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Sinusoidal high‐intensity exercise does not elicit ventilatory limitation in chronic obstructive pulmonary disease
Author(s) -
Porszasz Janos,
Rambod Mehdi,
van der Vaart Hester,
Rossiter Harry B.,
Ma Shuyi,
Kiledjian Rafi,
Casaburi Richard
Publication year - 2013
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.2012.070375
Subject(s) - cycle ergometer , copd , incremental exercise , cardiology , medicine , ventilation (architecture) , work rate , pulmonary disease , respiratory minute volume , ventilatory threshold , intensity (physics) , heart rate , vo2 max , respiratory system , physics , blood pressure , quantum mechanics , thermodynamics
New Findings• What is the central question of this study? Is it possible for patients with chronic obstructive pulmonary disease to avoid ventilatory limitation during high‐intensity exercise by using a fast‐fluctuating sinusoidal exercise task? • What is the main finding and its importance? Sinusoidal exercise, with a cycle time of 60 s superimposed upon a mean work rate at critical power, resulted in minimal fluctuations in the exercise ventilation. Thus, high‐intensity exercise, with excursions well above peak aerobic power, was sustained for up to 20 min in chronic obstructive pulmonary disease patients, and the end‐exercise ventilation was less than peak. This exercise protocol may prove beneficial in rehabilitative exercise training programmes where large gains in skeletal muscle adaptation are the goal.During exercise at critical power (CP) in chronic obstructive pulmonary disease (COPD) patients, ventilation approaches its maximum. As a result of the slow ventilatory dynamics in COPD, ventilatory limitation during supramaximal exercise might be escaped using rapid sinusoidal forcing. Nine COPD patients [age, 60.2 ± 6.9 years; forced expiratory volume in the first second (FEV 1 ), 42 ± 17% of predicted; and FEV 1 /FVC, 39 ± 12%] underwent an incremental cycle ergometer test and then four constant work rate cycle ergometer tests; tolerable duration ( t lim ) was recorded. Critical power was determined from constant work rate testing by linear regression of work rate versus 1/ t lim . Patients then completed fast (FS; 60 s period) and slow (SS; 360 s period) sinusoidally fluctuating exercise tests with mean work rate at CP and peak at 120% of peak incremental test work rate, and one additional test at CP; each for a 20 min target. The value of t lim did not differ between CP (19.8 ± 0.6 min) and FS (19.0 ± 2.5 min), but was shorter in SS (13.2 ± 4.2 min; P < 0.05). The sinusoidal ventilatory amplitude was minimal (37.4 ± 34.9 ml min −1 W −1 ) during FS but much larger during SS (189.6 ± 120.4 ml min −1 W −1 ). The total ventilatory response in SS reached 110 ± 8.0% of the incremental test peak, suggesting ventilatory limitation. Slow components in ventilation during constant work rate and FS exercises were detected in most subjects and contributed appreciably to the total response asymptote. The SS exercise was associated with higher mid‐exercise lactate concentrations (5.2 ± 1.7, 7.6 ± 1.7 and 4.5 ± 1.3 mmol l −1 in FS, SS and CP). Large‐amplitude, rapid sinusoidal fluctuation in work rate yields little fluctuation in ventilation despite reaching 120% of the incremental test peak work rate. This high‐intensity exercise strategy might be suitable for programmes of rehabilitative exercise training in COPD.