Exercise is Medicine

by Jade Teta ND and Keoni Teta ND

Caffeine and Exercise

Caffeine is by the most popular exercise performance aid there is. Coffee and caffeine are often seen as the same, but the majority of studies on the performance-enhancing effects of caffeine come from isolated caffeine, not coffee. This month, we review some of the science behind caffeine’s use in sport and exercise.

The majority of studies show caffeine as a valuable aid in improving both endurance and sprint performance.^1–3 It also may have benefit in recovery from exercise and even play a role in speeding weight loss.^{1–3,12–13}

Caffeine Metabolism

After caffeine is ingested, it is metabolized into theophylline, theobromine, and paraxanthine. Since caffeine is lipid soluble, it can gain quick access to the brain and other tissues. It reaches circulation within 15 minutes of intake, and reaches full concentration in the blood after about 1 hour. Caffeine is cleared from the system in about 6 to 12 hours, depending on the individual metabolic rate.

One interesting aside regarding caffeine may be its varying impact on health depending on metabolic status. Those clearing caffeine quickly (so called fast metabolizers) may gain heart-protective effects from caffeine, while those who are slow metabolizers may have increased risk.^9–11 Coffee, not caffeine, is also the number one source of antioxidants in the American diet.^12,13

Caffeine Effects

Caffeine activates both the CNS and PNS. Studies suggest the stimulating action of caffeine on the nervous system may be the most important consideration when it comes to performance enhancement.^1–3 The major impact of this is enhanced mental focus and concentration, as well as improved motor function. Caffeine also results in increased B-endorphin concentrations, which may override the burning pain of intense activity. This same nervous system stimulation could also enhance sports requiring quick bursts of speed and intensity.

One very beneficial effect of caffeine is its impact on muscle glycogen. Caffeine spares glycogen and shifts the body toward a heavier reliance on fat from subcutaneous areas and fat within the muscle.^3,5 Efficiency of fat oxidation is a key component of endurance sports and exercise for fat loss. This is one reason why caffeine improves long-distance exercise performance. Caffeine may have even more benefit when consumed with carbohydrate. A 6% carbohydrate electrolyte beverage with added caffeine (5mg/kg) has been shown to elevate endurance performance by 9%.⁽⁾

Caffeine increases the catecholamine surge in response to intense exercise. Production of catecholamines is directly related to fat and glucose metabolism.^1–3 This, along with CNS activation, likely explains caffeine’s impact on high-intensity exercise performance. A 2006 study by Schneiker et al. looked at a 6mg/kg caffeine ingestion protocol in males compared to placebo.⁽⁾Caffeine or placebo was taken 60 minutes prior to two 36- inute exercise sessions involving repeated short sprints with 2 minutes’ rest between. Caffeine intake resulted in greater performance benefits and improved power. The performance benefit was shown in both the first and second sprint challenges (8.5% and 7.6% respectively versus placebo).

The same combination of carbohydrate with caffeine also enhances recovery from exercise. A carbohydrate recovery beverage with added caffeine, compared with the same beverage without caffeine, resulted in 66% greater glycogen synthesis⁾.⁷ Caffeine is able to improve glucose absorption, which may explain some of the findings.

Can It Help with Weight Loss?

Caffeine may help with weight loss, and/or coffee intake may have a role in weight loss.^12,13 If caffeine is having an effect on fat loss, this activity is likely a result of its impact on epinephrine release. Studies as far back as 1990 showed as little as 100 mg of caffeine, the equivalent in 1/3 cup of coffee, could increase thermogenesis in even habitual coffee drinkers⁾.⁸ Other studies on caffeine show increased fat oxidation as well. One older study published in 1979 showed a 30% greater blood free fatty acid level 2 hours post workout compared with placebo.^1–3,5

Dosing

Caffeine intake may not be the same as consuming coffee. The research on pure supplemental caffeine is fairly clear on performance benefits, but drinking coffee is far less established. Caffeine is best taken 15 to 60 minutes before exercise. The dose in studies is usually around 6 mg/kg bodyweight. That would mean that a 160-pound individual would be taking around 430 mg of caffeine. Since an 8 oz cup of strong coffee contains around 150 mg of caffeine, this equates to three cups of drip coffee.^1–3 A strong cup of coffee taken in a fasted state prior to exercise has benefited our clients clinically.

Final Thoughts

One of the major concerns regarding coffee has to do with dehydration and electrolyte loss. Recent information about coffee and risk of dehydration suggests that these concerns are unfounded. There is no good evidence to suggest that caffeine intake leads to an increased risk of dehydration.^1–3 Caffeine users can will develop tolerance, and occasional users enjoy slightly better benefits from coffee intake than chronic users. Coffee intake can also have a negative impact on digestive function, so there may need to be a period of acclimation for those unaccustomed to it.^1–3

Notes

1. Davis et al. Caffeine and anaerobic performance: ergogenic value and mechanisms of action. Sports Med. 2009;39(10):813–832.

2. Ganio et al. Effect of caffeine on sport-specific endurance performance; a systematic review. J Strength Cond Res. 2009;23(1):315–324.

3. Goldstein et al. International society of sports nutrition position stand: caffeine and performance. J Int Soc Sports Nutr. 2010;7:5

4. Schneiker et al. Effects of caffeine on prolonged intermittent-sprint ability in team-sport athletes. Med Sci Sports Exerc. 2006;38(3):578–585.

5. Ivy et al. Influence of caffeine and carbohydrate feedings on endurance performance. Med Sci Sports Exerc.1979;11:6–11.

6. Yeo et al. Caffeine increases exogenous carbohydrate oxidation during exercise. J Appl Physiol. 2005;99:844–850.

7. Pedersen et a. High rate of muscle glycogen resynthesis after exhaustive exercise when carbohydrate is coingested with caffeine. J Appl Physiol. 2008;105:7–13.

8. Astrup et al. Caffeine: A double-blind, placebo-controlled study of its thermogenic, metabolic, and cardiovascular effects in healthy volunteers. Am J Clin Nutr. 1990;51:759–767.

9. Cornelis et al. Coffee, caffeine, and coronary heart disease. Curr Opin Clin Nutr Metab Care. 2007;10:745–751.

10. Sachse et al. Functional Significance of a C–>A polymorphism in intron 1 of the cytochrome P450 CYP1A2 gene tested with caffeine. Br J Clin Pharmacol. 1999;47:445–449.

11. Djordjevic et al. Induction Of CYP1A2 by heavy coffee consumption is associated with the CYP1A2 -163C>A polymorphism. Eur J Clin Pharmacol. 2010; 66:697–703.

12. Bakuradze et al. Antioxidant-rich coffee reduces DNA damage, elevates glutathione status and contributes to weight control: results from an intervention study. Mol Nutr Food Res. 2011;55(5):793–797.

13. Kotyczka et al. Dark roast coffee is more effective than light roast coffee in reducing body weight, and in restoring red blood cell vitamin E and glutathione concentrations in healthy volunteers. Mol Nutr Food Res. 2011;55(10):1582–1586.