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Exercise Pressor Reflex is Attenuated during Moderate Whole‐Body Heating in Older Humans
Author(s) -
Cui Jian,
Gao Zhaohui,
Blaha Cheryl,
Luck Jonathan,
Brandt Kristen,
Sinoway Lawrence
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.01727
Subject(s) - medicine , isometric exercise , heart rate , blood pressure , hemodynamics , reflex , anesthesia , mean arterial pressure , cardiology
Prior reports show that whole‐body heat stress attenuates the pressor response to exercise in young healthy subjects. The effects of moderate whole‐body heating (WBH, e.g. increase in internal temperature Tcore ~0.4‐0.5 °C) on sympathetic and cardiovascular responses to exercise in older healthy humans remains unclear. We examined muscle sympathetic nerve activity (MSNA), mean arterial blood pressure (MAP) and heart rate (HR) in 14 older (62 ± 7 yrs. mean ± SD) healthy subjects during fatiguing isometric handgrip exercise and post exercise circulatory occlusion (PECO). The protocol was performed under normothermic and moderate WBH conditions during 2 visits. Under the moderate WBH condition (ΔTcore ~0.4 ± 0.1 °C), MAP decreased (90.0 ± 6.6 to 86.4 ± 7.1 mmHg), HR increased (60.8 ± 7.9 to 71.7 ± 9.7 beats/min), while MSNA was unchanged (34.7 ± 9.2 to 37.5 ± 15.4 bursts/min) from the baseline before heating. Hemodynamic variables and MSNA did not change significantly during the time control period in the normothermic trial. Compared with the normothermic trial, the absolute MAP during fatiguing exercise (102.7 ± 8.5 vs. 117.2 ± 11.4 mmHg) and PECO (98.2 ± 8.9 vs. 113.9 ± 12.5 mmHg) were lower during the WBH trial. Moreover, MSNA (Δ8.4 ± 6.5 vs. Δ14.0 ± 7.2 bursts/min) and MAP (Δ16.5 ± 7.5 vs. Δ23.2 ± 8.2 mmHg) responses (i.e. changes) to fatiguing exercise were also less than those seen during the normothermic trial. These data suggest that moderate WBH attenuates reflex exercise pressor responses in older healthy humans. Further studies are needed to examine if WBH can attenuate exercise pressor responses in patients with cardiovascular diseases.