Caffeine for Athletic Performance: Sources, Doses, Timing and Expected Effects

By: Lawrence L. Spriet, Ph.D.

Introduction and Background

Caffeine is the world’s most consumed drug. It has a role in many social activities and improves quality of life by helping individuals feel better, have more energy and complete work tasks more effectively (Burke et al., 2013).

Caffeine is also popular with athletes, and there are many reports of caffeine’s ergogenic or “work enhancing” effects in sport settings (Desbrow and Leveritt, 2007). While popular, the science supporting caffeine in sport is only a few decades old. Pioneering work determined that caffeine at doses of 6-9 mg/kg/body mass (BM), or ~3-4 cups of coffee, was effective at prolonging endurance in activities like cycling and running (Graham and Spriet, 1995; Spriet, 2014). In those days, caffeine was a “restricted substance” according to the International Olympic Committee (IOC). Athletes could consume caffeine, but only a minimal amount was allowed. In 2004, the IOC and the World Anti-Doping Authority (WADA) removed caffeine from the restricted substance list, primarily because it was shown to be highly ergogenic even at low doses; the short- and long-term side effects were minimal; and the drug was socially acceptable world-wide (Burke et al., 2013).

Caffeine is derived from plants and is both water and fat soluble. The liver metabolizes caffeine slowly (half-life of 3.5 – 5 hr), which allows its effects to last a long time. There is a large variation between people in the response to caffeine (Yang et al., 2010).

Because the chemical structure of caffeine is very similar to the neurotransmitter, adenosine, it exerts its main effects relating to sports performance by antagonizing the effects of adenosine in the central nervous system (CNS). Adenosine’s primary role in the brain is to slow things down, but caffeine crosses the blood brain barrier, reverses these effects and acts as a CNS stimulant to increase alertness, vigilance, arousal, wakefulness, cognition and improve mood (Spriet, 2014).

Caffeine also interferes with feedback from the muscles and other organs to the brain and reduces pain perception, force sensation and ratings of perceived exertion during exercise (Astorino et al., 2011; Doherty and Smith, 2005). These effects add up to an improved ability to perform in sports. The effects are especially strong when the athlete is already tired from prolonged activity (Cox et al., 2003; Talanian et al., 2016).

Research Supporting the Athletic Performance Benefits of Caffeine

Most experimental work examining the potential for caffeine to improve athletic performance has been done in laboratory settings with tightly controlled trials.

A recent study examined whether low doses of caffeine consumed late into exercise improved cycling time trial (TT) performance. Eighty minutes into a 120 min ride, 15 cyclists drank either a sports drink, a sports drink with 100 mg caffeine or a sports drink with 200 mg caffeine. Results showed those who drank 200 mg caffeine completed a subsequent time trial 1 minute faster than their baseline.  (Talanian and Spriet, 2016).

Additional research has now examined the effects of caffeine on repeated sprinting tasks (Astorino et al. 2010), reactive agility tests (Duvnjak-Zaknich et al. 2011) and sport situations including tennis, soccer, rugby, volleyball, basketball and field hockey (Del Coso et al., 2016; Perez-Lopez et al., 2015; Spriet 2014). These studies have provided evidence that caffeine improves physical performance and skill execution in stop-and-go sports.

For example, a recent study with 15 male adolescent basketball players had athletes consume either 3 mg caffeine/kg BM or no caffeine before performing free throw and 3-point shooting, a maximal countermovement jump (CMJ), repeated maximal jumps for 15 s and a Yo-Yo intermittent recovery test (Abian-Vicen et al., 2014). Shooting and the Yo-Yo test were not affected by caffeine, but jump height in the CMJ and cumulative jump height in the 15 s test were improved by caffeine. A second study had 15 male collegiate basketball players ingest either a placebo or 6 mg caffeine/kg 1 hour before completing a 3 min all-out exercise task. The athletes had significantly higher power outputs and a lower fatigue rate during the test following ingestion of caffeine compared to the placebo (Cheng et al. 2016).

Additional research has demonstrated that the ergogenic effects of caffeine are robust and independent of gender, habitual use and withdrawal of caffeine, mild dehydration, consuming a high carbohydrate diet, intake of carbohydrate during exercise, co-consumption of caffeine with creatine or sodium bicarbonate (Spriet, 2014).

Recommended Practical Applications of Caffeine Use

• Low doses of caffeine (1.5 – 3 mg/kg BM) improve sports performance in most athletes
• ~200 mg of caffeine may be the optimal dose for performance enhancement in most people
• Caffeine can be taken in the hour before exercise, during exercise or in the latter half of prolonged exercise to improve performance
• Encourage athletes to trial the use of caffeine in practice before using it in competitive settings.
• Caffeine side effects are minimal or non-existent with doses of ~3 mg/kg BM or ~200 mg
• At moderate to high doses (6 – 9 mg/kg BM), athletes may experience anxiety, jitters, insomnia, inability to focus, gastrointestinal unrest, irritability, blabbermouth syndrome, etc.
• There is the risk of dependency with chronic caffeine use (anxiety and sleep disorders) and withdrawal effects may occur

Reference List

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