ABSTRACT
The purpose of this study was to compare the effect of knee position on the magnitude of torque generated during the isokinetic movements of inversion and eversion at the ankle. Mean peak torque values at 30 and 120 degrees /sec were collected from 12 subjects, ages 21-31, from two test positions. The knee was stabilized in 10 degrees of flexion for the first test position and 70 degrees for the second. Additionally, mean peak amplitude of hamstring motor unit action potentials was compared between the two test positions to demonstrate differences in hamstring activity. At both speeds, mean peak torque values of the inversion-eversion movements, as well as mean peak amplitude of hamstring motor unit action potentials, was significantly lower in 10 degrees compared to 70 degrees of knee flexion (p < 0.01). It was concluded that isokinetic testing at the ankle with the knee in a close packed position, near full extension, provides a more valid representation of isolated muscular performance than testing with the knee in a loose packed position of midrange flexion.J Orthop Sports Phys Ther 1988;10(5):177-183.
ABSTRACT
Six trained males [mean maximal O2 uptake (VO2max) = 66 ml X kg-1 X min-1] performed 30 min of cycling (mean = 76.8% VO2max) during normoxia (21.35 +/- 0.16% O2) and hyperoxia (61.34 +/- 1.0% O2). Values for VO2, CO2 output (VCO2), minute ventilation (VE), respiratory exchange ratio (RER), venous lactate, glycerol, free fatty acids, glucose, and alanine were obtained before, during, and after the exercise bout to investigate the possibility that a substrate shift is responsible for the previously observed enhanced performance and decreased RER during exercise with hyperoxia. VO2, free fatty acids, glucose, and alanine values were not significantly different in hyperoxia compared with normoxia. VCO2, RER, VE, and glycerol and lactate levels were all lower during hyperoxia. These results are interpreted to support the possibility of a substrate shift during hyperoxia.
