Effects of heat stress on ocular blood flow during exhaustive exercise

Tsukasa Ikemura, Naoyuki Hayashi

Research output: Contribution to journalArticle

4 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)172-179
Number of pages8
JournalJournal of Sports Science and Medicine
Volume13
Issue number1
Publication statusPublished - 2014 Mar
Externally publishedYes

Fingerprint

Hot Temperature
Arterioles
Nose
Blood Flow Velocity
Partial Pressure
Carbon Dioxide
Blood Vessels
Arterial Pressure
Heart Rate
Blood Pressure
Temperature

Keywords

  • Choroidal circulation
  • Exercise
  • Healthy subjects
  • Hyperthermia
  • Laser-speckle flowgraphy
  • Retinal circulation

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Effects of heat stress on ocular blood flow during exhaustive exercise. / Ikemura, Tsukasa; Hayashi, Naoyuki.

In: Journal of Sports Science and Medicine, Vol. 13, No. 1, 03.2014, p. 172-179.

Research output: Contribution to journalArticle

Ikemura, Tsukasa ; Hayashi, Naoyuki. / Effects of heat stress on ocular blood flow during exhaustive exercise. In: Journal of Sports Science and Medicine. 2014 ; Vol. 13, No. 1. pp. 172-179.
@article{890de330e816414085d79c6963c1cc35,
title = "Effects of heat stress on ocular blood flow during exhaustive exercise",
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.",
keywords = "Choroidal circulation, Exercise, Healthy subjects, Hyperthermia, Laser-speckle flowgraphy, Retinal circulation",
author = "Tsukasa Ikemura and Naoyuki Hayashi",
year = "2014",
month = "3",
language = "English",
volume = "13",
pages = "172--179",
journal = "Journal of Sports Science and Medicine",
issn = "1303-2968",
publisher = "Department of Sports Medicine, Medical Faculty of Uludag University",
number = "1",

}

TY - JOUR

T1 - Effects of heat stress on ocular blood flow during exhaustive exercise

AU - Ikemura, Tsukasa

AU - Hayashi, Naoyuki

PY - 2014/3

Y1 - 2014/3

N2 - 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.

AB - 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.

KW - Choroidal circulation

KW - Exercise

KW - Healthy subjects

KW - Hyperthermia

KW - Laser-speckle flowgraphy

KW - Retinal circulation

UR - http://www.scopus.com/inward/record.url?scp=84892847224&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84892847224&partnerID=8YFLogxK

M3 - Article

VL - 13

SP - 172

EP - 179

JO - Journal of Sports Science and Medicine

JF - Journal of Sports Science and Medicine

SN - 1303-2968

IS - 1

ER -