ABSTRACT
Objective The aim of the study is to investigate whether the progressive incremental exercise can induce the change in bone maximum force.Methods One hundred and seventy healthy SD rats,aged 3 months,were used as samples after adaptive exercise for one week,and then they were divided to a basic control group(C_0),8 control groups and 8 exercise groups according to the training duration(2W,4W,6W,8W,9W,11W,13W and 15W).Based on Bedford and our pre-study.the longest training duration of the rats was 15 weeks.The maximum force(F) of femoral bone and the 2nd lumbar vertebrae(L_2)were tested by three-point bending test and compressive test separately.Results It was shown that there was no pronounced difference in F of femoral bone between con trol groups and exercise groups.But significant differences in F of L_2 were found between the control groups and exercise groups(P<0.001).Conclusions Changes in different degree were found in the F of femoral bone and L_2 during the process of growth.The differential effects of incremental exercise on F were caused by the difference in training intensities and in the bone types.