Cardiac Autonomic and Physiological Responses to Moderate- intensity Exercise in Hypoxia

2019 ◽  
Vol 40 (14) ◽  
pp. 886-896 ◽  
Author(s):  
Alessandro Fornasiero ◽  
Spyros Skafidas ◽  
Federico Stella ◽  
Andrea Zignoli ◽  
Aldo Savoldelli ◽  
...  
Keyword(s):  
Ventilatory Threshold ◽  
Mechanical Load ◽  
Acute Hypoxia ◽  
Physiological Responses ◽  
Metabolic Stress ◽  
Absolute Intensity ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Parasympathetic Reactivation ◽  
Hypoxic Exercise

AbstractExercise physiological responses can be markedly affected by acute hypoxia. We investigated cardiac autonomic and physiological responses to different hypoxic training protocols. Thirteen men performed three exercise sessions (5×5-min; 1-min passive recovery): normoxic exercise at 80% of the power output (PO) at the first ventilatory threshold (N), hypoxic exercise (FiO2=14.2%) with the same PO as N (HPO) and hypoxic exercise at the same heart rate (HR) as N (HHR). PO was lower in HHR (21.1±9.3%) compared to N and HPO. Mean HR was higher in HPO (154±11 bpm, p<0.01) than N and HHR (139±10 vs. 138±9 bpm; p=0.80). SpO2 was reduced (p<0.01) to a similar extent (p>0.05) in HPO and HHR compared to N. HR recovery (HRR) and HR variability indices were similar in N and HHR (p>0.05) but reduced in HPO (p<0.05), mirroring a delayed parasympathetic reactivation. Blood lactate and ventilation were similar in N and HHR (p>0.05) and increased in HPO (p<0.001). During recovery oxygen consumption and ventilation were similar in N and HHR (p>0.05) and increased in HPO (p<0.01). Moderate HR-matched hypoxic exercise triggers similar cardiac autonomic and physiological responses to normoxic exercise with a reduced mechanical load. On the contrary, the same absolute intensity exercise in hypoxia is associated with increased exercise-induced metabolic stress and delayed cardiac autonomic recovery.

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.

Fat and carbohydrate metabolism during exercise in elderly and young subjects

1996 ◽  
Vol 271 (6) ◽  
pp. E983-E989 ◽  
Author(s):  
S. Sial ◽  
A. R. Coggan ◽  
R. Carroll ◽  
J. Goodwin ◽  
S. Klein
Keyword(s):  
Young Adults ◽  
Carbohydrate Metabolism ◽  
Relative Intensity ◽  
The Elderly ◽  
Absolute Intensity ◽  
Substrate Oxidation ◽  
Carbohydrate Oxidation ◽  
Moderate Intensity ◽  
Elderly Subjects ◽  
Moderate Intensity Exercise

We evaluated the effect of aging on fat and carbohydrate metabolism during moderate intensity exercise. Glycerol, free fatty acid (FFA), and glucose rate of appearance (Ra) in plasma and substrate oxidation were determined during 60 min of cycle ergometer exercise in six elderly (73 +/- 2 yr) and six young adults (26 +/- 2 yr) matched by gender and lean body mass. The elderly group was studied during exercise performed at 56 +/- 3% of maximum oxygen uptake, whereas the young adults were studied during exercise performed at the same absolute and at a similar relative intensity as the elderly subjects. Mean fat oxidation during exercise was 25-35% lower in the elderly subjects than in the young adults exercising at either the same absolute or similar relative intensities (P < 0.05). Mean carbohydrate oxidation in the elderly group was 35% higher than the young adults exercising at the same absolute intensity (P < 0.001) but 40% lower than the young adults exercising at the same relative intensity (P < 0.001). Average FFA Ra in the elderly subjects was 85% higher than in the young adults exercising at the same absolute intensity (P < 0.05) but 35% lower than the young adults exercising at a similar relative intensity (P < 0.05). We conclude that fat oxidation is decreased while carbohydrate oxidation is increased during moderate intensity exercise in elderly men and women. The shift in substrate oxidation was caused by age-related changes in skeletal muscle respiratory capacity because lipolytic rates and FFA availability were not rate limiting in the older subjects.

scholarly journals Physiological Responses During Multiplay Exergaming in Young Adult Males are Game-Dependent

