Kouwenhove, L. van and Krops, L.A. and Otten, prof. dr. E. (2014) Leg Stiffness Regulation in Human Running at High Velocities: Exploring the Extremities. thesis, Human Movement Sciences.
Full text available on request.Abstract
Simplifying the behaviour of the body during running exercise, is an important element in running studies. The behaviour is very well simulated as an oscillating mass-spring systems that bounces on a certain step frequency. In order to increase or decrease the running speed and therefore the oscillating frequency of the system, the spring parameters are adjusted. Since normal springs have a fixed stiffness, the vertical leg stiffness of human legs is more variable. Various studies show leg spring changes, but generally at lower velocities. The goal of this study is to determine the changes to the leg spring stiffness when runners alter their step frequency at high velocities. Eighteen experienced runners ran at three speed conditions of 5-6-7 m/s or 5-7-8 m/s, depending on their maximum velocity, over a distance of 50 meters. For each speed condition, the preferred step frequency was determined. After that, the runners were required to alter their step frequency by use of metronome. If the runner was not able to a) maintain speed or b) maintain the imposed step frequency, the protocol stopped. Results show a narrowing range of frequencies towards maximal velocities. Changes in frequency are basically established by changes in the flight time. Only at high frequency running, the contact time is decreased. Kinematic analysis show primarily adjustments of the stance leg at the beginning and end of the stance phase and significant higher leg spring stiffness at forefoot strikers. In conclusion, we found that runners can accommodate to different step frequencies over a range of fixed speed conditions. Vertical leg stiffness is and maximal force production are mainly adjusted respectively for high and low frequency running. The range in which stride parameters and leg stiffness can be adjusted may therefore be an important parameter for running performance at high velocities. Keywords: Locomotion; Spring-mass model, Leg Stiffness; Biomechanics; Motor control.
| Item Type: | Thesis (UNSPECIFIED) |
|---|---|
| Faculty: | Medical Sciences |
| Date Deposited: | 01 Apr 2022 13:25 |
| Last Modified: | 01 Apr 2022 14:03 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/3030 |
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