This study investigated the preparation phase of the seated double poling cycle in sledge hockey through biomechanical analysis. A solid-static prototype representing an adult male was used with motion capture and force plates to measure kinematics and kinetics. Results showed peak impact forces occurred before 5 milliseconds post contact. Forces were greatest when preparation began slightly below the horizon. Data provides baseline measures to understand preparation phase importance and insights to improve sledge hockey performance and shoulder joint health.
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.
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.
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.
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.
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)
Muscular Adaptations to Depth jump Plyometric Training: Comparison of Sand vs...Fernando Farias
The purpose of this investigation was to compare the effects of sand
and land depth jump plyometric training on muscular performance in
men. Fourteen healthy men were randomly assigned to one of two
training groups: (a) Sand Depth Jump training (SDJ; N = 7) or (b) Land
Depth Jump training (LDJ; N = 7).
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.
John Orchard
Adjunct Associate Professor, Sydney Medical School, University of Sydney.
-
Hamstrings are most susceptible to injury during the late stance phase of sprinting
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.
Muscle activation during various hamstring exercisesFernando Farias
The main findings of this investigation demonstrate that
there are significant differences in activation within muscles
when comparing all exercises. Although one might expect
similar activation for a given muscle for activities of similar
kinematics, such as the prone leg curl and glute-ham raise,
this is not the case with the data herein
Anthony Shield - is nmi a risk factor for hamstring strain injury MuscleTech Network
Anthony Shield
Senior lecturer, School of Exercise and Nutrition Science Institute of Health and Biomedical Innovation Queensland University of Technology, Brisbane, Australia.
-
Is neuromuscular inhibition a risk factor for hamstring strain?
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.
The effect of instability training on knee joint proprioception and core stre...Fernando Farias
A general 10-week IT program utilizing Swiss balls and body mass as a resistance proved effective for improving knee proprioception as well as trunk flexion and extension strength in previously inactive individuals. The present study demonstrates that the use of body weight as a resis- tance under unstable conditions can provide significant improvements in knee proprioception (for as long as 9 months after training) and trunk strength for the untrained population that should contribute to general health and functionality.
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.
A criteria based progression rehabilitation protocol for hamstring strain injuries presented at the Sports Medicine Australia conference 2015 during the Hamstring symposium
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.
Lower limb alignment in young female athletes is associated with knee joint m...peertechzpublication
Background: Increased rotational forces and knee valgus forces puts strain on the anterior cruciate
ligament, frequently ruptured in female athletes. Increased internal hip rotation and increased knee valgus
alignment, possible risk factors for anterior cruciate ligament rupture, are more common in women than
men.
Bryan Heiderscheit
Professor, Department of Orthopedics and Rehabilitation, Department of Biomedical Engineering, Director, UW Runners' Clinic, Director, Badger Athletic Performance Research, Co-director, UW Neuromuscular Biomechanics Lab, University of Wisconsin-Madison, Madison, WI, USA.
-
Hamstrings are most susceptible to injury during the early stance phase of sprinting
(13th October, Barcelona)
6th MuscleTech Network Workshop
Comparison between Hamstring Lengthening Tendon and Hamstring Tendon Transfer...Service_supportAssignment
Cerebral Palsy (CP) is defined as a non-progressive brain lesion and has many disorders that may affect both movement and posture (Bobath 1991). Spastic cerebral palsy influence 70% of child population with CP and happen when white matter tracks damage between the cortex and the spinal cord. Moreover, a main problem for children with spastic CP is their feet and leg muscles, which might shorten or tighten around certain joints (Bjorklund 2006). C
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)
Muscular Adaptations to Depth jump Plyometric Training: Comparison of Sand vs...Fernando Farias
The purpose of this investigation was to compare the effects of sand
and land depth jump plyometric training on muscular performance in
men. Fourteen healthy men were randomly assigned to one of two
training groups: (a) Sand Depth Jump training (SDJ; N = 7) or (b) Land
Depth Jump training (LDJ; N = 7).
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.
John Orchard
Adjunct Associate Professor, Sydney Medical School, University of Sydney.
-
Hamstrings are most susceptible to injury during the late stance phase of sprinting
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.
Muscle activation during various hamstring exercisesFernando Farias
The main findings of this investigation demonstrate that
there are significant differences in activation within muscles
when comparing all exercises. Although one might expect
similar activation for a given muscle for activities of similar
kinematics, such as the prone leg curl and glute-ham raise,
this is not the case with the data herein
Anthony Shield - is nmi a risk factor for hamstring strain injury MuscleTech Network
Anthony Shield
Senior lecturer, School of Exercise and Nutrition Science Institute of Health and Biomedical Innovation Queensland University of Technology, Brisbane, Australia.