2015 ◽  
Vol 46 (1) ◽  
pp. 263-271 ◽  
Author(s):  
Stephen McGuire ◽  
Mark ET Willems
Keyword(s):  
Body Mass ◽  
Minute Ventilation ◽  
Physiological Responses ◽  
Body Height ◽  
Health Benefits ◽  
Moderate Intensity ◽  
Field Energy ◽  
Moderate Intensity Exercise ◽  
Similar Time ◽  
Gas Exchange System

AbstractRegular moderate-intensity exercise provides health benefits. The aim of this study was to examine whether the selected exercise intensity and physiological responses during exergaming in a single and multiplayer mode in the same physical space were game-dependent. Ten males (mean ±SD, age: 23 ±5 years, body mass: 84.2 ±15.6 kg, body height: 180 ±7 cm, body mass index: 26.0 ±4.0 kg·m−2) played the games Kinect football, boxing and track & field (3 × ~10 min, ~ 2 min rest periods) in similar time sequence in two sessions. Physiological responses were measured with the portable Cosmed K4b2 pulmonary gas exchange system. Single play demands were used to match with a competitive opponent in a multiplay mode. A within-subjects crossover design was used with one-way ANOVA and a post-hoc t-test for analysis (p<0.05). Minute ventilation, oxygen uptake and the heart rate were at least 18% higher during a multiplayer mode for Kinect football and boxing but not for track & field. Energy expenditure was 21% higher during multiplay football. Single play track & field had higher metabolic equivalent than single play football (5.7 ±1.6, range: 3.2-8.6 vs 4.1 ±1.0, range: 3.0-6.1, p<0.05). Exergaming in a multiplayer mode can provide higher physiological demands but the effects are game-dependent. It seems that exergaming with low intensity in a multiplayer mode may provide a greater physical challenge for participants than in a single play mode but may not consistently provide sufficient intensity to acquire health benefits when played regularly as part of a programme to promote and maintain health in young adults.

Affect and Self-Efficacy Responses During Moderate-Intensity Exercise Among Low-Active Women: The Effect of Cognitive Appraisal

2010 ◽  
Vol 32 (2) ◽  
pp. 154-175 ◽  
Author(s):  
Amy S. Welch ◽  
Angie Hulley ◽  
Mark Beauchamp
Keyword(s):  
Self Efficacy ◽  
Acute Exercise ◽  
Cognitive Appraisal ◽  
Ventilatory Threshold ◽  
Rebound Effect ◽  
Exercise Program ◽  
Exercise Duration ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Ergometer Exercise

To investigate the relationship between cognitive and affective responses during acute exercise, 24 low-active females completed two 30-min bouts of cycle ergometer exercise at 90% of the ventilatory threshold. In one condition participants had full knowledge of the exercise duration (KD); in the other, exercise duration was unknown (UD). Affect and self-efficacy were measured before and every 3 min during exercise, and affect was also measured postexercise. Affect declined throughout the first half of both conditions, and continued its decline until the end of the UD condition, when a rebound effect was observed. Self-efficacy during exercise displayed a similar pattern. Hierarchical regression analyses demonstrated that during-exercise self-efficacy was a stronger predictor of during-exercise affect than preexercise self-efficacy, and that this relationship was strongest at the end of exercise when duration was unknown. These results indicate that repetitive cognitive appraisal of self and the task could impact the exercise experiences of low-active women during the adoption phase of an exercise program.

Exercise intensity dependent relevance of protective textile properties for human thermo-physiology

2016 ◽  
Vol 87 (12) ◽  
pp. 1425-1434 ◽  
Author(s):  
Piero Fontana ◽  
Fabio Saiani ◽  
Marc Grütter ◽  
Jean-Philippe Croset ◽  
André Capt ◽  
...  
Keyword(s):  
Functional Properties ◽  
Exercise Intensity ◽  
Human Subject ◽  
Core Body Temperature ◽  
Physiological Responses ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Exercise Tests ◽  
Physiological Relevance ◽  
Low Intensity Exercise

