Effect of voluntary hyperventilation with supplemental CO2on pulmonary O2uptake and leg blood flow kinetics during moderate-intensity exercise

Six male subjects [23 yr (SD 4)] performed repetitions (6–8) of two-legged, moderate-intensity, knee-extension exercise during two separate protocols that included step transitions from 3 W to 90% estimated lactate threshold (θL) performed as a single step (S3) and in two equal steps (S1, 3 W to ∼45% θL; S2, ∼45% θL to ∼90% θL). The time constants (τ) of pulmonary oxygen uptake (V̇o2), leg blood flow (LBF), heart rate (HR), and muscle deoxygenation (HHb) were greater ( P < 0.05) in S2 (τV̇o2, ∼52 s; τLBF, ∼ 39 s; τHR, ∼42 s; τHHb, ∼33 s) compared with S1 (τV̇o2, ∼24 s; τLBF, ∼21 s; τHR, ∼21 s; τHHb, ∼16 s), while the delay before an increase in HHb was reduced ( P < 0.05) in S2 (∼14 s) compared with S1 (∼20 s). The V̇o2 and HHb amplitudes were greater ( P < 0.05) in S2 compared with S1, whereas the LBF amplitude was similar in S2 and S1. Thus the slowed V̇o2 response in S2 compared with S1 is consistent with a mechanism whereby V̇o2 kinetics is limited, in part, by a slowed adaptation of blood flow and/or O2 transport when exercise was initiated from a baseline of moderate-intensity exercise.

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Hippocampal Blood Flow Is Increased After 20 min of Moderate-Intensity Exercise

Cerebral Cortex ◽

10.1093/cercor/bhz104 ◽

2019 ◽

Vol 30 (2) ◽

pp. 525-533 ◽

Cited By ~ 4

Author(s):

J J Steventon ◽

C Foster ◽

H Furby ◽

D Helme ◽

R G Wise ◽

...

Keyword(s):

Blood Flow ◽

Temporal Dynamics ◽

Therapeutic Potential ◽

Cerebrovascular Reactivity ◽

Moderate Intensity ◽

Moderate Intensity Exercise ◽

Exercise Interventions ◽

Before And After ◽

Exercise Induced

Abstract Long-term exercise interventions have been shown to be a potent trigger for both neurogenesis and vascular plasticity. However, little is known about the underlying temporal dynamics and specifically when exercise-induced vascular adaptations first occur, which is vital for therapeutic applications. In this study, we investigated whether a single session of moderate-intensity exercise was sufficient to induce changes in the cerebral vasculature. We employed arterial spin labeling magnetic resonance imaging to measure global and regional cerebral blood flow (CBF) before and after 20 min of cycling. The blood vessels’ ability to dilate, measured by cerebrovascular reactivity (CVR) to CO2 inhalation, was measured at baseline and 25-min postexercise. Our data showed that CBF was selectively increased by 10–12% in the hippocampus 15, 40, and 60 min after exercise cessation, whereas CVR to CO2 was unchanged in all regions. The absence of a corresponding change in hippocampal CVR suggests that the immediate and transient hippocampal adaptations observed after exercise are not driven by a mechanical vascular change and more likely represents an adaptive metabolic change, providing a framework for exploring the therapeutic potential of exercise-induced plasticity (neural, vascular, or both) in clinical and aged populations.

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Dynamics of middle cerebral artery blood flow velocity during moderate-intensity exercise

Journal of Applied Physiology ◽

10.1152/japplphysiol.00995.2016 ◽

2017 ◽

Vol 122 (5) ◽

pp. 1125-1133 ◽

Cited By ~ 13

Author(s):

Sandra A. Billinger ◽

Jesse C. Craig ◽

Sarah J. Kwapiszeski ◽

Jason-Flor V. Sisante ◽

Eric D. Vidoni ◽

...

