Differences in Bone Strength Indices between Trained Male and Female Athletes Competing in the Same Sport: A pQCT Study

Abstract

Up to 10% of sport injuries are attributed to acute fractures. Reports indicate that females may be more susceptible to certain types of skeletal injuries when compared to males. In sedentary populations, differences do exist in specific bones indices between males
and females. One potential explanation for this susceptibility may be the differences in bone architecture and strength between males and females. The influence of the mechanical loading on the skeletal adaptation has been established. Environments that are dynamic, weight bearing, and incorporate high impact and repetitive movements are
associated with increased bone mass and bone strength at loaded anatomic sites. Given that mechanical loading is an essential modifier of bone architecture, it is less clear if
gender differences in bone indices (e.g., strength), previously reported in sedentary populations, will also remain consistent when studying trained athletes. By using pQCT, this study examined bone structure and volumetric density that allowed for the identification of the structural and densitometric underpinnings of bone strength differences in the selected athletic populations. A total of 111 trained collegiate-aged female and male ice hockey (21 female, 19 male), swimming (17 female, 13 male), and running (22 female, 19 male) athletes and 34 non-active controls (19 female, 15 male) were included in the study. Peripheral quantitative computed tomography (pQCT, Stratec XCT 3000) was used to examine bone that structures included total bone area, cortical density, section modulus, muscle cross-sectional area, and bone strength index of the dominant tibia. The results indicate that bone strength remained significantly higher (14-18%, P<0.05) in males who participated in weight-bearing sports (i.e., ice hockey and running) compared to their female counterparts. At the distal tibia, male ice hockey and running athletes had a greater bone strength index compared to females in that same sport (18.5% and 25.1%, respectively). In addition, at the tibia mid-shaft, male hockey players and runners exhibited significantly greater section modulus (10.7% and 17.8%) compared to the females. Differences in bone strength were primarily due to a greater total bone area. Interestingly, no significant differences in bone outcomes were evident among the male and female swimmers, despite males being taller and heavier