New Research on Caffeine and Exercise Performance ☕
Hey y'all! This week, we are going to talk a little about some new research on our favorite drug: caffeine.
The performance-enhancing effects of caffeine for a broad range of physical activities have been well-established in numerous meta-analyses. A new review from researchers in Japan sheds a little more light on why exactly caffeine has this ergogenic impact. Importantly, this may also mean that caffeine could augment some of the health-promoting effects associated with physical activity as well.
But one dilemma associated with caffeine, that many people wonder about, is the potential for tolerance. Does using caffeine regularly make you habituated to its effects? Do you need to "save" it for the times when you really need it? A new meta-analysis might provide the answer. 👀
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This Week’s Research Highlights
☕ Caffeine may boost exercise performance, as well as enhance the health benefits associated with exercise, through improved secretion of myokines.
The most obvious impact of physical exercise is the improvement of the function and health of your muscles. But of course, we now know that the beneficial effects of exercise are manifold, extending to remote tissues far beyond skeletal muscle. This is due, in part, to myokines. Myokines are small proteins that are released by skeletal muscle cells in response to muscular contractions. They are secreted into the blood, where they can circulate throughout the body. We have myokine receptors in our liver, pancreas, bone, heart, and even brain cells, so they can bind to and influence virtually every organ system. For example, certain myokines are linked to improvements in insulin sensitivity, immune function, and even cognition. As I said, contracting your muscles triggers the secretion of myokines. But myokine production is also promoted by changes in intracellular calcium concentration. And this is where caffeine enters the picture. Caffeine has long been known to facilitate the release of calcium ions from the sarcoplasmic reticulum (this is a big part of how it enhances exercise performance). Furthermore, myokines are released after the activation of an enzyme called adenosine monophosphate-activated protein kinase, or AMPK for short. AMPK is often characterized as a sort of cellular fuel gauge and tends to get ramped up in states of energy stress. Caffeine is also an AMPK activator. In effect, the researchers are suggesting that caffeine is able to amplify some of the beneficial effects of exercise by acting on the same pathways. They then go into a few of the specific myokines that caffeine can act upon. Interleukin-6 (IL-6) is maybe the best-known of the myokines. It plays an anti-inflammatory role in the body by inhibiting tumor necrosis factor-α (TNF-alpha), and it improves glucose tolerance. Caffeine supplementation has been shown to induce higher IL-6 levels in response to running. Preliminary research also suggests that caffeine could increase the secretion of brain-derived neurotrophic factor (BDNF), a myokine that plays a role in learning and memory. And muscle, a myokine that is linked to mitochondrial biogenesis and endurance adaptations, is responsive to changes in calcium concentrations, and caffeine administration could increase its expression. Taken together, this suggests that caffeine could function as an exercise mimetic. Not only does this make it a useful adjunct for athletes, it could also help boost levels of myokines, as well as lactate, in people who aren't able to engage in prolonged high-intensity exercise.
☕ Habitual caffeine consumption does not dampen the potential of caffeine as an ergogenic aid.
Researchers affiliated with the University of São Paulo in Brazil performed a systematic review of the literature investigating caffeine consumption and exercise performance. Importantly, they only included studies that provided information on habitual caffeine intake in the participants, meaning whether or not (and to what extent) they consumed caffeine on a regular basis. After this screening process, they conducted a meta-analysis of 60 randomized controlled trials, enrolling a total of 1,137 participants, which looked at the influence of habitual caffeine intake on exercise performance in various domains and populations. The researchers determined, to no surprise, that caffeine overall had a positive effect on performance when compared to a placebo. Benefits were universal to all forms of caffeine, including both pills and natural sources like coffee. Furthermore, both men and women benefited, as well as trained and untrained individuals, and all forms of exercise (endurance, power, strength) showed improvements, although longer-duration aerobic activity seems to benefit most strongly. Most importantly, no influence of relative habitual caffeine consumption was demonstrated. In other words, being a regular coffee drinker did not mean that participants got less of a performance payoff when they were given caffeine experimentally. When the researchers compared doses, they did find something slightly interesting — the ergogenic effects of caffeine were only shown when the caffeine dose was less than 6 mg per kg of body mass. With higher doses, (we're talking more than 500 mg of caffeine) the improvements in performance diminished and were no longer statistically significant. (My guess is that the unpleasant side effects of too much caffeine wind up overriding the performance-enhancing impact of the drug.) Obviously, this study is encouraging for those of us who are regular coffee drinkers and don't want to rein in our consumption. But it's also good news because the health-promoting effects of caffeine-containing beverages, like coffee and green tea, are generally only realized through regular use. Much as the title of this paper suggests, you really can have your coffee and drink it too.
Random Trivia & Weird News
🐝 Caffeine may make bumble bees more productive.
Many humans rely on caffeine daily for its stimulant effects. Believe it or not, some bugs may respond to caffeine in a somewhat similar way.
A team of researchers fed bumble bees caffeinated food alongside a floral odor blend. Then, in a lab setting, the bees were presented with a bunch of robotic flowers, some of which emitted the same aforementioned floral odor and some emitting different smells. The bees that had been primed with caffeine gravitated more to the target flowers, versus control bees or those that had only been primed with the odor but no caffeine. Caffeinated bees also made greater improvements in their floral handling, suggesting that caffeine was enhancing motor learning.
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The researchers believe that this caffeine method could be used to boost fruit yields by biasing pollinators toward specific crops.
Lead author Sarah Arnold, in a press release, said, “We generally know how coffee helps us concentrate and stay focused, as well as helping us remember complex information better, and what our limit is. We’ve shown that caffeine increases the bees’ enthusiasm and activity generally and it makes the memory formation stronger."
Podcasts We Loved This Week
- José González-Alonso: Exercise in the heat, dehydration, fluid ingestion, and circulation. Via Inside Exercise.
- • Michael Elowitz: Can we program our cells? Via The Joy of Why.
Products We Are Enjoying
Matcha
Matcha is a powder made from finely ground green tea leaves. Because you are consuming the whole plant, as opposed to an infusion like when you use tea bags, you wind up getting far more of the bioactive catechins, like EGCG. I favor this brand in particular because it has been third-party lab-tested for quality, safety, and polyphenol content. It also, of course, contains a modest amount of caffeine (around 32 mg of caffeine for a 2-gram serving).
