Assessment of the bone quality of black female athletes using quantitative ultrasound

Aim. The mean daily calcium intake of adult Nigerians is reportedly low, and animal studies have shown that exercise-induced changes in the bones of growing mice are gender specific. We therefore sought to describe calcaneal broadband ultrasound attenuation (BUA), speed of sound (SOS), stiffness index (SI) and SI-based T-scores in a cohort of Nigerian female athletes; to assess the correlation of SI with energy expenditure; and to compare mean SI values between sports. Methods. We recruited 52 female athletes in 10 sporting categories, and recorded their anthropometric data. Activity levels were estimated using a questionnaire. Bone density was assessed using calcaneal ultrasound. Results. The mean age of athletes was 21 +/- 4 years (range 15-39 years). The mean body mass index (BMI) was 22.0 +/- 3.5 kg/m(2), and was not different between the sub-group of footballers/runners (21.3 +/- 1.7 kg/m(2)) and other athletes (23.1 +/- 4.8 kg/m(2), P=0.06). The mean energy expenditure was 32.2 +/- 9.5 kcal/kg/ day, and was not different between the sub-group of footballers/runners (30.8 +/- 9.2 kcal/kg/day) and other athletes (34.3 +/- 9.7 kcal/kg/day, P=0.19). The mean BUA of the athletes was 135 +/- 14 dB/MHz, the mean SOS was 1597 +/- 13 m/s, the mean SI was 118 +/- 15, and the median SI-based T-score was +1.1 (-1.6 to +3.53). The means of all ultrasound parameters were not significantly different between footballers/runners and other sportswomen. Conclusion. Consistent physical training may improve calcaneal SI of black females by one, and potentially by as much as three T-score units. Training intensity, rather than the qualitative aspects of a sport, appears to be a major determinant of SI in female Nigerian athletes.