There is very little information about the effect of inspiratory muscle training on inspiratory flow (V'I) and thus on power output (PO) in patients with chronic obstructive pulmonary disease (COPD). In this study we aimed to evaluate the changes induced by training on the determinants of PO. Thirty one patients with severe COPD were randomly divided into: Group 1, trained with 30% maximal inspiratory pressure (PI,max); Group 2, with 10% PI,max; and Group 3 also trained with 30% PI,max, but the breathing pattern was evaluated while performing the training manoeuvres along inspiratory muscle training (IMT). All groups used a threshold device for 10 weeks. The PO for each of the loads during an incremental threshold test was evaluated prior to and after training. Maximal PO (POmax) increased in all groups, but the increment was higher in groups trained with 30% PI,max (p<0.005), mainly due to an increase in V'I. Group 3 showed a progressive increase in V'I (p<0.001) during the training manoeuvres in spite of an increase in load along IMT. In addition, the load after IMT was overcome with a shorter inspiratory time (tI) (p<0.02), a smaller tI/total duration of the respiratory cycle (t(tot)), (p<0.001) with no change in tidal volume or t(tot). The increment in POmax in this group correlated with the V'I generated while training (r=0.85; p<0.0001). We conclude that in patients with chronic obstructive pulmonary disease, the use of an intermediate threshold load for training improves power output mainly by increasing inspiratory flow, an effect consistent with an increase in shortening velocity of inspiratory muscles.
PMID: 9543266 DOI: 10.1183/09031936.98.11010028

There is very little information about the effect of inspiratory muscle training on inspiratory flow (V'I) and thus on power output (PO) in patients with chronic obstructive pulmonary disease (COPD). In this study we aimed to evaluate the changes induced by training on the determinants of PO. Thirty one patients with severe COPD were randomly divided into: Group 1, trained with 30% maximal inspiratory pressure (PI,max); Group 2, with 10% PI,max; and Group 3 also trained with 30% PI,max, but the breathing pattern was evaluated while performing the training manoeuvres along inspiratory muscle training (IMT). All groups used a threshold device for 10 weeks. The PO for each of the loads during an incremental threshold test was evaluated prior to and after training. Maximal PO (POmax) increased in all groups, but the increment was higher in groups trained with 30% PI,max (p<0.005), mainly due to an increase in V'I. Group 3 showed a progressive increase in V'I (p<0.001) during the training manoeuvres in spite of an increase in load along IMT. In addition, the load after IMT was overcome with a shorter inspiratory time (tI) (p<0.02), a smaller tI/total duration of the respiratory cycle (t(tot)), (p<0.001) with no change in tidal volume or t(tot). The increment in POmax in this group correlated with the V'I generated while training (r=0.85; p<0.0001). We conclude that in patients with chronic obstructive pulmonary disease, the use of an intermediate threshold load for training improves power output mainly by increasing inspiratory flow, an effect consistent with an increase in shortening velocity of inspiratory muscles.
PMID: 9543266 DOI: 10.1183/09031936.98.11010028

Cycle ergometer training plays an important role in the rehabilitation of patients with chronic obstructive pulmonary disease (COPD), but the usefulness of specific inspiratory muscle training as part of pulmonary rehabilitation remains uncertain. To determine whether inspiratory muscle training could intensify the known beneficial effects of cycle ergometer training on exercise performance in these patients, we compared the effect of an 8 week inspiratory muscle training combined with cycle ergometer training with that of an 8 week cycle ergometer training alone on inspiratory muscle performance and general exercise capacity. Patients were randomly assigned to the two training groups; 21 patients received additional inspiratory muscle training (Group 1) and 21 did not (Group 2). Maximal sniff assessed oesophageal and transdiaphragmatic pressures served as parameters for global inspiratory muscle strength and diaphragmatic strength, respectively. The duration for which the patient could breathe against a constant inspiratory pressure load was used as an index of inspiratory muscle endurance. Exercise capacity was determined by an incremental symptom-limited cycle ergometer test. After the training period, inspiratory muscle performance improved significantly in the patients with inspiratory muscle training, but not in those without. Both training regimens increased maximal power output and oxygen uptake, but this improvement was significantly greater in the patients with inspiratory muscle training than in those without.(ABSTRACT TRUNCATED AT 250 WORDS).
PMID: 7713205 DOI: 10.1183/09031936.94.07122205

We compared, in a controlled clinical trial, the effect of specific inspiratory muscle training combined with general exercise reconditioning, for six months, with that of general exercise reconditioning alone on inspiratory muscle strength, endurance, and exercise performance in patients with COPD. Thirty-six patients were recruited into three groups; 12 patients received specific inspiratory muscle training combined with general exercise reconditioning, 12 patients underwent general exercise reconditioning alone, and the remaining 12 patients received no training. Specific inspiratory muscle training, for six months, improved the inspiratory muscle strength and endurance in patients with COPD. This training combined with general exercise reconditioning also provided improvement in exercise tolerance, and this improvement was significantly greater than that of general exercise reconditioning alone.
PMID: 1424850 DOI: 10.1378/chest.102.5.1351

In most chronic obstructive pulmonary disease (COPD) patients, dyspnoea and functional exercise capacity may improve as a result of inspiratory muscle training (IMT). However, the long-term benefits of IMT have been investigated to a much lesser extent. The present study investigated the short-term and long-term benefits of IMT on inspiratory muscle performance (strength and endurance), exercise capacity and the perception of dyspnoea. Thirty-eight patients with significant COPD had 3 months of basic IMT and were then randomised into a group that received maintenance IMT for the next year, and a group that got training with very low load. Following the basic training there was a statistically significant increase in inspiratory muscle performance, 6-min walk test (6MWT), and a decrease in the dyspnoea. During the second stage of the study, the training group continued to maintain the improvement in all parameters, while there was already deterioration in the inspiratory muscle performance, exercise capacity and dyspnoea in the low intensity group during the 6-12 month period. The present study concludes that, in patients with significant chronic obstructive pulmonary disease, inspiratory muscle training results in improvement in performance, exercise capacity and in the sensation of dyspnoea. The benefits of 12-weeks of inspiratory muscle training decline gradually over 1 yr of follow-up if maintenance training is not performed.
PMID: 14738232 DOI: 10.1183/09031936.03.00059503