scholarly journals One-week cocoa flavanol intake increases prefrontal cortex oxygenation at rest and during moderate-intensity exercise in normoxia and hypoxia

2018 ◽  
Vol 125 (1) ◽  
pp. 8-18 ◽  
Author(s):  
Lieselot Decroix ◽  
Cajsa Tonoli ◽  
Elodie Lespagnol ◽  
Constantino Balestra ◽  
Amandine Descat ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Lipid Peroxidation ◽  
Endothelial Function ◽  
Antioxidant Capacity ◽  
Near Infrared ◽  
Tissue Oxygenation ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Double Blind ◽  
Exercise Induced

During exercise in hypoxia, O2 delivery to brain and muscle is compromised, and oxidative stress is elicited. Cocoa flavanols (CF) have antioxidant capacities and can increase blood flow by stimulating endothelial function. We aimed to examine the effects of 7-day CF intake on oxidative stress, nitric oxide production, and tissue oxygenation in response to exercise in normobaric hypoxia (14.3% O2). In a randomized, double-blind, cross-over study, 14 well-trained male cyclists completed four trials: exercise in normoxia or hypoxia, after 7-day CF or placebo intake. Flow-mediated dilation (FMD) was measured before intake of the last dose CF or placebo. One hundred minutes later, 20-min steady-state (SS; 45% V̇o2max) and 20-min time trial (TT) (cycling) were performed. Blood samples were taken. Prefrontal and muscular oxygenation was assessed by near-infrared spectroscopy. At baseline, FMD was increased by CF. Hypoxia increased exercise-induced elevations in lipid peroxidation and antioxidant capacity. CF suppressed exercise-induced lipid peroxidation but did not influence antioxidant capacity. At rest and during SS, prefrontal and muscular oxygenation was decreased by hypoxia. CF elevated prefrontal oxygenation but did not impact muscular oxygenation. During TT, hypoxia accelerated the exercise-induced decrease in prefrontal oxygenation, but not in muscular oxygenation. During TT, CF did not alter prefrontal and muscular oxygenation. CF did not change plasma nitrite, nitrate, and arginine:citrulline. During high-intensity exercise, CF improved neither tissue oxygenation nor performance in well-trained athletes. At rest and during moderate-intensity exercise, CF reduced exercise-induced lipid peroxidation and partially restored the hypoxia-induced decline in prefrontal oxygenation. NEW & NOTEWORTHY For the first time, we showed that CF had beneficial effects on endothelial function at rest, as well as on prefrontal oxygenation at rest and during moderate-intensity exercise, both in normoxia and hypoxia. Moreover, we showed that CF intake inhibited oxidative stress during exhaustive exercise in hypoxia.

scholarly journals Impact of cocoa flavanol consumption on blood pressure responsiveness to exercise

2010 ◽  
Vol 103 (10) ◽  
pp. 1480-1484 ◽  
Author(s):  
Narelle M. Berry ◽  
Kade Davison ◽  
Alison M. Coates ◽  
Jonathan D. Buckley ◽  
Peter R. C. Howe
Keyword(s):  
Blood Pressure ◽  
Analysis Of Covariance ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Double Blind ◽  
Flow Mediated Dilatation ◽  
Dependent Flow ◽  
Exercise Induced ◽  
Response To Exercise ◽  
Cocoa Flavanols

Impaired endothelial vasodilatation may contribute to the exaggerated blood pressure (BP) responses to exercise in individuals who are overweight/obese. The present study investigated whether consumption of cocoa flavanols, which improve endothelium-dependent flow-mediated dilatation (FMD), can modify BP responsiveness to exercise. Twenty-one volunteers (eight females and thirteen males, 54·9 (se2·2) years, BMI 31·6 (se0·8) kg/m2, systolic BP 134 (se2) mmHg, diastolic BP (DBP) 87 (se2) mmHg) were randomised to consume single servings of either a high-flavanol (HF, 701 mg) or a low-flavanol (LF, 22 mg) cocoa beverage in a double-blind, cross-over design with 3–7-d washout between treatments. Two hours after cocoa consumption, FMD was measured, followed by continuous beat-to-beat assessment (Finapres™) of BP before and during 10 min of cycling at 75 % of age-predicted maximum heart rate. Averaged data from two assessments on each type of beverage were compared by analysis of covariance using pre-exercise BP as the covariate. Pre-exercise BP was similar after taking LF and HF (153 (se3)/88 (se3)v. 153 (se4)/87 (se2) mmHg, respectively,P>0·05). However, the BP response to exercise (area under BP curve) was attenuated by HF compared with LF. BP increases were 68 % lower for DBP (P = 0·03) and 14 % lower for mean BP (P = 0·05). FMD measurements were higher after taking HF than after taking LF (6·1 (se0·6) %v. 3·4 (se0·5) %,P < 0·001). By facilitating vasodilation and attenuating exercise-induced increases in BP, cocoa flavanols may decrease cardiovascular risk and enhance the cardiovascular benefits of moderate intensity exercise in at-risk individuals.

