@article {RibeiroP3570, author = {Fernanda Ribeiro and Val{\'e}rie Coats and Didier Saey and Fran{\c c}ois Maltais}, title = {Effects of a low-intensity single-leg exercise on fatigue and muscle oxygenation in patients with chronic obstructive pulmonary disease (COPD)}, volume = {42}, number = {Suppl 57}, elocation-id = {P3570}, year = {2013}, publisher = {European Respiratory Society}, abstract = {In COPD, single-leg exercises allow to study muscle dysfunction mechanisms in isolation from exagerated ventilatory demand and dyspnea. Therefore, we studied the effect of a knee-extension exercise on quadriceps fatigue and its possible association with cardiorespiratory demand and oxygen extraction at the muscle level.Methods: Eight patients with moderate-to-severe COPD (FEV1 = 45 {\textpm} 13\% of predicted) performed an isokinetic knee-extension exercise at 40\% of their maximal peak torque. Quadriceps isometric maximal voluntary contraction (MVC) and magnetic-stimulated twitch (Twpot) were measured before and after exercise to characterize muscle fatigue. Cardiorespiratory demand and muscle oxygenation (deoxyhemoglobin/myoglobin concentration, [HHb], by near-infrared spectroscopy) were assessed during exercise.Results: Patients performed a total of 7.4 {\textpm} 1.0 kJ of muscle work, which resulted in a reduction of both MVC and Twpot of -11 {\textpm} 8 \% and -22 {\textpm} 25 \%, respectively. Five patients presented muscle fatigue (\> 15 \% reduction in Twpot). At the end of exercise, dyspnea and leg-fatigue Borg scores were 2.0 {\textpm} 1.0 and 0.7 {\textpm} 0.8, respectively. No significant changes in muscle oxygenation (Δ[HHb] = 13 {\textpm} 12\%, p = 0.08) were seen. Changes in muscle oxygenation were not associated with muscle strength loss. Peak minute ventilation and oxygen uptake represented, on average, 50\% and 41\% of peak value achieved during a symptom-limited maximal exercise test.Conclusion: Despite low cardiorespiratory demand and exercise load, a single-leg exercise induced muscle fatigue in the absence of muscle deoxygenation in some patients with moderate-to-severe COPD.}, issn = {0903-1936}, URL = {https://erj.ersjournals.com/content/42/Suppl_57/P3570}, eprint = {https://erj.ersjournals.com/content/42/Suppl_57/P3570.full.pdf}, journal = {European Respiratory Journal} }