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Caffeine for Lifters: A Dietitians Guide 

Caffeine for Lifters

Caffeine has long been used in sports to improve performance.

In endurance sports, the research has been clear for decades that it improves performance.

A large percentage of people who lift weights consume caffeine. Most people likely are just taking it because it hypes them up and makes them feel more motivated to train.

Something that is a little less commonly known is that caffeine literally improves performance in those who lift weights.

This article will be covering:

  • How caffeine helps improve performance.
  • What the research shows.
  • How you should personally use caffeine, should you wish to.

How Does It Work?

Caffeine Mechanism of action diagram
Image credit:

While there are a lot of proposed mechanisms, the current consensus is that a large portion of the benefit comes from changes in CNS activity.

Since caffeine has a chemical structure that is similar to adenosine, it can bind to adenosine receptors. This contributes to a lot of the effects of caffeine including improved alertness and wakefulness.

This is the same reason why there is a reduction in pain and perceived effort following caffeine consumption. It also contributes to the ability to produce force and delay fatigue.

That being said, this mechanism does not explain all of the benefits. Another aspect that helps explain the boost in performance is that caffeine can help with calcium transport, which can help with muscular contractions.

How Much Does It Help?

In terms of how much caffeine can help, it likely depends on which aspect of lifting you are referring to.

Let’s start at 1RM performance, which is important to athletes such as powerlifters. This area does not have much research yet, but a meta-analysis on the topic has found that caffeine when dosed appropriately does improve performance in 1RM attempts.


The average improvement is ~3.2% based on that research. This is a small improvement but is also meaningful for a lot of people who are trying to optimise performance.

Another meta-analysis that looked at the effects of caffeine on muscular strength had similar findings. As an additional note, they found that the benefit was almost double for muscular endurance. Higher rep sets likely benefit from caffeine more than lower rep sets.

This concept was further built upon with an umbrella review from 2019 on the topic. This review covered 21 meta-analyses on caffeine and sports performance. So it basically was a summary of ALL the research up until 2019.

This review identified that endurance sports benefitted most from caffeine. Higher rep sets for muscular endurance showed improvement as well, but to a lesser extent than aerobic activities. And power-based activities such as jumping or 1RM attempts benefitted to a lesser extent once again.

To be clear though, although power-based activities benefitted less, they still showed a statistically significant improvement. So there are still benefits.

What Are the Downsides?

As most people are aware, there are downsides to caffeine. While there are performance benefits, it is worth acknowledging the downsides and finding a favourable balance.

Caffeine and Sleep

The impact of caffeine on sleep is the most common concern. And it is a very real concern.

Research on caffeine consumption (400mg) taken 0, 3 and 6 hours before bed has shown that all 3 of those conditions significantly disrupted sleep quality and quantity.

Caffeine 0, 3 and 6 hours before sleep
Image Credit: Jorn Trommelen

Even though there are benefits to caffeine, if you train in the evening (or within 6 hours of going to sleep) it likely is not a good trade-off to have caffeine prior to your workout.

While caffeine can help your performance a bit, good quality sleep is very important.

There can be exceptions to this though. For example, if somebody had a powerlifting competition in the evening, it could still be worthwhile since the focus is more on performance in that event. Getting good sleep is always a good thing but might be a lower priority on that occasion.

Another exception could be based on your metabolism of caffeine. There are genetic differences between people.

On average the half-life of caffeine is ~5 hours. But this ranges from 1.5-9 hours depending on your individual situation. Somebody who is in a situation where the half-life is 1.5 hours probably does not need to worry about this issue as much.

Caffeine and Anxiety

It is clear that caffeine can increase anxiety in certain people, particularly at higher dosages.

From a life perspective, this might not be a good trade-off for a lot of people.

Since the performance improvement is relatively small, it would not make sense to make large sacrifices elsewhere to facilitate them.

Even looking at the performance side of things, if you experienced a lot of anxiety, there likely would be a reduction in performance related to that too.

Adjusting dosages lower, or just not having caffeine, would likely be the best course of action in those cases.

Other Aspects of Health and Safety

Caffeine and Blood Pressure Chart

For people who do not regularly consume caffeine, there can be acute changes in blood pressure. Habitual consumers likely experience less of this effect.

This might be relevant for those who are concerned about cardiovascular conditions that they might be at risk of.

Other risks of caffeine often occur at excessively high dosages, which are beyond the dosages required to optimise performance.

For example, 7 out of 10 women ingesting 9mg/kg reported adverse effects such as tremors, dizziness, vomiting and sweating. More context around dosages will be added later, but this is a very high dosage.