Effect of pharmacological lowering of plasma urate on exercise-induced oxidative stress

2007 ◽  
Vol 32 (6) ◽  
pp. 1148-1155 ◽  
Author(s):  
S. R. McAnulty ◽  
P. A. Hosick ◽  
L. S. McAnulty ◽  
J. C. Quindry ◽  
L. Still ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Capacity ◽  
Repeated Measures ◽  
Lipid Hydroperoxides ◽  
Double Blind ◽  
Reducing Ability ◽  
Plasma Antioxidant Capacity ◽  
Plasma Urate ◽  
Exercise Induced ◽  
The Impact

Urate is a metabolic end product of purine metabolism that contributes about 66% of the antioxidant capacity of plasma. The objective of this study was to evaluate the importance of plasma urate as an antioxidant using pharmacological lowering and examining the impact on plasma antioxidant capacity and oxidative stress after intense exercise. Fifteen subjects ran for 45 min at ~80% VO2 max under the influence of probenecid (1 g/d) (PRO) or placebo (PLA) in a double-blind, crossover design. Blood samples obtained at baseline, pre-exercise, and immediately post-exercise were analyzed for F2-isoprostanes, lipid hydroperoxides (LHs), ferric-reducing ability of plasma (FRAP), urate, ascorbate (AA), and nitrite. A 2 (group) × 2 (time) repeated-measures analysis of variance (ANOVA), one-way ANOVA, Tukey–Kramer multiple comparison tests, and Student’s t tests were used for statistical analysis. PRO exhibited lowered urate and FRAP compared with baseline (p ≤ 0.05), and group effects existed for the exercise trials (p = 0.023 and p ≤ 0.001, respectively) versus PLA. F2-isoprostanes, nitrite, and AA were increased after exercise (p = 0.004, p = 0.001, and p = 0.003, respectively), but the pattern of change was not different between treatments. This study indicates that plasma markers of exercise-induced oxidative stress were not affected by below-normal physiological concentrations of urate and a diminished antioxidant capacity within the plasma compartment.

Intermittent hypoxic training: implications for lipid peroxidation induced by acute normoxic exercise in active men

2001 ◽  
Vol 101 (5) ◽  
pp. 465-475 ◽  
Author(s):  
Damian M. BAILEY ◽  
Bruce DAVIES ◽  
Ian S. YOUNG
Keyword(s):  
Oxidative Stress ◽  
Lipid Peroxidation ◽  
Acute Exercise ◽  
Mass Action ◽  
Lipid Hydroperoxides ◽  
Double Blind ◽  
Intermittent Hypoxic Training ◽  
Hypoxic Conditions ◽  
Hypoxic Training ◽  
Exercise Induced

Oxidant generation during regular physical exercise training may influence the adaptive responses that have been shown to confer protection against oxidative stress induced by subsequent acute exercise. To examine this, we randomly assigned 32 males to either a normoxic (n = 14) or a hypoxic (n = 18) group. During the acute phase, subjects in the hypoxic group performed two maximal cycling tests in a randomized double-blind fashion: one under conditions of normoxia and the other under hypoxic conditions (inspired fraction of O2 = 0.21 and 0.16 respectively). During the intermittent phase, the normoxic and hypoxic groups each trained for 4 weeks at the same relative exercise intensity, under conditions of normoxia and hypoxia respectively. During acute exercise under hypoxic conditions, the venous concentrations of lipid hydroperoxides and malondialdehyde were increased, despite a comparatively lower maximal oxygen uptake (o2max) (P < 0.05 compared with normoxia). The increases in lipid hydroperoxides and malondialdehyde were correlated with the exercise-induced decrease in arterial haemoglobin oxygen saturation (r =-0.61 and r =-0.50 respectively; P < 0.05), but not with o2max. Intermittent hypoxic training attenuated the increases in lipid hydroperoxides and malondialdehyde induced by acute normoxic exercise more effectively than did normoxic training, due to a selective mobilization of α-tocopherol (P < 0.05). The latter was related to enhanced exercise-induced mobilization/oxidation of blood lipids due to a selective increase in o2max (P < 0.05 compared with normoxic group). We conclude that lipid peroxidation induced by acute exercise (1) increases during hypoxia; (2) is not regulated exclusively by a mass action effect of o2; and (3) is selectively attenuated by regular hypoxic training. Oxidative stress may thus be considered as a biological prerequisite for adaptation to physical stress in humans.

