Resistance and interval running exercise exert differential short-term post-exercise bone metabolic marker responses in postmenopausal

PURPOSE: This study examined the effects of resistance exercise versus interval running on post-exercise concentrations of bone metabolic markers in postmenopausal females. METHODS: Thirteen physically active postmenopausal women (51 ± 3 years) completed this crossover trial consisting of two exercise modalities: an interval running protocol (8 × 3 min at 85% maximal aerobic speed) and an eccentric-based resistance protocol (10 × 10 parallel back squats at 60% 1RM). Blood samples were obtained at baseline and 24 h post-exercise. Dickkopf-related protein 1 (DKK-1), fibroblast growth factor 23 (FGF-23), osteocalcin, osteoprotegerin (OPG), parathyroid hormone (PTH), and sclerostin were analysed in serum. A mixed linear model was used to examine the main effects of exercise and time, and the Exercise × Time interaction. RESULTS: Significant Exercise × Time interactions were shown for osteocalcin (p = 0.015), OPG (p = 0.021), and sclerostin (p = 0.002), with higher concentrations 24 h after resistance exercise than following endurance exercise. A main effect of Exercise was detected for FGF-23 (p = 0.048), showing higher values in resistance exercise. CONCLUSION: Resistance and interval running exercise elicited distinct short-term bone metabolic responses in postmenopausal women. Twenty-four hours after exercise, resistance loading resulted in higher concentrations of total osteocalcin, sclerostin, and OPG, but not DKK-1, FGF-23 or PTH, compared with interval running. These findings show some upregulation of bone metabolic signalling after resistance exercise compared to interval running, although interpretation must remain cautious given that total osteocalcin and OPG do not directly reflect net bone formation or resorption.