During firefighting, thermoregulation is challenged due to a combination of harsh environmental conditions, high metabolic rates and personal protective clothing (PPC). Consequently, investigations of thermoregulation in firefighters should not only consider climate and exercise intensity, but technical properties of textiles too. Therefore, laboratory textile performance simulations may provide additional insights into textile-dependent thermoregulatory responses to exercise. In order to investigate the thermo-physiological relevance of textile properties and to test how different garments affect thermoregulation at different exercise intensities, we analyzed the results of a standard laboratory test and human subject trials by relating functional properties of textiles to thermo-physiological responses. Ten professional, healthy, male firefighters (age: 43 ± 6 y, weight: 84.3 ± 10.3kg, height: 1.79 ± 0.05m) performed low and moderate intensity exercise wearing garments previously evaluated with a sweating torso system to characterize thermal and evaporative properties. Functional properties of PPC and the control garment differed markedly. Consequently, skin temperature was higher using PPC at both exercise intensities (low: 36.27 ± 0.32 versus 36.75 ± 0.15℃, P < 0.05; moderate: 36.53 ± 0.34 versus 37.18 ± 0.23℃, P < 0.001), while core body temperature was only higher for PPC at moderate (37.54 ± 0.24 versus 37.83 ± 0.27℃, P < 0.05), but not low-intensity exercise (37.26 ± 0.21 versus 37.21 ± 0.19, P = 0.685). Differences in thermal and evaporative properties between textiles are reflected in thermo-physiological responses during human subject trials. However, an appropriate exercise intensity has to be chosen in order to challenge textile performance during exercise tests.

scholarly journals Impact of type 2 diabetes on cardiorespiratory function and exercise performance

2016 ◽  
Author(s):  
Joanie Caron ◽  
Gregory R. duManoir ◽  
Lawrence Labrecque ◽  
Audrey Chouinard ◽  
Annie Ferland ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Exercise Performance ◽  
Ventilatory Threshold ◽  
Exponential Model ◽  
Cycle Ergometer ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Cardiorespiratory Function ◽  
The Impact

AbstractThe aim of this study was to examine the impact of well-controlled uncomplicated type 2 diabetes (T2D) on exercise performance. Six obese sedentary men with T2D and 7 control participants without diabetes matched for age, sex and body mass index were recruited. Anthropometric characteristics, blood samples, resting cardiac and pulmonary functions and maximal oxygen uptake (VO2max) and ventilatory threshold were measured on a first visit. On the four subsequent visits, participants performed step transitions (6 min) of moderate-intensity exercise on an upright cycle ergometer from unloaded pedaling to 80 % of ventilatory threshold. VO2(τVO2) and HR (τHR) kinetics were characterized with a mono-exponential model. VO2max (27.8±4.0 vs. 27.5±5.3 ml kg-1min-1; p=0.95), τVO2(43±6 vs. 43±10 s; p=0.73) and τHR (42±17 vs. 43±13 s; p=0.94) were similar between diabetics and controls respectively. The remaining variables were also similar between groups. These results suggest that well-controlled T2D is not associated with a reduction in VO2max or slower τVO2and τHR.

Oxygen uptake kinetics in endurance-trained and untrained postmenopausal women

2013 ◽  
Vol 38 (2) ◽  
pp. 154-160 ◽  
Author(s):  
Shilpa Dogra ◽  
Matthew D. Spencer ◽  
Juan M. Murias ◽  
Donald H. Paterson
Keyword(s):  
Heart Rate ◽  
Oxygen Uptake ◽  
Older Women ◽  
Near Infrared ◽  
Ventilatory Threshold ◽  
Vastus Lateralis ◽  
Hemoglobin Concentration ◽  
Oxygen Uptake Kinetics ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise

The rate of adjustment for pulmonary oxygen uptake (τV̇O2p) is slower in untrained and in older adults. Near-infrared spectroscopy (NIRS) has shed light on potential mechanisms underlying this in young men and women and in older men; however, there is no such data available in older women. The purpose of this study was to gain a better understanding of the mechanisms of slower τV̇O2p in older women who were either endurance-trained or untrained. Endurance-trained (n = 10; age, 62.6 ± 1.0 years) and untrained (n = 9; age, 69.1 ± 2.2 years) older women attended 2 maximal and 2 submaximal (90% of ventilatory threshold) exercise sessions. Oxygen uptake (V̇O2) was measured breath by breath, using a mass spectrometer, and changes in deoxygenated hemoglobin concentration of the vastus lateralis ([HHb]) were measured using NIRS. Heart rate was measured continuously with a 3-lead electrocardiogram. τV̇O2p was faster in trained (35.1 ± 5.5 s) than in untrained (57.0 ± 8.1 s) women. The normalized [HHb] to V̇O2 ratio, an indicator of muscle O2 delivery to O2 utilization, indicated a smaller overshoot in trained (1.09 ± 0.1) than in untrained (1.39 ± 0.1) women. Heart rate data indicated a faster adjustment of heart rate in trained (33.0 ± 13.0) than in untrained (68.7 ± 14.1) women. The pairing of V̇O2p data with NIRS-derived [HHb] data indicates that endurance-trained older women likely have better matching of O2 delivery to O2 utilization than older untrained women during moderate-intensity exercise, leading to a more rapid adjustment of V̇O2p.

scholarly journals Effect of New Zealand Blackcurrant Extract on Physiological Responses at Rest and during Brisk Walking in Southeast Asian Men: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study

Nutrients ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1732 ◽  
Author(s):  
Mark Willems ◽  
Nisakorn Parktin ◽  
Waree Widjaja ◽  
Amornpan Ajjimaporn
Keyword(s):  
New Zealand ◽  
Physiological Responses ◽  
Treadmill Walking ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Double Blind ◽  
Metabolic Equivalent ◽  
New Zealand Blackcurrant ◽  
Asian Men ◽  
Caucasian Men

New Zealand blackcurrant (NZBC) extract affects cardiovascular and metabolic responses during rest and exercise in Caucasian men. Ethnicity and nutritional habits may affect responses to nutritional ergogenic aids. We examined the effects of NZBC extract on cardiovascular, metabolic, and physiological responses during seated rest and moderate-intensity exercise in Southeast Asian men. Seventeen healthy Thai men (age: 22 ± 3 years; body mass index (BMI): 21.8 ± 1.1 kg·m−2) participated. Resting metabolic equivalent (1-MET) was measured (Oxycon™ mobile, Germany), and an incremental walking protocol was completed to establish the relationship between walking speed and MET. In a double-blind, randomized, placebo-controlled, crossover design, cardiovascular (Physioflow, n = 12) and physiological responses (Oxycon, n = 17) were measured during both seated rest and a 30-min treadmill walk at five metabolic equivalent (5-MET), with either a seven-day intake of placebo (PL) or two capsules of NZBC extract (each 300 mg capsule contains 35% blackcurrant extract) with a 14-day washout. Paired t-tests were used with significance accepted at p < 0.05 and a trend for 0.05 > p ≤ 0.10. During 30 min of treadmill walking at 5-MET, no differences were observed for heart rate and substrate oxidation. With intake of NZBC during treadmill walking, there was a trend for increased stroke volume by 12% (PL: 83.2 ± 25.1; NZBC: 93.0 ± 24.3 mL; p = 0.072) and cardiac output increased by 12% (PL: 9.2 ± 2.6; NZBC: 10.3 ± 2.8 L·min−1; p = 0.057). Systemic vascular resistance decreased by 10% (PL: 779 ± 267; NZBC: 697 ± 245 dyn·s·cm−5; p = 0.048). NZBC extract had no effect on metabolic, physiological, and cardiovascular parameters during seated rest and exercise-induced fat oxidation in Thai men, in contrast to observations in Caucasian men. During treadmill walking, Thai men showed cardiovascular response, indicating vasodilatory effects during moderate-intensity exercise with the intake of NZBC extract. Our findings suggest that the ergogenic responses to anthocyanin intake from New Zealand blackcurrant may be ethnicity-dependent.

