Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
Views
6170
Download
8
from September 2014
 
©Journal of Sports Science and Medicine ( 2014 ) 13 , 172 - 179

Research article
Effects of Heat Stress on Ocular Blood Flow During Exhaustive Exercise
Tsukasa Ikemura1,2, Naoyuki Hayashi2, 
Author Information
1 Graduate School of Human-Environment Studies, Kyushu University, Kasuga, Fukuoka, Japan
2 Graduate School of Decision Science and Technology, Tokyo Institute of Technology, Ookayama, Meguro, Japan

Naoyuki Hayashi
✉ Graduate School of Decision Science and Technology, Tokyo Institute of Technology, Ookayama, Meguro, 152-8552, Japan
Email: naohayashi@hum.titech.ac.jp
Publish Date
Received: 05-09-2013
Accepted: 23-10-2013
Published (online): 20-01-2014
Share this article
 
 
ABSTRACT

The hypothesis that heat stress reduces the ocular blood flow response to exhaustive exercise was tested by measuring ocular blood flow, blood pressure, and end- tidal carbon dioxide partial pressure (PETCO2) in 12 healthy males while they performed cycle ergometer exercise at 75% of the maximal heart rate at ambient temperatures of 20°C (control condition) and 35°C (heat condition), until exhaustion. The blood flows in the retinal and choroidal vasculature (RCV), the superior temporal retinal arteriole (STRA) and the superior nasal retinal arteriole (SNRA) were recorded at rest and at 6 and 16 min after the start of exercise period and at exhaustion [after 16 ± 2 min (mean ± SE) and 24 ± 3 min of exercise in the heat and control condition, respectively]. The mean arterial pressure at exhaustion was significantly lower in the heat condition than in the control condition at both 16 min and exhaustion. The degree of PETCO2 reduction did not differ significantly between the two thermal conditions at either 16 min or exhaustion. The blood flow velocity in the RCV significantly increased from the resting baseline value at 6 min in both thermal conditions (32 ± 6% and 25 ± 5% at 20°C and 35°C, respectively). However, at 16 min the increase in RCV blood flow velocity had returned to the resting baseline level only in the heat condition. At exhaustion, the blood flows in the STRA and SNRA had decreased significantly from the resting baseline value in the heat condition (STRA: -19 ± 5% and SNRA: -30 ± 6%), and SNRA blood flow was lower than that in the control condition (-14 ± 6% vs -30 ± 6% at 20°C and 35°C, respectively), despite the finding that both thermal conditions induced the same reductions in PETCO2 and vascular conductance. These findings suggested that the heat condition decreases or suppresses ocular blood flow via attenuation of pressor response during exhaustive exercise.

Key words: Hyperthermia, exercise, healthy subjects, retinal circulation, choroidal circulation, laser-speckle flowgraphy


           Key Points
  • The ocular (retinal and choroidal) blood flow response to exhaustive exercise with heat stress is unknown.
  • We hypothesized that the heat stress decreases ocular blood flow response to exhaustive exercise, since cerebral flow, which is regulated similarly to ocular flow, was reported to decrease during heat stress.
  • To test this hypothesis, ocular blood flow was measured during exhaustive exercise at 20°C (control condition) and 35°C (heat condition).
  • At exhaustion in the heat condition, the ocular flow response was suppressed or decreased with an attenuated pressor response.
  • It is suggested that the heat condition decreases or suppresses the ocular blood flow to exhaustive exercise via attenuation of pressor response.
 
 
Home Issues About Authors
Contact Current Editorial board Authors instructions
Email alerts In Press Mission For Reviewers
Archive Scope
Supplements Statistics
Most Read Articles
  Most Cited Articles
 
    
 
JSSM | Copyright 2001-2019 | All rights reserved. | LEGAL NOTICES | Publisher

It is forbidden the total or partial reproduction of this web site and the published materials, the treatment of its database, any kind of transition and for any means, either electronic, mechanic or other methods, without the previous written permission of the JSSM.

This work is licensed under a Creative Commons License Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.