This is a quasi-experimental research study to test the effects of respiratory muscle training.
The purposes of the study were 1) to deter-mine the effects of respiratory muscle training in patients with COPD, 2) to determine the duration of training necessary for effective respiratory muscle strengthening and 3) to identify the differences´ between two different training methods (strength training and the combination of strength and endurance training).
Sixteen participants were selected according to the criteria from the outpatient clinics of two university hospitals from September 1, 1985 to March 14, 1987, but only ten participants completed the training.
These ten were randomly assigned to two groups and received respiratory muscle training for 8 weeks. Participants. in Group I received strength training only, and the participants in Group II received strength training and endurance training by one of two methods; 12 minutes of walking or 20 minutes of treadmill training.
To obtain the baseline data of the effects of training, maximal inspiratory pressure(PImax) and maximal voluntary ventilation (MVV) of ,each patient were measured three times with
intervals of 4 to 7 days prior to the training, while sustainable inspiratory pressure(SIP), 12-minute walking distance, bronchitis-emphysema symptoms checklist (BESC) and activities of daily living(ADL) were measured only once prior to the training. PImax, SIP and MVV were measured once a week for 8 weeks during the training period. Twelve-minute walking distance, BESC, ADL were measured once at the completion of the training.
The effects of strength training were measured by PImax. The effects of endurance training were measured by SIP and MVV. And the combined effects were measured by the distance walked in 12=minutes, BESC, and ADL.
Wilcoxon signed-rank test, Friedman two-way analysis of variance, and Mann-Whitney U test were used to analyze differences in the pre-test and the post-test scores, time interval measurements and the differences between the two groups, respectively.
The findings of this study were as follows:
PImax, SIP, 12-minute walking distance and parts of BESC and ADL increased at the completion of the 8 weeks of training. PImax began to increase at the completion of 3-weeks of training then there was a plateau until the 7th week followed by a dramatic increase to a normal level. SIP gradually increased after 3 weeks of training. Only the MVV showed a little improvement with respiratory muscle training until the completion of the training. The effects between the two methods of respiratory muscle training measured by PImax, SIP, 12-minute walking distance and BESC were not significantly different except in the level of personal care of ADL´s.
From this study, it can be concluded that respiratory muscle training by use of the resistive inspiratory muscle´trainer is effective for the strengthening respiratory muscles, increasing PImax, SIP and 12-minute walking distance, and for improving BESC and ADL in COPD patients. Since the resistive respiratory muscle trainer is a simple and cheap inspiratory muscle training device, it is desirable to use it at home for rehabilitation of the COPD patient.
The main reasons for there being no difference in training effects using strength training only and a combination of strength and endurance training could be a variability of the subject´s characteristics and the small sample size.
Further comparative study is needed using more strictly controlled samples. Other surveysr and exploratory studies are also needed to identify normal values of SIP. Then it can be compared with the COPD patients and the effects of respiratory muscle training can be evaluated with the subjects´ nutritional status.
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