Core stability training: Does it improve sports performance

Department of Public and Occupational Health
EMGO+ Institute for Health and Care Research
VU University Medical Center, Amsterdam, the Netherlands
Evert Verhagen
CORE STABILITY
MYTH OR REALITY?
vrijdag 23 augustus 13

Evert Verhagen

EMGO+ INSTITUTE
FOR HEALTH AND CARE RESEARCH
• Interfaculty research institute of the VU University
Amsterdam and VU University Medical Center Amsterdam
• Activities deal with research in primary care and public
health, focusing on chronic diseases and aging
• Public Health is binding factor of studies ...
"the science and art of preventing disease, prolonging life and
promoting health through the organized efforts and informed choices
of society, organizations, public and private, communities and
individuals."

TWO DIMENSIONS
PopulationLaboratory
Effectiveness
Efficacy
Optimal effect for
society or individual

TWO DIMENSIONS
PopulationLaboratory
90% efficacious
10% effective
50% efficacious
50% effective
10% efficacious
90% effective

CORE STABILITY
FOR THE PUBLIC
• Core stability relates to the
bodily region bounded by the
abdominal wall, the pelvis, the
lower back and the diaphragm
and its ability to stabilise the
body during movement
Source: wikipedia

PARALLELS WITH
STRETCHING
• Stretching has become
embedded in sport folklore as
the universal strategy for injury
prevention
Thacker et al. MSSE 2004

PARALLELS WITH
STRETCHING
• Ongoing debate on the
beneficial and detrimental effects
of stretching on ...
performance
injury risk
therapeutic outcomes

1. Identify
burden of
disease
2. Define
theories
for causation
3. Establish
efficacy
4. Establish
effectiveness
5. Community
effectiveness,
economic
implications
6. Implemen-
tation
7. Program
evaluation
Tugwell et al. J Chronic Dis 1985

1
biomechanical, physical and
neurophysiological changes
2
epidemiological
(cost)effectiveness evidence
leading to clinical / practical
guidelines
3
practical & public health
impact through high
compliance and proper use of
effective measures

1
• Theoretical concept
What is CS?
• Conceptual definition
How do we define CS?
• Operational definition
Which muscles and
movements adjoin to CS?
• Measurements
Valid?
Reliable?
Responsive?
• Most of these ...
Ill described
No consensus
Contradicting results
2
epidemiological
guidelines
3
impact through high
effective measures

1
2
epidemiological
guidelines
3
impact through high
effective measures
• Theoretical concept
What is CS?
• Conceptual definition
How do we define CS?
• Operational definition
Which muscles and
movements adjoin to CS?
• Measurements
Valid?
Reliable?
Responsive?
• Most of these ...
Ill described
No consensus
Contradicting results

• Bottom up approach
• Learn from practical
and clinical
outcomes
What works in practice?
Can we measure that?
What if we repeat practical
approaches in controlled
settings?
1
2
epidemiological
guidelines
3
impact through high
effective measures

Optimizing Performance by Improving
Core Stability and Core Strength
Angela E. Hibbs,1,3
Kevin G. Thompson,1,4
Duncan French,1
Allan Wrigley2
and Iain Spears3
1 English Institute of Sport, Gateshead, UK
2 Canadian Sport Centre Pacific, Vancouver, British Columbia, Canada
3 University of Teesside, Middlesbrough, UK
4 School of Psychology and Sports Science, Northumbria University, Newcastle, UK
Contents
Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 995
1. Definition of Performance, Core Stability and Core Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 996
2. Functional Anatomy of the ‘Core’ as it Relates to Athletic Performance . . . . . . . . . . . . . . . . . . . . . . . 997
3. Types of Core Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 998
4. Evidence of Core Training Benefits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000
4.1 Rehabilitation Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1001
4.2 Athletic Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1002
5. Measuring the Core and its Relation to Performance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1004
6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1006
Abstract Core stability and core strength have been subject to research since the
early 1980s. Research has highlighted benefits of training these processes for
people with back pain and for carrying out everyday activities. However, less
research has been performed on the benefits of core training for elite athletes
and how this training should be carried out to optimize sporting perfor-
mance. Many elite athletes undertake core stability and core strength training
as part of their training programme, despite contradictory findings and
conclusions as to their efficacy. This is mainly due to the lack of a gold
standard method for measuring core stability and strength when performing
everyday tasks and sporting movements. A further confounding factor is that
because of the differing demands on the core musculature during everyday
activities (low load, slow movements) and sporting activities (high load,
resisted, dynamic movements), research performed in the rehabilitation sec-
tor cannot be applied to the sporting environment and, subsequently, data
regarding core training programmes and their effectiveness on sporting
performance are lacking.
There are many articles in the literature that promote core training pro-
grammes and exercises for performance enhancement without providing a
strong scientific rationale of their effectiveness, especially in the sporting
sector. In the rehabilitation sector, improvements in lower back injuries
have been reported by improving core stability. Few studies have observed
any performance enhancement in sporting activities despite observing
REVIEW ARTICLE
Sports Med 2008; 38 (12): 995-1008
0112-1642/08/0012-0995/$48.00/0
ª 2008 Adis Data Information BV. All rights reserved.
CS TO IMPROVE SPORTS
PERFORMANCE
• There are many articles in the
literature that promote core
training for performance
enhancement without providing a
strong scientific rationale of their
effectiveness
• Evidence of core training
benefits?
Hibbs et al. 2012

CORE TRAINING AND POTENTIAL
PERFORMANCE BENEFITS
definitions valid and reliable measures
Clinical core stability tests are not reliable
ICCs did not exceed 0.40
Weir et al. CJSM 2010
Hibbs et al. 2012

WHAT DOES THE
LITERATURE SAY?
• Improvements in core stability
and core strength following a
core training program
• Ambiguous results on
performance enhancement in
sporting activities
Indirect impact on sporting
performance by allowing athletes to
train injury free more often?
Hibbs et al. 2012

