Caffeine, lactic acid, or nothing: What effect does expectation have on men's performance and perceived exertion...

We tested the impact of subjects' belief in an ingested substance's ergogenic or ergolytic properties on muscular endurance performance and perceived exertion.

Trained men (n = 15, age = 41 ± 4 y; body mass = 82.1 ± 15.8 kg; height = 173 ± 8 cm; experience = 7.4 ± 2.3 y) completed one set to failure at 80% repetition maximum of the bench press under three conditions. In all conditions, subjects ingested capsules of an identical, inert substance (300 mg cellulose), but, in a randomized order, subjects were told that they were either ingesting caffeine (Placebo), lactic acid (Nocebo), or cellulose (Control) and received information on the respective alleged ergogenic/ergolytic/neutral effects of each. Repetitions completed and rating of perceived exertion (RPE) were recorded. The data were analyzed among conditions using a Friedman test with post hoc analyses accomplished through Durbin-Conover tests. Spearman correlations were used to compare repetitions performed and RPE between Nocebo and Placebo conditions. Statistical significance was set at P ≤ 0.05.

Subjects lifted more (P < 0.001) repetitions in the Placebo condition (14.1 ± 3.0) versus Control (10.3 ± 2.9) or Nocebo (7.5 ± 2.6), while Control and Nocebo performances were similar (P = 0.192). Lower RPE was noted in Placebo versus Control (P = 0.003) and Nocebo (P < 0.001) and lower in Control versus Nocebo (P = 0.025). Subjects who performed more repetitions with Placebo tended to perform fewer repetitions under the Nocebo condition (Spearman's Rho =-0.578).

This study believes that the ergogenic or ergolytic properties of a substance can measurably impact upper-body muscular endurance performance and RPE in trained men.