title: Postexercise heat loss and hemodynamic responses during head-down tilt are similar between genders.
abstract: OBJECTIVE
  We evaluated the hypothesis that during recovery from dynamic exercise in the 15 degrees head-down tilt (HDT) position, the attenuation of the fall in mean arterial pressure (MAP), cutaneous vascular conductance (CVC), and sweat rate, and the augmentation of the rate of esophageal temperature (T(es)) decay relative to the upright seated (URS) posture, would be different between males and females.
  
  
  METHODS
  Fourteen subjects (seven males, seven females) performed two experimental protocols: 1) 15 min of cycle ergometry at 75% VO2peak and then 60 min of recovery in the URS posture; or 2) 15 min of cycle ergometry at 75% VO2peak and then 60 min of recovery in the 15 degrees HDT position. Mean skin temperature, Tes, CVC, sweat rate, cardiac output (CO), stroke volume (SV), heart rate (HR), total peripheral resistance (TPR), and MAP were recorded at baseline; end of exercise; 2 min, 5 min, 8 min, 12 min, 15 min, and 20 min after exercise; and every 5 min until the end of recovery (60 min).
  
  
  RESULTS
  During recovery from exercise, we observed significantly greater values for MAP, CVC, and sweat rate with HDT in comparison with the URS recovery posture (P <or= 0.05). The magnitude of these responses to HDT did not differ between genders, and a significantly lower T(es) was subsequently observed with HDT for the duration of recovery (P <or= 0.05) for both males and females. In the URS posture, females showed a greater decrease of postexercise MAP than did males (P <or= 0.05). At the end of 60 min of recovery, T(es) remained significantly elevated above baseline with the URS recovery posture (P <or= 0.05). With HDT, T(es) returned to baseline after 20 min.
  
  
  CONCLUSIONS
  HDT attenuates the reductions in MAP, CVC, and sweat rate observed after exercise in a gender-independent manner, and this likely is attributable to a nonthermal baroreceptor influence.
authors.affiliation: Laboratory of Human Bioenergetics and Environmental Physiology, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada.
authors.forename: W Shane
authors.initials: WS
authors.lastname: Journeay
authors.forename: Ollie
authors.initials: O
authors.lastname: Jay
authors.forename: Natalie H
authors.initials: NH
authors.lastname: McInnis
authors.forename: Emily
authors.initials: E
authors.lastname: Leclair
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000328:Adult; D001833:Body Temperature Regulation / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D018475:Head-Down Tilt / Q000502:physiology*; D006801:Humans; D007022:Hypotension; D008297:Male; D009864:Ontario; D005082:Physical Exertion / Q000502:physiology; D012881:Skin Temperature / Q000502:physiology; D013542:Sweat / Q000502:physiology