OBJECTIVETo explore the influence of different strength intermittent treadmill training of growth period rats on the bone metabolism, so as to provide the training intensity of teenagers to set theory support.

METHODSSelect 70 male four weeks Wistar rats according to body weight randomly divided into seven groups (n = 10): the control group and the exercise group. According to the VO2max the exercise group was divided into 6 groups: 65%, 70%, 75%, 80%, 85% and 90% group. Nine weeks treadmill training, training six days a week, each group of training three times, each time not less than 10min, the interval was 30 min. The last movement after 24 h, took the femur and blood to measured the bone mineral density (BMD), bone mass (BMC) and alkaline phosphatase (AKP), resist tartaric acid acidic phosphatase (Str-ACP).

RESULTS1. The femoral BMD (0.1393 +/- 0.0031), BMC (0.4525 +/- 0.0335) of 70% group were significantly higher than those in the control group (BMD: 0.1200 +/- 0.0095, BMC: 0.3238 +/- 0.0485) and the other sports group (65% BMD:0.1339 +/- 0.0062, BMC: 0.4058 +/- 0.0492, 75% BMD: 0.1296 +/- 0.0015, BMC: 0.3869 +/- 0.0254, 80% BMD: 0.1223 +/- 0.0082, BMC: 0.3454 +/- 0.0483, 85% BMD: 0.1250 +/- 0.0044, BMC: 0.3731 +/- 0.0381, 90% BMD: 0.1171 +/- 0.0047, BMC: 0.3051 +/- 0.0286) (P < 0.05), the femoral BMD, BMC of 90% group were lower than those of the control group, the other in the exercise group were higher than those in the control group; 2. Serum AKP in the exercise group were significantly higher than those in the control group, the group of 65% (41.015 +/- 2.114), 70% (46.035 +/- 2.611), 75% (43.834 +/- 3.155), and 80% (38.043 +/- 4.073) were very significantly higher than those in the control group (26.875 +/- 1.188) (P < 0.01); 70% group and 75% group were significantly higher than those in the 80% group , 85% group and 90% group, while 70% group serum AKP level were significantly higher than those in 65% group (P < 0.05), it showed that 70% of the VO2 max training intensity of osteoblasts was most active. The serum Str-ACP of exercise group were significantly higher than those in the control group, along with the increase of the training intensity, serum Str-ACP level was rising and the group of 80% (22.430 +/- 1.591), 85% (23.990 +/- 1.870), and 90% (28.009 +/- 1.839) serum of Str-ACP were significantly higher than those in the group of 65% (18.503 +/- 2.429), 70% (16.447 +/- 2.120) and 75%(17.769 +/- 1.642) ( P < 0.05), the group of 90% serum Str-ACP were significantly higher than those in the group of 80% and 85% (P < 0.05).

CONCLUSIONThe training of 70% of the VO2max, moderate intensity intermittent running, make the growth period rat bone mass and bone mineral density to increase obviously.