scholarly journals Beetroot juice supplementation speeds O2uptake kinetics and improves exercise tolerance during severe-intensity exercise initiated from an elevated metabolic rate

2013 ◽  
Vol 305 (12) ◽  
pp. R1441-R1450 ◽  
Author(s):  
Brynmor C. Breese ◽  
Melitta A. McNarry ◽  
Simon Marwood ◽  
Jamie R. Blackwell ◽  
Stephen J. Bailey ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Exercise Tolerance ◽  
Near Infrared ◽  
Order Type ◽  
Moderate Intensity ◽  
Type Ii ◽  
Beetroot Juice ◽  
Moderate Intensity Exercise ◽  
Double Blind ◽  
Severe Intensity

Recent research has suggested that dietary nitrate (NO3−) supplementation might alter the physiological responses to exercise via specific effects on type II muscle. Severe-intensity exercise initiated from an elevated metabolic rate would be expected to enhance the proportional activation of higher-order (type II) muscle fibers. The purpose of this study was, therefore, to test the hypothesis that, compared with placebo (PL), NO3−-rich beetroot juice (BR) supplementation would speed the phase II V̇o2kinetics (τp) and enhance exercise tolerance during severe-intensity exercise initiated from a baseline of moderate-intensity exercise. Nine healthy, physically active subjects were assigned in a randomized, double-blind, crossover design to receive BR (140 ml/day, containing ∼8 mmol of NO3−) and PL (140 ml/day, containing ∼0.003 mmol of NO3−) for 6 days. On days 4, 5, and 6 of the supplementation periods, subjects completed a double-step exercise protocol that included transitions from unloaded to moderate-intensity exercise (U→M) followed immediately by moderate to severe-intensity exercise (M→S). Compared with PL, BR elevated resting plasma nitrite concentration (PL: 65 ± 32 vs. BR: 348 ± 170 nM, P < 0.01) and reduced the V̇o2τpin M→S (PL: 46 ± 13 vs. BR: 36 ± 10 s, P < 0.05) but not U→M (PL: 25 ± 4 vs. BR: 27 ± 6 s, P > 0.05). During M→S exercise, the faster V̇o2kinetics coincided with faster near-infrared spectroscopy-derived muscle [deoxyhemoglobin] kinetics (τ; PL: 20 ± 9 vs. BR: 10 ± 3 s, P < 0.05) and a 22% greater time-to-task failure (PL: 521 ± 158 vs. BR: 635 ± 258 s, P < 0.05). Dietary supplementation with NO3−-rich BR juice speeds V̇o2kinetics and enhances exercise tolerance during severe-intensity exercise when initiated from an elevated metabolic rate.

scholarly journals High-intensity resistance exercise with low repetitions maintains endothelial function

2018 ◽  
Vol 315 (3) ◽  
pp. H681-H686 ◽  
Author(s):  
Takuma Morishima ◽  
Yosuke Tsuchiya ◽  
Motoyuki Iemitsu ◽  
Eisuke Ochi
Keyword(s):  
Blood Pressure ◽  
Endothelial Function ◽  
Resistance Exercise ◽  
Brachial Artery ◽  
High Intensity ◽  
Moderate Intensity ◽  
Pressure Measurements ◽  
Moderate Intensity Exercise ◽  
Vascular Effects ◽  
Exercise Induced

