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A Biomechanical Analysis of the Squat Between Competitive Collegiate, Competitive High School, and Novice Powerlifters

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The purpose of this study was to measure and analyze kinematic differences between competitive collegiate (CLG, n = 9) powerlifters, competitive high school (HS, n = 9) powerlifters, and novice (NV, n = 11) powerlifters during a maximal squat to determine the effect of skill level on performance. All powerlifters performed 3 squats, with the final squat being their 1 repetition maximum. Kinematic data (descent, ascent, total lift times, knee angle magnitude, knee angular velocity, and knee angular acceleration) was measured using 2-dimensional motion analysis equipment. Differences in mean peak kinematic values between the 3 groups were analyzed using a 1-way multivariate analysis of variance, p <or= 0.05. Differences were found between the NV and HS in the time to ascent, the total lift time, the normalized time to peak (NTTP) in knee angular velocity from the "sticking point" to the "lockout," and the NTTP in knee angular acceleration during the ascent. A difference was found between the CLG and HS in the peak knee angular velocity between the bottom of the lift and the sticking point. Differences were also found in the rate of acceleration upward after coming out of "the hole" between the CLG and NV and CLG and HS. A difference was found in the rate of peak deceleration upward to the sticking point between the CLG and NV. To avoid injury and to achieve optimum results in powerlifting, lifting technique must be optimized. The HS and NV accumulated several significant differences in NTTP during the ascending phase. However, the major finding between the 3 groups was in the rate of acceleration upward after coming out of the hole. Coaches should focus their training programs on increasing strength in unskilled powerlifters for the purpose of increasing acceleration from the bottom of the lift.
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ABIOMECHANICAL ANALYSIS OF THE SQUAT
BETWEEN COMPETITIVE COLLEGIATE,COMPETITIVE
HIGH SCHOOL,AND NOVICE POWERLIFTERS
WENDY M. MILETELLO,
1
JASON R. BEAM,AND ZACHARY C. COOPER
1
Department of Kinesiology, Louisiana Tech University, Ruston, Louisiana
ABSTRACT
Miletello, WM, Beam, JR, and Cooper, ZC. A biomechanical
analysis of the squat between competitive collegiate, competitive
high school, and novice powerlifters. JStrengthCondRes23(5):
1611–1617, 2009—The purpose of this study was to measure
and analyze kinematic differences between competitive colle-
giate (CLG, n= 9) powerlifters, competitive high school (HS, n=
9) powerlifters, and novice (NV, n= 11) powerlifters during
a maximal squat to determine the effect of skill level on perfor-
mance. All powerlifters performed 3 squats, with the final squat
being their 1 repetition maximum. Kinematic data (descent,
ascent, total lift times, knee angle magnitude, knee angular
velocity, and knee angular acceleration) was measured using
2-dimensional motion analysis equipment. Differences in mean
peak kinematic values between the 3 groups were analyzed
using a 1-way multivariate analysis of variance, p#0.05.
Differences were found between the NV and HS in the time to
ascent, the total lift time, the normalized time to peak (NTTP) in
knee angular velocity from the ‘‘sticking point’’ to the ‘‘lockout,’’
and the NTTP in knee angular acceleration during the ascent.
A difference was found between the CLG and HS in the peak
knee angular velocity between the bottom of the lift and the
sticking point. Differences were also found in the rate of
acceleration upward after coming out of ‘‘the hole’’ between the
CLG and NV and CLG and HS. A difference was found in the
rate of peak deceleration upward to the sticking point between
the CLG and NV. To avoid injury and to achieve optimum results
in powerlifting, lifting technique must be optimized. The HS and
NV accumulated several significant differences in NTTP during
the ascending phase. However, the major finding between the 3
groups was in the rate of acceleration upward after coming out of
the hole. Coaches should focus their training programs on
increasing strength in unskilled powerlifters for the purpose of
increasing acceleration from the bottom of the lift.
KEY WORDS powerlifting, biomechanics, technique, motion
analysis, skill level
INTRODUCTION
The squat is a powerful movement that measures an
individual’s lower body and trunk strength (5) and
is used in training programs of athletes from
various sports (2). Strength, power, and precision
are necessary for maximal performance when performing the
squat in competitive powerlifting competitions and as part of
a strength training regimen. Previous literature in the area of
powerlifting focuses on knee mechanics because an elevated
risk of injury to this area exists (3,10). Mechanical effec-
tiveness is related to an individual’s experience and can be
determined with a biomechanical analysis among groups
with different skill levels (4,8,9). Squat technique may deter-
mine victory in a powerlifting competition and may predis-
pose an athlete to injury. Therefore, providing knowledge of
the differences in technique due to skill level during the squat
may be useful. The purpose of this study was to measure and
analyze kinematic differences between competitive collegiate
(CLG) powerlifters, competitive high school (HS) power-
lifters, and novice (NV) powerlifters during a squat performed
at maximum weight for 1 repetition to determine the effect of
skill level on performance.
METHODS
Experimental Approach to the Problem
The purpose of the current study was to determine the effect
of skill level on performance of the squat in powerlifting.
Kinematic variables were chosen to measure the powerlifting
technique while performing the squat. Observation of the
kinematic variables was conducted at the knee joint and used
to quantify skill level among the groups: NV, HS, and CLG
powerlifters. Mechanical effectiveness may be determined by
observing timing, velocity, and accelerations of selected body
segments or joints.
Subjects
Nine competitive CLG powerlifters, 9 competitive HS
powerlifters, and 11 NV powerlifters participated in this
study. The mean mass, height, age, and years of experience of
Address correspondence to Jason Beam, jbeam@unm.edu.
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the powerlifters were recorded (Table 1). The CLGs were
considered elite with 1 male national champion, 5 national
champion runner-ups (4 women and 1 man), 3 male third
place national champions, 2 fifth place national champions (1
woman and 1 man), and 1 male seventh place national
champion at the U.S. Collegiate National Championships in
2006, Miami, FL. In addition, these powerlifters had 2 world
runner-ups, 1 third place winner, and 1 sixth place winner at
the world championships in 2005, Fort Wayne, IN. There
were 7 athletes who placed in the top 10 in the Louisiana
State High School Powerlifting Meet (3 men and 4 women),
5 who placed at a regional meet (2 men and 3 women), and
7 who placed in a district meet (2 men and 5 women) in
Louisiana in 2006. The NV had no more than 6 months of
experience at performing the squat. The University In-
stitutional Review Board at Louisiana Tech University in
Ruston, LA, approved this study. Written and informed
consent was obtained from each participant. In addition,
a parental approved informed consent was obtained from
each parent of the HS powerlifters.
