Time-resolved Near-infrared Spectroscopy Research Articles

Assessing changes in regional cerebral hemodynamics in adults with a high-density full-head coverage time-resolved near-infrared spectroscopy device.

Cerebral oximeters have the potential to detect abnormal cerebral blood oxygenation to allow for early intervention. However, current commercial systems have two major limitations: (1)spatial coverage of only the frontal region, assuming that surgery-related hemodynamic effects are global and (2)susceptibility to extracerebral signal contamination inherent to continuous-wave near-infrared spectroscopy (NIRS). This work aimed to assess the feasibility of a high-density, time-resolved (tr) NIRS device (Kernel Flow) to monitor regional oxygenation changes across the cerebral cortex during surgery. The Flow system was assessed using two protocols. First, digital carotid compression was applied to healthy volunteers to cause a rapid oxygenation decrease across the ipsilateral hemisphere without affecting the contralateral side. Next, the system was used on patients undergoing shoulder surgery to provide continuous monitoring of cerebral oxygenation. In both protocols, the improved depth sensitivity of trNIRS was investigated by applying moment analysis. A dynamic wavelet filtering approach was also developed to remove observed temperature-induced signal drifts. In the first protocol ( years; five females, five males), hair significantly impacted regional sensitivity; however, the enhanced depth sensitivity of trNIRS was able to separate brain and scalp responses in the frontal region. Regional sensitivity was improved in the clinical study given the age-related reduction in hair density of the patients ( years; 14 females, 13 males). In five patients who received phenylephrine to treat hypotension, different scalp and brain oxygenation responses were apparent, although no regional differences were observed. The Kernel Flow has promise as an intraoperative neuromonitoring device. Although regional sensitivity was affected by hair color and density, enhanced depth sensitivity of trNIRS was able to resolve differences in scalp and brain oxygenation responses in both protocols.

Genetic evidence for involvement of β2-adrenergic receptor in brown adipose tissue thermogenesis in humans.

Sympathetic activation of brown adipose tissue (BAT) thermogenesis can ameliorate obesity and related metabolic abnormalities. However, crucial subtypes of the β-adrenergic receptor (AR), as well as effects of its genetic variants on functions of BAT, remains unclear in humans. We conducted association analyses of genes encoding β-ARs and BAT activity in human adults. Single nucleotide polymorphisms (SNPs) in β1-, β2-, and β3-AR genes (ADRB1, ADRB2, and ADRB3) were tested for the association with BAT activity under mild cold exposure (19 °C, 2 h) in 399 healthy Japanese adults. BAT activity was measured using fluorodeoxyglucose-positron emission tomography and computed tomography (FDG-PET/CT). To validate the results, we assessed the effects of SNPs in the two independent populations comprising 277 healthy East Asian adults using near-infrared time-resolved spectroscopy (NIRTRS) or infrared thermography (IRT). Effects of SNPs on physiological responses to intensive cold exposure were tested in 42 healthy Japanese adult males using an artificial climate chamber. We found a significant association between a functional SNP (rs1042718) in ADRB2 and BAT activity assessed with FDG-PET/CT (p < 0.001). This SNP also showed an association with cold-induced thermogenesis in the population subset. Furthermore, the association was replicated in the two other independent populations; BAT activity was evaluated by NIRTRS or IRT (p < 0.05). This SNP did not show associations with oxygen consumption and cold-induced thermogenesis under intensive cold exposure, suggesting the irrelevance of shivering thermogenesis. The SNPs of ADRB1 and ADRB3 were not associated with these BAT-related traits. The present study supports the importance of β2-AR in the sympathetic regulation of BAT thermogenesis in humans. The present collection of DNA samples is the largest to which information on the donor's BAT activity has been assigned and can serve as a reference for further in-depth understanding of human BAT function.

