We use near infrared spectroscopy (NIRS) for the non-invasive assessment of calf oxygenation during a new walking
protocol in healthy subjects of different fitness levels. The protocol increases the exercise power by an increase of the
skew rather than speed, and the incremental power steps are intermitted by a 30 s rest which serves for blood sampling.
The NIRS measurement parameter of tissue oxygenation are discussed, and a high correlation of the oxygen saturation
(tissue oxygenation index) difference between exercise and rest period with exercise power is observed. This difference
parameter can be interpreted as strongly linked to blood flow rather than oxygenation. This finding is supported by
comparison with spirometry data. The effect of training is discussed. The exercise protocol is suited for testing unfit, or
older subjects and the data discussed here servers as a test for a larger trial with heart clinic patients.