Moderate whole body heating attenuates the exercise pressor reflex responses in older humans.
Am J Physiol Regul Integr Comp Physiol
; 320(5): R757-R769, 2021 05 01.
Article
in En
| MEDLINE
| ID: mdl-33789459
ABSTRACT
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 of â¼0.4°C-0.5°C) or limb heating on sympathetic and cardiovascular responses to exercise in older healthy humans remain unclear. We examined the muscle sympathetic nerve activity (MSNA), mean arterial blood pressure (MAP), and heart rate (HR) in 14 older (62 ± 2 yr) healthy subjects during fatiguing isometric handgrip exercise and postexercise circulatory occlusion (PECO). The protocol was performed under normothermic, moderate WBH, and local limb (i.e., forearm) heating conditions during three visits. During the mild WBH stage (increase in Tcore of <0.3°C), HR increased, whereas BP and MSNA decreased from baseline. Under the moderate WBH condition (increase in Tcore of â¼0.4°C), BP decreased, HR increased, and MSNA was unchanged from baseline. Compared with the normothermic trial, the absolute MAP during fatiguing exercise and PECO was lower during the WBH trial. Moreover, MSNA and MAP responses (i.e., changes) to fatiguing exercise were also less than those seen during the normothermic trial. Limb heating induced a similar increase in forearm muscle temperature to that seen in the WBH trial (â¼0.7°C-1.5°C). Limb heating did not alter resting MAP, HR, or MSNA. The MSNA and hemodynamic responses to exercise in the limb heating trial were not different from those in the normothermic trial. These data suggest that moderate WBH attenuates MSNA and BP responses to exercise in older healthy humans.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Reflex
/
Aging
/
Muscle, Skeletal
/
Hand Strength
/
Heating
Limits:
Adult
/
Aged
/
Humans
/
Male
Language:
En
Journal:
Am J Physiol Regul Integr Comp Physiol
Journal subject:
FISIOLOGIA
Year:
2021
Document type:
Article