Calcium and vitamin D intake timing may affect how bone adapts to exercise

Taking calcium and vitamin D before exercise may influence how bones adapt to exercise, according to a new study.

The study lead author Vanessa D. Sherk, PhD, postdoctoral research fellow at the University of Colorado Anschutz Medical Campus, the timing of calcium supplementation, and not just the amount of supplementation, may be an important factor in how the skeleton adapts to exercise training.

In the study, which included 52 men aged 18 to 45 years, investigators found that an exercise-induced decrease in blood calcium occurred whether calcium supplements were taken before or after exercising.

Pre-exercise supplementation, however, resulted in less of a decrease.

Although not statistically significant, parathyroid hormone levels increased slightly less among cyclists who took calcium before exercising.

"Taking calcium before exercise may help keep blood levels more stable during exercise, compared to taking the supplement afterwards, but we do not yet know the long-term effects of this on bone density," Sherk said.

The timing of calcium supplementation did not cause a difference in blood levels of a compound that is a biological indicator of bone loss.

Both the before- and after-exercise groups exhibited 50-percent increases in the level of this compound, called CTX, for collagen type-1 C-telopeptide.

The study will be presented at The Endocrine Society's 95th Annual Meeting in San Francisco.