Differences in distal lower extremity tissue masses and mass ratios exist in athletes of sports involving repetitive impacts.

This study aimed to examine the effects of sex and sport on the tissue composition of the distal lower extremity of varsity athletes, in sports that involve repetitive-impact loading patterns. Fat mass, lean mass, bone mineral content and wobbling mass were predicted for the leg and leg + foot segments of varsity basketball, cross-country, soccer and volleyball athletes. The absolute masses were normalised to body mass, and also expressed relative to each other as ratios. Females and males differed on most normalised tissue masses and ratios by 11-101%. Characteristic differences were found in the normalised tissue masses across sports, with the lowest and highest values displayed by cross-country and volleyball (female)/basketball (male) athletes, respectively. Conversely, cross-country athletes had the highest wobbling mass:bone mineral content and lean mass:bone mineral content ratios for females by 10% and 16%, respectively. The differences between sports may be explained in part by different impact loading patterns characteristic of each sport. Tissue mass ratio differences between sports may suggest that the ratios of soft to rigid tissues are optimised by the body in response to typical loading patterns, and may therefore be useful in investigations of distal lower extremity injury mechanisms in athletes.