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Gait speed declines with age and slower walking speeds are associated with poor health outcomes. Understanding why we do not walk faster as we age, despite being able to, has implications for rehabilitation. Changes in regional oxygenated haemoglobin (HbO2) across the frontal lobe were monitored using functional near infrared spectroscopy in 17 young and 18 older adults while they walked on a treadmill for 5 min, alternating between 30 s of walking at a preferred and fast (120% preferred) speed. Gait was quantified using a triaxial accelerometer (lower back). Differences between task (preferred/fast) and group (young/old) and associations between regional HbO2 and gait were evaluated. Paired tests indicated increased HbO2 in the supplementary motor area (right) and primary motor cortex (left and right) in older adults when walking fast (p < 0.006). HbO2 did not significantly change in the young when walking fast, despite both groups modulating gait. When evaluating the effect of age (linear mixed effects model), greater increases in HbO2 were observed for older adults when walking fast (prefrontal cortex, premotor cortex, supplementary motor area and primary motor cortex) compared to young adults. In older adults, increased step length and reduced step length variability were associated with larger increases in HbO2 across multiple regions when walking fast. Walking fast required increased activation of motor regions in older adults, which may serve as a therapeutic target for rehabilitation. Widespread increases in HbO2 across the frontal cortex highlight that walking fast represents a resource-intensive task as we age. [ABSTRACT FROM AUTHOR]

Gait speed declines with age and slower walking speeds are associated with poor health outcomes. Understanding why we do not walk faster as we age, despite being able to, has implications for rehabilitation. Changes in regional oxygenated haemoglobin (HbO2) across the frontal lobe were monitored using functional near infrared spectroscopy in 17 young and 18 older adults while they walked on a treadmill for 5 min, alternating between 30 s of walking at a preferred and fast (120% preferred) speed. Gait was quantified using a triaxial accelerometer (lower back). Differences between task (preferred/fast) and group (young/old) and associations between regional HbO2 and gait were evaluated. Paired tests indicated increased HbO2 in the supplementary motor area (right) and primary motor cortex (left and right) in older adults when walking fast (p < 0.006). HbO2 did not significantly change in the young when walking fast, despite both groups modulating gait. When evaluating the effect of age (linear mixed effects model), greater increases in HbO2 were observed for older adults when walking fast (prefrontal cortex, premotor cortex, supplementary motor area and primary motor cortex) compared to young adults. In older adults, increased step length and reduced step length variability were associated with larger increases in HbO2 across multiple regions when walking fast. Walking fast required increased activation of motor regions in older adults, which may serve as a therapeutic target for rehabilitation. Widespread increases in HbO2 across the frontal cortex highlight that walking fast represents a resource-intensive task as we age.

The purpose of this study was to compare the temporal increase in muscle cross-sectional area (CSA) as the acute response of resistance exercise (RE) between resistance-trained and untrained groups and investigate the factors that affect the muscle CSA. Resistance-trained (n = 14) and untrained (n = 14) subjects performed four kinds of triceps brachii RE. Muscle CSA and intracellular hydration (IH), were measured prior to and 5-, 30-, and 60-minute after RE. Pearson's correlation coefficient was calculated to clarify the relationships among percent increases in muscle CSA and IH, area under the Oyx-Hb curve, blood lactate concentration, and % maximum voluntary contraction (MVC)-root-mean-square (RMS) of electromyogram (EMG). At 5-minute after RE, muscle CSA increased significantly to 120.2 ± 6.3% in the resistance-trained group and 105.5 ± 2.3% in the untrained group (p < .01). However, neither group showed a significant difference between the values before and 30-minute after RE. In the resistance-trained group, there was a significant increase in IH at 5-minute post-RH (p < .01), and correlations were found between percent increases in muscle CSA and IH (r = 0.70, p < .01), area under the Oxy-Hb curve (r = 0.77, p < .01), and % MVC-RMS of EMG (r = 0.72, p < .01). The findings of this study suggest that measurements of muscle CSA in studies of muscle hypertrophy should be performed 30-minute or more after the last resistance exercise session, and muscle pump exercises should be conducted just before participation in bodybuilding, and physique contests.