RELATIONSHIP BETWEEN CORE STABILITY,
FUNCTIONAL MOVEMENT, AND PERFORMANCE
TOMOKO OKADA, KELLIE C. HUXEL, AND THOMAS W. NESSER
Exercise Physiology Laboratory, Athletic Training Department, Indiana State University, Terre Haute, Indiana
ABSTRACT
Okada, T, Huxel, KC, and Nesser, TW. Relationship between
core stability, functional movement, and performance.
J Strength Cond Res 25(1): 252–261, 2011—The purpose
of this study was to determine the relationship between core
stability, functional movement, and performance. Twenty-eight
healthy individuals (age = 24.4 6 3.9 yr, height = 168.8 6 12.5
cm, mass = 70.2 6 14.9 kg) performed several tests in 3
categories: core stability (flexion [FLEX], extension [EXT], right
and left lateral [LATr/LATl]), functional movement screen (FMS)
(deep squat [DS], trunk-stability push-up [PU], right and left
hurdle step [HSr/HSl], in-line lunge [ILLr/ILLl], shoulder mobility
[SMr/SMl], active straight leg raise [ASLRr/ASLRl], and rotary
stability [RSr/RSl]), and performance tests (backward medicine
ball throw [BOMB], T-run [TR], and single leg squat [SLS]).
Statistical significance was set at p # 0.05. There were
significant correlations between SLS and FLEX (r = 0.500),
LATr (r = 0.495), and LATl (r = 0.498). The TR correlated
significantly with both LATr (r = 0.383) and LATl (r = 0.448).
Of the FMS, BOMB was significantly correlated with HSr (r =
0.415), SMr (r = 0.388), PU (r = 0.407), and RSr (r = 0.391).
The TR was significantly related with HSr (r = 0.518), ILLl
(r = 0.462) and SMr (r = 0.392). The SLS only correlated
significantly with SMr (r = 0.446). There were no significant
correlations between core stability and FMS. Moderate to weak
correlations identified suggest core stability and FMS are not
strong predictors of performance. In addition, existent assess-
ments do not satisfactorily confirm the importance of core stability
on functional movement. Despite the emphasis fitness profes-
sionals have placed on functional movement and core training for
increased performance, our results suggest otherwise. Although
training for core and functional movement are important to include
in a fitness program, especially for injury prevention, they should
not be the primary emphasis of any training program.
KEY WORDS power, agility, muscle endurance
INTRODUCTION
C
ore stability is achieved through stabilization of
one’s torso, thus allowing optimal production,
transfer, and control of force and motion to the
terminal segment during an integrated kinetic
chain activity (8,14,15,23). Research has demonstrated
the importance and contributions of core stability in
human movement (12) in producing efficient trunk and
limb actions for the generation, transfer, and control of
forces or energy during integrated kinetic chain activities
(3,6,8,14,18). For example, Hodges and Richardson (12)
examined the sequence of muscle activation during whole-
body movements and found that some of the core stabilizers
(i.e., transversus abdominis, multifidus, rectus abdominis,
and oblique abdominals) were consistently activated before
any limb movements. These findings support the theory
that movement control and stability are developed in
a core-to-extremity (proximal-distal) and a cephalo-caudal
progression (head-to-toe) (8).
Functional movement is the ability to produce and
maintain a balance between mobility and stability along
the kinetic chain while performing fundamental patterns
with accuracy and efficiency (20). Muscular strength,
flexibility, endurance, coordination, balance, and move-
ment efficiency are components necessary to achieve
functional movement, which is integral to performance
and sport-related skills (8,20). Direct and quantitative
measures of functional movement are limited; however,
Cook (9) proposes qualitative assessment to gain insight
about whether abnormal movements are present, which
purportedly translate to one’s level of core stability and
how it impacts performance or injury. To determine
whether relationships truly exist between core stability
and performance, functional movement and individual
components of performance, including power, strength,
and balance, must be assessed. However, relationships
between these variables have not been established. One
explanation for the lack of evidence may be a result of the
fact that universal definitions and testing methods do not
exist (1,2,20,25,26,28). We hypothesized that there would
be a significant relationship between core stability and
functional movement and between functional movement
and performance. Also, a positive relationship would
exist between core stability and functional movement.
Address correspondence to Tomoko Okada, tokada01@gmail.com.
25(1)/252–261
Journal of Strength and Conditioning Research
Ó 2011 National Strength and Conditioning Association
252 Journal of Strength and Conditioning Research
the TM
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
CS, PERFORMANCE &
FUNCTIONAL MOVEMENT?
• To examine in healthy individuals
the relationship amongst ...
Core stability
Performance
Functional Movement
• 22 healthy subjects (male &
female)
• Amateur athletes from various
sports
Okada et al. JSCR 2011

RELATIONSHIP BETWEEN CORE STABILITY,
FUNCTIONAL MOVEMENT, AND PERFORMANCE
TOMOKO OKADA, KELLIE C. HUXEL, AND THOMAS W. NESSER
Exercise Physiology Laboratory, Athletic Training Department, Indiana State University, Terre Haute, Indiana
ABSTRACT
Okada, T, Huxel, KC, and Nesser, TW. Relationship between
core stability, functional movement, and performance.
J Strength Cond Res 25(1): 252–261, 2011—The purpose
of this study was to determine the relationship between core
stability, functional movement, and performance. Twenty-eight
healthy individuals (age = 24.4 6 3.9 yr, height = 168.8 6 12.5
cm, mass = 70.2 6 14.9 kg) performed several tests in 3
categories: core stability (flexion [FLEX], extension [EXT], right
and left lateral [LATr/LATl]), functional movement screen (FMS)
(deep squat [DS], trunk-stability push-up [PU], right and left
hurdle step [HSr/HSl], in-line lunge [ILLr/ILLl], shoulder mobility
[SMr/SMl], active straight leg raise [ASLRr/ASLRl], and rotary
stability [RSr/RSl]), and performance tests (backward medicine
ball throw [BOMB], T-run [TR], and single leg squat [SLS]).
Statistical significance was set at p # 0.05. There were
significant correlations between SLS and FLEX (r = 0.500),
LATr (r = 0.495), and LATl (r = 0.498). The TR correlated
significantly with both LATr (r = 0.383) and LATl (r = 0.448).
Of the FMS, BOMB was significantly correlated with HSr (r =
0.415), SMr (r = 0.388), PU (r = 0.407), and RSr (r = 0.391).
The TR was significantly related with HSr (r = 0.518), ILLl
(r = 0.462) and SMr (r = 0.392). The SLS only correlated
significantly with SMr (r = 0.446). There were no significant
correlations between core stability and FMS. Moderate to weak
correlations identified suggest core stability and FMS are not
strong predictors of performance. In addition, existent assess-
ments do not satisfactorily confirm the importance of core stability
on functional movement. Despite the emphasis fitness profes-
sionals have placed on functional movement and core training for
increased performance, our results suggest otherwise. Although
training for core and functional movement are important to include
in a fitness program, especially for injury prevention, they should
not be the primary emphasis of any training program.
KEY WORDS power, agility, muscle endurance
INTRODUCTION
C
ore stability is achieved through stabilization of
one’s torso, thus allowing optimal production,
transfer, and control of force and motion to the
terminal segment during an integrated kinetic
chain activity (8,14,15,23). Research has demonstrated
the importance and contributions of core stability in
human movement (12) in producing efficient trunk and
limb actions for the generation, transfer, and control of
forces or energy during integrated kinetic chain activities
(3,6,8,14,18). For example, Hodges and Richardson (12)
examined the sequence of muscle activation during whole-
body movements and found that some of the core stabilizers
(i.e., transversus abdominis, multifidus, rectus abdominis,
and oblique abdominals) were consistently activated before
any limb movements. These findings support the theory
that movement control and stability are developed in
a core-to-extremity (proximal-distal) and a cephalo-caudal
progression (head-to-toe) (8).
Functional movement is the ability to produce and
maintain a balance between mobility and stability along
the kinetic chain while performing fundamental patterns
with accuracy and efficiency (20). Muscular strength,
flexibility, endurance, coordination, balance, and move-
ment efficiency are components necessary to achieve
functional movement, which is integral to performance
and sport-related skills (8,20). Direct and quantitative
measures of functional movement are limited; however,
Cook (9) proposes qualitative assessment to gain insight
about whether abnormal movements are present, which
purportedly translate to one’s level of core stability and
how it impacts performance or injury. To determine
whether relationships truly exist between core stability
and performance, functional movement and individual
components of performance, including power, strength,
and balance, must be assessed. However, relationships
between these variables have not been established. One
explanation for the lack of evidence may be a result of the
fact that universal definitions and testing methods do not
exist (1,2,20,25,26,28). We hypothesized that there would
be a significant relationship between core stability and
functional movement and between functional movement
and performance. Also, a positive relationship would
exist between core stability and functional movement.
Address correspondence to Tomoko Okada, tokada01@gmail.com.
25(1)/252–261
Journal of Strength and Conditioning Research
Ó 2011 National Strength and Conditioning Association
252 Journal of Strength and Conditioning Research
the TM
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
CS, PERFORMANCE &
FUNCTIONAL MOVEMENT?
• CS assessed through trunk
muscle endurance tests (McGill)
• Functional Movement assessed
through FMS (Cook)
• Performance ...
Backward Overhead Medicine Ball
Throw (BOMB)
T-Run Agility Test (TR)
Single-Leg Squat (SLS)

