The energy expenditure and hence energy requirements of 12 young Chinese gymnasts attending a specialized school in Beijing were assessed. Total energy expenditure was measured using the doubly labeled water technique and this, in conjunction with measures of basal metabolic rate (BMR), allows the calculation of a physical activity level (PAL). Mean PAL value for the gymnasts was 1.98, which is significantly different from published mean values found in nongymnast children of a similar age. This mean value is equivalent to very heavy levels of physical activity during the periods of training being undertaken. This is the first time that energy expenditure has been noninvasively measured in free-living young gymnasts. The data will be of use to sports scientists and nutritionists alike.

No abstract

Activable enriched stable isotopes can play a unique role in studies of nutritional status, metabolism, absorption rates, and bioavailability of minerals. As a practical example, eight juvenile athletes were selected to test the absorption rates of iron during training and non-training periods by enriched stable isotope of Fe-58 (enriched degree: 51.1%) via activation analysis Fe-58 (n,γ) Fe-59 of the collected feces samples. The results indicated that the average iron absorption rates of the juvenile athletes with and without training are 9.1 ± 2.8 and 11.9 ± 4.7%, respectively, which implies that the long-term endurance training with high intensity makes the iron absorption rate of athletes lower. In the meantime, the comparison of the activable enriched isotope technique with atomic absorption spectrometry was performed, which showed that the former was better than the latter in reliability and sensitivity. It is because this nuclear method can distinguish the exogenous and endogenous iron in the samples, but not for non-nuclear methods.