Posted by Jackson Peos in Sports Performance
Estimated reading time: 9mins
For years, caffeine has been used as an aid to enhance physical performance. Even though the body of literature supporting caffeine’s effects on physical and mental performance, recovery, and hydration is extensive, making sense of it can be challenging.
Let’s look at the evidence!
Over the years, multiple doses of caffeine have been proposed to be effective. For instance, A study by Graham and Spriet examined the exercise responses of well-trained endurance athletes to various doses of caffeine at 3, 6, and 9 mg/kg to evaluate the impact of it on exercise metabolism and endurance capacity. Subjects were instructed to take a caffeine capsule or a placebo before a bout of exercise (run to exhaustion at 85% VO2max). The authors reported that endurance was enhanced with both the 3 and 6 mg/kg dose of caffeine, whereas no significant effects were seen with additional consumption (9 mg/kg dose). Even though some studies have shown performance improvements with higher doses than 6 mg/kg, the evidence is fairly limited.
On the other hand, research on the effects of caffeine on strength performance is still in its infancy and the available data is mixed. An interesting study conducted by Woolf and colleagues instructed subjects to perform 2 exercises (chest press and leg press) to muscular failure separated by 60 seconds of rest and a Wingate test. Results showed an increase in performance during the chest press and the Wingate test after consuming a moderate dose of caffeine at 5 mg/kg.
A similar study by Beck et al. (2006), also studied the effects of caffeine supplementation on strength and muscular endurance. Subjects were tested for upper and lower body strength, as well as repetitions to exhaustion. Subjects were instructed to consume 201 mg (~2.1-3.0 mg/kg) of caffeine one hour before testing. Results showed significant performance increases in the upper body (but not the lower body) forstrength and endurance.
Consulting the literature as a whole, caffeine supplementation is likely to enhance high-intensity exercise (including team sports) when consumed in low to moderate doses (3-6 mg/kg) 1-hour before exercise. While less supported by the research, it is likely that weight training performance following consumption of caffeine in the range of 2-5 mg/kg will improve via improvements in strength, endurance, or both. Most studies show no additional benefits to consuming caffeine doses above 6mg/kg.
Bonus tip: Caffeine supplementation seems to be superior to consuming coffee (or other caffeinated beverages) for performance enhancement.
It has been proposed that caffeine supplementation may have stronger effects on areas other than metabolism and muscle. Although evidence of caffeine’s influence on mood and psychomotor performance is mixed at times, the overall research is promising.
Caffeine is believed to work as a stimulant benefiting motor and cognitive functions, particularly during mental and physical fatigue. For instance, Lieberman et al. (2002), studied the effects of moderate doses of caffeine on sleep deprivation and exposure to stress on cognitive performance. Subjects (Navy Seals) were assigned different doses of caffeine at random in either 100mg, 200mg, 300mg, or a placebo after 72 hours of sleep deprivation. The authors had subjects perform tests including vigilance, reaction time, working memory, and motor learning and memory. As expected, caffeine (200 to 300mg) significantly improved vigilance, reaction time, and alertness. Even though no significant advantage was seen from consuming 300mg (compared to 200mg), a 200mg dose was indeed superior to 100mg (no better than a placebo). Such findings suggest that 200mg of caffeine supplementation seems to be optimal in improving cognitive performance including learning and memory when exposed to stress and limited sleep.
Moreover, another study by Hogervorst and colleagues had trained cyclists (who were caffeine consumers) to perform a 150 minute 60% VO2 max trial followed by 5 minutes of rest and then a ride to exhaustion at 75% VO2 max, for 3 days. Subjects were told to consume either a commercially available food bar containing 100mg of caffeine, a non-caffeinated bar, or flavored water. Findings indicated that when the caffeinated food bar was taken, concentration was improved, as well as faster response speed and detection, and rapid visual test complex during both moderate-intensity cycling (60% VO2 max) and after time to exhaustion.
It is important to mention that such findings are of big importance for high-level sports performers since improvements in cognitive parameters like concentration, vigilance and alertness are essential in most sports. In conclusion, caffeine (or to a lesser extent caffeinated products), seems to significantly improve both physical and cognitive abilities during exercise and after exercise. The overall body of evidence suggests that a dose of 200mg of a caffeine supplement is appropriate for optimal improvements in cognitive parameters since higher doses don’t demonstrate additional improvements.
Caffeine (and caffeinated products) consumption has gained massive popularity over the last two decades. However, its potential to influence appetite and energy intake is still uncertain.
An interesting and thorough review by Schubert and colleagues aimed to answer the following 4 questions to clarify the role of caffeine and caffeinated beverages in energy regulation and appetite:
Results from this review showed that coffee consumption only marginally influences total daily energy intake (-55 calories) and does not significantly influence single meal energy intake or macronutrient distribution. Moreover, it was not suggested that caffeine alters gastric emptying, gut hormone secretion, or appetite perception in a way that would significantly influence energy intake.
Although there is some evidence for potential mechanisms by which coffee/caffeine can influence body weight (thermic effect of caffeine, gastrointestinal tract modification, & attenuation of diet-induced elevated hepatic insulin resistance) the authors came to the conclusion that currently there isn’t sufficient evidence to determine caffeine’s influence on appetite perception.
Research reviewing the effects of coffee/caffeine on energy intake is quite limited, and uncertain. Although caffeine appears to influence appetite alterations and energy intake, the limitations (dosage discrepancies, volume of caffeine content, and the number of studies) of the current data, make it difficult to isolate and discover a clear pattern or dose-response over short and long periods on energy intake and appetite regulation.