This study aimed to determine the impact of caffeine (200 mg), beta-alanine (3 g), and their combination on intraocular pressure (IOP), ocular perfusion pressure (OPP), and mean arterial pressure (MAP) at rest and after resistance training. Twenty young men (age = 23.4 ± 4.5 years) took part in this placebo-controlled, triple-blind, balanced crossover study. Participants visited the lab on four different days, with the only difference of the supplement used (caffeine, beta-alanine, caffeine + beta-alanine, and placebo). IOP and blood pressure were measured at baseline after 30 min from supplement intake, and after completing the resistance training session consisting of four alternating sets of bench press and bench pull exercises using a 20 repetition maximum load without reaching failure. In resting conditions, caffeine and the combination of caffeine + beta-alanine caused an acute IOP rise (p = .009 and .004, respectively), whereas beta-alanine and placebo intake did not affect IOP levels (p = .802 in both cases). OPP levels were not influenced by the ingestion of any supplement (p = .801), whereas MAP exhibited a significant increase after 30 min of ingesting 200 mg of caffeine (p = .012). After resistance training, there was an acute reduction of IOP, OPP, and MAP levels (p < .002 in all cases), but these effects were independent of the supplement consumed (p > .272). These findings show that beta-alanine (3 g) did not alter IOP, OPP, and MAP levels in resting conditions and after resistance training. Therefore, beta-alanine supplementation is a safe alternative when avoiding fluctuations of the ocular and cardiovascular hemodynamics is desirable (i.e., glaucoma patients or hypertensive individuals).
Keywords: dietary supplements; ergogenic aids; eye health; glaucoma prevention.