Human Muscle Energetics During Voluntary and Electrically Induced Isometric Contractions as Measured by 31P NMR Spectroscopy

M. Vanderthommen; R. Gilles; P. Carlier; F. Ciancabilla; O. Zahlan; F. Sluse; J. M. Crielaard

doi:10.1055/s-2007-971131

International Journal of Sports Medicine, Table of Contents

Int J Sports Med 1999; 20(5): 279-283
DOI: 10.1055/s-2007-971131

Physiology and Biochemistry

Human Muscle Energetics During Voluntary and Electrically Induced Isometric Contractions as Measured by ³¹P NMR Spectroscopy

M. Vanderthommen¹ , R. Gilles² , P. Carlier³ , F. Ciancabilla² , O. Zahlan¹ , F. Sluse⁴ , J. M. Crielaard¹

¹Physical Medicine Department, University Hospital, Liège, Belgium
²Magnetic Resonance Unit, University Hospital, Liège, Belgium
³Institute of Myology, AFM and CEA, Paris, France
⁴Bioenergetic Laboratory, Chtemistry Institute, University of Liège, Belgium

Abstract

PDF Download

Electrical stimulation (ES) and voluntary contraction (VC) were compared in the quadriceps muscle of ten male volunteers. In both modes, a workload corresponding to 20 % off maximal voluntary contraction was applied during 64 isometric contraction (5.5 s)-relaxation (5.5 s) cycles. The protocols; were performed in a 1.5 T whole-body magnet. The Pi/PCr ratio and the intracellular pH (pHi) were monitored by ³¹P NMR spectroscopy during baseline, exercise and recovery periods, in a superficial region of the vastus medialis. During baseline, the Pi/PCr ratio (0.12 vs. 0.10) and the pHi (7.01 vs. 7.00) were comparable in both conditions. During exercise, the Pi/PCr ratio was (higher (0.36 vs. 0.14) and the pHi was lower (6.85 vs. 7.07) during ES than during VC. For the same external work production, these results reflect a different metabolic solicitation in the ES quadriceps than in the VC ones.

Key words

Muscle energetics - electrical stimulation - quadriceps - 31P NMR

PDF (572 kb)