Relationship of Hip and Trunk Muscle Function with Single Leg Step-Down Performance: Implications for Return to Play Screening and Rehabilitation.
OBJECTIVE
Evaluate the relationship of hip and trunk muscle function with the Single Leg Step-Down test (SLSD).


METHODS
Laboratory study.


METHODS
Biomechanics Laboratory.


METHODS
71 healthy participants with no history of anterior cruciate ligament (ACL) or lower extremity injury in the last 3 months completed this study (38 males, 33 females; mean 25.49 ± 0.62 years).


RESULTS
Hip abduction (HABD), external rotation (HER), and extension (HEXT) peak isometric force were measured. Trunk endurance was measured with plank (PL) and side plank (SPL) tests. SLSD repetitions in 60-s and dynamic knee valgus (VAL) were recorded.


RESULTS
PL, SPL, HABD, HER, and HEXT were positively correlated with SLSD repetitions. PL (r = 0.598, p < 0.001) was most correlated with SLSD repetitions, and regression demonstrated that PL (p = 0.001, R2= 0.469) was a predictor of SLSD repetitions. VAL trended toward negative correlation with PL and SPL. Sex-specific differences were present, with PL, SPL, HABD, and HER showing stronger relationships with SLSD in females.


CONCLUSIONS
Hip and trunk muscle function were positively correlated with SLSD performance, and these relationships were strongest in females. PL predicted performance on the SLSD. Further research is needed to investigate the utility of SLSD as a screening or return-to-play test for lower extremity conditions such as ACL injury and patellofemoral pain.
Department of Orthopaedic Surgery and Sports Medicine, University of Kentucky, 740 S. Limestone, K401, Lexington, KY, United States. Electronic address: jeremy.m.burnham@gmail.com.
Jeremy M
JM
Burnham
Department of Orthopaedic Surgery and Sports Medicine, University of Kentucky, 740 S. Limestone, K401, Lexington, KY, United States. Electronic address: Michael.yonz@uky.edu.
Michael C
MC
Yonz
BioMotion Laboratory, Division of Physical Therapy, College of Health Sciences, University of Kentucky, 900 S. Limestone, Lexington, KY, United States. Electronic address: ke.robertson@yahoo.com.
Kaley E
KE
Robertson
BioMotion Laboratory, Division of Physical Therapy, College of Health Sciences, University of Kentucky, 900 S. Limestone, Lexington, KY, United States. Electronic address: rachelle.mckinley@uky.edu.
Rachelle
R
McKinley
Department of Orthopaedic Surgery and Sports Medicine, University of Kentucky, 740 S. Limestone, K401, Lexington, KY, United States. Electronic address: wilso.ben@uky.edu.
Benjamin R
BR
Wilson
Department of Orthopaedic Surgery and Sports Medicine, University of Kentucky, 740 S. Limestone, K401, Lexington, KY, United States. Electronic address: dljohns@uky.edu.
Darren L
DL
Johnson
Department of Orthopaedic Surgery and Sports Medicine, University of Kentucky, 740 S. Limestone, K401, Lexington, KY, United States. Electronic address: mlirel2@uky.edu.
Mary Lloyd
ML
Ireland
BioMotion Laboratory, Division of Physical Therapy, College of Health Sciences, University of Kentucky, 900 S. Limestone, Lexington, KY, United States. Electronic address: b.noehren@uky.edu.
Brian
B
Noehren
D000328:Adult; D001265:Athletic Injuries / Q000503:physiopathology / Q000517:prevention & control; D001696:Biomechanical Phenomena; D005260:Female; D064368:Healthy Volunteers; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology; D000068958:Return to Sport; D012399:Rotation; D012737:Sex Factors; D013909:Thorax / Q000502:physiology*; D019415:Torque
ACL; Hip; Return to play; Sex differences; Step down; Trunk