Objectives: This study aimed to explore the effects of four days of Rhodiola Rosea (RR) supplementation on bench-press and bench-pull exercises under resting or mental fatigue conditions in young healthy individuals. Methods: Eighteen participants (seven women) visited the laboratory on five occasions separated by 7 days—one preliminary session and four experimental sessions. In the preliminary session, participants were familiarised with the Stroop and Multiple Object Tracking tests, after which their one-repetition maximum loads for bench presses and bench pulls were determined. The four experimental sessions had the same protocol, differing only in the supplement (RR or placebo) and mental task conditions (Stroop test or control video). Participants were assigned randomly and counterbalanced to each experimental condition: (I) RR and Stroop test, (II) RR and control video, (III) placebo and Stroop test, and (IV) placebo and control video. Results: The main findings indicate that RR supplementation has trivial-to-small effects in terms of mental fatigue, visuo-cognitive processing, or perceived exertion. However, RR was significantly superior to placebo on strength performance in the control video condition during some sets, as it increased the number of repetitions performed in the bench press and the fastest velocity in the bench pull. Out of 52 comparisons, 17 small effect sizes were observed, with 14 favouring RR and 3 favouring placebo, with the remaining differences being trivial. Conclusions: These results suggest that short-term RR supplementation is safe and provides its main ergogenic effects on physical performance rather than in visuo-cognitive or mental outcomes.

Purpose: This study aimed to assess the impact of Rhodiola rosea ( RR ) supplementation on the dynamics of the accommodative response and digital eye strain (DES) symptoms following 30‐min visual tasks with different levels of cognitive demand. Methods: Eighteen young adults (mean age ± SD: 24.6 ± 4.0 years) participated in this placebo‐controlled, triple‐blind, balanced crossover study. Participants completed four sessions separated by 1 week in a randomised order. The sessions differed in the supplement (RR or placebo) and cognitive demand of the visual task (Stroop test or control video). The supplementation consisted of 1200 mg of RR or placebo per day for 4 days (two 300 mg capsules every 12 h) and a washout period of 3 days was allowed before the subsequent condition. The lag and variability of the accommodative response were measured at 500, 40 and 20 cm using an open‐field autorefractor, and DES symptoms were assessed using a 10‐item questionnaire. Results: RR supplementation caused a reduction in the variability of accommodation ( p = 0.007) and the perceived levels of ‘Blurred vision when looking into the distance at the end of the near task’ ( p = 0.009). However, the lag of accommodation ( p = 0.15) and the remainder of the DES symptoms were unaffected by the ingestion of RR ( p > 0.05 in all cases). The reduction in the variability of accommodation after RR intake was observed at 40 and 20 cm ( p ‐values <0.001 and 0.04, respectively), but not at far distance (500 cm, p = 0.40). Conclusions: These findings show that RR supplementation (1200 mg/day for 4 days) produced a reduction in the variability of accommodation and one of the assessed DES symptoms, suggesting that it could be considered as a potential strategy to prevent or manage DES. However, further research is needed to determine its clinical relevance and optimise dosage and timing.

The main objective of this placebo-controlled, triple-blind, balanced crossover study was to assess the acute effects of phenylcapsaicin (PC) intake (2.5 mg) on intraocular pressure (IOP), ocular perfusion pressure (OPP), and heart rate (HR) during a 30-min cycling task performed at 15% of the individual maximal power. Twenty-two healthy young adults performed the cycling task 45 min after ingesting PC or placebo. IOP was measured with a rebound tonometer before exercise, during cycling (every 6 min), and after 5 and 10 min of recovery. OPP was assessed before and after exercise. HR was monitored throughout the cycling task. We found an acute increase of IOP levels related to PC consumption while cycling (mean difference = 1.91 ± 2.24 mmHg; p = .007, ), whereas no differences were observed for OPP levels between the PC and placebo conditions (mean difference = 1.33 ± 8.70 mmHg; p = .608). Mean HR values were higher after PC in comparison with placebo intake (mean difference = 3.11 ± 15.87 bpm, p = .019, ), whereas maximum HR did not differ between both experimental conditions (p = .199). These findings suggest that PC intake before exercise should be avoided when reducing IOP levels is desired (e.g., glaucoma patients or those at risk). Future studies should determine the effects of different ergogenic aids on IOP and OPP levels with other exercise configurations and in the long term.