-
Is neuromuscular inhibition a risk factor for hamstring strain?
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.
The effect of instability training on knee joint proprioception and core stre...Fernando Farias
A general 10-week IT program utilizing Swiss balls and body mass as a resistance proved effective for improving knee proprioception as well as trunk flexion and extension strength in previously inactive individuals. The present study demonstrates that the use of body weight as a resis- tance under unstable conditions can provide significant improvements in knee proprioception (for as long as 9 months after training) and trunk strength for the untrained population that should contribute to general health and functionality.
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.
A criteria based progression rehabilitation protocol for hamstring strain injuries presented at the Sports Medicine Australia conference 2015 during the Hamstring symposium
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.
Lower limb alignment in young female athletes is associated with knee joint m...peertechzpublication
Background: Increased rotational forces and knee valgus forces puts strain on the anterior cruciate
ligament, frequently ruptured in female athletes. Increased internal hip rotation and increased knee valgus
alignment, possible risk factors for anterior cruciate ligament rupture, are more common in women than
men.
Bryan Heiderscheit
Professor, Department of Orthopedics and Rehabilitation, Department of Biomedical Engineering, Director, UW Runners' Clinic, Director, Badger Athletic Performance Research, Co-director, UW Neuromuscular Biomechanics Lab, University of Wisconsin-Madison, Madison, WI, USA.
-
Hamstrings are most susceptible to injury during the early stance phase of sprinting
(13th October, Barcelona)
6th MuscleTech Network Workshop
Comparison between Hamstring Lengthening Tendon and Hamstring Tendon Transfer...Service_supportAssignment
Cerebral Palsy (CP) is defined as a non-progressive brain lesion and has many disorders that may affect both movement and posture (Bobath 1991). Spastic cerebral palsy influence 70% of child population with CP and happen when white matter tracks damage between the cortex and the spinal cord. Moreover, a main problem for children with spastic CP is their feet and leg muscles, which might shorten or tighten around certain joints (Bjorklund 2006). C
Ágape Design e Propaganda
Somos uma agência de design e propaganda situada na cidade de Londrina. Focamos no design estratégico visando resultados positivos para seu produto ou marca.
O design é uma peça fundamental para o desenvolvimento de sua empresa, por meio dele é possível entender qual o atual posicionamento e imagem percebida da sua empresa diante dos clientes, funcionários e concorrentes, e com estratégia e criatividade buscar destaque e inovação no mercado.
Pensar design não é somente pensar na estética da sua imagem, mas principalmente na funcionalidade da mesma. Buscar um posicionamento estratégico, uma linguagem que o público identifique e o mais importante, a satisfação e o desejo dos seus clientes.
This a sample of a creative look I developed for the Christmas flyers for Canadian Tire. Each year the creative look changes including typography and photography direction. Being involved in branding, creating looks consistent across various mediums is key to producing a product that customers can identify with quickly.
Mechanics of the human hamstring muscles during sprintingFernando Farias
As peak musculotendon
force and strain for BF
LH
, ST, and SM occurred around the same time during terminal swing, it is suggested that this period in the
stride cycle may be when the biarticular hamstrings are at greatest injury risk. On this basis, hamstring injury prevention or rehabilitation
programs should preferentially target strengthening exercises that involve eccentric contractions performed with high loads at longer
musculotendon lengths.
Effects of a six week hip thrust versus front squatFernando Farias
Hip thrust training resulted in greater improvements in the isometric mid-thigh pull peak
force compared to squat training, even though the pull involved a vertical force vector. It is
proposed that this is due to the hip extension moment-angle curves of the squat versus that of the
hip thrust, in that the hip thrust likely has a greater hip extension moment requisite at the angle at
which the isometric mid-thigh pull is performed, but these joint-specific kinetic hypotheses
require further investigation.
Correlation between conventional clinical tests and a new movement assessment...Stavros Litsos
Correlation between conventional clinical tests and a new movement assessment battery - Bachelor thesis
Despite the complexity of movements performed in sports, physical examination is today done by conventional tests that evaluate joints and muscles individually (e.g. Smith press test, Figure1). Our study used a new movement assessment battery of 20 reach tests, which incorporates the complexity and diversity of natural human movements, taking into consideration that joints are interdependent in a movement and that the planes and sequences of a movement change during its performance. The purpose of this study was to determine whether or not there is a correlation between conventional mobility tests and the new assessment battery.
