Body fat and skeletal muscle mass predict knee strength and pain in young women with patellofemoral pain

Abstract

Introduction: Patellofemoral pain (PFP) is a chronic dysfunction, with a high prevalence in young women and characterized by complaints of recurrent pain and a poor long-term prognosis. With a multifactorial characteristic, recent studies point to a possible association between body composition and PFP outcomes, however the results are still unclear. Objective: to investigate whether there is an association between BMI, skeletal muscle mass and body fat with physical function, knee strength and pain in women with PFP. Methods: Twenty-four women, aged between 18 and 35 years, diagnosed with PFP, were recruited for this study. Body fat and skeletal muscle mass were quantified using tetrapolar bioimpedance systems. Pressure hyperalgesia was evaluated using an algometer. Maximal strength during concentric contraction of the knee extensors was measured with an isokinetic dynamometer. Objective function assessment included the single-leg hop test, step-down test, single-legged chair stand test, and side hop. The Pearson correlation test was utilized, with a significance level set at p < 0.05. Results: Significant negative correlations were found between BMI and body fat with knee extensor torque. There was a positive correlation between skeletal muscle mass and knee extensor torque. For objective function, there was a negative correlation between body fat and performance in the side hope, single leg hop test and stair climbing test. Local pressure hyperalgesia was associated with skeletal muscle mass and body fat. Conclusion: Body composition should be factored into the evaluation and management of young women with PFP, as it correlates with deficiencies in functional performance, muscle torque, and pain.