Combining caffeine and taurine for improved physical and cognitive performance Original paper

There’s a robust body of evidence demonstrating that supplementing with caffeine (3–6 mg per kg of body weight) can improve aerobic and anaerobic exercise performance.^[1] Whether supplementing with the amino acid taurine improves exercise performance is less clear,^[2] but it’s considered a potential ergogenic (performance-enhancing) supplement due to its various physiological functions in the body, including roles in calcium homeostasis and fat metabolism.^[2] Taurine is also a common component of energy drinks, which contain caffeine and other ingredients and have been shown to enhance exercise performance.^[3] Does a combination of caffeine and taurine improve exercise performance more than either substance alone?

In this randomized crossover trial, 20 elite male boxers (average age of 22) ingested one of four supplemental formulations 60 minutes before completing a Wingate test (a 30-second all-out sprint on a cycle ergometer), followed by a balance test, the Illinois agility test, and the Stroop test (a neuropsychological test):

• CAF: 6 mg of caffeine per kg of body weight
• TAU: 3,000 mg of taurine
• CAF+TAU: 6 mg of caffeine per kg of body weight + 3,000 mg of taurine
• PLA: 300 mg of maltodextrin

All four sessions took place within a 72-hour period. The outcomes assessed were peak power, relative peak power (watts/kg of body weight), average power, minimum power, time to reach peak power, blood lactate levels, and rating of perceived exertion (RPE) during the Wingate test; static and dynamic balance in the dominant and nondominant leg during the balance test; time to finish the Illinois agility test; and reaction time and error rate during the Stroop test.

Compared to PLA, CAF, TAU, and CAF+TAU increased peak power, relative peak power, average power, and minimum power and decreased time to peak power. Compared to PLA, CAF+TAU decreased RPE. Compared to TAU, CAF increased relative peak power, average power, and minimum power, whereas CAF+TAU increased peak power, relative peak power, average power, and minimum power. Compared to CAF, CAF+TAU increased relative peak power and average power.

For the balance test, CAF+TAU improved all balance-related outcomes compared to PLA. For the agility test, CAF, TAU, and CAF+TAU improved performance compared to PLA. For the Stroop test, CAF+TAU improved reaction time compared to TAU, CAF, and PLA. Compared to PLA, CAF, TAU, and CAF+TAU improved error rate.

Peak, average, and minimum power differences between groups

Weight-adjusted peak power between the treatment groups

The Wingate test is a common method used to assess anaerobic exercise performance. In agreement with a 2018 meta-analysis reporting that caffeine improves average and peak power output during the Wingate test to a small extent,^[4] the summarized study found that compared to PLA, CAF increased peak power, relative peak power, average power, minimum power, and time to reach peak power. Caffeine has been consistently shown to enhance a wide range of measures of anaerobic exercise performance,^[1] such as throwing performance,^[5] single and repeated jump height,^[6]and resistance exercise performance,^[7] including 1-repetition maximum strength, muscular endurance, velocity, and power.

While it’s unsurprising that the results of the summarized study provide further support for caffeine’s ergogenic effects, the same cannot necessarily be said for taurine, which also increased peak power, relative peak power, average power, minimum power, and time to reach peak power compared to PLA.

Evidence suggests that taurine improves aerobic exercise performance, particularly in time-to-exhaustion tests,^[8][9] but there is comparatively little evidence to support the idea that taurine enhances anaerobic exercise performance.^[2] In addition, there is good mechanistic rationale to believe that taurine would be more efficacious for aerobic exercise performance than anaerobic exercise performance.

For starters, taurine concentrations appear to be substantially higher in oxidative (slow-twitch) muscle fibers than glycolytic (fast-twitch) muscle fibers,^[10] the former primarily contributing to aerobic exercise performance. Additionally, taurine may improve the function of mitochondria and play a role in increasing the number of mitochondria (i.e., mitochondrial biogenesis).^[10][11][2]

The mitochondria run the show when it comes to aerobic exercise performance. Aerobic metabolism (i.e., the production of energy or ATP in the presence of oxygen) occurs in the mitochondria, with the mitochondria increasing their rates of ATP synthesis to match the metabolic demands of the cell during exercise. Exercise elicits mitochondrial adaptations (i.e., improved function and mitochondrial biogenesis), which in turn improve aerobic exercise performance.^[12] Indeed, mitochondrial content is positively associated with maximal oxygen consumption (VO₂max) and time-trial performance.^[13][14]

Taurine seems to act as a buffering agent in the mitochondria, which helps to maintain biochemical processes, including the efficiency of ATP turnover, during exercise.^[10] Skeletal muscle produces high rates of oxidants during exercise, which impair muscle contractility and promote fatigue, resulting in impaired performance.^[15] Through its role as an antioxidant,^[16] taurine may positively contribute to aerobic exercise performance by mitigating oxidative stress during exercise.

