Effects of caffeine ingestion on rating of perceived exertion during and after exercise: a meta-analysis

The purpose of this study was to use the meta-analytic approach to examine the effects of caffeine ingestion on ratings of perceived exertion (RPE). Twenty-one studies with 109 effect sizes (ESs) met the inclusion criteria. Coding incorporated RPE scores obtained both during constant load exercise (n=89) and upon termination of exhausting exercise (n=20). In addition, when reported, the exercise performance ES was also computed (n=16). In comparison to placebo, caffeine reduced RPE during exercise by 5.6% (95% CI (confidence interval), -4.5% to -6.7%), with an equivalent RPE ES of -0.47 (95% CI, -0.35 to -0.59). These values were significantly greater (P<0.05) than RPE obtained at the end of exercise (RPE % change, 0.01%; 95% CI, -1.9 to 2.0%; RPE ES, 0.00, 95% CI, -0.17 to 0.17). In addition, caffeine improved exercise performance by 11.2% (95% CI; 4.6-17.8%). Regression analysis revealed that RPE obtained during exercise could account for approximately 29% of the variance in the improvement in exercise performance. The results demonstrate that caffeine reduces RPE during exercise and this may partly explain the subsequent ergogenic effects of caffeine on performance.

Adrenoreceptors, endothelial function, and lipid profile: effects of atenolol, doxazosin, and carvedilol

BACKGROUND

The use of effective blood-pressure-lowering drugs has not achieved the expected reduction in the incidence of ischaemic heart disease in hypertensive patients. This study examined the cardiovascular effects of adrenergic blockade (alpha or beta, or both) and its effect on the fibrinolytic response of the endothelium to anoxia and lipoprotein metabolism in 78 hypertensive patients with ischaemic heart disease.

METHODS

All patients had stable angina on positive exercise testing and silent ischaemia on 24 h Holter monitoring at baseline and 6 months after effective blood-pressure-lowering treatment with the selective beta-blocker atenolol, the alpha 1-inhibitor doxazosin, or the dual-action drug carvedilol.

RESULTS

Atenolol increased the effort time (P < 0.05), total ischaemia (P < 0.05), and the number of ischaemic episodes (P < 0.05). It reduced the lipoprotein ratio (P < 0.05) but did not modify the fibrinolytic activity of the endothelium. Doxazosin increased the fibrinolytic index (ratio of plasminogen activator to its main inhibitor) before (P < 0.05) and after anoxia (P < 0.0001) and the lipoprotein ratio (P < 0.001), without an anti-ischaemic effect. Carvedilol increased the effort time (P < 0.05), reducing total ischaemia (P < 0.05), the number of ischaemic episodes (P < 0.01), and increasing the post-anoxia fibrinolytic index (P < 0.05) without modifying the lipid profile.

CONCLUSIONS

At antihypertensive equipotent doses, the inhibition of alpha 1-receptors improves the endothelial fibrinolytic activity and the lipid profile. beta-Blockade has an anti-ischaemic action, but reduces the lipoprotein ratio (ApoA/ApoB) and does not improve endothelial fibrinolytic activity.