Time-resolved near-infrared spectroscopy in monitoring acute ischemic stroke patients – Case study

Stroke is a leading cause of disability and death worldwide, with acute ischemic stroke (AIS) accounting for the majority of cases. Early and accurate diagnosis of AIS is crucial for improving patient outcomes. Non-invasive monitoring techniques, such as time domain near-infrared spectroscopy (tdNIRS), have shown potential for real-time monitoring of AIS patients at the bedside. However, there is a need for further research to evaluate the effectiveness of tdNIRS in the acute phase of stroke. In this study, we present the results of a case report using tdNIRS to monitor AIS patients without any additional stimulation. The tdNIRS technique allows for non-invasively assessing cerebral oxygenation in absolute units, enabling accurate measurement of changes in oxygenated and deoxygenated hemoglobin concentrations in the brain. Our aim was to determine the feasibility of tdNIRS in monitoring AIS patients.

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

To investigate cerebral blood volume (CBV) in preterm neonates using time-resolved near-infrared spectroscopy. In this prospective observational study, time-resolved near-infrared spectroscopy measurements of CBV using tNIRS-1 were performed in 70 preterm neonates. For measurements, a sensor was placed for a duration of 1 min, followed by four further reapplications of the sensor, overall five measurements. In this study, 70 preterm neonates with a mean ± SD gestational age of 33.4 ± 1.7 weeks and a birthweight of 1931 ± 398 g were included with a postnatal age of 4.7 ± 2.0 days. Altogether, 2383 CBV values were obtained with an overall mean of 1.85 ± 0.30 mL/100 g brain. A total of 95% of the measured CBV values varied in a range from -0.31 to 0.33 from the overall individual mean. Taking the deviation of the mean of each single application for each patient, this range reduced from -0.07 to 0.07. The precision of the measurement defined as within-variation in CBV was 0.24 mL/100 g brain. The overall mean CBV in stable preterm neonates was 1.85 ± 0.30 mL/100 g brain. The within-variation in CBV was 0.24 mL/100 g brain. Based on the precision obtained by our data, CBV of 1.85 ± 0.30 mL/100 g brain may be assumed as normal value for this cohort.

Cerebrovascular reactivity to carbon dioxide tension in newborns: data from combined time-resolved near-infrared spectroscopy and diffuse correlation spectroscopy.

Critically ill newborns are at risk of brain damage from cerebrovascular disturbances. A cerebral hemodynamic monitoring system would have the potential role to guide targeted intervention. To obtain, in a population of newborn infants, simultaneous near-infrared spectroscopy (NIRS)-based estimates of cerebral tissue oxygen saturation () and blood flow during variations of carbon dioxide tension () levels within physiologic values up to moderate permissive hypercapnia, and to examine if the derived estimate of metabolic rate of oxygen would stay constant, during the same variations. We enrolled clinically stable mechanically ventilated newborns at postnatal age without brain abnormalities at ultrasound. and blood flow index were measured using a non-invasive device (BabyLux), which combine time-resolved NIRS and diffuse-correlation spectroscopy. The effect of changes in transcutaneous on , cerebral blood flow (CBF), and cerebral metabolic rate of oxygen index () were estimated. Ten babies were enrolled and three were excluded. Median GA at enrollment was 39 weeks and median weight 2720 g. increased 0.58% (95% CI 0.55; 0.61, ), CBF 2% (1.9; 2.3, ), and 0.3% (0.05; 0.46, ) per mmHg increase in . BabyLux device detected -induced changes in cerebral and CBF, as expected. The small statistically significant positive relationship between and variation is not considered clinically relevant and we are inclined to consider it as an artifact.

Dissociated coupling between cerebral oxygen metabolism and perfusion in the prefrontal cortex during exercise: a NIRS study.