Another way taurine could influence aerobic exercise performance is by modulating fat metabolism.^[17][18] In other words, taurine may increase the breakdown of fat for fuel and reduce the contribution of glycolytic metabolism to energy production. As the depletion of glycogen is associated with fatigue during exercise and impaired performance,^[19] this alteration in fuel utilization is theoretically beneficial.

With respect to anaerobic exercise performance, taurine may improve performance via its role in calcium handling,^[20] as calcium signals muscle contraction to occur. Preliminary evidence suggests that taurine enhances calcium accumulation in the sarcoplasmic reticulum and increases the sensitivity of the force-generating proteins (i.e., actin and myosin) in skeletal muscle.^[21][22][2] Therefore, taurine may enhance muscle force production and power output. Taurine’s potential to mitigate oxidative stress may also positively contribute to power output during exercise, particularly average power output.

Although there is little direct evidence in humans to support the above mechanisms or the idea that taurine enhances anaerobic exercise performance, there is even less evidence that coingesting taurine and caffeine produces ergogenic effects greater than that of either substance alone, which makes the summarized study particularly notable.

Despite this lack of evidence, most energy drinks contain caffeine and taurine, and these two ingredients are proclaimed to be responsible for the effects of energy drinks on exercise performance. The results of one meta-analysis that examined the effects of energy drinks on various aspects of physical performance suggested that higher doses of taurine were associated with greater benefits.^[3]

The summarized study reported that the coingestion of caffeine and taurine may enhance anaerobic exercise performance to a greater degree than either substance alone. Specifically, CAF+TAU increased relative peak power and average power compared to CAF and TAU. An in vitro study using skinned muscle fibers from rats reported that taurine’s effects on force production were augmented by the presence of caffeine.^[23]

There are also several studies in humans that assessed anaerobic exercise performance. In contrast to the summarized study, a 2017 crossover trial that had male team-sport athletes complete three Wingate tests (each separated by 2 minutes of recovery) reported that coingestion of caffeine (5 mg per kg of body weight) and taurine (50 mg per kg of body weight, about 4,300 mg on average) had similar effects on peak power and average power compared to caffeine and taurine alone.^[24]

In a 2021 crossover trial that had female team-sport athletes complete a Wingate test, CAF+TAU (5 mg of caffeine per kg of body weight and 1,000 mg of taurine) increased peak power and average power compared to placebo, but not compared to CAF.^[25] Also, CAF+TAU increased average power compared to TAU, but not peak power. Notably, neither TAU nor CAF increased peak power or average power compared to placebo. A difference between the 2021 study and the summarized study is the relatively low dose of taurine used, which may have influenced the results.

In a third crossover trial published in 2020, coingestion of caffeine (80 mg) and taurine (1,000 mg) did not improve peak power or the maintenance of power output during repeated cycling sprints in physically active young men.^[26]. A crossover study in male soldiers published in 2014 that used the same doses of caffeine and taurine also did not find improvements in physical performance.^[27] However, the dose of caffeine used in these studies was well below the threshold considered to be an erogenic dose (i.e., 3–6 mg per kg of body weight), and again, the dose of taurine was relatively low.

Based on the limited evidence available, it seems that low doses of taurine (i.e., about 1,000 mg) are unlikely to improve anaerobic exercise performance. Whether coingestion of caffeine and taurine improves anaerobic exercise performance more than either substance alone remains unclear, especially compared to caffeine alone, but in the case that it might, it appears a high dose of taurine (i.e., about 3,000–4,500 mg) is needed to do so.

With respect to cognitive outcomes, the summarized study reported improved reaction time in CAF+TAU compared to CAF, TAU, and PLA. This finding conflicts with previous evidence indicating that taurine does not have an independent effect on reaction time and that the effects of energy drinks on reaction time are primarily driven by their caffeine content.^[28][29] A notable difference between these studies is the type of test used to assess reaction time. Further randomized controlled trials are needed to tease out whether a combination of taurine and caffeine improve reaction time to a greater extent than caffeine alone.