The effect of different exercise modalities on dyspnea and leg fatigue in healthy subjects

• Dyspnea was not different for different exercises at a given cardiopulmonary stress.
• Leg fatigue and dyspnea were not modulated by different muscle activation patterns.
• Dyspnea reflected the overall level of ventilation across different exercise modes.
• Leg fatigue reflected the overall level of muscular work across different modes.

BackgroundThis study documents the impact of different exercise modalities on dyspnea and leg fatigue during equivalent cardiopulmonary stress in healthy subjects.MethodologyFollowing a familiarization, 20 subjects (age 21–44 years; 8 males) performed six 5-min exercise tests, randomized among: 2 steep slope treadmill tests (25% grade), 2 lesser slope treadmill tests (12% grade) and 2 bicycle tests on 3 separate days. Subjects reported either dyspnea or leg fatigue during each test. Oxygen consumption (V˙O2), ventilation (V˙E), respiratory rate (fR) and heart rate (HR) were measured during each test.ResultsV˙O2,V˙E, HR, dyspnea and leg fatigue were not significantly different among the three exercise conditions (p > 0.05).ConclusionThese findings indicate that at equivalent levels of cardiopulmonary stress reflected by similar levels of V˙O2 and heart rate, the perceived level of exertional dyspnea is not influenced by different patterns of neuromuscular activity. Similarly, the intensity of leg fatigue primarily reflects whole body work and is independent of different patterns of neuromuscular activity.