The effectiveness and efficacy of Rhodiola rosea L.: A systematic review of randomized clinical trials 

This systematic review published in 2011 found 11 randomised control trials that used oral Rhodiola rosea extracts as a monotherapy in both healthy and diseased populations published between 2000-2009. Six of these studies reviewed the impact on physical performance in healthy adults. 

References:

Hung, S. K., Perry, R., & Ernst, E. (2011). The effectiveness and efficacy of Rhodiola rosea L.: A systematic review of randomized clinical trials. Phytomedicine, 18(4), 235–244. https://pubmed.ncbi.nlm.nih.gov/21036578/