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Document Type

Article

Abstract

The purpose of this study was twofold: 1) to describe total body water (TBW ) values in premenarcheal athletes and nonathletes; and 2) to compare measured TBW determined by the deuterium oxide method with TBW estimated from the Mellits and Cheek formula [TW = —10.313 + 0.252 (WT) + 0.154 (HT)] in premenarcheal athletes and nonathletes. As a group the athletes (N = 73) averaged 2.72ℓ more measured TBW (22.66 ± 4.78ℓ vs 19.94 ± 4.43ℓ, p < .001) than the controls (N = 55), and 3.1% more of their body weight was composed of water (TBW%BW) when compared to the controls (62.8 ± 4.0% vs 59.9 ± 5.0%, p < .001). TBW showed a linear positive relationship with age, weight, and height for both athletes and controls. TBW%BW showed a tendency to decrease linearly in relation to age in the controls, but exhibited a positive linear increase in the athletes. F tests revealed that both the slopes (F = 3.2, df = 2/122 p < .0 5), and the intercepts (F = 12.1, df = 1/124, p < .01) of the regression equations for the prediction of TBW for the athletes [TBW = -11.354 + 0.433 (WT) + 0.126 (HT)] and controls [TBW = -10.656 + 0.351 (WT) + 0.133 (HT)] from height and weight were significantly different. T-test analyses revealed that TBWℓ determined experimentally and predicted from the Mellits and Cheek formula were significantly different for the athletes (22.66 ± 4.78ℓ vs 21.11 ± 3.5ℓ, p < .001) but not the controls (19.94 ± 4.43ℓ vs 19.79 ± 3.56ℓ, p > .05). The Mellits and Cheek formula has been used extensively by Frisch and her colleagues in the development and support of the “critical fat threshold” hypothesis for the triggering of menarche. The current results, in which TBW is consistently underestimated in young athletic females, invalidate the use of this technique with premenarcheal athletes.

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