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Study under review: Caffeine Supplementation: Ergogenic in Both High and Low Caffeine Responders
Competitive athletes frequently explore the use of performance enhancing (i.e. ergogenic) agents to give them that extra edge. According to the National Institutes of Health, international surveys revealed that 66% of nearly 4000 surveyed adult and adolescent elite track and field athletes reported using one or more ergogenic supplements. Even amateur individuals in the general population who are simply looking to maximize their workout time will often consider using products like “preworkout” supplements, sports and energy drinks, protein and amino acid supplements, and other agents.
Many of these products contain caffeine, a central nervous system stimulant that can be found in varying amounts in a number of natural plant sources. Almost 90% of the general population consumes caffeine on a regular basis, with the most common sources being coffee, soft drinks, and tea. Improvements in mental alertness, concentration, fatigue, and athletic performance are well-established benefits of caffeine consumption up to 400 milligrams per day.
Caffeine ingestion has been touted to boost energy and minimize fatigue during athletic activity, and a number of studies have indeed observed increased aerobic, anaerobic, and neuromuscular performance after consumption. While it is widely accepted that caffeine blocks adenosine receptors in the brain, thereby producing a more awake and alert state, other mechanisms of its activity are less understood. Some studies have shown that caffeine exerts endurance-promoting metabolic changes by inducing higher adrenaline output, leading to more fatty acids being burned for fuel while sparing glycogen stores. Caffeine may also have local effects on the muscular system by mobilizing calcium and increasing muscle contractile force. Furthermore, caffeine may improve endurance by boosting nitric oxide levels and enhancing blood vessel dilation, which both permit increased oxygen- and nutrient-rich blood flow into muscles.
However, not all studies have shown these types of effects on athletic performance and not all studies have agreed on the precise mechanism by which caffeine may produce these changes in performance. Researchers have suggested that interindividual differences in biological response to caffeine may influence its effects on athletic performance. In an effort to remove this barrier, this study crafted a research design in which participants were grouped as either “high” or “low” caffeine responders using multiple measures.
Caffeine is touted as a performance-enhancing agent, but some people physiologically respond differently to it, which may explain its ergogenic variability. This study explores this hypothesis by splitting athletes into two groups, low responders and high responders, and putting them through a rigorous endurance challenge.
Other Articles in Issue #52 (February 2019)
Carnivores convert carnitine, but can vegetarians?
Trimethylamine N-oxide (TMAO) is associated with an increased disease risk. It's manufactured with the help of the gut microbiome from L-carnitine. Vegetarians make less TMAO from L-carnitine than omnivores do. The question is: why?
Can lemon balm help manage type 2 diabetes mellitus?
Lemon balm is a plant that may have antidiabetic and cardiovascular effects. This study explored how it impacts glycemic control and cardiovascular risk factors in people with type 2 diabetes.
Do low carbohydrate diets increase cardiovascular risk?
This meta-analysis found that low carb diets bump up LDL-C levels slightly. What's less clear is how much this matters.
Interview: Jason M. Valadão, MD, MA, MLS, Lieutenant Commander, US Navy
We chat with physician, naval officer, and author Jason Valadão about the nutritional strategies he uses with his patients, his top tip for gaining control of exercise and diet routines, and more.
Does a post-workout high GI meal improve sleep and next day training performance?
This study aimed to explore how a high glycemic index meal after an evening training bout affects both sleep and performance.
The anti-inflammatory effect of a vegan versus American Heart Association-recommended diet in coronary artery disease
Inflammation plays a major role in cardiovascular disease. This study examined whether a vegan or AHA-recommended diet can make a bigger impact on a major inflammatory marker in people with coronary artery disease.
Interview: Shavawn M. Forester PhD, RDN
In this chat with the Chief Science Officer of The Nutrient Institute, we discuss science communication, her take on some popular nutrition topics, and more.