Jockeys have lower bone mass than general population
MedWire News: Professional jockeys have an overall lower bone mass than either amateur boxers or a control group, study findings indicate.
Both jockeys and boxers need to carefully maintain a certain weight, and it has been proposed that the cycles of weight loss in jockeys could possibly lower bone mass. In addition, jockeys need to constantly keep weight down due to a regular racing schedule, while boxers only "weigh in" 12 hours before a bout and have a shorter competition season.
Eimear Dolan (Dublin City University, Ireland) and colleagues compared the bone mass of 58 professional jockeys (n=30), amateur boxers (n=14), and age-, body mass index-, and gender-matched controls (n=14). Measurements of bone mass, including bone mineral density (BMD), were taken via dual energy X-ray absorptiometry scanning.
As reported in the Journal of Bone and Mineral Metabolism, the jockeys had a significantly lower bone content than either the boxers or the controls, in terms of total body BMD and total body bone mineral content (BMC) minus the head. The boxers had the highest BMD of the three groups.
The researchers found that the main predictors of total BMC were height and lean mass, with lean mass having the most significance. They note that jockeys often keep chronic levels of low energy availability, which may impair the development of bone mass. Jockeys are also often susceptible to race-related fractures, and the low BMD noted among them in this study may be a major contributing factor. In contrast, boxing is a high-impact, high-intensity sport, and its activities and training requirements promote BMD development.
These findings support others that have noted a possible allometric relationship between lean and bone mass. The authors conclude that "further research may be required so to identify the interaction of genetic and lifestyle factors which may have influenced bone mass findings observed within the present study."
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By Stephanie Leveene