Interaction of Factors Determining Critical Power

Sports Medicine, Journal Year: 2023, Volume and Issue: 53(3), P. 595 - 613

Published: Jan. 9, 2023

Abstract The physiological determinants of high-intensity exercise tolerance are important for both elite human performance and morbidity, mortality disease in clinical settings. asymptote the hyperbolic relation between external power time to task failure, critical power, represents threshold intensity above which systemic intramuscular metabolic homeostasis can no longer be maintained. After ~ 60 years research into phenomenon a clear understanding its has emerged. purpose present review is critically examine this contemporary evidence order explain underpinnings power. Evidence demonstrating that alterations convective diffusive oxygen delivery impact upon first addressed. Subsequently, considered shows rates muscle utilisation, inferred via kinetics pulmonary consumption, influence data reveal picture flux along every step transport utilisation pathways It also influenced by motor unit recruitment patterns. On basis, it proposed act concert with determine intracellular milieu state fatigue within myocytes. This interacts exercising mass patterns ultimately

Language: Английский

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How Priming Exercise Affects Oxygen Uptake Kinetics: From Underpinning Mechanisms to Endurance Performance

Sports Medicine, Journal Year: 2023, Volume and Issue: 53(5), P. 959 - 976

Published: April 3, 2023

The observation that prior heavy or severe-intensity exercise speeds overall oxygen uptake ([Formula: see text]O2) kinetics, termed the "priming effect", has garnered significant research attention and its underpinning mechanisms have been hotly debated. In first part of this review, evidence for against (1) lactic acidosis, (2) increased muscle temperature, (3) O2 delivery, (4) altered motor unit recruitment patterns (5) enhanced intracellular utilisation in priming effect is discussed. Lactic acidosis temperature are most likely not key determinants effect. Whilst increases many studies demonstrated an delivery a prerequisite Motor by exercise, these alterations consistent with some observed changes [Formula: text]O2 kinetics humans. Enhancements play central role mediating effect, probably related to elevated mitochondrial calcium levels parallel activation enzymes at onset second bout. latter portion implications on parameters power-duration relationship subsequent endurance performance depends critically upon which phases response altered. A reduced slow component fundamental phase amplitude tend increase work performable above critical power (i.e. W´), whereas reduction time constant following results power.

Language: Английский

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A review on time domain diffuse optics: principles and applications on human biological tissues

Deleted Journal, Journal Year: 2025, Volume and Issue: unknown

Published: April 9, 2025

Abstract The term diffusive media refers to all the for which photon diffusion equation provides an accurate description of light propagation. Indeed, this is case a plethora natural media, such as biological tissues and agricultural products, when illuminated by red near-infrared light. Diffuse Optics (DO) branch that studies how absorption scattering phenomena affect propagation in media. In review paper, we present introduction time domain (TD) DO, specific implementation DO employs picosecond pulses, fast sensitive photodetectors timing electronics record distribution time-of-flight (or path lengths) By interpreting TD signals with physical model provided theory, it possible estimate properties medium can be related physiological pathological conditions. We focus on principles building blocks instrumentation, applications targeting human (such brain, breast, muscle, others).

Language: Английский

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High-intensity exercise impairs extradiaphragmatic respiratory muscle perfusion in patients with COPD

Journal of Applied Physiology, Journal Year: 2020, Volume and Issue: 130(2), P. 325 - 341

