIVE VERTICAL JUMP. THE AIM OF
THIS ARTICLE IS TO ADDRESS THE
FACTORS INVOLVED IN VERTICAL
JUMP PERFORMANCE AND HOW
THEY RELATE SPECIFICALLY TO
HEADING THE BALL
EFFECTS OF STRENGTH TRAINING ON SQUAT AND SPRINT PERFORMANCE IN SOCCER PLAYERSFernando Farias
We have demonstrated that a simple in-season strength training program resulted in an improvement in maximal back squat performance, which was reflected in improve- ments in short sprint performance, as identified by a decrease in sprint time over 5, 10, and 20 m, in professional soccer players, in line with the hypotheses. Furthermore, the changes in relative 1RM squat strength demonstrate strong associations with the changes in 5 (r = 0.62), 10 (r = 0.78), and 20-m (r = 0.60) sprint performances.
Methods of developing power to improve acceleration for the non track athleteFernando Farias
IN MOST TEAM-BASED SPORTS
ATHLETES MUST BE ABLE TO
GENERATE EXPLOSIVE MUSCULAR
FORCES TO ACCELERATE,
CHANGE DIRECTIONS, AND THEN
RE-ACCELERATE OVER RELA-
TIVELY SHORT DISTANCES.
THEREFORE, TO BE SUCCESSFUL,
ACCELERATION RATHER THAN
MAXIMAL VELOCITY IS LIKELY A
GREATER PREDICTOR OF SUC-
CESS IN THESE SPORTS. THIS
ARTICLE WILL EXPLORE SOME OF
THE TECHNIQUES COMMONLY
USED TO IMPROVE AN ATHLETE’S
ABILITY TO ACCELERATE BY
IMPROVING FORCE, VELOCITY,
AND THE COMBINATION OF THESE
2 ELEMENTS.
Soccer, which has a large number of participants, has a high injury incidence that causes
both financial and time burdens. Therefore, knowledge about the epidemiology of soccer injuries
could allow sports-medicine professionals, such as physicians and physiotherapists, to direct their
work in specific preventive programs. Thus, our aim was to conduct an epidemiological survey of
injuries sustained by professional soccer players from the same team who participated in the Brazilian
championship premier league in 2009.
Post exercise cold water immersion attenuates acute anabolic signallingFernando Farias
these two studies offer new and
important insights into how cold water immersion during
recovery from strength exercise affects chronic training
adaptations and some of the molecular mechanisms that
underpin such adaptations. Cold water immersion delayed
or inhibited satellite cell activity and suppressed the
activation of p70S6K after acute strength exercise. These
effects may have been compounded over time to diminish
the expected increases in muscle mass and strength as a
result of training. The results of these studies challenge the
notion that cold water immersion improves recovery after
exercise. Individuals who use strength training to improve
athletic performance, recover from injury or maintain
their health should therefore reconsider whether to use
cold water immersion as an adjuvant to their training.
Evaluation of the match external load in soccerFernando Farias
In modern soccer training control and regulation is regarded as a relevant
methodological procedure to optimize training adaptations to maximize match performance 1-
3
. Training progress is the result of the interplay of external and internal loads imposed on
players during training sessions 2
. Although physiological adaptations are mediated by
internal load functional variation the doses necessary for obtaining them are practically seized
monitoring training external load 4
. The recent exponential advancement of match analysis
systems such as multi-camera and Global Position System Technology has enabled the
evaluation of player’s external load during specific training in elite and sub-elite competitive
and recreational soccer
Hamstring injuries have increased by 4% annuallyFernando Farias
Muscle injuries are a substantial problem for pro-
fessional football players. They constitute more
than one-third of all time-loss injuries and cause
more than a quarter of the total injury absence in
high-level European professional football clubs.1
Hamstring injury is the most common injury
subtype, representing 12% of all injuries, and a
team with a 25 player-squad typically suffers about
5–6 hamstring injuries each season, equivalent to
more than 80 days involving football activities
(training or matches) lost due to injury.
a literatura apresenta dados sugerindo
que o alongamento estático, realizado como componente do
aquecimento, pode diminuir o desempenho subsequente
para movimentos que exigem força máxima e potência
muscular, como em “sprints” simples, ou diminuindo
a capacidade de sua execução múltipla, em inglês
conhecida como “Repeated Sprint Ability” (RSA)
Effect of cold water immersion on skeletal muscle contractile properties in s...Fernando Farias
This study shows that repeated cold-water immersions (4
4 mins at 4-C) cause considerable alterations to muscle behavior. These alter-
ations signififiantly affect the state of muscles and their response capacity, partic-
ularly in relation to muscle stiffness and muscle contraction velocity.
SPRINT SPEED IS RELATED TO
THE ABILITY TO DEPLETE LARGE
AMOUNTS OF HIGH-ENERGY
PHOSPHATES AT A FAST RATE.
