Peripheral and Central Chemoreceptor Control of Ventilation During Exercise in Humans

1994 ◽  
Vol 19 (3) ◽  
pp. 305-333 ◽  
Author(s):  
Susan A. Ward
Keyword(s):  
Steady State ◽  
High Intensity ◽  
High Intensity Exercise ◽  
Moderate Exercise ◽  
Arterial Blood Gas ◽  
Respiratory Compensation ◽  
Arterial Blood ◽  
The Stability ◽  
Exercise In Humans ◽  
Humoral Control

The stability of arterial blood gas tensions and pH during steady-state moderate exercise has suggested an important humoral element of ventilatory control in humans. However, the involvement of central and peripheral chemoreflexes in this humoral control remains controversial. This reflects, in large part, technical and interpretational limitations inherent in currently used estimators of chemoreflexes "sensitivity." Evidence suggests that the central chemoreceptors (a) contribute little during moderate exercise, given the relative stability of cerebrospinal pH, (b) constrain the hyperpnea of high-intensity exercise, consequent to the respiratory compensation for the metabolic acidemia, and (c) may play a role in the respiratory compensation during chronic metabolic acidemia. In contrast, the peripheral chemoreceptors appear to (a) exert considerable influence on ventilatory kinetics in moderate exercise, but are less important in the steady state, and (b) induce much of the respiratory compensation of high-intensity exercise. Key words: medullary chemoreceptors, carotid chemoreceptors, hyperoxia, ventilatory dynamics, metabolic acidemia

Dietary nitrate supplementation reduces the O2cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans

2009 ◽  
Vol 107 (4) ◽  
pp. 1144-1155 ◽  
Author(s):  
Stephen J. Bailey ◽  
Paul Winyard ◽  
Anni Vanhatalo ◽  
Jamie R. Blackwell ◽  
Fred J. DiMenna ◽  
...  
Keyword(s):  
High Intensity ◽  
Submaximal Exercise ◽  
High Intensity Exercise ◽  
Moderate Intensity ◽  
Nitrate Content ◽  
Time To Exhaustion ◽  
Moderate Exercise ◽  
Dietary Nitrate ◽  
Nitrate Supplementation ◽  
Exercise In Humans

Pharmacological sodium nitrate supplementation has been reported to reduce the O2cost of submaximal exercise in humans. In this study, we hypothesized that dietary supplementation with inorganic nitrate in the form of beetroot juice (BR) would reduce the O2cost of submaximal exercise and enhance the tolerance to high-intensity exercise. In a double-blind, placebo (PL)-controlled, crossover study, eight men (aged 19–38 yr) consumed 500 ml/day of either BR (containing 11.2 ± 0.6 mM of nitrate) or blackcurrant cordial (as a PL, with negligible nitrate content) for 6 consecutive days and completed a series of “step” moderate-intensity and severe-intensity exercise tests on the last 3 days. On days 4–6, plasma nitrite concentration was significantly greater following dietary nitrate supplementation compared with PL (BR: 273 ± 44 vs. PL: 140 ± 50 nM; P < 0.05), and systolic blood pressure was significantly reduced (BR: 124 ± 2 vs. PL: 132 ± 5 mmHg; P < 0.01). During moderate exercise, nitrate supplementation reduced muscle fractional O2extraction (as estimated using near-infrared spectroscopy). The gain of the increase in pulmonary O2uptake following the onset of moderate exercise was reduced by 19% in the BR condition (BR: 8.6 ± 0.7 vs. PL: 10.8 ± 1.6 ml·min−1·W−1; P < 0.05). During severe exercise, the O2uptake slow component was reduced (BR: 0.57 ± 0.20 vs. PL: 0.74 ± 0.24 l/min; P < 0.05), and the time-to-exhaustion was extended (BR: 675 ± 203 vs. PL: 583 ± 145 s; P < 0.05). The reduced O2cost of exercise following increased dietary nitrate intake has important implications for our understanding of the factors that regulate mitochondrial respiration and muscle contractile energetics in humans.

Effects of syringe material and temperature and duration of storage on the stability of equine arterial blood gas variables

2004 ◽  
Vol 31 (4) ◽  
pp. 250-257 ◽  
Author(s):  
Joanne C Deane ◽  
Mark P Dagleish ◽  
Agnes E M Benamou ◽  
Basil T Wolf ◽  
David Marlin
Keyword(s):  
Blood Gas ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Duration Of Storage ◽  
The Stability

Carbohydrates do not accelerate force recovery after glycogen‐depleting followed by high‐intensity exercise in humans

2020 ◽  
Vol 30 (6) ◽  
pp. 998-1007
Author(s):  
Arthur J. Cheng ◽  
Thomas Chaillou ◽  
Sigitas Kamandulis ◽  
Andrejus Subocius ◽  
Håkan Westerblad ◽  
...  
Keyword(s):  
High Intensity ◽  
High Intensity Exercise ◽  
Force Recovery ◽  
Exercise In Humans ◽  
Accelerate Force

Pulmonary O2 uptake kinetics as a determinant of high-intensity exercise tolerance in humans

2011 ◽  
Vol 110 (6) ◽  
pp. 1598-1606 ◽  
Author(s):  
Scott R. Murgatroyd ◽  
Carrie Ferguson ◽  
Susan A. Ward ◽  
Brian J. Whipp ◽  
Harry B. Rossiter
Keyword(s):  
Steady State ◽  
High Intensity ◽  
Exercise Tolerance ◽  
Slow Component ◽  
Progressive Increase ◽  
High Intensity Exercise ◽  
Exercise Intolerance ◽  
Exercise Onset ◽  
O2 Uptake Kinetics ◽  
Two Parameters

