Clinical trial design for Bergenia samples, double blind placebo controlled crossover study

The study was planned to study whether acute or a 7-day Bergenia intake has any effects on endurance exercise capacity or muscle strength. The study included two experimental designs: to investigate the acute effects and the effect of 7-day use of Bergenia. The study was double blind placebo controlled crossover study. Thirty physically active men were divided into three groups who ingested one, two or four capsules containing either isomalt (placebo) or Bergenia extract (100 mg) plus isomalt. The order of the placebo and Bergenia tests was randomized so that half of each group had first placebo and then Bergenia tests and the other half had the opposite order. The endurance test was maximal incremental cycling test in which maximal power, maximal blood lactate, maximal heart rate, maximal ventilation, VO2max as well as RPE and glucose concentration at exhaustion were determined. The strength tests were maximal isometric leg press and vertical counter-movement jump. The results of the present study showed that the Bergenia supplementation with the current doses of 100–400 mg does not have almost any acute or a 7-day usage effect on endurance and maximal force characteristics in physically active men. Bergenia supplementation did not cause any negative effects on the present subjects either. In the previous studies it was shown that supplementation of animals with the extract from fermented leaves of Bergenia enhanced the maximum swimming capacity of mice. We may make a hypothesis that probably other dose ranges and prolongation of supplementation time would be more correct for future human experiments.