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Dietary nitrate (NO₃⁻) supplementation with beetroot juice (BR) over 4–6 days has been shown to reduce the O₂ cost of submaximal exercise and to improve exercise tolerance. However, it is not known whether shorter (or longer) periods of supplementation have similar (or greater) effects. We therefore investigated the effects of acute and chronic NO₃⁻ supplementation on resting blood pressure (BP) and the physiological responses to moderate-intensity exercise and ramp incremental cycle exercise in eight healthy subjects. Following baseline tests, the subjects were assigned in a balanced crossover design to receive BR (0.5 l/day; 5.2 mmol of NO₃⁻/day) and placebo (PL; 0.5 l/day low-calorie juice cordial) treatments. The exercise protocol (two moderate-intensity step tests followed by a ramp test) was repeated 2.5 h following first ingestion (0.5 liter) and after 5 and 15 days of BR and PL. Plasma nitrite …