The Acute Effects of a Multi-Ingredient Herbal Supplement on Performance Fatigability: A Double-Blind, Randomized, and Placebo-Controlled Trial

The purpose of the present study was to examine the acute effects of an herbal supplement containing a 70:30 blend of Rhaponticum carthamoides extract and Rhodiola rosea extract, respectively, on performance fatigability and the affective responses prior to and following exercise. Thirty men (age = 22.3 ± 4.1 years) volunteered for this randomized, placebo-controlled, double-blind, cross-over study. Following familiarization, participants visited the laboratory on three separate occasions where they consumed one 350 mg dose, a 175 mg dose of the supplement plus 175 mg of maltodextrin, or a placebo. Participants completed feeling, arousal, and mood surveys at supplement ingestion and following testing. Ninety minutes following ingestion, participants performed five sets of 30 maximal, concentric, leg extension muscle actions at 180°/sec, with one minute of rest between sets. Peak torque, average torque, and total work were calculated for each set, and the rating of perceived exertion (RPE) was assessed after each set. Data were analyzed with a repeated measures analysis of variance and intent-to-treat approach. For the performance variables, there was no interaction (p ≥ 0.317) or treatment effect (p ≥ 0.660), however, all torque variables decreased across sets and plateaued at sets 4-5, whereas RPE increased across sets (p < 0.001). For the affective responses, there was no interaction (p ≥ 0.781) or treatment effect (p ≥ 0.314); however, participants felt better, had an improved mood, and felt more aroused following testing (p < 0.047). This combination of herbal extracts likely does not acutely influence performance fatigability during high-intensity, repeated muscle actions.

Keywords: Rhodiola rosea; dietary supplements; fatigue; muscle strength; nutrition supplementation; rhaponticum carthamoides.