Med Sci Sports Exerc. 2010 Apr 22. [Epub ahead of print]
Effect of Two Doses of Caffeine on Muscular Function during Isokinetic Exercise.
Astorino TA, Terzi MN, Roberson DW, Burnett TR.
1Department of Kinesiology, CSU-San Marcos, San Marcos, CA; 2Department of Kinesiology, San Diego State University-San Diego, CA.
Abstract
ABSTRACT: Studies provide equivocal results regarding the ergogenic properties of caffeine during high intensity exercise. PURPOSE:: The primary aim of this study was to examine the effects of two doses of caffeine on peak/average torque, power output, and total work of the knee extensors and flexors during two bouts of high-intensity exercise. METHODS:: Fifteen active men (mean age and body mass = 26.4 +/- 3.9 yr and 82.7 +/- 2.9 kg) initially completed a familiarization bout on the isokinetic dynamometer, followed by three subsequent trials separated by at least 48 h. Exercise consisted of two bouts of 40 repetitions of maximal knee extension and flexion of the dominant leg at a contraction velocity equal to 180 deg/s. Prior to each trial, subjects abstained from caffeine intake and intense exercise for 48 h. Treatment order (5 mg/kg, 2 mg/kg of anhydrous caffeine, or placebo) was randomly assigned to subjects using a single-blind, counterbalanced, crossover design. A 3 (treatment) X 2 (sets) analysis of variance with repeated measures was used to detect differences in performance across treatment and time. RESULTS:: Compared to placebo, caffeine significantly (p < 0.05) enhanced peak knee flexion torque, knee extension/flexion total work, and knee extension/flexion power in bout 1 with no effect in bout 2. Only the 5 mg/kg dose of caffeine improved performance, with the magnitude of performance improvement ranging from 5 - 8 %. CONCLUSIONS:: Data suggest that a relatively high (5 mg/kg body weight) but not low (2 mg/kg body weight) caffeine dose is ergogenic for maximal knee extension/flexion exercise.
PMID: 20421833 [PubMed - as supplied by publisher]
J Int Soc Sports Nutr. 2010 May 14;7(1):18. [Epub ahead of print]
Caffeine enhances upper body strength in resistance-trained women.
Goldstein ER, Jacobs PL, Whitehurst M, Penhollow T, Antonio J.
Abstract
ABSTRACT: BACKGROUND: Research has indicated that low-to-moderate dosages of caffeine supplementation are ergogenic for sustained endurance efforts as well as high-intensity exercise. The effects of caffeine supplementation on strength-power performance are equivocal, with some studies indicating a benefit and others demonstrating no change in performance. The majority of research that has examined the effects of caffeine supplementation on strength-power performance has been carried out in both trained and untrained men. Therefore, the purpose of this study was to determine the acute effects of caffeine supplementation on strength and muscular endurance in resistance-trained women. METHODS: In a randomized manner, 15 women consumed caffeine (6 mg/kg) or placebo (PL) seven days apart. Sixty min following supplementation, participants performed a one-repetition maximum (1RM) barbell bench press test and repetitions to failure (RF) at 60% of 1RM. Heart rate (HR) and blood pressure (BP) were assessed at rest, 60 minutes post-consumption, and immediately following completion of repetitions to failure. RESULTS: Repeated measures ANOVA indicated a significantly greater bench press maximum with caffeine (p[less than or equal to]0.05) (52.9 +/- 11.1 kg vs. 52.1 +/- 11.7 kg) with no significant differences between conditions in 60% 1RM repetitions (p=0.81). Systolic blood pressure was significantly greater post-exercise, with caffeine (p<0.05) (116.8 +/- 5.3 mmHg vs. 112.9 +/- 4.9 mmHg). CONCLUSIONS: These findings indicate a moderate dose of caffeine may be sufficient for enhancing strength performance in resistance-trained women.
PMID: 20470411 [PubMed - as supplied by publisher]Free Article
And to finish
http://www.nutrifit.co.uk/Conference_Sa ... eatine.pdf
