The Effects Of Jogging On Contrast Sensitivity

Contrast sensitivity is a measurement of your eyes' ability to distinguish between different objects in a scene, typically ones that are overlapping, poorly outlined and similarly colored. While someone with high contrast sensitivity may be able to read your expressions in very low light, someone with low contrast sensitivity may have difficulties doing so under normal conditions. With a variety of physical and mental benefits, it may come as no surprise that regular physical activity, such as jogging, may help to improve contrast sensitivity.

Stress and Vision

Your sympathetic nervous system is activated by stress, causing a cascade of different physiological effects known as the "fight or flight" response. In addition to shutting down or slowing down nonessential physical functions, sympathetic nervous activity prepares you to fight or flee by increasing the size of your pupils and improving your peripheral vision. Jogging, which is treated as a form of stress by your body, may activate this fight or flight response, thus increasing your pupil size. This increased pupil size improves your contrast sensitivity under all light conditions, according to the results of a 2007 study by Jose Alfonso and colleagues at the Fernandez-Vega Ophthalmological Institute in Olviedo, Spain.

Athletes and Nonathletes

Compared with people who are not physically active, athletes tend to have better visual abilities. Despite acknowledging this relationship in a 2011 review, a team headed by Aaron Zimmerman of The Ohio State University suggests that more rigorous testing is needed. While athletes such as joggers tend to have better contrast sensitivity, Zimmerman and his colleagues point out that some studies find no evidence for this relationship. In addition, these researchers note that there is no reason to believe that physical activity causes increased contrast sensitivity, suggesting that people with high contrast sensitivity may simply be more likely to become athletes.

Dopamine

Dopamine is a neurotransmitter, or chemical messenger in your brain, that helps to regulate mood. As reported in 2008 by Simon Usborne of The Independent, jogging may help to fight addiction and make you happier by increasing the amount of dopamine that your body produces. This increase in dopamine may also lead to enhanced contrast sensitivity, as noted by Emanuel Bubl and his colleagues at the University of Freiburg, Germany. In their 2010 study, these researchers suggest that doctors may be able to detect your dopamine levels by testing your contrast sensitivity, with high contrast sensitivity indicating high dopamine levels.

Blood Flow

In a 2011 study, a team headed by Naoyuki Hayashi and colleagues at Kyushu University in Fukuoka, Japan note that jogging is associated with increased contrast sensitivity. Despite the existence of other explanations, these researchers suggest that this may arise from increased blood flow to the eyes during exercise. The results of their study reveal evidence for such a link, with blood flow to certain parts of the eye increasing during exercise. While this relationship holds for all forms of exercise, this study suggests that blood flow to the eye may have less of an effect on the contrast sensitivity of joggers due to the relatively low intensity of jogging.