Effects of a 16-week progressive high-intensity strength training (HIST) on indexes of bone turnover in men over 65 years: A randomized controlled study

The aim of the present study was to evaluate the effects of a 16-week progressive high-intensity strength training (HIST) program on peripheral markers of bone turnover (bone Gla protein, BGP; bone alkaline phosphatase, B-AP; N-terminal propeptide of type I procollagen, PINP; C-terminal cross-linked telopeptide of type I collagen, ICTP) in healthy, elderly men over 65 yr of age. Thirty healthy men (aged 65-81 yr), performing light to moderate daily physical activity, were randomly divided into two groups. Group 1 (no.=16) followed a supervised 16-week progressive HIST program, while subjects of group 2 (no.=14), used as controls, were requested to maintain their habitual level of physical activity for 16 weeks. HIST program consisted of 6 different sets of exercise (2 involving the major muscle groups of the lower limb and 4 involving those of the upper limb). Three sessions/week, during which 10 repetitions of each exercise set were completed, were performed. Lower limb exercises shifted from 50 to 80% of the one maximal repetition (1 MR) during the first month of the protocol and were thereafter maintained at an intensity of 80% 1 MR throughout the training. Upper limb exercises shifted from 40 to 65% of 1 MR with a similar pattern. All sessions were preceded by 15 min of cycloergometer exercise at 50% of maximal oxygen uptake and by a warm-up of 15 repetitions at 20% of 1 MR of each exercise set. The HIST program did not significantly change BGP (mean +/- SE, before: 15.6 +/-1.2 mug/l vs after: 16.0 +/-1.2 mug/l, NS) and PINP levels (before: 44.6 +/-6.7 mug/l vs after: 43.1 +/-6.0 mug/l, NS). On the contrary, serum B-AP significantly increased (before: 50.2 +/-6.1 IU/l vs after: 62.3 +/-7.0 IU/l, p <0.001) and serum ICTP slightly reduced (before: 4.0 +/-0.3 mug/l vs after: 3.8 +/-0.3 mug/l, p <0.05). When bone turnover was expressed as the ratio between bone formation to bone resorption (B-AP/ICTP ratio), a significant improvement in this ratio was found in all subjects of group 1 (before: 12.9 +/-1.3 IU/mug vs after: 17.3 +/-1.5 IU/mug, p <0.0001), while no significant changes were observed in Group 2. No significant changes of IGF-I levels were observed after the HIST program (before: 94.9 +/-9.4 mug/l vs after: 89.9 +/-9.7 mug/l). No significant changes of BGP, PINP, B-AP, ICTP, B-AP-ICTP ratio and IGF-I levels were observed in controls (group 2) during the 16 weeks of observation. Although the positive effects of a progressive HIST program on B-AP levels and B-AP-ICTP ratio seem promising, the support of bone mass measurement and the determination of other bone markers are requested to better identify exercise protocol (duration, intensity) for elderly people. (C) 2001, Editrice Kurtis.