The influence of endurance training on brain and leg blood volumes translocation during an orthostatic test

Abstract

The aim of this study was to ascertain whether the redistribution of blood from upper parts towards the lower parts of the body during an orthostatic test was detected by using near infrared spectroscopy (NIRS) measurements. Brain and muscle tissue total hemoglobin concentration (TOTHb) was measured for assessment the displacement of blood during an orthostatic test before and after the 8 weeks of interval running training. For this purpose a NIRS Oxymeter (ISS, Champaign, USA) was used. Two groups: experimental (N=6 subjects, 24±5 years, 177±6 cm, 78±8 kg) and control (N=5 subjects, 25±3 years, 180±5 cm, 82±5 kg) performed initially a incremental walking test on treadmill for assessment of Vo2 peak and competition in uphill walking with additional weight of 15 kg for assessment of endurance performance. The third test was orthostatic test wit a 15 min resting in supine position, following first with 5 min upright, and returning to supine position for another 5 min. Tests were performed before and after training period. The results showed an increase of endurance and Vo2 peak. The brain RTOTHb showed an increase to 1.9±1.3 μmol before training in contrast to decrease from resting values to -2.9±4.4 μmol in the end of training (P<0.01). Differently leg increase of RTOTHb was 30.2±12.8 μmol before training but increased less to a 25.3±11.4 μmol) (P<0.01) after the training. The data suggested that bran was affected by translocation of blood to lower parts of the body, due to endurance training. However, the expected increase of the calf blood volume was not approved.