Objective: Biochemical markers of bone turnover are commonly used predictors of bone metabolism and for diagnosis of osteoporosis and treatment evaluation. Both resistance and endurance training has been shown to influence bone metabolism markers. However, the timeline of this response, and possible differences between exercises have not yet been appropriately investigated. It also remains uncertain if such alterations in serum levels differ between genders.
Methods: Thirty-six healthy young men (24 2.1 years) and women (24.2 2.3 years) underwent heavy resistance leg press training (4 x 8-10 repetitions, 80% of 1RM) and high-intensity interval treadmill running (4 x 4 min, 90% HRmax). Blood samples were taken before and 0-5 min, 3 h and 24 h after training, and analyzed by immunoassays to assess serum bone biochemical markers osteocalcin (OC), procollagen type 1 N propeptide (P1NP) and carboxy-terminal collagen crosslinks (CTX). Strength and aerobic capacity (1RM, RFD and V ̇O2max) were assessed before training to ensure accurate exercise intensity.
Results: Heavy resistance training decreased serum levels of OC and CTX from baseline until 3 h post-training (p < 0.05 for both), before returning to baseline levels after 24 h. No change in P1NP occurred after resistance training. Endurance training increased serum P1NP, OC and CTX at 0-5 min after training, before decreasing 3 h post-training (p < 0.05 for all) and returning to baseline after 24 h. All serum bone markers were different between resistance and endurance training 0-5 minutes after training (p < 0.001). No difference in change of serum levels between men and women were observed.
Conclusion: Our study revealed that heavy resistance training and high-intensity interval training altered bone turnover immediately after training, before returning to baseline. This indicates that bone biochemical markers P1NP, OC and CTX may be appropriate to monitor for bone metabolism assessment during resistance and endurance training interventions.