Performance Assessments
TABLE 2. Summary of correlations between core stability, functional movement screen, and performance tests (n = 28).*
BOMB TR SLS
r r2
p r r2
p r r2
p
CS
FLEX 0.092 0.01 0.643 20.292 0.09 0.131 0.500† 0.00 0.007
EXT 0.052 0.00 0.794 20.188 0.04 0.337 20.063 0.00 0.748
LATr 0.152 0.02 0.441 20.383‡ 0.15 0.045 0.495† 0.25 0.007
LATl 0.167 0.03 0.397 20.448‡ 0.20 0.017 0.498† 0.25 0.007
DS 20.229 0.05 0.241 0.108 0.01 0.585 20.225 0.05 0.249
PU 0.407‡ 0.17 0.032 20.331 0.11 0.085 0.355 0.13 0.064
HSr 0.415‡ 0.17 0.028 20.518† 0.27 0.005 0.356 0.13 0.063
HSl 0.336 0.11 0.080 20.290 0.08 0.135 0.199 0.04 0.310
ILLr 0.045 0.00 0.822 20.159 0.03 0.419 0.014 0.00 0.944
FMS
ILLl 0.361 0.13 0.059 20.462‡ 0.21 0.013 0.175 0.03 0.374
SMr 20.388‡ 0.15 0.042 0.392‡ 0.15 0.039 20.446‡ 0.20 0.017
SMl 20.055 0.00 0.781 20.099 0.01 0.616 20.246 0.06 0.207
ASLRr 0.093 0.01 0.639 20.009 0.00 0.964 0.027 0.00 0.893
ASLRl 0.083 0.01 0.674 20.038 0.00 0.848 0.073 0.01 0.710
RSr 0.391‡ 0.15 0.040 20.293 0.09 0.130 0.327 0.11 0.089
RSl 0.255 0.07 0.191 20.221 0.05 0.260 0.246 0.06 0.327
*CS = core stability; FMS = functional movement screen; BOMB = backward overhead medicine ball throw; TR = T-run; SLS =
single leg squat; FLEX = ﬂexion; EXT = extension; LATr = right lateral; LATl = left lateral; DS = deep squat; PU = core stability push-up;
HSr = right hurdle step; HSl = left hurdle step; ILLr = right in-line lunge; ILLl = left in-line lunge; SMr = right shoulder mobility; SMl = left
shoulder mobility; ASLRr = right active straight leg raise; ASLRl = left active straight leg raise; RSr = right rotary stability; RSl = left rotary
stability.
†p # 0.01.
‡p # 0.05.

CORE STABILITY AS AN
INJURY RISK FACTOR?
• Prospective study
80 females
60 males
• Core stability measures..
Hip abduction isometric strength
Hip external rotation (ER) isometric
strength
Modified Biering-Sorensen test
(posterior core)
Side bridge test (lateral core)
Core Stability Measures as Risk Factors for
Lower Extremity Injury in Athletes
DARIN T. LEETUN1
, MARY LLOYD IRELAND1
, JOHN D. WILLSON2,3
,
BRYON T. BALLANTYNE2
, and IRENE MCCLAY DAVIS2,3
1
Kentucky Sports Medicine Clinic, Lexington, KY; 2
Joyner Sportsmedicine Institute, Lexington, KY; and 3
University of
Delaware, Department of Physical Therapy, Newark, DE
ABSTRACT
LEETUN, D. T., M. L. IRELAND, J. D. WILLSON, B. T. BALLANTYNE, and I. M. DAVIS. Core Stability Measures as Risk Factors
for Lower Extremity Injury in Athletes. Med. Sci. Sports Exerc., Vol. 36, No. 6, pp. 926–934, 2004. Introduction/Purpose: Decreased
lumbo-pelvic (or core) stability has been suggested to contribute to the etiology of lower extremity injuries, particularly in females. This
prospective study compares core stability measures between genders and between athletes who reported an injury during their season
versus those who did not. Finally, we looked for one or a combination of these strength measures that could be used to identify athletes
at risk for lower extremity injury. Methods: Before their season, 80 female (mean age ϭ 19.1 Ϯ 1.37 yr, mean weight 65.1 Ϯ 10.0
kg) and 60 male (mean age ϭ 19.0 Ϯ 0.90 yr, mean weight 78.8 Ϯ 13.3 kg) intercollegiate basketball and track athletes were studied.
Hip abduction and external rotation strength, abdominal muscle function, and back extensor and quadratus lumborum endurance was
tested for each athlete. Results: Males produced greater hip abduction (males ϭ 32.6 Ϯ 7.3%BW, females ϭ 29.2 Ϯ 6.1%BW), hip
external rotation (males ϭ 21.6 Ϯ 4.3%BW, females ϭ 18.4 Ϯ 4.1%BW), and quadratus lumborum measures (males ϭ 84.3 Ϯ 32.5 s,
females ϭ 58.9 Ϯ 26.0 s). Athletes who did not sustain an injury were significantly stronger in hip abduction (males ϭ 31.6 Ϯ
7.1%BW, females ϭ 28.6 Ϯ 5.5%BW) and external rotation (males ϭ 20.6 Ϯ 4.2%BW, females ϭ 17.9 Ϯ 4.4%BW). Logistic
regression analysis revealed that hip external rotation strength was the only useful predictor of injury status (OR ϭ 0.86, 95% CI ϭ
0.77, 0.097). Conclusion: Core stability has an important role in injury prevention. Future study may reveal that differences in postural
stability partially explain the gender bias among female athletes. Key Words: GENDER, HIP STRENGTH, TRUNK ENDURANCE,
BASKETBALL, TRACK
N
umerous reports indicate that females who partici-
pate in athletics experience particular injuries at a
disproportionate rate versus males (14,26,38). Such
injuries include traumatic anterior cruciate ligament (ACL)
ruptures to overuse injuries such as patellofemoral pain
syndrome, iliotibial band friction syndrome, and femoral,
pubic, tibial, and metatarsal stress fracture (14,26,36,38).
The identification of risk factors for these lower extremity
injuries continues to interest researchers, health care profes-
sionals, and athletes alike.
Recent studies suggest that structural differences between
males and females (18,24) may lead to altered movement
patterns that may, in turn, contribute to this gender bias (12).
In a study of gender differences in runners, female subjects
demonstrated greater hip adduction, knee abduction, hip inter-
nal rotation, and tibial external rotation during the stance phase
of running (12). The authors felt that these kinematic differ-
ences placed greater demands on female lumbo-pelvic muscu-
lature, commonly referred to as the core.
Increasingly, scientists are widening their focus to include
assessment of joint mechanics proximal and distal to the
sites where injuries tend to occur. This is largely due to the
closed chain nature of athletic activities. When the distal
ends of a segment are relatively fixed, motion at one seg-
ment will influence that of all other segments in the chain.
The influence of foot mechanics on proximal structures has
been studied extensively (35,39). However, the influence of
proximal stability on lower extremity structure and pathol-
ogy remains largely unknown. Bouisset (7) initially pro-
posed that stabilization of the pelvis and trunk is necessary
for all movements of the extremities. Hodges and Richard-
son (17) later identified trunk muscle activity before the activ-
ity of the lower extremities, which he felt served to stiffen the
spine to provide a foundation for functional movements.
Considering the wide variety of movements associated
with athletics, athletes must possess sufficient strength in
hip and trunk muscles that provide stability in all three
planes of motion. Indeed, recent research demonstrates that
the contribution of different muscle groups to lumbar spine
stability depends on the direction and magnitude of trunk
loading (10). The abdominal muscles control external forces
that may cause the spine to extend, laterally flex, or rotate
(2). The abdominals have also been reported to increase the
stability of the spine through co-contraction with the lumbar
extensors (2). Ireland (19) further suggests that the abdomi-
Address for correspondence: John D. Willson, MSPT, University of Del-
aware, Department of Physical Therapy, 305 McKinly Lab, Newark, DE
19716; E-mail: jdwillson@yahoo.com.
Submitted for publication November 2003.
Accepted for publication January 2004.
0195-9131/04/3606-0926
MEDICINE & SCIENCE IN SPORTS & EXERCISE®
Copyright © 2004 by the American College of Sports Medicine
DOI: 10.1249/01.MSS.0000128145.75199.C3
926
Leetun et al. AJSM 2004

