scispace - formally typeset
Search or ask a question
Author

Zuowei Zhao

Bio: Zuowei Zhao is an academic researcher. The author has contributed to research in topics: Adenosine & Caffeine. The author has an hindex of 1, co-authored 1 publications receiving 416 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: Testing the hypothesis that blockade of central nervous system (CNS) adenosine receptors may explain the beneficial effect of caffeine on fatigue suggests that caffeine can delay fatigue through CNS mechanisms, at least in part by blocking adenosines receptors.
Abstract: Caffeine ingestion can delay fatigue during exercise, but the mechanisms remain elusive. This study was designed to test the hypothesis that blockade of central nervous system (CNS) adenosine recep...

459 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: Experimental approaches that focus on identifying the mechanisms that limit task failure rather than those that cause muscle fatigue are reviewed, providing insight into the rate‐limiting adjustments that constrain muscle function during fatiguing contractions.
Abstract: Much is known about the physiological impairments that can cause muscle fatigue. It is known that fatigue can be caused by many different mechanisms, ranging from the accumulation of metabolites within muscle fibres to the generation of an inadequate motor command in the motor cortex, and that there is no global mechanism responsible for muscle fatigue. Rather, the mechanisms that cause fatigue are specific to the task being performed. The development of muscle fatigue is typically quantified as a decline in the maximal force or power capacity of muscle, which means that submaximal contractions can be sustained after the onset of muscle fatigue. There is even evidence that the duration of some sustained tasks is not limited by fatigue of the principal muscles. Here we review experimental approaches that focus on identifying the mechanisms that limit task failure rather than those that cause muscle fatigue. Selected comparisons of tasks, groups of individuals and interventions with the task-failure approach can provide insight into the rate-limiting adjustments that constrain muscle function during fatiguing contractions.

1,050 citations

Journal ArticleDOI
TL;DR: The scientific literature does not support caffeine-induced diuresis during exercise, or any harmful change in fluid balance that would negatively affect performance, and the literature is equivocal when considering the effects of caffeine supplementation on strength-power performance.
Abstract: Position Statement: The position of The Society regarding caffeine supplementation and sport performance is summarized by the following seven points: 1.) Caffeine is effective for enhancing sport performance in trained athletes when consumed in low-to-moderate dosages (~3-6 mg/kg) and overall does not result in further enhancement in performance when consumed in higher dosages (≥ 9 mg/kg). 2.) Caffeine exerts a greater ergogenic effect when consumed in an anhydrous state as compared to coffee. 3.) It has been shown that caffeine can enhance vigilance during bouts of extended exhaustive exercise, as well as periods of sustained sleep deprivation. 4.) Caffeine is ergogenic for sustained maximal endurance exercise, and has been shown to be highly effective for time-trial performance. 5.) Caffeine supplementation is beneficial for high-intensity exercise, including team sports such as soccer and rugby, both of which are categorized by intermittent activity within a period of prolonged duration. 6.) The literature is equivocal when considering the effects of caffeine supplementation on strength-power performance, and additional research in this area is warranted. 7.) The scientific literature does not support caffeine-induced diuresis during exercise, or any harmful change in fluid balance that would negatively affect performance.

482 citations

Journal ArticleDOI
TL;DR: The present review focuses on the effects of caffeine on striatal signal transduction and on their involvement in caffeine-mediated motor stimulation.
Abstract: The popularity of caffeine as a psychoactive drug is due to its stimulant properties, which depend on its ability to reduce adenosine transmission in the brain. Adenosine A(1) and A(2A) receptors are expressed in the basal ganglia, a group of structures involved in various aspects of motor control. Caffeine acts as an antagonist to both types of receptors. Increasing evidence indicates that the psychomotor stimulant effect of caffeine is generated by affecting a particular group of projection neurons located in the striatum, the main receiving area of the basal ganglia. These cells express high levels of adenosine A(2A) receptors, which are involved in various intracellular processes, including the expression of immediate early genes and regulation of the dopamine- and cyclic AMP-regulated 32-kDa phosphoprotein DARPP-32. The present review focuses on the effects of caffeine on striatal signal transduction and on their involvement in caffeine-mediated motor stimulation.

475 citations

Journal ArticleDOI
TL;DR: Regression analysis revealed that RPE obtained during exercise could account for ∼29% of the variance in the improvement in exercise performance and this may partly explain the subsequent ergogenic effects of caffeine on performance.
Abstract: 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 56% (95% CI (confidence interval), -45% to -67%), with an equivalent RPE ES of -047 (95% CI, -035 to -059) These values were significantly greater (P<005) than RPE obtained at the end of exercise (RPE % change, 001%; 95% CI, -19 to 20%; RPE ES, 000, 95% CI, -017 to 017) In addition, caffeine improved exercise performance by 112% (95% CI; 46-178%) 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

445 citations

Journal ArticleDOI
TL;DR: Repeated administration of caffeine is an effective strategy to maintain physical and cognitive capabilities, since most real-world activities require complex decision making, motor processing and movement.

436 citations