Resistance exercise impairs endothelial function, and this impairment is thought to be mediated by sustained elevation in blood pressure. Herein, we tested the hypothesis that resistance exercise-induced endothelial dysfunction would be prevented by high-intensity resistance exercise with low repetitions. This type of resistance exercise is known to induce temporal elevation in blood pressure due to low repetitions and a long resting period between sets. Thirteen young healthy subjects completed three randomized experimental trials as follows: 1) moderate-intensity exercise with moderate repetitions (moderate-moderate trial), 2) low-intensity exercise with high repetitions (low-high trial), and 3) high-intensity exercise with low repetitions (high-low trial). After baseline brachial artery flow-mediated dilation (FMD) and blood pressure measurements, subjects performed resistance exercise according to the different types of trials. Thereafter, brachial artery FMD and blood pressure measurements were repeated 10, 30, and 60 min after the exercise. Exercise-induced increases in blood flow and shear rate were significantly lower in the high-low trial than in the other two trials ( P < 0.05). Although systolic blood pressures were significantly elevated after exercise in all trials ( P < 0.05), the magnitudes of rise in blood pressure increase were significantly lower in the high-low trial than in the moderate-moderate and low-high trials ( P < 0.05). Moderate-moderate and low-high trials caused a significant impairment in brachial artery FMD ( P < 0.05), which could be prevented through high-intensity resistance exercise with low repetitions (  > 0.05). In conclusion, endothelial function was maintained by conducting high-intensity resistance exercise with low repetitions. NEW & NOTEWORTHY Data from the present study reveal that high-intensity resistance exercise with low repetitions can maintain endothelial function. Thus, this study provides the first evidence that the detrimental vascular effects of resistance exercise are preventable when resistance exercise is performed in high intensity with low repetitions. Listen to this article’s corresponding podcast at https://ajpheart.podbean.com/e/type-of-resistance-exercise-and-endothelial-function/ (Japanese version: https://ajpheart.podbean.com/e/japanese-language-podcast-type-of-resistance-exercise-and-endothelial-function/ ).

scholarly journals Effect of exercise intensity on postprandial lipemia, markers of oxidative stress, and endothelial function after a high-fat meal

2016 ◽  
Vol 41 (12) ◽  
pp. 1278-1284 ◽  
Author(s):  
Renata Lopes Krüger ◽  
Bruno Costa Teixeira ◽  
Juliano Boufleur Farinha ◽  
Rodrigo Cauduro Oliveira Macedo ◽  
Francesco Pinto Boeno ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Endothelial Function ◽  
Acute Exercise ◽  
Postprandial Lipemia ◽  
Moderate Intensity ◽  
Thiobarbituric Acid Reactive Substance ◽  
High Fat ◽  
Moderate Intensity Exercise ◽  
Postprandial Period ◽  
Fat Meal

The aim of this study was to compare the effects of 2 different exercise intensities on postprandial lipemia, oxidative stress markers, and endothelial function after a high-fat meal (HFM). Eleven young men completed 2-day trials in 3 conditions: rest, moderate-intensity exercise (MI-Exercise) and heavy-intensity exercise (HI-Exercise). Subjects performed an exercise bout or no exercise (Rest) on the evening of day 1. On the morning of day 2, an HFM was provided. Blood was sampled at fasting (0 h) and every hour from 1 to 5 h during the postprandial period for triacylglycerol (TAG), thiobarbituric acid reactive substance (TBARS), and nitrite/nitrate (NOx) concentrations. Flow-mediated dilatation (FMD) was also analyzed. TAG concentrations were reduced in exercise conditions compared with Rest during the postprandial period (P < 0.004). TAG incremental area under the curve (iAUC) was smaller after HI-Exercise compared with Rest (P = 0.012). TBARS concentrations were reduced in MI-Exercise compared with Rest (P < 0.041). FMD was higher in exercise conditions than Rest at 0 h (P < 0.02) and NOx concentrations were enhanced in MI-Exercise compared with Rest at 0 h (P < 0.01). These results suggest that acute exercise can reduce lipemia after an HFM. However, HI-Exercise showed to be more effective in reducing iAUC TAG, which might suggest higher protection against postprandial TAG enhancement. Conversely, MI-Exercise can be beneficial to attenuate the susceptibility of oxidative damage induced by an HFM and to increase endothelial function in the fasted state compared with Rest.

scholarly journals The Influence of an Acute Bout of Aerobic Exercise on Vascular Endothelial Function in Moderate Stages of Chronic Kidney Disease

