Short-term jump activity on bone metabolism in female college-aged nonathletes

Abstract

There have been few studies examining the short-term effect of high-impact activities on bone metabolism measured by bone serum marker concentrations. The purpose of this study was to examine the effect of short-term high-impact jump activity on bone turnover in female college-aged non-athletes. Twenty six healthy females were randomly assigned to a control or jump group. The subjects jumped 5 days per week for 2 weeks. The participants completed 10 jumps per session. A general health questionnaire and a bone-specific physical activity assessment instrument (BPAQ) were completed. BPAQ scores were calculated based on the past history of exercise. Blood draws were taken in both groups before and after the two-week experimental period. The vertical ground reaction force (VGRF) of all jumps and jump height were measured for each subject daily and the osteogenic index (OI) was measured. Concentrations of serum osteocalcin (OC), Bone Specific Alkaline Phosphatase (BAP), C-Terminal Telopeptides of Type I Collagen (CTX) and plasma Tartrate-Resistant Acid Phosphatase (TRAP5b) were assessed pre and post jump protocol to measure bone formation and resoprtion respectively. A significant interaction (time x group) was found in TRAP5b, and BAP values (p < 0.05). There was a significant decrease in CTX and BAP values in the jump group (p < 0.05) after the two week jump protocol. No significant interactions or changes were observed in OC values for either the jump or the control group. Two weeks of jump activity consisting of 10 jumps/day for 5 days/week with a weekly osteogenic index of 52.6 significantly decreased markers of bone resorption (TRAP5b and CTX) and bone formation (BAP) in young female non-athletes.

Keywords: Jump exercise; bone serum markers; randomized controlled study; vertical ground reaction force.

Figure 1.

Images of the plyometric jump used in the training protocol. Participants began on a 40cm box, dropped to the forceplate and jumped as high as possible (using the Vertec measuring device) and landing on the forceplate. Representative force plate tracing illustrating the magnitudes of the two landings.

Figure 2.

Pre-test and Post-test bone serum marker concentration in jump group and control group. Two-way repeated measures ANOVA was computed to determine a (time x group) interaction for each marker. Significance does not indicate an increase or decrease in the magnitude of the markers just that control and jump groups responded differently. Unpaired t-tests were used to detect differences in the change between the differences post-pre between the control and jump groups a similar analysis to the interaction term. A. Serum Trap5b levels (U/I) B. Serum CTX levels (ng·mL-1) C. Serum Osteocalcin levels (ng·mL-1) D. Serum BAP levels (U/L) Means ± SEM * Significant interaction (time x group) p < 0.05 # Significant difference (post - pre) between groups.

Figure 3.

Differences (Post-Pre) in Bone Serum Marker Concentrations within the jump group and control group. Paired t-test were used to determine changes from pre to post within groups. A. Serum Trap5b levels (U/I) B. Serum CTX levels (ng·mL-1) C. Serum Osteocalcin levels (ng·mL-1) D. Serum BAP levels (U/L) Means ± SEM * Significant difference (p < 0.05).