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  • The effects of a calcium-ri...
    Haakonssen, Eric C; Ross, Megan L; Knight, Emma J; Cato, Louise E; Nana, Alisa; Wluka, Anita E; Cicuttini, Flavia M; Wang, Bing H; Jenkins, David G; Burke, Louise M

    PloS one, 05/2015, Letnik: 10, Številka: 5
    Journal Article

    Cycling is recognised as a sport in which there is a high incidence of poor bone health. Sweat calcium losses may contribute to this. To examine whether a calcium-rich pre-exercise meal attenuates exercise-induced perturbations of bone calcium homeostasis caused by maintenance of sweat calcium losses. Using a randomized, counterbalanced crossover design, 32 well-trained female cyclists completed two 90 min cycling trials separated by 1 day. Exercise trials were preceded 2 hours by either a calcium-rich (1352 ± 53 mg calcium) dairy based meal (CAL) or a control meal (CON; 46 ± 7 mg calcium). Blood was sampled pre-trial; pre-exercise; and immediately, 40 min, 100 min and 190 min post-exercise. Blood was analysed for ionized calcium and biomarkers of bone resorption (Cross Linked C-Telopeptide of Type I Collagen (CTX-I), Cross Linked C-Telopeptide of Type II Collagen (CTX-II), Parathyroid Hormone (PTH), and bone formation (Procollagen I N-Terminal Propeptide (PINP)) using the established enzyme-linked immunosorbent assay technique. PTH and CTX-I increased from pre-exercise to post-exercise in both conditions but was attenuated in CAL (p < 0.001). PTH was 1.55 1.20, 2.01 times lower in CAL immediately post-exercise and 1.45 1.12, 1.88 times lower at 40 min post-exercise. CTX-I was 1.40 1.15, 1.70 times lower in CAL at immediately post-exercise, 1.30 1.07, 1.57 times lower at 40 min post-exercise and 1.22 1.00, 1.48 times lower at 190 min post-exercise (p < 0.05). There was no significant interaction between pre-exercise meal condition and time point for CTX-II (p = 0.732) or PINP (p = 0.819). This study showed that a calcium-rich pre-exercise breakfast meal containing ~1350 mg of calcium consumed ~90 min before a prolonged and high intensity bout of stationary cycling attenuates the exercise induced rise in markers of bone resorption--PTH and CTX-I. Australian New Zealand Clinical Trials Registry ACTRN12614000675628.