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

Abstract

PurposeThis 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 (V.O2peak) on cerebral oxygenation.MethodsEleven 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; V.O2peak, 53.5 ± 6.5 mL min–1 kg–1] rowed a 13-min session separated by 10 and 3 min, at 70 (Ex70%) and 80% of V.O2peak (Ex80%), respectively, on a rowing ergometer, followed by three sessions of 1-min supramaximal exercise (ExSp). After a warm-up at 60% of V.O2peak (ExM), seven male rowers performed a 2,000 m all-out test (Ex2000). Cardiovascular and respiratory variables were measured. Cerebral oxygenation was investigated by near-infrared time-resolved spectroscopy (TRS) to measure cerebral hemoglobin oxygen saturation (ScO2) and total hemoglobin concentration ([HbT]) in the prefrontal cortex (PFC) quantitatively. We estimated the relative changes from rest in cerebral metabolic rate for oxygen (rCMRO2) using TRS at all intensities. During Ex70% and Ex80%, 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 Ex70% and Ex80%.ResultsWhen exercise intensity changed from Ex70% to Ex80%, the sense of effort increased while ScO2 decreased. [HbT] remained unchanged. After Ex70% and Ex80%, a negative mood state was less prominent compared to rest and was accompanied by increases in both ScO2 and [HbT]. At termination of Ex2000, ScO2 decreased by 23% compared to rest. Changes in ScO2 correlated with V.O2peak only during Ex2000 (r = −0.86; p = 0.01). rCMRO2 did not decrease at any intensities.ConclusionOur 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 ScO2.

Precision and normal values of cerebral blood volume in preterm neonates using time‐resolved near‐infrared spectroscopy

“…tNIRS-1 uses a time-correlated single-photon counting technique for detection. 7 For measurements, three different wavelengths are available as light sources (755, 816 and 850 nm). The emitted pulses of the laser diodes have a repetition of 9 MHz for each wavelength.…”

“…The photons reach a depth of several centimetres with a passing through of the scalp, skull and frontal lobe. 7 Details of methodology has already been described elsewhere. 7,9 The absorption coefficients are used to determine the concentration of oxygenated haemoglobin and deoxygenated haemoglobin.…”

“…7 Details of methodology has already been described elsewhere. 7,9 The absorption coefficients are used to determine the concentration of oxygenated haemoglobin and deoxygenated haemoglobin. 9,14 Out of oxygenated and deoxygenated haemoglobin, Hb tot can be calculated by the following equation 9 : Time-resolved NIRS measurements enables absolute values of CBV.…”

“…It can be calculated by using the Hb tot , the factor 0.89, representing the cerebral-to-large vessel haematocrit ratio and the concentration of haemoglobin in the blood 7,9,15,16 using the equation:…”

“…In several studies 1,3,6 ∆CBV was measured by NIRS using spatially resolved technique; however, only a few publications exist using time-resolved NIRS technique. 7,8 ∆CBV can be calculated, in proportion to Hb tot concentrations, under the assumption of a constant haemoglobin (Hb) and cerebral-to-large vessel haematocrit ratio. 1 Studies have already described the importance of reproducibility of measurements of cerebral haemodynamics using NIRS.…”