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Plantar loading and cadence alterations with fatigue

WILLSON, JOHN D.; KERNOZEK, THOMAS W.

Medicine & Science in Sports & Exercise: December 1999 - Volume 31 - Issue 12 - p 1828
Applied Sciences: Biodynamics

WILLSON, J. D., and THOMAS W. KERNOZEK. Plantar loading and cadence alterations with fatigue. Med. Sci. Sports Exerc., Vol. 31, No. 12, pp. 1828–1833, 1999.

Purpose The purpose of this investigation was to identify changes in loading characteristics of the foot associated with fatigue during running.

Methods Nineteen healthy subjects ranging from 20 to 30 yr (mean = 22.3, SD = 2.4) were equipped with the Pedar in-shoe measurement system (Novel GmbH) for the assessment of plantar loading. After acclimation to the treadmill, subjects were progressed through the Ohio State protocol for exercise testing until fatigue was reported using Borg’s RPE scale. Six right footsteps were recorded at 150 Hz for each subject’s comfortable running pace under normal and fatigued conditions. A series of repeated measures multiple analysis of variance was performed for all dependent variables analyzed in this study including peak force (PF), force-time integral (FTI), peak pressure (PP), and pressure-time integral (PTI) for all regions of the plantar surface.

Results Decreased step time, significantly smaller values under the heel for PP, PF, FTI, CT, and PTI, and trends toward increased medial forefoot loading were identified while subjects were running under fatigued conditions (α < 0.05).

Conclusion These results suggest that subjects change running technique and plantar surface loading characteristics in response to fatigued conditions through increased cadence, decreased loading of the heel, and increased medial forefoot loading.

Department of Physical Therapy, University of Wisconsin-La Crosse, WI; and Gundersen Lutheran Sports Medicine, La Crosse, WI

Submitted for publication May 1998.

Accepted for publication February 1999.

Address for correspondence: Thomas W. Kernozek, Physical Therapy Department, 2032 Cowley Hall, University of Wisconsin-La Crosse, WI 54601. E-mail: kernozek@mail.uwlax.edu.

© 1999 Lippincott Williams & Wilkins, Inc.