Purpose: The present study used near-infrared spectroscopy to investigate the relationships between cerebral oxygen metabolism and perfusion in the prefrontal cortex (PFC) during exercises of different intensities. Methods: A total of 12 recreationally active men (age 24 ± 6years) were enrolled. They performed 17min of low-intensity exercise (ExL), followed by 3min of moderate-intensity exercise (ExM) at constant loads. Exercise intensities for ExL and ExM corresponded to 30% and 45% of the participants' heart rate reserve, respectively. Cardiovascular and respiratory parameters were measured. We used near-infrared time-resolved spectroscopy (TRS) to measure the cerebral hemoglobin oxygen saturation (ScO2) and total hemoglobin concentration ([HbT]), which can indicate the cerebral blood volume (CBV). As the cerebral metabolic rate for oxygen (CMRO2) is calculated using cerebral blood flow (CBF) and ScO2, we assumed a constant power law relationship between CBF and CBV based on investigations by positron emission tomography (PET). We estimated the relative changes in CMRO2 (rCMRO2) and CBV (rCBV) from the baseline. During ExL and ExM, the rate of perceived exertion was monitored, and alterations in the subjects' mood induced by exercise were evaluated using the Profile of Moods Scale-Brief. Results: Three minutes after exercise initiation, ScO2 decreased and rCMRO2 surpassed rCBV in the left PFC. When ExL changed to ExM, cardiovascular variables and the sense of effort increased concomitantly with an increase in [HbT] but not in ScO2, and the relationship between rCMRO2 and rCBV was dissociated in both sides of the PFC. Immediately after ExM, [HbT], and ScO2 increased, and the disassociation between rCMRO2 and rCBV was prominent in both sides of the PFC. While blood pressure decreased and a negative mood state was less prominent following ExM compared with that at rest, ScO2 decreased 15min after exercise and rCMRO2 surpassed rCBV in the left PFC. Conclusion: Dissociated coupling between cerebral oxidative metabolism and perfusion in the PFC was consistent with the effort required for increased exercise intensity and associated with post-exercise hypotension and altered mood status after exercise. Our result demonstrates the first preliminary results dealing with the coupling between cerebral oxidative metabolism and perfusion in the PFC using TRS.

Dynamical mass of the white dwarf in XY Ari: a test for intermediate polar X-ray spectral models

ABSTRACT We present a dynamical study of the eclipsing intermediate polar XY Ari based on time-resolved near-infrared spectroscopy obtained with the EMIR spectrograph on the 10.4-m Gran Telescopio Canarias. Using main sequence template spectra taken with the same instrument setup as the target spectra, we measure a radial velocity amplitude of the late K- type donor star K2 = 256 ± 2 km s−1. We also obtain the rotational broadening of its photospheric lines vrot sin i = 141 ± 3 km s−1. From these and the eclipse geometry, we derive a donor-to-white dwarf mass ratio q = M2/M1 = 0.62 ± 0.02, an orbital inclination i = 80.8° ± 0.5° and dynamical masses $M_{1} = 1.21 \pm 0.04 \, \mathrm{M}_{\odot }$ and $M_2 = 0.75 \pm 0.04 \, \mathrm{M}_{\odot }$ (1σ). This result places the white dwarf in XY Ari as one of the three most massive known in a cataclysmic variable. Comparison with white dwarf mass estimates from X-ray spectral studies could indicate the necessity of an improvement of the X-ray models and/or analysis techniques, as a number of X-ray white dwarf masses are in disagreement with the dynamical mass value.

Prefrontal oxygenation is quantified with time-resolved near-infrared spectroscopy: Effect of sex on baseline oxygenation and the response during exercise.

