Effects Of Caffeine On Peak And Mean Power Outputs In A 30-second Wingate Test

What is the purpose of your study and what did you expect to find?
Explain why you expect to see this outcome (you must incorporate the underlying physiological mechanisms in your answer).
Describe two studies that have investigated this area and help you explain your hypothesis and explain how they relate to your study
What are the independent and dependent variables in your study?
Describe what you did in your study and explain why you chose that specific approach.  Points to consider: exercise modality, duration and intensity, outcome variables measured (e.g. heart rate, oxygen consumption)
What risks, if any, are involved in the tests you selected to use?  How did you mitigate these risks?
Describe what you found in your experiment (5 marks).
Were your results what you expected? Explain why, based on your knowledge of the underlying physiology. Do they agree or disagree with what is in the literature - provide examples? Provide possible explanations for any differences
Were there any limitations in your experimental design? What would you change if you were to do the experiment again? Explain why

There is an abundance of scientific literature on show displaying the effects of caffeine and its physiological response in exercise performance, both aerobic and to a less extent, anaerobic. A meta-analysis on caffeine ingestion on anaerobic performance using the Wingate across 16 studies, concluded that both mean power and peak power displayed a significant increase upon ingestion of caffeine in comparison to placebo ingestion (Grgic, 2018). Although it is established that there is definitely an increase in anaerobic performance through caffeine ingestion, most participants involved in these studies are of an elite level. Moreover, little effort has been put into the non-elite category of this study, which gives an identification of purpose in my study as the participants involved are at a non-elite level, building on that, it is known that power output is most predictive in elite athletes (Lorenz, Reiman, Lehecka & Naylor, 2013), however the results of the study should clarify that there will be an increase in both mean and peak power followed by the intake of caffeine in a 30 second anaerobic Wingate test. 

Astorino & Roberson (2010) found out that there is an increase in the force of skeletal muscle contraction due to a large dose of supplementing with caffeine. They also found that caffeine enhances the release of calcium from the sarcoplasmic reticulum membrane, without affecting the rate of calcium reuptake. As a result, the potential for the binding of calcium to troponin is much greater, resulting in an increase in actin-myosin filament cross bridging which in turn will result in greater force production by the muscle.

It was expected that mean power performance would be improved upon the use of caffeine as an ergogenic aid, as it is commonly used as a method to improve endurance amongst athletes. Ribeiro & Sebastiao (2010) suggest that caffeine acts as an antagonist towards adenosine receptors, meaning as it binds to the receptors, it halts the binding of adenosine, which stimulates the central nervous system. This stimulation of the CNS has been shown to result in the masking/delaying of fatigue during exercise. This masking of fatigue should allow for prolonged performance, which should allow for an improvement in mean power performance.

A research was conducted by Woolf, Bidwell, & Carlson (2008) which tested the effects of a supplement caffeine against a placebo supplement to determine the effects on factors of performance as an ergogenic aid such as outputs of peak power. The research majorly aimed at determining whether caffeine, as an ergogenic aid had an effect that is significant on the output power by using a 30s Wingate test as a means of determining power output. The research entailed 18 male athletes, with a mean BMI of 26.4 and a mean age of 24.1. The athletes were brought in for testing twice in two occasion a week apart. The participants had to fast 8-12 hours and abstain from products which had caffeine for 48 hours prior to the testing. Prior to the test, the participants would either intake a caffeine (5.0mg/kg BW) or a placebo supplement (carbohydrate, 0.125g/kg BW). The participants also had to partake in a warm-up protocol which consisted of static and dynamic stretches.  The participants began their Wingate test after an hour from taking the supplement and cycled till they reached their maximum speed. Resistance was set and they completed the maximum effort test for 30 seconds. The participants did this o both sessions with caffeine supplement on one of the testing day and the placebo supplement on the other. The testing was completed in a double blind formats so that there is no misinformation and also to increase the overall accuracy of the testing. The study revealed that there was a significant improvement in the peak power in the caffeine trial as opposed to the placebo trial as the caffeine supplement has a value of 0.024 when testing for the output of the peak power. On the other hand, testing for the mean power output revealed that there was a high score in the caffeine stage though it seemed negligible as there was an insignificant improvement with the p-vale (p = 0.110). The caffeine trial had an overall improvement of 78% of the participants. Though these results are not absolutely in line with the results that we had gathered, it still supports the hypothesis that there is a significant in increase in peak power output due to the caffeine supplementation.

