10.1152/physiolgenomics.00169.2022

Vollständiger Abstract

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Older adults exhibit heightened vulnerability to heat-related morbidity, yet it remains unclear whether short-term heat acclimation modifies integrative physiological stress responses in aging. We tested whether seven days of passive heat acclimation via warm water immersion alters basal concentrations and acute exercise-heat stress responses of biomarkers reflecting fluid regulation, gastrointestinal epithelial integrity, renal stress, and inflammation in older males. Twelve habitually active older males (median [IQR] age: 68 [64-73] years; V̇O 2 peak: 34.1 [29.4-36.1] mL O 2 ·kg -1 ·min-1) completed an exercise-heat stress test before and after seven consecutive days of warm water immersion (~40°C), with rectal temperature maintained at ~38.5°C for the final 60 min. Blood samples were collected before and after each exercise-heat stress test and analysed using linear mixed-effects models (Day x Time). Repeated warm water immersion increased resting renin by 68% [95% CI: 29, 120; <i>P</i><0.001], while neutrophil gelatinase-associated lipocalin and lipopolysaccharide binding protein decreased by 24% [-40, -4; <i>P</i>=0.023] and 22% [-37, -3; <i>P</i>=0.026] respectively. Exercise heat stress increased aldosterone by 45% [12, 87%, <i>P</i>=0.004], renin by 41% [8, 84%, <i>P</i>=0.01], intestinal fatty acid-binding protein by 52% [26, 85%, <i>P</i><0.001], and plasma osmolality by 5.6% [2.5, 8.7%, <i>P</i><0.001]. However, there was no day x time interaction for any biomarker (all <i>P</i>>0.05), indicating that seven days of warm water immersion did not alter the magnitude of the exercise heat stress response. Short-term passive heat acclimation in older males induces selective fluid-regulatory endocrine adaptations consistent with preserved renin-angiotensin-aldosterone system plasticity, while gastrointestinal and renal stress responses to exercise-heat exposure remain unchanged.

Abstract: PubMed · Datensatz