Amanda Louise Ryan Ortiz1, Nicola Giovanelli2,3, Rodger Kram4. 1. Locomotion Laboratory, Integrative Physiology Department, University of Colorado, Boulder, CO, 80309-0354, USA. amanda.ortiz@colorado.edu. 2. Department of Medical and Biological Sciences, University of Udine, Udine, Italy. 3. School of Sport Sciences, University of Udine, Udine, Italy. 4. Locomotion Laboratory, Integrative Physiology Department, University of Colorado, Boulder, CO, 80309-0354, USA.
Abstract
PURPOSE: Vertical kilometer (VK) races, in which runners gain 1000 m of elevation in <5000 m of distance, are becoming popular. However, few studies on steep uphill running (>25°) exist. Previously, we determined that ~30° is the optimal angle for uphill running, costing the least amount of metabolic energy for a specific vertical velocity. To inform the training and strategy of VK racers, we quantified the metabolic cost of walking and running at various velocities up a 30° incline. METHODS: At 30°, 11 experienced runners (7 M, 4 F, 30.8 ± 7.9 years, 1.71 ± 0.08 m, 66.7 ± 9.4 kg) walked and ran for 5-min trials with 5-min rest between. Starting at 0.3 ms-1, we increased treadmill velocity by 0.1 ms-1 for each trial until subjects could not maintain the set velocity. We measured oxygen uptake (ml O2 kg-1 min-1) and metabolic power (W kg-1 = metabolic energy per unit time per unit body mass) and calculated metabolic costs of walking (C w) and running (C r) per unit distance (J kg-1 m-1). RESULTS: Oxygen uptake and metabolic power increased linearly with velocity. Between 0.3 and 0.7 ms-1, C w < C r. At 0.8 ms-1 there was no difference and extrapolation suggests that at faster velocities, running likely costs less than walking. CONCLUSION: On a 30° incline, metabolic power increases linearly with velocity. At speeds slower than 0.7 ms-1, walking requires less metabolic power than running (W kg-1) suggesting most VK racers should walk rather than run.
PURPOSE: Vertical kilometer (VK) races, in which runners gain 1000 m of elevation in <5000 m of distance, are becoming popular. However, few studies on steep uphill running (>25°) exist. Previously, we determined that ~30° is the optimal angle for uphill running, costing the least amount of metabolic energy for a specific vertical velocity. To inform the training and strategy of VK racers, we quantified the metabolic cost of walking and running at various velocities up a 30° incline. METHODS: At 30°, 11 experienced runners (7 M, 4 F, 30.8 ± 7.9 years, 1.71 ± 0.08 m, 66.7 ± 9.4 kg) walked and ran for 5-min trials with 5-min rest between. Starting at 0.3 ms-1, we increased treadmill velocity by 0.1 ms-1 for each trial until subjects could not maintain the set velocity. We measured oxygen uptake (ml O2 kg-1 min-1) and metabolic power (W kg-1 = metabolic energy per unit time per unit body mass) and calculated metabolic costs of walking (C w) and running (C r) per unit distance (J kg-1 m-1). RESULTS:Oxygen uptake and metabolic power increased linearly with velocity. Between 0.3 and 0.7 ms-1, C w < C r. At 0.8 ms-1 there was no difference and extrapolation suggests that at faster velocities, running likely costs less than walking. CONCLUSION: On a 30° incline, metabolic power increases linearly with velocity. At speeds slower than 0.7 ms-1, walking requires less metabolic power than running (W kg-1) suggesting most VK racers should walk rather than run.
Entities:
Keywords:
Cost of transport; Economy; Energetics; Uphill
Authors: D W Morgan; D R Bransford; D L Costill; J T Daniels; E T Howley; G S Krahenbuhl Journal: Med Sci Sports Exerc Date: 1995-03 Impact factor: 5.411