運動訓練에 對한 心肺機能의 適應에 關한 硏究

Abstract

[한글]

[영문]

As pointed out by many previous investigators, the cardio-pulmonary system of well-trained athnletes is so adapted that they can perform a given physical exercise more efficiently as compared to non-trained persons. However, the time course of the development of these cardio-pulmonary adaptations has not been

extensively studied in the Past. Although the development of these training effects is undoubtedly related to the magnitude of an exercise load which is repeatedly given, it would be Practical if one could maintain a good physical fitness with a minimal daily exercise. Hence, the present investigation was undertaken to study the time course of the development of cardio-pulmonary adaptations while a group of non-athletes was subjected to a daily 6 to 10 minutes running exercise for a period of 4 weeks.

Six healthy male medical students (22 to 24 years old) were randomly selected as experimental subjects, and were equally divided into two groups (A and B). Both groups ware subjected to the same daily running exercise (approximately 1,000 kg·m) 6 days a week for 4 weeks, hut the rate of exercise was suck that the group A ran on treadmill with 8.6% grade for 10 min daily at a speed of 127 m/min while the group B ran for 6 min at a speed of 200 m/min. In order to assess the effects of these physical trainings on the cardio-pulmonary system, the minute volume, the

0^^2 consumption, the CO^^2 output and the Heart rate were determined weekly while the subject was engaged in a given running exorcise on treadmill (8.6% grade and 127 m/min) for a period of 5 min. In addition, the arterial blood pressure, the

cardiac output, the acid-base state of arterial blood and the gas composition of arterial blood were also determined every otter week in 4 subjects (2 from each group) while they were engaged in exercise on a bicycle ergometer at a rate of approximately 900 kg·m/min until exhaustion. The maximal work capacity was also

determined by asking the subject to engage in exercise on treadmill and ergometer until exhaustion. Fer the measurement of minute volume, the expired gas was collected in a Douglas bag. The O^^2 consumption and the CO^^2output were subsequently computed by analyzing the expired gas with a Scholander micro gas

analyzer. The heart rate was calculated from the R·R interval of ECG tracings recorded by an Offner RS Dynograph. A 19 gauge Cournand needle was inserted into a brachial artery, through which arterial blood samples were taken. A Statham P^^23 AA pressure transducer and a PR-7 Research Recorder were used for recording instantaneous arterial pressure. The cardiac output was measured by indicator (Cardiogreen) dilution method.

The results may be summarized as fellows:

(1) The maximal running time on treadmill increased linearly during the 4 week training period at the end of which it increased by 2.8 to 4.6 times. In general, an increase in the maximal running time was greater when the speed was fined at a

level at which the subject was trained. The maximal exercise time on bicycle ergometer a1so increased linearly during the training period.

(2) In carrying out a given running exorcise on treadmill (8.6%grade, 127 m/min), the following changes in cardio-pulmonary functions were observed during the training period:

(a) The minute volume as well as the 0^^2 consumption during steady state exercise tended to decrease progressively an? showed significant reductions after 3 weeks of training.

(b) The CO^^2 production during steady state exercise showed a significant reduction within 1 week of training.

(c) The heart rate during steady state exercise tended to decrease progressively and showed a significant reduction after 2 weeks of training. The reduction 7f heart rate following a given exercise tended to become faster by training and showed a significant change after 3 weeks. Although the resting Heart rate also tended to decrease by training, no significant change was observed.

(3) In carrying out a given exercise (900 kg·m/min) on a bicycle ergometer, the following changes in cardio-vascular functions were observed during the training period:

(a) The systolic blood pressure during steady state exercise was not affected while the diastolic blood pressure was significantly lowered after 4 weeks of training. The resting diastolic pressure was also significantly lowered by the end

of 4 weeks.

(b) The cardiac output and the stroke volume during steady state exercise increased maximally within 2 weeks of training. However, the resting cardiac output was net altered while the resting stroke volume tended to increase somewhat by training.

(c) The total peripheral resistance during steady state exercise was greatly lowered within 2 weeks of training. T7e mean circulation time during exercise was also considerably shortened while the left heart work output during exercise increased significantly within 2 weeks. However, these functions at rest were not altered by training.

(d) Although both pH, P^^co2 and (HCO^^3 ) of arterial plasma decreased during exercise, the magnitude of reductions became less by training. On the other hand, the O^^2 content of arterial blood decreased during exercise before training while it tended to increase slightly after train-ing. There was no significant alteration in these values at rest.

These results indicate that cardio-pulmonary adaptations to physical training can be acquired by subjecting non-athletes to brief daily exercise routine for certain period of time. Although the time of appearance of various adaptive phenomena is

not identical, it may be stated that one has to engage in daily exorcise routine for at least 2 week? for the development of significant adaptive changes.