Frontal and transverse plane hip kinematics and gluteus maximus recruitment correlate with frontal plane knee kinematics during single-leg squat tests in women.
BACKGROUND
Hip muscle dysfunction may be associated with knee valgus that contributes to problems like patellofemoral pain syndrome. The purpose of this study was to (1) compare knee and hip kinematics and hip muscle strength and recruitment between "good" and "poor" performers on a single-leg squat test developed to assess hip muscle dysfunction and (2) examine relationships between hip muscle strength, recruitment and frontal plane knee kinematics to see which variables correlated with knee valgus during the test.


METHODS
Forty-one active women classified via visual rating as "good" or "poor" performers on the test participated. Participants completed 5-repetition single-leg squat tests. Isometric hip extension and abduction strength, gluteus maximus and gluteus medius recruitment, and 3-dimensional hip and knee kinematics during the test were compared between groups and examined for their association with frontal plane knee motion.


RESULTS
"Poor" performers completed the test with more hip adduction (mean difference=7.6°) and flexion (mean difference=6.3°) than "good" performers. No differences in knee kinematics, hip strength or hip muscle recruitment occurred. However, the secondary findings indicated that increased medial hip rotation (partial r=0.94) and adduction (partial r=0.42) and decreased gluteus maximus recruitment (partial r=0.35) correlated with increased knee valgus.


CONCLUSIONS
Whereas hip muscle function and knee kinematics did not differ between groups as we'd hypothesized, frontal plane knee motion correlated with transverse and frontal plane hip motions and with gluteus maximus recruitment. Gluteus maximus recruitment may modulate frontal plane knee kinematics during single-leg squats.
Program in Physical Therapy, the Department of Physical Medicine & Rehabilitation and Sports Medicine Center, Mayo Clinic, Rochester, MN, USA. Electronic address: hollman.john@mayo.edu.
John H
JH
Hollman
Program in Physical Therapy, the Department of Physical Medicine & Rehabilitation and Sports Medicine Center, Mayo Clinic, Rochester, MN, USA.
Christy M
CM
Galardi
Program in Physical Therapy, the Department of Physical Medicine & Rehabilitation and Sports Medicine Center, Mayo Clinic, Rochester, MN, USA.
I-Hsuan
IH
Lin
Program in Physical Therapy, the Department of Physical Medicine & Rehabilitation and Sports Medicine Center, Mayo Clinic, Rochester, MN, USA.
Brandon C
BC
Voth
Program in Physical Therapy, the Department of Physical Medicine & Rehabilitation and Sports Medicine Center, Mayo Clinic, Rochester, MN, USA.
Crystal L
CL
Whitmarsh
D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005260:Female; D006615:Hip / Q000502:physiology*; D006801:Humans; D007717:Knee / Q000502:physiology*; D007866:Leg / Q000502:physiology; D009068:Movement / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D009142:Musculoskeletal Physiological Phenomena; D016059:Range of Motion, Articular / Q000502:physiology; D011999:Recruitment, Neurophysiological / Q000502:physiology; D012399:Rotation; D012727:Sex Characteristics; D013848:Thigh / Q000502:physiology; D055815:Young Adult
Biomechanics; Electromyography; Hip; Knee; Lower extremity; Muscle strength