Int J Sports Med 2010; 31(8): 548-554
DOI: 10.1055/s-0030-1251993
Physiology & Biochemistry

© Georg Thieme Verlag KG Stuttgart · New York

EMG Changes in Thigh and Calf Muscles in Fin Swimming Exercise

Y. Jammes1 , S. Delliaux1 , M. Coulange2 , C. Jammes1 , N. Kipson1 , C. Brerro-Saby1 , F. Bregeon1
  • 1Faculty of Medicine, UMR MD2 P2COE, Marseille, France
  • 2Hôpital Ste Marguerite, Hyperbaric Medicine, Marseille, France
Further Information

Publication History

accepted after revision March 01, 2010

Publication Date:
09 June 2010 (online)

Abstract

Because previous researchers have reported a reduced lactic acid production that accompanies a delayed or an absent ventilatory threshold (VTh) in water-based exercise, we hypothesized that the metaboreflex, activated by muscle acidosis, might be absent in fin swimming. This motor response, delaying the occurrence of fatigue, is characterized by a decreased median frequency (MF) of electromyographic (EMG) power spectrum. Seven healthy subjects performed a maximal fin swimming exercise protocol with simultaneous recordings of surface EMGs in vastus medialis (VM), tibialis anterior (TA) and gastrocnemius medialis (GM). We computed the root mean square (RMS) and MF and recorded the compound evoked muscle potential (M-wave) in VM. We also measured the propulsive force and oxygen uptake (VO2), and determined VTh. VTh was absent in 4/7 subjects and measured at 70–90% of VO2max in the other three. In the three studied muscles, the global EMG activity (RMS) increased while the MF decreased in proportion of VO2, the MF changes being significantly higher in VM (−29%) and GM (−39%) than in TA (−19%). Because no M-wave changes were noted, the MF decline was attributed to the recruitment of low-frequency, fatigue-resistant motor units. Our most important finding is the persistence of the metaboreflex even in a situation of reduced muscle acidosis.

References

Correspondence

Prof. Yves JammesMD, DSci 

Faculty of Medicine

UMR MD2 P2COE

Bd. Pierre Dramard

cedex 20

13916 Marseille

France

Phone: +33/491/69 8925

Fax: +33/491/69 8927

Email: yves.jammes@univmed.fr