Purpose: Hypoxic acclimation enhances convective oxygen delivery to the muscles. Heat acclimation-elicited thermoregulatory benefits have been suggested not to be negated by adding daily exposure to hypoxia. Whether concomitant acclimation to both heat and hypoxia offers a synergistic enhancement of aerobic performance in thermoneutral or hot conditions remains unresolved.
Methods: Eight young males ([Formula: see text]: 51.6 ± 4.6 mL min kg) underwent a 10-day normobaric hypoxic confinement (FO = 0.14) interspersed with daily 90-min normoxic controlled hyperthermia (target rectal temperature: 38.5 °C) exercise sessions. Prior to, and following the confinement, the participants conducted a 30-min steady-state exercise followed by incremental exercise to exhaustion on a cycle ergometer in thermoneutral normoxic (NOR), thermoneutral hypoxic (FO = 0.14; HYP) and hot (35 °C, 50% relative humidity; HE) conditions in a randomized and counterbalanced order. The steady-state exercise was performed at 40% NOR peak power output (W) to evaluate thermoregulatory function. Blood samples were obtained from an antecubital vein before, on days 1 and 10, and the first day post-acclimation.
Results: [Formula: see text] and ventilatory thresholds were not modified in any environment following acclimation. W increased by 6.3 ± 3.4% in NOR and 4.0 ± 4.9% in HE, respectively. The magnitude and gain of the forehead sweating response were augmented in HE post-acclimation. EPO increased from baseline (17.8 ± 7.0 mIU mL) by 10.7 ± 8.8 mIU mL on day 1 but returned to baseline levels by day 10 (15.7 ± 5.9 mIU mL).
Discussion: A 10-day combined heat and hypoxic acclimation conferred only minor benefits in aerobic performance and thermoregulation in thermoneutral or hot conditions. Thus, adoption of such a protocol does not seem warranted.
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http://dx.doi.org/10.1007/s00421-019-04215-5 | DOI Listing |
Int J Biol Sci
January 2025
Department of Otolaryngology Head and Neck Surgery/Deep Underground Space Medical Center, West China Hospital, Sichuan University, Chengdu, China.
Heat acclimation (HA) is an evolutionarily conserved trait that enhances tolerance to novel stressors by inducing heat shock proteins (HSPs). However, the molecular mechanisms underlying this phenomenon remain elusive. In this study, we established a HA mouse model through intermittent heat stimulation.
View Article and Find Full Text PDFPhysiol Rep
December 2024
Clinical Laboratory Diagnostic Center, General Hospital of Xinjiang Military Command, Urumqi, Xinjiang, China.
Plateau acclimatization involves adaptive changes in the body's neurohumoral regulation and metabolic processes due to hypoxic conditions at high altitudes. This study utilizes Olink targeted proteomics to analyze serum protein expression differences in Han Chinese individuals acclimatized for 6 months-1 year at 4500 and 5300 m altitudes, compared to those residing at sea level. The objective is to elucidate the proteins' roles in tissue and cellular adaptation to hypoxia.
View Article and Find Full Text PDFFront Physiol
December 2024
Department of Cardiology, The General Hospital of Western Theater Command, Chengdu, China.
Background: The low-pressure, hypoxic environment characteristic of high-altitude regions significantly affects the cardiovascular and autonomic nervous system functions of individuals, consequently impairing their sleep quality. Heart rate variability, a non-invasive indicator of autonomic nervous system activity and balance within the cardiovascular system, has not been thoroughly investigated in terms of its patterns during acclimatization and de-acclimatization phases for individuals traveling to and residing in high-altitude areas and its relationship with sleep stability.
Methods: Data was collected from 22 medical staff members who traveled from Chengdu to Yecheng, with measurements taken before leaving Chengdu, 1 week in Yecheng, 3 months in Yecheng, and 1 week after returning to Chengdu.
Open Access J Sports Med
December 2024
Department of Exercise Physiology, College of Sport Sciences and Physical Activity, King Saud University, Riyadh, Saudi Arabia.
Background: Un-acclimatized individuals may experience acute altitude illness. Thus, the current study investigated the impact of short-term intermittent normobaric hypoxia (NH) combined with light exercise on the acclimatization of cardiorespiratory function to altitude in inactive adults.
Methods: This quasi-experimental study recruited 10 inactive university students (age: 26.
PeerJ
December 2024
Air Force Clinical College; The Fifth School of Clinical Medicine, Anhui Medical University, Hefei, China.
Background: The impact of acute mountain sickness (AMS) on individuals ascending to plateaus, soon after exposure to high altitudes, is well-documented. However, the specific relationship between AMS and alterations in blood parameters remains unclear.
Methods: A total of 40 healthy volunteers were recruited.
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