Life ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 91
Author(s):  
Jeffrey S. Forsse ◽  
Zacharias Papadakis ◽  
Matthew N. Peterson ◽  
James Kyle Taylor ◽  
Burritt W. Hess ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Endothelial Function ◽  
Aerobic Exercise ◽  
Dependent Measure ◽  
Paraoxonase 1 ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Post Exercise

Chronic kidney disease (CKD) is directly influenced by the deleterious effects of systemic inflammation and oxidative stress. The vascular endothelium may transiently respond to aerobic exercise and improve post-exercise vascular renal function in moderate stages of CKD. Brachial artery flow-mediated dilation (FMD) is a nitric-oxide-dependent measure of endothelial function that is transiently potentiated by exercise. The purpose of the study was to determine the acute influence of a single bout of high-intensity interval exercise (HIIE) or steady-state moderate-intensity exercise (SSE) on endothelial dysfunction in moderate stages of CKD. Twenty participants (n = 6 men; n = 14 women) completed 30 min of SSE (65%) and HIIE (90:20%) of VO2reserve in a randomized crossover design. FMD measurements and blood samples were obtained before, 1 h, and 24 h post-exercise. FMD responses were augmented 1 h post-exercise in both conditions (p < 0.005). Relative to pre-exercise measures, total antioxidant capacity increased by 4.3% 24 h post-exercise (p = 0.012), while paraoxonase-1 was maintained 1 h and elevated by 6.1% 24 h after SSE, but not HIIE (p = 0.035). In summary, FMD can be augmented by a single episode of either HIIE or SSE in moderate stages of CKD. Modest improvements were observed in antioxidant analytes, and markers of oxidative stress were blunted in response to either SSE or HIIE.

Trans-resveratrol supplement lowers lipid peroxidation responses of exercise in male Wistar rats

2020 ◽  
pp. 1-6 ◽  
Author(s):  
Masoud Nasiri ◽  
Saja Ahmadizad ◽  
Mehdi Hedayati ◽  
Tayebe Zarekar ◽  
Mehdi Seydyousefi ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Antioxidant Capacity ◽  
Total Antioxidant Capacity ◽  
Wistar Rats ◽  
Enzymatic Antioxidants ◽  
Acute Response ◽  
Total Antioxidant ◽  
Male Wistar Rats ◽  
Exercise Induced ◽  
And Control

Abstract. Physical exercise increases free radicals production; antioxidant supplementation may improve the muscle fiber’s ability to scavenge ROS and protect muscles against exercise-induced oxidative damage. This study was designed to examine the effects of all-trans resveratrol supplementation as an antioxidant to mediate anti-oxidation and lipid per-oxidation responses to exercise in male Wistar rats. Sixty-four male Wistar rats were randomly divided into four equal number (n = 16) including training + supplement (TS), training (T), supplement (S) and control (C) group. The rats in TS and S groups received a dose of 10 mg/kg resveratrol per day via gavage. The training groups ran on a rodent treadmill 5 times per week at the speed of 10 m/min for 10 min; the speed gradually increased to 30 m/min for 60 minutes at the end of 12th week. The acute phase of exercise protocol included a speed of 25 m/min set to an inclination of 10° to the exhaustion point. Superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) activity, non-enzymatic antioxidants bilirubin, uric acid, lipid peroxidation levels (MDA) and the total antioxidant capacity (TAC) were measured after the exercise termination. The data were analyzed by using one-way ANOVA. The result showed that endurance training caused a significant increase in MDA level [4.5 ± 0.75 (C group) vs. 5.9 ± 0.41 nmol/l (T group)] whereas it decreased the total antioxidant capacity [8.5 ± 1.35 (C group) vs. 7.1 ± 0.55 mmol/l (T group)] (p = 0.001). In addition, GPx and CAT decreased but not significantly (p > 0.05). The training and t-resveratrol supplementation had no significant effect on the acute response of all variables except MDA [4.3 ± 1.4 (C group) vs. 4.0 ± 0.90 nmol/l (TS group)] (p = 0.001) and TAC [8.5 ± 0.90 (C group) vs. 6.6 ± 0.80 mmol/l (TS group)] (p = 0.004). It was concluded that resveratrol supplementation may prevent exercise-induced oxidative stress by preventing lipid peroxidation.

