BONE MASS CHANGES IN FEMALE COLLEGIATE ATHLETES RELATED TO MENSTRUAL CYCLE AND TRAINING SEASONS 786

Abstract

As part of an ongoing longitudinal study, we report bone mineral density(BMD) changes in the lumbar spine (LS), hip (including femoral neck, trochanteric, and Ward's sites), forearm (ultradistal (UD) and one-third proximal radius), and whole body (including arms, legs, trunk and pelvis) at a point in the training cycle which was 4.90±0.92 months (mean±SD) after baseline BMD measures. The subjects are competitive female track (Tr, n=12), tennis (T, n=5), soccer (S, n=14), volleyball (VB, n=6), and golf (G, n=6) athletes, and non-athletic control women (C, n=12). At the time of the second BMD measures, Tr. T and G were pre- or inseason, while VB and S were off-season. BMD was assessed by dual-energy x-ray absorptiometry (DXA). The age at menarche was not different among groups, and the incidence of oligo- and amenorrhea (OA) was low: 3 Tr and 2 S, and 1 C. There was no effect(p>0.05) of menstrual cycle on bone mass changes at any site. There were no group differences for% change BMD at the LS, any hip site, forearm, or whole body (including legs, trunk and pelvis). The% change for armsBMD was different among groups (p=0.05); VB tended to lose bone mass in the arms(-4.1±5.6%) as compared to zero (no change in BMD), while the other groups either maintained or gained BMD at this site. VB showed an increase in legsBMD (1.2±1.1%, p<0.05) compared to zero over this time period. Soccer lost bone mass at the LS (-1.6±2.4%) and left UD forearm(-1.6±2.7%) (p<0.05). Controls also had a loss of LSBMD(-1.6±1.8%, p=0.01). No other group or BMD site changed significantly over this brief time period. Part of this bone mass loss may be explained by the training seasons of these athletic groups. During the winter and spring seasons, VB and S are in their off-season and training intensity and volume are greatly reduced, compared to Tr, T and G, who are training more at this time of year. Future measures of BMD may further support this data and the concept that BMD changes are affected by seasonal training.