Article

Effects of dynamic exercise and its intensity on ocular blood flow in humans

Institute of Health Science and Graduate School of Human-Environment Studies, Kyushu University, Kasuga, Fukuoka, Japan.
Arbeitsphysiologie (Impact Factor: 2.19). 03/2011; 111(10):2601-6. DOI: 10.1007/s00421-011-1880-9
Source: PubMed

ABSTRACT

Visual performance is impaired when the ocular blood flow decreases, indicating that ocular blood flow plays a role in maintaining visual performance during exercise. We examined the ocular blood flow response to incremental cycling exercise to test the hypothesis that ocular blood flow is relatively stable during dynamic exercise because of its autoregulatory nature. The blood flow in the inferior and superior temporal retinal arterioles (ITRA and STRA, respectively) and retinal and choroidal vessels (RCV), mean arterial pressure, and heart rate (HR) were measured at rest and during leg cycling in nine young and healthy subjects (26 ± 5 years, mean ± SD). Ocular blood flow was measured by laser speckle flowmetry. The exercise intensity was incremented by 30 W every 3 min until the subject was unable to maintain a position appropriate for measuring ocular blood flow. Blood flow data obtained during cycling exercise were categorized based on HR as follows: <100, 100-120, and >120 bpm. Blood flow in the RCV increased with the exercise intensity: by 16 ± 8, 32 ± 13, and 40 ± 19% from baseline, respectively. However, blood flow and vascular conductance in the ITRA and STRA did not change significantly with exercise. These findings demonstrate for the first time that ocular blood flow increases in the retina and choroid, but not in the arterioles, with increasing exercise intensity during dynamic exercise.

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    • "In response to the increase in perfusion pressure, a vasoconstriction of retinal arteries and veins occurs, inducing an increase in vascular resistance. This compensatory autoregulation, also known as myogenic response, is responsible for the maintenance of normal blood flow in central retinal arteries and veins during dynamic exercise (Harris et al. 1996; Iester et al. 2007; Hayashi et al. 2011). In seniors, the retinal arterial myogenic response induced by a systemic blood pressure increase during isometric resistance training has been shown to be decreased compared to younger adults (Jeppesen et al. 2004). "
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    ABSTRACT: Alterations of retinal vessel diameters are associated with increased cardiovascular risk. We aimed to investigate changes in retinal vessel diameters in response to acute dynamic exercise of different intensities and whether these changes are age dependent. Seventeen healthy seniors (median (IQR) age 68 (65, 69) years) and 15 healthy young adults (median (IQR) age 26 (25, 28) years) first performed a maximal treadmill test (MTT) followed by a submaximal treadmill test (SMTT) and a resting control condition in randomised order. Central retinal arteriolar (CRAE) and central retinal venular (CRVE) diameter equivalents were measured before as well as 5 (t5) and 40 (t40) minutes after exercise cessation using a static retinal vessel analyser. Both exercise intensities induced a significant dilatation in CRAE and CRVE at t5 compared to the control condition (P < 0.001). At t40, the mean increase in CRAE and CRVE was greater for MTT compared to that for SMTT (CRAE 1.7 μm (95 % confidence interval (CI) −0.1, 3.6; P = 0.061); CRVE 2.2 μm (95 % CI 0.4, 4.1; P = 0.019)). However, the estimated difference at t5 between seniors and young adults in their response to MTT compared to SMTT was 5.3 μm (95 % CI 2.0, 8.5; P = 0.002) for CRAE and 4.1 μm (95 % CI −0.4, 8.6; P = 0.076) for CRVE. Wider arteries and veins after maximal versus submaximal exercise for seniors compared to young adults suggest that myogenic vasoconstriction in response to exhaustive exercise may be reduced in seniors. Age-related loss of vascular reactivity has clinical implications since the arteriolar vasoconstriction protects the retinal capillary bed from intraluminal pressure peaks. Electronic supplementary material The online version of this article (doi:10.1007/s11357-014-9650-3) contains supplementary material, which is available to authorized users.
    Full-text · Article · Apr 2014 · Age
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    • "The pressor response could be attenuated by heat stress during exhaustive exercise. Changes in the MAP affected the choroidal circulation (Hayashi et al., 2011b; Ikemura et al., 2011), and although the retinal circulation is affected less by MAP fluctuations due to the existence of autoregulation , both ocular blood flows may be influenced by attenuation of the pressor response during exhaustive exercise in the presence of heat stress. Ikemura et al. (2012b) demonstrated that hypocapnia decreases the blood flow in both ocular blood flows during exhaustive exercise, in spite of retinal autoregulation. "
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    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 degrees C (control condition) and 35 degrees 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 degrees C and 35 degrees 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 degrees C and 35 degrees 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.
    Full-text · Article · Feb 2014 · Journal of sports science & medicine
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    • "In response to the increase in perfusion pressure, a vasoconstriction of retinal arteries and veins occurs, inducing an increase in vascular resistance. This compensatory autoregulation, also known as myogenic response, is responsible for the maintenance of normal blood flow in central retinal arteries and veins during dynamic exercise (Harris et al. 1996; Iester et al. 2007; Hayashi et al. 2011). In seniors, the retinal arterial myogenic response induced by a systemic blood pressure increase during isometric resistance training has been shown to be decreased compared to younger adults (Jeppesen et al. 2004). "

    Full-text · Article · Sep 2013 · Artery Research
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