Background: Creatine supplementation is widely used to enhance exercise performance, mainly resistance training adaptations, yet its differential effects on upper- and lower-body strength and muscular power remain unclear across populations. Objective: This systematic review and meta-analysis aimed to quantify the effects of creatine supplementation in studies that included different exercise modalities or no exercise on upper- and lower-body muscular strength and power in adults. Methods: A comprehensive search of PubMed, Scopus, and Web of Science was conducted through 21 September 2024 to identify randomized controlled trials evaluating the effects of creatine supplementation on strength (bench/chest press, leg press, and handgrip) and power (upper and lower body). Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated using random-effects modeling. Subgroup analyses examined the influence of age, sex, training status, dose, duration, and training frequency. Results: A total of 69 studies with 1937 participants were included for analysis. Creatine plus resistance training produced small but statistically significant improvements in bench and chest press strength [WMD = 1.43 kg, p = 0.002], squat strength [WMD = 5.64 kg, p = 0.001], vertical jump [WMD = 1.48 cm, p = 0.01], and Wingate peak power [WMD = 47.81 Watts, p = 0.004] when compared to the placebo. Additionally, creatine supplementation combined with exercise training revealed no significant differences in handgrip strength [WMD = 4.26 kg, p = 0.10] and leg press strength [WMD = 3.129 kg, p = 0.11], when compared with the placebo. Furthermore, subgroup analysis based on age revealed significant increases in bench and chest press [WMD = 1.81 kg, p = 0.002], leg press [WMD = 8.30 kg, p = 0.004], and squat strength [WMD = 6.46 kg, p = 0.001] for younger adults but not for older adults. Subgroup analyses by sex revealed significant increases in leg press strength [WMD = 9.79 kg, p = 0.001], squat strength [WMD = 6.43 kg, p = 0.001], vertical jump [WMD = 1.52 cm, p = 0.04], and Wingate peak power [WMD = 55.31 Watts, p = 0.001] in males, but this was not observed in females. Conclusions: This meta-analysis indicates that creatine supplementation, especially when combined with resistance training, significantly improves strength in key compound lifts such as the bench or chest press and squat, as well as muscular power, but effects are not uniform across all measures. Benefits were most consistent in younger adults and males, while older adults and females showed smaller or non-significant changes in several outcomes. No overall improvement was observed for handgrip strength or leg press strength, suggesting that the ergogenic effects may be more pronounced in certain multi-joint compound exercises like the squat and bench press. Although the leg press is also a multi-joint exercise, results for this measure were mixed in our analysis, which may reflect differences in study design, participant characteristics, or variability in testing protocols. The sensitivity of strength tests to detect changes appears to vary, with smaller or more isolated measures showing less responsiveness. More well-powered trials in underrepresented groups, particularly women and older adults, are needed to clarify population-specific responses.

Context: Intermittent fasting (IF) and calorie restriction (CR) have gained interest as dietary strategies due to their potential for weight loss and multiple metabolic benefits. These strategies are often accompanied by exercise in an attempt to improve body composition and physical performance. However, further research is crucial to understanding whether or not physical performance is affected by the expected weight loss and related body composition changes in individuals on IF and CR, even when exercise is combined. Objective: We aimed to systematically evaluate the effects of IF and CR on exercise performance and body composition in adults aged 18 to 65 years. Data Source: A systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A systematic review was conducted up to April 2024 by searching electronic databases, including PubMed, Web of Science, and Scopus. There was no limit on publication dates. Data Extraction: The search explored the impact of IF and CR combined with exercise vs. exercise alone (control) on exercise performance outcomes: VO_2max, handgrip strength, bench press strength, knee extensor strength, leg press strength, countermovement jump (CMJ), 400 m walk test, and gait speed; body weight, body mass index (BMI), and body composition: fat-free mass (FFM), fat mass (FM), and body fat percentage (BFP). Analyses included calculation of weighted mean difference (WMD), standardized mean difference (SMD), and 95% confidence intervals (CIs) to assess outcomes. Data Analysis: The meta-analysis included a total of 35 studies, ranging from 4 to 52 weeks and involving 1266 participants. The results showed that IF (hypocaloric or eucaloric diet) and CR combined with exercise increased handgrip strength [WMD = 1.707 kg, p = 0.01] compared to exercise alone. Moreover, IF and CR combined with exercise did not significantly affect VO_2max [SMD = 0.005, p = 0.94], bench press strength [WMD = 0.377 kg, p = 0.778], knee extensor strength [WMD = −4.729 kg, p = 0.12], leg press strength [WMD = −2.874 kg, p = 0.415], countermovement jump [WMD = −0.226 cm, p = 0.80], 400 m walk test performance [WMD = −8.794 s, p = 0.06], or gait speed [WMD = 0.005 m/s, p = 0.82] compared to exercise alone. Moreover, IF and CR combined with exercise decreased body weight [WMD = −4.375 kg, p = 0.001], BMI [WMD = −1.194 kg·m⁻², p = 0.001], FFM [WMD = −1.653 kg, p = 0.001], FM [WMD = −2.858 kg, p = 0.001], BFP [WMD = −0.826%, p = 0.001] compared to exercise alone. Conclusions: IF (hypocaloric or eucaloric) and CR can be effectively integrated into exercise training without negatively impacting most measures of physical performance, while significantly enhancing weight loss and adiposity-related outcomes. The findings from this meta-analysis involving both athletes and non-athletes suggest that weight loss induced by IF and CR combined with exercise does not necessarily result in reduced physical performance. In real-world scenarios, however, different outcomes are conceivable, as body composition, physical capacity, diet and exercise can vary considerably based on individual conditions.

Background and Aims: The combination of resistance training (RT) with a ketogenic diet (KD) is acknowledged as an effective strategy to improve body composition. The present meta-analysis aimed to investigate the combined effect of RT and KD on body composition factors. Materials and Methods: A comprehensive search was conducted in Web of ...