To better understand the neural mechanisms behind the effect of intermittent theta-burst stimulation (iTBS), we investigated how the prefrontal blood oxygenation response measured by changes in oxygenated haemoglobin (oxy-Hb) was modulated during a sham-controlled iTBS treatment course, and whether this was related to depressive symptom change. In this randomised, double-blind study, patients with ongoing treatment-resistant depression received either active (n = 18) or sham (n = 21) iTBS over the dorsomedial prefrontal cortex for ten to fifteen days with two sessions daily. Event-related functional near-infrared spectroscopy (fNIRS) was measured during each iTBS train, and resting-state oxy-Hb was compared before and after each iTBS session at the first, fifth, and last treatment day. Patients receiving active iTBS had an increase of the event-related oxy-Hb response compared to the sham group on the fifth (bilateral prefrontal cortices p <.001) and last (left prefrontal p =.007, right prefrontal p =.025) treatment day. Resting-state analysis showed suppressed oxy-Hb change in active iTBS compared to sham iTBS on the last treatment day (p =.024). Oxy-Hb change was unrelated to depressive symptom change (p =.474). This study describes a modulation of the blood oxygenation response over the prefrontal cortex that was built up during the course of active iTBS treatment in depression. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the temporal increase in muscle cross-sectional area (CSA) as the acute response of resistance exercise (RE) between resistance-trained and untrained groups and investigate the factors that affect the muscle CSA. Resistance-trained (n = 14) and untrained (n = 14) subjects performed four kinds of triceps brachii RE. Muscle CSA and intracellular hydration (IH), were measured prior to and 5-, 30-, and 60-minute after RE. Pearson's correlation coefficient was calculated to clarify the relationships among percent increases in muscle CSA and IH, area under the Oyx-Hb curve, blood lactate concentration, and % maximum voluntary contraction (MVC)-rootmean- square (RMS) of electromyogram (EMG). At 5-minute after RE, muscle CSA increased significantly to 120.2 ± 6.3% in the resistance-trained group and 105.5 ± 2.3% in the untrained group (p < .01). However, neither group showed a significant difference between the values before and 30-minute after RE. In the resistance-trained group, there was a significant increase in IH at 5-minute post-RH (p < .01), and correlations were found between percent increases in muscle CSA and IH (r = 0.70, p < .01), area under the Oxy-Hb curve (r = 0.77, p < .01), and % MVC-RMS of EMG (r = 0.72, p < .01). The findings of this study suggest that measurements of muscle CSA in studies of muscle hypertrophy should be performed 30-minute or more after the last resistance exercise session, and muscle pump exercises should be conducted just before participation in bodybuilding, and physique contests. [ABSTRACT FROM AUTHOR]

This study aimed to determine whether changes in initial restrictive pressures ( IRP, tightness of the cuff before inflation with air) affect tissue oxygenation, lactate production and leg strength before, during and after knee extension exercises. The cuff was positioned on the right thigh, and the IRP of either 40-45 or 60-65 mmHg were applied randomly prior to inflating the cuff to the final restrictive pressure (the pressure reached after inflating the cuff with air). Subjects performed four sets (30, 15, 15 and 15 reps) of isotonic knee extensions with 1-min rest between sets. Tissue oxygenation and blood lactate levels were assessed prior to, during and after exercise, and leg strength was assessed pre- and postexercise. There were significant condition by time interactions ( P<0·01) and main effects for both condition ( P<0·01) and time ( P<0·01) for tissue oxygenation, deoxyhaemoglobin, total haemoglobin. Significant main effects were detected for both condition ( P<0·01) and time ( P<0·01) for leg strength values. There was only a significant time main effect for lactate concentrations. This study is the first to show that a higher IRP had a significant impact on percent tissue oxygenation, leg strength and deoxygenated haemoglobin accumulation during exercise. [ABSTRACT FROM AUTHOR]

