- The study examined the effects of gastrocnemius (calf muscle) fatigue on ankle joint kinetics during the squat jump in 5 trained male basketball players.
- Participants performed squat jumps before and after a calf raise protocol to induce gastrocnemius fatigue. Kinematic and kinetic data of the foot segment was analyzed.
- Results showed no significant difference in foot segment power between pre- and post-fatigue jumps, indicating that bi-articular muscle fatigue did not reduce segmental kinetics.
- The conclusion is that the gastrocnemius acts to transfer energy between segments rather than generate work, so its fatigue did not decrease ankle joint power during the squat jump.
Effects of various types of lifting like stoop lifting, squat lifting, semi-squat lifting on the body and also when to use which type of lift to help prevent or minimize the risk of musculoskeletal injury.
This presentation describes the biomechanical basis for the expression of muscular strength and power. In it you will learn to calculate force, work, and power. You will then learn how building strength improves power and performance in sport. Finally, we will take this information and apply it to training and sports.
Effects of various types of lifting like stoop lifting, squat lifting, semi-squat lifting on the body and also when to use which type of lift to help prevent or minimize the risk of musculoskeletal injury.
This presentation describes the biomechanical basis for the expression of muscular strength and power. In it you will learn to calculate force, work, and power. You will then learn how building strength improves power and performance in sport. Finally, we will take this information and apply it to training and sports.
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.
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.
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.
1. Does Bi-articular muscle fatigue result in a
decrease in ankle joint extension kinetics in the
squat jump?
Daniel Yazbek
ABSTRACT
Purpose: Compare the foot segment kinetics in the squat jump before and after Gastrocnemius
fatigue. Methods: 5 healthy trained male basketball players (age 20-22) performed maximal squat
jumps before and after standing calf raises. Each subject performed 8 sets of 12 calf raises with 45
seconds rest between sets with a load of 75% Of 1RM. Jumping motion was captured using one high
speed pentax fastcam PCI R2 Photron at 125 Hz. Kinematic and kinetic data was expressed as thigh,
leg, and foot to determine angular velocity, moment and power. Results: There was no significant
difference between foot segment power after gastrocnemius fatigue (0.182 > .05) as indicated through
a paired samples t-test using SPSS data analysis. Conclusion: Bi-articular muscle fatigue does not
reduce segmental kinetics as there role is to transfer energy in a proximal-distal sequence pattern,
rather than generate work.
Keywords: Bi-articular, energy-transfer, fatigue, work
Introduction: The squat jump requires
maximal extension power of the hip, knee
and ankle. The gastrocnemius is regarded
as a powerful plantar flexor of the foot and
it would be expected that fatigue of this
muscle would compromise the explosive
power of a squat jump. Athletes must be
able to achieve maximal height with each
jump despite muscular fatigue
Our study aims to identify the differences
in the magnitude of foot angular velocity,
moment and power before and after
fatigue of the gastrocnemius, when
performing a squat jump.
There has not been a study examining the
direct effects on bi-articular muscle fatigue
on performance. However, there have
been studies in which mono and bi-
articular muscles have been examined, in
order to understand there functions in
movement and there have been studies
regarding the effects of muscle fatigue on
performance.
However, the effects of muscle fatigue
were examined in muscles which mostly
involved mono-articular muscles.
Our study aims to bring both variables
within the context. Therefore our study
aims to address the following question. If
Bi-articular muscles do not undergo a
significant change in muscle length and if
work is defined as force acting over a
distance, then bi-articular muscles that are
fatigued should not contribute to
decreased segment work or power?
Overall, we hypothesize that ankle joint
plantar flexion velocity, moment and
power will not be significantly different
after the fatiguing protocol.
Literature review: The squat jump is an
essential athletic component that is
performed by many athletes in a variety of
sports such as basketball and high jump
(Stone et al, 2003). The summation of
work and power of the muscles crossing
joints and the amount of energy
2. transferred from proximal to distal
segments is critical to translating angular
momentum into upward linear momentum
of the bodies’ centre of mass (Scehnau &
Bobbert, 1987).
It has been shown that muscles that span
across one joint, generate work and cause
rotation about its joint axis and in doing so,
transfer energy to the more distal
segments through the two joint muscles
(Schenau, Jacobs & Bobbert, 1996).
In a study by Barret & Neal (2001), the
major source of work generated during the
vertical jump was 92-94%. The mono-
articular hip and knee extensors, gluteus
Maximus and vastus intermedius
respectively, were shown to play a large
role in terms of work generation and
contributed to 80% of the total work done
by the muscle tendon units. Conversely,
Bi-articular muscles rectus femoris
hamstrings and gastrocnemius generated
relatively little work themselves but played
a role in transferring mechanical energy
between joints. The amount of energy
transferred between joints via biarticular
muscles was between 11-29%.
Additionally, an analysis of the lower
extremity during a full squat showed that
the gastrocnemius was heavily recruited
but performed no positive work because it
was contracting eccentrically and could
have been involved with transferring
energy distally due to its bi-articular nature
(Robertson, Wilson & Pierre, 2008).
However, the conclusions for this study
were not specific to a countermovement
jump nor did it employ a fatiguing protocol
to the gastrocnemius.
It is clear that muscle fatigue causes a
decrement in jumping performance which
was shown by Toumi et al (2006), in which
maximal concentric power and muscle-
tendon stiffness was reduced in the squat
jump following isometric leg press fatigue
and drop jump stretch shortening
repetitions till fatigue. Ground contact time
was increased equally following both
fatiguing protocols. However, in this study,
the fatiguing protocols did not isolate the
bi-articular muscles from the mono-
articular muscles, which if it did might
have resulted in a different conclusion due
to their differing functions.
