Changes of bone metabolism markers following additional isokinetic and isotonic training and its subsequent cessation in advanced level adolescent weightlifters

Background: Physically active people present overall accelerated bone turnover. However, less is known about the effects of different types of resistance training on bone metabolism markers among adolescent weightlifters. Objective: The purpose of this study was to investigate the effects of isokinetic training versus isotonic training of rotator cuff muscles and one month of cessation of training on blood bone metabolism markers among adolescent advanced level weightlifters. Methods: Sixteen adolescent male weightlifters (age 14.88 ± 1.31 years) who represented their state in Malaysia were weight-matched and randomly assigned into two training groups: isokinetic training (FIT, n = 7) and isotonic training (TON, n = 9) groups. The experiment was conducted during the preparatory phase of the training cycle for a total of 24 sessions with three sessions per week for eight weeks using dynamometer or dumbbells. Blood samples were collected before the commencement of training, after training and one month following the cessation of training and analyzed for determining blood metabolism markers of serum osteocalcin, serum C-telopeptide of type 1 collagen (CTX-1), and serum total calcium. Results: Total calcium concentrations were not different between groups at any time, as indicated by a non-significant main effect of time (F = 1.89, p = .166) and no condition × time interaction effect (F = 0.64, p = .533). Serum osteocalcin concentrations were not different between groups at any time, as indicated by a non-significant main effect of time (F = 2.10, p = .162) and no condition × time interaction effect (F = 0.024, p = .912). Serum CTX-1 concentrations were not different between groups at any time, as indicated by a non-significant main effect of time (F = 3.12, p = .059) and no condition × time interaction effect (F = 1.59, p = .221). Conclusions: No significant changes were observed in serum total calcium, osteocalcin and CTX-1 following either eight weeks of isokinetic or isotonic additional training among advanced level of adolescent weightlifters.