Clin Sports Med 23 (2004) 531–544Biomechanics and developmen.docxbartholomeocoombs
Clin Sports Med 23 (2004) 531–544
Biomechanics and development of the elbow in
the young throwing athlete
Mark R. Hutchinson, MD*, Shawn Wynn, MD
Sports Medicine and Human Performance Center, Department of Orthopaedics,
University of Illinois at Chicago, 270 MSB, M/C 844, 835 South Wolcott, Chicago, IL 60612, USA
Biomechanics is a complex study of function and demands, including struc-
ture, motor power and acceleration, and angular forces and loads. Regarding the
elbow, the study of biomechanics includes: the flexion/extension motion;
pronation/supination motion; motor power and acceleration related to the biceps,
brachialis, triceps, brachioradialis, supinator, and pronator teres muscles; struc-
tural shapes and interactions of the distal humerus/proximal radius/proximal ulna;
and the forces related to a variety of demands, ranging from lifting to throwing.
The biomechanics of throwing is particularly complex, and relies not only on the
function of an isolated segment such as the elbow, but on the performance and
function of an entire kinetic chain of segments, including the foot-ground surface,
hip and core power and rotation, scapular mobility and stability, shoulder motion
and function, and hand and wrist position at ball release. The throwing motion
has been studied in youth, adolescent, and adult pitchers at all levels of com-
petition [1–14]; however, most biomechanical studies have been performed
on the skeletally mature athlete, with closed physes, with years of throwing
experience, and usually involved in competition at some level. There is less
biomechanical information available on the developing child at different stages of
growth, physeal age, and throwing levels.
The complexity of the study of biomechanics is magnified in the skeletally
immature athlete, due to the dynamic changes occurring during the devel-
opmental phases of youth. The forces and torques of throwing with open physes
have been associated with adaptational changes in the growing bone. As long
bones lengthen with physeal growth, moment arms are altered, changing any
force calculation. The maturing neuromuscular system is progressing with in-
0278-5919/04/$ – see front matter D 2004 Elsevier Inc. All rights reserved.
doi:10.1016/j.csm.2004.06.005
* Corresponding author.
E-mail address: [email protected] (M.R. Hutchinson).
M.R. Hutchinson, S. Wynn / Clin Sports Med 23 (2004) 531–544532
creased muscle mass and power. The pace of muscular maturation mirrors, but is
not directly correlated to, advancing maturity of the neurologic system that
controls coordination, proprioception, quickness, and control. Each segment of
the kinetic chain matures at a different pace, requiring the young thrower to make
continuous, subconscious modifications to account for the changes and still
successfully perform the task or demand. Indeed, although young throwers may
develop the normal sequence of throwing—including windup, cocking, accel-
er.
1. INVESTIGATING THE SEATED DOUBLE POLING CYCLE: IDENTIFYING
BASELINE MEASURES FOR THE PREPARATION PHASE
Alicia M Gal1
, Adrian DC Chan1
and Dean C Hay2
Ottawa-Carleton Institute for Biomedical Engineering, Carleton University,
Ottawa, Canada1
School of Physical and Health Education, Nipissing University, North Bay,
Canada2
The purpose of this study was to identify baseline measures (BM) for the preparation
phase (PREP) within the linear stroking cycle for the sport of sledge hockey. The addition
of this phase to seated double poling is unclear biomechanically; full arm extension to
pick-plant. A validated solid-static prototype mimicking the average single-armed adult
male with dynamic shoulder joint was used to determine BM in 3 dimensions and initial
pick-impact forces (GRF). Results indicated that average peak GRF occurred prior to
5.0x10-3
s post initial contact; Fy=179N, Fz=515N and Fx=573N. Evidence indicated PREP
should initiate slightly below the horizon in order to produce the greatest non-contracting
force for sledge propulsion. Isolated data provides insight to the biomechanics of the
dynamic limb within PREP assisting with its importance to the complete cycle.