Keyword(s):

Blood Flow ◽

Steady State ◽

Dynamic Response ◽

Moderate Intensity ◽

Artery Blood Flow ◽

Moderate Intensity Exercise ◽

Cerebrovascular Function ◽

Exercise Response ◽

Response Profile ◽

Health And Disease

The dynamic response to a stimulus such as exercise can reveal valuable insights into systems control in health and disease that are not evident from the steady-state perturbation. However, the dynamic response profile and kinetics of cerebrovascular function have not been determined to date. We tested the hypotheses that bilateral middle cerebral artery blood flow mean velocity (MCAV) increases exponentially following the onset of moderate-intensity exercise in 10 healthy young subjects. The MCAV response profiles were well fit to a delay (TD) + exponential (time constant, τ) model with substantial agreement for baseline [left (L): 69, right (R): 64 cm/s, coefficient of variation (CV) 11%], response amplitude (L: 16, R: 13 cm/s, CV 23%), TD (L: 54, R: 52 s, CV 9%), τ (L: 30, R: 30 s, CV 22%), and mean response time (MRT) (L: 83, R: 82 s, CV 8%) between left and right MCAV as supported by the high correlations (e.g., MRT r = 0.82, P < 0.05) and low CVs. Test-retest reliability was high with CVs for the baseline, amplitude, and MRT of 3, 14, and 12%, respectively. These responses contrasted markedly with those of three healthy older subjects in whom the MCAV baseline and exercise response amplitude were far lower and the kinetics slowed. A single older stroke patient showed baseline ipsilateral MCAV that was lower still and devoid of any exercise response whatsoever. We conclude that kinetics analysis of MCAV during exercise has significant potential to unveil novel aspects of cerebrovascular function in health and disease. NEW & NOTEWORTHY Resolution of the dynamic stimulus-response profile provides a greater understanding of the underlying the physiological control processes than steady-state measurements alone. We report a novel method of measuring cerebrovascular blood velocity (MCAv) kinetics under ecologically valid conditions from rest to moderate-intensity exercise. This technique reveals that brain blood flow increases exponentially following the onset of exercise with 1) a strong bilateral coherence in young healthy individuals, and 2) a potential for unique age- and disease-specific profiles.

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Age alters regional distribution of blood flow during moderate-intensity exercise

Journal of Applied Physiology ◽

10.1152/jappl.1995.79.4.1112 ◽

1995 ◽

Vol 79 (4) ◽

pp. 1112-1119 ◽

Cited By ~ 60

Author(s):

W. L. Kenney ◽

C. W. Ho

Keyword(s):

Heart Rate ◽

Blood Flow ◽

Renal Blood Flow ◽

Skin Blood Flow ◽

Forearm Blood Flow ◽

Regional Distribution ◽

Splanchnic Blood Flow ◽

Moderate Intensity ◽

Plasma Norepinephrine ◽

Moderate Intensity Exercise

During dynamic exercise in warm environments, requisite increases in skin and active muscle blood flows are supported by increasing cardiac output (Qc) and redistributing flow away from splanchnic and renal circulations. To examine the effect of age on these responses, six young (Y; 26 +/- 2 yr) and six older (O; 64 +/- 2 yr) men performed upright cycle exercise at 35 and 60% of peak O2 consumption (VO2peak) in 22 and 36 degrees C environments. To further isolate age, the two age groups were closely matched for VO2peak, weight, surface area, and body composition. Measurements included heart rate, Qc (CO2 rebreathing), skin blood flow (from increases in forearm blood flow (venous occlusion plethysmography), splanchnic blood flow (indocyanine green dilution), renal blood flow (p-amino-hippurate clearance), and plasma norepinephrine concentration. There were no significant age differences in Qc; however, in both environments the O group maintained Qc at a higher stroke volume and lower heart rate. At 60% VO2peak, forearm blood flow was significantly lower in the O subjects in each environment. Splanchnic blood flow fell (by 12–14% in both groups) at the lower intensity, then decreased to a greater extent at 60% VO2peak in Y than in O subjects (e.g., -45 +/- 2 vs. -33 +/- 3% for the hot environment, P < 0.01). Renal blood flow was lower at rest in the O group, remained relatively constant at 35% VO2peak, then decreased by 20–25% in both groups at 60% VO2peak. At 60% VO2peak, 27 and 37% more total blood flow was redistributed away from these two circulations in the Y than in the O group at 22 and 36 degrees, respectively. It was concluded that the greater increase in skin blood flow in Y subjects is partially supported by a greater redistribution of blood flow away from splanchnic and renal vascular beds.

