Effect Of Long-Term High-Intensity Interval Training On Serum 25(Oh)D(3)Concentrations In Elderly Adults

Higher levels of physical activity and cardiorespiratory fitness are positively related to serum 25(OH)D3 concentrations; however, the response of 25(OH)D3 concentrations to chronic high-intensity interval training is unclear. PURPOSE: To compare the effects of a 12-week high-intensity interval training (HIIT), and moderate-intensity continuous training (MICT) on serum 25(OH)D3 concentrations in elderly people. METHODS: Twenty-nine sedentary older adults (18 male and 11 female) with a mean age of 64.8 ± 3.9 years were randomly divided into a sedentary control group (SC, n = 9), HIIT group (four 3-min, 90% of maximal oxygen uptake, n = 10) and MICT group (25 min, 70% of maximal oxygen uptake, n = 10) for 12 weeks. Serum 25(OH)D3concentrations were determined at baseline, mid and post training. Bone mineral density and maximal oxygen uptake (VO2max) were determined at baseline and post training. RESULTS: Twelve weeks of HIIT and MICT improved VO2max (4.19 ± 2.21 and 1.84 ± 1.63 ml/kg/min, respectively, p < 0.005). Significant seasonal reduction in serum 25(OH)D3 concentrations was found in the SC and MICT groups (p < 0.05, respectively) while no changes was found in the HIIT group. The change in serum 25(OH)D3 concentrations was negatively related to the change in bone mineral density in SC group (r = -0.825; p = 0.006). CONCLUSIONS: The results of our study suggest that 12 weeks of high-intensity interval training could inhibit the seasonal reduction in serum 25(OH)D3 concentrations.