A Controlled Trial of the Effects of Leg Training on Breathing Pattern and Dynamic Hyperinflation in Severe COPD

Abstract

The effects of training on dynamic hyperinflation in stable chronic obstructive pulmonary disease (COPD) were investigated by using a controlled study of 28 subjects with FEV(1) = 42.5 (8.3 SD)%pred and 20 matched controls [FEV(1) = 44.9 (10.4)%pred]. Training consisted of spending 45 min/day, 4 days/week on a cycle-ergometer for six weeks. Maximal inspiratory and expiratory pressures (MIP and MEP), lung volumes, and two constant-work-rate (CWR) exercise tests (low- and high-intensity) were performed. Significant (p < 0.0l) improvements in the training group were observed in MIP [+8 (12) cmH(2)O], MEP [+18 (20) cmH(2)O], and endurance to high-intensity CWR [+7(5) min], and there were significant decreases in respiratory rate and end-expiratory lung volume (EELV) during both exercise tests. At 5 min, EELV decreased 0.1(0.08) L and 0.31(0.13) L and at end of exercise, EELV decreased by 0.09(0.07) L and 0.15(0.11) L respectively, for the moderate- and high-intensity tests. Dyspnea also decreased significantly at both exercise intensities. No changes were observed in the control group. Increased endurance showed independent significant (p < 0.05) correlation with changes in EELV, leg fatigue, and MEP. EELV changes showed a significant negative correlation with resting inspiratory capacity. We conclude that exercise training has beneficial effects on respiratory pattern and dynamic hyperinflation that may partially explain the reduction in dyspnea and the improvement in exercise tolerance.

Use of exercise testing in the evaluation of interventional efficacy: an official ERS statement

“…A decrease in isotime V′E may also be the consequence of reduced dead space volume to tidal volume ratio, because the metabolic and acid-base ventilatory demands of the task have been reduced or because the patient adopts a more efficient breathing pattern [45,101,114,115,118,127].…”

“…Inspiratory capacity is responsive to change during exercise following numerous pharmacological ( figure 6) and nonpharmacological interventions, including lung volume reduction and pulmonary rehabilitation [114,115,120], with effects in the range of 0.2-0.3 L or ∼15% pred [139].…”

“…In COPD patients the increase in tLIM following exercise training is likely to reflect improvements in the aerobic capacity of the trained muscles [111,112] and a delayed onset of metabolic acidosis [98,111,113], as well as slowed increases in operating lung volume and breathlessness [114,115]. Interventions designed to improve ventilatory function (i.e.…”

“…Inspiratory capacity is used increasingly as an outcome measure in clinical trials to test the efficacy of bronchodilators and other interventions [62,99,101,114,115,118,120,129,130].…”

Chest wall volume regulation during exercise in COPD patients with GOLD stages II to IV

“…Therapeutic interventions, such as bronchodilators [4,5], oxygen supplementation [6,7] and rehabilitative exercise training [8,9] improve exercise tolerance by reducing the degree of dynamic hyperinflation. Measurement of operational lung volumes is therefore crucial in order to evaluate the effectiveness of these therapeutic interventions.…”