Parathyroid Hormone (PTH) Secretion is Controlled by both Ionised Calcium and Phosphate During Exercise and Recovery.

The Effect of Postexercise Carbohydrate and Protein Ingestion on Bone Metabolism

“…Indeed it should be noted that in a normal, healthy basic multicellular unit, the suppression of bone resorption may not always be desired, if the function of bone resorption is to breakdown and remove damaged bone at areas of microdamage accumulation to allow the area to be repaired and strengthened. The responses of Ca 2+ and PO to exercise are in line with previous research (37) and the responses are only significantly different between trials at 1 h post-exercise; Ca 2+ concentrations were lower in the PLA trial compared to the IF trial, suggesting that IF augments the recovery of Ca 2+ to baseline concentrations, and PO 4 is lower in the IF trial compared to the DF trial. Transient peaks in PTH concentrations, as shown in the present study, are shown to be anabolic for bone (10) and Townsend et al (37) showed that PTH secretion during exercise and recovery is controlled by both Ca 2+ and PO 4 , therefore these metabolites are likely to be mediating any anabolic effect of increased PTH concentrations.…”

“…Considering that the action of increased PTH secretion is to increase calcium through mobilisation of the bone reservoir via activation of bone resorption (and also by increasing renal tubular reabsorption and intestinal calcium absorption) (24,35,40), this suggests that changes in PTH and calcium metabolism are unlikely to mediate the acute suppression in bone resorption seen with postexercise CHO+PRO feeding. However, ACa has been shown to be unsuitable when investigating the rapid response of calcium metabolism to exercise (37), which may also be true when investigating CHO+PRO ingestion around exercise. Although Ca 2+ (non-protein bound calcium) decreased at the end of exercise, because albumin concentrations increased, ACa was normalised and remained fairly unchanged throughout exercise.…”