Published: Oct. 29, 2020

The study investigated whether high-intensity exercise impairs inspiratory and expiratory muscle perfusion in patients with chronic obstructive pulmonary disease (COPD). We compared respiratory local between constant-load cycling[sustained at 80% peak work rate (WRpeak)] voluntary normocapnic hyperpnea reproducing similar of breathing (WoB) 18 [forced volume the first second (FEV1): 58 ± 24% predicted]. Local blood flow index (BFI), using indocyanine green dye, fractional oxygen saturation (%StiO2) were simultaneously assessed by near-infrared spectroscopy (NIRS) over intercostal, scalene, rectus abdominis, vastus lateralis muscles. Cardiac output (impedance cardiography), WoB (esophageal/gastric balloon catheter), diaphragmatic extradiaphragmatic electromyographic activity (EMG) also throughout cycling hyperpnea. Minute ventilation, pattern, WoB, EMG comparable During cycling, cardiac BFI significantly greater [by +4.2 (2.6-5.9) L/min +4.9 (2.2-7.8) nmol/s, respectively] (P < 0.01). Muscle %StiO2 were, respectively, lower during scalene -3.8 (-6.4 to -1.2) nmol/s -6.6 (-8.2 -5.1)%], intercostal -1.4 (-2.4 -0.4) -6.0 (-8.6 -3.3)%], abdominal muscles -1.9 (-2.9 -0.8) -6.3 (-9.1 -3.4)%] 0.001). difference (scalene intercostal) was associated dyspnea (Borg CR10) scores (r = -0.54 r -0.49, P 0.05). These results suggest that COPD, 1) locomotor 2) insufficient adjustment may partly explain increased sensations dyspnea.NEW & NOTEWORTHY (BFI) three sustained levels neural drive COPD. demonstrated perfusion, as but not cycling. Insufficient

Language: Английский

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Impact of supine versus upright exercise on muscle deoxygenation heterogeneity during ramp incremental cycling is site specific

European Journal of Applied Physiology, Journal Year: 2021, Volume and Issue: 121(5), P. 1283 - 1296

Published: Feb. 11, 2021

Abstract Purpose We tested the hypothesis that incremental ramp cycling exercise performed in supine position ( S ) would be associated with an increased reliance on muscle deoxygenation (deoxy[heme]) deep and superficial vastus lateralis (VLd VLs, respectively) rectus femoris (RFs) when compared to upright U ). Methods 11 healthy men completed tests . Pulmonary $$\dot{V}$$ V ˙ O 2 was measured breath-by-breath; deoxy[heme] determined via time-resolved near-infrared spectroscopy VLd, VLs RFs. Results Supine overall change from baseline maximal : 38 ± 23 vs. 26 15 μM, P < 0.001) RFs 36 21 25 0.001), but not VLd 32 29 > 0.05). Conclusions The present study supports impaired balance between delivery utilization observed during is a regional phenomenon within muscles. Thus, defended its delivery/utilization against supine-induced reductions perfusion pressure. differential responses of these regions may explained by heterogeneity vascular metabolic control properties, perhaps related fiber type composition.

Language: Английский

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Relationship between muscle venous blood oxygenation and near-infrared spectroscopy: quantitative analysis of the Hb and Mb contributions

Journal of Applied Physiology, Journal Year: 2023, Volume and Issue: 134(5), P. 1063 - 1074

Published: March 17, 2023

Within the near-infrared spectroscopy (NIRS) signal, contribution from hemoglobin is indistinguishable that of myoglobin. A computation analysis indicates a linear relationship between muscle venous oxygen content and NIRS signals does not necessarily indicate negligible myoglobin to signal. reduced delivery increases The integrative approach proposed powerful way assist in interpreting elements which are derived.

Language: Английский

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Dissociation between exercise intensity thresholds: mechanistic insights from supine exercise

AJP Regulatory Integrative and Comparative Physiology, Journal Year: 2021, Volume and Issue: 321(5), P. R712 - R722

