Exercise intensity determines the magnitude of IOP decrease after running.

The effects of the intensity, duration and quantity (intensity x duration) of exercise on the reduction of intraocular pressure (IOP) in healthy and physically fit individuals were studied. Five minutes after 15 minutes of exercise at 70%, 55% and 40% of maximum exercise load (%HRmax) the IOP decreased 4.3 +/- 0.7 mmHg, 2.2 +/- 0.7 mmHg and 0.6 +/- 0.5 mmHg, respectively. The magnitude of IOP reduction increased with exercise load. Running for 7.5 minutes at 70%HRmax decreased IOP comparable to 15 minutes of running at the same exercise load (4.4 +/- 0.6 mmHg). Twenty-five minutes of running at 40%HRmax is almost the same quantity of exercise as 15 minutes of running at 70%HRmax. However, the former did not result in IOP reductions to equal the latter (2.3 +/- 0.5 vs 4.4 +/- 0.6 mmHg). The amount of IOP reduction after short-term exercise seems to depend on the intensity of exercise, not on the duration of exercise or the quantity of exercise.