Squat Procedure
The coaches of the CLG and HS powerlifters provided
approximate 1 repetition maximums (1RMs) of their athletes.
The NV powerlifters participated in a weight training
program for 10 weeks, and a powerlifting coach obtained
approximate 1RMs after the completion of the program. All
powerlifters performed the squat raw (without squat suits or
wraps) and barefoot. After a warm-up (repetitions at ,50% of
their 1RM), each participant performed 3 trials with the final
trial representing their 1RM. The bar (20 kg) was placed on
a squatting rack, which was on a wooden platform and
slightly anterior to a force plate. Each participant rested 10
minutes before each trial. A U.S.A. Powerlifting–Certified
Judge determined if each squat met the squat criteria of the
International Powerlifting Federation Technical Rules (11).
The judge determined which of the 3 trials constituted the
best trial and that trial was used for analysis.
Instrumentation
A 4-point wooden calibration frame was used for the camera
calibration. A 5-point spatial model was used with markers
placed on bony landmarks in the lower extremity: the greater
trochanter, the lateral epicondyle of the femur, the lateral
malleolus of the fibula, the calcaneous, and the fifth meta-
tarsal, respectively. Kinematic data were obtained using a
Panasonic PV-GS55 60 Hz Digital Camcorder (Secaucus, NJ)
and an optical capture system. The markers used in detecting
movement were point-sized markers with radii of approxi-
mately 1 cm. They were covered with reflective tape to
help detect movement using videographic principles. All data
were processed using the Peak Motus System version 8.5
(Vicon, Centennial, CO).
Frames were automatically
digitized (169–181 per trial)
for the powerlifters. Cubic
spline interpolation was used
to generate missing coordinates
of the markers, and a recursive
Butterworth Low-Pass Digital
Filter with a cutoff frequency of
6 Hz was used to filter the data.
After data smoothing, trans-
formed data were examined
for differences among the
groups. Kinematic data were
examined for prominent peaks
TABLE 1. Participant characteristics: CLG (n= 9) vs. HS (n= 9) vs. NV (n= 11).*
Variables
Mean 6SD
CLG HS NV
Age (y) 19.78 61.39 17.22 60.67 20.09 61.38
Experience (y) 3.00 61.42 2.00 61.25 ,0.50
Weight (kg) 77.42 621.85 66.50 611.81 74.71 611.61
*CLG = collegiate; HS = high school; NV = novice.
Figure 1. Knee angles.
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Squat and Skill Level
in the magnitude and timing of angular displacement,
velocity, and acceleration for the knee.
Data Collection and Analysis
The data analysis involved creating events within the
squatting phase to predict differences in squatting technique
within each phase. The squat was divided into 3 phases: (a)
the beginning of the lift to the bottom of the lift, (b) the
bottom of the lift to the ‘‘sticking point,’’ and (c) the sticking
point to the end of the lift. The phases were further termed
according to common terminology used in the sport of
powerlifting. The point from the beginning of the lift to the
bottom of the lift is termed the ‘‘controlled dive bomb.’’ The
bottom of the squat is also known as ‘‘the hole.’’ The act of
maximally contracting the musculature from the hole to the
sticking point, which is represented by the decrease in
velocity that occurs mid-ascent (9), is commonly referred to
as ‘‘firing out of the hole.’’ The final phase occurs from the
sticking point to the end of the
squat, and it is termed the
‘‘lockout.’’
The total lift time, the descent
time, and the ascent time were
calculated. These phases of the
squat were normalized to the
same time frame for all groups
and included 20 frames before
the descent was initiated and 20
frames after the ascent was
terminated. To normalize the
time of the descent, the differ-
ence between the time at the
bottom of the squat and the
time at the start of the squat was
determined. To normalize the
time of ascent, the difference
between the time at the end of the squat and the time at the
bottom of the squat was determined. Finally, to normalize
the total lift time, the difference between the time at the end of
the squat and the time at the start of the squat was determined.
The magnitude of knee angle, knee angular velocities, knee
angular accelerations, and their corresponding normalized
time to peak (NTTP) were considered for each predominant
peak in curve values. This resulted in 1 peak (P1A) in knee
angle, which was the minimum knee angle achieved (Figure 1).
Three peaks in knee angular velocity were found, with peak 1
(P1B) representing the peak in knee angular velocity during
the descent, peak 2 (P2B) representing the peak in knee
angular velocity during the ascent and before the sticking
point, and the third peak (P3B) representing the knee angular
velocity after the sticking point but before the lockout
(Figure 2).
Six peaks were found for knee angular acceleration, with peak
1 (P1C) representing the acceleration downward, peak 2 (P2C)
representing the deceleration
downward before the hole, peak
3 (P3C) representing accelera-
tion upward, peak 4 (P4C)
representing deceleration in the
upward direction to the sticking
point, peak 5 (P5C) representing
acceleration beyond the sticking
point, and peak 6 (P6C) repre-
senting the deceleration before
the lockout (Figure 3). The
NTTP for each of the peaks
was the difference between the
time of the peak and the time
the lift was started. Each NTTP
is denoted by NTTP#*, where #
is the corresponding number of
the peak and * is the corre-
sponding letter of the peak.
Figure 2. Knee angular velocities.
Figure 3. Knee angular accelerations.
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Statistical Analyses
To determine the effect of skill level on technique between the
NV, HS, and CLG powerlifters, a 1-way multivariate analysis
of variance was conducted on mean peak knee kinematic
values. Pairwise differences were analyzed using a Fisher’s
least significant difference. A mean strength quotient (SQ =
weight lifted [kg] 3body mass [kg]
21
) for the 3 groups was
analyzed in terms of mean and SDs for the purpose of data
interpretation.
