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 materialThe online version of this article (doi:10.1007/s11357-014-9650-3) contains supplementary material, which is available to authorized users.
Highlights
In recent years, great emphasis has been placed on the identification of tissue biomarkers to determine vascular dysfunction early in the process of atherosclerosis
In the only available chronic exercise intervention study, we have previously shown that higher physical fitness levels are associated with higher retinal arteriolar-to-venular diameter ratio (AVR) and that regular endurance exercise induces arteriolar dilatation and venular constriction in middle-aged lean and obese individuals (Hanssen et al 2011)
Of the 32 study participants, 13 (41 %; eight seniors and five young adults) and 19 (59 %; nine seniors and 10 young adults) participants were randomly allocated to the exercise mode sequences Maximum treadmill test (MTT)-Submaximal 2-km treadmill test (SMTT)-control condition (CC) and MTT-CC-SMTT, respectively
Summary
Great emphasis has been placed on the identification of tissue biomarkers to determine vascular dysfunction early in the process of atherosclerosis. Smaller retinal arteriolar diameters are associated with incident coronary heart disease and larger retinal venular diameters are independently associated with increased risk of cardiovascular disease (Wong et al 2006b). It is of high clinical relevance and interest to examine how intervention strategies, such as dynamic exercise, affect retinal vessel diameters. In the only available chronic exercise intervention study, we have previously shown that higher physical fitness levels are associated with higher retinal AVR and that regular endurance exercise induces arteriolar dilatation and venular constriction in middle-aged lean and obese individuals (Hanssen et al 2011)
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