To study the relationship among respiratory and lower limb muscle strength and exercise capacity in patients with chronic obstructive pulmonary disease(COPD).
We studied 15 patients with COPD (9 men, 64.4 ± 8.2 years). All patients performed spirometry and assessment of respiratory muscle strength. Quadriceps strength and endurance was evaluated by the one-repetition maximum test (1RM) and one-minute sit-to-stand test. The exercise capacity was assessed through the six-minute walk test.
Mean forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and FVC/FEV1 were 70.7 ± 16.9%, 42.6 ± 19.5% and 47.2 ± 13.6, respectively. The maximal inspiratory pressure (PImax) was −78.2 ± 24.4 cmH2O and the maximal expiratory pressure (PEmax) was 98.5 ± 26.4 cmH2O. The mean values of 1RM test and sit-to-stand test were 17.2 ± 7.4 kg and 26.4 ± 5.1 repetitions, respectively. The walked distance was 426 ± 68.1 m. The walked distance was associated with PImax (r = −0.615; p = 0.01) and PEmax (r = 0.641; p = 0.01); there was no association between walked distance and quadriceps muscle strength (p = 0.50).
We conclude that maximal respiratory pressures but not quadriceps muscle strength correlated with the exercise performance measured by walked distance in COPD patients.
Further studies are needed to understand the influence of respiratory and quadriceps muscle strength on exercise performance in COPD patients.
Marli Knorst, No Financial Disclosure Information; No Product/Research Disclosure Information