RESULTS
The most important findings can be found in Tables 2 and 3
and Figures 4 and 5. Statistically significant differences were
found between the NV and HS in NTTP in knee angular
velocity from the sticking point to the lockout and the NTTP
in knee angular acceleration during the ascent. A statistically
significant difference was found between the CLG and HS in
the peak knee angular velocity between the bottom of the lift
and the sticking point. Statistically significant differences
were also found in the rate of acceleration upward after
coming out of the hole between the CLG and NV and the
CLG and HS. A statistically significant difference was found
in the rate of peak deceleration upward to the sticking point
between the CLG and NV.
The descent time, the ascent time, and the total lift time for
each group were analyzed for statistical significance. The NV
descended (1.53 60.31 seconds) faster than the CLG (1.61 6
0.50 seconds) and HS (1.77 60.34 seconds). The NV also
ascended (1.76 60.38 seconds) faster than the CLG (2.10 6
0.33 seconds) and HS (2.62 60.76 seconds). The NVs
completed their ascent and total lift (3.28 60.53 seconds)
significantly faster than the HSs completed their ascent and
total lift (4.38 60.88 seconds). The NVachieved the greatest
depth (66.17 67.44 °) at the bottom of the squat, with the
CLG not far behind (68.33 611.95 °). The HS achieved
the greatest knee angles (72.55 65.35 °) at the bottom of the
squat. An analysis was conducted on the strength quotient,
where the weight lifted to body mass relationship was
examined among the groups. CLG and HS mean and SDs
were compared (1.76 60.39 vs. 1.55 60.56) and resulted in
marginal differences. However, both CLG and NV and
(1.76 60.39 vs. 1.16 60.22) and HS and NV (1.55 60.56 vs.
1.1660.22) mean and SDs were compared and a large
difference existed.
TABLE 2. The peak knee angular velocities.*
Variable
Mean 6SD (°s
21
)
CLG High school NV Combined
P1B 2133.16 631.17 2149.02 626.86 2139.47 629.06 2140.48 628.75
P2B 101.57 637.1376.88 626.60 73.50 614.1483.26 628.73
P3B 152.77 626.37 169.70 664.52 182.38 638.33 169.26 645.47
*CLG = collegiate; NV = novice.
Significant difference (p,0.05) between P2B of the CLG and NV powerlifters.
TABLE 3. Normalized time to achieve peak knee angular velocities.*
Variable
Mean 6SD (s)
Collegiate HS NV Combined
NTTP1B 0.46 60.38 0.43 60.18 0.29 60.14 0.39 60.25
NTTP2B 2.08 60.38 2.14 60.36 1.92 60.40 2.04 60.44
NTTP3B 3.44 60.75 3.95 60.812.81 60.433.44 60.82
*HS = high school; NTTP = normalized time to peak; NV = novice.
Significant difference (p,0.01) between NTTP3B of the HS and NV powerlifters.
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DISCUSSION
The rate and timing of acceleration values were the key
kinematic variables in determining the effect of skill level on
technique during the descent. In particular, the rate and
timing of peak acceleration values may indicate how the
movement was controlled. In powerlifting, lower rates of
acceleration are desirable during the descent and higher rates
of acceleration are desirable during the ascent. The CLG
maintained the most control during the descent with overall
smaller acceleration values when compared with the HS. The
CLG strength quotient was the largest (weight lifted/body
mass), yet the group exhibited the most control during the
descent. The HS ranked third in terms of control of
movement during the descent. This may be attributed to
a larger strength quotient than the NV, yet less skill than
the CLG. Interestingly, the NV had the lowest rate
of deceleration before the hole. This may be attributed
more to their lower strength quotient rather than a higher
skill level.
The most significant finding of this study was the difference
in acceleration values among the groups during the ascent. A
higher skill level was best demonstrated by a higher rate of
acceleration after coming out of the hole and before the
sticking point. Powerlifters typically refer to this phenomenon
as firing out of the hole. Interestingly, all groups achieved their
highest rate of acceleration when firing out of the hole with
similar timing (0.10 seconds). The CLG ascended at a higher
velocity and achieved this velocity closer to the sticking point
when compared with the other groups. Overall, CLG had the
highest velocity and acceleration during this phase of the
movement. In addition, they spent the most time in this phase
of the movement. Therefore, the effect of skill level on
performance is most evident during this phase of the
movement.
The NV lacked control when terminating the movement
with a higher rate of acceleration to the lockout. The effect of
skill level on technique was less pronounced after the sticking
point. Overall, the HS spent more time performing the squat
than the other groups, especially during the ascent. This may
be explained by a larger strength quotient compared with the
NV but less skill compared with the CLG.
The current study revealed that patterns of performance
differ among groups with different skill levels. McLaughlin
et al. (9) substantiated these patterns in prior research. The
authors proposed that a model of performance of highly and
less skilled powerlifters should be determined to have a better
understanding on how to maximize performance for
competition and to determine ‘‘typical’’ errors for various
skill levels for improved safety. These authors compared elite
powerlifters (ranked with a top 10 performance in the world)
to highly skilled powerlifters (competing at a world-class
level, but not ranked with a top 10 performance). After an
extensive analysis of kinematic performance factors, vertical
bar velocity exhibited similar patterns among the group
Figure 4. Graphical analysis of the peak knee angular accelerations.
a
Significant difference (p,0.05) between P3C of the collegiate (CLG)
and high school powerlifters.
b
Significant difference (p,0.01) between
P3C of the CLG and novice (NV) powerlifters.
*
Significant difference (p,
0.05) between P4C of the CLG and NV powerlifters.
Figure 5. Graphical analysis of normalized time to achieve peak
accelerations.
*
Significant difference (p,0.05) between NTTP4C of the
high school (HS) and novice (NV) powerlifters.
**
Significant difference
(p,0.01) between NTTP5C of the HS and NV powerlifters.
***
Significant
difference (p,0.01) between NTTP6C of the HS and NV powerlifters.
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regardless of weight lifted. Furthermore, vertical bar velocity
also represented the effect of muscular force exerted by the
athlete on the bar (i.e., the end result). Vertical bar velocity
was indicative of subject technique and therefore was
considered the most meaningful parameter regarding
performance. The results found for the less skilled group
were higher vertical bar velocities and greater trunk lean on
descent. The group with less skill approached the lowest
position faster, and they also exhibited a lower bar velocity on
ascent when compared with the elite group.