Hip abduction isometric strength testing was performed
with subjects positioned in sidelying on a treatment table
(Fig. 1). A pillow was placed between the subjects’ legs,
using additional toweling as needed, such that the hip of the
leg to be tested was abducted approximately 10° as mea-
sured with respect to a line connecting the anterior superior
iliac spines. A strap placed just proximal to the iliac crest
and secured firmly around the underside of the table was
used to stabilize the subjects’ trunk. The center of the force
pad of a Nicholas hand-held dynamometer (Lafayette In-
struments, Lafayette, IN) was then placed directly over a
mark located 5 cm proximal to the lateral knee joint line.
This dynamometer uses a load cell force detecting system to
measure static force ranging from 0 to 199.9 kg with accu-
racy to 0.1 kg Ϯ 2%. The dynamometer was secured be-
tween the leg and a second strap that was wrapped around
the leg and the underside of the table. The strap eliminated
the effect of tester strength on this measure which has been
reported to be a limitation of hand-held dynamometry (4).
After zeroing the dynamometer, the subject was instructed
to push the leg upward with maximal effort for 5 s. The
force value displayed on the dynamometer was recorded and
the device was re-zeroed. One practice trial and three ex-
perimental trials were performed, with 15 s of rest between
trials. The peak value from the three experimental trials was
recorded. The athlete was then repositioned on their oppo-
site side to test the hip strength of the contralateral limb
using the same procedures.
Hip external rotation (ER) isometric strength testing was
performed with subjects positioned on a padded chair with
the hips and knees flexed to 90° (Fig. 2). To limit the contri-
bution of the hip adductors to force production in rotation, a
strap was used to stabilize the thigh of the involved leg and a
towel roll was placed between the subjects’ knees. The dyna-
mometer was then placed such that the center of the force pad
was directly over a mark that was 5 cm proximal to the medial
malleolus. A strap around the leg and around the base of a
stationary object held the dynamometer in place during con-
tractions. Collection of peak hip external rotation isometric
strength for each leg then proceeded in the same manner as that
for hip abduction strength.
Muscle capacity of the posterior core was measured using
the modified Biering-Sorensen test (30) (Fig. 3). The athlete
was positioned in prone with the pelvis at the edge of a
treatment table. Straps were used to secure the athletes’
pelvis and legs to the table. The athlete supported their torso
with their hands on a bench in front of the table until they
FIGURE 2—Isometric testing of hip external rotation strength using
hand-held dynamometry and strap stabilization.
FIGURE 1—Isometric testing of hip abduction strength using hand-
held dynamometry and strap stabilization.
928 Official Journal of the American College of Sports Medicine http://www.acsm-msse.org
Hip abduction isometric strength testing was performed
with subjects positioned in sidelying on a treatment table
(Fig. 1). A pillow was placed between the subjects’ legs,
using additional toweling as needed, such that the hip of the
leg to be tested was abducted approximately 10° as mea-
sured with respect to a line connecting the anterior superior
iliac spines. A strap placed just proximal to the iliac crest
and secured firmly around the underside of the table was
used to stabilize the subjects’ trunk. The center of the force
pad of a Nicholas hand-held dynamometer (Lafayette In-
struments, Lafayette, IN) was then placed directly over a
mark located 5 cm proximal to the lateral knee joint line.
This dynamometer uses a load cell force detecting system to
measure static force ranging from 0 to 199.9 kg with accu-
racy to 0.1 kg Ϯ 2%. The dynamometer was secured be-
tween the leg and a second strap that was wrapped around
the leg and the underside of the table. The strap eliminated
the effect of tester strength on this measure which has been
reported to be a limitation of hand-held dynamometry (4).
After zeroing the dynamometer, the subject was instructed
the modified Biering-Sorensen test (30) (Fig. 3). The athlete
was positioned in prone with the pelvis at the edge of a
treatment table. Straps were used to secure the athletes’
pelvis and legs to the table. The athlete supported their torso
with their hands on a bench in front of the table until they
FIGURE 2—Isometric testing of hip external rotation strength using
hand-held dynamometry and strap stabilization.
FIGURE 1—Isometric testing of hip abduction strength using hand-
held dynamometry and strap stabilization.
928 Official Journal of the American College of Sports Medicine http://www.acsm-msse.org
were instructed to cross their arms and assume a horizontal
position. The athlete was required to maintain the body in a
horizontal position for as long as possible. The total time
that the athlete was able to maintain the horizontal position
until they touched down on the bench in front of them with
their hands was recorded in seconds using a stopwatch.
Athletes performed the side bridge test as described by
McGill et al. (30) as a measure of lateral core muscle
This test was performed with the patient supine on the
treatment table with their hips flexed to 90° and their knees
fully extended. Patients were asked to steadily lower their
legs back to the table over a 10-s period while they main-
tained contact with the examiner’s hand at their L4–L5
interspace. A large board was placed behind the athlete
during this test with marks indicating 10° increments of hip
flexion. The angle at which the athlete’s low back raised
from the examiner’s hand was recorded. Lower angles of
hip flexion indicate a better performance on the test.
After 1 yr of testing, we questioned the sensitivity of the
straight leg lowering test for this population of subjects.
There was very little variability in the measurement as
nearly 70% of the athletes raised from the examiner’s hand
between 50° and 60° of hip flexion, making the effect size
small and increasing our likelihood of Type II error. There-
fore, subjects enrolled in the second year of testing per-
formed the flexor endurance test as described by McGill et
al. (30) This test is performed seated on a treatment table
with the athlete’s back supported on a 60° wedge (measured
from horizontal). The athlete’s hands were crossed over
their chest and their toes were placed under a stabilization
strap. The athletes were then asked to maintain the position
as the supporting wedge was pulled 10 cm away from the
athlete. The time the athlete was able to maintain the 60°
angle was recorded using a stopwatch. The test ended
FIGURE 3—Endurance testing of lumbar extensors using the modi-
fied Beiring-Sorensen test.
Isometric testing
of hip abduction
strength using
hand-held
dynamometry and
strap stabilization
Isometric testing
of hip external
rotation strength
using hand-held
dynamometry and
strap stabilization
Endurance testing of lumbar
extensors using the modified
Beiring-Sorensen test
were instructed to cross their arms and assume a horizontal
position. The athlete was required to maintain the body in a
horizontal position for as long as possible. The total time
that the athlete was able to maintain the horizontal position
until they touched down on the bench in front of them with
their hands was recorded in seconds using a stopwatch.
Athletes performed the side bridge test as described by
McGill et al. (30) as a measure of lateral core muscle
capacity, particularly the quadratus lumborum (Fig. 4). The
athletes were positioned in right sidelying with their top foot
in front of their bottom foot and their hips in zero degrees of
flexion. The athletes were asked to lift their hips off the
treatment table, using only their feet and right elbow for
support. The left arm was held across their chest with their
hand placed on the right shoulder. The total time the athlete
was able lift their bottom hip from the table was recorded
using a stopwatch. McGill (30) previously documented no
significant difference between right and left side bridge
endurance times. Therefore, the measure for the right lateral
core muscles was used for data analysis.
Anterior core muscle testing was performed using the
straight leg lowering test for the first year of testing (23).
fore, subjects enrolled
formed the flexor endur
al. (30) This test is per
with the athlete’s back s
from horizontal). The
their chest and their toe
strap. The athletes were
as the supporting wedge
athlete. The time the at
angle was recorded us
when the angle of the a
60° threshold. Based o
uted values, we found
indicator of anterior
straight leg lowering te
Injuries. The head at
participating in the stud
tremity injuries that oc
games throughout the se
event that occurred du
quired treatment or atten
doctor, or other medical
resulted in at least one f
participation. Trainers w
the details of each inju
(practice or game enviro
tact with another player
involved, and the type o
number of whole days l
each injury.
Data analysis. Core
pared between genders
and injury and those w
variance tests (SPSS 11
level of 0.05 was used
abdominal muscle perfo
descriptively but were n
due to the previously
associated lack of powe
sion was used to analy
status and postural musc
cess began with simultan
FIGURE 4—Endurance testing of the lateral trunk using the side
bridge test. Left side test position shown here.
FIGURE 3—Endurance testing of lumbar extensors using the modi-
fied Beiring-Sorensen test.
CORE STABILITY IN ATHLETES Medicin
Endurance testing of the lateral
trunk using the side bridge test
(left side test position)

