Published in the journal Nutrients, the study found “trivial-to-small effects” of the rhodiola supplement on mental fatigue, visuo-cognitive processing or perceived exertion compared to placebo.
The results suggest the RhodioZen ingredient from France-based Pharmanager Ingredients may have an ergogenic effect “mainly on physical rather than cognitive domains,” according to researchers at the Faculty of Sport Sciences, University of Granada, Spain, and other institutions in Spain and China.
Ergogenics for performance
Previous research indicates that plant-based supplements such as ginseng, ashwagandha and Brussels chicory may reduce mental fatigue, increase endurance and improve muscle function and recovery.
Herbal supplements used as ergogenic aids often have adaptogenic properties, helping the body to adapt to physical and mental stress, which is beneficial in sports and exercise settings.
Evidence suggests that rhodiola may reduce oxidative stress and muscle damage during exercise, improving athletic explosive power.
The current study noted that rhodiola upregulates catecholamines, key hormones in the stress response, potentially enhancing alertness and alleviating mental fatigue. Catecholamines heighten calcium sensitivity in muscle fibers, boosting neuromuscular transmission and potentially performance.
Study details
The study was a randomized, placebo-controlled, triple-blinded (participants, researchers and data analysts), crossover experimental trial.
Researchers recruited 18 resistance-trained participants (11 men and seven women) between the ages of 18 and 40. At the preliminary session, they administered the Stroop and Multiple Object Tracking (MOT) tests and assessed their one-rep max (1RM) loads for the bench press and bench pull exercises. Participants then attended four further experimental sessions seven days apart.
Participants consumed 600 mg of rhodiola (RhodioZen, Pharmanager Ingredients) or placebo daily, in two doses 12 hours apart for three days before each experimental session. On the experimental day, they consumed four extra pills totaling 1,200 mg one hour before arriving at the laboratory.
They were randomized to a mental task, which was either a 30-minute Stroop color word task to assess mental fatigue, the MOT test, which tracks balls on a video screen, or a placebo video.
“The assessment order in each experimental session was as follows: (I) mental task condition (Stroop test or control video), (II) MOT pre-training, (III) strength training and (IV) MOT post-training,” the researchers wrote.
A three-day washout period followed each assessment before supplement intake resumed.
“The main findings indicate that [rhodiola] supplementation did not differ from placebo in terms of mental fatigue, visuo-cognitive processing or RPE [ratings of perceived exertion],” the researchers wrote.
“However, [rhodiola] improved performance in the initial sets after watching a control video, specifically for Nrep in the bench-press and MVfastest in the bench-pull exercises.”
They noted that the findings suggest that rhodiola “may be more effective under basal conditions, in a non-stressed state, and could be classified as an adaptogen rather than a traditional nootropic.”
The study called for future research with larger sample sizes.
Source: Nutrients 2025, 17(6), 940. doi: 10.3390/nu17060940. “The Impact of Rhodiola Rosea Extract on Strength Performance in Alternative Bench-Press and Bench-Pull Exercises Under Resting and Mental Fatigue Conditions: A Randomized, Triple-Blinded, Placebo-Controlled, Crossover Trial”. Authors: D. Marcos-Frutos et al.
