The effect of calcium supplementation on bone calcium balance and calcium and bone metabolism during load carriage in women: a randomised controlled crossover trial

• Published in: Journal of bone and mineral research 2025-01
• Main Authors: Coombs, Charlotte V, Greeves, Julie P, Young, Christina D, Irving, Alice S, Eisenhauer, Anton, Kolevica, Ana, Heuser, Alexander, Tang, Jonathan C Y, Fraser, William D, O'Leary, Thomas J
• Format: Article
• Language: English
• ISSN: 0884-0431; 1523-4681; 1523-4681
• DOI: 10.1093/jbmr/zjaf004

Calcium supplementation before exercise attenuates the decrease in serum calcium and increase in PTH and bone resorption. This study investigated the effect of calcium supplementation on calcium and bone metabolism during load carriage in women. Forty-eight women completed two load carriage sessions (load carriage 1 n = 48; load carriage 2 n = 40) (12.8 km in 120 min carrying 20 kg) 60 min after consuming either 1000 mg calcium (Calcium) or nothing (Control) in a randomised order. Pre- and post-exercise urine samples were analysed for calcium isotope ratio (δ44/42Ca). Fasted blood samples were taken before (pre-exercise), during (0, 20, 40, 60, 80, 100, 120 min), and after (+15, +30, +60, +90 min) exercise and analysed for markers of calcium and bone metabolism. There was no effect of load carriage or supplementation on urine δ44/42Ca (P≥.110). Serum δ44/42Ca did not change with load carriage in Control (P=.617) but increased in Calcium (P=.003) and was higher at 120 min in Calcium vs Control (P=.018). Ionised calcium (iCa) decreased from pre-exercise to all exercise time-points (P