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The American Journal of Sports
Medicine
http://ajs.sagepub.com/
Effects of Sports Injury Prevention Training on the Biomechanical Risk Factors of Anterior Cruciate
Ligament Injury in High School Female Basketball Players
Bee-Oh Lim, Yong Seuk Lee, Jin Goo Kim, Keun Ok An, Jin Yoo and Young Hoo Kwon
Am J Sports Med 2009 37: 1728 originally published online June 26, 2009
DOI: 10.1177/0363546509334220
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Effects of Sports Injury Prevention Training
on the Biomechanical Risk Factors of
Anterior Cruciate Ligament Injury in High
School Female Basketball Players
Bee-Oh Lim,* PhD, Yong Seuk Lee,†‡ MD, Jin Goo Kim,§ MD, Keun Ok An,ll MS,
¶
#
Jin Yoo, PhD, and Young Hoo Kwon, PhD
‡
From *Sports Science Institute, Seoul National University, Seoul, Korea, Department of
§
Orthopaedic Surgery, Korea University Ansan Hospital, Ansan, Korea, Department of
ll
Orthopedic Surgery, Seoul Paik Hospital, Inje University, Seoul, Department of Physical
¶
Education, Dankook University, Seoul, Department of Physical Education, Chung Ang
#
University, Seoul, and Department of Kinesiology, Texas Woman’s University, Denton, Texas
Background: Female athletes have a higher risk of anterior cruciate ligament injury than their male counterparts who play at
similar levels in sports involving pivoting and landing.
Hypothesis: The competitive female basketball players who participated in a sports injury prevention training program would
show better muscle strength and flexibility and improved biomechanical properties associated with anterior cruciate ligament
injury than during the pretraining period and than posttraining parameters in a control group.
Study Design: Controlled laboratory study.
Methods: A total of 22 high school female basketball players were recruited and randomly divided into 2 groups (the experimental
group and the control group, 11 participants each). The experimental group was instructed in the 6 parts of the sports injury
prevention training program and performed it during the first 20 minutes of team practice for the next 8 weeks, while the control
group performed their regular training program. Both groups were tested with a rebound-jump task before and after the 8-week
period. A total of 21 reflective markers were placed in preassigned positions. In this controlled laboratory study, a 2-way analysis
of variance (2 × 2) experimental design was used for the statistical analysis (P < .05) using the experimental group and a testing
session as within and between factors, respectively. Post hoc tests with Sidak correction were used when significant factor
effects and/or interactions were observed.
Results: A comparison of the experimental group’s pretraining and posttraining results identified training effects on all strength
parameters (P = .004 to .043) and on knee flexion, which reflects increased flexibility (P = .022). The experimental group showed
higher knee flexion angles (P = .024), greater interknee distances (P = .004), lower hamstring-quadriceps ratios (P = .023), and
lower maximum knee extension torques (P = .043) after training. In the control group, no statistical differences were observed
between pretraining and posttraining findings (P = .084 to .873). At pretraining, no significant differences were observed between
the 2 groups for any parameter (P = .067 to .784). However, a comparison of the 2 groups after training revealed that the
experimental group had significantly higher knee flexion angles (P = .023), greater knee distances (P = .005), lower hamstringquadriceps ratios (P = .021), lower maximum knee extension torques (P = .124), and higher maximum knee abduction torques
(P = .043) than the control group.
Conclusion: The sports injury prevention training program improved the strength and flexibility of the competitive female
basketball players tested and biomechanical properties associated with anterior cruciate ligament injury as compared with
pretraining parameters and with posttraining parameters in the control group.
Clinical Relevance: This injury prevention program could potentially modify the flexibility, strength, and biomechanical properties
associated with ACL injury and lower the athlete’s risk for injury.
Keywords: anterior cruciate ligament (ACL); female; biomechanical deficit; injury prevention program
†
Address correspondence to Yong Seuk Lee, MD, Department of Orthopaedic Surgery, Korea University Ansan Hospital, 516 Gozan-1-dong, Danwon-gu,
Ansan 425-707, Korea (e-mail: smcos1@hanmail.net).
