Influence of Diet plus Hypoxic Training on Bone Health in Overweight and Obese Adolescents

Objective: To explore the effects of diet plus hypoxic training on bone health in overweight and obese adolescents.Methods: Healthy overweight or obese adolescents who was born and living in the plain took part in the intervention camp and were divided into plain training group or hypoxic training group(living high-training low and high group, altitude≈2 300 m), the intervention last for four weeks. The normoxic group lived in plain and exercised six days per week under normoxia. The hypoxic group slept in simulated ≈2 300 m nomobaric hypoxia from 19:00 to next morning and trained 2 hours under the same hypoxia in the daytime, but other arrangements were the same as the plain group. Diet was controlled based on the resting metabolic rate. Target exercise intensity was set at low-intensity aerobic range. Body mineral content(BMC) and body mineral density(BMD) were measured by dual energy X-ray absorption. Results: 1) After 4 weeks intervention, only the total BMC of the normoxic group exhibited a significant increase(+1.85%,P=0.006). No interaction effect existed between two groups. 2) Total BMD was increased in these two groups, and a significant interaction effect was observed between groups. Compared with the plain group, the elevation of the BMD was lower in the hypoxic group(+3.09% vs +1.29%, P=0.011,η2=0.176). 3) After 4-weeks intervention, a significant increase in BMD of the spine was observed only in the normoxic group(P=0.025). 4) A significant interaction effect was existed between the two groups in the serum visfatin level(normoxic group vs. hypoxic group:+31.87% vs-18.76%, P=0.033, η2=0.143).5) The changes of serum visfatin level was negatively correlated with the changes of total BMD(P=0.04, r=-0.37), but positively correlated with the changes of trunk fat mass(P=0.02, r=0.38). Conclusions: A 4-week diet combined with hypoxic training intervention reduced body mass and body fat mass effectively; meanwhile, the total BMD increased. The intervention didn't exert negative effect on bone health. However, hypoxia induced some side effects on BMD and visfatin may play an important role in those response.