The Effect of an Acute Bout of Exercise on Circulating Vitamin D Metabolite Concentrations: A Randomised Crossover Study in Healthy Adults

The effect of acute exercise on circulating concentrations of vitamin D metabolites is unclear. To address this knowledge gap, we examined the effect of a bout of treadmill-based exercise versus rest on circulating concentrations of 25(OH)D₃, 25(OH)D₂, 3-epi-25(OH)D₃, 24,25(OH)₂D₃, 1,25(OH)₂D₃, and vitamin D₂ and D₃ in healthy men and women. Thirty-three healthy adults (14 females, 41 (15) y, body mass index 26.2 (3.7) kg/m², V̇ O_{2 MAX} 36.2 (9.2) mL/kg/min; mean (SD)) completed two laboratory visits involving 60 minutes of moderate intensity treadmill exercise (60% V̇ O_{2 MAX}) versus 60 minutes of seated rest, both in an overnight fasted-state, as part of a randomised crossover design. Venous blood samples were drawn at baseline, immediately (0-hour), 1-hour and 24 hours after the exercise- or restperiod. There was a significant time x trial interaction effects for total circulating 25(OH)D (p=0.0148), 25(OH)D₃ (p=0.0127) and 1,25(OH)₂D₃ (p=0.0226). Immediately post-exercise, 25(OH)D, 25(OH)D₃, and 1,25(OH)₂D₃ concentrations were significantly elevated compared to the control resting condition, and 1,25(OH)₂D₃ remained significantly elevated one hour later. Circulating albumin, DBP, calcium and PTH were elevated immediately post-exercise. Thus, an acute bout of moderate intensity exercise transiently increases concentrations of
circulating 25(OH)D and 1,25(OH)₂D₃ compared to resting conditions.