No potential conflict of interest declared.
The American Journal of Sports Medicine, Vol. 37, No. 9
DOI: 10.1177/0363546509334220
© 2009 The Author(s)
1728
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Injury Prevention Training and Risk of ACL Injury 1729
Vol. 37, No. 9, 2009
Female athletes have a 4- to 6-fold higher risk of anterior
cruciate (ACL) injury than their male counterparts who
play the same sports at similar levels.1,10,19 An increased
ACL injury risk coupled with an increase in sports
participation by young women has fueled many genderspecific mechanistic and interventional investigations.10
The mechanism underlying gender disparity of ACL injury
risk is likely multifactorial in nature, and several theories
have been proposed to explain the phenomenon.12 These
theories include related extrinsic variables (physical and
visual perturbations, bracing, and shoe-surface interactions)
and intrinsic variables (anatomic, hormonal, neuromus­
cular, and biomechanical differences between genders).10
The biomechanical risk factors that appear to play a major
role in noncontact ACL injuries are greater knee extension
and valgus moments during the landing phase of a jumpand-stop task,4,17 less knee flexion and more hip and knee
internal rotation than male athletes during single-legged
landings,14 and greater dependence on the quadriceps to
stabilize the knee as compared with male athletes.15 With
regard to environmental, anatomic, and hormonal risk
factors, there is no conclusive evidence that these factors
are directly correlated with an elevated risk of ACL injury
in female athletes. Furthermore, most of these factors are
congenital factors and are not easily controlled.6 Therefore,
emphasis has turned to physical and biomechanical risk
factors and the use of neuromuscular and proprioceptive
intervention programs to address potential deficits.4,14-17
Most prevention programs target modifying dynamic
loading through neuromuscular training. Mandelbaum
et al16 reported that neuromuscular training programs
reduce ACL injuries in female athletes, and the primary
goal of their training program was to address feed-forward
mechanisms to allow external forces to be better anticipated
or to load and stabilize the joint.16 However, in this
previous report, only the incidences of ACL injuries after a
training program were reported. Our injury prevention
program is a modification of the one used by Mandelbaum
et al, and we undertook to evaluate its effect on muscle
strength, flexibility, and biomechanical properties.
The hypothesis of this study was that competitive female
basketball players who participated in our sports injury
prevention training program (SIPTP) would show increased
muscle strength, flexibility, and improved biomechanical
properties as compared with their pretraining values and
with posttraining values in a control group.
The purpose of this study was to determine whether our
injury prevention program is effective at increasing the
muscle strength and flexibility of competitive female
basketball players and improving biomechanical properties
related to ACL injury. This was evaluated by measuring
differences between parameters in an experimental group’s
pre-and posttraining and between the experimental group’s
and the control group’s posttraining results.
MATERIALS AND METHODS
Participants
A total of 22 high school female basketball players between
15 and 17 years of age were recruited from 2 teams in the
same area; participants had no known history of lower
extremity injuries. Participants were randomly divided
into 2 groups. From the 22 athletes, we chose 7 (height,
171.3 ± 6.9 cm; body mass, 63.9 ± 5.3 kg; age, 17.1 ± 1.1
years) randomly for a reliability test. Four participants
were from the experimental group and 3 were from the
control group.
The mean age of the experimental group was 16.2 ± 1.2
years, mean height 172.2 ± 5.3 cm, and mean body mass
64.2 ± 6.1 kg; corresponding values in the control group
were 16.1 ± 1.0 years, 170.9 ± 7.6 cm, and 64.0 ± 7.3 kg.
There were no significant differences between the 2 groups
with regard to their mean age, height, and weight. Our
institutional internal review board approved the use of
human subjects for this study. Written consent was
obtained from each of the study participants and from
their parents or guardians.
