Factors which affect the menstrual cycle in the female track athletes

The purpose of this study was to find what factors were significant predictors of menstrual irregularity in young female track athletes. Thirty-four female track athletes with an age range of 18-22 years served as the subjects for the study. In order to qualify for the study, subjects must have been involved in competitive track for at least the last two years and have never taken oral contraceptives. The hypothetical predictors included in the model were: (1) percent body fat, (2) iron intake in mg per kg of body weight, (3) calcium intake in mg, (4) percent body fat intake, and (5) menarche age. The results of a maximum Rsquare and stepwise regression analysis showed that percent body fat and iron intake together accounted for 56% of the variance in menstrual cycles (adjusted R-square = .56). A backwards elimination procedure reported that calcium intake, percent fat intake, and menarche age accounted for only 1.68% of the variance in menstrual cycles when these three variables were removed from the models (adjusted Partial Rsquare = .0168). A one-way ANOVA for the variables percent body fat between menstrual cycle groups (amenorrheic 0-5 cycles a year, oligomenorrheic 6-11 cycles a year and eumenorrheic 12 cycles a year) showed a significant difference between groups. Newman Keuls Post Hoc Test showed the difference to be between the irregular (amenorrheic) and regular (eumenorrheic) and between the irregular (oligomenorrheic) and regular (eurnenorrheic) group. Additional analysis indicated the same pattern of results between the three groups for iron intake (measured in mg per kg of body weight). It was concluded that low percent body fat and low iron intake levels are the two strongest contributors to menstrual irregularity in young female track athletes.