A positron emission tomography study of voluntarily and electrically contracted human quadriceps.

Within the domain of physical therapy, it has been mum isometric voluntary torque (MIVT) from each quadriceps. proposed that electrical stimulation programs might Then, MBF and MMRO2 were evaluated by PET be beneficial toward minimizing both muscular atroduring a bilateral simultaneous isometric exercise, phy and loss of oxidative capacity as a result of patient using ES (three excitative electrodes; pulse freimmobilization.5 quency 5 50 Hz; pulse width 5 0.25 ms) on one Within the fundamental research field, most auquadriceps and VC for the other. Except for the conthors assess biochemical parameters in stimulated traction mode, the exercise protocol remained unhuman muscle via biopsies3,8 or 31P nuclear magnetic changed for each quadriceps. The subjects were subresonance (NMR) techniques,12 but little is known mitted to bilateral contraction (5.5 s)–rest (5.5 s) about the muscular blood flow and the local aerobic cycles for 12 min, with a workload corresponding to metabolism in the electrostimulated human muscle. 20% of MIVT. The possibility to evaluate muscular blood flow (MBF) and muscular metabolic rate of oxygen Blood Flow Study. A bolus injection of 80 mCi of (MMRO2) by positron emission tomography (PET) H2O in the right forearm was administered. Emisand 15oxygen-labeled tracers was first described in the sion data were acquired during the 4 min between study of the human brain.6 the 8th and 12th min of exercise. We applied an adapted version of the bolus techData from arterial blood counting (240 3 1 s) nique4 allowing us to investigate the local MBF and and tomograms (20 3 12 s; 512 3 512 pixels; 30 MMRO2 in electrically stimulated (ES) and voluntarslices) (ECAT-II 951, Siemens) were processed using ily contracted (VC) quadriceps of healthy human suba system of simultaneous linear equations. jects. Six circular regions of interest, 2 cm in diameter, were selected in each quadriceps. Superficial regions METHODS were located in the vastus medialis (# 1), rectus femoEight healthy male volunteers [22.5 6 3.3 (SD) years] ris (# 2), and vastus lateralis (# 3) with the central first underwent an evaluation to determine the maxipoint at 2.5 cm from the skin surface. Deep regions (# 4, 5, 6) were selected below the three superficial regions with the central point at 5 cm from the skin surface. *Correspondence to: Dr. Marc Vanderthommen Oxygen Consumption Study. During another proceCCC 0148-639X/97/040505-03  1997 John Wiley & Sons, Inc. dure, 60 min after the injection of H2O, the subjects