Relationship between oxygen uptake slow component and surface EMG during heavy exercise in humans: influence of pedal rate.

Full Abstract

The aim of this study was to test the hypothesis that extreme pedal rates contributed to the slow component of oxygen uptake (VO(2) SC) in association with changes in surface electromyographic (sEMG) during heavy-cycle exercise. Eight male trained cyclists performed two square-wave transitions at 50 and 110 rpm at a work rate that would elicit a VO(2) corresponding to 50% of the difference between peak VO(2) and the ventilatory threshold. Pulmonary gas exchange was measured breath-by-breath and sEMG was obtained from the vastus lateralis and medialis muscles. Integrated EMG flow (QiEMG) and mean power frequency (MPF) were computed. The relative amplitude of the VO(2) SC was significantly higher during the 110-rpm bout (556+/-186 ml min(-1), P<0.05) with compared to the 50-rpm bout (372+/-227 ml min(-1)). QiEMG values increased throughout exercise only during the 110-rpm bout and were associated with the greater amplitude of the VO(2) SC observed for this condition (P<0.05). MPF values remained relatively constant whatever the cycle bout. These findings indicated a VO(2) SC at the two pedal rates but the association with sEMG responses was observed only at high pedal rate. Possible changes in motor units recruitment pattern, muscle energy turnover and muscle temperature have been suggested to explain the different VO(2) SC to heavy pedal rate bouts.

Author information

Author/s: Vercruyssen, Fabrice (F); Missenard, Olivier (O); Brisswalter, Jeanick (J);

Affiliation: Laboratoire d'Ergonomie Sportive et Performance, UFR STAPS, Université de Toulon-Var, 83957 La Garde Cedex, France. vercruyssen(-atsign-)univ-tln.fr

Journal and publication information

Publication Type: Journal Article

Journal: Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology (J Electromyogr Kinesiol), published in England. (Language: eng)

Reference: 2009-Aug; vol 19 (issue 4) : pp 676-84

Dates: Created 2009/06/15; Completed 2009/09/02;

PMID: 18424174, status: MEDLINE (last retrieval date: 9/4/2009, IMS Date: )

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