The contribution of leg press and knee extension strength and power to physical function in people with knee osteoarthritis: A cross-sectional study.
The purposes of this study were to 1) determine the additional contributions of leg press and knee extensor power, over and above that of strength, to the performance of physical function tasks in people with knee osteoarthritis, and 2) compare the ability of bilateral leg press to unilateral knee extensor strength and power to predict functional task performance.


METHODS
A cross-sectional, exploratory study of 40 individuals with tibiofemoral knee osteoarthritis resulting in moderate impairments in physical function was conducted. Physical function (Get-up and Go, timed stair climb and descent, and five time chair rise) and muscle performance (leg press and knee extension strength and power) were assessed.


RESULTS
After controlling for covariates and strength, leg press, but not knee extensor, power explained additional variance in physical function (11% and 21%). Conversely, adding strength to regression models including covariates and power did not consistently improve the prediction of physical function. Additionally, leg press power consistently explained more variance in physical function (44 to 57%) than involved (24 to 34%) or uninvolved (28 to 48%) knee extension power.


CONCLUSIONS
Leg press power may be a more functionally relevant measure of muscle performance than knee extension strength in this population. Future studies should investigate the effectiveness of interventions specifically designed to improve leg press power in people with knee osteoarthritis.
Department of Rehabilitation Sciences, University of Toledo, 2801 W. Bancroft Street, MS #119, Toledo, OH 43606-3390, USA. Electronic address: tevaldm@arcadia.edu.
Michael A
MA
Tevald
Department of Rehabilitation Sciences, University of Toledo, 2801 W. Bancroft Street, MS #119, Toledo, OH 43606-3390, USA. Electronic address: Amanda.murray@ucdenver.edu.
Amanda M
AM
Murray
Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, 209 Fetzer Hall, CB#8700, Chapel Hill, NC 27599-8700, USA. Electronic address: bluc@live.unc.edu.
Brittney
B
Luc
Department of Orthopaedic Surgery, University of Toledo Orthopaedic Center, Health Science Campus, 125 Hospital Drive, MS #1904, Toledo, OH 43614, USA. Electronic address: Kafai.lai@utoledo.edu.
Kafai
K
Lai
Department of Orthopaedic Surgery, University of Toledo Orthopaedic Center, Health Science Campus, 125 Hospital Drive, MS #1904, Toledo, OH 43614, USA. Electronic address: David.sohn@utoledo.edu.
David
D
Sohn
Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, 209 Fetzer Hall, CB#8700, Chapel Hill, NC 27599-8700, USA. Electronic address: pietrosi@email.unc.edu.
Brian
B
Pietrosimone
D000368:Aged; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D053580:Muscle Strength; D020370:Osteoarthritis, Knee / Q000503:physiopathology*; D016059:Range of Motion, Articular; D013647:Task Performance and Analysis
Arthritis; Muscle strength; Outcome assessment; Rehabilitation