A Short-Term Free-Fall Landing Enhances Bone Formation and Bone Material Properties

Abstract

To investigate the effects of a short-term free-fall landing course on local bone metabolism and biomaterial properties, 32 female Wistar rats (7 week old) were randomly assigned to three groups: L30 (n = 11), L10 (n = 11) and CON (n = 10). Animals in the L30 and L10 groups were subjected to 30 and 10 free-fall landings per day, respectively, from a height of 40 cm for five consecutive days. Animals' ulnae were studied using methods of dynamic histomorphometry, tissue geometry, biomaterial measurements and collagen fiber orientation (CFO) analysis. In dynamic histomorphometry analysis, periosteal as well as endosteal mineral apposition rates (MAR, μm/day) were significantly higher in L30 group than in the CON group (p < 0.05). In addition, the periosteal bone formation rate (BFR/BS, μm2/μm3/year) was significantly higher in the L10 and L30 groups (p < 0.05). The ulnae of the animals in the two landing groups were higher in post-yield energy without significant changes in CFO, tissue size or tissue weight measurements. In conclusion, a short-term free-fall landing training produced a slight, but significant, higher bone formation in the ulnae of young female rats. Enhanced tissue biomaterial properties did not accompany size-related changes, suggesting that bone adapting to mechanical loading begins with changes in tissue-level properties.

The Effects of Endurance Running Training on Young Adult Bone: Densitometry vs. Biomaterial Properties

“…After a short-term (5 days) freefall landing exercise, Wistar rats revealed an increased post-yield energy absorption in ulnae. 79 Such an enhanced absorption capability is more likely due to tissuelevel (e.g. bone matrix, collagen orientation etc) changes rather than structural adaptation.…”

“…As mentioned above, rats subjected to short-term freefall landing exercise (5 days, 10 or 30 times per day) from a height of 40cm also showed enhanced post-yield energy of ulnae. 79 In that study, authors tried to measure the CFO of cross-sectional ulnae. Unfortunately, no difference in CFO between exercise and control groups was found.…”