TO SPRINT REPEATEDLY,
THE AEROBIC SYSTEM MUST
RESYNTHESIZE POLYMERASE
CHAIN REACTION, REMOVE
ACCUMULATED INTRACELLULAR
INORGANIC PHOSPHATE, AND
OXIDIZE LACTATE DURING REST
PERIODS. WHETHER THIS CAN
BE APPRECIABLY IMPROVED
VIA A HIGH V̇
O2MAX REMAINS
CONTROVERSIAL. HOWEVER, IT IS
LIKELY IMPROVED VIA ANAEROBIC
QUALITIES SUCH AS STRENGTH,
POWER, AND SPEED, ALONG
WITH THE ATHLETE’S VELOCITY
AT ONSET OF BLOOD LACTATE
ACCUMULATION. WHEN
REPORTING REPEAT SPRINT
ABILITY TEST RESULTS, TOTAL
OR MEAN TIME SHOULD BE USED.
Consideraciones sobre la manifestación y el desarrollo de la fuerza y la pot...Fernando Farias
La mejora de la fuerza muscular se ha atribuido tanto al aumento de la sección
transversal del músculo como a la coordinación neuromuscular. Típicamente,
para el aumento de la masa muscular se utilizan cargas medias (70-80% de
1RM), con las que se realiza el máximo o casi máximo número de repeticiones
por serie posible, mientras que la mejora de los factores neuromusculares se
asocia con la aplicación de cargas altas, iguales o superiores al 85% de 1RM. No
obstante, tanto los cambios estructurales como la activación y mejora de la
función neuromuscular parece que dependen también en gran medida de la
intención del sujeto en alcanzar la máxima producción de fuerza en la unidad de
tiempo en cada acción muscular, cualquiera que sea la carga que se utilice.
(González-Badillo y Serna, 2002, Behm y Sale, 1993). Por tanto, factores de tipo
dinámico y cinemático, como la fuerza y la velocidad relativas alcanzadas al
desplazar una carga, constituyen una parte importante del desarrollo y la
manifestación de la fuerza.
Periodização “Convencional” Transporta a noção de que não é possível manter a "forma" durante toda a época competitiva. Originando a procura de "picos de forma", com base nos efeitos retardados das cargas.
Con excepción del fútbol de alto nivel, en el que el refuerzo
de los equipos técnicos permite al entrenador contar con
el apoyo de un gran número de asistentes, expertos y
especialistas en sus respectivos campos, la mayoría de los
entrenadores y sus asistentes se enfrentan con frecuencia a
los mismos problemas:
– Cómo mantener o desarrollar las cualidades físicas de los
jugadores: cualidades fundamentales del rendimiento.
– Cómo reforzar el nivel técnico-táctico de su equipo:
cualidad esencial para apoyar eficazmente un proyecto
de juego y para asegurar un equilibrio permanente del
sistema de juego mediante la recuperación colectiva del
balón y su conservación y circulación eficaz, para optimizar
la definición.
O programa de estabilização central é indicado para várias lesões, dentre as quais podemos citar as lombalgias crônicas, as discopatias, as artroses, as alterações posturais importantes; preparação de atletas de alto nível; síndrome cruzada; processo traumático; e situação que levam desequilíbrio biomecânico da coluna lombar. Um atraso na resposta dos músculos do tronco para perturbação tem um grande potencial para provocar uma instabilidade central, com isso há um grande risco para lombalgia crônica, pois uma das causas de lombalgia é a instabilidade da coluna lombar (O’SULLIVAN, 2000).
Analysis of Lower Limb Bilateral Force Asymmetries by Different Vertical Jump...IJRTEMJOURNAL
This study has compared the diagnostic information of lower limb bilateral force asymmetry by
the impulse variable at different vertical jumps techniques. Twenty-nine soccer players carried out six attempts
at each of the vertical jumps, countermovement jump and squat jump, on two synchronized force platforms.
After the calculation of the symmetry index, the athletes were classified as symmetric and asymmetric respecting
a cut-off value of 15%, McNamara’s test compared the diagnostic information among the techniques.
Significant differences were found among the diagnostic information of the different techniques (p<0.05). It is
thus concluded that different vertical jump techniques provide different information in regard to the level of
bilateral force asymmetry in soccer players.
Analysis of Lower Limb Bilateral Force Asymmetries by Different Vertical Jump...IJRTEMJOURNAL
This study has compared the diagnostic information of lower limb bilateral force asymmetry by
the impulse variable at different vertical jumps techniques. Twenty-nine soccer players carried out six attempts
at each of the vertical jumps, countermovement jump and squat jump, on two synchronized force platforms.
After the calculation of the symmetry index, the athletes were classified as symmetric and asymmetric respecting
a cut-off value of 15%, McNamara’s test compared the diagnostic information among the techniques.
Significant differences were found among the diagnostic information of the different techniques (p<0.05). It is
thus concluded that different vertical jump techniques provide different information in regard to the level of
bilateral force asymmetry in soccer players
Effect of shoes containing nanosilica particles on knee valgus in active fema...Nanomedicine Journal (NMJ)
Abstract
Objective(s):
The effect of silica nanoparticles (SNPs) in sport shoes outsoles on the parameters related to anterior cruciate ligament (ACL) Injury has not been investigated. The aim of this study was to investigate the effect of shoes outsole containing a composite of thermoplastic elastomer based on styrene-butadiene and silica nanoparticles (TPEN shoe) on Knee Valgus Angle (KVA) as a risk factor of ACL injuries during landing.
