EVALUATION OF RETINAL MICROCIRCULATION IN TRAINED AND UNTRAINED SUBJECTS: COMPARISON BEFORE AND AFTER EXERCISE

Objective: Physical exercise is considered an important tool for cardiovascular mortality reduction and cardiovascular prevention. Our aim was to assess retinal microcirculation in trained subjects (ATHLETES) in comparison with untrained subjects (NAIVE) after maximal isokinetic exercise. Design and method: Twenty four healthy male subjects were recruited: 12 trained subjects (ATHLETES) and 12 untrained healthy subjects (NAÏVE). A clinical evaluation and the International Physical Activity Questionary (IPAQ) was performed in all participants. Retinal arteriolar morphology and function was assessed by Adaptive Optics at rest and 20 minutes after a maximal isokinetic leg extension exercise. Internal and external arteriolar diameter, venular diameter, wall thickness, Wall-to-Lumen Ratio (WLR), Wall Cross-Sectional Area (WCSA), Arteriole-to-Venule Ratio (AVR) and flicker light induced arteriolar dilatation (aFID) were measured. The maximum voluntary isometric contraction (MVIC, expressed in kg) generated in the exercise protocol was also measured. Results: The two groups differed in terms of BMI (p < 0.05), resting heart rate (p < 0.05), difference in METs consumed during intense activities according to IPAQ (p < 0.001) and the MVIC (p < 0.001). No statistically significant differences were observed between the two groups in the retinal arteriole parameters in basal conditions, although a trend of higher average values of arteriolar diameters was observed in the ATHLETES group. Twenty minutes after exercise, a statistically significant increase in the internal and external arteriolar diameter (p < 0.05) and in the venular diameter (p < 0.01) with a reduction in WLR (p<0.05) was observed compared to baseline in both the groups. aFID did not show statistically significant differences in the two groups. However, in the ATHLETES group, a trend of lower aFID before exercise and higher after exercise was noted, compared to the NAIVE group. Conclusions: Physical exercise induce an acute vasodilation of retinal vessels possibly mediated at least in part by increase in nitric oxide confirming its beneficial effect. The slightly larger arteriolar diameters in the ATHLETES group could suggest the existence of a eutrophic remodeling, a condition described as athlete’s artery, a physiological dilation of the basal arterial diameters in response to regular training.