In the current research project, findings were similar with
a faster descent and a slower ascent for the group with less
skill (i.e., HS). However, the knee joint angular velocity for the
descent and ascent was examined, rather than vertical bar
velocity. In addition, McLaughlin et al. (9) found that trunk,
hip, and knee horizontal displacements were greater in the
less skilled group. In the current research, relative knee
angular displacement was considered, and the less skilled
group had a greater knee angular displacement when
compared with the highly skilled group.
Biomechanical analysis of the knee joint during power-
lifting maneuvers has been conducted due to the incidence of
injury (4,6,7,10). For the younger and inexperienced athletes
(less than 1 year of training), the knee joint is the site with the
second most incidences of injury and pain, not only during
workouts but also immediately after and between workouts
(1). In previous literature, bar acceleration values were used
to assess differences between groups of varying skill levels
(4,5). Escamilla et al. (5) related bar acceleration information
to acceleration and force values for the knee and hip. A
greater deceleration magnitude for the bar was associated
with greater tibiofemoral shear and compressive forces
during the descent. In the current study, knee angular
accelerations varied between the groups. High school
athletes had acceleration values greater in magnitude when
compared with CLG athletes during the descent phase. The
results of the current study are similar to McLaughlin et al.
(9) and Escamilla et al. (5), where greater accelerations of the
bar occurred for the less skilled group during the descent
phase. Escamilla (4) also determined the rate of increase in
compressive forces during knee flexion and found that
compressive forces are higher when the knee flexion angle
was larger. As the knee flexion angle decreased to a smaller
value, a lower magnitude of knee compressive force was
found. In the current study, the less skilled athletes had larger
knee angles during the squat, which over long periods of time
of heavy training could be problematic.
Possible explanations for a more effective performance
among the CLG athletes may include the developmental
aspects of the athlete. The age of the athlete is directly related
to their anatomical and physiological development. In
addition, technical maturity of the athlete improves with
the more years of training (8). The HS powerlifters in the
current study were from many programs in the state of
Louisiana and therefore represented a variety of training
programs. The type of training program may be a factor that
should be controlled for in subsequent research. Many
questions still exist regarding differences in technique among
athletes with different skill levels in powerlifting. More
research on technical errors, which occur more often in less
skilled powerlifters, is needed to help coaches teach their
athletes how to properly perform the powerlifting squat.
Therefore, injuries may be reduced and performance may
improve.
PRACTICAL APPLICATIONS
When coaching unskilled athletes, coaches should be aware
that these athletes may not have a controlled descent when
compared with more skilled athletes. The coaches should
focus their training programs on timing of movement during
the descent and ascent. Another concern for coaches is
the ability of the athlete to accelerate from the bottom of
the lift or ‘‘fire out of the hole.’’ Coaches should focus
their training programs on increasing strength for the
purpose of increasing acceleration from the bottom of the
lift in unskilled powerlifters. Powerlifters of lower skill level
may have the tendency to end the lift with high rates of
acceleration or not to control the termination of their
lift. Coaches should be aware of the detrimental effects of
terminating a lift with high rates of acceleration on the knee
joints and should train lifters of lower skill levels to control
the lift when approaching a fully extended knee joint. In
addition, coaches should teach athletes lifting with heavier
weights to improve speed of movement through sport-
specific power training. This study provided data that
revealed that NV powerlifters had the tendency to drop too
low, which may have detrimental effects on the knee joints
due to an increase in sheer forces at the knee. Conversely, the
HS powerlifters were not dropping low enough and should
be taught to drop lower. Because dropping too low or not
dropping low enough when performing a squat may lead to
a less than optimal length-tension relationship, coaches
should train powerlifters to optimize the length-tension
relationship.
REFERENCES
1. Brown, EW and Kimball, RG. Medical history associated with
adolescent powerlifting. Pediatrics 72: 636–644, 1983.
2. Chandler, J and Stone, M. The squat exercise in athletic
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3. Chandler, J, Wilson, D, and Stone, M. The effect of the squat exercise
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Med Sci Sports Exerc 33: 127–141, 2001.
5. Escamilla, RF, Fleisig, GS, Lowry, TM, Barrentine, SW, and
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6. Escamilla, RF, Fleisig, GS, Zheng, N, Lander, JE, Barrentine, SW,
Andrews, JR, Bergemann, BW, and Moorman, CT III. Effects of
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9. Mclaughlin, TM, Dillman, CJ, and Lardner, TJ.
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... Thus, the reputation of powerlifting as a risky sport may be exaggerated and based on gut feelings rather than empirical data. In powerlifting, novice practitioners have increased risk of injury likely due to shorter experience, poorer lifting technique, and less adapted connective tissue and joints [18]. ...
... One study [18] analysed the biomechanics and technique in squatting; another [23] in bench press, and another [24] in deadlift. The other two studies [25,26] provided tools to evaluate a correct technical execution ( Table 1). ...
... The sumo deadlift compared with the conventional deadlift seemed to generate 25-40% less work, which may be a strategy to reduce injury of the low back [24]. During the squat, novice powerlifters performed both eccentric and concentric phases faster, which was suggested to be one of the causes of knee pain and injuries [18]. The use of bench shirts (very tight compressive/supportive shirts made of slightly elastic and very strong material that allow people wearing them to bench press significantly more weight via the shirt's elastic recoil) during the bench press promoted a less vertical path, less total work and less load on the shoulders, and may therefore be a strategy to reduce the stress on the shoulder joint [23]. ...
Article
Objective While powerlifting is a popular sport, there may be some safety concerns due to the repeated high loads. This literature review focuses on injury rates, areas of injury and biomechanical movement analysis. Method “Powerlifting” and “injury” were used in the most relevant databases. Inclusion and exclusion criteria were applied and 11 studies were included separated in three different categories. Results Based on 11 studies with a total of 763 lifters, the injury incidence in powerlifting is low; between 1.0–4.4 per 1000 hours, with the low back, shoulders and knees being the most affected areas. Lifting biomechanics were different between novice and elite lifters. Conclusion Evaluation of lifting technique and athlete characteristics may be a viable strategy to prevent acute or overuse pain and injury. During the main lifts, compressive/supportive apparel could be protective for lifters on this risk areas.
