R.M. Houser, C.K. Tang, S.O. Henry, R. Bulson

Pacific University, Forest Grove, OR

Glaucoma is the second leading cause of irreversible blindness, afflicting millions of people worldwide. Previous research suggests physical exercise may have promising, beneficial effects on intraocular pressure (IOP), one of the major risk factors for glaucoma. However, there is a notable lack of research on the differential effects of various exercise intensities on IOP. PURPOSE: To determine the acute effects of exercise intensity on IOP. METHODS: Fourteen volunteer participants (6 male, 8 female; 20.1 ± 1.10 years of age; 70.31 ± 13.50 kg mass; 171.45 ± 8.50 cm stature) with normal IOP (17.03 ± 3.15 mmHg) completed the study. Each participant completed a standardized step test to estimate VO2 max, which was used to prescribe individualized treadmill speeds representing three exercise intensities (45%, 65%, and 95% VO2 max). In a random and repeated design, participants completed 2.0 km at each intensity. This experimental design isolated power (exercise intensity) as the variable of interest, while holding total work constant for each condition (2.0 km). Baseline IOP, heart rate, and blood pressure were measured prior to each exercise intensity and again at time 0, 5, 10, and 20 minutes post-exercise. Time 0 IOP data was used for analysis. Repeated measures one-way ANOVA with post hoc tests compared IOP (time 0) for the four levels of exercise intensity (rest/baseline, low, moderate, high). RESULTS: High intensity exercise reduced IOP (12.94 ± 2.20 mmHg) as compared to baseline (p=0.001), moderate intensity (IOP = 14.96 ± 2.04 mmHg, p<0.001), and low intensity (IOP = 15.91 ± 2.94 mmHg, p=0.004). Neither moderate intensity nor low intensity exercise lowered IOP as compared to baseline. CONCLUSION: High intensity exercise was the only condition associated with an acute reduction of IOP. Therefore, high intensity exercise regimens may be necessary to elicit meaningful, albeit transient, reductions in IOP. As this study only investigated the acute effects of exercise intensity, it would be beneficial to examine the chronic effects of exercise on IOP.

The project was supported by the Pacific University College of Arts and Science Research Grant.

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