Using time-resolved near-infrared spectroscopy that enables quantitative analysis of optical properties and oxygenation in cerebral tissues and thereby subject-to-subject comparisons in the variables, this study examined the influence of sex on baseline optical properties and oxygenation in the prefrontal cortex (PFC) and the responses during cycling exercise. Absolute levels of oxygenated- and deoxygenated-hemoglobin concentration (Oxy-Hb and Deoxy-Hb) in bilateral PFC were measured at rest and during unilateral cycling at low- and moderate-intensity in young participants (8 women and 10 men). Unilateral cycling was utilized to evaluate no lateralization of the prefrontal oxygenation responses during exercise. Baseline optical properties of bilateral PFC, defined optical pathlength and reduced scattering coefficient, and their responses during cycling were not different between the sexes. Baseline absolute Oxy-Hb of bilateral PFC was significantly lower in women (37 ± 3 μM) than in men (47 ± 7 μM), whereas absolute Deoxy-Hb revealed no sex-related difference. The absolute Oxy-Hb levels in bilateral PFC during low- and moderate-intensity cycling were also lower in women. However, no sex difference was observed when using changes against the baseline levels to normalize baseline differences. No laterality-related differences were observed in the changes in prefrontal Oxy-Hb and Deoxy-Hb during unilateral cycling. Ascertaining no sex-related difference in optical properties of the PFC, the current findings suggest that baseline absolute level of oxygenation in the PFC is lower in women than in men, likely due to lower oxygen supply rather than higher oxygen utilization, and that prefrontal oxygenation responds similarly during exercise independently of sex.

A CMOS Lock-In Pixel Image Sensor With Multisimultaneous Gate for Time-Resolved Near-Infrared Spectroscopy

This article proposes a CMOS lock-in pixel image sensor aiming for time-resolved near-infrared spectroscopy (TR-NIRS). The pixel employs lateral electric field charge modulation (LEFM) with an eight-tap multisimultaneous gate structure and negative substrate bias. The optimization of pixel structure creates a high potential slope with no barrier to facilitate the high-speed photo-generated charge transfer required in the time-resolved application. The sensor employs a two-stage charge transfer architecture with pinned storage diodes (SDs). The effectiveness of the sensor is demonstrated through simulations and experimental measurements. A prototype sensor with 70 (V) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times110$ </tex-math></inline-formula> (H) effective pixels to characterize the multisimultaneous gate lock-in pixel is implemented in a 0.11- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> 1-poly-4-metal CMOS image sensor (CIS) technology. A fast intrinsic response of 240 ps is achieved using an 80-ps pulsewidth 780-nm laser diode by the characterization using two simultaneous gates and a single time window of the lock-in pixel. Performance evaluation using silicon phantoms and further measurement with a rat demonstrates the feasibility of the proposed sensor and setup for TR-NIRS applications.

Fast estimation of adult cerebral blood content and oxygenation with hyperspectral time-resolved near-infrared spectroscopy.

Near-infrared spectroscopy (NIRS) can measure tissue blood content and oxygenation; however, its use for adult neuromonitoring is challenging due to significant contamination from their thick extracerebral layers (ECL; primarily scalp and skull). This report presents a fast method for accurate estimation of adult cerebral blood content and oxygenation from hyperspectral time resolved NIRS (trNIRS) data. A two-phase fitting method, based on a two-layer head model (ECL and brain), was developed. Phase 1 uses spectral constraints to accurately estimate the baseline blood content and oxygenation in both layers, which are then used by Phase 2 to correct for the ECL contamination of the late-arriving photons. The method was validated with in silico data from Monte-Carlo simulations of hyperspectral trNIRS in a realistic model of the adult head obtained from a high-resolution MRI. Phase 1 recovered cerebral blood oxygenation and total hemoglobin with an accuracy of 2.7 ± 2.5 and 2.8 ± 1.8%, respectively, with unknown ECL thickness, and 1.5 ± 1.4 and 1.7 ± 1.1% when the ECL thickness was known. Phase 2 recovered these parameters with an accuracy of 1.5 ± 1.5 and 3.1 ± 0.9%, respectively. Future work will include further validation in tissue-mimicking phantoms with various top layer thicknesses and in a pig model of the adult head before human applications.