Materials and Methods:
Fourteen active healthy women without knee injuries and disorders performed bilateral drop jump (DJ) and single leg drop landing (SLL) tasks in barefoot, wearing shoes fabricated with polyvinyl chloride outsole (PVC shoe) and TPEN shoes conditions , randomly. The knee valgus angle values of right and left legs were calculated in the landing conditions. Two factors repeated measures ANOVA were used to investigate the effect of landing and footwear conditions on KVA of right and left legs.
Results:
For both left and right limbs, the KVA was at maximum and minimum values during landing with barefoot and TPEN shoes, respectively. PVC shoe significantly reduced the knee valgus by 3.84% in left and 4.18% in right knee (P<0.05)><0.05).
Conclusion:
Shod landing and specially TPEN shoe decreases KVA compared to barefoot. Our results suggested that using SNPs could produce some viscoelasticity property and a better joint movement control in shoe outsoles which can reduce KVA and consequent reduction of ACL Injury.
Differences in landing and balance deficits at the ankle joint on stable and ...AJHSSR Journal
ABSTRACT: A flexible ankle joint is suggested to be a contributing factor for sport performance, body
control. The purpose of the present study was to investigate the differences in proprioception in static and
dynamic movements between subjects with good ankle joint mobility (FL) and poor ankle joint mobility (IN) in
male adolescent handball players. The dorsiflexion and plantarflexion of the ankle ROM was measured, at knee
extension angle of 120°, with a goniometer. 26 male handball players participated (21.1 ± 4 yrs, 80.8 ± 10 kg,
182 ± 7.38 cm). Furthermore, the players fulfilling previously recommended criteria were assigned to the
flexible (n = 6) and inflexible (n = 6) groups and executed two test of static and dynamic movement (BESS Test
and Star Excursion Balance Test). Results of the T TEST on IMB SPSS 26 revealed a significant (p < 0.05)
group effect as (FL) group had less errors than (IN) group on BESS test. In addition, the results of the total sum
on stable and unstable surface in star excursion test showed significant differences in the directions:
anterolateral (7.4), posterolateral (8.6), posteromedial (7.9), medial (10.8) and anterior medial (8.1). In
conclusion, there is a correlation between poor ankle joint mobility and poor proprioception, balance control and
athletic movements.
KEYWORDS: ankle stability, ankle joint mobility, BESS test, handball athletes, injury risk, star excursion
balance test
Discus throwing performances and medical classification of wheelchair athlete...Ciro Winckler
CHOW, J. W.; MINDOCK, L. A. Discus throwing performances and medical classification of wheelchair athletes. Medicine and Science in Sports and Exercise, v. 31, n. 9, p. 1272-1279, 1999.
Changes in Body Position during a 2-Minute Push-Up Test by Jennifer K Hewit*, Daniel A Jaffe and Alex J Bedard
In Research & Investigations in Sports Medicine: Crimson Publishers_ Journal of Sports Medicine
Push-ups are a common exercise for individuals of all ages and abilities. Ensuring that the body maintains optimal positioning is crucial throughout any activity. This brief study investigates the changes in hand height and torso angle throughout a 2-minute push-up test. A total of 26 males (23.3±6.9 years old) participated in this study. Video was collected of the entire 2-minute push-up bout. Of interest to the researchers was the distance the hand was in relation to the shoulder and the angle of the torso to the horizontal (both measure from participants' sagittal view). Three consecutive repetitions at the start and end of the bout were used for comparative analysis. Both hand placement in relation to the shoulder and torso angle decreased significantly (p=0.00) from the start of the bout to the end. These results indicate that as participants became tired, they assumed a body position that likely allowed for a greater portion of their body weight to be supported by their lower body. While this adjustment allowed them to continue the exercise, compensational patterns like this should be identified and addressed in training in order to strengthen the primary muscles targeted by the exercise.
Muscular strength, functional performances and injury risk in professional an...Fernando Farias
Muscle strength and anaerobic power of the lower extre-
mities are neuromuscular variables that influence perfor-
mance in many sports activities, including soccer. Despite
frequent contradictions in the literature, it may be assumed
that muscle strength and balance play a key role in targeted
acute muscle injuries. The purpose of the present study was
to provide and compare pre-season muscular strength and
power profiles in professional and junior elite soccer players
throughout the developmental years of 15–21.
A study of selected biomechanical variables as a factor of hitting performanc...IOSR Journals
Abstract: The modern age of sports is the excellence, so in every sports perfection and purification of skill has
got its immense importance. Biomechanics is an applied form of mechanics and consequently the method used
to investigate it must be derived from those of mechanics. Biomechanics aim to explain the mechanics of life.
Sports biomechanics have also generated other efforts at improving athletic performance in different games and
sports; it is helpful to minimize sports injuries through both identifying dangerous practice and designing safer
equipment and apparel. The purpose of this study was to investigate the relationship of selected biomechanical
variables with the hitting performance in softball.