Published: Aug. 25, 2021

This study tested the hypothesis that respiratory compensation point (RCP) and breakpoint in deoxygenated [heme] [deoxy[heme]BP, assessed via near-infrared spectroscopy (NIRS)] during ramp incremental exercise would occur at same metabolic rate upright (U) supine (S) body positions. Eleven healthy men completed tests U S. Gas exchange was measured breath-by-breath time-resolved-NIRS used to measure deoxy[heme] vastus lateralis (VL) rectus femoris (RF). RCP (S: 2.56 ± 0.39, U: 2.86 0.40 L·min-1, P = 0.02) differed from deoxy[heme]BP VL (3.10 0.44 0.002), but not different S (2.70 0.50 0.15). RF for either position 2.34 0.48 2.76 0.53 > 0.05). However, between muscles both positions (P < 0.05), changes did relate ΔRCP (VL: r 0.55, 0.080, RF: 0.26, 0.44). The consistently preceded by a total[heme], was, turn, itself muscle surface electromyography (EMG). can be dissociated across and, therefore, do represent underlying physiological phenomenon. may, however, mechanistically related breakpoints total[heme] activity.

Language: Английский

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Effect of priming exercise and body position on pulmonary oxygen uptake and muscle deoxygenation kinetics during cycle exercise

Journal of Applied Physiology, Journal Year: 2020, Volume and Issue: 129(4), P. 810 - 822

Published: Aug. 6, 2020

We hypothesized that the performance of prior heavy exercise would speed pulmonary oxygen uptake (V̇o2) kinetics (i.e., as described by time constant, [Formula: see text]) and reduce amplitude muscle deoxygenation (deoxy[heme]) in supine (S) but not upright (U) body position. Seventeen healthy men completed heavy-intensity constant-work rate tests S U consisting two bouts 6-min cycling separated at 20 W. Pulmonary V̇o2 was measured breath breath; total deoxy[heme] were determined via time-resolved near-infrared spectroscopy (NIRS) three sites. Priming reduced text] (bout 1: 36 ± 10 vs. bout 2: 28 s, P < 0.05) 27 8 s 25 7 > 0.05). Deoxy[heme] increased after priming 25-28 μM 30-35 μM, 13-18 17-25 0.05), whereas baseline total[heme] enhanced 110-179 121-193 123-186 137-197 both U, likely indicating diffusive O2 delivery. However, observation response suggests reduction subsequent to related a combination intracellular utilization delivery.NEW & NOTEWORTHY Here we show are slower compared with position, an effect is associated skeletal After remained markedly elevated above observed during exercise. Hence, cannot be solely attributed delivery, enhancements must also contributory.

Language: Английский

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Larger splenic emptying correlate with slower EPOC kinetics in healthy men and women during supine cycling

European Journal of Applied Physiology, Journal Year: 2023, Volume and Issue: 123(10), P. 2271 - 2281

Published: June 4, 2023

Language: Английский

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Effect of Supplemental Oxygen on Physiological Responses to Exercise in Fibrotic Interstitial Lung Disease

Medicine & Science in Sports & Exercise, Journal Year: 2024, Volume and Issue: 56(11), P. 2093 - 2102

Published: July 11, 2024

ABSTRACT Purpose We studied the effect of O 2 supplementation on physiological response to exercise in patients with moderate severe interstitial lung disease (ILD). Methods Thirteen (age 66 ± 10 yr, 7 males) ILD (total capacity, 71% 22% predicted; carbon monoxide diffusion 44% 16% predicted) and 13 healthy individuals 50 17 were tested. performed symptom-limited cardiopulmonary tests constant work rate (WR) at 80% WR gas exchange threshold. Tests breathing room air (RA; 21% ) compared 30% . Oxygen uptake (V̇O kinetics calculated from test results. Results In group, peak WR, V̇O , threshold improved significantly when RA (mean SD, 75 26 vs 23 W, 4 15 mL·kg −1 ·min 932 245 854 232 mL·min ; P = 0.004, 0.001, 0.01, respectively). saturation (SpO %) was higher (97% 4% 88% 9%, 0.002). The time (tau) faster while (41 s) (52 14 s, 0.003). There a negative linear relation between tau SpO % ( r −0.76, 0.006) −0.68, 0.02). Conclusions Using clinically applicable level (30%) maximal, aerobic capacity patients, likely due increased blood content subsequently increasing delivery working muscles.

Language: Английский

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