Effects of benzodiazepine during a Wingate test: interaction with caffeine.

To assess the effects of benzodiazepine alone and associated with caffeine on performance and substrate responses during supramaximal exercise, seven healthy volunteers performed the Wingate test after ingestion of placebo (Pla), benzodiazepine alone, i.e., 1 mg of lorazepam (Bz), and benzodiazepine followed by 250 mg of caffeine (Bz-Caf). Peak power (PP), mean power (MP), and percentage of power decrease (%PD) were determined, and substrate responses were estimated by blood lactate and catecholamine concentrations. Four hours after Bz ingestion, there was a significant decrease in PP (PPBz: 626 +/- 72 vs PPPla: 669 +/- 78 W), maximal blood lactate (La max) (La maxBz: 9.5 +/- 1.5 vs La maxPla: 12.4 +/- 1.8 mmol.l-1), and end-exercise epinephrine (E) (EBz: 339 +/- 113 vs EPla: 672 +/- 247 ng.l-1). No other changes were noted. Caffeine ingestion 1 h before the test (Bz-Caf) corrected the decrease in La max (La maxBz-Caf: 11.5 +/- 1.4 mmol.l-1) and E (EBz-Caf: 573 +/- 190 ng.l-1) but was unable to prevent the impairment of performance (PPBz-Caf: 625 +/- 68 W vs PPPla). Moderate benzodiazepine intake significantly altered performance and substrate responses during supramaximal exercise. Moderate caffeine intake antagonized the metabolic but not the performance effects of 1 mg of lorazepam.