Imagery, a classic technique in psychological training, is gaining momentum in competitive sports. Despite the increasing use of imagery, its effectiveness remains debated. Robust, data-driven conclusions are still lacking. This study seeks to investigate the effects of imagery practice on enhancing athletic performance and determine the ideal dosage of such practice through a systematic review and multilevel meta-analysis. A comprehensive search across seven databases, including SportDiscus, PubMed, PsycINFO, Web of Science, MEDLINE, MEDLINE Complete, and CINAHL, yielded 23,027 studies. These were initially reviewed for title and abstract using ASReview, followed by full-text screening with Covidence. A total of 86 studies with 3593 athletes (2104 males and 1110 females) were included in this meta-analysis. Our findings indicate that imagery practice enhances athletic performance, encompassing agility, muscle strength, tennis and soccer performance, and is applicable to both tennis and soccer athletes. The efficacy of integrating imagery practice with one or two additional psychological skills trainings (PSTs) surpasses that of imagery practice in isolation. Moderation analysis revealed that engaging in imagery practice for approximately ten minutes, three times weekly over a span of one hundred days, produces the strongest performance gains. This review offers recommendations for athletes regarding the implementation of imagery practice in routine training or prior to competitions, thereby providing empirical evidence to optimize psychological training programs in competitive settings.

Plant-based protein supplements are increasingly popular, yet their efficacy in enhancing athletic performance compared to animal protein, insect protein, or other protein types remains under investigation. This study aimed to assess the effectiveness of plant-based protein on athletic abilities such as muscle strength, endurance performance, and muscle protein synthesis (MPS) rate and compare it to no- or low-protein ingestion and non-plant protein sources. Randomized controlled trials (RCTs) evaluating the beneficial and harmful effects of plant-based protein ingestion on athletic ability in healthy individuals were considered. A systematic search of six databases yielded 2152 studies, which were screened using the Covidence systematic review tool. Thirty-one studies were included for meta-analysis after independent selection, data extraction, and risk of bias assessment by two reviewers. The meta-analysis employed a Bayesian approach using the Markov chain Monte Carlo (MCMC) method through a random-effects model. The results demonstrated that plant-based protein supplements provided greater benefits for athletic performance in healthy individuals compared to the no- or low-protein ingestion group [μ(SMD): 0.281, 95% CI: 0.159 to 0.412; heterogeneity τ: 0.18, 95% CI: 0.017 to 0.362]. However, when compared to other types of protein, plant-based protein ingestion was less effective in enhancing athletic ability [μ(SMD): −0.119, 95% CI: −0.209 to −0.028; heterogeneity τ: 0.076, 95% CI: 0.003 to 0.192]. A subgroup analysis indicated significant improvements in muscle strength and endurance performance in both young and older individuals consuming plant-based protein compared to those with no- or low-protein ingestion. Nonetheless, other protein types showed greater benefits in muscle strength compared to plant-based protein [μ(SMD): −0.133, 95% CI: −0.235 to −0.034; heterogeneity τ: 0.086, 95% CI: 0.004 to 0.214]. In conclusion, while plant-based protein ingestion demonstrates superior efficacy compared to low- or no-protein ingestion, it is not as effective as other protein types such as whey, beef, or milk protein in enhancing athletic performance in healthy individuals. Registration: Registered at the International Prospective Register of Systematic Reviews (PROSPERO) (identification code CRD42024555804).

Protein supplements are a popular category of dietary supplements among fitness enthusiasts and athletes. However, research providing definitive conclusions on the effects of protein on athletic performance and post-exercise recovery remains limited. Key factors, such as protein source, timing, and optimal dosage, require further investigation to clarify their impact. A systematic search across seven databases identified 6,129 studies, which were screened using the Covidence online tool. After independent selection, data extraction, and risk of bias assessment by two reviewers, 75 studies involving 1,206 athletes were included in the meta-analysis. A multilevel meta-analysis synthesized data from the included studies using a Bayesian hierarchical model with the brms package. Publication bias was assessed using a funnel plot generated with the PublicationBias package and by calculating the P value of Egger's test through the metafor package. Additionally, a moderation analysis with the brms package was conducted to examine the relationship between seven moderators and effect sizes. The results demonstrated that the effects of protein-carbohydrate supplements showed statistical significance in comparison to the placebo group [μ(SMD): 0.57, 95% CI: 0.2 to 0.93] in enhancing endurance performance. Pure protein supplements demonstrated statistically significant effects compared to the placebo group in both endurance performance [μ(SMD): 0.37, 95% CI: 0.02 to 0.71] and muscle strength [μ(SMD): 0.72, 95% CI: 0.18 to 1.27]. For post-exercise recovery, pure protein supplements also showed statistically significant effects compared to carbohydrate supplements for maintaining glycogen resynthesis [μ(SMD): 0.83, 95% CI: 0.21 to 1.46]. However, the results indicated that all significant effects were observed in randomized controlled trials where the energy intake between the intervention and control groups was not matched. The effects of protein supplementation on athletic performance and post-exercise recovery appear to be limited. Protein supplements showed beneficial effects compared to no supplementation. However, all statistically significant results were derived from studies in which energy intake was not matched between groups. This suggests that the observed benefits may not be attributable to protein per se. An additional intake of 1 g/kg/day of protein from supplements, resulting in a total daily protein intake of approximately 2 g/kg/day, appears to be most effective for enhancing athletic performance. Registered at the International Prospective Register of Systematic Reviews (PROSPERO) (identification code CRD42024608194).

Objectives: To characterise the non-linear joint dose–response relationship of accelerometer-measured moderate-to-vigorous physical activity (MVPA) and cardiorespiratory fitness (CRF, estimated as maximal oxygen uptake (VO₂max)) with incident cardiovascular disease (CVD), and to assess causal consistency using Mendelian randomisation (MR). Methods: We conducted a cohort study in the UK Biobank using accelerometer data linked to hospital and death registries. A Cox generalised additive model characterised the joint MVPA–CRF association with incident CVD (atrial fibrillation, myocardial infarction, heart failure (HF) and stroke), adjusting for confounders. We derived a fitness-stratified matrix quantifying the weekly MVPA minutes associated with prespecified relative hazard reductions. Complementary two-sample MR analyses leveraged genome-wide association study summary statistics for device-measured physical activity (PA) traits and CRF to assess potential causal effects on cardiovascular outcomes. Results: Among 17 088 participants, 1233 incident CVD events occurred over a median follow-up of 7.85 years (IQR, 7.39–8.27). A significant non-linear interaction between MVPA and CRF was observed (p30% risk reduction required threefold to fourfold higher volumes (~560–610 min/week). Residual analysis indicated that fitness beyond what MVPA and covariates predicted retained a modest protective association with CVD risk (HR, 0.98 per 1 mL/kg/min; 95% CI 0.97 to 0.99; p<0.001). In MR analyses, genetically proxied higher CRF was associated with lower HF risk (OR, 0.79; 95% CI 0.63 to 0.99), whereas genetic evidence for PA traits was weaker and less consistent. Conclusion: Current MVPA guidelines provide a universal but modest safety margin, whereas optimal cardiovascular protection may require substantially higher activity volumes. The fitness-stratified prescription matrix offers quantitative behavioural targets, and genetic findings reinforce the independent importance of CRF in cardiovascular risk reduction.