[Preventive effects of exercise training on bone loss during 21 d -6 degrees head down bed-rest].

Objective: To observe the protective effects of exercise training during 21 d -6 degrees head down bed rest (HDBR) on bone loss.

Method: Ten healthy young men were randomly divided into HDBR group and HD-BR exercise group, with 5 in each group. Both groups were exposed to -6 degrees head down bed rest for 21 d.