Expected Outcome

Grgic (2017) carried out a study with the aim of determining the effects of ingesting caffeine on anaerobic power performance on a 30s Wingate test using the techniques of meta-analytic statistical. 16 studies were found to meet the benchmarks with a collective number of 246 participants. Thus, a standardised mean differences (SMD) for mean and peak power outputs were carried out throughout the study. The outcomes of the meta-analysis therefore showed that there was a significant difference between caffeine trials and placebo trails output power (p-value = 0.005). The output of the peak power revealed a significant difference between the caffeine trails and the placebo trails (p = 0.006). The results presented therefore indicate that ingestion of caffeine can enhance both the peak and the mean power output performed on the Wingate test by an additional 3% and 4% respectively. The meta-analysis therefore adds on to the current evident presented that caffeine consumption can improve the anaerobic performance components.

This research involved eight elite athletes between the ages of 20 to 24 with a mean age of 21.5 ± 1.2 years. This included eight males with a mean height of 179.13 ± 6.06cm and a mean weight of 83.88 ± 14.54kg. No prerequisites were required to take part in this study and those with any medical conditions or injuries were excluded from the experiment. 

The dependant variables being controlled during this research were the peak power and mean power outputs produced following a 30 second Wingate test. The independent variable was the use of ‘No-doz’ an oral caffeine supplement and the use of ‘Glucodin’ a glucose tablet, used as a placebo. The independent variables were provided in a conceived fashion, with either 200mg of the caffeine supplement or the placebo being administered to each participant.

The experiment involved of a total of 8 participants who performed a maximal Wingate test after the consumption of either a Caffeine Tablet or a Glucose Tablet (which was used in place for a placebo). Once again, clients were first asked to complete an ESSA pre-screening tool and a consent form in order to have knowledge of anything issues that may prevent them from performing the experiment. The pre-screening tool and consent form also reduce the chances of any injuries occurring whilst on the Wingate Cycle. During the first week of testing and once the clients completed the ESSA pre-screening tool and consent form, they were given either a Caffeine Tablet or a Glucose Tablet without them knowing which tablet they are consuming. The participants were then given 1 hour after the consumption of the table that they were given without knowing which it was. At the commencement of the hour, the participants performed the maximal Wingate test on the lode bike for 30 seconds. The data that was taken from the computer application linked to the Wingate bike were Torque (Nm), Time to Peak Power (seconds), Mean Power (Watts), Minimum Power (Watts), Peak Power/Body Mass (Watts/kg), Rate to Fatigue (Watts/seconds), and Mean Power/Body Mass (Watts/kg). Two days later, participants once again came in to perform the same protocol on the Wingate Bike. However, they were given the opposite of what they were given in the previous testing week. The same data from the first week was once again taken after the maximal Wingate Test.

Previous studies in this area

Any individual with prior health issues or injuries were unable to partake in this investigation, and they were identified with the use of the ESSA pre-screening test and a signed consent/waiver form used to acknowledge that the participants are aware of any dangers with this study.

Sanders (2015) states that due to the caffeine’s ability to block the binding of adenosine to its receptors, it can result in the build-up of depressive behaviours amongst participants, particularly those who are irregular consumers of caffeine. Therefore in order to mitigate this risk, we have limited the amount of caffeine to approximately 200 milligrams.

Analysis

Table 1: Mean and Standard Deviation values for caffeine and placebo on peak and mean power values

it is evident that the peak power may be higher for some when using caffeine while the other it is high under the placebo. To establish the mean difference, the independent t-test results have to be put in consideration. From the experiment was able to establish that there was no mean difference in peak power when using a caffeine supplement (1015 ± 114.24) or the placebo (991.88 ±107.99), t(7) = - 0.75, p = 0.24.