KEY WORDS: sledge hockey, stroking cycle, impact forces
INTRODUCTION: The shoulder joint’s natural architecture produces the largest range of
motion (RoM) within the human body; in order to achieve this RoM mechanical design
warranted a reduction in the joint’s structural integrity throughout 3-dimensions (Veeger &
van der Helm, 2007). As a ball-and-socket joint this heightened level of mobility creates
diminished confidence in the joint’s ability to produce load-bearing stability, unlike the hip
joint whose architectural design promotes structural compliancy through maximal load-
bearing mobility (Veeger & van der Helm, 2007). Paralympic sledge hockey (male seated
para-hockey) is a high-velocity high-impact sport dependent upon the shoulder joint’s
structural integrity in two ways: 1) the nature of the sport sanctions full body-contact were the
shoulder joint, the most prominent exterior point of contact, is constrained to withstand and
absorb the impact forces from an oncoming opponent 2) locomotion is produced solely from
the shoulder joint in a double poling fashion where speed and quickness are dependent upon
force-duration impact cycles. In addition to these simplified biomehanics of the sport,
participants are commonly but not mandated to be considered within the shoulder-dependent
daily-living special population (wheelchair or crutch-assisted). Therefore, trauma to the
shoulder joint is inevitable for these athletes, however, scientific evidence can improve
muscular training focuses, rehabilitation and provide advancement concerning sport-specific
tasks.
Double poling has been investigated and determined to consist of two phases commonly
known as: 1) propulsion the contact phase of the pole's pick with the terrain; pick-plant to
pick-off, and 2) recovery the return phase of the cycle; no direct contact with the terrain
(Holmberg et al., 2007). Seated double poling investigations suggest an additional third
phase known as preparation; from full arm extension to pick-plant for a short pole length
seen in such sports as sledge hockey and alpine sit-skiing or from pick-off to initiation of
return to the forward cycle in sports such as cross country sit-skiing involving longer pole
lengths (Lomond & Wiseman, 2003; Bernardi et al., 2013). The addition of this phase has
been suggested due to observable changes within sledge movement and biomechanical
parameter trends (Bernardi et al., 2013). However, the direct biomechanical benefit to the
addition of this phase into the complete cycle is currently unknown warranting investigation.
This study investigated and determined baseline measures for preparation in the sport of
sledge hockey using a validated anatomically correct solid-static average adult single-armed
2. male prototype, where the shoulder joint was the only dynamic component; and a 3-
dimensional motion capture system with force-plate. Obtaining baseline measures for
external forces concerning the upper limb throughout this downward movement allows for
comparison against internal forces either supporting or dismissing the assumptions required
to be made when investigating dynamic movement. Baseline measures will also provide
insight to the dynamic limb's contribution to the phase in turn the phase's overall importance
to the complete cycle. The purpose of this study was to identify baseline measures for the
preparation phase within the linear stroking cycle for the sport of sledge hockey.
METHODS: A previously validated methodology to investigate baseline measures for the
preparation phase within the linear stroking cycle for the sport of sledge hockey was used. A
solid-static prototype architecturally designed from US Marine Corp personnel data and
previously determined parameters for segment shape, length and mass was built to
represent a single armed average adult male weighing 80kg with dynamic shoulder joint. The
prototype was used in conjunction with a Vicon motion capture system and Kistler force-plate
to investigate the preparation phase of this forward stroking cycle; downward movement and
contact force; data were collected at 200Hz and 800Hz respectively. The prototype was
fastened to a sledge hockey sledge with fixed hip angle equaling 40o
from the horizon and
weights placed in the bucket to off-set the balance allowing free stance. A velcro strap was
attached to the forearm’s centre-of-gravity (CoG) and raised to where the neck would be
located testing shoulder start angles at +10o
, 0o
and -10o
from the horizon; then released
allowing the arm to drop down and pick to contact the force plate. Two plastic washers
4.00cm in diameter were used to decrease friction at the dynamic joint. Two 1.30kg wrist-
weights were attached to the upper arm in a stretched out fashion (lateral and medial) with
an overlap at CoG mimicking arm morphology. A 1.20kg ankle-weight was attached to the
lateral forearm in a stretched out fashion (Fig 1). Markers were placed at the joint-centre for
the shoulder and elbow, upper arm CoG, forearm CoG, anterior wrist, posterior wrist, and
blade, joint and pick of the stick. Additional markers were used to construct the torso and
indicate the left superior anterior and posterior hip; markers were 14mm in diameter. Three
useable trials investigating fixed joint angle combinations at the elbow 120o
, 135o
and 150o
,
and wrist-stick at 45o
were acquired and processed using MATLab code for both trajectory
and the force plate data; zero-lag fourth-order Butterworth lowpass filter at 12Hz and zero-lag
second-order Butterworth highpass filter at 4Hz, respectively. Kinematic and kinetic data
were collected and time-normalized allowing for comparison; pre contact to the initiation of
stick recoil. A mathematical model was developed and used as a control for validation
purposes.
