Directional sensitivity analysis of the cerebral pressure-flow relationship during normothermia and moderate hyperthermia | Journal of Applied Physiology | American Physiological Society

Dynamic cerebral autoregulation (dCA) reacts differently when mean arterial pressure (MAP) increases versus decreases (i.e. directional sensitivity). While heat stress alters dCA, its influence on directional sensitivity remains unclear. This analysis investigated the impact of moderate hyperthermia on the directional sensitivity in the cerebral pressure‐flow relationship. Ten healthy participants (7 males; age: 37 ± 12 yrs.; body mass: 75 ± 9 kg) underwent 6 min of oscillatory lower body negative pressure (OLBNP) to induce large MAP fluctuations, at 0.03 and 0.10 Hz under normothermic and moderately hyperthermic conditions (+1.0°C increase in core temperature) induced via a water‐perfused suit. We calculated changes in middle cerebral artery mean blood velocity (MCAv) per alterations to MAP to compute absolute and relative ratios adjusted for time intervals during each OLBNP‐induced MAP increases (ΔMCAvT/ΔMAPTINC; %MCAvT/%MAPTINC) and decreases (ΔMCAvT/ΔMAPTDEC; %MCAvT/%MAPTDEC). Thereafter, we compared average absolute and relative ratios. There was no main effect of MAP direction on ΔMCAvT/ΔMAPT or %MCAvT/%MAPT during either 0.03 Hz (P=0.291, P=0.281) or 0.10 Hz (P=0.295, P=0.178) OLBNP. Regardless of MAP direction, ΔMCAvT/ΔMAPTINC (0.65 ± 0.17 vs 0.84 ± 0.22 cm. s−1/mmHg), ΔMCAvT/ΔMAPTDEC (0.70 ± 0.15 vs 0.85 ± 0.18 cm. s−1/mmHg) (thermal state: P=0.009), %MCAvT/%MAPTINC (0.92 ± 0.22 vs 1.33 ± 0.60), and %MCAvT/%MAPTDEC (1.01 ± 0.27 vs 1.30 ± 0.51) (thermal state: P=0.001) were lower in hyperthermia at 0.03 Hz OLBNP. Regardless of thermal states, these findings suggest an absence of dCA directional sensitivity. Reduced directional sensitivity metrics during hyperthermia may indicate more efficient dCA at very low frequency.

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Sex differences in the physiological and perceptual responses to face masks during exercise | Journal of Applied Physiology | American Physiological Society

Despite consistent evidence that face masks (FMs) increase dyspnea during exercise, few studies have examined the sex differences in the physiological and perceptual responses to FMs. In a randomized,...

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Diaphragm blood flow: new avenues for human translation | Journal of Applied Physiology | American Physiological Society

The rhythmic contraction of the diaphragm facilitates continuous pulmonary ventilation essential for life. Adequate blood flow to the diaphragm is critical to continuously support contractile function...

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Effect of condensed heat acclimation on thermophysiological adaptations, hypoxic cross-tolerance, exercise performance, and deacclimation | Journal of Applied Physiology | American Physiological Socie...

Short duration heat acclimation (HA) (≤5 daily heat exposures) elicits incomplete adaptation compared with longer interventions, possibly due to the lower accumulated thermal “dose.” It is unknown if ...

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Physiological Resilience: What Is It and How Might It Be Trained?

Physiological resilience has recently been recognized as an additional factor that influences endurance exercise performance. It has thus been incorporated into a modified, contemporary version of “t...

onlinelibrary.wiley.com

Muscle oxygenation and local blood volume difference between respiratory and skeletal muscles during preparatory and maximal dry static apnea in breath-hold divers

During either a static or dynamic apnea, oxygen is delivered to vital organs, i.e., the brain and heart, and there is a compensatory reduction of oxyg…

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Neuromuscular Fatigue Induced by Cycling at a Fixed Level of Perceived Effort: Effects of Different Purported Hypoxic Methods

We compared neuromuscular fatigue induced by cycling at a fixed perceived effort in normoxic condition (NOR) and three purported hypoxia modalities: systemic hypoxia (SyH, FiO2 = 0.13), blood flow re...

onlinelibrary.wiley.com

Physiological rhythms and metabolic regulation: Shining light on skeletal muscle

Metabolic regulation is essential for maintaining homeostasis in response to fluctuating dietary nutrient availability. In this review, we explore how metabolic health can be affected by the temporal...

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Nocturnal pulse oxygen saturation dynamics at simulated high altitude: Predictive value for acute mountain sickness in healthy men born pre‐term

The physiological sequelae of pre-term birth might influence the responses of this population to hypoxia. Moreover, identifying variables associated with development of acute mountain sickness (AMS) ...

physoc.onlinelibrary.wiley.com

Training Elite Athletes: 50 Years of Thinking About Practice and Research for Endurance Sports

This essay summarizes and integrates my experiences and observations—starting in the middle 1970s—as an athlete, scientist interested in human performance, biomedical researcher, and “expert,” who so...

onlinelibrary.wiley.com

Research directions in thermoregulation during exercise in extreme environments

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Practice and Science: Why Both Matter

"It's better to be consistently wrong than right once in a while" - Chuckie V

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UAE Team Emirates confirm squad have stopped using carbon monoxide rebreathing

'It was an exercise that we conducted over 18 months... We finished that process now' says Jeroen Swart

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Canadian Science Publishing

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The effect of repeated hot water immersion on vascular function, blood pressure and central haemodynamics in individuals with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is characterised by endothelial dysfunction, leading to increased risk of cardiovascular disease. Emerging evidence su…

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