In figure 2, it can be seen that the mean power for all the participants was higher under caffeine compared to under the placebo. Consequently, it was established by the independent t-test that the mean power was higher while using caffeine (679.50 ± 75.63) compared when one used a placebo (642.38 ± 74.51), t (7) = -6.99, p = 0.00. Consequently, the difference was found out to be statistically significant. 

The research was aimed at finding out the effects of supplementing on caffeine on cycling performance. The main finding was that caffeine significantly increased the mean power when a cyclist ingests caffeine in a 30 second anaerobic Wingate test. On the other hand, caffeine did not increase the peak power when a cyclist ingested caffeine in a 30 second anaerobic Wingate test. The results of this research were the same with Woolf, Bidwell, & Carlson (2008).

However, Glaister et al., (2012) reported no effect of caffeine on the output of the peak or mean power. Regardless, majority of these previous researches used 30 seconds Wingate tests to evaluate the cocaine effects on performance. But, where does the discrepancies in the research findings come from? It is reported that peak power output is lower in 30 seconds versus 10 seconds Wingate tests even in elite athletes. A factor that is attributed to subconscious pacing effects (Bath et al., 2012). Fixed torque protocols of 10 seconds and 15 seconds have failed to find caffeine effect on performance of sprint cycling (Glaister et al., 2012). This is attributed to the possibility of interplay between sprint duration and torque which is responsible for the discrepant finding in other previous researches. Caffeine supplementation has ergogenic effects which are considered to arise from the adenosine receptors antagonism thereby leading to pain suppression, an increase in motor unit firing rates, and neurotransmitter release. 

Participants’ description

Though regarded to as the anaerobic power test benchmark, the Wingate test has some limitations. The study used a 30 second Wingate test. However, there are conflicting literature which suggest that seconds is not the best. Driss & Vandewalle (2013) stated that a 30 - 90 seconds test is too short to establish the critical power. A 3 minute test would be more suitable. On the other hand, Andre et al., (2015) is opinionated that 30 seconds is the perfect time to develop critical power.

Moreover, the study was done in a lab. As a result, this may impact the performer negatively since a test outside the conditions of the lab would have produced different results. Since this is not ecologically study, a future experiment would have to consider doing the tests outside. 

References

Andre, Thomas, Matt Green, Joshua Gann, Eric O'Neal, and Tom Coates. "Effects of caffeine on repeated upper/lower body Wingates and handgrip performance." International Journal of Exercise Science 8, no. 3 (2015): 5.

Astorino, T. A., & Roberson, D. W. (2010). Efficacy of acute caffeine ingestion for short-term high-intensity exercise performance: a systematic review. The Journal of Strength & Conditioning Research, 24(1), 257-265.

Bath, D., Turner, L. A., Bosch, A. N., Tucker, R., Lambert, E. V., Thompson, K. G., & Gibson, A. S. C. (2012). The effect of a second runner on pacing strategy and RPE during a running time trial. International journal of sports physiology and performance, 7(1), 26-32.

Driss, T., & Vandewalle, H. (2013). The measurement of maximal (anaerobic) power output on a cycle ergometer: a critical review. BioMed research international, 2013.

Glaister, M., Patterson, S. D., Foley, P., Pedlar, C. R., Pattison, J. R., & McInnes, G. (2012). Caffeine and sprinting performance: dose responses and efficacy. The Journal of Strength & Conditioning Research, 26(4), 1001-1005.

Grgic, J. (2018). Caffeine ingestion enhances Wingate performance: a meta-analysis. European journal of sport science, 18(2), 219-225. 

Lorenz, D. S., Reiman, M. P., Lehecka, B. J., & Naylor, A. (2013). What performance characteristics determine elite versus nonelite athletes in the same sport?. Sports health, 5(6), 542-547.

Ribeiro, J. A., & Sebastiao, A. M. (2010). Caffeine and adenosine. Journal of Alzheimer's Disease, 20(s1), S3-S15.

Sanders, L. (2015). Body & brain: Caffeine resets body's circadian clock: After?dinner coffee could induce 40?minute delay, study shows. Science News, 188(8), 8-8.

Woolf, K., Bidwell, W. K., & Carlson, A. G. (2008). The effect of caffeine as an ergogenic aid in anaerobic exercise. International Journal of Sports Nutrition and Exercise Metabolism, 18, 412429.