Caffeine (CAF) is widely consumed across sport and exercise for its reputed ergogenic properties, including central nervous stimulation and enhanced muscular force development. However, expectancy and the related psychological permutations that are associated with oral CAF ingestion are generally not considered in most experimental designs and these could be important in understanding if/how CAF elicits an ergogenic effect. The present paper reviews 17 intervention studies across sport, exercise, and cognitive performance. All explore CAF expectancies, in conjunction with/without CAF pharmacology. Thirteen out of 17 studies indicated expectancy effects of varying magnitudes across a range of exercise tasks and cognitive skills inclusive off but not limited to; endurance capacity, weightlifting performance, simple reaction time and memory. Factors, such as motivation, belief, and habitual CAF consumption habits influenced the response. In many instances, these effects were comparable to CAF pharmacology. Given these findings and the lack of consistency in the experimental design, future research acknowledging factors, such as habitual CAF consumption habits, habituated expectations, and the importance of subjective post-hoc analysis will help to advance knowledge within this area.

Polyphenols are secondary metabolites involved in a myriad of critical processes in plants. Over recent decades, special attention has been paid to the anti-oxidative role of fruit-derived polyphenols in the human diet, with evidence supporting the contribution of polyphenols in the prevention of numerous non-communicable disease outcomes. However, due to the low concentration in biological fluids in vivo, the antioxidant properties of polyphenols seem to be related to an enhanced endogenous antioxidant capacity induced via signaling through the nuclear respiratory factor 2 pathway. Polyphenols also seem to possess anti-inflammatory and antioxidant properties and have been shown to enhance vascular function via nitric oxide mediated mechanisms. Consequently, there is rationale to support fruit-derived polyphenol supplementation to enhance exercise performance, possibly via improved muscle perfusion. Fruit-derived polyphenol supplementation in exercise studies have included a variety of fruits, e.g., New Zealand blackcurrant, pomegranate, and cherry, in the form of extracts (multicomponent or purified), juices and infusions to varying degrees of benefit. For example, research has yet to link the health-related benefits of black elderberry (Sambucus nigra L.) ingestion to exercise performance in spite of the purported health benefits associated with black elderberry provision in vitro and in vivo models, which has been attributed to their high antioxidant capacity and polyphenol content. This review summarizes the existing evidence supporting a beneficial effect of fruit-derived polyphenols on various biological processes and outlines the potential for black elderberry ingestion to improve nitric oxide production, exercise performance, and the associated physiological responses before-, during- and post-exercise.

Caffeine (CAF) has been reported to improve various facets associated with successful soccer play, including gross motor skill performance, endurance capacity and cognition. These benefits are primarily attributed to pharmacological mechanisms. However, evidence assessing CAF’s overall effects on soccer performance are sparse with no studies accounting for CAF’s potential psychological impact. Therefore, the aim of this study was to assess CAF’s psychological vs. pharmacological influence on various facets of simulated soccer performance. Utilising a double-dissociation design, eight male recreational soccer players (age: 22 ± 5 years, body mass: 78 ± 16 kg, height: 178 ± 6 cm) consumed CAF (3 mg/kg/body mass) or placebo (PLA) capsules, 60 min prior to performing the Loughborough Intermittent Shuttle Test (LIST) interspersed with a collection of ratings of perceived exertion (RPE), blood glucose and lactate, heart rate and performing the Loughborough Soccer Passing Test (LSPT). Whole-body dynamic reaction time (DRT) was assessed pre- and post- LIST, and endurance capacity (T_LIM) post, time-matched LIST. Statistical analysis was performed using IBM SPSS (v24) whilst subjective perceptions were explored using template analysis. Mean T_LIM was greatest (p < 0.001) for synergism (given CAF/told CAF) (672 ± 132 s) vs. placebo (given PLA/told PLA) (533 ± 79 s). However, when isolated, T_LIM was greater (p = 0.012) for CAF psychology (given PLA/told CAF) (623 ± 117 s) vs. pharmacology (given CAF/told PLA) (578 ± 99 s), potentially, via reduced RPE. Although DRT performance was greater (p = 0.024) post-ingestion (+5 hits) and post-exercise (+7 hits) for pharmacology vs. placebo, psychology and synergism appeared to improve LSPT performance vs. pharmacology. Interestingly, positive perceptions during psychology inhibited LSPT and DRT performance via potential CAF over-reliance, with the opposite occurring following negative perceptions. The benefits associated with CAF expectancies may better suit tasks that entail lesser cognitive-/skill-specific attributes but greater gross motor function and this is likely due to reduced RPE. In isolation, these effects appear greater vs. CAF pharmacology. However, an additive benefit may be observed after combining expectancy with CAF pharmacology (i.e., synergism).

