This study assessed initial foot contact patterns (IFCP) in a large group of distance runners and the effect of speed on the IFCP.
We determined the strike index to classify the runners in IFCP groups, at four speeds (3.2, 4.1, 5.1, and 6.2 m·s−1), by measuring center of pressure (COP) with a 2-m plantar pressure plate. Such a system allows a direct localization of the COP on the plantar footprint and has a low threshold value (2.7 N·cm−2), resulting in more accurate COP data at low ground reaction forces than when obtained from force plate.
The IFCP distribution evolves from mostly initial rearfoot contact (IRFC) (82%) at 3.2 m·s−1 to more anterior foot contacts with an approximately equal distribution of IRFC (46%) and initial midfoot or forefoot contact (54%) at 6.2 m·s−1. Approximately 44% of the IRFC runners showed atypical COP patterns with a fast anterior displacement of the COP along the lateral shoe margin. Apart from the different COP patterns, these atypical IRFC were also characterized by a significantly higher instantaneous vertical loading rate than the typical IRFC patterns.
The IFCP distribution changes were due to intraindividual alterations in IFCP at higher speeds. That is, 45% of the runners made one or even two “transitions” toward a more anterior IFCP (and 3% shows some other type of transition between initial foot contact styles as speed increases). However, 52% of the runners remained with the same IFCP.
1Department of Movement and Sports Sciences, Ghent University, Ghent, BELGIUM; and 2Exeter Research, Inc., Brentwood, NH
Address for correspondence: Bastiaan Breine, MS, Watersportlaan 2, 9000 Gent, Belgium; E-mail: email@example.com.
Submitted for publication May 2013.
Accepted for publication December 2013.
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