Interleaved BOLD and 31P-MRS examination of working human upper arm muscles

Phosphorous (31P) MRS is frequently used to study alterations in muscle mitochondrial function but works under the assumption that exercise triggers sufficient changes in perfusion to allow for delivery oxygen and energy substrates to the tissue. Here, we used interleaved scanning of 31PMRS and BOLD imaging to obtain an in-debt evaluation of muscle oxidative capacity in the upper arm muscles during arm-cycling exercise. We demonstrated that similar levels of PCr depletion and PCr recovery times resulted in variable Time-To-Peaks (TTPs) and max %BOLD response while a tendency was observed between a lower end-exercise pH and longer TTP.