Influence of the Treadmill Speed/Slope on Quadriceps Oxygenation during dynamic Exercise

One of the main obstacles that has restricted “in vivo” studies of skeletal muscle metabolism during exercise has been the invasive nature of tissue biopsy and the high cost of phosphorus nuclear magnetic resonance equipment. Big research efforts have been recently focused on the development of non-invasive optical techniques to monitor tissue functions. Changes of cerebral and muscle oxy- and deoxy-hemoglobin ([Hb02], [Hb]) can be quantitated from near infrared spectroscopy (NIRS) measurements combining absorption and optical pathlength (Ferrari et al. 1992). NIRS has been extensively used in neuroscience to measure cerebral oxygenation, blood flow, and blood volume (Edwards et al. 1988; Wyatt et al. 1990). Some efforts have been focused also on skeletal muscle. In the last four years the aim of our group has been to explore NIRS capabilities for muscle functional monitoring. Pathlength changes in muscle have been measured on volunteers in different experimental conditions by time resolved spectroscopy (Ferrari et al. 1993) and phase modulation (Duncan et al. 1993). Muscle oxygen consumption (V02) can be measured by NIRS at rest and during isometric exercise by the application of arterial occlusion (Cheatle et al. 1991; De Blasi et al. 1993). We recently proposed a new method for the simultaneous measurement of forearm blood flow and V02 by inducing a venous occlusion (De Blasi et al. 1994)