Data Collection
In the rebound jump task, the participant was instructed to
vertical jump maximally to catch the ball under the ceiling
and land on the force plate. A successful trial was defined as
a trial in which the participant performed the rebound task
as instructed and videographic and analog data were
successfully collected. Pretraining data were collected before
training sessions in both groups, and posttraining data
immediately after the completion of the 8-week training
period. Three-dimensional motion analyses of the landing
phase of the rebound jump were conducted to measure
selected kinematic and kinetic variables, which included
jump height, maximum knee flexion angle, minimum
interknee distance, maximum knee internal rotation angle,
maximum knee extension moment, and maximum knee
valgus moment. Six video cameras (Panasonic AG-D5100,
Panasonic Corp, Osaka, Japan) and 2 force plates (AMTI
ORG-6, AMTI, Watertown, Massachusetts) were used during
the motion analysis. Each camera was calibrated with a
calibration frame (2 m long × 1.5 m wide × 2 m high) before
data collection. In addition, 2 pairs of electrodes (1 cm in
diameter, 3 cm center-to-center distance) were placed on the
quadriceps (rectus femoris) and hamstring (biceps femoris)
muscles, respectively, to monitor the activities of these muscles.
Both the force plate and electromyographic (EMG) data
were collected at 1200 Hz, whereas video data were captured
at 60 fields/s. Kwon3D Version 3.1 (Visol, Seoul, Korea),
KwonGRF Version 2.0 (Visol), and MyoResearch Version
1.04 (Noraxon, Scottsdale, Arizona) were used for collecting
motion, ground-reaction, and EMG data, respectively.
During the data collection sessions, the participants
were asked to wear sports bras, spandex pants, and
comfortable basketball shoes. Spherical reflective markers
were placed at selected locations on the lower extremities
and the pelvis: toes (second), heels, lateral malleoli, medial
malleoli, lateral shanks, lateral epicondyles, medial
epicondyles, lateral thighs, greater trochanters, anterior
superior iliac spines (ASIS), and sacrum (Figure 1). The
lateral shank and thigh markers were placed on the lateral
aspects of the midshank and thigh, respectively, on the line
connecting the proximal and distal joints of the respective
segments projected to the sagittal plane. A static trial
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1730 Lim et al
The American Journal of Sports Medicine
Figure 1. Static marker set: 21 reflective markers were placed
at the right and left toe, right and left heel, right and left lateral
malleolus, right and left medial malleolus, right and left
midshank, right and left lateral epicondyle, right and left medial
epicondyle, right and left mid thigh, right and left greater
trochanter, right and left anterior superior iliac spines (ASIS), and
the sacrum for the 3-dimentional kinematic data.
(upright standing position with arms folded on the chest
and feet 20 cm apart) was performed on each participant
during each testing session to establish the relative
positions of joint centers (hip, knee, and ankle) with
respect to surface markers and the relative orientations of
segmental reference frames to the global (laboratory)
reference frame. Medial epicondyle and malleolus markers
and greater trochanter markers were subsequently
removed in the dynamic (rebound jump) trials. To compute
resultant joint moments in each leg, the rebound jump
task was performed on 2 separate force plates embedded in
the floor, and this was followed by a 2-footed landing on the
respective plates (Figure 2).
Training Protocol
The SIPTP for this study consists of 6 parts (Table 1) and
was a modification of Mandelbaum’s Prevent Injury and
Enhance Performance (PEP) Program.16 The correct
training technique was demonstrated to coaches and
players during a 1.5-hour training session, which was
Figure 2. To compute the resultant joint moments of joints in
each leg, the rebound jump task was performed on 2 separate
force plates that were embedded in the floor, and then followed
by a 2-footed landing on the respective plates.
conducted on practice fields. To encourage compliance and
to ensure that exercises were performed correctly, trained
personnel (athletic trainers) were present at all training
sessions and corrected the techniques of the experimental
group participants as needed. During the 8 weeks, the
athletic trainer performed 3 follow-up checks (at 2, 4, and
6 weeks) to ensure that exercises were being performed
correctly, and helped to encourage compliance by repeating
the 1.5-hour training session. The experimental group
performed the SIPTP during the first 20 minutes of their
regular team basketball practice for the next 8 weeks,
while the control group performed their regular training
program for the next 8 weeks.
