The advent of near infrared spectroscopy (NIRS) as a tool for monitoring muscle oxygenation has allowed for important physiological data in sports training and rehabilitation. Commercial methods are generally user-friendly and the technique is non- invasive. By projecting a light beam in to the muscle concentrations of haemoglobin/myoglobin (with and without oxygen) in the vascular bed consisting of small arterioles, capillaries and venules can be determined. Despite its appeal methodological improvements to account for varying muscle depths, and to distinguish between arteriolar and venular contributions separatelyare desired.