An investigation was conducted to clarify both the effect of water polo training on bone mass and the effect of training-induced menstrual disorders on bone. The subjects were 12 female college water polo players and 7 age-matched sedentary college women as a control group.
Menstrual condition was evaluated by 12 montes of basal body temperature measurement. Seven of the water polo players were eumenorrheic, and five had training-dependent (reversible) menstrual disorders (two with amenorrhea and three with cycle disturbances) .
Bone mineral measurement revealed differences between the water polo players and the sedentary women. The eumenorrheic water polo players had a higher bone mineral density (BMD) in the lumbar spine and total body skeleton than the sedentary control group, being 11.2% and 11.3% higher, respectively.
Effects of menstrual disorders (including cycle disturbance) were clear in the water polo players. The BMD of water polo players with menstrual disorders was 9.8% and 9.6% lower in the total body and lumbar spine that of eumenorrheic water polo players.
Hormonal examinations revealed a lower serum estradiol level in water polo players with menstrual disordsers in comparison with eumenorrheic water polo playes. Serum estradiol level showed a positive correlation with both total body BMD (r=0, 78, p<0.01) and lumbar spine BMD (r=0.71, p<0.01) .