the first prospective study to demonstrate a relationship
between these variables. However, several retrospective and
cross-sectional studies have been performed that previously
indicated that such a relationship may exist for a variety of
injuries (1,13,20,21). For example, Ireland et al. (20) iden-
tified significant weakness among young female athletes
However, in a m
isometric hip s
tion, are more a
injury than trun
These resul
versus enduran
TABLE 5. Comparison of core stability measures by injury status.
Hip Abduction
(% Body Weight)
Hip External Rotation
(% Body Weight)
Average (SD) Average (SD) Avera
Uninjured (N ϭ 99) 31.6 (7.1) 20.6 (4.2) 72.0
Injured (N ϭ 41) 28.6 (5.5) 17.9 (4.4) 64.7
P 0.02 0.001
CORE STABILITY IN ATHLETES
tion and internal rotation. Indeed, recent literature verifies
that females tend to display greater hip internal rotation and
adduction during athletic tasks (12,22,25).
Athletes who sustained an injury in this study displayed
significantly less hip abduction and external rotation
strength than uninjured athletes. To our knowledge, this is
the first prospective study to demonstrate a relationship
between these variables. However, several retrospective and
cross-sectional studies have been performed that previously
indicated that such a relationship may exist for a variety of
injuries (1,13,20,21). For example, Ireland et al. (20) iden-
tified significant weakness among young female athletes
maintain force
McGill et al.
endurance is g
erate force in
endurance of th
occurrence of l
However, in a m
isometric hip s
tion, are more a
injury than trun
These resul
versus endura
TABLE 5. Comparison of core stability measures by injury status.
Hip Abduction
(% Body Weight)
(% Body Weight)
Average (SD) Average (SD) Aver
Uninjured (N ϭ 99) 31.6 (7.1) 20.6 (4.2) 72.
Injured (N ϭ 41) 28.6 (5.5) 17.9 (4.4) 64.
P 0.02 0.001
CORE STABILITY IN ATHLETES
iterature verifies
rnal rotation and
study displayed
xternal rotation
nowledge, this is
e a relationship
retrospective and
d that previously
t for a variety of
et al. (20) iden-
female athletes
maintain force (endurance) in the lumbo-pelvic-hip complex.
McGill et al. (29) suggest that the value of trunk muscle
endurance is greater than the ability of these muscles to gen-
erate force in the prevention of low back pain. Indeed, the
endurance of the trunk extensors has been found to predict the
occurrence of low back pain among 30- to 60-yr-old adults (3).
However, in a more athletic population, this study suggests that
isometric hip strength measures, particularly in external rota-
tion, are more accurate predictors of back and lower extremity
injury than trunk endurance measures.
These results may reflect the significance of strength
versus endurance for individuals who participate in high
tus.
(% Body Weight) Side Bridge (s) Back Extension (s)
Average (SD) Average (SD) Average (SD)
20.6 (4.2) 72.0 (32.4) 128.3 (43.6)
17.9 (4.4) 64.7 (28.8) 121.6 (48.9)
0.001 0.22 0.43
Medicine & Science in Sports & Exerciseா 931
CORE STABILITY BY INJURY STATUS

LOGISTIC REGRESSION
INJURY STATUS AS DEPENDENT VARIABLE
s
s
n
h
.
n
dynamic test.
Future studies on the potential of core stability programs
to prevent serious knee ligament injuries also seem justified.
TABLE 8. Logistic regression results (dependent variable ϭ injury during
the season).
Variable Coefficient t P
Odds
Ratio (95% CI OR)
Constant 2.931 2.37 0.018
Hip abduction Ϫ0.031 Ϫ0.85 0.40 0.97 (0.90, 1.04)
Hip external rotation Ϫ0.146 Ϫ2.49 0.013 0.86 (0.77, 0.97)
Side bridge 0.007 0.73 0.46 1.01 (0.99, 1.02)
Back extension Ϫ0.004 Ϫ0.77 0.44 1.00 (0.99, 1.01)
Likelihood ratio [df] 12.72 [4] 0.013
% correct prediction 62.6%
McFadden’s-R2
0.076
http://www.acsm-msse.org

MULTICOMPONENT
INTERVENTIONS
THE 11+
• comprehensive warmup program
designed to reduce the risk of
injuries
Strength, plyometrics, balance
Plank, Side plank, Nordic hamstring, Single leg
balance, Squat, Jumping

