Caffeine for Endurance

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Caffeine is a legal CNS stimulant that has been proven in numerous research articles to significantly improve endurance exercise performance. It is one of the most researched endurance sports supplements and is one of only a handful of supplements recognised as having a true ergogenic effect on exercise and endurance performance. This has led to the IOC setting an upper limit for caffeine consumption, which is currently set at 12 ug,ml−1 of caffeine in urine.

How does caffeine improve endurance exercise performance?

The exact mechanisms by which caffeine improves endurance performance is not completely clear. Caffeine is believed to have an ergogenic effect through a number of possible mechanisms including: 1) increased CNS (central nervous system) activation; 2) improved muscle force/power production; 3) Reduced rate of perceived exertion (increased pain tolerance); 4) increased secretion of the stress hormone catecholamine which may increase blood free fatty acid levels, and; 5) Increased rates of fat metabolism which may help to preserve valuable muscle glycogen stores.

Current research supports the idea that caffeine’s main ergogenic effect is through a combination of increased muscle contractile force production and enhanced CNS activation/arousal which may reduce the rate of perceived, increase pain tolerance by blunting pain levels (Laurence et al., 2012; Tarnopolsky 2008).

Caffeine and endurance cycling performance

Caffeine has been shown to significantly improve cycling performance, particularly time trial performance. When taken at a dose of 5mg/kg it has been shown to increase work rate, heart rate, oxygen uptake and energy expenditure during a 30minute cycling time trial in a group of sedentary men (Laurence et al., 2012). Interestingly, the improved time trial performance occurred without changes in ratings of perceived exertion or the respiratory exchange ratio. Researchers have also shown that 10km cycling time trial performance was improved by caffeine administration (5mg/kg) in both endurance trained and active men (Astorino et al., 2012). Similar results have also been observed during a longer (60 minute) cycle at 75% of peak sustainable power using caffeine doses of 3mg and 6mg/kg (Desbrow et al., 2012). The researchers concluded that doubling the caffeine dose to 6mg/kg did not offer any further performance benefit over 3mg/kg. Recent research has found that consuming caffeine as coffee appears to be equally as effective at improving cycling time trial performance as caffeine anhydrous tablets (Hodgson et al., 2013).

Caffeine and endurance running performance

Similar results have been observed during running time trials (Marangon and Mendes 2011; Bridge and Jones 2006; Wiles et al.,1992). In one running study the consumption of 3mg/kg of caffeine before an 8km time trial was found to significantly improve 8km running performance by ~24 seconds (Bridge and Jones 2006). Research looking at the effect of 5mg/kg of caffeine anhydrous on 5,000m time trial also observed significant improvements in time trial performance with an average improvement of 51 seconds following caffeine consumption (Marangon and Mendes 2011). Interestingly the caffeine supplement improved performance without having a significant effect on either Blood lactate or glucose levels. Caffeine has also been shown to improve running performance over shorter distances with ~4seconds improvement over 1500m (Wiles et al.,1992).

Does caffeine withdrawal further improve the beneficial effects of caffeine on endurance performance?

Interestingly when researchers looked at the whether caffeine withdrawal (for four days) enhanced the effect of caffeine administration (3mg/kg) on exercise performance they found that there was no benefit gained from caffeine withdrawal (Irwin et al., 2011). Therefore there appears to be no need to reduce caffeine consumption prior to competition in order to maximize the beneficial effects of caffeine.

Is caffeine beneficial for endurance in hot conditions?

It is often suggested that caffeine may negatively affect hydration levels during exercise, due to its mild diuretic effect. As such some people have questioned whether caffeine is beneficial when exercising in hot conditions. However, researchers have found that caffeine (3mg/kg and 6mg/kg) appears to have an ergogenic effect whilst cycling in both hot and cold conditions (Ganio et al., 2011 & 2011a; R). Of interest was that caffeine reduced leg pain whilst exercising in hot conditions (Ganio et al., 2011). Similar improvements in endurance performance following caffeine administration (5mg/kg) have been observed in runners exercising in hot conditions (Ping et al., 2010). Chronic caffeine administration (3 and 6mg/kg) was also found to have no negative effect on fluid levels or thermoregulation during an exercise heat tolerance test (Roti et al., 2006).

What’s the best form of caffeine to take?

Research looking at caffeine and endurance exercise performance, have normally used caffeine supplements (e.g. caffeine anhydrous tablets) which has been generally been considered to be more effective than consuming caffeine through coffee. Caffeine anhydrous is the form of caffeine that is present in caffeine tablets such as Pro-plus tablets. However, recent research has found that consuming caffeine in coffee appears to be equally effective for improving endurance exercise performance (Hodgson et al., 2013).

How much caffeine do you need to take for endurance benefits?

Current research suggests that you should consume 3-6mg of caffeine anhydrous per kg of bodyweight. Some research has found that there is no further benefit of consuming 6mg/kg over 3mg/kg. You may benefit from experimenting with different doses prior to an important event.

What’s the IOC legal caffeine limit?

The IOC legal caffeine limit is 12 ug,ml−1 of caffeine in urine – the quantity of caffeine required to reach this level will vary from person to person and is strongly influenced by bodyweight. For most people consuming 9mg/kg of caffeine (equivalent to 630mg for someone weighing 70kg) could increase caffeine level that approaches the current IOC limit. Most research suggests that endurance athletes can maximize performance by consuming 3-6mg/kg (210mg – 420mg) of caffeine which is within the legal range. It’s also worth noting that 3mg/kg of caffeine appears to be equally effective as 6mg/kg and is well within the legal limit.

Will every endurance athlete benefit from caffeine?

As with other sports supplements there will be a percentage of people who do not benefit, or benefit as much from caffeine consumption. Some people have increased sensitivity to caffeine and may not get the same benefit from caffeine consumption or may need to reduce the caffeine dose further. For this reason you may wish to test whether caffeine is of benefit to you before using it in an important race.

Caffeine and endurance exercise performance summary:

  • Caffeine has been shown to significantly improve endurance exercise performance in a range of endurance sports such as cycling and running.
  • It is considered one of the most effective endurance supplements
  • It is believed to have this effect mainly through increased stimulation of the CNS, muscle contractile force production, and blunting pain levels.
  • Caffeine appears to exert optimum benefits when consumed at 3-6mg/kg bodyweight – however consuming 6mg/kg does not appear to provide further performance benefits over 3mg/kg.
  • Caffeine anhydrous is considered to be the best form of caffeine although recent research suggests that consuming caffeine from coffee may be equally effective
  • Consuming 9mg/kg could result in a caffeine level that is close to the IOC limit – 3-6mg/kg is within the legal level.
  • Not all athletes benefit from caffeine and therefore may wish to experiment in a less important race or time trial before using in an important event.
Caffeine and Endurance Exercise Performance References:

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