Effects of Physical Effort on Neuroretinal Function in Athletes and Non-Athletes: An Electroretinographic Study

Abstract

Physical exertion may disturb retinal function. We wondered whether different levels of physical performance could affect the plot of neuroretinal activity after dynamic exercise in healthy subjects. The aim of our study was to estimate the effect of increasing intensity physical exercise on retinal activity in 2 groups: athletes (n=10) and non-athletes (n=10). We analyzed the amplitude and implicit time of b-wave electroretinogram (ERG) responses for a photopic white 30-Hz flicker stimulus. Using a cycloergometer, 3 10-minute effort tests with increasing intensity were performed. Each participant was attributed an individual workload value (W) below his lactate threshold (40% VO2max), at his lactate threshold (65%-75% VO2max), and above his lactate threshold (80% VO2max). Five ERG recordings were taken: before the efforts (first), immediately after the 3 consecutive efforts (second to fourth), and 1 hour after the last effort (fifth). After the first effort, in both groups we observed a statistically significant increase in b-wave amplitude (p<0.05), and in non-athletes a decrease in implicit time of b-wave (p<0.05). After the last effort, we observed a decreased b-wave amplitude in non-athletes, whereas in athletes the amplitude remained at a high level. Physical effort significantly differentiated the plot of b-wave amplitude changes between athletes and non-athletes. These findings suggest that strenuous physical effort may disturb signal transfer in the inner retinal layer in non-athletic subjects. The ERGs may be used as a neurophysiologic indicator in defining the cardiovascular training status of an athlete.