Data Processing
Three-dimensional (3-D) marker coordinates were computed
from the 2-D image coordinates of markers and camera
parameters. Marker coordinates were subject to digital
filtering using a fourth-order zero phase-lag Butterworth
low-pass filter with a cutoff frequency of 12 Hz before
computing positional data. The position of hip joint center
was computed based on those of the ASIS (right and left),
sacrum, and greater trochanter markers as detailed in the
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Injury Prevention Training and Risk of ACL Injury 1731
Vol. 37, No. 9, 2009
TABLE 1
Sports Injury Prevention Training Program (SIPTP)
Distance
Exercise
1. Warm-up
Jog line to line
Shuttle run (side to side)
Backward running
2. Stretching
Calf stretch
Quadriceps stretch
Hamstring stretch
Inner thigh stretch
Hip flexor stretch
3. Strengthening
Walking lunges
Russian hamstring
Single toe raises
4. Plyometrics
Lateral hops over cone
Forward/backward hops over cone
Single-leg hops over cone
Vertical jumps with headers
Scissors jump
5. Agilities
Shuttle run with forward/backward running
Diagonal runs
Bounding runs
6. Alternative exercise–warm down
Bridging with alternating hip flexion
Abdominal crunches
Single and double knee to chest (supine)
Piriformis stretch–supine
Seated butterfly stretch–seated
Tylkowsky-Andriacchi hybrid method.2 Knee and ankle
joint centers were defined as the midpoints of the medial
and lateral epicondyles and malleoli, respectively. Thigh
and shank reference frames were defined from the
positions of joint centers (hip, knee, and ankle) and lateral
markers (lateral thigh and lateral shank). Vectors drawn
from distal to proximal joint were used as longitudinal
axes, and the plane formed by proximal and distal
joints and the corresponding lateral marker was used as
the frontal plane. The knee flexion/extension angle and
knee internal/external rotation angle were obtained
from the relative orientation of the shank reference frame
versus thigh reference frame. To do this, the relative
orientation angles (Euler angles) of the shank to the thigh
were computed based on the rotation sequence of flexion/
extension→adduction/abduction→internal/external
rotation. Three-dimensional motion data and groundreaction force data were combined to compute knee flexion/
extension and adduction/abduction moment using the
inverse dynamics procedures. These raw EMG data were fullwave rectified and low-pass filtered (Butterworth low-pass
filter; cutoff frequency = 10 Hz) to produce a linear envelope.
Signals were then integrated. Hamstring-quadriceps (H-Q)
100 yd
100 yd
100 yd
Repetitions/Cumulative Time
0-1 min
1-2 min
2-3 min
30
30
30
20
30
sec
sec
sec
sec
sec
×
×
×
×
×
2
2
2
3
2
reps
reps
reps
reps
reps
(3-4
(4-5
(5-6
(6-7
(7-8
min)
min)
min)
min)
min)
3 sets × 10 reps (8-9 min)
3 sets × 10 reps (9-10 min)
2 sets × 30 reps (10-11 min)
20
20
20
20
20
50 yd
50 yd (3 passes)
50 yd
reps
reps
reps
reps
reps
(11-11.5
(11.5-12
(12-12.5
(12.5-13
(13-13.5
min)
min)
min)
min)
min)
13.5-14 min
14-14.5 min
14.5-15 min
30
30
30
30
30
reps (15-16 min)
sec × 2 reps (16-17
sec × 2 reps (17-18
sec × 2 reps (18-19
sec × 2 reps (19-20
min)
min)
min)
min)
ratio (%) was defined as: rectus femoris IEMG [integrated
EMG] average/(biceps femoris IEMG average + rectus
femoris IEMG average) × 100.
Hip flexion, knee flexion, and ankle dorsiflexion were
measured to determine range of motion and measure
flexibility using a goniometer. This was done by actually
measuring the athletes separately from the motion analysis
session. Isokinetic strength data were recorded using a
Biodex System III dynamometer (Biodex Medical Inc,
Shirley, New York) to assess peak torque and average
power. The participants performed 5 isokinetic concentric
hip abduction, hip extension, and knee flexion repetitions
of the dominant limb at 60 deg/s.14 Interknee distance was
calculated by measuring distance between right and left
knee joint centers in the coronal plane.