RESULTS: Trajectory data illustrated similar curvature for all respective elbow angles
showing an increase in arc-slope as the elbow angle decreased; similar to shortening the
radius of a pendulum (Fig 2). On average the pick vertically displaced 0.55m, 0.52m, 0.60m
for a 120o
, 135o
and 150o
elbow angle, respectively. Further investigation regarding elbow-
pick-plant angle is currently being conducted. Point of rotation was also evaluated and
labelled as a local origin; the shoulder (Fig 2). Results indicated that average peak impact
reaction forces occurred prior to 5.0x10-3
s post initial contact and were 178.5N, 514.8N and
572.9N, mediolateral, vertical and horizontal respectively (Fig 3a). Reaction forces have a
negative orientation within their respected illustrations to assist with a visual connection to an
increasing force (more negative) from a downward motion. Again, as seen in the validation
evidence horizontal reaction force on average was greatest producing 572.9N of reaction
force onto the shoulder compared to 491.6N average vertical reaction force (Fig 3b); the
mathematical model indicated that vertical reaction force was to be dominant. Average
vertical reaction forces also indicated that the lower the start angle the greater the reaction
force 273.7N, 553.9N and 716.9N for +10o
, 0o
and -10o
, respectfully (Fig 3b).
3. DISCUSSION: Baseline measures concerning external forces allows for comparison against
the necessary assumptions made regarding internal forces within the human body during
dynamic movement. Understanding baseline measures concerning the upper limb in this
downward moving phase of the cycle will provide an evaluation tool used in subsequent
research comparing musculoskeletal produced shoulder dependent locomotion in the sport
of sledge hockey. Since the prototype had a fixed hip angle similarities or differences
between baseline measures and musculoskeletal data isolated to the dynamic limb can be
determined. This isolated data will provide insight to the biomechanics of the limb movement
within the phase in turn its importance to the complete cycle. Additionally, further
investigation concerning hip flexion-extension in conjunction with limb movement can be
conducted; static torso trajectory compared to dynamic torso trajectory from musculoskeletal
produced locomotion. From this baseline evidence preparation initiation should begin slightly
below the horizon in order to produce the greatest non-contracting force to propel the sledge
(Fig 3). Further investigation regarding pick-plant angle is currently being conducted to assist
with understanding elbow flexion-extension throughout the phase; providing sport-specific
evidence promoting maximal force transfer to produce sledge propulsion.
Combing this baseline data with musculoskeletal produced data a completed illustration of
the linear stroking cycle will be created outlining phase duration, muscular contributions
within each phase, parameter biomechanical trends, and key components such as peak
impact forces, peak reaction forces, pick-plant and pick-off. The cumulative goal for this
research is to provide a definition for shoulder produced gait similar to that which currently
exists for hip produced gait. In turn a sport in much need of scientific evidence will gain a
completed understanding of how locomotion is produced and how to enhance athletic
performance. Additionally upon completion, this research will provide shoulder-dependent
daily-living populations a heightened understanding of shoulder produced gait allowing for
advancement in muscular training and rehabilitation. Shoulder produced gait occurs in a
forward cyclical motion similar to the linear stroking cycle see in sports such as sledge
hockey; wheelchair propulsion and crutch assist locomotion. Understanding weight-bearing
shoulder produced gait will reduce the risk of overloading this highly mobile joint in turn
reinforcing structural integrity.
CONCLUSION: In conclusion this study has determined baseline measures for the
preparation phase within the linear stroking cycle seen within the sport of sledge hockey.
These baseline measures will be combined with musculoskeletal data in order to determine
the biomechanical importance of preparation to the complete cycle. This evidence will be
combined and illustrated from static-start to momentum driven cycles providing sledge
hockey advancement in a necessary but basic skillset; the linear stroking cycle.
Figure 1: Illustration of the validated solid-static prototype used to determine baseline
measures for the preparation phase within the sport of sledge hockey (not test position).
4. Figure 2: Average vertical marker trajectories for the pick, wrist and elbow during all trials. The
shoulder origin is provided for reference. Blue 150o
; Green 135o
; Red 120o
elbow angles; line
+10o
; --- 0o
; … -10o
start angles.
Figure 3a: Average vertical reaction forces from initial pick-impact. Blue Mediolateral; Green
Horizontal; Red Vertical. 3b: Average reaction forces from initial pick-plant time-normalized.
Blue +10o
; Green 0o
; Red -10o
start angles; Black --- average.
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Acknowledgement
M. Lamontagne (Human Movement Biomechanics Laboratory), B. Hallgrimsson (Industrial
Design) and M. Haefele (Research Assistant)