Year: 2013
Type: dissertation
Abstract: Prehistoric man relied greatly on migration by foot, hence the inherent need \nof the human body to minimize energy expenditure. Through self-selecting a preferred \nwalking speed (PWS) humans are capable of minimizing energy expenditure. The purpose \nof this study was to measure the energetic cost and kinematics of gait that occur \nwith changes in walking speed. The PWS of eight women and six men was first determined. \nSubjects then walked on a level treadmill starting at 3.2 km/hr and speed was \nincreased by 0.80 km/hr every 10 minutes up to 7.2 km/hr. Metabolic parameters (VO2, \nVCO2, RER, and HR) were collected during the last 2 minutes of each speed. Step \nlength (SL) and step rate (SR) were assessed during the last minute at each speed. PWS \nwas 4.33 ?? 0.56 km/hr. VO2 (L/min), RER, HR, SL, and SR all increased significantly \nat each walking speed. Regardless of how VO2 was expressed, it increased in a curvilinear fashion with increasing walking speed (p < 0.05). The O2 cost of transport \nwas significantly higher at 3.2 km/hr than at walking speeds of 4.0 km/hr (p < 0.05), 4.8 \nkm/hr (p < 0.05), and 5.6 km/hr (p = 0.006). The O2 cost of transport at 7.2 km/hr was \nsignificantly higher than at 3.2 km/hr (p = 0.038), 4.0 km/hr (p < 0.05), 4.8 km/hr (p < \n0.05), 5.6 km/hr (p < 0.05), and 6.4 km/hr (p < 0.05). Percent of energy from fat decreased \nfrom 90 ?? 8.32% to 62 ?? 13.59 (p < 0.05), while the percent of energy from \nCHO increased from 10 ?? 8.17% to 43 ?? 21.58 % (p < 0.05) from 3.2 to 7.2 km/hr. SR \nat 3.2 km//hr was 1.59 ?? 0.03 steps per second and increased to 2.26 ?? 0.04 steps per \nsecond at 7.2 km/hr. SL also increased from 0.55 ?? 0.04 m to 0.89 ?? 0.07 m from 3.2 \nkm/hr to7.2 km/hr. The O2 cost of transport was minimized at or near the PWS for all \nsubjects. With greater walking speed oxygen consumption (VO2) increased in a curvilinear \nmanner, energy from CHO increased, and energy from fat decreased. Both SR \nand SL increased with increased walking speed. Greater O2 cost below the PWS may be \nexplained by the inefficiency of a shorter SL.
Author: Ashleigh M. Huynh
Language: English
Subfield: Physiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2246304607