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Caffeine improves morning exercise performance

Posted on Friday, 20 April, 2012 by anthony

Any strength or endurance athlete who has trained in the early morning or late at night will be well aware that their exercise performance is often reduced compared with afternoon and evening training. This process by which sporting performance is affected by the time of day is governed by our circadian rhythm - often referred to as our body clock - and has been shown to measurably reduce morning exercise performance in both strength/power events and endurance events. The exact reasons for the decline in exercise performance are not completely clear, however, it is generally believed that variations in hormones, body temperature, heart rate and blood pressure appear to play a role. Recent research has found that the consumption of caffeine (3mg/kg bodyweight) reversed the morning reductions in maximum dynamic strength and muscle power output, increasing muscle performance in highly-resistance trained men to the levels found when training in the afternoon (Mora-Rodriguez et al., 2012).

About the Caffeine Research

The researchers recruited twelve highly resistance-trained men (age 19.7±2.8 yr, body mass 74.6±2.3 kg, body fat 11.6±0.8%, resistance training experience 7.2±2.4 yr) to take part in the experiment - a randomized, double-blind, crossover, placebo controlled experimental design with all subjects serving as their own controls. Each subject underwent three testing conditions: 1) Morning testing with caffeine (10:00AM); 2) Morning testing with placebo (10:00AM); 3) Afternoon testing with placebo (18:00). The caffeine and placebo capsules were ingested 60 minutes before testing. Subjects refrained from physical activity as well as alcohol, tobacco and caffeine for 4 days before testing.

During the experiment the researchers measured a number of measures of strength and power including: 1) Velocity for maximum power load; Velocity for maximum strength loads (i.e., load of 75% 1RM); 2) Maximal isometric voluntary contraction on the right knee(MVCLEG); 3) Maximal isometric contraction of the right hand (MVCARM); 4) Electrically evoked maximal isometric contraction (EVOKLEG) of the right knee extensors; 5) subjects also completed 1 set of 6 free-weight full squat repetitions at 85% of 1 RM and blood samples were taken to measure the plasma epinephrine (E) and norepinephrine (NE) concentration – this was used as an index of whole body sympathetic nerve activation. Blood hematocrit and hormone levels (i.e., serum testosterone, cortisol, growth hormone, and plasma nor-and-epinephrine) were evaluated at the beginning of each trial (PRE) and catecholamines at the end of the maximal sympathetic stimulation bout of exercise (POST).

What effect did caffeine have on morning exercise performance?

Effect of caffeine on strength and power

  • Caffeine ingestion increased the squat and bench press muscle power output by 2.5-5.7% compared with the AM placebo. There was no significant difference between AM caffeine or PM placebo indicating that caffeine restored morning muscle power output to afternoon levels.
  • The velocity for maximum strength loads (load of 75% 1RM) was significantly greater in the AM caffeine than in the AM placebo group, for both the squat and bench press (5.3% and 4.6% improvement respectively). There was no significant difference between the AM caffeine or PM placebo group indicating that caffeine restored muscle strength to afternoon levels.
  • The electrically evoked right leg muscle strength test was significantly higher in the AM caffeine compared with the AM placebo (16%)
  • The concentration of plasma norepinephrine increased 5x after the AM Caffeine trial and was significant higher than in the AM placebo trial
  • Caffeine had a significant effect on dynamic muscular contractions but not on isometric contractions

What does the research tell us about the use of caffeine during morning workouts?

The researchers suggest that not only does their research support the use of caffeine as an ergogenic aid but also suggests that caffeine ingestion prior to a morning workout actually restores neuromuscular performance (strength and power output) to the levels produced in an afternoon training session. They found that caffeine ingestion increased squat and bench press power output by 2.5-5.7% and improved the velocity for maximum strength loads by 5.3% and 4.6% in the squat and bench press. The researchers observed that neuromuscular performance - maximum dynamic strength and muscle power output - improved in the range of 3–6% and stated that the observed strength and power enhancements following caffeine (3mg/kg-1 – equivalent to 2.5 espresso coffees for a 75 kg athlete) “have the potential to prevent the morning declines in sport performance, allowing athletes to train and compete at the level of the evening”

The researchers concluded that caffeine reverses the morning reductions in maximum dynamic strength and muscle power output (2.5-7.0%), increased muscle performance to the levels found in an afternoon training session and “avoids the morning reduction in muscle performance due to circadian rhythm”.

In summary:

  • 3mg/kg-1 – equivalent to 2.5 espresso coffees in a 75kg athlete – improved dynamic muscle strength and power output compared with a placebo
  • Caffeine increased performance levels to those seen in an afternoon session reversing the normal circadian rhythm
  • Caffeine improved both upper body and lower body performance
  • Caffeine improved dynamic muscular contractions but not isometric muscular contractions

References:

Mora-Rodríguez R, Pallarés JG, López-Samanes Á, Ortega JF, Fernández-Elías VE (2012) Caffeine Ingestion Reverses the Circadian Rhythm Effects on Neuromuscular Performance in Highly Resistance-Trained Men. PLoS ONE 7(4): e33807. doi:10.1371/journal.pone.0033807

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