Calcium-Rich Pre-Exercise Meal Attenuates Bone-Resorption Markers in Cyclists (RCT)
Protocol & Participants
n=32 well-trained female cyclists; randomised, counterbalanced crossover: two 90-min cycling trials separated by 1 day
2 hours before each trial: a calcium-rich dairy-based meal (CAL, 1352 ± 53 mg calcium) or a control meal (CON, 46 ± 7 mg calcium)
Blood pre-trial, pre-exercise, and immediately, 40, 100 and 190 min post-exercise: ionised calcium, bone-resorption markers (CTX-I, CTX-II), PTH, and the formation marker PINP (ELISA)
Key Results
PTH and CTX-I rose from pre- to post-exercise in BOTH conditions; the rise was attenuated in CAL
Authors' conclusion: a calcium-rich pre-exercise breakfast (~1350 mg calcium) eaten ~90 min before a prolonged, high-intensity stationary ride attenuates the exercise-induced rise in the bone-resorption markers PTH and CTX-I
Rationale (abstract): cycling has a high incidence of poor bone health; sweat calcium losses may contribute
Trial registration ACTRN12614000675628
Practical Application
In 32 well-trained female cyclists (randomised crossover), a dairy meal with ~1350 mg calcium eaten before a 90-min ride attenuated the exercise-induced rise in PTH and the bone-resorption marker CTX-I compared with a 46-mg control meal — a surrogate-marker result from single sessions, not a BMD or fracture outcome
Put the calcium in the pre-ride meal, not the post-ride one: dairy or fortified foods at roughly the studied amount (~1350 mg), 90 min to 2 h before a long or sweaty session (the abstract gives both timings)
Prioritise it where calcium loss is largest — heat, high sweat rates, high cycling volume — and in athletes carrying the non-impact-sport bone risk (REF-522). Not from this paper; the base's own practice
Female sample: the PTH/calcium mechanism is not sex-specific, but the transfer to men is untested here
Limitations
Surrogate markers (PTH, CTX-I), not direct BMD/fractures; a long-term bone effect is not proven by this trial
Female sample; transfer to men is mechanistically plausible but not tested here
Acute effect of single sessions; chronic benefit requires confirmation
n=32, well-trained cyclists
How this entry was checked and changed
Why this level
regraded 2026-09-27 from A: controlled crossover, n=32, surrogate markers
Content correction 2026-09-27
Added n=32, the control-meal dose (46 mg), timing (2 h before the trial; ~90 min before exercise in the conclusion), the sampling schedule and marker names; "β-CTX" -> CTX-I as in the abstract
"~1000-1350 mg" -> the studied dose was ~1350 mg; 1000 removed
Level A -> B+ (crossover n=32, surrogate markers); Sport line "cycling, strength" -> "cycling"