Postexercise thermal and cardiovascular responses following fast and slow heating exercise protocols

From National Research Council Canada

Author	Search for: Kenny, Glen P.; Search for: Wright, Heather E.; Search for: Friesen, Brian J.
Format	Text, Address
Conference	Experimental Biology 2011, Apr. 9th-13th, 2011, Washington, D.C.
Abstract	Exercise-induced hyperthermia can result in significant cardiovascular and thermoregulatory disturbances which can persist for a prolonged period. However, it is unclear if this response differs as a function of the time to reach hyperthermia. Therefore, we compared cardiovascular and thermoregulatory responses of subjects rendered hyperthermic by either a slow heating (SH) or fast heating (FH) exercise protocol performed in the heat (40°C). On separate days, 7 subjects either walked (4 mph, 2% grade, SH) or ran (7.5 mph, 2% grade, FH) on a treadmill until rectal temperature (Tre) increased to 39.5°C. Subjects then rested in the upright seated position in thermoneutral conditions (30°C) until Tre returned to 38.0°C. Heart rate (HR) and mean arterial pressure (MAP) were assessed continuously. Change in plasma volume (ΔPV) from baseline rest was measured at end of recovery. The time to reach Tre of 39.5°C was significantly longer during SH (76.5±6.5 min) compared to FH (35.5±3.3 min, p<0.05). However, the time to reach the Tre recovery of 38.0°C was significantly greater during FH compared to SH (82.5±9.2 vs. 56.2±6.5 min, p<0.05). Despite a longer recovery during FH, a similar reduction in MAP (FH:−9.6±1.7 vs. SH: −10.1±3.4 mmHg) was observed at end-recovery which was paralleled by similar elevations in HR (FH:83±2 vs. SH:87±5 bpm). Further, ΔPV was also similar between conditions (FH: −5.1±1.9 vs. SH: −5.8±2.8%) albeit reduced from end-exercise values (FH:9.0±1.1% vs. SH:11.8±1.5%,p<0.05). Different exercise-intensity ramping protocols performed to a similar level of thermal strain influence core temperature recovery time but not the level of cardiovascular strain.
Publication date	2011-04-12
Publisher	Federation of American Societies for Experimental Biology
In	The FASEB Journal 25, no. Supplement 1, 105.3.
Language	English
Peer reviewed	Yes
NRC publication	This is a non-NRC publication "Non-NRC publications" are publications authored by NRC employees prior to their employment by NRC.
NPARC number	23001381
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Record identifier	867c98bd-2f0a-4cbb-875d-9039ccc5db80
Record created	2017-01-31
Record modified	2020-03-03

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