... It may increase the pressure on the anterior cruciate ligament and increase the risk of knee injury [41,42]. However, this phenomenon was not observed during H-SQ, which may be because the technical maturity and the neural mechanism of controlling movements of the novice are different from those of those with training experience when performing F-SQ movements with a larger range of movements because novices seem to prefer to lift with high acceleration while neglecting the control of movements [43,44]. However, this phenomenon cannot be further analyzed by existing evidence, as it is not the purpose of this study and will be further investigated in the future. ...
... However, in this study, the extension moment of the hip joint and knee joint appeared between 50% and 60% of the action cycle, i.e., the moment of lifting after squatting to the deepest point, and the extension moment of hip and ankle joint and the abduction moment of hip joint and knee joint of F-SQ were significantly higher than that of H-SQ at the moment of getting up. This may be because novice women in the squat lift moment there will be a greater instantaneous acceleration to complete the action and reduce the sense of control of the action [44], and when F-SQ to the deepest, the thigh and calf contact may produce a moment in the same direction as the quadriceps femoris, thus reducing the knee extension moment of the knee [5]. Therefore, compared with F-SQ, novice women have significantly smaller joint torque during H-SQ, which may indicate that novice women have better control of movement and a lower risk of injury during H-SQ. ...
Article
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Background: Females with different practice experience may show different body postures and movement patterns while squatting in different depths, which may lead to changes of biomechanical loadings and increase the risks of injuries. Methods: Sixteen novice female participants without squat training experience participated in this study. A 3D motion capture system was used to collect the marker trajectory and ground reaction force data during bodyweight squatting in different depths. The participants' kinematic data and joint moment were calculated using OpenSim's inverse kinematics and inverse dynamics algorithm. In this study, authors adapted a model especially developed for squatting and customized the knee joint with extra Degree-of-Freedom (DoF) in the coronal and horizontal plane with adduction/abduction and internal/external rotation. A paired-sample t-test was used to analyze the difference of joint range of motions (ROM) and peak moments between full-squat (F-SQ) and half-squat (H-SQ). One-Dimensional Statistical Parametric Mapping (SPM1D) is used to analyze the difference of joint angle and moment between the process of squatting F-SQ and H-SQ. Results: (1) Compared with H-SQ, F-SQ showed larger ROM in sagittal, coronal, and transverse planes (p < 0.05). (2) SPM1D found that the difference in joint angles and joint moments between F-SQ and H-SQ was mainly concentrated in the mid-stance during squatting, which suggested the difference is greatly pronounced during deeper squat. (3) Peak hip extension moment, knee extension moment, hip adduction moment, and plantar flexion moment of F-SQ were significantly higher than H-SQ (p < 0.05). (4) Difference of hip and knee extension moments and rotation moments between the F-SQ and H-SQ were exhibited during descending and ascending. Conclusions: The study found that novice women had larger range of joint motion during the F-SQ than H-SQ group, and knee valgus was observed during squatting to the deepest point. Greater joint moment was found during F-SQ and reached a peak during ascending after squatting to the deepest point. Novice women may have better movement control during H-SQ. The findings may provide implications for the selection of lower limb strength training programs, assist the scientific development of training movements, and provide reference for squat movement correction, thus reducing the risk of injury for novice women in squatting practice.
... [4,6,8,9,10,11,12], 이러한 동작 들은 모두 조정경기력과 높은 상관관계가 보고되었다 [13,14]. [11,12,19]. ...
... , 이러한 동작 들은 모두 조정경기력과 높은 상관관계가 보고되었다 [13,14]. [11,12,19]. 또한, 단관절 운동은 다관절 운동에 비해 근력향상에는 큰 차이가 없는 것으 로 알려지고 있다 [20,21,22]. ...
Article
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OBJECTIVES The purpose of this study was to analyze the relationship between isokinetic leg strength and maximum Isometric Med-Thigh Pull Test(IMTP) and maximum height of Counter Movement Jump (CMJ) in Korean national rowers.METHODS Each eight male and female athletes were participated in the study. Isometric IMTP, CMJ, and isokinetic trunk, hip, and knee strength were measured to analyze the relationship between the IMTP, CMJ and isokinetic strength. The correlation between variables was analyzed by the step-wise method of multiple regression analysis after analyzing the correlation between dependent and independent variables.RESULTS Knee, Hip and trunk isokinetic flexion and extension strength showed high correlation with maximum IMTP with the all participants. Knee extension and trunk flexion isokinetic strength showed higher correlation with IMTP. Knee extension isokinetic strength showed high correlation with CMJ.CONCLUSIONS For strengthening exercise of National rowers, ipsilateral strength balance and agonistantagonist strength balance of leg and trunk should be considered to improve performance efficiently.
... The angular velocities during the fast linear condition of 3.53-3.86 rad/s still have to be characterized as noticeably lower than peak angular velocities as well as angular velocities at the corresponding knee angle during vertical jumping (6,8,32) but shows similarities to the peak angular velocities during the squat 1RM (26). When taking observations from single-joint measurements into account, where isokinetic performance of the knee extensors shows greater connections to jumping performance at high angular velocities compared to low angular velocities (22,33), the known mechanism of slight angular changes in isometric measurements and the low angular velocities in the slow linear condition observed in the present study promote the hypothesis that slow isokinetic testing might show greater similarity to isometric than to highly dynamic muscle actions. ...
Article
Problem: Since segment lengths of the lower extremities influence joint kinematics in multi-joint movements, anthropometric standardization seems necessary to study the force-length-velocity relationships of muscles in vivo. Mathematical approaches to calculate the needed linear velocities for the desired angular kinematics from individual anthropometric data exist and are in use. Nevertheless, this approach does not account for possible shifts due to cushion padding and soft tissue compression. Methods: 38 physical education students (31 male, 7 female, 24±4.32 years, 175.93±7.92 cm, 74.93±10.86 kg) participated in this investigation. Knee-angles and angle-specific force during multi-joint isokinetic leg extensions derived from an anthropometric model were compared to corresponding knee angles and forces derived from optical marker tracking for two different linear velocities (0.1 m/s and 0.7 m/s). Results: The results show significant differences (p < 0.05) in knee angles and angle-specific forces for multi-joint isokinetic leg extensions with 0.1 m/s and no significant differences for movements with 0.7 m/s. Discussion: Studies investigating force-length-velocity relationships during multi-joint leg extensions should implement optical measurement to eliminate the effects of shifts due to cushion padding and soft tissue compression especially when working with slow linear velocities. The possibility of a device-specific correction for the anthropometric model should be addressed in further research.
