Dose-Response Effects of Short-Term *Rhodiola Rosea* on Anaerobic Performance and Cognitive Function in Resistance-Trained Adults: A Randomized, Double-Blind, Placebo-Controlled Crossover Trial
Dose-Response Effects of Short-Term Rhodiola Rosea on Anaerobic Performance and Cognitive Function in Resistance-Trained Adults: A Randomized, Double-Blind, Placebo-Controlled Crossover Trial
This study will evaluate whether 7 days of Rhodiola rosea (golden root) supplementation can improve resistance-exercise performance and cognitive function in resistance-trained men and women. Participants will complete four 7-day periods in a randomized, double-blind, crossover order: (1) no-capsule control, (2) placebo, (3) low-dose Rhodiola rosea, and (4) high-dose Rhodiola rosea. On day 7 of each period, they will report to the laboratory for performance testing that includes bench press and leg press 1-repetition maximum (1RM), a third set to failure at 60% 1RM, Tendo-derived mean and peak power, a 30-second Wingate test, and the paper-and-pencil Stroop Color-Word Test for executive function. Secondary outcomes include ratings of perceived exertion, readiness to perform (visual analog scale), and heart rate and blood pressure measured at rest and 1 minute after exercise. The central hypothesis is that short-term Rhodiola rosea, compared with control and placebo, will produce small but measurable improvements in strength, set-to-failure volume, and Stroop performance, with minimal changes in hemodynamics.
Rationale: Rhodiola rosea is an adaptogenic plant extract that has shown modest, context-dependent effects on perception of effort, cognition, and exercise performance. Prior studies suggest that benefits may be more evident with acute or short-term administration; however, the results are heterogeneous. This study employs a within-subject approach in resistance-trained adults to minimize between-person variability and investigate potential dose-response effects over a short time frame.
Design overview: After screening and a familiarization visit, each participant completes four 7-day periods: (1) no-capsule control, (2) placebo, (3) low-dose RR, and (4) high-dose RR. Capsule periods are randomized and double-blind; the no-capsule control precedes capsule periods to avoid carryover of expectancy. Study staff, participants, and outcome assessors are blinded during capsule periods. On day 7 of each period, participants attend a single testing visit conducted under standardized conditions (time of day, pre-test instructions). Short-latency effects are targeted by scheduling capsule ingestion approximately 60 minutes before testing during capsule periods.
Intervention: Low- and high-dose RR are provided in identical-appearing capsules. Placebo capsules contain inert filler. Product identity, dose, and lot information are recorded in the Intervention section of the record. Capsule count and participant logs monitor adherence.
Standardization and compliance: Participants are asked to maintain their habitual training and diet and to refrain from using additional ergogenic aids for a period of 7 days. They record total energy and macronutrients for the three days before each testing day. Testing sessions follow a consistent order of tasks established during the familiarization phase. Resting vital signs are obtained after a seated rest; post-exercise measures are obtained 1 minute after completion of designated tasks.
Population: Resistance-trained adults (men and women) who meet eligibility criteria and provide informed consent. Additional eligibility details are specified in the Eligibility section of the record. The female hormonal status/menstrual phases are documented when available to aid in interpretation.
Data handling and analysis (overview): The primary analyses compare conditions within participants using linear mixed-effects models, with participant as a random effect and fixed terms for condition and period. Additional prespecified covariates (e.g., sex, pre-visit dietary intake) may also be included. Order and carryover are evaluated as appropriate. Missing data are handled using model-based methods consistent with the statistical plan.
Safety: Adverse events are monitored throughout each period, with procedures for reporting to the IRB per institutional policy.
Inclusion Criteria:
Exclusion Criteria: