Bone density benefits with periodic fluid redistribution during diminished muscular activity in humans.

Objective: Bone loss is an established reaction to diminished muscular activity (Hypokinesia; HK). It has been assumed that periodic fluid redistribution (PFR) could contribute to vascular volume. The fluid volume expansion would then increase tissue perfusion. We hypothesized that chronic PFR could contribute to or increase bone density during HK. Therefore we investigated the potential benefits of bone density with chronic PFR during HK. Methods: Studies were conducted on 40 male volunteers. They were equally divided into four groups: active control subjects (ACS), hypokinetic subjects (HKS), periodic fluid redistribution control subjects (PFRCS) and periodic fluid redistribution hypokinetic subjects (PFRHS). The density of lumbar vertebrae (L1-L4), ulna and radius, tarsal and metatarsal, tibia and fibula were measured during pre-experimental period of 390 days and experimental period of 360 days. Results: Density of lumbar vertebrae (L1-L4), ulna and radius, tarsal and metatarsal, tibia and fibula increased (p<0.05) in the PFRHS group compared to the HKS group. Density of lumbar vertebrae (L1-L4), ulna and radius, tarsal and metatarsal, tibia and fibula decreased (p<0.05) in the HKS group compared to their preexperimental levels and the values in the other groups. In the PFRCS group lumbar vertebrae (L1-L4), ulna and radius, tarsal and metatarsal, tibia and fibula density were improve much less than in the PFRHS group. Bone density was not affected in the ACS group compared to their pre-experimental levels. Conclusion: The current study shows that bone density increases with chronic PFR suggesting potential benefits of bone density with chronic PFR during diminished muscular activity.