Impact of hydrogen gas inhalation during therapeutic hypothermia on cerebral hemodynamics and oxygenation in the asphyxiated piglet

We previously reported the neuroprotective potential of combined hydrogen (H2) gas ventilation therapy and therapeutic hypothermia (TH) by assessing the short-term neurological outcomes and histological findings of 5-day neonatal hypoxic-ischemic (HI) encephalopathy piglets. However, the effects of H2 gas on cerebral circulation and oxygen metabolism and on prognosis were unknown. Here, we used near-infrared time-resolved spectroscopy to compare combined H2 gas ventilation and TH with TH alone. Piglets were divided into three groups: HI insult with normothermia (NT, n = 10), HI insult with hypothermia (TH, 33.5 ± 0.5 °C, n = 8), and HI insult with hypothermia plus H2 ventilation (TH + H2, 2.1–2.7%, n = 8). H2 ventilation and TH were administered and the cerebral blood volume (CBV) and cerebral hemoglobin oxygen saturation (ScO2) were recorded for 24 h after the insult. CBV was significantly higher at 24 h after the insult in the TH + H2 group than in the other groups. ScO2 was significantly lower throughout the 24 h after the insult in the TH + H2 group than in the NT group. In conclusion, combined H2 gas ventilation and TH increased CBV and decreased ScO2, which may reflect elevated cerebral blood flow to meet greater oxygen demand for the surviving neurons, compared with TH alone.

Physiological and Psychological Responses of Viewing a Waterfall Image: A Crossover Study

Growing interest in the relaxation effect of nature has elicited demands for scientific verification of the various natural elements. This study investigated the physiological and psychological responses of 27 females in their 20 s to viewing a waterfall and urban images (control) presented via a large, high-resolution display for 90 s. High-frequency [HF] for parasympathetic nervous activity and the ratio of low-frequency (LF)/[LF + HF] for sympathetic nervous activity by heart rate variability and heart rate were recorded. Simultaneous changes in oxyhemoglobin concentration in the prefrontal cortex were recorded by near-infrared time-resolved spectroscopy. The modified semantic differential method and Profile of Mood States Second Edition were used to assess the psychological effects on the participants after viewing each image. The results showed that viewing the waterfall image, compared with viewing the urban image, (1) increased sympathetic nervous activity; (2) provided comfortable, relaxed, and natural impressions; (3) improved mood states. In conclusion, visual contact with a waterfall image physiologically activated sympathetic nervous activity and psychologically evoked positive moods and feelings.

A Thermally Activated Delayed Fluorescence Emitter Investigated by Time-Resolved Near-Infrared Spectroscopy.

Emitters for organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) require small singlet (S1 )-triplet (T1 ) energy gaps as well as fast intersystem crossing (ISC) transitions. These transitions can be mediated by vibronic mixing with higher excited states Sn and Tn (n=2, 3, 4, …). For a prototypical TADF emitter consisting of a triarylamine and a dicyanobenzene moiety (TAA-DCN) it is shown that these higher states can be located energetically by time-resolved near-infrared (NIR) spectroscopy.

The Acute Effects of a Single Dose of Molecular Hydrogen Supplements on Responses to Ergogenic Adjustments during High-Intensity Intermittent Exercise in Humans.

This research examined the effects of single-dose molecular hydrogen (H2) supplements on acid-base status and local muscle deoxygenation during rest, high-intensity intermittent training (HIIT) performance, and recovery. Ten healthy, trained subjects in a randomized, double-blind, crossover design received H2-rich calcium powder (HCP) (1500 mg, containing 2.544 μg of H2) or H2-depleted placebo (1500 mg) supplements 1 h pre-exercise. They performed six bouts of 7 s all-out pedaling (HIIT) at 7.5% of body weight separated by 40 s pedaling intervals, followed by a recovery period. Blood gases’ pH, PCO2, and HCO3− concentrations were measured at rest. Muscle deoxygenation (deoxy[Hb + Mb]) and tissue O2 saturation (StO2) were determined via time-resolved near-infrared spectroscopy in the vastus lateralis (VL) and rectus femoris (RF) muscles from rest to recovery. At rest, the HCP group had significantly higher PCO2 and HCO3− concentrations and a slight tendency toward acidosis. During exercise, the first HIIT bout’s peak power was significantly higher in HCP (839 ± 112 W) vs. Placebo (816 ± 108 W, p = 0.001), and HCP had a notable effect on significantly increased deoxy[Hb + Mb] concentration during HIIT exercise, despite no differences in heart rate response. The HCP group showed significantly greater O2 extraction in VL and microvascular (Hb) volume in RF during HIIT exercise. The HIIT exercise provided significantly improved blood flow and muscle reoxygenation rates in both the RF and VL during passive recovery compared to rest in all groups. The HCP supplement might exert ergogenic effects on high-intensity exercise and prove advantageous for improving anaerobic HIIT exercise performance.

