Prouteau and colleagues (5), in their recent paper, repeatedly suggest that bone health and the effects of weight cycling on bone metabolism in judoists have not been investigated before. This is not entirely correct. In 1996, Nader (4) devoted an editorial comment to some of the work we previously had presented on metabolic changes in elite female judoists. We showed that strenuous training that included weight loss led to a state of relative hypoestrogenemia, menstrual problems, and increased bone and muscle breakdown (2). Also, Kayal et al. (3) and Baeyens (1) had reported stress fractures and increased muscular injuries in those female judoists in whom hypoestrogenemia was present, often as a consequence of weight cycling. These findings made us wonder whether only female judoists were at risk for negative changes in bone metabolism that may be associated with weight cycling though they are, in fact, caused by hypoestrogenemia rather than by the weight cycling itself.
We are excited to hear that Prouteau and colleagues (5) were able to further some of our work by studying both female and male judoists and that, in doing so, they had access to much improved scientific methods compared with us 14 yr ago. In addition to measuring serum C-terminal telopeptide of type-I collagen (CTX) and osteocalcin, the authors determined bone mineral density by DEXA. It is unclear, however, whether the authors truly performed DEXA more than a single time in each subject. In the absence of any repetitive DEXA measurements during the entire testing period bridging the weight loss and weight gain period, the DEXA data offer little additional insight into the specific effects of weight cycling on bone health. A single measurement that observes a bone mineral density in judo athletes higher than in controls mostly reflects the positive results of long-time judo practice, not of acute weight cycling.
Furthermore, the study by Prouteau et al. (5) shows that during their subjects' first in-weight competition of the season (i.e., after weight loss), values of CTX were significantly increased (P < 0.0001), as shown in their Figure 1. Because the figure does not discriminate between males and females, I am assuming that the same phenomenon was observed in both genders. Furthermore, the baseline concentrations of CTX, as obvious from the authors' Table 2, show significantly higher values only in those judoists who were female. Although Prouteau et al. (5) seem to suggest that the effects of weight cycling on bone parameters do not differ between genders, I am not convinced that such is entirely true. Note that 35% of their female subjects were taking oral contraceptives, hence partly mimicking the commonly observed weight-cycling-induced hypoestrogenemia that might affect bone turnover. It would be interesting to reprocess some of the data separating those from females not taking oral contraceptives from those who did. Without this further information, it is difficult to judge whether the results by Prouteau et al. are in agreement with, or actually contradict, our earlier findings on bone and muscle markers in female judoists.
Carl De Crée
1. Baeyens, L. Gynecological problems in young athletes (in French). Rév. Méd. Brux.
2. De Crée, C., R. Lewin, and A. Barros. Hypoestrogenemia and rhabdomyolysis (myoglobinuria) in the female judoist: a new worrying phenomenon? J. Clin. Endocrinol. Metab.
3. Kayal, D., M. L'Hermite-Balériaux, and L. Baeyens. Advantages of hormonal contraception for the athlete. Free communication on the Annual Reunion of the FGWO on Sports Medicine and Sports Sciences, Charleroi, June 19, 1993 [abstract]. In: Werken van de Belgische Vereniging voor Sportgeneeskunde en Sportwetenschappen.
4. Nader, S. Female judoists: their hormones, muscles and bones. Lancet
5. Prouteau, S., A. Pelle, K. Collomp, L. Benhamou, and D.Courteix. Bone density in elite judoists and effects of weight cycling on bone metabolic balance. Med. Sci. Sports Exerc.