Howard Smithline1,2, Long Ngo3,4, Elyse Linson1, Robert Greenman4,5
1Emergency Medicine, Baystate Medical Center, Springfield, MA, United States; 2Tufts University Medical School, Boston, MA, United States; 3General Medicine & Primary Care, Beth Israel Deaconess Medical Center, Boston, MA, United States; 4Harvard Medical School, Boston, MA, United States; 5Radiology, Beth Israel Deaconess Medical Center, Boston, MA, United States
The time constant (tau) of post-exercise phosphocreatine (PCr) recovery curve, reflects oxidative metabolism. Tau-PCr calculated from repeated low-intensity exercise may be more reliable than a single low-intensity or high-intensity exercise. Five volunteers performed three low-intensity and one high-intensity plantar flexion protocol on two days. 31P spectra were acquired every 10 seconds. Monoexponential curves were fitted to normalized PCr yielding tau and its SE. Weighted (inverse variance) intraclass correlation coefficients (ICC) were calculated. ICC increased from 0.39 to 0.92 by using repeated measures for low-intensity exercise. The ICC for the high-intensity exercise was 0.82. Repeated measures of tau-PCr increase reliability.