Published on Enhanced Fitness and Performance (http://enhancedfp.com)

Caffeine And Performance- Official ACSM Statement

By DMorgan
Created 09/10/2013 - 1:27pm
Caffeine and Exercise Performance
Caffeine may be the most widely used stimulant in the world. It is found in a variety of
plants, dietary sources (including coffee, tea, chocolate, cocoa, and colas), and non-
prescription medications. The average caffeine consumption in the USA is approximately 2
cups of coffee per day (200 mg); 10% of the
population ingests more than 1000 mg per day.
Caffeine is a socially acceptable, legal
drug consumed by all groups in society.
Caffeine is often referred to as a nutritional
ergogenic aid, but it has no nutritional value.
Ingested caffeine is quickly absorbed from the
stomach and peaks in the blood in 1-2 hours.
Caffeine has the potential to affect all systems of
the body, as it is absorbed by most tissue.
The remaining caffeine is broken down in the liver and byproducts are excreted in urine.
Laboratory studies from the 1970’s suggested that caffeine enhanced endurance
performance by increasing the release of adrenal
ine into the blood stimulating the release of
free fatty acids from fat tissue and/or skeletal
muscle. The working muscles use this extra fat
early in exercise, reducing the need to use mu
scle carbohydrate (glycogen). The “sparing”
of muscle glycogen made more available later in exercise to delay fatigue.
In the 1980’s, many studies found that caffe
ine did not alter exercise metabolism, and
implied that it had no ergogenic effect, wit
hout actually measuring performance. A few
reports did examine caffeine and performance
during endurance exercise and generally
found no ergogenic effect. By the end of the decad
e, it was suggested that caffeine did not
alter metabolism during endurance exercise and may not be ergogenic.
Recent work reported that ingestion of 3-9 mg
of caffeine per kilogram (kg) of body weight
one hour prior to exercise increased endurance running and cycling performance in the
laboratory. To put this into perspective, 3
mg per kg body weight equals approximately one
mug or 2 regular size cups of drip-percola
ted coffee; and 9 mg/kg = approximately 3 mugs
of 5-6 regular size cups of coffee. These st
udies employed well-trained, elite or serious,
recreational athletes. Studies with untrained individuals cannot be performed due to their
inability to reliably exercise to exhaustion.
The mechanism to explain these endurance improvements is unclear. Muscle glycogen is
spared early during submaximal exercise following caffeine ingestion (5-9 mg/kg). It is
unknown whether glycogen sparing occurs as a result of caffe
ine’s ability to increase fat
availability for skeletal muscle use. Furthe
rmore, there is no evidence supporting a
metabolic component for enhancing performance at a low caffeine dose (3 mg/kg).
Therefore, it appears that alterations in mu
scle metabolism alone cannot fully explain the
ergogenic effect of caffeine during endurance exercise.
Research suggests that caffeine ingestion impr
oves performance during short-term exercise
lasting approximately 5 minutes at 90 to
100 percent of maximal oxygen uptake in the
laboratory. This exercise intensity requires ma
ximal provision of energy from both aerobic
(oxygen requiring) and anaerobic (non-oxygen) source
s. It is unknown if this finding applies
to race situations. The reasons for the perf
ormance improvement may be a direct positive
effect of caffeine on muscle anaerobic energy provision and contraction or a central nervous
component related to the sensation of effort.
Caffeine ingestion does not appear to improve
sprint performance, but additional well-controlled
laboratory and field studies are required to
confirm this conclusion. Sprinting is defined as
exercise that can be maintained from a few
seconds to 90 seconds where most of the required energy is derived from anaerobic

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