Caffeine and Performance over Consecutive Days of Simulated Competition

Fett

et al. 2016

AJTCAM

Background: Intense physical training increases oxidative stress and inflammation, resulting into muscle and cellular damage. The aim of this study was to analyze the effect of caffeine supplementation on trained young individuals subjected to two treadmill maximal tests. Materials and Methods: It was a double-blind and crossover study comprising 24 active individuals within the age group 18-30 years. The comparisons were conducted: the effect of exercise (week 1 x 2) and caffeine intake (GC x GP) on thiobarbituric acid (TBARS), interleukin 6 (IL-6), interleukin 10 (IL-10) and superoxide dismutase (SOD) variables during pre-exercise time (30 min. after caffeine or placebo intake) and post-exercise (5 min after treadmill test). Results:The comparison between weeks 1 and 2 showed increase in the first week, in the following items: TBARS, IL-6 and IL-10 in the GC and GP groups. The comparison within the same week showed that GC individuals presented lower post-exercise TBARS values in the first and second weeks; IL-6 presented higher post-exercise values in the GC group in both weeks. The paired analysis comparing pre-and post-exercise, with and without caffeine showed that IL-6 presented higher post-exercise values in the GC group. Conclusion: Caffeine used by athletes can decrease oxidative stress. The increased IL-6 suggest that this ergogenic supplement may stimulate muscle hypertrophy, since IL-6 has myokine effect. However, the caffeine effect on IL-6 level and muscle hypertrophy increase should be better investigated in future studies.

Section: Discussionsupporting

confidence: 92%

The Effect of Caffeine Supplementation on Trained Individuals Subjected to Maximal Treadmill Test

Fett

et al. 2016

AJTCAM

Journal of Caffeine and Adenosine Research

“…However, as those authors did not report body mass for the subjects, an average body mass of 66.8 kg was determined for a mixed group of male and female cross-country skiers based upon previous research. 48,49,57 For the hand cycling study, 39 the article by Conger and Bassett 58 was used to predict metabolic energy expenditure from speed using linear regression. Power output was then estimated based on an assumed gross mechanical efficiency of 12.1% from previous research.…”

Section: Meta-analysismentioning

confidence: 99%

Effects of Caffeine on Time Trial Performance and Associated Physiological Responses: A Meta-Analysis

GlaisterMark

MoirGavin

2019

Background: The aim of this study was to conduct a systematic review and meta-analysis on the effects of caffeine supplementation on time trial performance and associated physiological responses. Methods: A total of 35 studies met the inclusion criteria of adopting double-blind randomized placebocontrolled crossover designs that included a closed-loop time trial ( ‡5 minutes) performed under a caffeine dose of 3-6 mg/kg administered 30-90 minutes beforehand. Meta-analyses were completed using a random-effects model, with effects on time trial performance presented as standardized mean difference (d) and with physiological responses presented as raw mean difference (D). The 95% confidence limits (CL 95 ) were calculated for all estimates. Results: Relative to placebo, caffeine had a positive effect on time trial performance (d = 0.32; CL 95 [0.19-0.44]). Moreover, the effect of caffeine on time trial performance corresponded with increases in heart rate (D = 3.3 beats/min; CL 95 [1.7-4.8]), oxygen uptake (D = 0.09 L/min; CL 95 [0.02-0.17]), blood lactate (D = 1.42 mmol/L; CL 95 [1.09-1.74]), and blood glucose (D = 0.94 mmol/L; CL 95 [0.58-1.30]). In contrast, caffeine had no effect on time trial measures of respiratory exchange ratio (D = 0.01; CL 95 [À0.01 to 0.02]), or ratings of perceived exertion (D = 0.1; CL 95 [À0.1 to 0.3]). Conclusions:The results reveal a clear effect of caffeine on moderate-to high-intensity time trial performance. When considered in conjunction with research using fixed-intensity exercise, the caffeine-induced increase in time trial intensity likely explains all of the associated increases in heart rate and oxygen uptake, and part of the increase in blood lactate and blood glucose.

“…Although there is only one specific study regarding the use of caffeine in a simulated two day sporting competition [51], there are several topical themes around serial use of this common dietary ingredient. Previously, the enhancement of exercise capacity associated with caffeine was believed to be reduced by habitual use, necessitating withdrawal from caffeine for several days to achieve a state of caffeine naivety for both the rigor of scientific study and the optimization of competition benefits [15].…”

Section: Repeated Use Of Supplementsmentioning

confidence: 99%

“…Further research is needed to both identify and investigate such patterns objectively, and to remove the confounding variables that may otherwise affect sleep architecture such as competition arousal, high-intensity exercise and alterations in daily routines. In the meantime, the only available study of repeated use of caffeine in a simulated competition scenario [51] found that modest (3 and 4.5 mg/kg) doses, as recommended in current guidelines for caffeine use in sport, were associated with consistent and significant performance benefits (4–5% enhancement of work done in a cross country skiing time trial) when implemented on two occasions, 24 h apart (Table 4). This benefit occurred despite increased muscle damage and soreness from the first bout undertaken with caffeine, attributed to the greater exercise effort; presumably, the use of caffeine on the second occasions was able to mask these effects [51].…”

Section: Repeated Use Of Supplementsmentioning

confidence: 99%

See 1 more Smart Citation

Practical Issues in Evidence-Based Use of Performance Supplements: Supplement Interactions, Repeated Use and Individual Responses

Burke

2017

Sports Med

Current sports nutrition guidelines recommend that athletes only take supplements following an evidence-based analysis of their value in supporting training outcomes or competition performance in their specific event. While there is sound evidence to support the use of a few performance supplements under specific scenarios (creatine, beta-alanine, bicarbonate, caffeine, nitrate/beetroot juice and, perhaps, phosphate), there is a lack of information around several issues needed to guide the practical use of these products in competitive sport. First, there is limited knowledge around the strategy of combining the intake of several products in events in which performance benefits are seen with each product in isolation. The range in findings from studies involving combined use of different combinations of two supplements makes it difficult to derive a general conclusion, with both the limitations of individual studies and the type of sporting event to which the supplements are applied influencing the potential for additive, neutral or counteractive outcomes. The repeated use of the same supplement in sports involving two or more events within a 24-h period is of additional interest, but has received even less attention. Finally, the potential for individual athletes to respond differently, in direction and magnitude, to the use of a supplement seems real, but is hard to distinguish from normal day to day variability in performance. Strategies that can be used in research or practice to identify whether individual differences are robust include repeat trials, and the collection of data on physiological or genetic mechanisms underpinning outcomes.