Relationships between work loads and cardiovascular responses in Master's double two step test, in treadmill test and in bicycle ergometer test was studied. Comparison were made among different exercise methods when the peak heart rates were controlled to be the same. First, double two step test was done and the peak heart rates were evaluated. Next treadmill test was done. The gradient was fixed to 10 degrees, and the speed was increased gradually by automatically controlled method until the peak heart rates reached to the same level as that in double two step test. Thirdly, bicycle ergometer test was performed. The resistance was increased similarly unitl the peak heart rates got to the same as that in double two step test.
The work loads of treadmill test, in which the peak heart rates were the same as that in double two step test, was the gradient of 10 degrees and the speed of 67.7±5.0 (mean±standard error of the mean) meter per second. The same peak heart rates were obtained in bicycle ergometer test by the resistance of 541.8±36.3 kilopond meters per minute (90.3±6.0 watt). The cardiovascular loads except heart rates, systolic and diastolic blood pressure, pressure rate product (PRP) and Katz' cardiac effort index, were all higher in bicycle ergometer than those in the other two tests. O₂ consumption (VO₂) was higher in treadmill test than those in the others. All the parameters except PRP/VO₂ had no significant differences between bicycle ergometer test and the other two tests, treadmill test and double two step test.

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The cardiac function in patients with acute myocardial infarction (aMI) was succesively examined by graded exercise testing after discharge. The subjects were 51 male patients with average age of 58. At discharge and 6 months, 12 months and 2-3 years after the attack, intermittent multiple load tests (five minutes each at 25W, 50W, 75W and 100W) were performed using a bicycle ergometer in the upright position. The criteria for discontinuation of the tests included subjective symptoms such as appearance of chest pain, dyspnea and fatigue and objective symptoms such as ST changes of more than 2mm compared to the level at rest and appearance of severe arhythmias on the electrocardiographic recordings.
Exercise tests were carried out in 51, 36, 38 and 25 cases at discharge and 6 months, 12 months and 2-3 years after the attack, respectively. The cases in which loading was discontinued due to cardiac complications such as reinfarction, angina pectoris, heart failure and arhythmia accounted for 16%, 19% and 17% at 6 months, 12 months and 2-3 years after the attack, respectively.
An increase was observed in physical work capacity (PWC) 6 months after the attack, which was maintained thereafter until 2-3 years after the attack. The cardiac function assessed by PWC, physical fitness index (PFI), changes in ECG and subjective symptoms showed improvement in 53%, 62% and 70% of the patients 6 months, 12 months and 2-3 years after the attack, respectively. Thus, a remarkable improvement occurred within 6 months, and gradual improvement continued until 2-3 years after the attack.
PWC at discharge was higher for the patients with ages younger than 59 years, limited infarction, initial attack and without heart failure or arhythmia in the acute stage, in whom more increase in PWC was recorded after discharge. Among these patients, there were few in whom loading was obliged to be discontinued due to cardiac complications.
With 50W load, a significant increase was seen in PFI, respiratory efficiency, O₂-consumption and O₂-pulse at every check point after discharge comparing to the values at discharge, while a decrease was observed in heart rate. However O₂-debt and cardiac output was slightly improved.
One year after the attack of aMI, 50% of the patients could return to full time job, 26% to part time and 24% could not return to work. The greater was the PWC of the patients at discharge, the higher was the rate of the return to work.
From these data, it was concluded that the patients with lesser clinical findings in the acute stage and greater PWC at discharge could rehabilitate in earlier period after the attack.

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