... Similarly, the muscular endurance exercises of the university students were focused on squat and plank. The necessity to learn the proper squat is essential especially that the movement pattern is usually used in sitting, lifting and sporting events [29] and useful to increase performance and strengthen resilience in injury [30,31,32]. In the same vein, it is relevant in performing squat that proper placement, width, and angles must be take into consideration to acquire the targeted goals [33]. ...
Article
Background And Study Aim. The rising of physical inactivity among university students amidst Covid-19 pandemic is a worldwide concern. Thus, the purpose of this research is to describe and explain the status quo of university students in terms of their physical activity engagement level. Materials and Methods. Descriptive research design was used in the study employing survey questionnaire. There were 1,648 respondents of the study from one of the Higher Educational Institutions in Cebu City, Philippines taking physical education subject. Results. Based on the survey conducted, results revealed that in spite of the presence of pandemic, university students still engage themselves in different exercise typologies and/or physical activity in varying frequency of execution to stay active. Similarly, household chores are considered as an opportunity in physical activity engagement amidst the pandemic as revealed in the study. Conclusions. Despite the challenges and online modality of learning, university students engaged in different exercise typologies to stay active in varying frequency means. Understanding university students’ physical activity’s inclination amidst the pandemic entails planning new teaching strategies and approaches which cater their interest to encourage and motivate to live an active lifestyle even staying at home with limited access to facilities. Further, the study recommended an exercise program to be used either as teaching tool for effective teaching strategies and approaches for students’ physical activity interest in online learning modality especially in this global pandemic.
... The best lifters appear to be ready to constrain the knee joint moment by exact control of the knee position concerning the ground reaction force. Miletello et al (2009) found that kinematic variable high knee angular velocity show distinction in greatest squat between competitive power lifters and amateur power lifters from the base of the lift and staying point. Coaches should concentrate on their preparation programs on expanding quality so quickening from the base of the lift increments. ...
... The best lifters appear to be ready to constrain the knee joint moment by exact control of the knee position concerning the ground reaction force. Miletello et al (2009) found that kinematic variable high knee angular velocity show distinction in greatest squat between competitive power lifters and amateur power lifters from the base of the lift and staying point. Coaches should concentrate on their preparation programs on expanding quality so quickening from the base of the lift increments. ...
Book
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About the Book: This book compiled with quality research papers of the Two Day International E-Conference on “Trends Issues and Development of Physical Education and Sports” under the theme of “All round development of human personality” jointly organised by Department of Physical Education and Sports Science, Fit India Campaign Committee and Fit India Club, Manipur University, Canchipur in collaboration with National Association of Physical Education and Sports Science (NAPESS). This book has been undertaken by the organisers to share the knowledge of the professionals through their research papers and to exchange their experience and research finding area in the field of physical educational and sports science. This is the book of the reviews on the concrete solutions to the permanent problems in the physical education and sports science. It is a humble energy to bind the drowning talents of physical education and sports. We express our gratitude, to those humble physical education teachers, research scholars, students, sports lovers, coaches, and sports administrators, who made this chance. Editor Dr. L.Santosh Singh
... Although an individual may be able to withstand a supramaximal load at the start of a squat, there is an increased likelihood of failure, concomitant with risk of injury, during the approach to a deeper squat position. Furthermore, movement velocity varies over the duration of the movement (Miletello et al. 2009), so accurately measuring eccentric force and velocity over repeated trials may prove challenging. To overcome these difficulties, advances in technology, using the Kineo Training System (v7.0, Globus, Italy) ( Fig. 1), allow for the application of multi-joint isovelocity movements, by manipulating the external force at a constant velocity over the duration of the exercise. ...
Article
Full-text available
Purpose The force–velocity relationship of muscular contraction has been extensively studied. However, previous research has focussed either on isolated muscle or single-joint movements, whereas human movement consists of multi-joint movements (e.g. squatting). Therefore, the purpose of this study was to investigate the force–velocity relationship of isovelocity squatting. Methods Fifteen male participants (24 ± 2 years, 79.8 ± 9.1 kg, 177.5 ± 6 cm) performed isovelocity squats on a novel motorised isovelocity device (Kineo Training System) at three concentric (0.25, 0.5, and 0.75 m s⁻¹) and three eccentric velocities (− 0.25, − 0.5, and − 0.75 m s⁻¹). Peak vertical ground reaction forces, that occurred during the isovelocity phase, were collected using dual force plates (2000 Hz) (Kistler, Switzerland). Results The group mean squat force–velocity profile conformed to the typical in vivo profile, with peak vertical ground reaction forces during eccentric squatting being 9.5 ± 19% greater than isometric (P = 0.037), and occurring between − 0.5 and − 0.75 m s⁻¹. However, large inter-participant variability was identified (0.84–1.62 × isometric force), with some participants being unable to produce eccentric forces greater than isometric. Sub-group analyses could not identify differences between individuals who could/could not produce eccentric forces above isometric, although those who could not tended to be taller. Conclusions These finding suggest that variability exists between participants in the ability to generate maximum eccentric forces during squatting, and the magnitude of eccentric increase above isometric cannot be predicted solely based on a concentric assessment. Therefore, an assessment of eccentric capabilities may be required prior to prescribing eccentric-specific resistance training.
... Unlike the knee angle of 120 degrees, which corresponds to the highest force output of dynamic singlejoint movement, 79,100 the knee angle of 90 degrees corresponded to the 'sticking point', where the mechanical advantage is at its lowest. 3,97 The results of the study showed a significant correlation between the 1RM back squat and the IPF at 90 degrees (r = 0.864) and 120 degrees (r = 0.597). ...