Keywords: Biomechanical Variable, Centre of gravity, Evaluation of technique, Performance, Softball Hitting
Similar to Bilateral and unilateral vertical ground reaction forces (20)
A universalidade das Regras do Jogo significa que o jogo é essencialmente o
mesmo em todas as partes do mundo e em todos os níveis. Bem como promover um
ambiente justo e seguro para a sua prática, as Regras também devem promover a
participação e a diversão.
O jogo deve ser jogado e arbitrado da mesma maneira em todos os campos de
futebol pelo mundo, desde a final da Copa do Mundo FIFA™ até um jogo em um
vilarejo remoto. No entanto, as características locais de cada país devem determinar
a duração da partida, quantas pessoas podem participar e como algumas atitudes
inapropriadas devem ser punidas.
A evidência apresentada sugere que a variação é um componente necessário do planejamento efetivo do treinamento. Apoiando essa perspectiva, outras pesquisas sugerem que a monotonia de treinamento elevado - que pode ser amplamente percebida como uma falta de variação20 - leva a uma maior incidência de síndromes de overtraining21, um mau desempenho e freqüência de infecções banais.22 Inversamente, as reduções na monotonia têm Tem sido associada a uma maior incidência de melhor desempenho pessoal 22, e os índices de monotonia têm sido defendidos como ferramentas benéficas de treinamento-regulação na elite rowing23 e no sprint24.
Capacidade manter as ações de jogo em alto
padrão de execução durante 90 minutos. É
muito importante no segundo tempo que é
onde ocorre o maior número de gols e
normalmente se decidem as partidas.
A literatura atual que mede os efeitos de SMR ainda está emergindo. Os resultados desta análise sugerem que o rolamento de espuma e a massagem com rolo podem ser intervenções eficazes para melhorar a ROM conjunta e o desempenho muscular pré e pós-exercício. No entanto, devido à heterogeneidade dos métodos entre os estudos, atualmente não há consenso sobre o ótimo programa SMR.
Actualmente la capacidad de repetir sprints es considerada fundamental en el rendimiento del fútbol por
parecerse al patrón de movimiento que se da en el mismo. De esta manera su entrenamiento resulta fundamental
en cualquier planificación. Así, se deben trabajar aquellos aspectos que la limitan para poder acceder a un mayor
rendimiento. Una vez conocido esto se debería elegir la forma en la que se quiere entrenar, teniendo para ello
métodos analíticos (interválico, intermitente) y contextualizados (espacios reducidos). Por último, se proponen
una series de variables de entrenamiento para el trabajo de repetir sprints, orientándolo no solo al aspecto físico,
sino también al técnico, táctico y psicológico, conformando, por tanto, un entrenamiento integrado en el fútbol.
Recovery in Soccer Part I – Post-Match Fatigue and Time Course of RecoveryFernando Farias
In elite soccer, players are frequently required to play consecutive matches
interspersed by 3 days and complete physical performance recovery may not
be achieved. Incomplete recovery might result in underperformance and in-
jury. During congested schedules, recovery strategies are therefore required
to alleviate post-match fatigue, regain performance faster and reduce the risk
of injury. This article is Part I of a subsequent companion review and deals
with post-match fatigue mechanisms and recovery kinetics of physical per-
formance (sprints, jumps, maximal strength and technical skills), cognitive,
subjective and biochemical markers.
Hip extension and Nordic hamstring exercise training both promote the elongation of
biceps femoris long head fascicles, and stimulate improvements in eccentric knee
flexor strength.
Hip extension training promotes more hypertrophy in the biceps femoris long head
and semimembranosus than the Nordic hamstring exercise, which preferentially
develops the semitendinosus and the short head of biceps femoris
No sentido de melhor esclarecer esta forma de operacionalizar o processo
de treino procuramos num primeiro momento sistematizar os aspectos
conceptometodológicos que a definem. Contudo, a “Periodização Táctica”
é uma concepção que se encontra pouco retratada na literatura e por isso,
deparamo-nos com escassas referências bibliográficas levando-nos a
reequacionar o teor deste trabalho. Neste seguimento, decidimos incidir
nos fundamentos conceptometodológicos que a definem, a partir de dados
empíricos do processo de treino-competição do treinador José Guilherme
Oliveira
. A escolha deste treinador deve-se ao facto de ser reconhecido pelo
professor Vítor Frade como um dos treinadores que operacionaliza o processo
de treino tendo em conta as premissas da “Periodização Táctica”.
The quadriceps femoris is traditionally described as a muscle group com-
posed of the rectus femoris and the three vasti. However, clinical experience
and investigations of anatomical specimens are not consistent with the text-
book description. We have found a second tensor-like muscle between the
vastus lateralis (VL) and the vastus intermedius (VI), hereafter named the
tensor VI (TVI). The aim of this study was to clarify whether this intervening
muscle was a variation of the VL or the VI, or a separate head of the exten-
sor apparatus. Twenty-six cadaveric lower limbs were investigated...
