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active ingredients, caffeine is primarily responsible for Table 2 General Information About Using Caffeine to
the “energy rush” experienced. Several websites report- Enhance Performance
4
ing on caffeine levels found in food, drinks, and supple- • The usual dose recommended is 100mg up to 300mg, and
ments can be found on the Internet. 56 then only as needed.
• Monitor your own internal responses and performance
Energy drinks are increasingly becoming a public health changes when using caffeine to determine the optimal
issue because of how they are used. Several reports have dose for yourself.
associated consuming high volumes of energy drinks • The amount of caffeine in various products is only
with mania, seizures, and/or cardiac episodes that re- regulated for colas and other sodas, so often it is not
solved following cessation of the product’s ingestion. 58,59 possible to determine how much caffeine is contained in
In Canada, energy drinks are classified as a “food,” products such as dietary supplements and energy drinks.
but the caffeine content has been limited to 180mg per • Supplements, in particular proprietary blends, may
can or single-serving bottle (http://www.healthlinkbc.ca provide caffeine through cocoa beans, kola nuts, tea
/healthfiles/hfile109.stm). In Mexico, the sale of energy leaves, yerba maté, and/or guarana.
drinks to anyone under age 18 is prohibited, but in the • When using caffeine during periods of sleep restriction,
United States, no regulations are currently in place. 200mg may be taken every 3.25–3.5 hours to help sustain
However, a number of professional organizations have alertness (maximum: 800mg).
put forward guidance (http://www.beveragedaily.com • Although it is a myth that caffeine is a strong diuretic and
/Markets/Mexican-energy-drinks-regulations-could can contribute to dehydration, hydration status should
always be monitored.
-stunt-innovation-Euromonitor).
It is of interest that until 2004, the International Olympic based on the general recommendations that follow. Based
Committee considered caffeine a “controlled or restricted on the extant literature for caffeine and performance and
substance.” Now it is only part of the World Anti- the current regulations, up to 300mg/hr before exercise or
60
doping Agency (WADA) Monitoring program where an absolute dose of 200mg every 3 hours (not to exceed
substances, not included on the Prohibited List, are 400mg/day) during continuous operations may enhance
monitored to detect patterns of misuse in sports. Caf- performance. During periods of continuous sleep restric-
feine is monitored for “in-competition use” only. Previ- tion (less than 4 hours of sleep over several nights) up to
ously, athletes were allowed up to 12μg/mL caffeine in 800mg in 24 hours may be necessary to maintain per-
their urine prior to an event as this level was associated formance and is especially effective when combine with
26
with habitual use of caffeine in the diet of athletes even a 4-hour nap when possible. Additionally, the best en-
in large amounts. For example, if a 150lb person con- hancing effects of caffeine are seen in trained athletes, so
60
sumed around 300mg of caffeine in coffee and exercised you will not likely see returns unless you are in top physi-
for 1 hour or longer, (s)he would likely be below the al- cal shape. There is also some evidence to suggest that the
61
lowable limit, which suggests that surpassing that limit caffeine plays a role in the work-to-rest ratio, so follow-
would be proof of “doping.” 15 ing a specific training plan may be important.

Only a few of the studies on caffeine effects have been Disclaimer
conducted in combination with stress, other than sleep
deprivation. This limitation may have important impli- The opinions or assertions contained herein are the pri-
cations for SOF as they may consume vast amounts of vate views of the authors and are not be construed as of-
caffeine under conditions of chronic or extreme stress. ficial or as reflecting the views of the Army or Department
More research is needed to further examine the use of of Defense. Any citations of commercial organizations
caffeine under these conditions. and trade names in this report do not constitute an official
Department of the Army endorsement of approval or ap-
proval of the products or services of these organizations.
Conclusion
Table 2 illustrates various key points and recommen- Disclosures
dations and the following link provides downloadable
recommendations for use of caffeine (http://hprc-online The authors have no financial relationships or conflicts
.org/dietary-supplements/files/opss-caffeine-infographic to disclose.
/view). Importantly, recent studies have emphasized sev-
eral individual differences based on how caffeine affects References
bodily processes and how the body uses and breaks down 1. Fulgoni VL, Keast DR, Lieberman HR. Trends in intake and
caffeine. For this reason you should monitor your own sources of caffeine in the diets of US adults: 2001–2010. Am J
responses and performance changes when using caffeine Clin Nutr. 2015;101:1081–1087.

68 Journal of Special Operations Medicine Volume 16, Edition 4/Winter 2016