The aim of this study was to assess the effects of post-exercise sodium bicarbonate (NaHCO₃) ingestion (0.3 g.kg⁻¹ body mass) on the recovery of acid-base balance (pH, ${\text{HCO}}_3^{-}$, and the SID) and subsequent exercise performance in elite boxers. Seven elite male professional boxers performed an initial bout of exhaustive exercise comprising of a boxing specific high-intensity interval running (HIIR) protocol, followed by a high-intensity run to volitional exhaustion (T_LIM1). A 75 min passive recovery then ensued, whereby after 10 min recovery, participants ingested either 0.3 g.kg⁻¹ body mass NaHCO₃, or 0.1 g.kg⁻¹ body mass sodium chloride (PLA). Solutions were taste matched and administered double-blind. Participants then completed a boxing specific punch combination protocol, followed by a second high-intensity run to volitional exhaustion (T_LIM2). Both initial bouts of T_LIM1 were well matched between PLA and NaHCO₃ (ICC; r = 0.94, p = 0.002). The change in performance from T_LIM1 to T_LIM2 was greater following NaHCO₃ compared to PLA (+164 ± 90 vs. +73 ± 78 sec; p = 0.02, CI = 45.1, 428.8, g = 1.0). Following ingestion of NaHCO₃, pH was greater prior to T_LIM2 by 0.11 ± 0.02 units (1.4%) (p < 0.001, CI = 0.09, 0.13, g = 3.4), whilst ${\text{HCO}}_3^{-}$ was greater by 8.8 ± 1.5 mmol.l⁻¹ (26.3%) compared to PLA (p < 0.001, CI = 7.3, 10.2, g = 5.1). The current study suggests that these significant increases in acid base balance during post-exercise recovery facilitated the improvement in the subsequent bout of exercise. Future research should continue to explore the role of NaHCO₃ supplementation as a recovery aid in boxing and other combat sports.

The present work aimed to evaluate the effect of 3 mg·kg⁻¹ caffeine consumption on the standing and dynamic balance performance of older adults and sought to establish if caffeine ingestion can modulate the influence of a cognitive dual task on balance performance. Twelve apparently healthy participants (8 females) aged >65 years (72 ± 3.7 years) completed the study. Bipedal postural sway, four square step test, timed up and go, Y-balance (anterior reach only) and force-time characteristics of sit-to-stand performance were used to assess standing and dynamic balance. Attention and working memory were assessed using a serial 3s and 7s subtraction task during seated rest and completion of the bipedal standing assessment and Y-balance test. This battery of assessments was completed on two separate occasions, once following the consumption of a non-ergogenic placebo and again following the consumption of 3 mg·kg⁻¹ caffeine. The administration of treatments was randomised, counterbalanced and double-blind. Caffeine reduced performance in the bipedal standing balance assessments, evidenced by an increase in COP_ML, COP_Path, COP_Velocity. Performance during the dynamic balance tests was unaffected, other than rate of force development during the sit-to-stand, which was improved following caffeine ingestion. The introduction of a cognitive dual task had either limited effects, or improved facets of bipedal standing balance, whilst performance during the dynamic balance task was significantly reduced. In both balance assessments, there was evidence for a reduction in the performance of the cognitive task when both the balance and cognitive tests were performed simultaneously, with this effect not modulated by caffeine consumption. These findings refute the idea that caffeine ingestion may have positive effects on balance performance. However, despite a caffeine-induced reduction in bipedal standing balance, it is unlikely that caffeine ingestion would exacerbate fall risk given the limited effects in the dynamic balance tests. Future work should establish if these effects are generalisable to older frail participants and if caffeine can modulate the detrimental effects of an acute exercise bout on balance performance.