RESEARCH
Comprehensive warm-up programme to prevent injuries
in young female footballers: cluster randomised
controlled trial
Torbjørn Soligard, PhD student,1
Grethe Myklebust, associate professor,1
Kathrin Steffen, research fellow,1
Ingar Holme, professor,1
Holly Silvers, physical therapist,2
Mario Bizzini, physical therapist,3
Astrid Junge,
associate professor,3
Jiri Dvorak, professor,3
Roald Bahr, professor,1
Thor Einar Andersen, associate
professor1
ABSTRACT
ObjectiveTo examinetheeffectofa comprehensive warm-
up programme designed to reduce the risk of injuries in
female youth football.
Design Cluster randomised controlled trial with clubs as
the unit of randomisation.
Setting 125 football clubs from the south, east, and
middle of Norway (65 clusters in the intervention group;
60 in the control group) followed for one league season
(eight months).
Participants 1892 female players aged 13-17 (1055
players in the intervention group; 837 players in the
control group).
Intervention A comprehensive warm-up programme to
improve strength, awareness, and neuromuscular control
during static and dynamic movements.
Main outcome measure Injuries to the lower extremity
(foot, ankle, lower leg, knee, thigh, groin, and hip).
Results During one season, 264 players had relevant
injuries: 121 players in the intervention group and 143 in
the controlgroup (rate ratio 0.71, 95% confidence interval
0.49 to 1.03). In the intervention group there was a
significantly lower risk of injuries overall (0.68, 0.48 to
0.98), overuse injuries (0.47, 0.26 to 0.85), and severe
injuries (0.55, 0.36 to 0.83).
Conclusion Though the primary outcome of reduction in
lowerextremityinjurydidnotreachsignificance,theriskof
severe injuries, overuse injuries, and injuries overall was
reduced. This indicates that a structured warm-up
programme can prevent injuries in young female football
players.
Trial registration ISRCTN10306290.
INTRODUCTION
Football (soccer) is the most popular team sport in the
world. There are already more than 265 million
registered players, and the number of participants is
continuing to grow.1
In particular, the number of
women players is increasing rapidly.1
Playing football,
however, entails a substantial risk of injury, and studies
on elite and non-elite female footballers have reported
rates of injury similar to those in men,2-11
the most
common being injuries to the knee and ankle ligament
and thigh muscle strains.2-9 11 12
Women might even be
at greater risk of serious injury than men; the rate of
anterior cruciate ligament injuries is three to five times
higher for girls than for boys.13 14
The high injury rate among football players in
general and female players in particular constitutes a
considerable problem for the player, the club, and—
given the popularity of the sport—for society at large.
Health consequences are seen not just in the short term
but also in the dramatic increase in the risk of early
osteoarthritis.15-17
Despite the urgent need to develop
programmes to prevent knee and ankle injuries in
footballers, there exist only a few small or non-
randomised studies on prevention of injury in female
football players.18-20
Inarecentrandomisedcontrolledtrial,weexamined
the effect of a structured training programme (“The
11”)21
over one season among 2000 female players
aged 13-17.22
The intervention consisted of exercises
focusing on core stability, balance, dynamic stabilisa-
tion, and eccentric hamstring strength. We found no
difference in the injury risk between the intervention
group and control group, though the study was limited
by low compliance among the intervention teams.
This led us to develop an exercise programme to
improve both the preventive effect of the programme
and the compliance of coaches and players. The
revised programme (“The 11+”) included key exer-
cises and additional exercises to provide variation and
progression. It also included a new set of structured
running exercises that made it better suited as a
comprehensive warm-up programme for training and
matches.
We conducted a randomised controlled trial to
examinetheeffectoftherevisedprogrammeonratesof
lower extremity injury in young female footballers. To
minimise contamination bias within clubs, we used a
cluster randomised design.
1
Oslo Sports Trauma Research
Centre, Norwegian School of
Sport Sciences, PO Box 4014
Ullevaal Stadion, 0806 Oslo,
Norway
2
Santa Monica Orthopaedic and
Sports Medicine Research
Foundation, 1919 Santa Monica
Blvd, Suite 350, Santa Monica,
CA 90404 USA
3
FIFA Medical Assessment and
Research Centre, Schulthess
Clinic, Lengghalde 2, CH-8008
Zurich, Switzerland
Correspondence to: T Soligard
torbjorn.soligard@nih.no
Cite this as: BMJ 2008;337:a2469
doi:10.1136/bmj.a2469
BMJ | ONLINE FIRST | bmj.com page 1 of 91476
A Randomized Controlled Trial to Prevent
Noncontact Anterior Cruciate Ligament
Injury in Female Collegiate Soccer Players
Julie Gilchrist,*†
MD, Bert R. Mandelbaum,‡
MD, Heidi Melancon,§
MPH,
George W. Ryan,
||
PhD, Holly J. Silvers,‡
MPT, Letha Y. Griffin,¶
MD, PhD,
Diane S. Watanabe,
‡
MA, ATC, Randall W. Dick,
#
MS, and Jiri Dvorak,** MD
From the
†
Division of Unintentional Injury Prevention, National Center for Injury Prevention &
Control, Centers for Disease Control & Prevention, Atlanta, Georgia,
‡
Santa Monica
Orthopedic & Sports Medicine Research Foundation, Santa Monica, California, the
§
National Recreation and Park Association, Ashburn, Virginia, the ||
Office of Statistics
and Programming, National Center for Injury Prevention & Control, Centers for Disease
Control & Prevention, Atlanta, Georgia,
¶
Peachtree Orthopedics, Atlanta, Georgia,
the
#
National Collegiate Athletic Association, Indianapolis, Indiana, and the
**Fédération Internationale de Football Association (FIFA), Medical Assessment and Research
Center, Schulthess Clinic, Zurich, Switzerland.
Background: Neuromuscular and proprioceptive training programs can decrease noncontact anterior cruciate ligament injuries;
however, they may be difficult to implement within an entire team or the community at large.
Hypothesis: A simple on-field alternative warm-up program can reduce noncontact ACL injuries.
Study Design: Randomized controlled trial (clustered); Level of evidence, 1.
Methods: Participating National Collegiate Athletic Association Division I women’s soccer teams were assigned randomly to
intervention or control groups. Intervention teams were asked to perform the program 3 times per week during the fall 2002 sea-
son. All teams reported athletes’ participation in games and practices and any knee injuries. Injury rates were calculated based
on athlete exposures, expressed as rate per 1000 athlete exposures. A z statistic was used for rate ratio comparisons.
Results: Sixty-one teams with 1435 athletes completed the study (852 control athletes; 583 intervention). The overall anterior
cruciate ligament injury rate among intervention athletes was 1.7 times less than in control athletes (0.199 vs 0.340; P = .198;
41% decrease). Noncontact anterior cruciate ligament injury rate among intervention athletes was 3.3 times less than in control
athletes (0.057 vs 0.189; P = .066; 70% decrease). No anterior cruciate ligament injuries occurred among intervention athletes
during practice versus 6 among control athletes (P = .014). Game-related noncontact anterior cruciate ligament injury rates in
intervention athletes were reduced by more than half (0.233 vs 0.564; P = .218). Intervention athletes with a history of anterior
cruciate ligament injury were significantly less likely to suffer another anterior cruciate ligament injury compared with control ath-
letes with a similar history (P = .046 for noncontact injuries).
Conclusion: This program, which focuses on neuromuscular control, appears to reduce the risk of anterior cruciate ligament
injuries in collegiate female soccer players, especially those with a history of anterior cruciate ligament injury.
Keywords: RCT; ACL; soccer; injuries
*Address correspondence to Julie Gilchrist, MD, CDC/NCIPC, Division of Unintentional Injury Prevention, 4770 Buford Hwy, MS F62, Atlanta, GA 30341
(e-mail: jrg7@cdc.gov).
Presented at the interim meeting of the AOSSM, San Francisco, California, March 2004.
Dr. Mandelbaum, Ms. Silvers, and Ms. Watanabe, employees of Santa Monica Orthopedic and Sports Medicine Research Foundation (SMOSMRF),
were involved with the development of the PEP Program under evaluation in this study but have no financial interest in the PEP Program and did not
participate in data collection or analysis. Ms. Melancon was employed by the SMOSMRF and participated in data collection and analysis.
The American Journal of Sports Medicine, Vol. 36, No. 8
DOI: 10.1177/0363546508318188
© 2008 American Orthopaedic Society for Sports Medicine
Soligard et al. BMJ 2008Gilchrist et al. AJSM 2008
~50% reduction of risk for non contact LE injuries
how much is due to core stability components?

