Submaximal eccentric cycling in people with COPD: acute whole-body cardiopulmonary and muscle metabolic responses

Background

Eccentric cycling (ECC) may be an attractive exercise modality in COPD due to both low cardiorespiratory demand and perception of effort compared to conventional concentric cycling (CON) at matched mechanical loads. However, it is unknown whether ECC can be performed by individuals with COPD at an intensity able to cause sufficient metabolic stress to improve aerobic capacity.

Research question

What are the cardiopulmonary and metabolic responses to ECC in people with COPD and healthy volunteers when compared to CON at matched mechanical loads?

Study Design

and Methods: 13 individuals with COPD (mean ± SD age 64 ± 9 years, FEV 1 %pred 45 ± 19%, BMI 24 ± 4 kg.m -2, V̇O 2peak 15 ± 3 ml.kg -1.min -1) and 9 age matched controls (FEV 1 %pred 102 ± 13%, BMI 28 ± 5 kg.m -2, V̇O 2peak 23 ± 5 ml.kg -1.min -1), performed up to six 4 min bouts of ECC and CON at matched mechanical loads of increasing intensity. In addition, 12 individuals with COPD underwent quadriceps muscle biopsies before and after 20 min of ECC and CON at 65% peak power.

Results

At matched mechanical loads, oxygen uptake, minute ventilation, heart rate, systolic blood pressure, RER (all p<0.001), capillary lactate, perceived breathlessness and leg fatigue (p<0.05) were lower in both groups during ECC than CON. Muscle lactate content increased (p=0.008), and muscle phosphocreatine decreased (p=0.012) during CON in COPD, which was not evident during ECC.

Interpretation

Cardiopulmonary and blood lactate responses during submaximal ECC were less compared to CON at equivalent mechanical workloads in health and COPD, and this was confirmed at a muscle level in COPD. Submaximal ECC was well tolerated and allowed greater mechanical work at lower ventilatory cost. However, in people with COPD, a training intervention based on ECC is unlikely to stimulate cardiovascular and metabolic adaptation to the same extent as CON.