Exercising small muscle groups at a time allows higher muscle specific workloads compared to whole body aerobic exercises in people with chronic obstructive pulmonary disease (COPD). Whether similar effects also occur with partitioning exercise during low load/high-repetition resistance exercises is uncertain.
PURPOSE: To investigate the acute effects of partitioning exercise on exercise workload, exertional symptoms and quadriceps muscle fatigue during low load/high-repetition resistance exercises in people with COPD and healthy controls.
METHODS: We compared the acute physiological effects of single-limb (SL) versus two-limb (TL) execution of isokinetic knee-extension and of six low load/high-repetition elastic resistance exercises in 20 people with COPD (FEV1 = 38% predicted) and 15 healthy controls.
RESULTS: Among people with COPD, SL exercises resulted in higher exercise workloads during isokinetic knee-extension (17 ± 31%, p<0.05) and elastic exercises (rowing 17 ± 23%; leg curl 23 ± 21%; elbow flexion 19 ± 26%; chest press 14 ± 15%; shoulder flexion 33 ± 24% and knee-extension 24 ± 18%, all p<0.05). Muscle fatigue ratings were similar during SL compared to TL exercises, while dyspnea ratings were similar between conditions during isokinetic exercises and lower during SL compared to TL elastic exercises (p<0.05). In COPD, SL knee-extension resulted in greater quadriceps fatigue than TL knee-extension as evidenced by a greater fall in quadriceps potentiated twitch force after the former exercise (-24 ± 10 vs. -16 ± 8%, p=0.025). In healthy controls, partitioning exercise with SL exercise did not modify workload, quadriceps fatigue nor dyspnea achieved during the various exercises.
CONCLUSION: Partitioning exercise by exercising using a SL allowed higher muscle localized exercise workloads, larger amount of quadriceps muscle fatigue with lower or similar level of exertional symptoms during low load/high-repetition resistance exercises in people with advanced COPD.