We compared body mass index (BMI), body fat, and skeletal muscle mass between (1) a mixed-sex nonathletic cohort of people with patellofemoral pain (PFP) and pain-free people, and (2) a nonathletic cohort of people with PFP and pain-free people subgrouped by sex (i.e., men and women with PFP vs. pain-free men and women).
This cross-sectional study included 114 people with PFP (71 women, 43 men) and 54 pain-free controls (32 women, 22 men). All participants attended a single testing session to assess body composition measures, which included BMI, percentage of body fat (%BFBioimpedance), and skeletal muscle mass (both assessed by bioelectrical impedance analysis), and percentage of body fat (%BFSkinfold) (assessed by skinfold caliper analysis). A one-way univariate analysis of covariance (age and physical activity levels as covariates) was used to compare body composition measures between groups (i.e., PFP vs. pain-free group; women with PFP vs. pain-free women; men with PFP vs. pain-free men).
Women with PFP presented significantly higher BMI, %BFBioimpedance, and %BFSkinfold, and lower skeletal muscle mass compared to pain-free women (p ≤ 0.04; effect size = ‒0.47 to 0.85). Men with PFP and men and women combined had no differences in BMI, %BFBioimpedance, %BFSkinfold, and skeletal muscle mass compared to their respective pain-free groups (p > 0.05).
Our findings indicate that BMI and body composition measures should be considered as part of the evaluation and management of people with PFP, especially in women, who have demonstrated higher BMI and body fat and lower skeletal muscle mass compared to pain-free controls. Future studies should not assess body composition measures in a mixed-sex population without distinguishing men participants from women participants.
The prevalence of overweight and obesity has been growing alarmingly across the world.1 In the past four decades, the number of adults with obesity worldwide has increased more than 6 times (100 million in 1975 to 671 million in 2016),1 whereas 1.3 billion adults (1 in 4) were considered overweight in 2016.1,2 Despite increasing the predisposition to multiple comorbidities,3,4 overweight and obesity are also detrimental to the musculoskeletal system,5, 6, 7 likely via both systemic and mechanical effects.8,9 Systemic effects include the production by adipose tissue of adipokines such as leptin10 and the amplification of the inflammation profile through an increase in the production of interleukin-611 and tumor necrosis factor-alpha.12 Both of these systemic changes are associated with deleterious effects to patellar cartilage (e.g., reduced patellar cartilage volume) and pain.13,14 Mechanically, the one joint most affected by overweight and obesity is the patellofemoral joint, which is subjected to loads 2 to 11 times bodyweight during stair ascent, squatting, and running activities.15, 16, 17