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FITNESS A fi tter outlook – exercise improves eyesight A


ccording to a review of the current research, exercise is associated with an improvement in two meas-


ures of visual prowess: contrast sensitivity and visual acuity. Contrast sensitivity is the ability to dis-


tinguish between overlapping, stationary and poorly outlined objects. For example, those with low contrast sensitivity may not detect black letters on a poorly-lit white page, while those with high contrast sen- sitivity may be able to distinguish between two overlapping, near-identical objects from a distance in poor light. Visual acuity, meanwhile, is the ability to see fi ne detail. Athletes display higher levels of con-


trast sensitivity, and while exercise may or may not directly improve this measure of vision, previous research has suggested that the chemical dopamine may play a


Vision may be better even after exercise


part. Dopamine levels increase with exer- cise, and higher levels of this chemical have been shown to increase contrast sensitivity. In addition, the review showed that those who exercised had better visual acuity than


non-exercisers. Indeed, visual acuity was shown to improve during exercise – as the inten- sity of the participants’ cycling increased, so visual acuity improved. Researchers repeated the tests two days later and found that visual acuity remained higher than before exercise, indicating that you may be able to retain these gains in the longer term, not just during exercise. These improvements in visual acuity are thought to result from the temporary boost to various systems and functions in the body that occur as a response to phys- ical exertion: the body interprets exercise as a form of stress and instigates the prim- itive ‘fi ght or fl ight’ response. As part of this process, pupil size increases, allow- ing more light into the eye and enhancing visual acuity.


Zimmerman, AB, Lust and KL, Bullimore, MA (2011). Visual Acuity and Contrast Sensitivity Testing for Sports Vision. Eye & Contact Lens. 37(3): 153-159 Exercise lowers prostate cancer deaths I


n a study by Harvard Medical School and the University of California, US, researchers tracked 51,529 male health professionals over an 18-year period. Among the 2,705 who were diag- nosed with prostate cancer, the amount and intensity of exercise undertaken was correlated with risk of death. Any form of activity conveyed a pro-


tective effect, but the most signifi cant reductions in risk were associated with vigorous exercise. Compared to those who did the least amount of activity,


those doing 10 or more hours of non-vig- orous activity a week had a 49 per cent reduction in risk of death from all causes. Those doing more than three hours of


vigorous activity a week had a 61 per cent reduction in risk of mortality from prostate cancer – even though they had already been diagnosed with this condition. Researchers proposed a number of mechanisms by which exercise conveys its protective effects. Previously it’s been demonstrated that higher levels of insulin production and infl ammation are associated


with increased risk of prostate cancer death. Exercise has been shown to raise the body’s sensitivity to insulin, resulting in lower insulin production and levels of infl ammation. Physical activity has also been shown to boost activity of the innate immune system – the body’s fi rst line of defence against infection or disease. While the present study was unable to identify which of these mechanisms was responsible, it was considered likely that one or more contributes to the pro- tective effects of exercise.


Kenfi eld, SA et al (2011). Physical activity and survival after prostate cancer diagnosis in the health professionals follow-up study. Journal of Clinical Oncology. 29(6): 726-732


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