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Moderate-intensity exercise with blood flow restriction on cardiopulmonary kinetics and efficiency during a subsequent high-intensity exercise in young women

Medicine ◽

10.1097/md.0000000000025368 ◽

2021 ◽

Vol 100 (31) ◽

pp. e25368

Author(s):

Robson F. Borges ◽

Gaspar R. Chiappa ◽

Paulo T. Muller ◽

Alexandra Correa Gervazoni Balbuena de Lima ◽

Lawrence Patrick Cahalin ◽

...

Keyword(s):

Blood Flow ◽

Young Women ◽

High Intensity ◽

High Intensity Exercise ◽

Blood Flow Restriction ◽

Moderate Intensity ◽

Moderate Intensity Exercise ◽

Flow Restriction

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The Adaptation Of Pulmonary O2 Uptake, Limb Blood Flow, And Muscle Deoxygenation During The Off-transient Of Moderate-intensity Exercise

Medicine & Science in Sports & Exercise ◽

10.1097/00005768-200505001-02317 ◽

2005 ◽

Vol 37 (Supplement) ◽

pp. S449

Author(s):

Gregory R. duManoir ◽

Darren S. DeLorey ◽

Aaron P. Heenan ◽

John M. Kowalchuk ◽

Donald H. Paterson

Keyword(s):

Blood Flow ◽

Moderate Intensity ◽

Limb Blood Flow ◽

O2 Uptake ◽

Moderate Intensity Exercise ◽

Muscle Deoxygenation

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Respiratory muscle blood flow during exercise: Effects of sex and ovarian cycle

Journal of Applied Physiology ◽

10.1152/japplphysiol.01007.2016 ◽

2017 ◽

Vol 122 (4) ◽

pp. 918-924 ◽

Cited By ~ 10

Author(s):

Joshua R. Smith ◽

K. Sue Hageman ◽

Craig A. Harms ◽

David C. Poole ◽

Timothy I. Musch

Keyword(s):

