A new combined deep-body-temperature/NIRs probe for noninvasive metabolic measurements on human skeletal muscle

Temperature modulates tissue metabolism through thermodynamic phenomena, e.g. changes in enzymatic activities, pH variations, etc. In humans, temperature changes may be induced by stressful environmental conditions (e.g. immersion in cold water, etc.) or, artificially, during therapeutic procedures (extracorporeal circulation, cancer treatment using hyperthermia, etc.). Moreover, temperature distribution is not uniform in the body. In a forearm immersed in cold water at 20°C, it is possible to observe radial gradient values reaching 2°C/cm (Ducharme et al., 1991). Thus, the measurement of total tissue metabolism often results from the contribution of several subsets of tissue exposed to different temperatures, making the interpretation of the data sometimes difficult. In this context, the aim of the present study was to develop a non-in-vasive probe allowing one to simultaneously: 1) establish in a human skeletal muscle a region of uniform temperature; 2) measure the temperature; 3) measure the oxidative metabolism in the corresponding region.