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Mats André Zuccarello Aasen, commonly known as Mats Zuccarello, was born on September 1, 1987, in
Oslo, Norway. He grew up in the bustling neighborhood of Løren, where his passion for ice hockey began
at a young age. His mother, Anita Zuccarello, is of Italian descent, and his father, Glenn Aasen, is
Norwegian. This multicultural background played a significant role in shaping his identity and versatility
on and off the ice.
Narrated Business Proposal for the Philadelphia Eaglescamrynascott12
Slide 1:
Welcome, and thank you for joining me today. We will explore a strategic proposal to enhance parking and traffic management at Lincoln Financial Field, aiming to improve the overall fan experience and operational efficiency. This comprehensive plan addresses existing challenges and leverages innovative solutions to create a smoother and more enjoyable experience for our fans.
Slide 2:
Picture this: It’s a crisp fall afternoon, driving towards Lincoln Financial Field. The atmosphere is electric—tailgaters grilling, fans in Eagles jerseys creating a sea of green and white. The air buzzes with camaraderie and anticipation. You park, join the throng, and make your way to your seat. The stadium roars as the Eagles take the field, sending chills down your spine. Each play is a thrilling dance of strategy and skill. This is what being an Eagles fan is all about—the joy, the pride, and the shared experience.
Slide 3:
But now, the day is marred by frustration. The excitement wanes as you struggle to find a parking spot. The congestion is overwhelming, and tempers flare. The delays mean you miss the pre-game excitement, the tailgate camaraderie, and even the opening kick-off. After the game, the joy of victory or the shared solace of defeat is overshadowed by the stress of navigating out of the parking lot. The gridlock, honking horns, and endless waiting drain the energy and joy from what should have been an unforgettable experience.
Our proposal aims to eliminate these frustrations, ensuring that from arrival to departure, your experience is extraordinary. Efficient parking and smooth traffic flow are key to maintaining the high spirits and excitement that make game days special.
Slide 4:
The Philadelphia Eagles are not just a premier NFL team; they are an integral part of the community, hosting games, concerts, and various events at Lincoln Financial Field. Our state-of-the-art stadium is designed to provide a world-class experience for every attendee. Whether it's the thrill of game day, the excitement of a live concert, or the camaraderie of community events, we pride ourselves on delivering a fan-first experience and maintaining operational excellence across all our activities. Our commitment to our fans and community is unwavering, and we continuously strive to enhance every aspect of their experience, ensuring they leave with unforgettable memories.
Slide 5:
Recent trends show an increasing demand for efficient event logistics. Our customer feedback has consistently highlighted frustrations with parking and traffic. Surveys indicate that a significant number of fans are dissatisfied with the current parking situation. Comparisons with other venues like Citizens Bank Park and Wells Fargo Center reveal that we lag in terms of parking efficiency and convenience. These insights underscore the urgent need for innovation to meet and exceed fan expectations.
Slide 6:
As we delve into the intricacies of our operations, one glaring issue emer
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Bilateral and unilateral vertical ground reaction forces
1. Biology of Sport, Vol. 33 No2, 2016 179
Bilateral asymmetries in soccer players
INTRODUCTION
Individual technique, tactics and physical resources, such as the
energy delivery system, are all important when evaluating performance
differences in soccer [1], even though it is difficult to discriminate
between the relative importance of each of these elements [1].
The energy delivery system during a soccer game is characterized by
a high demand of both aerobic and anaerobic metabolism [2]. Fur-
thermore, since during a soccer game the prevalence of sprints, jumps,
tackles and dual plays is very high, the neuromuscular perfor-
mance [3], the anaerobic metabolism, and specifically, the anaerobic
power of the lower extremities, have been pointed out as crucial fac-
tors for the match outcome [4].
Anaerobic power evaluation of the lower extremities in soccer
players has been frequently performed using free weights [5] and
isokinetic dynamometry [6-8]. Although these methods have been
widely used, some authors consider that these tests do not reflect
the functional aspects of physical demands involved in soccer prac-
tice [2]. Nevertheless, since vertical jump (VJ) tests also measure
the anaerobic power of the lower legs and have been previously used
for talent selection in soccer [4], they seem more appropriate tests
for soccer players. Furthermore, counter movement jumps (CMJs)
Bilateral and unilateral vertical ground reaction forces and leg
asymmetries in soccer players
AUTHORS: Yanci J, Camara J
Department of Physical Education and Sport, Faculty of Education and Sport, University of the Basque Country,
UPV/EHU, Vitoria-Gasteiz, Spain
ABSTRACT: The purposes of this study were to assess unilateral and bilateral vertical jump performance
characteristics, and to compare the vertical ground reaction force characteristics of the impulse and landing
phase of a vertical jump between the dominant and non-dominant leg in soccer players. The sample consisted
of 20 male soccer players (22.80 ± 2.71 years, 1.88 ± 0.06 m, 76.47 ± 8.80 kg) who competed in the third
division of the Spanish football league. Vertical jump performance was determined by testing the impulse and
landing phase of a bilateral vertical jump, dominant leg vertical jump and non-dominant leg vertical jump.