1. The aim of the present study was to examine the effects of inhibition of the Na+/H+ exchanger (NHE-1) on cardiopulmonary performance, oxygen carrying capacity and tissue inflammation in a pig model of traumatic haemorrhage–resuscitation. 2. In 12 instrumented anaesthetized pigs, traumatic haemorrhage was modelled by producing tibia fractures, followed by haemorrhage of 25 mL/kg for 20 min, and then a 4 mm hepatic arterial tear with surgical repair after 20 min. Animals then underwent low-volume fluid resuscitation with either Hextend (vehicle; n = 6; Hospira, Lake Forest, IL, USA) or 3 mg/kg BIIB513 (an NHE-1 inhibitor) + Hextend ( n = 6). The experiment was terminated 6 h after the beginning of resuscitation. 3. Compared with vehicle-treated controls, the addition of NHE-1 inhibition with BIIB513 significantly improved the left ventricle stroke work index and attenuated increases in pulmonary arterial pressure and pulmonary vascular resistance. Furthermore, BIIB513 treatment significantly increased the oxygenated haemoglobin ratio, blood oxygen content and mixed venous blood oxygen saturation and improved blood oxygen delivery. In addition, BIIB513 treatment reduced lung tissue levels of interleukin-6 by 80%, tumour necrosis factor-α by 37% and myeloperoxidase activity by 38%. Nuclear factor-κB DNA binding activity in the lung was also slightly and significantly attenuated following BIIB513 treatment. 4. In conclusion, the present study shows that NHE-1 inhibition facilitates the response to fluid resuscitation after traumatic haemorrhage by improving cardiac function, pulmonary vascular function and oxygen carrying capacity, which results in reduced tissue inflammatory injury. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of the present study was to investigate the retest reliability of event-related functional near-infrared spectroscopy (fNIRS). Therefore, isolated functional activation was evoked in the occipital cortex by a periodic checkerboard stimulation. During a 52-channel fNIRS recording, 12 subjects underwent 60 trials of visual stimulation in two sessions. The retest interval was set to 3 weeks. Linear correlations of the contrast t values supplemented by scatter plots, channel-wise intraclass correlation coefficients (ICC) as well as reproducibility indices for the quantity of activated channels (R QUANTITY) and the location (R OVERLAP) of the detected activation were calculated. The results at the group level showed good reliability in terms of the single measure ICCs (up to 0.84) and excellent reproducibility quantified by R QUANTITY and R OVERLAP (up to 96% of the quantity and the location were reproducible), whereas the results at the single subjects'' level were mediocre. Furthermore, the reliability assessed by single measurement ICCs improved if regarded at a cluster level. [Copyright &y& Elsevier]

Abstract: Near infrared spectroscopy (NIRS) has been successful in monitoring cerebral haemodynamics when the subject is immobilized during surgery, and when there is a drastic depletion of blood from the cerebral cortex during positive acceleration. In this study, we monitored subtle changes of cerebral oxygen level using NIRS during vestibular stimulation. For the control conditions, cerebral oxygen status was monitored in six stationary subjects sitting upright, and while they executed head movements in the pitch axis with eyes opened and eyes closed. The experimental conditions involved the subjects making a head movement which required a 45° pitch-down followed by a return to upright head movements 12s later during yaw rotation (Coriolis cross coupling) at 10 and 20 rotations per minute (rpm) in a random order. Oxyhaemoglobin (O2Hb), deoxyhaemoglobin (HHb) and total haemoglobin levels were recorded every 0.5s from both the parietal and the occipital lobe simultaneously. A significant rotation effect was observed in total Hb level changes from baseline in both regions. Occipital O2Hb increased significantly after the head movement with eyes opened at 20 rpm. Our findings appear to be consistent with previous vestibular studies that significant changes in brain blood flow occur during caloric stimulation. NIRS can be used to monitor discrete cortical blood flow changes resulting from vestibular and other forms of stimulation. [Copyright &y& Elsevier]

