The accute effects of resistance exercise on intraocular pressure

Abstract

Several studies have shown the effects of IOP reduction after practicing aerobic and anaerobic physical activities (1)(2)(3)(4) . The causes of such changes have been the target of many studies. An increase in lactic acid and in plasmatic osmolarity, and also a decrease in blood pH are considered the main causes of these IOP variations (5)(6) . Hyperventilation was also pointed out as a cause of IOP decrease after exercising (7) . An increase in IOP after the Valsalva maneuver was demonstrated when this maneuver was employed aiming to simulate weight lifting, but not weight lifting itself (8) . Marcus et al. have shown the effect of IOP reduction after isometric muscular contractions, as well as an inverse correlation with lactic acid and pH serum levels (9) . An IOP decrease was also found after physical exercises by employing isometric muscular contractions (in which the size of muscular fiber remains constant, while the tonus and the resistance against which the muscle works increase) and isokinetic muscular contractions (in which the size of the muscular fiber varies during the exercise, while the speed at which the exercise is made remains constant)(1) . Despite the above mentioned studies, there are no reports in the literature -as far as this author knows -on the variations of IOP after weight lifting itself (isotonic muscular work, in which the size of muscular fiber decreases during contraction and the speed of the exercise does not remain constant). P U R P O S ETo study IOP variations after isotonic exercise of weight lifting in the supine position, in hypertrophy work, by healthy male young individuals. Keywords: Intraocular pressure/etiology; Weight lifting; SportsThe accute effects of resistance exercise on intraocular p r e s s u r e Purpose: To study intraocular pressure (IOP) variations in healthy volunteers after weight lifting, in the supine position. Methods: A descriptive study was designed. Thirty-four individuals were preselected for this study, and a group of 25 volunteers fulfilled the inclusion criteria for joining the initial phase of this research. All of them were healthy without glaucoma. They were asked to lift an 85% top load in the supine position for 8 times. IOP was measured before and after the exercise. Student's t test was used to analyze the IOP variations. Results: A small, but significant IOP decrease (1.61 mmHg) was obtained after exposing 25 individuals (49 eyes) to a specific physical effort. Conclusions: After a session of weight lifting in the supine position with 85% top load for 8 repetitions, there is a small, but significant IOP decrease.

A comparison of the intraocular pressure response between two different intensities and volumes of resistance training

“…As in previous studies there was a significant reduction in IOP during RT sessions, regardless of the volume or intensity of exercise sessions (3,4,10) . However, previous studies assessed IOP only before and after one or two resistance exercises.…”

“…A significance level of p d" 5% was adopted, and the GraphPad Prism™ software was used. To estimate sample size, IOP values obtained in similar studies were assessed (3,4,5,10,14) . Whereas in these studies IOP reduction during exercise sessions ranged from 2.5 to 4 mmHg, we estimated that a sample of 15 subjects would have an 80% statistical power to detect a 4 mmHg reduction in IOP (standard deviation of 4 mmHg) with a two-tailed alpha < 0.05.…”

“…In this context, the reduction in blood pH causes fluidelectrolyte imbalance with consequent reduction of AH production. Lowering the pH decreases the activity of the sodium (Na + ) pump in the ciliary body to maintain local homeostasis (3) . Increased blood lactate with decreased blood pH is thus one of the main factors explaining changes in IOP caused by exercise (22) .…”

“…In isokinetic exercise, where resistance depends on the strength and speed of movement, IOP reduction is more significant than in isometric exercise (9) . Specifically with regard to RT, IOP reduction has been observed after the bench press exercise (1 set of 8 repetitions with 85% of one-repetition maximum, or 1RM) (3) . IOP reduction was also assessed immediately after the bench press and leg press exercises (3 sets of 10 repetitions with 70% 1RM) (4) .…”

Variação da pressão intraocular após teste submáximo de força no treinamento resistido

“…Esta diminuição da PIO está de acordo com estudo precedente (18) que investigou 25 indivíduos do sexo masculino (faixa etária entre 18 e 30 anos), porém que realizaram somente, um único exercício (supino) com oito repetições a 85% da carga máxima.…”