TY - JOUR

T1 - Economical estimates of oxygen uptake as a function of gait parameters for an ambulatory monitoring systems

AU - Takahashi, Tatsuhisa

AU - Wang, Shuoyu

AU - Okada, Akiyoshi

AU - Yanagida, Hirotaka

AU - Matsuo, Takashi

AU - Kuwayama, Takashi

AU - Niizeki, Kyuich

AU - Watanabe, Shinichi

AU - Natsui, Junichi

PY - 2009

Y1 - 2009

N2 - To examine a method to save time and money with empirical equations representing the relationship between oxygen uptake (VO2), walking speed (v), step frequency (SF), and step length (SL), we recorded the VO2 and SF of 7 young male volunteers walking at an increasing speed from 16.7 to 131.7 m min-1 with 5 m min-1 increments every 1 min, and at a decreasing speed from 106.7 m min-1 for 5 min to 16.7 m min-1 with 5 m min-1 decrements every 1 min on a level treadmill. SL was also computed by dividing walking speed by SF. The VO2 during decremental-speed walking was significantly greater compared to that during incremental-speed walking at corresponding speeds. The SF and SL could be expressed as a function of speed by SF=√13.18v and SL=0.076√ v, respectively, regardless of the different modes of walking with respect to speed. To estimate the VO2 during walking at different speeds, the results of the increments and decrements were combined by averaging them with respect to speed (VO2 = 1.454 × 10-4v2-6.5 × 10-3v+ 0.663, r=0.999, n=7). In a mathematical model of the cardiorespiratory system, the average values of VO2 at a given speed, even though there were on- and off-phase responses, could be predicted within 7.4% of the theoretical steady-state value. These results suggest that the VO2 against walking speed can be estimated by averaging the responses between the increments and decrements of moderate speeds. This could improve exercise tests for VO2 estimates in terms of time and money. In addition, by using the close relationship between SF and v, VO2 can be also expressed as a function of SF.

AB - To examine a method to save time and money with empirical equations representing the relationship between oxygen uptake (VO2), walking speed (v), step frequency (SF), and step length (SL), we recorded the VO2 and SF of 7 young male volunteers walking at an increasing speed from 16.7 to 131.7 m min-1 with 5 m min-1 increments every 1 min, and at a decreasing speed from 106.7 m min-1 for 5 min to 16.7 m min-1 with 5 m min-1 decrements every 1 min on a level treadmill. SL was also computed by dividing walking speed by SF. The VO2 during decremental-speed walking was significantly greater compared to that during incremental-speed walking at corresponding speeds. The SF and SL could be expressed as a function of speed by SF=√13.18v and SL=0.076√ v, respectively, regardless of the different modes of walking with respect to speed. To estimate the VO2 during walking at different speeds, the results of the increments and decrements were combined by averaging them with respect to speed (VO2 = 1.454 × 10-4v2-6.5 × 10-3v+ 0.663, r=0.999, n=7). In a mathematical model of the cardiorespiratory system, the average values of VO2 at a given speed, even though there were on- and off-phase responses, could be predicted within 7.4% of the theoretical steady-state value. These results suggest that the VO2 against walking speed can be estimated by averaging the responses between the increments and decrements of moderate speeds. This could improve exercise tests for VO2 estimates in terms of time and money. In addition, by using the close relationship between SF and v, VO2 can be also expressed as a function of SF.

KW - Step frequency

KW - Step length

KW - Walking exercise

KW - Walking speed

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M3 - Article

AN - SCOPUS:63049096013

SN - 0289-8020

VL - 30

SP - 219

EP - 225

JO - Therapeutic Research

JF - Therapeutic Research

IS - 2

ER -