Author(s): RODRÍGUEZ-REDONDO, B., GUISADO-CUADRADO, I., BELL, M., ROMERO-PARRA, N., TORRES-SANTIAGO, M., ELLIOTT-SALE, K.J., SALE, C., KLENTROU, P., PEINADO, A.B., Institution: UNIVERSIDAD POLITÉCNICA DE MADRID, Country: SPAIN, Abstract-ID: 264

INTRODUCTION:
Physical exercise is a powerful strategy to improve bone health as mechanical loading stimulates bone formation (1,2). Low sex hormones accelerate bone loss and sensitivity to loading declines (3). Different loading patterns generate distinct osteogenic responses (4), and menopause-related hormonal changes such as, reduced oestrogen mechanosensitivity (3) and elevated FSH (5), which may alter bone remodelling and the metabolic impact of endurance versus resistance exercise. Therefore, this study examined the effects of resistance exercise versus interval running on post-exercise concentrations of bone-derived proteins in postmenopausal females.
METHODS:
Thirteen physically active postmenopausal women (51±3 years) participated in a randomized, 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.
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 (osteocalcin: 7170.1±2,730.8 pg/mL; OPG: 437.2±96.7 pg/mL; sclerostin: 558.2±192.3 pg/mL) than following interval running (osteocalcin: 3478.1±1833.8 pg/mL; OPG: 390.92±122.5 pg/mL; sclerostin: 475.7±99 pg/mL). A main effect of Exercise was detected for FGF-23 (p=0.048), showing higher values in resistance exercise (22.6 ± 9 pg/mL) than in interval running (18.5±8.2 pg/mL). No significant main effects or interactions were shown for DKK-1 nor for PTH.
CONCLUSION:
Resistance and interval running 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 compared with interval running, consistent with the greater mechanical strain imposed by resistance work. These findings show an 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 and may reflect short-term regulation adjustments during early recovery.

References
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