1983 Volume 27 Issue 4 Pages 301-308
The maximum oxygen intake (V^^.O_2 max) and endurance running time (1500m run) of the mentally retardeds were compared with those of nonretarded children. The subjects were 21 mentally retarded boys, aged 12 and 13 years, ranging in IQ scored from 25 to 55, and 27 nonretarded boys with comparative age range. The V^^.O2 max was measured by the bicycle ergometer method. Among the retarded subjects, 14 boys could not reach the heart rate level of 180 beats/min (Retarded B), though the other seven retardeds (Retarded A) and all the nonretardeds were able to reach this level. The maximum heart rate level of the nonretardeds, the Retarded A and the Retarded B were 191, 187 and 151 beats/min, respectively. The Retarded A showed significantly lower working capacities than the nonretarded group. Their V^^.O_2 max/wt was 40.1 ml/min/kg, which was 83.1% of that for the nonretarded. The Retarded B showed much smaller endurance capacity. They had a mean peak V^^.O_2/wt of 29.9ml/min/kg, which was 60.8% of that for the nonretarded. The 1500m run performance of the nonretardeds, the Retarded A and the Retarded B were 370, 477 and 842 sec, respectively. One of the characteristics specific to the retardeds' endurance was observed in V^^.O_2max/wt-1500m run record relationship. The performance level of 1500m run in the retarded group was still lower when the comparison was made in relation to their V^^.O_2max/wt (or Peak V^^.O_2/wt) levels; i.e., the ratio of 1500m record to V^^.O_2max/wt (or Peak V^^.O_2/wt) of the Retarded A and the Retarded B were 11.7 and 28.2, respectively, in compatrison to 7.52 for the nonretarded. The subjects of Retarded B participated in 10 minutes endurance training three times a week. During the three months of training, their maximum heart rate increased significantly from a mean of 151 beats/min to 165 beats/min, and five subjects reached the heart rate level of 180 beats/min. With this change, endurance capacity also improved, the Peak V^^.O_2 and 1500m record after training reached 33.4ml/min/kg and 612 sec, respectively. The ratio of 1500m run to Peak V^^.O_2/wt, therefore, decreased to 18.2. Regression equations of 1500m run record to Peak V^^.O_2/wt were. 1500m record=1586.03-24.85 (Peak V^^.O_2/wt) for pre-training, 1500m record=1167.76-16.64 (Peak V^^.O_2/wt) for post-training. The results indicated that, within this materials and training conditions, relatively greater improvement was shown in endurance time rather than that in Peak V^^.O_2. This tendency was especially conspicuous in the subjects with smaller endurance capacity at the initial level. The characteristics of these results were discussed in relation to psychological tolerance to the exercise.