Functional Near-Infrared Spectroscopy

fNIRS has previously been used in pregnancy and specifically in GDM, supporting its safety in these conditions. The fNIRS system measures changes in oxyhaemoglobin, deoxyhaemoglobin, and total haemoglobin concentrations. The rationale for including fNIRS is that compromised nervous system function may contribute importantly to sarcopenia. Signal analysis will include advanced variability methods such as fractal dimension, detrended fluctuations, and approximate entropy. fNIRS is offered on a voluntary basis to assess neuronal activity during the handgrip test at visit 2.