Estimation of Cerebral Hemodynamics and Oxygenation During Various Intensities of Rowing Exercise: An NIRS Study.

Purpose: This study aimed to investigate changes in cerebral hemodynamics and oxygenation at moderate, heavy, maximal and supramaximal intensities of rowing exercise. It also examined whether these changes reflect alterations in sensation of effort and mood. We also aimed to examine the effects of peak pulmonary oxygen consumption ( O ) on cerebral oxygenation.

Methods: Eleven rowers, consisting out of six athletes and five recreational rowers [two female; age, 27 ± 9 years; height, 171 ± 7 cm, body mass, 67 ± 9 kg; O , 53.5 ± 6.5 mL min kg] rowed a 13-min session separated by 10 and 3 min, at 70 (Ex) and 80% of O (Ex), respectively, on a rowing ergometer, followed by three sessions of 1-min supramaximal exercise (ExSp). After a warm-up at 60% of O (ExM), seven male rowers performed a 2,000 m all-out test (Ex). Cardiovascular and respiratory variables were measured. Cerebral oxygenation was investigated by near-infrared time-resolved spectroscopy (TRS) to measure cerebral hemoglobin oxygen saturation (ScO) and total hemoglobin concentration ([HbT]) in the prefrontal cortex (PFC) quantitatively. We estimated the relative changes from rest in cerebral metabolic rate for oxygen (rCMRO) using TRS at all intensities. During Ex and Ex, ratings of perceived exertion (RPE) were monitored, and alteration of the subject's mood was evaluated using a questionnaire of Positive-and-Negative-Affect-Schedule after Ex and Ex.

Results: When exercise intensity changed from Ex to Ex, the sense of effort increased while ScO decreased. [HbT] remained unchanged. After Ex and Ex, a negative mood state was less prominent compared to rest and was accompanied by increases in both ScO and [HbT]. At termination of Ex, ScO decreased by 23% compared to rest. Changes in ScO correlated with O only during Ex ( = -0.86; = 0.01). rCMRO did not decrease at any intensities.

Conclusion: Our results suggest that alterations in the sense of effort are associated with oxygenation in the PFC, while positive changes in mood status are associated with cerebral perfusion and oxygen metabolism estimated by TRS. At exhaustion, the cerebral metabolic rate for oxygen is maintained despite a decrease in ScO.