Statistics
The following dependent variables were computed in this
study: jump height, maximum knee flexion angle, minimum
interknee distance, maximum knee internal rotation angle,
maximum knee extension moment, maximum knee valgus
moment, and H-Q ratio. This study was a controlled
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1732 Lim et al
The American Journal of Sports Medicine
TABLE 2
Changes in Strength and Flexibilitya
Pretest
Experiment
Variable
Muscle strength
Peak torque (N.m/BW)
Average power (W/BW)
Peak torque (N.m/BW)
Average power (W/BW)
Peak torque (N.m/BW)
Average power (W/BW)
Hip abduction
Hip extension
Knee flexion
Flexibility
Hip flexion (deg)
Knee flexion (deg)
Ankle dorsiflexion (deg)
2.80
0.96
5.51
2.11
2.13
1.74
80.25
121.92
75.08
(0.40)
(0.15)
(0.56)
(0.20)
(0.33)
(0.28)
(12.14)
(7.12)
(11.08)
Posttest
Control
2.98
1.05
5.57
2.24
2.21
1.77
78.91
124.09
74.82
Experiment
(0.84)
(0.30)
(1.90)
(0.86)
(0.31)
(0.27)
(8.38)
(5.03)
(10.98)
b
3.17
b
1.15
b
7.08
2.82b
2.36b
1.90b
83.36
127.45b
78.82
(0.22)
(0.12)
(1.11)
(0.27)
(0.20)
(0.11)
(5.95)
(4.89)
(5.95)
Control
2.88c (0.45)
1.06c (0.17)
5.60c (0.75)
2.16c (0.55)
2.10c (0.10)
1.76c (0.16)
c
73.13 (7.30)
123.13c (3.36)
73.88c (4.32)
a
Data shown are means, with standard deviation in parentheses. BW, body weight.
Statistically significant difference between pre- and posttraining data in the experimental group.
c
Statistically significant difference between experimental and control group in the posttraining data.
b
TABLE 3
Changes in Risk Factorsa
Pretest
Variable
Experiment
Jump height (cm)
Maximum knee flexion angle (deg)
Knee distance (cm)
Maximum knee internal rotation angle (deg)
H-Q ratios (%)b
Maximum knee extension torque (N.m)
Maximum knee valgus moment (N.m)
22.9
92.66
17.56
4.01
75.09
236.96
11.30
(3.4)
(4.34)
(2.92)
(1.56)
(5.69)
(39.03)
(14.11)
Posttest
Control
22.4
91.71
18.31
4.55
74.60
220.51
9.35
(4.4)
(4.25)
(3.66)
(4.20)
(5.74)
(54.14)
(7.09)
Experiment
23.9
94.27b
20.81b
2.26
67.97b
192.18b
3.89
(1.8)
(3.44)
(1.37)
(3.60)
(4.18)
(12.37)
(5.76)
Control
22.7
87.31c
17.73c
4.27
74.20c
228.80c
16.29c
(4.8)
(5.34)
(2.26)
(3.36)
(5.21)
(45.65)
(14.15)
a
Data shown are means, with standard deviation in parentheses. H-Q, hamstring-quadriceps.
Statistically significant difference between pre- and posttraining data in the experimental group.
c
Statistically significant difference between experimental and control group in the posttraining data.
b
laboratory study and 2-way analyses of variance (2 × 2)
were used with the experimental group and testing session
as the between and within factors, respectively. Post hoc
tests with the Sidak correction were performed when
significant factor effects and/or interactions were observed.
P values of < .05 were considered statistically significant.
RESULTS
A power analysis for 2-way analysis of variance (2 groups ×
testing session) was performed for an effect size of 0.5 based
on pilot hip abduction peak torque (0.3-N·m/body weight
[BW] difference), hip abduction average power (0.05 W/BW
difference), hip extension peak torque (1.4-N·m/BW difference), hip extension average power (0.6-W/BW difference),
knee flexion peak torque (0.2-N·m/BW difference), knee
flexion average power (0.2-W/BW difference), hip flexion
flexibility (10.0° difference), knee flexion flexibility (4.0° difference), ankle dorsiflexion flexibility (5.0° difference),
maximum knee flexion angle (1.6° difference), knee distance
(2.1-cm difference), H-Q ratios (11.0% difference), maximum
knee extension torque (28.0-N.m difference), and maximum
knee valgus moment (12.0-N.m difference) using the PASS
2002 program for power analysis by NCSS (Kaysville,
Utah). We found that a minimum of 10 participants per
group were needed for a power of 94% for P = .05.