Significant differences (p 0.05) between dominant and non-dominant legs were found in counter movement
jump (CMJ) flight time (LA = -2.38%, d = 0.33), CMJ flight height (LA = -4.55%, d = 0.33) and CMJ speed
take-off (LA = -2.91%, d = 0.42). No significant differences were found between the dominant and non-
dominant leg in the F1 and F2 magnitudes during the landing phase, the time from the first contact of the foot
with the ground to the production of F1, the time from the second contact of the foot with the ground to the
production of F2, and the time to stabilization of the landing phase. Although differences were found between
the dominant and non-dominant leg in the impulse phase of the jump, no significant differences were found
between dominant and non-dominant legs in the landing phase of vertical jump variables.
CITATION: Yanci J, Camara J. Bilateral and unilateral vertical ground reaction forces and leg asymmetries in
soccer players. Biol Sport. 2016;33(2):179–183.
Received: 2015-10-28; Reviewed: 2015-11-14; Re-submitted: 2016-01-13; Accepted: 2016-01-19; Published: 2016-04-02.
have been related to competitive success in elite-standard soccer
teams [5, 9].
Bilateral vertical jumps (i.e. using both legs during the push-off
phase) have been widely used in soccer players [9-12]. However,
since many jumps and most propulsive forces are generated in a
unilateral fashion, unilateral jump assessments would appear to
have the advantage of reproducing specific movement patterns [13].
Unilateral jump assessment may therefore be of greater prognostic/
diagnostic value to the strength and conditioning practitioner and
consequently offer better training information [13]. Furthermore,
since some studies suggest that bilateral strength asymmetry can
be a risk factor for musculoskeletal injuries [8, 14], unilateral verti-
cal jump assessment may be useful for identifying athletes at in-
creased risk of incurring lower-leg injuries during training and com-
petition [15]. Despite the importance of unilateral actions in soccer,
there are few studies examining unilateral vertical jump perfor-
mance [13, 16].
Considering the relationship between lower leg impacts, such as
the impacts produced during the landing phase of a jump and over-
use injuries [17, 18], not only the vertical jump capacity should be
Original Paper Biol. Sport 2016;33:179-183DOI: 10.5604/20831862.1198638
Key words:
Football
Strength
Imbalance
Test
Muscle
Power
Corresponding author:
Javier Yanci
Faculty of Education and Sport
University of the Basque Country,
UPV/EHU,
Lasarte 71, 01007,
Vitoria-Gasteiz, Spain
E-mail: javier.yanci@ehu.es
-----
2. 180
Yanci J et al.
assessed, but also the landing phase from vertical jumps. It has also
been observed that soccer players are prone to developing lower leg
injuries [19]. The landing phase is characterized by a vertical ground
reaction force (VGRF) that comprises two peaks corresponding to
forefoot (F1) and rear foot (F2) contact with the ground [20]. High
VGRFs have been identified as the main causes of soccer injury [21,
22], owing to the stress that they place on the musculoskeletal
system [23].
The purposes of this study were to assess unilateral and bilateral
vertical jump performance characteristics, and to compare the verti-
cal ground reaction force characteristics of the impulse and landing
phase of a vertical jump between the dominant and non-dominant
leg in soccer players.
MATERIALS AND METHODS
The sample consisted of 20 male amateur soccer players (22.80 ±
2.71 years, 1.88 ± 0.06 m, 76.47 ± 8.80 kg, 22.58 ± 2.08
kg · m-2
) competing in the third division of the Spanish soccer league.
They had performed physical training (endurance, sprint and spe-
cific soccer skills) during 3-4 days per week, for more than 8 years.
Written informed consent was obtained from each of the participants
after a detailed written and oral explanation of the potential risks and
benefits resulting from their participation. Participants were also
informed that they had the option to voluntarily withdraw from the
study at any time. The study was conducted according to the Dec-
laration of Helsinki and with the consent of the club to which par-
ticipants belonged. The study was approved by the local Ethics
Committee.
Procedures
This study was designed to assess vertical jump performance during
bilateral and unilateral jumps. A cross-sectional design was imple-
mented using male soccer players as participants. Additionally, func-
tional leg asymmetries between dominant and non-dominant legs
during unilateral vertical jumping were assessed. Tests were carried
out in the in-season (May). Participants were required to attend the
exercise testing on two occasions. During the first visit, participants
carried out familiarization tests after signing the informed consent,
and their anthropometric characteristics were recorded. During the
second visit, two days after the first visit, vertical jump tests were
performed after a standardized warm-up consisting of 7 min of self-
paced low-intensity running and two 15 m sprints. Bilateral and
unilateral countermovement jumps were also performed during the
warm-up.
Physical characteristics
Height (m), body mass (kg) and body mass index (kg · m-2
) were
measured in each participant. Height was measured to the nearest
0.001 m using a stadiometer (Holtain Ltd, Crymych, United King-
dom). Body mass was obtained to the nearest 0.1 kg using an
electronic scale (Seca Instruments Ltd, Hamburg, Germany). Body
mass index (BMI) was calculated using body weight and height
(kg · m-2
).