Tolerance to high-intensity constant-power (P) exercise is well described by a hyperbola with two parameters: a curvature constant (W′) and power asymptote termed “critical power” (CP). Since the ability to sustain exercise is closely related to the ability to meet the ATP demand in a steady state, we reasoned that pulmonary O2 uptake (V̇o2) kinetics would relate to the P-tolerable duration (tlim) parameters. We hypothesized that 1) the fundamental time constant (τV̇o2) would relate inversely to CP; and 2) the slow-component magnitude (ΔV̇o2sc) would relate directly to W′. Fourteen healthy men performed cycle ergometry protocols to the limit of tolerance: 1) an incremental ramp test; 2) a series of constant-P tests to determine V̇o2max, CP, and W′; and 3) repeated constant-P tests (WR6) normalized to a 6 min tlim for τV̇o2 and ΔV̇o2sc estimation. The WR6 tlim averaged 365 ± 16 s, and V̇o2max (4.18 ± 0.49 l/min) was achieved in every case. CP (range: 171–294 W) was inversely correlated with τV̇o2 (18–38 s; R2 = 0.90), and W′ (12.8–29.9 kJ) was directly correlated with ΔV̇o2sc (0.42–0.96 l/min; R2 = 0.76). These findings support the notions that 1) rapid V̇o2 adaptation at exercise onset allows a steady state to be achieved at higher work rates compared with when V̇o2 kinetics are slower; and 2) exercise exceeding this limit initiates a “fatigue cascade” linking W′ to a progressive increase in the O2 cost of power production (V̇o2sc), which, if continued, results in attainment of V̇o2max and exercise intolerance. Collectively, these data implicate V̇o2 kinetics as a key determinant of high-intensity exercise tolerance in humans.

scholarly journals Dynamic asymmetry of phosphocreatine concentration and O 2 uptake between the on‐ and off‐transients of moderate‐ and high‐intensity exercise in humans

2002 ◽  
Vol 541 (3) ◽  
pp. 991-1002 ◽  
Author(s):  
H. B. Rossiter ◽  
S. A. Ward ◽  
J. M. Kowalchuk ◽  
F. A. Howe ◽  
J. R. Griffiths ◽  
...  
Keyword(s):  
High Intensity ◽  
High Intensity Exercise ◽  
Exercise In Humans

scholarly journals Haemodynamic and metabolic responses of the lower limb after high intensity exercise in humans

1996 ◽  
Vol 81 (2) ◽  
pp. 173-187 ◽  
Author(s):  
ST Hussain ◽  
RE Smith ◽  
S Medbak ◽  
RF Wood ◽  
BJ Whipp
Keyword(s):  
Lower Limb ◽  
High Intensity ◽  
High Intensity Exercise ◽  
Metabolic Responses ◽  
Exercise In Humans

Adrenergic regulation of HSL serine phosphorylation and activity in human skeletal muscle during the onset of exercise

2006 ◽  
Vol 291 (4) ◽  
pp. R1094-R1099 ◽  
Author(s):  
Jason L. Talanian ◽  
Rebecca J. Tunstall ◽  
Matthew J. Watt ◽  
Mylinh Duong ◽  
Christopher G. R. Perry ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cyclic Amp ◽  
High Intensity ◽  
Human Skeletal Muscle ◽  
High Intensity Exercise ◽  
Serine Phosphorylation ◽  
Hormone Sensitive Lipase ◽  
Peak Oxygen Consumption ◽  
Adrenergic Stimulation ◽  
Arterial Blood

Skeletal muscle hormone-sensitive lipase (HSL) activity is increased by contractions and increases in blood epinephrine (EPI) concentrations and cyclic AMP activation of the adrenergic pathway during prolonged exercise. To determine the importance of hormonal stimulation of HSL activity during the onset of moderate- and high-intensity exercise, nine men [age 24.3 ± 1.2 yr, 80.8 ± 5.0 kg, peak oxygen consumption (V̇o2 peak) 43.9 ± 3.6 ml·kg−1·min−1] cycled for 1 min at ∼65% V̇o2 peak, rested for 60 min, and cycled at ∼90% V̇o2 peak for 1 min. Skeletal muscle biopsies were taken pre- and postexercise, and arterial blood was sampled throughout exercise. Arterial EPI increased ( P < 0.05) postexercise at 65% (0.45 ± 0.10 to 0.78 ± 0.27 nM) and 90% V̇o2 peak (0.57 ± 0.34 to 1.09 ± 0.50 nM). HSL activity increased ( P < 0.05) following 1 min of exercise at 65% V̇o2 peak [1.05 ± 0.39 to 1.78 ± 0.54 mmol·min−1·kg dry muscle (dm)−1] and 90% V̇o2 peak (1.07 ± 0.24 to 1.91 ± 0.62 mmol·min−1·kg dm−1). Cyclic AMP content also increased ( P < 0.05) at both exercise intensities (65%: 1.52 ± 0.67 to 2.75 ± 1.12, 90%: 1.85 ± 0.65 to 2.64 ± 0.93 μmol/kg dm). HSL Ser660 phosphorylation (∼55% increase) and ERK1/2 phosphorylation (∼33% increase) were augmented following exercise at both intensities, whereas HSL Ser563 and Ser565 phosphorylation were not different from rest. The results indicate that increases in arterial EPI concentration during the onset of moderate- and high-intensity exercise increase cyclic AMP content, which results in the phosphorylation of HSL Ser660. This adrenergic stimulation contributes to the increase in HSL activity that occurs in human skeletal muscle in the first minute of exercise at 65% and 90% V̇o2 peak.

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