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caffeine and exercise

Caffeine and its Effects on Exercise

Caffeine is one of the most important natural products. It has become a big part of our lives, so much so that virtually everyone relies on a hot cup of coffee to get the day going or get through a long night. It’s also a major ingredient in many carbonated beverages like coke, energy drinks and even drugs for various ailments.

Caffeine has various benefits, but it also has its downsides. The question is, are you aware of these benefits? Do you know how much caffeine is safe enough? And do you know how caffeine can help your workout and bodybuilding routines? If the answers to these are No, then you’re in the right place. If the answers are yes, stick around still – there’s a lot of new stuff you could learn.


what is caffeine

What is caffeine?

Caffeine is a naturally occurring chemical commonly found in the coffee plant (Coffea arabica), tea plant (Camellia sinensis), cocoa (Theobroma cacao), cola and several other plants. Caffeine is also found in several consumer products, like chocolate sweets and energy drinks.

Caffeine has stimulant effects on the CNS, making it widely used to improve alertness and “fight sleep.” It also affects several other organs in the body and is used to treat ailments like asthma and obesity.

Caffeine is often regarded as a two-edged drug, having many beneficial effects but also packing several side effects. As a result, the U.S. prohibits the bulk sale of caffeine to consumers. As a stimulant drug, caffeine also finds use as a performance enhancer amongst athletes. While performance enhancers are generally frowned upon in sports, caffeine use is permitted within regulatory limits.

How Caffeine Works

Caffeine is rapidly absorbed and transported to the liver when consumed. In the liver, caffeine is broken down into active metabolites which travel to various organs, primarily the brain.

Caffeine acts via different mechanisms at its various sites of action. These include;

  • Antagonism of adenosine receptors
  • Inhibition of phosphodiesterase enzymes (PDE)
  • Antagonism of benzodiazepine receptors
  • Release of intracellular calcium

The net effect of these mechanisms is to stimulate neural excitation. In addition, caffeine may also stimulate adrenaline, norepinephrine and dopamine release, thus, increasing mental alertness and promoting focus.

Caffeine exerts its effects quickly, taking about an hour to reach maximum blood levels. Caffeine’s effects on the brain make it classed as a psychoactive drug.

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Effects of Caffeine

Caffeine affects numerous systems in the body, causing several effects, some beneficial and others not so much.


Beneficial Effects

Some beneficial effects of caffeine include;

  • Improving memory and cognition
  • Improving mental alertness and reducing fatigue
  • Reduces risk of Alzheimer’s and Parkinson’s
  • Reduces suicide risk
  • Reduces intracranial pressure, thus relieving headaches and migraines
  • Stimulates diuresis (removal of excess fluids)
  • Stimulates bronchodilation, thus helping asthmatics breathe better
  • Aids fat-burning and weight loss
  • Reduces the risk of certain cancers like liver cancers
  • Improves muscle strength and enhances exercise performance
  • Helps prevent liver and colon cancer
  • Improves peripheral blood flow, helping to enhance blood delivery to muscles and major organs.
  • Reduces the risk of gout
Negative Effects of Caffeine

Negative Effects

Caffeine has some negative effects, which typically occur with overdose. Sometimes, however, these negative effects may occur at normal doses. Acute overdose or prolonged use of caffeine may;

  • Increase heart rate and blood pressure. While this effect is transient, caffeine may worsen hypertension and arrhythmias.
  • Cause insomnia. Studies show that caffeine intake within normal limits may disrupt total sleep time, causing tiredness. This creates a negative cycle where a person becomes caffeine dependent.
  • Induce type 2 diabetes
  • Adversely affect pregnancies, leading to termination or delayed fetal growth.
  • Adversely affects female fertility
  • Induce stomach ulcers
  • Trigger gout in persons that already have the condition.
  • Cause urinary incontinence
  • Induce headaches and migraines caused by dilation of intracranial blood vessels after pausing caffeine.
  • Deplete serotonin levels over time, thereby causing or worsening symptoms of depression and anxiety
  • Deplete calcium stores, thereby causing osteoporosis
  • Disrupt neural signaling to muscles, thereby causing muscle spasms and tremors

Caffeine is quite addictive, and the American Psychiatric Association recognizes caffeine withdrawal as a mental condition. Caffeine addicts may experience several withdrawal symptoms after 24-48 hours of caffeine avoidance. These include; headache, fatigue, low energy, irritability, anxiety, poor concentration, depressed mood and tremors, lasting up to 9 days.

An overdose can result in death due to convulsions.


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Recommended Caffeine Intake

To avoid its negative effects, caffeine is recommended to be taken within specified daily limits. Caffeine is regarded as food and a drug. As such, it should be taken moderately.

The average American takes about 135mg of caffeine daily. Per the U.S. FDA, 400 mg (equivalent to 4 cups of brewed coffee) daily is the safe limit for caffeine intake for adults. However, children between 12 and 18 should not consume more than 100mg daily, while 200mg is considered a safe limit for pregnant women. Children below 12 years should not take caffeine at all.

Because of its habit-forming effect, caffeine should not be taken regularly. Doses of up to 10g are considered lethal.


Sources of Caffeine

Caffeine may be obtained from various natural and artificial sources. As an alkaloid, caffeine is naturally found in varying proportions in various plants. It is also added to various beverages and medications.


Natural caffeine sources

Caffeine occurs naturally in over 60 plant species. Plant parts or extracts from these plants are often sold for caffeine content.

The table below gives the concentration of caffeine from natural sources.