Vertical counter movement jump (CMJ) tests
According to the procedures proposed by Maulder and Cronin [24],
participants performed 9 CMJs: 3 bilateral jumps where both legs
were used during the push-off phase (CMJ), 3 unilateral jumps where
the dominant leg (CMJD) was used during the push-off phase and
3 unilateral jumps where the non-dominant leg was used during the
push-off phase (CMJND). Jumps were interspersed with a 20 s re-
covery time. Both legs were used during the landing phase. A force
platform (Quattro Jump, Kistler, Switzerland), at a sampling fre-
quency of 500 Hz, was used to obtain the vertical ground reaction
force data on the push-off and landing phases. The leg that each
player naturally used for striking the ball was considered as the
dominant leg [25]. During the jumps the hands were placed on the
hips and a minimal flexion of the trunk during take-off was permitted.
Jumps not meeting these requirements were repeated. The obtained
parameters were; i) the maximum speed of the centre of gravity
during the take-off, ii) the maximum height of the centre of gravity
during the flight phase, iii) the flight time, iv) the F1 magnitude,
corresponding to forefoot force peak, v) the time from the first contact
of the foot with the ground until the production of F1, vi) the F2
magnitude, corresponding to rear foot force peak, and vii) the time
from the second contact of the foot with the ground until the produc-
tion of F2, and viii) the time to stabilization (TTS). The time to sta-
bilization was determined during the landing phase beginning with
the first contact of the feet with the ground and ending when the
subjects reached and remained within 5% of their body weight [26].
Statistical analysis
The results are presented as mean ± standard deviation (SD). All
the variables were normal and satisfied the equality of variances
according to the Shapiro-Wilk and Levene tests respectively. The
reliability of the jump assessment procedures was calculated using
the coefficient of variation (CV). The CV was calculated for all test
variables to determine the stability of measurement among trials (CV
= (SD/mean) x 100) [27]. Paired t-tests were used to determine if
any significant differences existed between the dominant and non-
dominant leg jump performance during the impulse and landing
phases. Dominant to non-dominant leg asymmetry (LA) was deter-
mined using the following formula: dominant leg - non-dominant leg/
dominant leg · 100 (as previously reported by Newton et al. [28]).
Only the maximum score of each test was included in the data
analysis [29]. Practical significance was assessed by calculating
effect size [30]. Effect sizes (d) were classified as trivial (d 0.2),
small (0.2 d 0.6), moderate (0.6 d 1.2), large (1.2 d
2.0), very large (2.0 d 4.0), nearly perfect (d 4.0), and
perfect (d = infinite). Statistical significance was set at p 0.05.
Data analysis was performed using the Statistical Package for Social
Sciences (version 20.0 for Windows, SPSS Inc, Chicago, IL, USA).
-----
3. Biology of Sport, Vol. 33 No2, 2016 181
Bilateral asymmetries in soccer players
TABLE 2. Results of the parameters characterizing the impulse and flight phases of the unilateral jumps.
RESULTS
The impulse and landing phase of bilateral CMJ test values of the
soccer players are presented in Table 1. The coefficients of varia-
tion (CV) for tests ranged from 2.91% to 6.73%.
The results of the unilateral CMJs of the impulse and flight phas-
es are presented in Table 2. Significant differences were found between
dominant and non-dominant legs in CMJ flight time (LA = -2.38%,
d = 0.33), CMJ flight height (LA = -4.55%, d = 0.33) and CMJ
speed take-off (LA = -2.91%, d = 0.42) values.
No significant differences (Table 3) between the dominant and
non-dominant leg in any of the variables of the landing phase were
found (F1, F2, T1, T2, TTS).
DISCUSSION
This study assessed CMJ performance and asymmetries between the
dominant and non-dominant leg in amateur soccer players. To our
knowledge no scientific articles have determined the characteristics
of the CMJ parameters and the one leg vertical jump and the bilat-
eral asymmetries in the landing phase in soccer players. The main
novelty of this study is that no significant differences were found in
the VGRF pattern between the dominant and non-dominant legs.
However, the dominant leg showed a shorter flight time than the
non-dominant leg.
Because lower extremity bilateral asymmetries are suspected to
increase the risk of injury, jeopardizing performance [15, 31], it is
considered relevant to ascertain the lower leg bilateral asymmetries
of one of the most repetitive actions in soccer, such as jumping. In
the present study, significant differences between dominant and non-
dominant legs were found in the impulse and flight variables of the
CMJ variables (flight time LA = -2.38%, flight height LA = -4.55%,
speed take-off LA = -2.91%). Similarly, Menzel et al. [32] found
a 6.77% difference between the right and left leg in vertical jump
values in CMJs in Brazilian professional soccer players. However,
these results contrast with those obtained by Impellizzeri et al. [15]
in athletes and Maulder and Cronin [24] in non-athletes, where the
average lower-leg strength asymmetry value was 0.8%, and 1%,
respectively. The absence of lower extremity asymmetry found in
non-soccer players could lead us to think that actions performed in
this sport, the competition and training methods used may be one
of the reasons for these asymmetries. Therefore, it would be interest-
ing to investigate the effects of different types of strength training
programmes on soccer players in order to reduce these asymmetries.
