the association between trunk, hip, and knee function … · different trunk, hip, and knee emg...
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THE ASSOCIATION BETWEEN TRUNK, HIP, AND KNEE FUNCTION AND
PERFORMANCE DURING A SINGLE-LEG SQUAT TEST Lori Bolgla, Eric Booth, Kaitlyn K. Browning, & Brianne Lapierre
Department of Physical Therapy, Georgia Regents University, Augusta, GA
BACKGROUND
PURPOSE/HYPOTHESES
METHODS
Upon arrival, subjects performed three plank exercises to assess anterior, lateral, and posterior core endurance.
RESULTS
CONCLUSIONS
The purpose of this study was to compare 1) trunk endurance, 2)
hip and knee strength, and 3) trunk, hip, and knee neuromuscular
activity in individuals who demonstrate good or poor SLS
performance.
Hypotheses: 1) Subjects with “poor” SLS performance will exhibit
decreased trunk endurance and decreased hip and knee strength.
2) Subjects with “poor” or “good” SLS performance will generate
different trunk, hip, and knee EMG activity during the SLS.
The knee is the most commonly injured lower extremity joint,
particularly among active individuals.
Core stability may influence the occurrence of certain knee
pathologies, such as anterior cruciate ligament injury,
patellofemoral pain, and iliotibial band syndrome.
Core stability has both active and passive components. Passive
components include bony and ligamentous structures, while active
components include the trunk, hip, and knee musculature.
The single-leg squat (SLS) is a common functional screening tool
used to examine gross lower extremity (LE) strength and
kinematics during dynamic movement.
To date, researchers have not simultaneously compared trunk, hip,
and knee strength and EMG activity during a SLS between
individuals who demonstrate “good” or “poor” SLS performance. .
Early identification of the active core impairments that influence
SLS performance can provide a means for targeted knee injury
prevention programs and knee rehabilitation protocols.
All subjects, regardless of SLS performance, demonstrated similar
core endurance, strength, and EMG activity during the SLS.
Higher level motor control, not strength, may contribute more to an
individual’s ability to correctly perform a SLS.
Activity specific motor control training may be needed to alter
underlying hip and knee pathomechanics.
Future studies should focus on developing protocols that integrate
motor control principles for knee injury prevention and rehabilitation
programs.
SINGLE-LEG SQUAT
REFERENCES
0
10
20
30
40
50
60
70
80
90
100
Hip Extension Hip Abduction Knee Extension
Pe
rce
nt
Bo
dy M
as
s (
%)
Strength
Poor
Good
0
20
40
60
80
100
120
140
160
180
200
Anterior Core Lateral Core Posterior Core
Ave
rag
e T
ime
(s
ec
)
Core Endurance
Poor
Good
Poor Performance
Knee-Medial-To-Foot
Good Performance
Knee-Over-Foot
SUBJECTS Ageberg, E., Bennell, K. L., Hunt, M. A., Simic, M., Roos, E. M., & Creaby, M. W.
(2010). Validity and inter-rater reliability of medio-lateral knee motion observed during a
single-leg limb mini squat. BMC Musculoskeletal Disorders, 11(265), 1-8.
DiMattia, M. A., Livengood, A. L., Uhl, T. L., Mattacola, C. G., & Malone, T. R. (2005).
What are the validity of the single-leg squat test and its relationship to hip-abduction
strength? Journal of Sport Rehabilitation, 14, 108-123.
Powers, C. M. (2010). The influence of abnormal hip mechanics on knee injury: a
biomechanical perspective. Journal of Orthopaedic & Sports Physical Therapy, 40(2),
42-51.
Willy, R.D., Davis, I.S. (2011). The effect of the hip-strengthening program on
mechanics during running and during a single-leg squat. Journal of Orthopaedic and
Sports Physical Therapy, 41(9), 625-632.
29 recreationally-active healthy adults (11 men, 18 women)
Age = 24.31 ± 1.51 y, Height = 174.03 ± 9.69 cm, Mass = 68.57 ±
10.97 kg
Exclusion Criteria: problems with balance, exercise restrictions, any
significant lower extremity or spinal injury or surgery
* P: poor performance;
G: good performance
† Expressed as 100%
of maximum voluntary
isometric contraction
^ Level of significance
at p = 0.05
EMG Data
Anterior Plank
Strength data was recorded for the gluteus maximus, gluteus medius, and rectus femoris using hand-held dynamometry.
Surface EMG electrodes were applied to the rectus abdominis,
abdominal obliques, lumbar extensors, gluteus maximus, gluteus medius, and rectus femoris to collect EMG activity during the SLS.
Subjects performed 5 repetitions of the SLS. An overall score of
good was received if the subject maintained knee-over-foot position ≥ 3 times.
Data was analyzed using independent t-tests to identify
between-group (good or poor performance) differences.
Lateral Plank Posterior Plank