Physiological and Psychological Benefits of Viewing an Autumn Foliage Mountain Landscape Image among Young Women

Empirically, viewing nature landscapes, including mountains, can promote relaxation. This study aimed to examine the physiological and psychological effects of visual stimulation using an autumn foliage mountain landscape image on autonomic nervous and brain activities. We included 27 female university students who viewed mountain and city (control) landscape images displayed on a large, high-resolution display for 90 seconds. As an indicator of autonomic nervous activity, heart rate variability (high frequency [HF], reflecting parasympathetic nervous activity, and low frequency/high frequency [LF/HF], reflecting sympathetic nervous activity) and heart rate were recorded. Simultaneously, as an indicator of brain activity, oxyhemoglobin concentrations in the prefrontal cortex were assessed using near-infrared time-resolved spectroscopy. Viewing the mountain landscape image significantly increased HF, indicating increased parasympathetic nervous activity. Furthermore, the visual stimulation using the mountain image induced comfortable, relaxed, and natural feelings, as well as improved mood states. In conclusion, viewing an autumn foliage mountain landscape image via large display induced physiological and psychological relaxation in women in their 20s.

The Effects of 10-Week Strength Training in the Winter on Brown-like Adipose Tissue Vascular Density.

There is no evidence of the effect of exercise training on human brown-like adipose tissue vascular density (BAT-d). Here, we report whether whole-body strength training (ST) in a cold environment increased BAT-d. The participants were 18 men aged 20–31 years. They were randomly assigned to two groups: one that performed ST twice a week at 75% intensity of one-repetition maximum for 10 weeks during winter (EX; n = 9) and a control group that did not perform ST (CT; n = 9). The total hemoglobin concentration in the supraclavicular region determined by time-resolved near-infrared spectroscopy was used as a parameter of BAT-d. ST volume (Tvol) was defined as the mean of the weight × repetition × sets of seven training movements. The number of occasions where the room temperature was lower than the median (NRcold) was counted as an index of potential cold exposure during ST. There was no significant between-group difference in BAT-d. Multiple regression analysis using body mass index, body fat percentage, NRcold, and Tvol as independent variables revealed that NRcold and Tvol were determined as predictive of changes in BAT-d. An appropriate combination of ST with cold environments could be an effective strategy for modulating BAT.

Cerebral hemodynamic response during the resuscitation period after hypoxic-ischemic insult predicts brain injury on day 5 after insult in newborn piglets

Perinatal hypoxic-ischemic brain injury of neonates remains a significant problem worldwide. During the resuscitation period, changes in cerebral hemoglobin oxygen saturation (ScO2) have been identified by near-infrared spectroscopy (NIRS). However, in asphyxiated neonates, the relationship between these changes and brain injury is not known. Three-wavelength near-infrared time-resolved spectroscopy, an advanced technology for NIRS, allows for the estimation of ScO2 and cerebral blood volume (CBV). Here, we studied changes in ScO2 and CBV during the resuscitation period after hypoxic-ischemic insult and the relationship between these changes after insult and histopathological brain injuries on day 5 after insult using an asphyxiated piglet model. Of 36 newborn piglets subjected to hypoxic-ischemic insult, 29 were analyzed. ScO2 and CBV were measured 0, 5, 10, 15, and 30 min after the insult. Brain tissue was histologically evaluated on day 5. ScO2 and CBV increased immediately after the insult, reached a peak, and then maintained a consistent value. The increase in CBV 5 to 30 min after the insult was significantly correlated with histopathological injury scores. However, there was no correlation with ScO2. In conclusion, an increase in CBV within 30 min after hypoxic-ischemic insult reflects the histopathological brain injury on day 5 after insult in a piglet model.