Research on Different Dosages

A lot of recommendations on caffeine for sports performance involve various ranges such as 1-3mg/kg, 3-6mg/kg or >6mg/kg.

It seems that as little as 1-3mg/kg is enough the reduce the rate of perceived effort. So if somebody was just seeking that effect, or wanted some more motivation for training, this could be enough.

For physically improving performance in general, the current consensus is that 3-6mg/kg is the gold standard.

For strength athletes, it seems as though the higher end of that recommendation (5-6mg/kg) is typically the most effective.

Going significantly higher than that range often comes alongside downsides without any further benefits.

A few things worth noting are:

  1. There is a lot of individual variation. Some people benefit from higher or lower dosages than these numbers.
  2. 5-6mg/kg is actually a relatively large amount. For a 100kg athlete, this is 500-600mg. One standard shot of coffee is around 80mg of caffeine on average (although there is a lot of variation).

Does Caffeine Tolerance Matter?

At this stage, the research seems mixed. The current consensus is that:

High habitual intake of caffeine does seem to reduce the benefit of caffeine when consumed for performance purposes.

Consuming a slightly higher amount of caffeine than usual intake can potentially offset this issue.

If habitual intake is very high, it probably does not make sense to go higher than that level.

Withdrawing caffeine leading up to competition and then reintroducing it has theoretical merit. The research that is available at this stage has not shown it to consistently provide a noticeable benefit though.

Withdrawing from caffeine also comes alongside downsides, such as headaches among other stuff.

In a perfect world, regular caffeine intake should be <3g/kg/day, which seems to mitigate all these issues when you want to use it for performance.

Dosage and How to Take

A lot of what has been spoken about has been pretty theoretical, so now we will look at it from a practical perspective.


As mentioned, the ideal dosage for most people is ~5-6mg/kg. This should be adjusted based on your individual situation. Some people benefit from more, some people benefit from less.

A Note on the Caffeine Content of Coffee

The caffeine content of coffee is highly variable.

One study from the Gold Coast identified that espresso from different coffee shops could range from 25-214mg of caffeine.

Ben Desbrow Espresso Caffeine Variability

If you are just trying to get the benefits of alertness or reduced perceived effort coffee is probably fine.

For trying to optimise performance though, trying to get there solely through coffee could be a bit of a risk. If the caffeine content was significantly above what you would expect, you could dramatically overshoot the targeted range.

Alternatively, if the caffeine content was lower than expected, you might not reap the full benefits.

Amounts in Different Sources

Knowing the targeted dosages is helpful, but only if you know what this looks like in practice. So the below image goes through some amounts of caffeine in different sources.

Caffeine Content of common australian products

Different Timings in Relation to the Source

It is also worth knowing that caffeine typically peaks in the blood about one hour after consumption. The effects typically take ~15 minutes to become apparent.

The source matters dramatically though.

Caffeine coming from gum or capsules peaks at the 30-minute mark on average.

Revvies Energy Strips

Caffeine in chocolate or cola has had research showing that it might take as long as 90-120 minutes.

As a simple rule, I suggest having caffeine ~30 minutes prior to training if you are going to have it. There is often 15-30 minutes of warm-up time to be factored in too, which makes this timing work well.

Depending on the source, you could make arguments for different timing though.

Practical Summary

Caffeine can clearly help performance. It is an option that I think is somehow both commonly underused and overused by the lifting community though.

Some people rarely take it, even if they do not experience many downsides from it, so they miss the potential performance improvements. Or if they do take it, they take a sub-optimal dosage.

Other people take high dosages within a few hours of trying to sleep, so the downsides clearly outweigh the benefits.

Then there are a bunch of people with other unique situations that can affect their dosages and what would be ideal.

The research supports an average of 3-6mg/kg of body weight being beneficial for performance. The top end of that range is likely ideal for people trying to optimise their lifting performance.

Caffeine is certainly not necessary, but if it is used well, it can help performance.

By Aidan Muir

Aidan is a Brisbane based dietitian who prides himself on staying up-to-date with evidence-based approaches to dietetic intervention. He has long been interested in all things nutrition, particularly the effects of different dietary approaches on body composition and sports performance. Due to this passion, he has built up an extensive knowledge base and experience in multiple areas of nutrition and is able to help clients with a variety of conditions. One of Aidan’s main strengths is his ability to adapt plans based on the client's desires. By having such a thorough understanding of optimal nutrition for different situations he is able to develop detailed meal plans and guidance for clients that can contribute to improving the clients overall quality of life and performance. He offers services both in-person and online.