Article
Full-text available
Barbell strength sports such as weightlifting (WL) and powerlifting (PL) have been slow to adopt modern athlete monitoring practices. Obstacles such as a lack of resources, experience, and knowledge dealing with athlete monitoring stand in the way of their implementation into these sports. Therefore, the purposes of this review are: 1) to synthesise the scientific literature most relevant to the monitoring of strength athletes, and 2) to provide practical recommendations to the strength sport coach for implementing an athlete monitoring programme.
... GymAware Testing for Barbell Back Squat. As previous literature has described the rate of acceleration immediately following the bottom of the squat as a major predictor of powerlifter squat skill, measures of velocity during submaximal and maximal barbell squats may inform whether varying knee sleeve tightness can augment muscular power similar to knee wraps (7,20). GymAware (Kinetic Performance Technology, Mitchell ACT, Australia) is a commercially available linear position transducer that reliably provides kinematic information in the back squat (26). ...
Article
Neoprene knee sleeves are commonly employed by powerlifters and recreational users, but are heavily under-researched. Furthermore, no data exist on whether knee sleeves of varying compressive tightness impact muscular performance similar to commonly used knee wraps, which are both generally effective and more so when increasingly constrictive. Fifteen resistance trained, knee sleeve-naïve, recreational weight lifting males (22.1±4.1y; 177.5±5.9cm; 87.8±7.8kg) visited the laboratory on three separate occasions one week apart, assigned in a randomized, crossover, and counterbalanced fashion to either a minimally-supportive control condition knee sleeve (CS), manufacturer-recommended sizing neoprene knee sleeve (NS), or a one-size smaller (than NS) neoprene knee sleeve (TS). On each visit, subjects sequentially completed vertical jump (countermovement and squat jumps for both peak and mean power), one-repetition maximum (1RM) barbell squat and GymAware assessments (peak power, peak velocity, and dip) at 90% (reported) and 100% (tested) 1RM, as well as one-leg extension (1RM, repetitions to failure and total volume-load at 75%1RM) tests. All data was analyzed via one-way repeated measures ANOVA at p<.05. Analysis revealed a significant condition effect on barbell squat 1RM (p=.003; η2=.339) , whereby both NS (p=.044; 166±24kg) and TS (p=.019; 166±21kg) outperformed CS Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation (161±22kg), with no difference between neoprene sleeves. Conversely, no other tested parameters differed between knee sleeve conditions (p > .05). The present results demonstrate that neoprene knee sleeves may function independent of tightness, relative to recommended sizing and ultimately unlike knee wraps. Furthermore, the singular benefits observed on barbell squat maximal strength potentially suggests an exercise-specific benefit yet to be fully elucidated.
Article
In the analysis of human movement, researchers often sum individual joint kinetics to obtain a single measure of lower extremity function. The extent to which these summed measures relate to the mechanical objectives of the task has not been formally validated. The criterion validity of these measures was established with comparisons to the mechanical objective of two multiple-joint tasks. For the Work task 18 participants performed a loaded barbell squat using 4 resistances while instrumented for biomechanical analysis. For the Power they performed 2 predetermined amounts of work at both self-selected and fast speeds. Using inverse dynamics techniques, the peak net joint moment (PM) was calculated bilaterally in the sagittal plane at the ankle, knee, and hip and was summed into a single measure. This measure was correlated with the task objectives using simple linear regression. Similar procedures were used for the average net joint moment (AM), peak (PP), and average (AP) net joint moment power, and the net joint moment impulse (IM) and work (IP). For the Work task all 6 measures were significantly correlated with the task objective, but only AM, PM, and IP had correlation coefficients above 0.90. For the Power task, IM was not significantly correlated with the task objective, and only AP had a correlation coefficient above 0.90. These findings indicate that the validity of summing individual kinetic measures depends on both the measure chosen and the mechanical objective of the task.
Article
The purpose of this study was to formulate a kinematic model of performance in the parallel squat, based on the movement characteristics of world class powerlifters, and to determine if the model could be utilized to assess technique differences between high and less-skilled subjects. Two trials were recorded via high-speed cinematography from a side view of twenty-four Ss during the 1974 U.S. Senior National A.A.U. Powerlifting Championships. Vertical and horizontal displacement patterns of three joint centers and the center of the bar were determined for the best trial of each S. These data were subsequently used to calculate desired linear and angular coordinates, velocities and accelerations for body segments and bar. Results indicated that although there was some variability in most kinematic parameters, vertical bar velocity was found to be very similar among competitors, even for Ss of different bodyweight. Consequently, the vertical velocity of the bar was selected as the parameter around which performance could be modeled in the parallel squat. A model was formulated by plotting the mean values in vertical bar velocity for all Ss scaled to a common time base. The resultant model was contrasted with vertical bar velocity data for less-skilled Ss to assess typical performance errors. (C)1977The American College of Sports Medicine
Article
The purpose of this study was to formulate a kinematic model of performance in the parallel squat, based on the movement characteristics of world class powerlifters, and to determine if the model could be utilized to assess technique differences between high and less-skilled subjects. Two trials were recorded via high-speed cinematography from a side view of twenty-four Ss during the 1974 U.S. Senior National A.A.U. Powerlifting Championships. Vertical and horizontal displacement patterns of three joint centers and the center of the bar were determined for the best trial of each S. These data were subsequently used to calculate desired linear and angular coordinates, velocities and accelerations for body segments and bar. Results indicated that although there was some variability in most kinematic parameters, vertical bar velocity was found to be very similar among competitors, even for Ss of different bodyweight. Consequently, the vertical velocity of the bar was selected as the parameter around which performance could be modeled in the parallel squat. A model was formulated by plotting the mean values in vertical bar velocity for all Ss scaled to a common time base. The resultant model was contrasted with vertical bar velocity data for less-skilled Ss to assess typical performance errors.
Article
Past studies have produced conflicting results as to the effect of squat exercises on knee stability. One hundred male and female college students were measured using a knee ligament arthrometer on nine tests of knee stability. Over an 8-wk training program, full or half squats did not consistently affect knee stability compared to non-squatting controls. To measure the effect of long-term squat training 27 male powerlifters (14 Elite or Master Class) and 28 male weightlifters (8 Elite or Master Class) were measured on the same tests. Powerlifters were significantly tighter than controls on the anterior drawer at 90 degrees of knee flexion. Both powerlifters and weightlifters were significantly tighter than controls on the quadriceps active drawer at 90 degrees of knee flexion. Data on powerlifters and weightlifters were also analyzed by years of experience and skill level. No effect of squat training on knee stability was demonstrated in any of the groups tested.
