Effects of progressive resistance strength training on knee biomechanics during single leg step-up in persons with mild knee osteoarthritis

Abstract

Background: The goal of this study was to determine if increasing strength in primary knee extensors and flexors would directly affect net knee joint moments during a common functional task in persons with knee osteoarthritis.

Methods: An exploratory single sample clinical trial with pre-post treatment measures was used to study volunteers with clinical diagnosis of mild knee osteoarthritis (OA) in one knee. Subjects participated in an individually supervised training program 3 times a week for eight weeks consisting of progressive resistive exercises for knee extensors and knee flexors. Pre and post training outcome assessments included: 1. Net internal knee joint moments, 2. Electromyography of primary knee extensors and flexors, and 3. Self-report measures of knee pain and function. The distribution of lower extremity joint moments as a percent of the total support moment was also investigated.

Findings: Pain, symptoms, activities of daily life, quality of life, stiffness, and function scores showed significant improvement following strength training. Knee internal valgus and hip internal rotation moments showed increasing but non-statistically significant changes post-training. There were no significant differences in muscle co-contraction activation of the Quadriceps and Hamstrings.

Interpretation: While exercise continues to be an important element of OA management, the results of this study suggest improvements in function, pain, and other symptoms, as a result of strength training may not be causally related to specific biomechanical changes in net joint moments.

Copyright © 2011 Elsevier Ltd. All rights reserved.

Figures

Figure 1

Subject Set up with reflective markers and Instrumented step

Figure 2

Average net internal knee joint moments pre = before strength training program and post = after strength training program for involved side F/E= knee flexion/extension, V/V = knee Varus/Valgus (n=18).

Figure 3

Average net internal hip joint moments pre = before strength training program and post = after strength training program for involved side (n=18). F/E= flexion extension, I/E = internal/external hip rotation, Add/Abd = hip adduction/abduction