Swimmers tend to have greater body fat than athletes from other sports. The purpose of the study was to examine changes in body composition after altitude hypoxia exposure and the role of blood distribution to the skeletal muscle in swimmers. With a constant training volume of 12.3 km/day, young male swimmers (N = 10, 14.8 ± 0.5 years) moved from sea-level to a higher altitude of 2,300 meters. Body composition was measured before and after translocation to altitude using dual-energy X-ray absorptiometry (DXA) along with 8 control male subjects who resided at sea level for the same period of time. To determine the effects of hypoxia on muscle blood perfusion, total hemoglobin concentration (THC) was traced by near-infrared spectroscopy (NIRS) in the triceps and quadriceps muscles under glucose-ingested and insulin-secreted conditions during hypoxia exposure (16% O2) after training. While no change in body composition was found in the control group, subjects who trained at altitude had unequivocally decreased fat mass (-1.7 ± 0.3 kg, -11.4%) with increased lean mass (+0.8 ± 0.2 kg, +1.5%). Arterial oxygen saturation significantly decreased with increased plasma lactate during hypoxia recovery mimicking 2,300 meters at altitude (~93% versus ~97%). Intriguingly, hypoxia resulted in elevated muscle THC, and sympathetic nervous activities occurred in parallel with greater-percent oxygen saturation in both muscle groups. In conclusion, the present study provides evidence that increased blood distribution to the skeletal muscle under postprandial condition may contribute to the reciprocally increased muscle mass and decreased body mass after a 3-week altitude exposure in swimmers.

In this study, we determined the cross-generation link between sedentary behavior of schoolchildren with their 6-year BMI progression pattern and metabolic disease category of their parents. Anthropometric data of 11,190 elementary schoolchildren (aged 13) were retrospectively tracked from 2003 to 2009, and classified into two groups: Normal (N = 9793) and Metabolic Disorders (N = 1397), based on the disease category of their parents (under at least one medication for stroke, coronary heart disease (CAD), diabetes, and hypertension). Schoolchildren's weekly time spending on reading, computer use, video game, music listening, radio listening, TV watching, and movie watching, was reported with parental assistance via questionnaires. Baseline BMI and 6 years BMI progression rate in Metabolic Disorders group were significantly higher than those in Normal group. In particular, offsprings from stroke parents exhibited the greatest baseline BMI across 6 years compared to the rest of the disease categories. For Metabolic Disorders group, time spending on computer use, video game, TV watching, and music listening of schoolchildren was significantly longer than Normal group. Reading, which occupied the largest portion of weekly sedentary time, was not contributed to the group difference on the BMI status of schoolchildren. The current study demonstrates that schoolchildren from family with at least one parent having metabolic disorders, particularly stroke, tend to be more sedentary and heavior than their age-matched normal peers. School-based obesity prevention programs are suggested for this specific group by restricting time spent on technology-associated sedentary behaviors and promoting sport activities.