Investigating the immediate and cumulative effects of isometric squat exercise for different weight loads on intraocular pressure: a pilot study

Abstract

Background: The execution of resistance exercise against heavy loads promotes an acute intraocular pressure (IOP) rise, which has detrimental effects on ocular health. However, the effect of load on the IOP behavior during exercise remains unknown due to technical limitations. Hypotheses: IOP monitoring during isometric squat exercise permits assessment of IOP behavior during physical effort. Second, greater loads will induce a higher IOP rise. Study Design: Randomized cross-sectional study. Level of Evidence: Level 2. Methods: Twenty-six young adults (13 women, 13 men) performed an isometric squat exercise against 3 loads relative to their maximum capacity (low, medium, and high). IOP was measured before, during (1 measurement every 6 seconds), and after exercise (10 seconds of recovery). Results: There was a progressive IOP rise during exercise, which was dependent on the load applied (Bayes factor10 >100). Higher IOP values were found in the high load condition in comparison with the medium (mean IOP difference = 1.5 mm Hg) and low (mean IOP difference = 3.1 mm Hg) conditions, as well as when the medium load was compared with the low load condition (mean IOP difference = 1.6 mm Hg). Men reached higher IOP values in comparison with women during the last measurements in the high load condition. Ten seconds of recovery were enough to obtain IOP values similar to baseline levels. Conclusion: Isometric squat exercise induces an immediate and cumulative IOP elevation, which is positively associated with the load applied. These IOP increments return to baseline values after 10 seconds of recovery, and men demonstrate a more accentuated IOP rise in comparison with women when high levels of effort are accumulated. Clinical Relevance: These findings may help in better management of different ocular conditions and highlight the importance of an individualized exercise prescription in clinical populations.