Summary The biochemical features of skeletal muscle and its contribution to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD) is under active investigation. Near-infrared spectroscopy (NIRS) can non-invasively provide information on the oxidative capacity of muscle. To clarify whether oxygenation of peripheral muscle is one determinant of exercise tolerance, we simultaneously examined the oxygen uptake (&formmu1;) kinetics and oxygen kinetics of peripheral skeletal muscle evaluated by NIRS during recovery from exercise in COPD patients. Fifteen patients with COPD and five normal control subjects performed a symptom-limited incremental exercise test. On the following day, all patients performed a constant work rate exercise test while being monitored using NIRS continuously for changes in concentration of oxygenated haemoglobin (Hb[sub O[sub 2] ] ) and during expired gas analysis. We found that the time constant of &formmu2; during recovery from constant work rate exercise (&formmu3;) and the time constant of Hb[sub O[sub 2] ] during recovery (τ Hb[sub O[sub 2off] ] ) were significantly longer in COPD patients than in normal control subjects. &formmu4; was inversely correlated with absolute values of forced expiratory volume in 1 s (FEV[sub 1·0] ) and FEV[sub 1·0] (% predicted). However, no significant correlation was found between &formmu5; and FVC (forced vital capacity), FEV[sub 1·0] /FVC, or diffusing capacity of the lung for CO (DL[sub CO] ). Moreover, &formmu6; was inversely correlated with maximal &formmu7; and maximal work rate. In contrast, &formmu8; exhibited a significant positive correlation with τ Hb[sub O[sub 2off] ] . These results indicate that &formmu9; kinetics during recovery is related to re-oxygenation of peripheral skeletal muscle evaluated by NIRS in patients with COPD. Therefore, NIRS may be a useful tool to estimate the impairment of cardiopulmonary responses and re-oxygenation of peripheral skeletal muscle during the immediate recovery phase after exercise in COPD patients. [ABSTRACT FROM AUTHOR]

Summary Reflectance near-infrared spectroscopy (NIRS) has become a suitable and easily manageable method to monitor cerebral oxygenation changes in presyncopal and syncopal symptoms caused by postural changing or standing. A new clinical tissue oxygenation monitor has been recently developed which measures absolute tissue haemoglobin saturation (Tissue Oxygenation Index, TOI) utilizing spatially resolved spectroscopy (SRS). The present study examined the effects of postural changes on cerebral oxygenation as reflected in SRS-NIRS findings. Cerebral oxyhaemoglobin (O2 Hb), deoxyhaemoglobin (HHb), and the TOI were recorded from both sides of the forehead in five healthy male subjects (age range, 28–40 years) during 90° head-up tilt (HUT) and -6° head-down tilt (HDT). Three series of measurements were carried out on separate days. O2 Hb was decreased during HUT. TOI was significantly lower in HUT than in the supine position (SUP). There was no significant change in TOI during HDT. A significant session effect was observed in the left forehead TOI during SUP, but not in the right. SRS-NIRS measurements confirmed sub-clinical alterations of cortical oxygenation during HUT. NIRS data from the left side of the forehead, which may vary with cognitive or emotional activation, were more variable than those from the right side. [ABSTRACT FROM AUTHOR]

[Purpose] Previous studies have indicated that animal-assisted therapy can promote recovery of psychological, social, and physiological function in mental disorders. This study was designed as a pilot evaluation of the use of near-infrared spectroscopy to objectively identify changes in brain activity that could mediate the effect of animal-assisted therapy. [Subjects and Methods] The participants were 20 healthy students (10 males and 10 females; age 19-21 years) of the Faculty of Agriculture, Saga University. Participants were shown a picture of a Tokara goat or shack (control) while prefrontal cortical oxygenated haemoglobin levels (representing neural activity) were measured by near-infrared spectroscopy. [Results] The prefrontal cortical near-infrared spectroscopy signal was significantly higher during viewing of the animal picture than during a rest condition or during viewing of the control picture. [Conclusion] Our results suggest that near-infrared spectroscopy can be used to objectively identify brain activity changes during human mentation regarding animals; furthermore, these preliminary results suggest the efficacy of animal-assisted therapy could be related to increased activation of the prefrontal cortex.