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Purpose: This study aimed to investigate cardiorespiratory responses and intercostal muscle oxygenation during normocapnic hyperpnea exercise in chronic obstructive pulmonary disease (COPD). Methods : Twenty-two patients with COPD performed a cardiopulmonary cycling exercise test to assess peak oxygen consumption (V[spacing dot above]O2peak) and minute ventilation (V[spacing dot above] Epeak). They also performed a normocapnic hyperpnea exercise alone, at 50%-60% of V[spacing dot above] Epeak to exhaustion, using a respiratory device (Spirotiger) connected to a gas analyzer to monitor V[spacing dot above]O2, V[spacing dot above] E, and end-tidal CO2 partial pressure. Cardiac output, and intercostal and vastus lateralis muscle oxygenation were continuously measured during exercise using finger photoplethysmography and near-infrared spectroscopy, respectively. Arterial blood gases (arterial PCO2) and inspiratory capacity were obtained at rest and at the end of hyperpnea exercise. Results : The hyperpnea exercise lasted 576 +/- 277 s at a V[spacing dot above] E of 34.5 +/- 12.1 L[middle dot]min-1 (58% +/- 6% of V[spacing dot above] Epeak), a respiratory rate of 22 +/- 4 breaths per minute, and a tidal volume of 1.43 +/- 0.43 L. From rest to the end of hyperpnea exercise, V[spacing dot above]O2 increased by 0.35 +/- 0.16 L[middle dot]min-1 (P < 0.001), whereas end-tidal CO2 partial pressure and arterial PCO2 decreased by ~2 mm Hg (P = 0.031) and ~5 mm Hg (P = 0.002, n = 13), respectively. Moreover, inspiratory capacity fell from 2.44 +/- 0.84 L at rest to 1.96 +/- 0.59 L (P = 0.002). During the same period, heart rate and cardiac output increased from 69 +/- 12 bpm and 4.94 +/- 1.15 L[middle dot]min-1 at rest to 87 +/- 17 bpm (P = 0.002) and 5.92 +/- 1.58 L[middle dot]min-1 (P = 0.007), respectively. During hyperpnea exercise, intercostal deoxyhemoglobin and total hemoglobin increased by 14.26% +/- 13.72% (P = 0.001) and 8.69% +/- 12.49% (P = 0.003) compared with their resting value. However, during the same period, vastus lateralis oxygenation remained stable (P > 0.05). Conclusions : In patients with COPD, normocapnic hyperpnea exercise provided a potent cardiorespiratory physiological stimulus, including dynamic hyperinflation, and increased intercostal deoxyhemoglobin consistent with enhanced requirement for muscle O2 extraction. [ABSTRACT FROM AUTHOR]

Purpose: Muscle weakness is an observable consequence of limb muscle dysfunction in people with chronic obstructive pulmonary disease (COPD). The purpose of this review is to describe clinically applicable methods of muscle strength testing and functional tests that are associated with muscle strength in people with COPD. Summary of Key Points: Several tests and devices for evaluating muscle strength have been described in COPD. Isometric quadriceps strength testing, which is associated with clinical outcomes in COPD, can be reliably tested using fixed dynamometers or strain gauges in clinical and laboratory settings. Functional tests that are correlated with muscle strength in COPD include the Stair Climb Power Test, Sit-to-Stand test, and Timed Up and Go test. These tests are easy to conduct in the clinical setting and are relevant to daily activities; however, performance depends on factors such as balance and coordination in addition to leg muscle strength. Conclusions: Muscle strength assessment should be considered an integral part of the evaluation of people with COPD. Clinicians and researchers can select from a variety of valid and reliable tests to evaluate muscle strength based on their available resources and goals of the patient. [ABSTRACT FROM AUTHOR]

Exercising small muscle groups at a time allows higher muscle specific workloads compared with 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 (forced expiratory volume in 1 s = 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 with TL exercises, whereas dyspnea ratings were similar between conditions during isokinetic exercises and lower during SL compared with 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. Conclusions: Partitioning exercise by exercising using an 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. [ABSTRACT FROM AUTHOR]

Purpose: To compare the response to constant-workrate cycling exercise between the mouthpiece and the facemask in patients with chronic obstructive pulmonary disease (COPD). Methods: Ten patients with COPD (FEV1: 48 ± 14% pred, mean ± SD) performed two symptom-limited constant-workrate cycling exercise tests at 80% of their predetermined peak exercise capacity. One test was performed using a mouthpiece and the other with a facemask, in a random order. The endurance time to constant-workrate exercise was compared between the two interfaces. ...O2, ...CO2, ventilation (...E), inspiratory capacity, dyspnea Borg score, and heart rate responses during exercise were also compared. Results: Endurance time was similar between the two interfaces (mean difference ± SD, 30 ± 74 s, P = 0.23). Except for the end-exercise values, which were lower with the facemask, the ...O2, ...CO2, and ...E responses to submaximal exercise were similar between the two interfaces. Perception of dyspnea, inspiratory capacity, and heart rate kinetics were similar during the two exercise tests. No clear preference about either interface was expressed by the patients. Conclusion: The mouthpiece and the facemask can be used with comparable results to determine the endurance time to constant-workrate cycling exercise in patients with COPD. Compared with the mouthpiece, the end-exercise values for ...O2, ...CO2, and ...E were underestimated when a facemask was used. The similar responses in heart rate and symptom perception suggest that this could be due to an air leak at end-exercise with the facemask. [ABSTRACT FROM AUTHOR]