Figure 1. ³¹P-MRS measures of mitochondrial function.

(A) Representative single spectra (NA = 1) at rest (upper) and near end exercise (lower), with 2 Hz line broadening applied for illustrative purposes. (B) Corresponding PCr timecourse to the spectra in A, which illustrates the typical [PCr] end-exercise depletion in this study. The SNR of this timecourse was 46, significantly below average. The black line represents the monoexponential fit to both PCr recoveries. The recovery time constant, k, was 1.87 min⁻¹ and 1.83 min⁻¹ for recovery from exercise bouts 1 and 2 respectively. (C) Mean fractional PCr recovery curves for physical activity matched ID (grey squares; n = 11) and DS (black circles; n = 10). Five spectra were averaged to give a time resolution of 10 seconds for clarity in this figure. The monoexponential fit using the mean recovery rate constant is shown for ID (grey line) and DS (black line). (D) Recovery rate constant (k) for matched physical activity groups of ID (white bars; n = 11) and for DS (black bars; n = 10). In C–D, data are mean +/− SEM.