VO2 slow component correlates with vastus lateralis de-oxygenation and blood lactate accumulation during running

Background. In the present study, vastus lateralis de-oxygenation was monitored contemporarily with (V) over dot O-2 changes along a severe constant intensity running exercise, after the 3(rd) min up to volitional exhaustion. Blood lactate accumulation was also measured before, during and after running. Methods. Eleven male amateur soccer players volunteered for the study. Subjects mean age, height, and body weight NN ere 22.9 +/-2 yrs, 177.5 +/-6.2 cm, 71.7 +/-4 kg, respectively. Measurements were carried out during running on a treadmill. Ventilatory and gas exchange parameters were measured at the mouth on a breath-by-breath basis. For blood lactate concentration accumulation measurement, capillary blood samples were taken from the fingertip. The oxygenation of the vastus lateralis muscle were measured by a continuous wave NIRS portable instrument. By means of two pretests the onset of [La](b) accumulation and its associated velocity (vOBLA), and the peak of oxygen uptake and its associated velocity (v(V) over dot O-2,O-peak) were assessed. The test consisted of running on the treadmill up to volitional exhaustion at a constant velocity corresponding to vOBLA plus 50% of the difference between v(V) over dot O-2,(peak) and vOBLA (v50%Delta). Results. The principal finding of this study was that vastus lateralis de-oxygenation changes measured during running correlate with a) oxygen uptake changes between the 3(rd) min of exercise and the time corresponding to the subject's volitional exhaustion; b) blood lactate concentration increments measured at the 3(rd) and the 6(th) min of exercise and at the time corresponding to the subject's volitional exhaustion. Conclusions. In conclusion, the results of the present study support our hypothesis that the vastus lateralis de-oxygenation contributes consistently to the (V) over dot O-2 slow component development in running.