Performance aspects of an injury prevention program: a ten-week
intervention in adolescent female football players
K. Steffen, H. M. Bakka, G. Myklebust, R. Bahr
Department of Sports Medicine, Oslo Sports Trauma Research Center, Norwegian School of Sport Sciences, Oslo, Norway
Corresponding author: Kathrin Steffen, Department of Sports Medicine, Oslo Sports Trauma Research Center, Norwegian
School of Sport Sciences, P.O. Box 4014 Ulleva˚l Stadion, 0806 Oslo, Norway. Fax: 147 23 26 23 07, E-mail:
kathrin.steffen@nih.no
Accepted for publication 10 May 2007
The injury rate in football is high, and effective injury
prevention methods are needed. An exercise program, the
‘‘11,’’ has been designed to prevent the most common injury
types in football. However, the effect of such a program on
performance is not known. The aim of this randomized-
controlled trial was to investigate the effect of the ‘‘11’’ on
performance after a 10-week training period. Thirty-four
adolescent female football players were randomly assigned
to either an intervention (n 5 18) or a control group
(n 5 16). The ‘‘11’’ is a 15-min program consisting of ten
exercises for core stability, lower extremity strength, bal-
ance and agility. Performance tests included isokinetic and
isometric strength protocols for the quadriceps and ham-
strings, isometric hip adduction and abduction strength,
vertical jump tests, sprint running and soccer skill tests.
There was no difference between the intervention and
control groups in the change in performance from the pre-
to post-test for any of the tests used. In conclusion, no effect
was observed on a series of performance tests in a group of
adolescent female football players using the ‘‘11’’ as a
structured warm-up program.
Background
Football is probably the most popular sport world-
wide, with a growing interest and an increasing
number of female players in particular (Norwegian
Football Association, 2005). It is a contact sport and
challenges physical fitness by requiring a variety of
skills at different intensities. Running is the predo-
minant activity, and explosive efforts during sprints,
duels, jumps and kicks are important performance
factors, requiring maximal strength and anaerobic
power of the neuromuscular system (Wisløff et al.,
1998; Cometti et al., 2001; Reilly & Gilbourne, 2003;
Hoff & Helgerud, 2004).
Unfortunately, the game is associated with a high
risk of injuries, which results in significant costs for
the public health system (de Loes et al., 2000) and
may even cause long-term disability for the injured
player (Lohmander et al., 2004; von Porat et al.,
2004; Myklebust & Bahr, 2005). Serious knee inju-
ries, such as anterior cruciate ligament injuries, are of
particular concern in female team sports (Powell &
Barber-Foss, 2000; Myklebust et al., 2003; Agel et
al., 2005; Olsen et al., 2005). Consequently, there is
every reason to emphasize the prevention of injuries
in football, and to develop and implement prevention
programs for young players as early in their career as
possible.
Several programs have successfully incorporated
one or more exercise components, including plyo-
metrics, strength, neuromuscular training, running
and cutting movement patterns, to prevent injuries in
female (Hewett et al., 1999; Heidt et al., 2000;
Myklebust et al., 2003; Mandelbaum et al., 2005;
Olsen et al., 2005) and male athletes (Askling et al.,
2003). However, compliance is a concern (Myklebust
et al., 2003), and it may be difficult to motivate
coaches and players to follow such exercise programs
merely to prevent injuries, unless there is a direct
effect performance benefit as well.
Exercises used in prevention protocols have also
been shown to have performance effects among male
football players, such as increased strength (Askling
et al., 2003; Mjølsnes et al., 2004). Core stability
exercises may improve technical skills and total
awareness of the game (Holm et al., 2004; Leetun
et al., 2004; Paterno et al., 2004). Comprehensive
neuromuscular training programs that combine plyo-
metrics, core strengthening, balance, resistance or
speed/agility training may improve several measures
of performance concomitantly and at the same time
improve biomechanical measures related to lower
Scand J Med Sci Sports 2008: 18: 596–604 Copyright & 2007 The Authors
Journal compilation & 2007 Blackwell MunksgaardPrinted in Singapore .All rights reserved
DOI: 10.1111/j.1600-0838.2007.00708.x
596
PERFORMANCE
ENHANCEMENT?
• No significant effects were
observed on different
performance variables among
players participating in a 10-
week injury prevention program,
compared with players who
trained as usual
more intense training stimulus
needed?
34 adolescent female football
players from two elite sport high
schools
Steffen et al. SJMSS 2008

HEALTH BENEFITS VS HEALTH RISK
Type and amount of activity
Novice
runners
Recreational
Runners
males
Recreational
Runners
females
Competitive
runners
Marathon
runners
2.56
2.55-2.60
2.06
2.02-2.10
1.80
1.70-1.90
1.55
1.54-1.56
1.10
1.09-1.20
Tonoli et al. 2010

• General preventive approach lies
in reducing the load or
increasing loading capacity to
reduce risk for RRI
• However ... specific loads leading
up to RRI are biomechanically
different and caused by local
overloading
• An individual set of weak links
that predispose to injury?
OVERLOADING THE
SYSTEM?