[table id=31 /]

Alternative caffeine sources

Caffeine is a major ingredient in several beverages, sweets, energy drinks and even over-the-counter medication. The caffeine added to these products is commonly synthetic. Synthetic caffeine costs less to produce than extracting caffeine from plant sources,

The table below gives the average caffeine content in various non-natural sources.

[table id=32 /]



Guarana (Paullinia cupana) is a plant native to South America, similar to the coffee plant, and is a rich source of caffeine. Guarana is largely used as an ingredient in energy drinks and soft drinks. Guarana extract powder is also sold as a supplement to boost energy levels and mental alertness. 

Guarana contains several antioxidants and other phytoconstituents that make it medicinally beneficial. Taking guarana may help improve cognition, induce weight loss, relieve diarrhea and promote heart health.

Common sources of guarana include;

  • Energy drinks like RedBull and Monster
  • Guarana powders
  • Guarana supplements
  • Guarana plant
Guarana vs. Caffeine

Guarana vs. Caffeine

Guarana shares many similarities with caffeine, but there is some marked difference between both substances.

First, guarana has a greater stimulating effect compared to caffeine. Caffeine is a single stimulating substance, whereas guarana seeds or powder extracts contain caffeine with other stimulants like theophylline and theobromine. Guarana’s effect is more rapid in onset and lasts longer than caffeine. Guarana could thus be said to be caffeine 2.0.


Caffeine and Effects on Exercise

Exercise and Caffeine

Caffeine is often taken to improve exercise performance. Caffeine improves focus and coordination and promotes fat burning leading to better exercise performance. Caffeine enhances exercise performance through its effects on various systems. These include;

  • Stimulating ryanodine receptors in the muscles to cause stronger muscle contractions
  • Stimulating dopamine release which improves focus, cognition and motivation, enhances energy and reduces fatigue.
  • Increasing circulating levels of adrenaline to stimulate fight or flight responses, thus improving performance
  • Stimulating bronchodilation, improving respiratory efficiency in the process
  • Enhancing lipolysis to produce energy faster.
  • Stimulating the release of endorphins to help with pain and increase feelings of wellness
  • Increasing heat production, thus helping the body burn more calories

Taking high doses of caffeine (5-9mg/kg) before, during and after workouts significantly improves various aspects of performance but is associated with side effects like nausea, nervousness and disturbed sleep. Lower doses of caffeine (<3 mg/kg) produce similar performance-enhancing effects but do not cause significant side effects.

Studies show that caffeine improves workout endurance when used in moderate amounts (3-6mg per kg body weight). Athletes on caffeine show better performance and complete tasks faster than athletes devoid of caffeine. Caffeine also shows a dose-dependent increase in endurance.

Caffeine may benefit high-intensity workout routines. Studies show that experienced high-intensity athletes benefit positively from caffeine, while inexperienced athletes may not. Caffeine reduces fatigue in high-intensity trainers, enabling them to spend more time in routines. However, similar results have not been noticed with inexperienced trainers.

Caffeine is a potent enhancer for weight-loss exercises. Caffeine breaks down fat tissues at a cellular level, increases body metabolism, and stimulates thermogenesis, enhancing fat breakdown. Although exercising induces fat burning, caffeine enhances how much fat can be burned during exercise.

Preworkout caffeine

Taking pre-workout coffee or other caffeinated products significantly boosts cognition and focus, enhances physical performance, reduces fatigue during workouts and boosts fat burning.

Timing the intake of pre-workout caffeine is essential to meet set goals. The International Society for Sports Nutrition (ISSN) recommends taking caffeine 60 minutes before a workout to improve physical performance. A study showed that consuming caffeine 60 minutes before a workout improved static exercises like planks while consuming 30 minutes before exercises improved dynamic exercises like pushups.

The ISSN also recommends taking 3-6mg/kg of caffeine before workouts. Caffeine may be taken in any form, including; brewed, espresso, energy drinks or gums.

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Post-workout caffeine

Taking caffeine after a workout effectively stimulates post-workout recovery. Ingesting caffeine causes muscle glycogen levels to be replenished rapidly after a workout. Replenishing muscle glycogen aids muscle recovery, preventing soreness and muscle fatigue.

Post-workout caffeine may not be necessary following moderate to heavy intake of caffeine pre-workout. However, low caffeine doses pre-workout can be followed by low to moderate post-workout caffeine in any form.

Bodybuilding and Caffeine

Bodybuilding and caffeine

Research shows that low-dose caffeine may increase force and power output in strength-based training like bench presses. However, the research on caffeine’s effect on strength training is inconclusive. Another study showed no difference in muscle strength after caffeine ingestion.

Caffeine does not stimulate muscle growth. Long-term excessive use of caffeine may affect muscle growth negatively. However, moderate doses of caffeine taken pre-workout enhance bodybuilders’ performance and improve efficiency. This improved efficiency helps promote bodybuilding efforts.

Bodybuilders often take caffeine pills to help improve performance. However, caffeine can be taken in any form, including teas and energy drinks. Bodybuilders must regulate caffeine ingestion to prevent adverse effects that may result from excess ingestion;

Bottom Line

Whatever your type of workout –  aerobic, high-intensity, weight-loss or strength training, caffeine can greatly enhance performance and help you reach your goals. You must, however, be careful with its intake. As beneficial as it is, caffeine has many side effects which make it potentially dangerous.

When working out, ensure to keep within the daily limit of caffeine. Essentially, try not to make caffeine intake regular to avoid becoming dependent on it.


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