Non-placebo Controls To Determine The Magnitude Of Ergogenic Interventions: A Systematic Review And Meta-analysis

Abstract

Bitter solutions may not be effective in improving functional performance in older adults. Lack of significant findings could be due to 1) inappropriately low dosages of caffeine to produce an ergogenic effect 2) caffeine is not as effective quinine in stimulating oral receptors in the mouth 3) decreased chemosensitivity and oral receptor function due to age related changes. Further research is needed to assess the effects of bitter solution mouthwashes in older adults as a way to effect acutely change performance measures. PURPOSE: Cannabidiol (CBD) may exert physiological and psychological effects that benefit athletes (e.g. protect against neurological damage; reduce inflammation, anxiety and pain) (McCartney et al. 2020). This pilot study investigated the effects of CBD on physiological responses to exercise to determine its practical utility within the sporting context. METHODS: On two occasions, nine endurance-trained males (VO2max: 57.4±4.0 mL•min -1 •kg -1 ) ran for 60 mins at a fixed, moderate-intensity (70% VO2max) (RUN 1) before completing an incremental run to exhaustion (RUN 2) on an indoor treadmill (21.4±0.4°C). Participants received an oral dose of CBD (300 mg) or placebo 1.5 hrs prior to exercise in a randomised, doubleblind, crossover design. Respiratory gases were sampled continuously between 24-32, 37-45 and 50-58 mins of submaximal exercise; heart rate (HR), ratings of perceived exertion (RPEs), ratings of pleasure-displeasure, blood glucose (BG) and lactate (BL) concentrations were measured at 20-min intervals. Blood was drawn at baseline, pre-and post-RUN 1, post-RUN 2 and 1 hr post-RUN 2. RESULTS: CBD tended to increase submaximal oxygen consumption (+24±13 mL•min -1 , p=0.094). No differences in HR, RPE, BG, BL, or respiratory exchange ratio were observed during submaximal exercise (p's>0.10); VO2max (CBD: 3987±462; Placebo: 3868±577 mL•min -1 ; p=0.121) and time to exhaustion (CBD: 1286±150; Placebo: 1246±197 sec; p=0.204) were also similar during the incremental run. CBD tended to increase ratings of pleasure at 20-(p=0.050) and 40-mins (p=0.065) of submaximal exercise. Serum interleukin (IL)-6, IL-1β, tumor necrosis factor-α, lipopolysaccharide and myoglobin concentrations increased from baseline with exercise (i.e., post-RUN 1, post-RUN 2 and/or 1 hr post-RUN 2, p's<0.05); however, the change was too small to reliably evaluate the effect of CBD. Plasma CBD concentrations were 0±0, 3±2, 77±18, 164±35 and 99±26 ng.mL -1 at each respective time point. CONCLUSIONS: These preliminary findings suggest that CBD has potential to alter physiological responses during exercise. Further research involving a larger participant sample is required to confirm and better understand these effects.

Extracellular Buffering Supplements to Improve Exercise Capacity and Performance: A Comprehensive Systematic Review and Meta-analysis

“…Exercise comparisons here were made to a placebo session/group, however, real-world effects of supplements include both the active component of the supplement in addition to placebo effects [55]. Athletes might expect slightly greater effects than those shown here when ingesting these supplements due to the physiological and psychological components associated with supplementation [55].…”

“…Single dose ingestion strategies appear to lead to greater exercise improvements than split-dose ingestion strategies, while ingestion in solution was more beneficial for exercise outcomes than in gelatine capsules although certainty in these outcomes was low. Greater improvements with solution could be due, in part, to placebo effects associated with its ingestion [55], since it might be easier to identify the intervention condition due to its distinct salty taste and correct supplement identification can lead to greater ergogenic effects [56]. There was weak evidence that chronic ingestion led to greater performance improvements than acute supplementation.…”