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As the number of patients with heart disease increases in Korea, interest in cardiac rehabilitation is increasing. The cardiac rehabilitation exercise requires a certain amount of exercise according to the target heart rate, and monitoring of the medical personnel is required because the pattern of increasing and decreasing heart rate is different according to the person. in this regard, research on controlling the heart rate using a treadmill or ergometer is underway in foreign countries, but there are few studies in Korea. In addition, it is difficult to model and control the heart rate of human body because it has high nonlinearity. In this paper, to overcome this problem, we approximated a 2nd order linear system, modeled it and simulated using a robust controller, SMC. In the future, the experiment will be conducted for the normal people.

Subjects in Phase 1 of this experiment were (a) instructed to try to either increase or decrease their heart rate, (b) with or without the use of biofeedback, and (c) with or without the promise of money for successful performance, whereas no-treatment subjects were given no instructions, no biofeedback, and no promise of reward. Results indicated that (a) when simply instructed to do so, subjects could increase but not decrease their heart rates relative to no treatment controls, (b) the promise of money for good performance aided subjects in increasing but not decreasing heart rate, and (c) biofeedback did not aid subjects in either increasing or decreasing heart rate. Various cognitive strategies employed by subjects in controlling their heart rates are discussed. In Phase 2, subjects in a stress condition were told that they would receive a series of painful electric shocks, whereas subjects in a no stress condition were not told about shocks. All subjects were instructed to try to decrease their heart rates during the “shock” period. Heart rate and self report data revealed that (a) the manipulation was successful in increasing stress, and (b) previous training in decreasing heart rate, with or without biofeedback, did not aid subjects in decreasing their heart rates in the face of the stress.

Four patients who had suffered a myocardial infarction were given biofeedback training in order to assess (1) the possibility of increasing heart rate variability with the help of a feedback; (2) the possible cardiac consequences, from the clinical viewpoint, of biofeedback treatment. A biofeedback procedure alternately increasing and decreasing heart rate under instruction and feedback-plus-instruction conditions, was used. Evaluation of clinical parameters was effected by Holter dynamic ECG and by means of a graded submaximal effort test on the cycloergometer. The results show: (1) poor capacity to increase heart rate variability, but a tendency towards small unidirectional modifications; (2) no significant clinical modification except in isolated parameters. Further study is necessary to assess the usefulness of biofeedback training in the rehabilitation treatment of post-infarction patients. The datum, confirmed elsewhere, concerning apparent cardiovascular ‘rigidity’ in such patients, is interesting but requires clarification.

The effects of heart rate feedback delay upon bidirectional heart rate control were determined by comparing four groups of 10 subjects who received either: a) immediate feedback, or b) feedback that was delayed by 1.4 sec, 5 sec, or 14 sec. All subjects received 3 sessions of training which included 3 within-session phases, i.e. 2 (pre and post-feedback) Instructional Control phases during which subjects were instructed to speed or slow heart rate without the aid of feedback, and a Feedback phase during which bidirectional heart rate control was assisted by analogue heart rate feedback. Heart rate, chin EMG, and respiration rate were recorded during all phases. The results indicated that the magnitude of heart rate increases and decreases was systematically influenced by differing amounts of feedback delay. For increasing and decreasing heart rate, the group receiving immediate feedback showed superior heart rate control in comparison to groups which received feedback that was delayed by 14 sec. The strongest effects of feedback delay were evident during Feedback and the final Instructional Control phase. Only the group receiving immediate feedback improved HR control during Feedback and post-feedback Instructional Control phases. These findings were discussed in terms of a motor skills learning model for learned HR control. It was concluded that while many of the same parameters influence HR and motoric behavior, the two responses should not be regarded as equivalent.

The effect of respiratory constraint on heart rate control was assessed in a biofeedback situation with feedback consisting of changes in both illumination level and intensity of a prerecorded baby's cry. Subjects were reinforced for alternately increasing and decreasing heart rate on each of seven days during which respiration was unconstrained (Phase 1). This phase was followed by eight days when respiration was constrained during training sessions with a control respirator (Phase 2). Seven additional days of training followed in the unconstrained situation (Phase 3). Results indicate that the control of heart rate in biofeedback situations is very closely related to respiratory and other somatic activity. The implication of these findings for the field of visceral control is discussed.

Fifty-six adult males who were hospitalized with anxiety related problems were randomly assigned to the conditions formed by a 2 (instructions to increase heart rate, instructions to decrease heart rate) × 3 (true biofeedback, placebo biofeedback, no biofeedback) factorial plus 1 (no-treatment control) design. Subjects were seen for 4 heart rate training/recording sessions and 1 subsequent transfer-test session. Results indicated that: a) neither instructions alone nor the combinations of instructions and true or placebo biofeedback were more effective than simply sitting quietly (adaptation) for decreasing heart rate, b) instructions plus true biofeedback was more effective than instructions alone or instructions plus placebo biofeedback for increasing heart rate, c) multiple sessions of training did not enhance the level of control achieved early in the first session, d) the control achieved with biofeedback did not transfer to a subsequent no-biofeedback situation, and e) biofeedback training did not influence subjects' subjective anxiety levels.