Graded Compression Garments Worn During Resistance Exercise: Impact on Muscle Damage, Fatigue, and Oxygenation in Untrained Individuals

Background: Use of compression garments during and after exercise has gained notable popularity, yet their utility in augmenting performance and recovery from resistance exercise remains elusive. Objective: The purpose of this study was to evaluate the effects of wearing compression garments during resistance exercise on exercise-induced muscle damage (EIMD), muscle fatigue and muscle oxygenation. Methods: Ten healthy, untrained individuals (8 females, 2 males, 22.10 ± 2.23 years, 159.09 ± 3.47 cm, 66.22 ±15.93 kg; mean ± SD) performed two exercise trials in a randomized crossover (within-subject) design: 1) with compression garments worn on the legs and 2) without compression. Exercise trials were randomized and separated by seven days. Participants performed 12 sets of 10 maximal repetitions of knee extension, at a velocity of 120 degrees per second, in the CON/ECC mode of a HUMAC NORM isokinetic dynamometer. Muscle oxygenation of the vastus medialis oblique was assessed using time-resolved near-infrared spectroscopy (TRS-21, Hamamatsu). Leg circumference, ratings of perceived muscle soreness (RPMS) and blood samples for creatine kinase (CK) were collected before, immediately after, and 24, 48 and 72 hours after exercise. Results: Total hemoglobin (p = 0.021) and deoxyhemoglobin (p 0.001) were significantly reduced by 8.6% and 9.2% respectively with compression compared to control. No significant differences were found in oxyhemoglobin, oxygen saturation, muscle fatigue, leg circumference, RPMS and CK (p = 0.0791) between conditions. Conclusions: Although lower body compression worn during resistance exercise reduced total hemoglobin and deoxyhemoglobin, there was no impact on muscle fatigue, RPMS, leg circumference or CK.

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

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 (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; 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 O2peak (Ex80%), respectively, on a rowing ergometer, followed by three sessions of 1-min supramaximal exercise (ExSp). After a warm-up at 60% of 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 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.

Near-Infrared Time-Resolved Spectroscopy Shows Anterior Prefrontal Blood Volume Reduction in Schizophrenia but Not in Major Depressive Disorder.

Previous studies using various brain imaging methods have reported prefrontal blood flow disturbances in psychiatric disorders, including schizophrenia and major depressive disorder. In both disorders, alterations of the resting blood flow, in addition to that of the activation in response to task load, have been shown, but the results are not consistent. The present study aimed to examine the anterior prefrontal hemoglobin concentration at the resting state in schizophrenia and depression using near-infrared time-resolved spectroscopy (NIR-TRS), which estimates the optical absorption coefficients and calculates the absolute concentrations of oxygenated (oxy-Hb), deoxygenated (deoxy-Hb), and total (total-Hb; sum of oxy-Hb and deoxy-Hb) hemoglobin. Their ratios to systemic blood hemoglobin concentration (blood-Hb) were also assessed. In agreement with our previous data, total-Hb and total-Hb/blood-Hb in schizophrenia were significantly lower. The present study further revealed that both oxy-Hb/blood-Hb and deoxy-Hb/blood-Hb in schizophrenia were reduced. In depression, total-Hb, total-Hb/blood-Hb, oxy-Hb, and oxy-Hb/blood-Hb were higher than in schizophrenia and were not different from the control. The oxygen saturation (oxy-Hb/total-Hb), in addition to the optical pathlengths, did not show group differences. Lowered oxy-Hb/blood-Hb and deoxy-Hb/blood-Hb together with unchanged oxygen saturation may indicate that the prefrontal blood volume is reduced in schizophrenia. The present findings suggest that NIR-TRS is useful in analyzing the hemodynamic aspects of prefrontal dysfunction in schizophrenia and differentiating schizophrenia from depression.