Nonuniform quadriceps O-2 consumption revealed by near infrared multipointmeasurements

Single location muscle monitoring does not reflect the heterogeneous activa tion of the muscle group(s) during a given exercise. Vastus lateralis and r ectus femoris O-2 consumption (VO2) was investigated, noninvasively, at res t and during maximal voluntary contractions (MVC) using a 12-channel near-i nfrared continuous wave spectroscopy (NIRcws) system (0.1 s acquisition tim e). VO2 either at rest or during MVC was found to be nonuniform in the 11 o ut of 12 measurement sites over a surface of 8 x 8 cm(2). As expected, VO2 during exercise was significantly higher than VO2 at rest (P < 0.01). Howev er, at each muscle measurement site no difference was found between the mea n values (n = 12) Of VO2 measured during a 5-s intermittent MVC and the VO2 values measured during 30-s continuous MVC (P = 0.25). These results stren gthen the role of NIRcws as a powerful tool for investigating the spatial a nd temporal features of muscle oxygenation changes as well as muscle VO2. ( C) 2001 Academic Press.