Initially 24 athletes were included in this study; however,
only 22 finished the entire study (a retention rate of 91.7%).
Of the 2 athletes who dropped out of this study after the
pretest, 1 control group member stopped playing basketball
for unknown personal reasons, and the other experimental
group participant joined the Junior National Team.
Therefore, each group in the end contained 11 female participants. Seven players participated in the reliability
assessment of the testing procedure.5 The sessions were
held no more than 2 days apart at approximately the same
time of day. The reliabilities of knee flexion angle (intraclass
correlation coefficient [ICC]= 0.923), knee distance (ICC =
0.910), and knee internal rotation angle (ICC = 0.879) were
high for all athletes tested. All trials were successful and
results are summarized in Tables 2 and 3.
A comparison of the experimental group’s pre- and
posttraining results identified training effects on all
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Injury Prevention Training and Risk of ACL Injury 1733
Vol. 37, No. 9, 2009
There were no statistical differences between the 2
groups with regard to any pretraining parameters (P =
.067 to .784). However, when the 2 groups were compared
after training, the experimental group had greater knee
flexion angle (P = .023), knee distance (P = .005), and
maximum knee abduction torque (P = .043); a smaller H-Q
ratio (P = .021); and less maximum knee extension torque
(P = .124). However, there was no difference in jump height
or in maximum knee internal rotation angle after the
training program completion (P = .512, .432).
Knee Flexion Angle (A)
100
(degrees)
80
60
40
20
0
DISCUSSION
Knee Extensor Moment (B)
4
(N-m/kg)
3
2
1
0
--1
Knee Joint Power (C)
(Watts/kg)
40
20
0
--20
--40
0
10
20
30
40
50
60
70
80
90
100
% Stance Phase
Figure 3. Pretraining (dotted line) and posttraining (solid line)
mean knee angle (A), moment (B), and power curves (C) for
the stance phase of the rebound task. Moment and power
were normalized to body weight. Positive values of power
indicate energy generation from concentric muscle actions,
and negative values indicate energy absorption through
eccentric muscle actions.
strength parameters (P = .004 to .043) and on knee flexion,
which reflects increased flexibility (P = .022). However,
there was no difference in the hip flexion or ankle
dorsiflexion with regard to flexibility after the training
program was complete (P = .07, .12). With regard to
biomechanical risk factors, the experimental group showed
an increase in knee flexion angle (P = .024) and knee
distance (P = .004), and a decrease in H-Q ratio (P = .023)
and maximum knee extension torque (P = .043). However,
there were no differences in the jump height (P = .674),
maximum knee internal rotation angle (P = .437), or
maximum knee abduction torque (P = .256) (Figure 3).
In the control group, there were no statistical differences
between the pre- and posttraining data for any of the
parameters tested (P = .084 to .873).
The consequences of ACL injury include both temporary and
permanent disability and result in both direct and indirect
costs. Anterior cruciate ligament injury may cause absence
from work, school, or sports. Implicit to the development of
injury prevention programs is the identification of athletes
who are at an increased risk for noncontact ACL injuries.
Since 1999, many studies have been published on the risk
factors for ACL injury and injury biomechanics, and many
injury prevention programs have been developed.
