Lower body positive and negative pressure alter thermal and hemodynamic responses after exercise.
BACKGROUND
The purpose of this study was to determine the effect of upright lower body positive and negative pressure (LBPP/LBNP) application on the post-exercise thermal response. It was hypothesized that the application of LBPP would decrease core temperature secondary to increases in skin blood flow (SkBF) and sweating, whereas the application of LBNP would maintain core temperature secondary to attenuated SkBF and sweating responses.


METHODS
There were six subjects who randomly underwent each of the following treatments in the upright posture, separated by a minimum of 48 h: 1) +45 mmHg LBPP; 2) -20 mmHg LBNP; or 3) no pressure for 45 min after performing 15 min of cycle ergometry exercise at 70% of their VO2peak. Measurements included mean arterial pressure (MAP), heart rate (HR), cardiac output (Q), stroke volume (SV), total peripheral resistance (TPR), mean skin temperature (Tsk), mean heat flux, esophageal temperature (Tes), SkBF, and sweat rate.


RESULTS
After the application of LBPP, we observed a significantly greater decrease in core temperature relative to the LBNP and control conditions (p < 0.001). This was accompanied by increases in SkBF, sweating, and heat flux (p < 0.05), all of which were higher than the LBNP and control conditions. Core temperature, SkBF, sweating, and heat flux in the LBNP and control conditions were not different from each other. LBPP promoted the restoration of hemodynamics while LBNP and control prolonged the post-exercise hemodynamic state.


CONCLUSIONS
We conclude that during recovery from exercise in the upright seated posture, core temperature recovery is affected by compromised SkBF and sweating secondary to nonthermal cardiovascular influences.
Journeay
W Shane
WS
Laboratory of Human Bioenergetics and Environmental Physiology, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada.
Reardon
Francis D
FD
Jean-Gilles
Sartre
S
Martin
C Ryan
CR
Kenny
Glen P
GP
D000328:Adult; D001794:Blood Pressure; D001831:Body Temperature / Q000502:physiology*; D001833:Body Temperature Regulation; D002302:Cardiac Output; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D011187:Posture; D011312:Pressure; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply; D013318:Stroke Volume