The impact of physical exercise on calcium balance in healthy subjects during prolonged hypokinesia.

Objective: To determine whether during hypokinesia (diminished movement) periodic physical exercise affects calcium (Ca(2+)) balance and Ca(2+) loss.

Methods: Studies were conducted on 30 physically healthy male volunteers during the preexperimental period of 30 days and the experimental period of 364 days. They were equally divided into three groups: active control subjects (ACS), hypokinetic subjects (HKS), and periodic training subjects (PTS). The ACS group ran an average distance of 9.3+/-1.2 km/d; the HKS group walked an average distance of 1.3+/-0.2 km/d; and PTS group walked and ran average distances of 1.3+/-0.2 km/d and 9.2+/-1.2 km/d for 5 and 2 days per week, respectively.

Results: Serum Ca(2+) level, fecal and urine Ca(2+) loss, and Ca(2+) imbalance increased (P<0.05) in the PTS and HKS groups compared with their preexperimental levels and the values in their respective ACS group. The serum Ca(2+) concentration, urine and fecal Ca(2+) loss, and Ca(2+) imbalance increased more (P<0.05) in the PTS group than in the HKS group.

Conclusion: During hypokinesia, Ca(2+) imbalance is more evident with than without physical exercise and Ca(2+) loss is exacerbated more with higher than lower Ca(2+) imbalance.