Furthermore, studies have tried to identify the significant
components of effective prevention programs as well as the
effect these programs have on what is known regarding
injury risk factors and biomechanics.7
Our injury prevention program is composed of 6 parts
(warm-up, stretching, strengthening, plyometrics, agility
and alternative exercise–warm down). The present study
shows that SIPTP improves muscle strength and flexibility
and the biomechanical properties associated with ACL
injury. We believe that these effects can be attributed to
SIPTP because all the training sessions were observed and
participants were instructed by 3 well-trained coaches
throughout the SIPTP. It would appear that all successful
programs contain 1 or more of the following components:
traditional stretching and strengthening activities, aerobic
conditioning, agilities, plyometrics, and risk awareness
training.7 However, intervention programs must be feasible
and practical in terms of their applicability to younger
populations because compliance is vital. Furthermore, we
believe that young athletes are more likely to be compliant
when the prevention training is a team activity and
requires little additional time on the athlete’s part. The
SIPTP has the advantage that it requires little additional
time on the athlete’s part as similar programs devised by
Mandelbaum et al16 (20 minutes) and Myklebust et al19,20
(15 minutes) because it only requires 20 minutes per
training program (from warm-up to the warm-down
exercises). Furthermore, injury prevention programs that
require substantial time are likely to suffer noncompliance
during the competitive season, such as those of Heidt et al8
(60 minutes) and Hewett et al11 (60-90 minutes).
Previous studies13,18 have demonstrated that strength
training combined with other methods, such as plyometrics,
balance, and agility training, alter the biomechanics of
the lower extremities, but Herman et al9 showed that
strength training alone does not alter knee and hip
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1734 Lim et al
The American Journal of Sports Medicine
kinematics and kinetics in female recreational athletes.
Neuromuscular training in female athletes has been shown
to increase active knee stabilization in the laboratory and to
decrease the incidence of ACL injuries among female
athletes.11-13,19,20 This training allows female athletes to
adapt and protect their ACLs from the high-impulse loading
during their performance.12,18 Chappell and Limpisvasti3
reported that the implementation of a neuromuscular
training program can alter motor control strategies in select
jumping tasks and improve athletic performance measures.
These results complement previous epidemiologic studies
and suggest that neuromuscular training programs can
potentially lower the risk of injury.
However, comparatively little investigation has been
done to determine the ideal duration of a prevention
program. Furthermore, because injuries can occur at the
beginning of a training session, it seems reasonable that
these programs should be instituted before intense-contact
practice sessions start. Some have suggested that athletes
need a minimum of 6 weeks of training. Six weeks does
correlate with the time frame needed to increase motor
recruitment, but it does not correlate with what is needed
for muscle hypertrophy or improved endurance.7 However,
the programs are effective because they train nerve-muscle
factors and perhaps 6 weeks is adequate.7
The present study has several limitations that should be
considered. First, because the groups were small, we are
uncertain that the results are generalizable to all female
basketball players. Second, the evaluation was limited to
biomechanical factors. Third, a cause (reduction of
biomechanical deficits)–result (decrease of injury incidence)
relationship cannot be assumed because the changes in
these parameters that correlate with the change in injury
rates cannot be demonstrated. Fourth, athlete satisfaction
and functional improvements were not addressed during
the present study. Finally, all measurements were
performed by individuals who participated in the study.
CONCLUSION
Our SIPTP was found to improve the strengths and
flexibilities of competitive female basketball players and to
improve biomechanical properties associated with ACL
injury as compared with pretraining status and as compared
with posttraining parameters in a control group.
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Erratum
Lim BO, Lee YS, Kim JG, An KO, Yoo J, Know YH. Effects of sports injury prevention training on the biomechanical risk
factors of anterior cruciate ligament injury in high school female basketball players. Am J Sports Med. 2009;37(9):17281734. (Original DOI: 10.1177/0363546509334220)
In the above article, the following sentence on page 1733 should be corrected:
However, when the 2 groups were compared after training, the experimental group had greater knee flexion angle
(P = .023), knee distance (P = .005), and maximum knee abduction torque (P = .043); a smaller H-Q ratio (P = .021); and
less maximum knee extension torque (P = .124).
The corrected sentence is as follows:
However, when the 2 groups were compared after training, the experimental group had greater knee flexion angle
(P = .023) and knee distance (P = .005); a smaller H-Q ratio (P = .021); and less maximum knee extension torque (P = .124)
and maximum knee abduction torque (P = .043).
The American Journal of Sports Medicine, Vol. 39, No. 3
DOI: 10.1177/0363546511400841
© 2011 The Author(s)
NP1
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