Article
A questionnaire, designed to elicit information about the training, experience, and medical history of adolescent powerlifters, was administered to 71 contestants entered in the 1981 Michigan Teenage Powerlifting Championship. The average subject had participated in 4.1 workouts per week for 17.1 months. Each workout lasted an average of 99.2 minutes. The population sustained 98 powerlifting injuries which caused a discontinuance of training for a total of 1,126 days. The incidence and severity of pain in 13 regions of the body, as well as the site and type of powerlifting injury, were investigated. The low back region was shown to be the site with the greatest number of injuries (49). This region also had the highest percent of subjects recording an elevated occurrence and level of pain associated with powerlifting.
Article
Because a strong and stable knee is paramount to an athlete's or patient's success, an understanding of knee biomechanics while performing the squat is helpful to therapists, trainers, sports medicine physicians, researchers, coaches, and athletes who are interested in closed kinetic chain exercises, knee rehabilitation, and training for sport. The purpose of this review was to examine knee biomechanics during the dynamic squat exercise. Tibiofemoral shear and compressive forces, patellofemoral compressive force, knee muscle activity, and knee stability were reviewed and discussed relative to athletic performance, injury potential, and rehabilitation. Low to moderate posterior shear forces, restrained primarily by the posterior cruciate ligament (PCL), were generated throughout the squat for all knee flexion angles. Low anterior shear forces, restrained primarily by the anterior cruciate ligament (ACL), were generated between 0 and 60 degrees knee flexion. Patellofemoral compressive forces and tibiofemoral compressive and shear forces progressively increased as the knees flexed and decreased as the knees extended, reaching peak values near maximum knee flexion. Hence, training the squat in the functional range between 0 and 50 degrees knee flexion may be appropriate for many knee rehabilitation patients, because knee forces were minimum in the functional range. Quadriceps, hamstrings, and gastrocnemius activity generally increased as knee flexion increased, which supports athletes with healthy knees performing the parallel squat (thighs parallel to ground at maximum knee flexion) between 0 and 100 degrees knee flexion. Furthermore, it was demonstrated that the parallel squat was not injurious to the healthy knee. The squat was shown to be an effective exercise to employ during cruciate ligament or patellofemoral rehabilitation. For athletes with healthy knees, performing the parallel squat is recommended over the deep squat, because injury potential to the menisci and cruciate and collateral ligaments may increase with the deep squat. The squat does not compromise knee stability, and can enhance stability if performed correctly. Finally, the squat can be effective in developing hip, knee, and ankle musculature, because moderate to high quadriceps, hamstrings, and gastrocnemius activity were produced during the squat.
Article
The purpose of this study was to quantify biomechanical parameters employing two-dimensional (2-D) and three-dimensional (3-D) analyses while performing the squat with varying stance widths. Two 60-Hz cameras recorded 39 lifters during a national powerlifting championship. Stance width was normalized by shoulder width (SW), and three stance groups were defined: 1) narrow stance squat (NS), 107 +/- 10% SW; 2) medium stance squat (MS), 142 +/- 12% SW; and 3) wide stance squat (WS), 169 +/- 12% SW. Most biomechanical differences among the three stance groups and between 2-D and 3-D analyses occurred between the NS and WS. Compared with the NS at 45 degrees and 90 degrees knee flexion angle (KF), the hips flexed 6-11 degrees more and the thighs were 7-12 degrees more horizontal during the MS and WS. Compared with the NS at 90 degrees and maximum KF, the shanks were 5-9 degrees more vertical and the feet were turned out 6 degrees more during the WS. No significant differences occurred in trunk positions. Hip and thigh angles were 3-13 degrees less in 2-D compared with 3-D analyses. Ankle plantar flexor (10-51 N.m), knee extensor (359-573 N.m), and hip extensor (275-577 N.m) net muscle moments were generated for the NS, whereas ankle dorsiflexor (34-284 N.m), knee extensor (447-756 N.m), and hip extensor (382-628 N.m) net muscle moments were generated for the MS and WS. Significant differences in ankle and knee moment arms between 2-D and 3-D analyses were 7-9 cm during the NS, 12-14 cm during the MS, and 16-18 cm during the WS. Ankle plantar flexor net muscle moments were generated during the NS, ankle dorsiflexor net muscle moments were produced during the MS and WS, and knee and hip moments were greater during the WS compared with the NS. A 3-D biomechanical analysis of the squat is more accurate than a 2-D biomechanical analysis, especially during the WS.
Article
The specific aim of this project was to quantify knee forces and muscle activity while performing squat and leg press exercises with technique variations. Ten experienced male lifters performed the squat, a high foot placement leg press (LPH), and a low foot placement leg press (LPL) employing a wide stance (WS), narrow stance (NS), and two foot angle positions (feet straight and feet turned out 30 degrees ). No differences were found in muscle activity or knee forces between foot angle variations. The squat generated greater quadriceps and hamstrings activity than the LPH and LPL, the WS-LPH generated greater hamstrings activity than the NS-LPH, whereas the NS squat produced greater gastrocnemius activity than the WS squat. No ACL forces were produced for any exercise variation. Tibiofemoral (TF) compressive forces, PCL tensile forces, and patellofemoral (PF) compressive forces were generally greater in the squat than the LPH and LPL, and there were no differences in knee forces between the LPH and LPL. For all exercises, the WS generated greater PCL tensile forces than the NS, the NS produced greater TF and PF compressive forces than the WS during the LPH and LPL, whereas the WS generated greater TF and PF compressive forces than the NS during the squat. For all exercises, muscle activity and knee forces were generally greater in the knee extending phase than the knee flexing phase. The greater muscle activity and knee forces in the squat compared with the LPL and LPH implies the squat may be more effective in muscle development but should be used cautiously in those with PCL and PF disorders, especially at greater knee flexion angles. Because all forces increased with knee flexion, training within the functional 0-50 degrees range may be efficacious for those whose goal is to minimize knee forces. The lack of ACL forces implies that all exercises may be effective during ACL rehabilitation.