Caffeine and the strength athlete

Caffeine, as you probably know, is a central nervous system (CNS) stimulant.  It’s mode of action is similar to, but weaker than amphetamines.

There has been a lot of interest surrounding caffeine’s effects on sports performance with numerous studies showing its ability to enhance aerobic activity.  This is via a few different pathways, including enhanced fatty acid oxidation.  This means glycogen use is delayed which in turn delays fatigue.

With regards to the strength and power athlete, caffeines main effect seems to be on enhancing CNS function and hence motor unit recruitment.  This means that for any given muscle contraction there are more muscle fibres being recruited and this provides a stronger muscle contraction.  It has also been shown that caffeine increases the amount of calcium released into muscle cell, which is important for the speed of muscle contraction in response to nerve impulses.

In recent studies, caffeine ingested at a dose of 5-6mg/kg was shown to have significant effects on both strength and power output.  However, this effect was only seen in trained individuals.  Untrained subjects saw no improvement in maximal strength after ingesting 400mg of caffeine.  This seems to show that you need to have a decent amount of CNS activation anyway for caffeine to exert an effect.

As an extension of this, the use of energy drinks may be able to maintain maximal strength following an exhaustive bout of aerobic exercise.  Subjects performed 120 mins of interval cycling and were able to maintain their maximal strength on a resistance exercises compared to a placebo.  While not quite the same, this theory can be applied to multi-event sports carnivals or cross fit style competitions comprising multiple events in a day.

Again, there seems to be a classic dose-response curve with the optimal amount of caffeine being around 5-6mg/kg bodyweight.  It is interesting to note that below this (2.1-3 mg/kg), no significant effect was seen.

In case you’re wondering, with the current sporting climate in Australia especially, caffeine is not a banned substance,, at any dose, by ASADA or WADA.  The American NCAA have banned 15ug/ml dose in uranalysis however this equates to more than 9 cups of strong black coffee.  Unless you’re intent on giving yourself a heart attack, everyone should be fine keeping under the limit!

To sum up, caffeine helps strength and power athletes by increase CNS activation and allowing faster neuromuscular connectivity.  This allows you to recruit more motor units and hence contract the muscle faster and harder.  A dose of 5-6mg/kg should be all that is needed but bear in mind that doses of less than about 3mg/kg won’t provide any benefit.