This study analyzed the physiological responses of male long-distance runners (N = 20) running at critical velocity. Critical velocity was assessed on the track for 800 m, 1,500 m, and 5,000 m and on a treadmill at 11, 12, and 13 mph. Heart rate, ventilation, oxygen intake, carbon dioxide output, and blood lactate were measured during a 20-minute flat run on a treadmill at 85%, 100%, and 115% of critical velocity. A significant correlation of r = .99 was found between critical velocity and 5,000 m performance. Critical velocity measured on the track was similar to that measured on the treadmill. During 85% of critical-velocity running, ventilatory factors were in steady state but heart rate increased over time. Implication. Critical velocity running does not elicit steady-state physiological responses. Steady-state training will not increase specific speed for particular distance races.
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