Peripheral chemoreceptor function after carbonic anhydrase inhibition during moderate-intensity exercise

1999 ◽  
Vol 86 (5) ◽  
pp. 1544-1551 ◽  
Author(s):  
Barry W. Scheuermann ◽  
John M. Kowalchuk ◽  
Donald H. Paterson ◽  
David A. Cunningham
Keyword(s):  
Steady State ◽  
Carbonic Anhydrase ◽  
Ventilatory Threshold ◽  
Ventilatory Response ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Peripheral Chemoreceptor ◽  
Ventilatory Drive ◽  
Carbonic Anhydrase Inhibition ◽  
End Tidal

The effect of carbonic anhydrase inhibition with acetazolamide (Acz, 10 mg/kg) on the ventilatory response to an abrupt switch into hyperoxia (end-tidal [Formula: see text]= 450 Torr) and hypoxia (end-tidal[Formula: see text] = 50 Torr) was examined in five male subjects [30 ± 3 (SE) yr]. Subjects exercised at a work rate chosen to elicit an O2 uptake equivalent to 80% of the ventilatory threshold. Ventilation (V˙e) was measured breath by breath. Arterial oxyhemoglobin saturation (%[Formula: see text]) was determined by ear oximetry. After the switch into hyperoxia, V˙eremained unchanged from the steady-state exercise prehyperoxic value (60.6 ± 6.5 l/min) during Acz. During control studies (Con),V˙e decreased from the prehyperoxic value (52.4 ± 5.5 l/min) by ∼20% (V˙enadir = 42.4 ± 6.3 l/min) within 20 s after the switch into hyperoxia. V˙e increased during Acz and Con after the switch into hypoxia; the hypoxic ventilatory response was significantly lower after Acz compared with Con [Acz, change (Δ) inV˙e/[Formula: see text]= 1.54 ± 0.10 l ⋅ min−1 ⋅ [Formula: see text] −1; Con, ΔV˙e/[Formula: see text]= 2.22 ± 0.28 l ⋅ min−1 ⋅ [Formula: see text] −1]. The peripheral chemoreceptor contribution to the ventilatory drive after acute Acz-induced carbonic anhydrase inhibition is not apparent in the steady state of moderate-intensity exercise. However, Acz administration did not completely attenuate the peripheral chemoreceptor response to hypoxia.

Metabolism- and sex-dependent critical WBGT limits at rest and during exercise in the heat

2021 ◽  
Author(s):  
S. Tony Wolf ◽  
Mireille A. Folkerts ◽  
Rachel M. Cottle ◽  
Hein A.M. Daanen ◽  
W. Larry Kenney
Keyword(s):  
Sex Differences ◽  
Thermal Environment ◽  
Water Vapor Pressure ◽  
Absolute Intensity ◽  
Body Core Temperature ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Wet Bulb Globe Temperature ◽  
Globe Temperature ◽  
Environmental Limits

Critical environmental limits are environmental thresholds above which heat gain exceeds heat loss and body core temperature (Tc) cannot be maintained at equilibrium. Those limits can be represented as critical wet-bulb globe temperature (WBGTcrit), a validated index that represents the overall thermal environment. Little is known about WBGTcrit at rest and during low-to-moderate intensity exercise, or sex differences in WBGTcrit, in unacclimated young adults. The following hypotheses were tested: (1) WBGTcrit progressively decreases as metabolic heat production (Mnet) increases, (2) no sex differences in WBGTcrit occur at rest, and (3) WBGTcrit is lower during absolute-intensity exercise but higher at relative intensities in women compared to men. Thirty-six participants (19M/17W; 23±4 yr) were tested at rest, during light, absolute-intensity exercise (10 W), or during moderate, relative-intensity exercise (30% V̇O2max) in an environmental chamber. Dry-bulb temperature was clamped as relative humidity or ambient water vapor pressure was increased until an upward inflection was observed in Tc (rectal or esophageal temperature). Sex-aggregated WBGTcrit was lower during 10 W (32.9±1.7°C, P<0.0001) and 30% V̇O2max (31.6±1.1°C, P<0.0001) exercise vs. rest (35.3±0.8°C), and lower at 30% V̇O2max vs. 10 W (P=0.01). WBGTcrit was similar between sexes at rest (35.6±0.8°C vs. 35.0±0.8°C, P=0.83), but lower during 10 W (31.9±1.7°C vs. 34.1±0.3°C, P<0 .01) and higher during 30% V̇O2max (32.4±0.8°C vs. 30.8±0.9°C, P=0.03) exercise in women vs. men. These findings suggest that WBGTcrit decreases as Mnet increases, no sex differences occur in WBGTcrit at rest, and sex differences in WBGTcrit during exercise depend upon absolute vs. relative intensities.

Sign in / Sign up

Export Citation Format

Share Document