Cycle ergometer and inspiratory muscle training offer modest benefit compared with cycle ergometer alone: a comprehensive assessment in stable COPD patients

Abstract

Background: Cycle ergometer training (CET) has been shown to improve exercise performance of the quadriceps muscles in patients with COPD, and inspiratory muscle training (IMT) may improve the pressure-generating capacity of the inspiratory muscles. However, the effects of combined CET and IMT remain unclear and there is a lack of comprehensive assessment.

Materials and methods: Eighty-one patients with COPD were randomly allocated to three groups: 28 received 8 weeks of CET + IMT (combined training group), 27 received 8 weeks of CET alone (CET group), and 26 only received 8 weeks of free walking (control group). Comprehensive assessment including respiratory muscle strength, exercise capacity, pulmonary function, dyspnea, quality of life, emotional status, nutritional status, and body mass index, airflow obstruction, and exercise capacity index were measured before and after the pulmonary rehabilitation program.

Results: Respiratory muscle strength, exercise capacity, inspiratory capacity, dyspnea, quality of life, depression and anxiety, and nutritional status were all improved in the combined training and CET groups when compared with that in the control group (P<0.05) after pulmonary rehabilitation program. Inspiratory muscle strength increased significantly in the combined training group when compared with that in the CET group (ΔPI_max [maximal inspiratory pressure] 5.20±0.89 cmH₂O vs 1.32±0.91 cmH₂O; P<0.05). However, there were no significant differences in the other indices between the two groups (P>0.05). Patients with weakened respiratory muscles in the combined training group derived no greater benefit than those without respiratory muscle weakness (P>0.05). There were no significant differences in these indices between the patients with malnutrition and normal nutrition after pulmonary rehabilitation program (P>0.05).

Conclusion: Combined training is more effective than CET alone for increasing inspiratory muscle strength. IMT may not be useful when combined with CET in patients with weakened inspiratory muscles. Nutritional status had slight impact on the effects of pulmonary rehabilitation. A comprehensive assessment approach can be more objective to evaluate the effects of combined CET and IMT.

Keywords: chronic obstructive pulmonary disease; comprehensive assessment; cycle ergometer; exercise performance; inspiratory muscle training; pulmonary rehabilitation.

Figure 1

Changes of ventilatory pattern, HR, SPO₂, and Borg scale during CPET. Notes: Data are presented as mean ± SE unless otherwise stated; Δ, difference (after minus before intervention); P-value results of analysis of repeated measures analysis of variance (ANOVA) comparison of the differences between groups. Abbreviations: CET, cycle ergometer training; IMT, inspiratory muscle training; AT, anaerobic threshold; VE, minute ventilation; Rf, respiratory frequency; VT, tidal volume; SPO₂, pulse oxygen saturation; HR, heart rate; RER, respiratory exchange ratio; CPET, cardiopulmonary exercise testing.

Figure 2

Flow diagram for studies included. Abbreviation: CET, cycle ergometer training.