Urine Specific Gravity is Unrelated to BIA or Skinfold- Derived Body Fat Percent, But Is Related to Weight in Professional Racehorse Jockeys.

Abstract

Racehorse jockeys are known to be under stress to sustain standard weight so as to meet specific racing requirements. Nevertheless, there are few published data on whether strategies used to sustain the desired weight have an impact on health and body composition. PURPOSE: So as to investigate whether weight-sustaining strategies have an impact on health risk and body composition, urine specific gravity (USG) and anthropometric measures were obtained as part of a larger study assessing health and nutrition in racehorse jockeys. METHODS: Jockeys were assessed at three professional racetracks on typical race days using Georgia State University IRB approved protocols. Data included anthropometric, body composition, blood, urine, health history, and dietary intake data. This abstract reports on the relationship between USG and body fat percent (BF%), predicted from bioelectrical impedance analysis (BIA) and skinfolds, and weight (WT). RESULTS: We assessed 53 jockeys (males=47; females=6) on fasting USG, BF%, and WT. Mean age was 33.7 yr (± 10.43) for the males (M) and 33.6 yr (± 9.34) for the females (F). The study population was predominantly Caucasian (35.2%) and Hispanic (53.7%) with a few Asian-and African-Americans. Normal USG range is 1.002 to 1.028. The mean USG was 1.0207 (± .00752) in M and 1.0200 (± .00300) in F. Mean M weight was 52.8kg (± 2.09) and 48.7kg (± 2.04) in F. None of the F had USG outside the normal range and only 6 of the M had USG above 1.028. There was no relationship between USG and either method for predicting BF%, for M or for F. M with high USG had significantly higher weight (54.2kg vs. 52.1kg; p=.001) than those with normal USG, but there was no relationship between USG and either method for predicting BF%, even when assessing only those jockeys with high (>1.028) USG. CONCLUSIONS: These data suggest that female jockeys are at lower risk for poor hydration than male jockeys. Although most jockeys (n=42) had USG within the normal range, those with high USG (n=6) were significantly heavier. Heavier jockeys, therefore, may be more likely to resort to dehydration strategies to achieve the desired race weight. In no case was BF%, predicted from both BIA and skinfolds, associated with USG.