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

© Georg Thieme Verlag Stuttgart · New York

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
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Publication Date:
09 March 2007 (online)

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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