Elite-Level Female Distance Runners Experience Few Changes in Body Composition, Weight, and Bone Density Over a 5-Year Period

Abstract

Increased physical activity participation in elite-level female distance runners has been associated with increased values for total bone mineral density (TBMD) and spine BMD (SBMD) when compared to sedentary age-matched women. Little information exists regarding the dynamics of this increase during the competitive years and there are reports that menstrual irregularity in this population may place bone health at risk. PURPOSE: To examine the change in TBMD and SBMD and their relationship to age, body weight (WT), body fat percent (BF%), and fat-free mass (FFM) over a 5-year period in top-level female distance runners. METHODS: Fifteen international-class women distance runners (800m through marathon) were evaluated over a 5-year period in the Laboratory for Elite Athlete Performance using Georgia State University IRB-approved protocols. Subjects were regularly assessed on SBMD and TBMD, BF%, FFM (Lunar dPXL, Software version 1.5), and WT (balance beam scale) over a 5-year period. These athletes were provided suggestions on how to improve nutrient and energy intake so as to optimize body weight, body composition, bone density, and performance, and to sustain menstrual regularity. RESULTS: The average age of the athletes at the beginning of the study was 24.9 yr (± 3.88), and mean height was 168.3 cm (±4.24), mean WT was 55.08 kg (±4.81), mean FFM was 45.66 kg (±3.42), and mean BF% was 12.41 % (±3.17). Over the 5-year assessment period, runners experienced a significant increase in SBMD (p=.021), but no significant changes in WT, FFM, BF%, or TBMD. CONCLUSIONS: These athletes displayed a remarkable stability in the measured values, with the increase in spine BMD as the only significant change. The weight and body composition stability suggests that these athletes were dynamically matching energy and nutrient requirements, a fact that is likely to also help female athletes sustain menstrual regularity and bone health.