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Background: Effects of resistance training on muscle strength and hypertrophy are wellestablished in adults and younger elderly. However, less is currently known about these effects in the very elderly (i.e., 75 years of age and older).Objective: To examine the effects of resistance training on muscle size and strength in very elderly individuals.Methods: Randomized controlled studies that explored the effects of resistance training in very elderly on muscle strength, handgrip strength, whole-muscle hypertrophy, and/or muscle fiber hypertrophy were included in the review. Meta-analyses of effect sizes (ESs) were used to analyze the data.Results: Twenty-two studies were included in the review. The meta-analysis found a significant effect of resistance training on muscle strength in the very elderly (difference in ES = 0.97; 95% confidence interval [CI]: 0.50, 1.44; p = 0.001). In a subgroup analysis that included only the oldest-old participants (80+ years of age), there was a significant effect of resistance training on muscle strength (difference in ES = 1.28; 95% CI: 0.28, 2.29; p = 0.020). For handgrip strength, we found no significant difference between resistance training and control groups (difference in ES = 0.26; 95% CI: -0.02, 0.54; p = 0.064). For wholemuscle hypertrophy, there was a significant effect of resistance training in the very elderly (difference in ES = 0 30; 95% CI: 0.10, 0.50; p = 0.013). We found no significant difference in muscle fiber hypertrophy between resistance training and control groups (difference in ES = 0.33; 95% CI: -0.67, 1.33; p = 0.266). There were minimal reports of adverse events associated with the training programs in the included studies. 3 Conclusions: We found that very elderly can increase muscle strength and muscle size by participating in resistance training programs. Resistance training was found to be an effective way to improve muscle strength even among the oldest-old. Key points: ►We found that very elderly adults can increase their muscle strength and size by participating in resistance training programs. ►These effects were observed with resistance training interventions that generally included low weekly training volumes and frequencies. ►There were minimal reports of adverse events associated with the training programs.

Purpose: To examine the acute effects of 3 doses of caffeine on upper- and lower-body ballistic exercise performance and to explore if habitual caffeine intake affects the acute effects of caffeine ingestion on ballistic exercise performance. Methods: Twenty recreationally active male participants completed medicine-ball-throw and vertical-jump tests under 4 experimental conditions (placebo and 2, 4, and 6 mg·kg−1 of caffeine). Results: One-way repeated-measures analysis of variance (ANOVA) with subsequent post hoc analyses indicated that performance in the medicine-ball-throw test improved, compared with placebo, only with a 6 mg·kg−1 dose of caffeine (P = .032). Effect size, calculated as the mean difference between the 2 measurements divided by the pooled SD, amounted to 0.29 (+3.7%). For the vertical-jump test, all 3 caffeine doses were effective (compared with placebo) for acute increases in performance (P values .022–.044, effect sizes 0.35–0.42, percentage changes +3.7% to +4.1%). A 2-way repeated-measures ANOVA indicated that there was no significant group × condition interaction effect, suggesting comparable responses between low (≤100 mg·d−1) and moderate to high (>100 mg·d−1) caffeine users to the experimental conditions. Conclusion: Caffeine doses of 2, 4, and 6 mg·kg−1 seem to be effective for acute enhancements in lower-body ballistic exercise performance in recreationally trained male individuals. For the upper-body ballistic exercise performance, only a caffeine dose of 6 mg·kg−1 seems to be effective. The acute effects of caffeine ingestion do not seem to be affected by habitual caffeine intake; however, this requires further exploration.

Purpose: To explore the effects of 3 doses of caffeine on muscle strength and muscle endurance. Methods: Twenty-eight resistance-trained men completed the testing sessions under 5 conditions: no-placebo control, placebo control, and with caffeine doses of 2, 4, and 6 mg·kg−1. Muscle strength was assessed using the 1-repetition-maximum test; muscle endurance was assessed by having the participants perform a maximal number of repetitions with 60% 1-repetition maximum. Results: In comparison with both control conditions, only a caffeine dose of 2 mg·kg−1 enhanced lower-body strength (d = 0.13–0.15). In comparison with the no-placebo control condition, caffeine doses of 4 and 6 mg·kg−1 enhanced upper-body strength (d = 0.07–0.09) with a significant linear trend for the effectiveness of different doses of caffeine (P = .020). Compared with both control conditions, all 3 caffeine doses enhanced lower-body muscle endurance (d = 0.46–0.68). For upper-body muscle endurance, this study did not find significant effects of caffeine. Conclusions: This study revealed a linear trend between the dose of caffeine and its effects on upper-body strength. The study found no clear association between the dose of caffeine and the magnitude of its ergogenic effects on lower-body strength and muscle endurance. From a practical standpoint, the magnitude of caffeine’s effects on strength is of questionable relevance. A low dose of caffeine (2 mg·kg−1)—for an 80-kg individual, the dose of caffeine in 1–2 cups of coffee—may produce substantial improvements in lower-body muscle endurance with the magnitude of the effect being similar to that attained using higher doses of caffeine.

Manuscript word count: 4755 Number of figures: 4 Number of tables: 3 Does aerobic training promote the same skeletal muscle hypertrophy as resistance 24 training? A systematic review and meta