Background: Caffeine is one of the most popular ergogenic aids consumed by athletes. Caffeine’s ergogenic effect has been generally explained by its ability to bind to adenosine receptors, thus modulating pain and reducing perceived exertion. Another pharmacological agent that may improve performance due to its analgesic proprieties is paracetamol. This study aimed to explore the effects of caffeine, paracetamol, and caffeine + paracetamol consumption on muscular endurance, strength, power, anaerobic endurance, and jumping performance. Methods: In this randomized, crossover, double-blind study, 29 resistance-trained participants (11 men and 18 women) ingested either a placebo, caffeine (3 mg/kg), paracetamol (1500 mg) or caffeine + paracetamol 45 min before the testing sessions. The testing sessions included performing the bench press exercise with 75% of one-repetition maximum to momentary muscular failure, isokinetic knee extension and flexion at angular velocities of 60°/sec and 180°/sec, Wingate, and countermovement jump (CMJ) tests. Results: Compared to placebo, isolated caffeine ingestion increased the number of repetitions performed in the bench press (p = 0.005; d = 0.42). Compared to placebo, isolated caffeine ingestion and/or caffeine + paracetamol consumption was ergogenic for strength (torque), muscular endurance (total work), or power in the isokinetic assessment, particularly at slower angular velocities (p = 0.027 to 0.002; d = 0.16 to 0.26). No significant differences between the conditions were observed for outcomes related to the Wingate and CMJ tests. Conclusion: This study provided novel evidence into the effectiveness of caffeine, paracetamol, and their combination on exercise performance. We found improvements in muscular endurance, strength, or power only when caffeine was consumed in isolation, or in combination with paracetamol. Isolated paracetamol consumption did not improve performance for any of the analyzed outcomes, thus calling into question its ergogenic potential.

Purpose This study reports the results of a 20-year (2005-2024) follow-up study of two 2-time Olympic and 6-time world champion rowing athletes. To provide a comprehensive picture of adaptations in physiological and performance characteristics to long-term training, we monitored the athletes’ physiological and performance data annually through five 4-year developmental phases. Methods Maximal oxygen uptake (V̇O 2max ), maximal minute power (MMP), and power output corresponding to anaerobic threshold (PAT) were derived from a ramp-wise exercise test on a rowing ergometer. Additionally, average power output sustained during all-out tests over 2000-m and 6000-m on a rowing ergometer was also obtained. Results V̇O 2max peaked at age 22 for Athlete A and at age 25 for Athlete B (at ~7 L·min ⁻¹ ), before stabilizing and then gradually declining to a range of 6.2-6.5 L·min ⁻¹ for both athletes. MMP stabilized in both rowers at values between 550 and 575 W and displayed minimal fluctuations over the final two phases of the study. Additionally, MMP closely resembled the corresponding average power output sustained during the 2000-m all-out tests on a rowing ergometer. Average power output during 2000-m and 6000-m all-out tests showed steady improvements over the monitored phases of the study, with highest power output crew averages for both 2000-m (532 W; 5 min 48 s) and 6000-m (463 W; 18 min 4 s) tests recorded during the last 4-year phase of the assessment. Conclusions Improvements in rowing ergometer performance over 2000-m and 6000-m appear to be largely independent of the multi-year changes in V̇O 2max . Long-term rowing training resulted in continuous improvements in MMP and PAT throughout the monitored phases, which more closely mimicked improvements in rowing ergometer performance.

This study examined caffeine's effects on isokinetic strength, power, and endurance. The sample included 25 young, resistance-trained males. The participants were tested on three occasions , in a control trial (no substance ingestion) and following the ingestion of 6 mg•kg −1 of caffeine or placebo. Exercise tests involved isokinetic knee extension and flexion using angular velocities of 60° s −1 and 180° s −1. Analyzed outcomes included peak torque, average power, and total work. For knee extension at an angular velocity of 60° s −1 , there were significant differences for: (1) peak torque when comparing caffeine vs. control (Hedges' g = 0.22) and caffeine vs. placebo (g = 0.30) and (2) average power when comparing caffeine vs. control (g = 0.21) and caffeine vs. placebo (g = 0.29). For knee extension at an angular velocity of 180° s −1 , there were significant differences for: (1) peak torque when comparing caffeine vs. placebo (g = 0.26), (2) average power when comparing caffeine vs. control (g = 0.36) and caffeine vs. placebo (g = 0.43), and (3) total work when comparing caffeine vs. control (g = 0.33) and caffeine vs. placebo (g = 0.36). Caffeine was not ergogenic for knee flexors in any of the analyzed outcomes. Additionally, there was no significant difference between control and placebo. In summary, caffeine enhances the mechanical output of the knee extensors at lower and higher angular velocities, and these effects are present when compared to placebo ingestion or no substance ingestion (control).

Purpose: To compare the acute effects of caffeine and placebo ingestion with a control condition (i.e., no supplementation) on vertical jump performance. Methods: The sample for this study consisted of 26 recreationally trained males. Following the familiarization visit, the subjects were randomized in a double-blind fashion to three main conditions: (a) placebo, (b) caffeine, and (c) control. Caffeine was administered in a gelatin capsule in the dose of 6 mg∙kg−1 of body weight. Placebo was administered in a gelatin capsule containing 6 mg∙kg−1 of dextrose. Vertical jump performance was assessed using a countermovement jump (CMJ) performed on a force platform. Analyzed outcomes were vertical jump height and maximal power output. Results: For vertical jump height, we observed significant differences between: (a) placebo and control conditions (g = 0.13, 95% confidence interval [CI]: 0.03, 0.24; +2.5%); (b) caffeine and control conditions (g = 0.31, 95% CI: 0.17, 0.50; +6.6%); and, (c) caffeine and placebo conditions (g = 0.19, 95% CI: 0.06, 0.34; +4.0%). For maximal power output, we did not find a significant main effect of condition (p = 0.638). Conclusions: Ingesting a placebo or caffeine may enhance CMJ performance as compared to the control condition, with the effects of caffeine vs. control appearing to be greater than the effects of placebo vs. control. Additionally, caffeine was ergogenic for CMJ height as compared to placebo. Even though caffeine and placebo ingestion improved vertical jump height, we did not find any significant effects of condition on maximal power output generated during take-off.

The aim of this systematic review was to explore the test-retest reliability of isometric mid-thigh pull maximum strength assessment. We searched through five databases to find studies that examined the test-retest reliability of peak force in the isometric mid-thigh pull exercise. From each included study, we extracted intra-class correlation coefficients (ICC) and/or coefficient of variation (CV). The methodological quality of the included studies was evaluated using the COSMIN checklist. A total of 16 good-to-excellent quality studies were included in the review. When considering results from all included studies, ICCs ranged from 0.73 to 0.99 (median ICC = 0.96), where 78% of ICCs were ≥0.90, and 98% of ICCs were ≥0.75. The range of reported CVs was from 0.7% to 11.1% (median CV = 4.9%), where 58% of CVs were ≤5%. Reliability was also good-to-excellent for both relative and absolute peak force and for both bilateral and unilateral isometric mid-thigh pull tests. The majority of studies did not find significant differences between testing sessions. It can be concluded that the isometric mid-thigh pull maximum strength assessment has good-to-excellent test-retest reliability. The isometric mid-thigh pull maximum strength assessment can be used as a reliable test in sports practice and for research purposes.