Metabolic and performance responses to uphill and downhill running in distance runners

Distance running performance is slower on hilly race courses than flat courses even when the start and finish are at the same elevation, resulting in equal amounts of uphill and downhill running. The physiological mechanism limiting performance on these courses is not known. We examined the effects of uphills and downhills with 11 trained male distance runners running three 30 min self-paced competitive races on a treadmill. Race courses consisted of five, 6 min stages. Percent grades were: course A (0, 0, 0, 0, 0), course B (0, +5, 0, -5, 0) and course C (0, -5, 0, +5, 0). Pace, oxygen consumption (VO2), heart rate (HR), blood lactate (LA), and rating of perceived exertion (RPE) did not change significantly (P greater than 0.05) over stages on the control course A. Pace changed inversely with percent grade on courses B and C. The increase in downhill running pace was inadequate to maintain a level VO2 during the race. LA increased on the uphill stages even though running pace decreased. The running paces for courses B and C were slower (P less than 0.05) than course A by 2.8% and 2.4%, respectively. Runners do not maintain constant energy expenditure when racing on hilly courses. Lactate accumulated on uphill stages even though pace decreased. Running pace increased on downhills but not enough to maintain a constant VO2.