Blood Flow ◽

Respiratory Muscle ◽

Muscle Blood Flow ◽

Ovarian Cycle ◽

Transversus Abdominis ◽

Moderate Intensity ◽

Moderate Intensity Exercise ◽

Vascular Conductance ◽

Blood Flow Control ◽

Males And Females

Sex and ovarian cycle have been speculated to modify respiratory muscle blood flow control during exercise, but the findings are inconclusive. We tested the hypotheses that females would have higher respiratory muscle blood flow and vascular conductance (VC) compared with males during exercise and that this difference would be accentuated in proestrus vs. ovariectomized (OVA) females. Mean arterial pressure (carotid artery catheter) and respiratory muscle blood flow (radiolabeled microspheres) were measured during moderate-intensity (24 m/min, 10% grade) exercise in male ( n = 9), female ( n = 9), and OVA female ( n = 7) rats and near-maximal (60 m/min, 5% grade) exercise in male ( n = 5) and female ( n = 7) rats. At rest, diaphragm, intercostal, and transversus abdominis blood flow were not different ( P = 0.33) among groups. During moderate-intensity exercise, diaphragm (M: 124 ± 16; F: 140 ± 14; OVA: 140 ± 20 ml·min−1·100 g−1), intercostal (M: 33 ± 5; F: 34 ± 5; OVA: 30 ± 5 ml·min−1·100 g−1), and transversus abdominis blood flow (M: 24 ± 4; F: 35 ± 7; OVA: 35 ± 9 ml·min−1·100 g−1) significantly increased in all groups compared with rest but were not different ( P = 0.12) among groups. From rest to moderate-intensity exercise, diaphragm ( P < 0.03) and transversus abdominis ( P < 0.04) VC increased in all groups, whereas intercostal VC increased only for males and females ( P = 0.01). No differences ( P > 0.13) existed in VC among groups. During near-maximal exercise, diaphragm (M: 304 ± 62; F: 283 ± 17 ml·min−1·100 g−1), intercostal (M: 29 ± 8; F: 40 ± 6 ml·min−1·100 g−1), and transversus abdominis (M: 85 ± 14; F: 86 ± 9 ml·min−1·100 g−1) blood flow and VC were not different ( P > 0.27) between males and females. These data demonstrate that respiratory muscle blood flow and vascular conductance at rest and during exercise are not affected by sex or ovarian cycle in rats. NEW & NOTEWORTHY It has been proposed that sex and ovarian cycle modulate respiratory muscle blood flow control during exercise. We demonstrate herein that neither sex nor ovarian cycle influences respiratory muscle blood flow or vascular conductance at rest or during exercise in rats.

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Effect of high-fat and high-carbohydrate diets on pulmonary O2 uptake kinetics during the transition to moderate-intensity exercise

Journal of Applied Physiology ◽

10.1152/japplphysiol.00456.2014 ◽

2014 ◽

Vol 117 (11) ◽

pp. 1371-1379 ◽

Cited By ~ 9

Author(s):

J. A. Raper ◽

L. K. Love ◽

D. H. Paterson ◽

S. J. Peters ◽

G. J. F. Heigenhauser ◽

...

Keyword(s):

Blood Flow ◽

Time Constant ◽

Phase Ii ◽

Tricarboxylic Acid Cycle ◽

Microvascular Blood Flow ◽

Moderate Intensity ◽

High Fat ◽

Moderate Intensity Exercise ◽

Oxidation Rates ◽

High Carbohydrate

Mitochondrial pyruvate dehydrogenase (PDH) regulates the delivery of carbohydrate-derived substrate to the mitochondrial tricarboxylic acid cycle and electron transport chain. PDH activity at rest and its activation during exercise is attenuated following high-fat (HFAT) compared with high-carbohydrate (HCHO) diets. Given the reliance on carbohydrate-derived substrate early in transitions to exercise, this study examined the effects of HFAT and HCHO on phase II pulmonary O2 uptake (V̇o2p) kinetics during transitions into the moderate-intensity (MOD) exercise domain. Eight active adult men underwent dietary manipulations consisting of 6 days of HFAT (73% fat, 22% protein, 5% carbohydrate) followed immediately by 6 days of HCHO (10% fat, 10% protein, 80% carbohydrate); each dietary phase was preceded by a glycogen depletion protocol. Participants performed three MOD transitions from a 20 W cycling baseline to work rate equivalent to 80% of estimated lactate threshold on days 5 and 6 of each diet. Steady-state V̇o2p was greater ( P < 0.05), and respiratory exchange ratio and carbohydrate oxidation rates were lower ( P < 0.05) during HFAT. The phase II V̇o2p time constant (τV̇o2p) [HFAT 40 ± 16, HCHO 32 ± 19 s (mean ± SD)] and V̇o2p gain (HFAT 10.3 ± 0.8, HCHO 9.4 ± 0.7 ml·min−1·W−1) were greater ( P < 0.05) in HFAT. The overall adjustment (effective time constant) of muscle deoxygenation (Δ[HHb]) was not different between diets (HFAT 24 ± 4 s, HCHO 23 ± 4 s), which coupled with a slower τV̇o2p, indicates a slowed microvascular blood flow response. These results suggest that the slower V̇o2p kinetics associated with HFAT are consistent with inhibition and slower activation of PDH, a lower rate of pyruvate production, and/or attenuated microvascular blood flow and O2 delivery.

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