Factors Contributing to the Walk-to-Run Transition in Human Gait

Thomas John Otley, Nicholas Yowell Kulaga

Abstract


The study examined factors that contribute to the walk-to-run (WTR) transition occurring in human gait.  Specifically, the purposes of the study included: (A) confirmation of the hypothesis (Kram et al., 1997; Usherwood, 2005; Usherwood et al., 2012) that the preferred WTR for humans occurs at a Fr =0.50;  (B) determination of a similar estimate for a maximum WTR transition velocity (e.g., Fr >0.60);  (C) testing the following hypothesis: As velocity increases, rather than taking longer steps, subjects (1) take shorter steps, and (2) increase step frequency.   The Froude ratio (Fr) is calculated as Fr = v2 / gL, where v = velocity, g = acceleration due to gravity (9.81 m/s2), and L = leg length.  Twenty volunteers (10 male, 10 female) participated.  Leg length for each subject was measured using a published protocol.  To determine (A) preferred WTR, subjects walked on a level treadmill at a comfortable velocity. Every 15 seconds, velocity was increased 0.045 m/sec until the subject made an observable gait transition and velocity was slowed until the subject walked again. The procedure was repeated for a total of three trials. Procedure for (B) was the same as the (A) except that the subjects were instructed to hold their walking gait as long as possible to determine maximum WTR velocity. Procedure for (C) involved filming each subject during condition (B) to determine step length and step frequency.  Frame-by-frame analysis was used to determine changes in step length/frequency in response to changes in velocity.  Preliminary results for each part of the study were as follows: (A) mean Fr = 0.47 for the preferred WTR; (B) mean Fr = 0.79 for the maximum WTR; (C) subjects did not shorten step length as had been expected; rather subjects maintained step length and increased step frequency prior to maximum WTR.


Keywords


Froude ratio; Walk-to-Run transition; Inverted pendulum; Transition velocity

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