Regarding the bilateral landings, in our results F1 and F2 were
higher (1.59 and 1.75 times, respectively), and the time to the
TABLE 1. Results of the impulse and landing phase of the bilateral
CMJ (n = 20).
TABLE 3. Results of the parameters characterizing the landing phase during the unilateral counter movement jumps.
Min. Max. Mean ± SD CV (%)
CMJ flight time (s) 0.44 0.63 0.56 ± 0.04 3.76
CMJ flight height (m) 0.24 0.49 0.39 ± 0.06 2.91
CMJ speed take-off (m·s-1
) 2.18 3.10 2.74 ± 0.21 4.59
F1 (BW) 0.69 4.38 2.43 ± 1.03 5.03
F2 (BW) 2.69 8.41 5.50 ± 1.78 6.73
T1 (s) 0.02 0.06 0.03 ± 0.01 4.86
T2 (s) 0.03 0.08 0.05 ± 0.01 5.67
TTS (s) 0.01 0.89 0.44 ± 0.17 3.25
Note: SD = standard deviation, CV = coefficient of variation;
CMJ = counter movement jump; F1 = magnitude of the first peak of the
vertical ground reaction force, F2 = magnitude of the second peak of the
vertical ground reaction force; T1 = time from the first contact of the foot
with the ground until the production of the first peak, T2 = time from the
first contact of the foot with the ground until the production of the second
peak; TTS = time to stabilization.
Dominant leg Non dominant leg LA (%) d
CMJ flight time (s) 0.42 ± 0.03 0.43 ± 0.03* -2.38 0.33
CMJ jump height (m) 0.22 ± 0.03 0.23 ± 0.03* -4.55 0.33
CMJ speed off (m·s-1
) 2.06 ± 0.14 2.12 ± 0.14* -2.91 0.42
Dominant leg CV (%) Non dominant leg CV (%) LA (%) d
F1 (BW) 1.29 ± 0.50 4.52 1.23 ± 0.40 5.09 4.71 0.12
F2 (BW) 3.55 ± 7.66 3.46 3.64 ± 0.73 2.87 -2.50 0.11
T1 (s) 0.03 ± 0.01 2.02 0.03 ± 0.01 3.64 0.00 0.00
T2 (s) 0.05 ± 0.02 1.96 0.05 ± 0.02 1.87 0.00 0.00
TTS (s) 0.45 ± 0.41 4.93 0.44 ± 0.26 3.91 2.22 0.02
Note: CMJ = counter movement jump; LA = asymmetry between the dominant and non-dominant leg; d = Hopkins effect size. * Significant differences
(p 0.05) between dominant and non-dominant leg.
Note: SD = standard deviation, CV = coefficient of variation; LA = leg asymmetry; d = Hopkins effect size; F1 = magnitude of the first peak,
F2 = magnitude of the second peak; T1 = time from the first contact of the foot with the ground until the production of the first peak, T2 = time from
the second contact of the foot with the ground until the production of the second peak; TTS = time to stabilization.
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4. 182
Yanci J et al.
production of these peaks (T1 and T2) shorter (3.01 and 7.13 times,
respectively) compared to the magnitudes reported by previous au-
thors in recreational athletes [33]. Nevertheless, when compared to
semi-professional soccer players, even though the magnitude of F2
was smaller (44.55%), the magnitude of F1 was similar (5.81%).
In spite of the fact that high magnitudes of VGRF have been related
to injuries [34], it has been hypothesized that the unilateral develop-
ment of overuse injuries may be due to the bilaterally asymmetrical
function of the lower extremities [35]. Considering on the one hand
that most soccer players are forced to use one particular leg for ball
kicking and cutting skills [36] and on the other, the relationship
between CMJs and competitive success in elite soccer teams [5, 9],
it is important to ascertain whether soccer players show an asym-
metry between the legs during the landing phase of CMJs. Previous
studies have suggested that there are differences in behaviour between
the dominant and non-dominant legs in landings [37], with the non-
dominant leg sustaining a higher VGRF than the dominant leg. Nev-
ertheless, in the present study the magnitude of the forces related
to the production of injuries (F1 and F2) [20] and the time to the
production of these forces (T1 and F2) did not show significant dif-
ferences between the legs. These results coincide with a previous
study [38] where it was shown that during the landing phase of
running the dominant and non-dominant legs did not show significant
differences in the kinetic pattern. Because a similar VGRF pattern
was found in both legs and because previous studies have shown
differences in the kinematic pattern during landings [39], it is hy-
pothesized that the unilateral development of overuse injuries might
be due to a bilaterally asymmetrical kinematic pattern of the lower
extremities.
CONCLUSIONS
The results of this study revealed significant differences between
dominant and non-dominant legs in CMJ flight time, flight height
and speed take-off values. However, these differences were not ob-
served in any of the landing phase variables (F1, F2, T1, T2, TTS).
This aspect may lead us to consider the need to implement specific
strength training programmes in order to reduce asymmetric differ-
ences in the impulse phase.
Acknowledgments
The authors would like to thank the soccer players and coaches for
the opportunity to carry out this investigation.
Conflict of interests: the authors declared no conflict of interests
regarding the publication of this manuscript.
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