JI et al, (2000) studied the effect of cycling
induced fatigue on joint power in the squat
jump. The fatigue protocol consisted of
one interval of 30 second pedalling on a
monark cycle at a load of 0.075kg per one
kilo of bodyweight. There was a significant
reduction in knee joint power after fatigue.
However, there was a smaller reduction of
Hip and ankle joint power compared to
knee joint power after fatigue. This study
did not explain why a reduction in fatigue
affected knee joint power rather than the
hip or ankle, nor did it fatigue just the two
joint muscles.
In another study, Tomioka, Owings &
Grabiner (2001), showed that lower
extremity coordination may be more of a
factor in contributing to maximal jump
height than lower extremity strength and
that maximal vertical jump can be
diminished by altered hip-knee
coordination. It is not known however if
fatigue of the gastrocnemius might alter
the hip-knee angle coordination and
consequently affect the jump performance.
3. Methods:Participants of 20-21 years (5
male), volunteered to be involved in the
study.
Protocol - Markers were placed on the
the lateral malleolus and the 5th
metatarsal
of the foot. This placement of markers
defined the foot segment. The participant
performed a counter movement jump with
arms crossed across the chest. The
angular velocity, moment and power were
calculated.
Following the jump, subjects performed 8
sets of 12 repetition calf raises using a
load of 75% of their 1RM on a 35cm step.
The subject would rest 45 seconds before
continuing the next set, for a total of 8
sets. To ensure the gastrocnemius was
under large fatigue, a standing calf raise
jump was performed before and at the
start of fatigue protocol. Failure of the toes
to clear the ground compared to
successful clearance of the toes at the
start of the protocol indicated muscle
fatigue. Following this, a second
countermovement jump was immediately
performed.
Segment angle was defined as the
horizontal line from the distal joint axis and
the line intersecting the segment parallel,
above that joint.
Power was calculated from foot moment
and foot angular velocity
Schematic model:
Results:
-20
-15
-10
-5
0
5
10
15
1
7
13
19
25
31
37
43
49
55
61
67
73
79
85
91
97
pre
post
Figure 2: An exampleofone participant ofthe anklejoint plantar flexionpowerversustime, during theascending phase of
the vertical squat jump. The Blueand red linesrepresentthesquat jump before and after fatiguerespectively. This datawas
resampled to comparemean segment power. The preand post foot segment power ofthejump was12.5 J.S-1. Net Plantar
flexion power wasdefined aspositiveand in theclockwisedirection. All preand post valuesfor participantswerenot
significantly different (0.182>0.05)
Foot segmentpower
Power (J.S-1
Time (frames / seconds) (125/s)
𝑃 = 𝑀 ∙ 𝜔
Figure 1: Modelofthe Hip,knee& ankle withrespectivethigh,leg & foot segments. The Gastrocnemiusisrepresented asthe
line joining thedistal posterior thigh to theposteriorplantar foot. Diagram on the left is
the descent phase and rightside istheascent phase ofthe
squat jump.
4. Although peak plantar flexion power was
not significantly different (0.182>0.05) in
the 5 subjects, this participant showed no
difference in peak plantar flexion power of
the squat jump. Peak foot segment power
was 12.5 J.S-1 before and after fatigue.
Discussion: Our results imply that the
gastrocnemius must have acted passively
to confine segment direction and
magnitude.
Maximal muscular fatigue of the bi-
articular gastrocnemius did not affect the
foot segment power during the squat
jump. It appears that our results do
support the mechanical function of bi-
articular muscles.
The gastrocnemius must have behaved
primarily as a segmental link between the
thigh and foot, rather than generate work,
in which it’s coupling action to plantar
flexion power, was dependent on the
muscles proximally, such as the one-joint
vasti and gluteus Maximus.
One flaw to this study is the failure to
induce a fatiguing protocol that is specific
to the speed of plantar flexion during the
squat jump. Had we incorporated
plyometric calf raises to the protocol,
perhaps the foot segment kinetics would
have changed. Further studies need to
address these effects.
Conclusion: Maximal muscle induced
fatigue to the gastrocnemius does not
decrease foot segment power during the
squat jump.
References:
Barret,R., & Neal,R. (2000). Energeticsof lowerextremitymovementspredictedusingan
EMG-Drivenmuscle model.InternationalSymposiumon Biomechanics.18:1-4.
JI, Q., JI, Z. & Liu,R. (2000).Joint power and its relationship to the fatigue of human body during
Vertical jumps.InternationalSymposiumon Biomechanics.18: 1-4.
Robertson,D.E.,Wilson,J.J.,&ST Pierre,T.A.(2008). Lowerextremityfunctions duringfull
squats.Journalof Applied Biomechanics.24: 333-339.
Stone, M.H., O’Bryant, H.S., McCoy, L., Coglianese,R., Lehmkuhl,M. & (2003). Power and maximum
strength relationships during performance ofdynamic and static weighted jumps. Journal ofstrength and
conditioning Research. 17(1):140-14.
Tomioka,M., Owings,T.M.,& Grabiner,M.D. (2001). Lower extremitystrengthand
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Biomechanics.17: 181-187.
Toumi,H, Pourmarat,G., Best,T.M., Martin,A.,Fairclough,J.,& Benjamin,M.(2006).
Fatigue andmuscle-tendonstiffnessafterstretch-shorteningcycle andisometricexercise.Applied
Physiology,Nutrition &Metabolism.31(5):565-572.
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individualmusclesduringexplosive legextensions:The role of Bi-articularmuscles. Journalof
Biomechanics.29(4): 513-523.
VanIngenSchenau,G.J.,Bobbert,M.F.& Rozendal,R.H.(1987). The unique actionof Bi-
articularmusclesincomplex movements. Journalof anatomy.155: 1-5.