D-15 Free Communication/Slide - Exercise and Bone I: MAY 28, 2009 1:00 PM - 3:00 PM: ROOM: 619
PURPOSE: This study was designed to investigate the effect of an eight-week jump training program on markers of bone turnover. Based on the osteogenic index (OI), jumps were completed in one (J1×) or in two (J2×) daily sessions with total jumps per day being equal between groups. There was a 6hr recovery period between sessions (J2× only). We hypothesized J2× would elicit a greater increase in markers of bone formation and a greater decrease in markers of bone resorption than J1×.
METHODS: Seven males served as controls and participated in their normal strength training program. Fourteen males were divided two experimental groups, jumping once daily (J1×) or jumping twice daily (J2×). Jumping type exercises were performed on a plyo-press and started at 20 jumps/day, 3× per week and progressed to 60 jumps/day, 3× per week for the last 3 weeks. Blood samples were collected at baseline, week 4, and week 8 to determine serum concentrations of bone specific alkaline phosphate (BAP) and C-terminal telopeptides of type I collagen (CTx).
RESULTS: The OI for each session was different (P < 0.05) between the two groups (Baseline OI, J1×, 9.3 ± 1.3; J2×, 11.2 ± 1.8). There was a significant effect of time (P = 0.005) for changes in serum concentrations of BAP, 8-week values being significantly higher than baseline values (Change from baseline: J1×, 2.7 ± 1.4 ug/L; J2× 3.5 ± 1.3 ug/L). J2× had an overall mean change significantly different from zero. Change in serum concentration of CTx during the 8 weeks were (Control, -4.9 ± 3.3 ng/mL; J1×, 1.6 ± 3.1 ng/mL; and J2×, -3.8 ± 2.5 ng/mL).
CONCLUSIONS: The data demonstrate that the OI may be used to design programs to influence bone turnover. Additionally, compared to completing all jumps in one session, the use of recovery periods between jumping sessions on the same day may result in positive changes in bone turnover, indicative of an osteogenic effect.