Distribution of motor unit potential velocities in the biceps brachii muscle of sprinters and endurance athletes during prolonged dynamic exercises at low force levels

Klaver-Król, Ewa G.; Henriquez, Nizare R.; Oosterloo, Sebe J.; Klaver, Peter; Kuipers, Harm; Zwarts, Machiel J.

doi:10.1016/j.jelekin.2010.05.007

« Previous Next »Journal of Electromyography and Kinesiology
Volume 20, Issue 6 , Pages 1115-1124, December 2010

Distribution of motor unit potential velocities in the biceps brachii muscle of sprinters and endurance athletes during prolonged dynamic exercises at low force levels

Ewa G. Klaver-Król
- Department of Neurology and Clinical Neurophysiology, Ziekenhuis Groep Twente, Geerdinksweg 141, Hengelo, The Netherlands
- Department of Clinical Neurophysiology, Institute of Neurology, University Medical Centre, Nijmegen, The Netherlands
- Corresponding author. Address: P.O. Box 546, 7550 AM Hengelo, The Netherlands. Tel.: +31 74 2436 417; fax: +31 74 2905 599.
Nizare R. Henriquez
- Department of Neurology and Clinical Neurophysiology, Ziekenhuis Groep Twente, Geerdinksweg 141, Hengelo, The Netherlands
Sebe J. Oosterloo
- Faculty of Behavioral Sciences, University of Twente, Enschede, The Netherlands
Peter Klaver
- Children’s University Hospital, University of Zurich, Switzerland
Harm Kuipers
- Faculty of Health, Medicine and Life Sciences, University Maastricht, Maastricht, The Netherlands
Machiel J. Zwarts
- Department of Clinical Neurophysiology, Institute of Neurology, University Medical Centre, Nijmegen, The Netherlands
- Epilepsiecentrum Kempenhaeghe, Heeze, The Netherlands

Received 9 July 2009; received in revised form 19 May 2010; accepted 19 May 2010. published online 01 July 2010.

Abstract

In surface electromyography (sEMG), the distribution of motor unit potential (MUP) velocities has been shown to reflect the proportion of faster and slower propagating MUPs. This study investigated whether the distribution of MUP velocities could distinguish between sprinters (n=11) and endurance athletes (n=12) in not-specifically trained muscle (biceps brachii) during prolonged dynamic exercises at low forces. sEMG was acquired during 4min’ exercises: unloaded, 5%, 10% and 20% of maximal voluntary contraction (MVC). The features extracted from the sEMG were: the mean muscle conduction velocity – estimated using the inter-peak latency and cross-correlation methods, the within-subject skewness (expressing the proportions of faster and slower propagating MUPs) and the within-subject standard deviation of MUP velocities (SD-mup). Sprinters showed a greater proportion of faster propagating MUPs than endurance athletes. During fatigue, the SD-mup of sprinters broadened progressively, whereas that of endurance athletes did not. The findings suggest that sprinters conveyed a greater proportion of faster motor units than endurance athletes and that motor unit behavior during fatigue differed between groups. Thus, the distribution of MUP velocities enables distinction between a muscle of sprinters and endurance athletes during prolonged dynamic exercises at low forces.