ILL-LOADING?
914 | december 2011 | volume 41 | number 12 | journal of orthopaedic & sports physical therapy
[ CASE REPORT ]
P
atellofemoral pain (PFP) is one of the most common overuse
injuries of the lower extremity. It affects 10% to 20% of the
general population18
and is associated with higher risk of injury
in active females.34
The findings of a previous study suggested
that a history of PFP increases the risk for subsequent development of
patellofemoral osteoarthritis.35
The nature of PFP is multifactorial, and
many risk factors have been associated with this condition.5,10
Locally,
imbalance of the quadriceps muscula-
ture25
and maltracking of the patella24
are 2 potential factors that may lead to
STUDY DESIGN: Case series.
BACKGROUND: Patellofemoral pain is a com-
mon overuse injury in runners. Recent findings
suggest that patellofemoral pain is related to high-
impact loading associated with a rearfoot strike
pattern. This case series describes the potential
training effects of a landing pattern modification
program to manage patellofemoral pain in runners.
CASE DESCRIPTION: Three female runners
with unilateral patellofemoral pain who initially
presented with a rearfoot strike pattern underwent
8 sessions of landing pattern modification program
using real-time audio feedback from a force sensor
placed within the shoe. Ground reaction forces
during running were assessed with an instru-
mented treadmill. Patellofemoral pain symptoms
were assessed using 2 validated questionnaires.
Finally, running performance was measured by
self-reported best time to complete a 10-km
run in the previous month. The runners were
assessed before, immediately after, and 3
months following training.
OUTCOMES: The landing pattern of runners
was successfully changed from a rearfoot to a non-
rearfoot strike pattern after training. This new pat-
tern was maintained 3 months after the program.
The vertical impact peak and rates of loading were
shown to be reduced. Likewise, the symptoms
related to patellofemoral pain and associated
functional limitations were improved. However,
only 1 of the participants reported improved
running performance after the training.
DISCUSSION: This case series provided
preliminary data to support further investigation
of interventions leading to landing pattern
modification in runners with patellofemoral pain.
LEVEL OF EVIDENCE: Therapy, level 4.
J Orthop Sports Phys Ther 2011;41(12):914-919,
Epub 25 October 2011. doi:10.2519/jospt.2011.3771
KEY WORDS: biofeedback, gait retraining,
impact peak, impact rate, landing pattern
1
Research Associate, Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hung Hom, Hong Kong, China; Postdoctoral Fellow, Department of Physical
Medicine and Rehabilitation, Harvard Medical School, Harvard University, Cambridge, MA. 2
Director, Spaulding National Running Center, Department of Physical Medicine and
Rehabilitation, Harvard Medical School, Harvard University, Cambridge, MA. The experimental protocol of this study was reviewed and approved by The Ethics Review Committee
of the Hong Kong Polytechnic University. Address correspondence to Dr Roy Cheung, Spaulding National Running Center, Department of Physical Medicine and Rehabilitation,
Harvard Medical School, Harvard University, Cambridge, MA 02138. Email: RTCheung@partners.org
ROY T.H. CHEUNG, PT, PhD1
• IRENE S. DAVIS, PT, PhD2
Landing Pattern Modification
to Improve Patellofemoral Pain
in Runners: A Case Series
PFP. Through the linkage of the kine-
matic chain, hip muscle weakness11,29
and
excessive foot pronation20
have also been
proposed to lead to the development of
PFP. Therefore, different treatment ap-
proaches6,11
have been evaluated in the
management of PFP.
Running is a popular sport worldwide.
According to an epidemiological study,36
the overall annual rate of running injury
ranges from 37% to 56%. The incidence
rate, calculated according to running
time, is between 2.5 to 12.1 injuries per
1000 hours of running, with the knee
being the most vulnerable joint. Among
those knee injuries, PFP is the most
common condition. PFP in runners has
been linked to abnormal lower extremity
movement patterns4,22
and weaknesses
of hip muscles.33
However, the role of
abnormal kinetics in the development of
PFP has not been fully examined. Verti-
cal impact loading has been associated
with a number of conditions, including
plantar fasciitis,27
tibial stress fractures,28
and knee osteoarthritis.13,23
A recent pi-
lot study suggested that runners with a
history of PFP may exhibit a higher im-
pact peak and loading rate than healthy
runners.9
Approximately 75% of runners make
initial contact with the ground using a
rearfoot strike pattern (ie, they land on
their heels).12
This rearfoot strike pattern
results in a very distinct vertical impact
peak, which may be eliminated or signifi-
Original article
Br J Sports Med 2011;45:691–696. doi:10.1136/bjsm.2009.069112 691
Accepted 19 January 2010
Published Online First
28 June 2010
ABSTRACT
Background Patellofemoral pain syndrome (PFPS)
is the most common overuse injury in runners. Recent
research suggests that hip mechanics play a role in the
development of this syndrome. Currently, there are no
treatments that directly address the atypical mechanics
associated with this injury.
Objective The purpose of this study was to deter-
mine whether gait retraining using real-time feedback
improves hip mechanics and reduces pain in subjects
with PFPS.
Methods Ten runners with PFPS participated in this
study. Real-time kinematic feedback of hip adduction
(HADD) during stance was provided to the subjects as
they ran on a treadmill. Subjects completed a total of
eight training sessions. Feedback was gradually removed
over the last four sessions. Variables of interest included
peak HADD, hip internal rotation (HIR), contralateral pel-
vic drop, as well as pain on a verbal analogue scale and
the lower-extremity function index. We also assessed
HADD, HIR and contralateral pelvic drop during a single
leg squat. Comparisons of variables of interest were
made between the initial, final and 1-month follow-up
visit.
Results Following the gait retraining, there was a
significant reduction in HADD and contralateral pelvic
drop while running. Although not statistically significant,
HIR decreased by 23% following gait retraining. The
18% reduction in HADD during a single leg squat was
very close to significant. There were also significant
improvements in pain and function. Subjects were able
to maintain their improvements in running mechanics,
pain and function at a 1-month follow-up. An unexpected
benefit of the retraining was an 18% and 20% reduc-
tion in instantaneous and average vertical load rates,
respectively.
Conclusions Gait retraining in individuals with PFPS
resulted in a significant improvement of hip mechan-
ics that was associated with a reduction in pain and
improvements in function. These results suggest that
interventions for PFPS should focus on addressing the
underlying mechanics associated with this injury. The
reduction in vertical load rates may be protective for
the knee and reduce the risk for other running-related
injuries.
INTRODUCTION
Running is one of the most popular forms of
exercise in the USA. Annually, 50–85% of runners
will sustain an injury.1 2 Of these injures, patell-
ofemoral pain syndrome (PFPS) is the most com-
monlyreported.3 PFPSoftenbecomeschronic,with
up to 91% of individuals reporting continued knee
pain 4–18 years after being initially diagnosed.4
In addition, recent research suggests that having a
history of PFPS increases the risk of later develop-
ing patellofemoral osteoarthritis (OA).5
The aetiology of PFPS is multifactorial in nature.
Most investigators agree that PFPS is related, in
part, to faulty lower-extremity mechanics. In
particular, there is growing scientific support
for the relationship between hip mechanics and
patellofemoral joint mechanics. In an early cadav-
eric study, Huberti et al reported that increasing
the Q-angle (which would be associated with
increased hip adduction (HADD)) resulted in
greater contact pressure on the lateral aspect of
the patella.6 In a more recent cadaveric study, Li
et al demonstrated that increasing femoral inter-
nal rotation resulted in greater lateral patellar con-
tact pressure.7 Over time, the repetitive exposure
to these motions may damage the cartilage and
lead to greater stress on the highly innervated
subchondral bone.8 9
There is also emerging evidence that altered hip
kinematics during dynamic activities are present
in individuals with PFPS. For example, a recent
study has found greater peak hip internal rotation
(HIR) during running in individuals with PFPS.10
In addition, Willson et al reported that individu-
als with PFPS run, jump and squat with greater
HADD compared with healthy controls.11 They
also found greater contralateral pelvic drop across
activities.11 Finally, a recent prospective study
has found that runners who developed PFPS had
greater HADD compared with their healthy
counterparts.12
Several investigators have examined the effect
of hip abductor and external rotation strength-
ening on PFPS.13 14 While they have reported
improvements in hip strength and reductions in
knee pain, most have lacked any follow-up beyond
the completion of the treatment. However, in a
study by Blønd et al, it was reported that 80% of
individuals who had engaged in a strengthening
programme continued to have pain 5 years later.
In addition, 74% had to reduce their physical
activity as a result of pain.15 This suggests that
the underlying mechanics were not addressed
directly.
There is increasing evidence that individuals
can successfully alter their gait mechanics using
real-time feedback.16–18 19 As an example, White
et al studied a group of individuals with a unilat-
eral hip replacement and associated reduced load-
ing on their involved side.16 After 8 weeks of gait
retraining using real-time force feedback from an
1Division of Physical Therapy,
University of Kentucky,
Lexington, Kentucky, USA
2University of Delaware,
Newark, Delaware, USA
Correspondence to
Dr Brian Noehren, Division of
Physical Therapy, University of
Kentucky, Wethington Bldg rm
204D, 900 S, Limestone Road,
Lexington, KY 40536-0200,
USA;
bwn51@yahoo.com
The effect of real-time gait retraining on hip
kinematics, pain and function in subjects with
patellofemoral pain syndrome
B Noehren,1 J Scholz,2 I Davis2
06_bjsports69112.indd 69106_bjsports69112.indd 691 6/8/2011 9:28:14 PM6/8/2011 9:28:14 PM

OUTCOMES
• As a result of fatigue novice
runners display changes in ...
trunk flexion and extension
hip extension
ankle pronation
• Trunk kinematics appear to be
significantly affected during
fatigued running and should not
be overlooked
Koblbauer et al. JSAMS 2013

translating and transferring
fundamental and efficacious
evidence into practical
prevention strategies
epidemiological
guidelines
biomechanical and
impact through high
compliance and proper use
of effective measures
translating and transferring
effectiveness evidence into
biomechanical experiments
unravelling the underlying
pathways by which
measures prevent injury

MYTH OR REALITY
DOES IT MATTER?
• Of course it matters, but the
discussion seems to revolve
around fundamental approaches
What is CS
Can we measure CS?
Which measures are affected by CS?
Is there a theoretical background to
CS?
...

Myth or legend?
It doesn’t matter to have this
discussion on a fundamental
level if there is no clinical
effectiveness to support the
practical use of CS

With current clinical
knowledge CS appears to be
a myth
Weak correlations between
CS and performance
measures
Weak predictive value of CS
in regards to injury risk
Weak outcomes due to
methodological issues?
Myth or legend?

With
current
clinical
knowledge

CS
could
become
a
legend
Posi8ve
outcomes
when
CS
is

employed
in
LBP
management
In
novice
or
recrea8onal

athletes
there
is
room
to
CS

improvement
providing
hooks

for
preven8on
Myth or legend?

Evert Verhagen
www.slhamsterdam.com
@evertverhagen
e.verhagen@vumc.nl

Core stability training: Does it improve sports performance

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