scholarly journals Total Antioxidant Capacity and Lipid Peroxidation Status in Cervical Cancer Patients Compared with Women Without Cervical Cancer in Bangladesh

2021 ◽  
Vol 19 (4) ◽  
Author(s):  
Taslima Nigar ◽  
Annekathryn Goodman ◽  
Shahana Pervin
Keyword(s):  
Oxidative Stress ◽  
Cervical Cancer ◽  
Lipid Peroxidation ◽  
Ascorbic Acid ◽  
Antioxidant Capacity ◽  
Cancer Patients ◽  
Total Antioxidant Capacity ◽  
Stress Index ◽  
Oxidative Stress Index ◽  
Total Antioxidant

Abstract Purpose Over the past several decades, research has suggested reactive oxygen species act as cofactors for cervical cancer development. The aim of this study is to evaluate the antioxidant and lipid peroxidation status in cervical cancer patients in Bangladesh. Methods From December 2017 to 2018, a cross-sectional observational study was conducted on 50 cervical cancer patients and 50 controls. Plasma levels of lipid peroxidation and total antioxidant capacity were measured. The Student’s t test was used for statistical analysis. P values less than 0.05 were taken as a level of significance. Results There was a significant reduction in total antioxidant levels in patients with cervical cancer, 972.77 ± 244.22 SD µmol equivalent to ascorbic acid/L, compared to normal controls, 1720.13 ± 150.81 SD µmol equivalent to ascorbic acid/L (P < 0.001). Levels of lipid peroxidation were found to be significantly higher in cervical cancer, 7.49 ± 2.13 SD µmol/L, than in women without cervical cancer, 3.28 ± 0.58 SD µmol/L (P < 0.001). The cervical cancer patients had significantly higher levels of oxidative stress index (0.83 ± 0.31) in comparison to controls (0.19 ± 0.04) (P < 0.001). Conclusion There was an increased oxidative stress index due to imbalance between lipid peroxidation generation and total antioxidant capacity in cervical cancer patients. Further studies are needed to explore the role of oxidative stress as a cofactor for cervical carcinogenesis.

scholarly journals Frontal and motor cortex oxygenation during maximal exercise in normoxia and hypoxia

2009 ◽  
Vol 106 (4) ◽  
pp. 1153-1158 ◽  
Author(s):  
Andrew W. Subudhi ◽  
Brittany R. Miramon ◽  
Matthew E. Granger ◽  
Robert C. Roach
Keyword(s):  
Motor Cortex ◽  
Near Infrared ◽  
Maximal Exercise ◽  
Acute Hypoxia ◽  
Moderate Intensity ◽  
Chamber Pressure ◽  
Motor Drive ◽  
Maximal Power ◽  
Moderate Intensity Exercise ◽  
Test Order

Reductions in prefrontal oxygenation near maximal exertion may limit exercise performance by impairing executive functions that influence the decision to stop exercising; however, whether deoxygenation also occurs in motor regions that more directly affect central motor drive is unknown. Multichannel near-infrared spectroscopy was used to compare changes in prefrontal, premotor, and motor cortices during exhaustive exercise. Twenty-three subjects performed two sequential, incremental cycle tests (25 W/min ramp) during acute hypoxia [79 Torr inspired Po2 (PiO2)] and normoxia (117 Torr PiO2) in an environmental chamber. Test order was balanced, and subjects were blinded to chamber pressure. In normoxia, bilateral prefrontal oxygenation was maintained during low- and moderate-intensity exercise but dropped 9.0 ± 10.7% (mean ± SD, P < 0.05) before exhaustion (maximal power = 305 ± 52 W). The pattern and magnitude of deoxygenation were similar in prefrontal, premotor, and motor regions ( R2 > 0.94). In hypoxia, prefrontal oxygenation was reduced 11.1 ± 14.3% at rest ( P < 0.01) and fell another 26.5 ± 19.5% ( P < 0.01) at exhaustion (maximal power = 256 ± 38 W, P < 0.01). Correlations between regions were high ( R2 > 0.61), but deoxygenation was greater in prefrontal than premotor and motor regions ( P < 0.05). Prefrontal, premotor, and motor cortex deoxygenation during high-intensity exercise may contribute to an integrative decision to stop exercise. The accelerated rate of cortical deoxygenation in hypoxia may hasten this effect.

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