Synergistic Effect of Rhodiola rosea and Caffeine Supplementation on the Improvement of Muscle Strength and Muscular Endurance: A Pilot Study for Rats, Resistance Exercise-Untrained and -Trained Volunteers

Abstract

Multi-level studies have shown that Rhodiola rosea (RHO) and Caffeine (CAF) have the potential to be nutritional supplements to enhance physical performance in resistance exercise-untrained and -trained subjects. This study examined the synergistic effects of RHO (262.7 mg/kg for rats and 2.4 g for volunteers) and CAF (19.7 mg/kg for rats and 3 mg/kg for volunteers) supplementation on improving physical performance in rats, resistance exercise-untrained volunteers and resistance exercise-trained volunteers. Rats and volunteers were randomly grouped into placebo, CAF, RHO and CAF+RHO and administered accordingly with the nutrients during the training procedure, and pre- and post-measures were collected. We found that RHO+CAF was effective in improving forelimb grip strength (13.75%), erythropoietin (23.85%), dopamine (12.65%) and oxygen consumption rate (9.29%) in the rat model. Furthermore, the current results also indicated that the combination of RHO+CAF significantly increased the bench press one-repetition maximum (1RM) (16.59%), deep squat 1RM (15.75%), maximum voluntary isometric contraction (MVIC) (14.72%) and maximum repetitions of 60% 1RM bench press (22.15%) in resistance exercise-untrained volunteers. Additionally, despite the excellent base level of the resistance exercise-trained volunteers, their deep squat 1RM and MVIC increased substantially through the synergistic effect of RHO and CAF. In conclusion, combined supplementation of RHO+CAF is more beneficial in improving the resistance exercise performance for both resistance exercise-untrained and -trained volunteers. The present results provide practical evidence that the synergies of RHO and CAF could serve as potential supplementary for individuals, especially resistance exercise-trained subjects, to ameliorate their physical performances effectively and safely.

Rhodiola rosea as an adaptogen to enhance exercise performance: a review of the literature

“…The origin of this higher dose appears to be a study conducted by Walker et al (26) , who sought to employ a dose higher than manufacturer recommendations in an attempt to approach doses shown to exert beneficial effects on mitochondrial ATP content in rodents (13) . While one other investigation used a higher total dose of RR (2400 mg/d), the lower concentration of bioactive compounds (0•5 % salidroside, rosavin not reported) (39) led to a lower absolute dose of these compounds compared with the aforementioned studies. The trial of Walker et al (26) first administered a daily dose of 1500 mg/ d (3 % rosavin, salidroside not reported), although this was in the context of a muscular endurance test (incremental forearm wrist flexion to exhaustion).…”

“…Literature search. Over the past two decades, more than a dozen clinical trials have examined the effects of RR on exercise performance and adaptations (Table 1) (23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39) . To ensure this narrative review accurately represents the current body of scientific evidence, searches were performed using several electronic databases (PubMed®, Web of Science TM and Scopus), with screening of relevant articles to identify research reporting the effects of RR on exercise performance and related outcomes in humans.…”

“…Eight of the clinical studies identified included bicycle ergometry as an exercise testing modality, and the specific protocols varied widely (23,24,25,28,29,30,35,36) . Three trials included running, either on a treadmill (33,37) or as a marathon race (31,32) , one trial employed walking on a treadmill in a climate chamber (34) , one trial used rowing ergometry (27) and three trials incorporated resistance exercise, including wrist flexion (26) , bench press (38,39) and/or squat exercises (39) .…”

“…Two recent trials have examined whether RR supplementation improves resistance exercise performance, with one employing acute supplementation prior to exercise testing (38) and the other pairing chronic supplementation with supervised resistance training (39) . In untrained participants, Liu et al (39) found that 30 d of supplementation with 2400 mg/d RR (0•5 % salidroside, rosavin not reported) alongside supervised resistance training produced superior performance adaptations compared with placebo. The resistance training programme contained thirteen training sessions over the 30-d study and included the bench press and deep squat exercises, with 4 sets of 10 repetitions at 60 % of the pre-training 1-repetition maximum (1RM) for the first 15 d and 4 sets of 8 repetitions at 70 % of the pre-training 1RM for the last 15 d. In the RR group, greater increases were observed for bench press 1RM (9 % greater increase with RR compared with placebo; P = 0•01), squat 1RM (7•5 % greater increase with RR compared with placebo; P = 0•01), knee extension maximal voluntary isometric contraction (8•6 % greater increase with RR compared with placebo; P = 0•008) and bench press repetitions to failure (12•7 % greater increase with RR than placebo; P = 0•005).…”

“…Nonetheless, training statuses were designated by study authors as untrained ( n 2), recreationally active ( n 4), active ( n 4) and trained/athletes ( n 5), with training status not reported in one investigation. Collectively, based on a recent Participation Classification Framework (40) , most participants likely fell within the tier 1 (recreationally active) or tier 2 (trained/developmental) categories, with the possibility of some untrained participants falling within tier 0 (sedentary) (24,39) and some highly trained participants belonging to tier 3 (highly trained/national level) (27) . Six studies used acute RR supplementation protocols (26,29,30,33,36,38) , defined here as 1–7 d of supplementation, nine implemented chronic supplementation (>7 d; range 8–38 d) (23,24,27,28,31,32,34,37,39) and one incorporated both acute and chronic supplementation strategies (25) .…”