Once upon a time, a banana and a strong black coffee sufficed as a pre workout, giving you all the energy you might need to get you through a gruelling session. However, as fitness trends change and research persists, a whole sub industry of pre workout supplements has sprung up and a great many gym goers swear by them.

As a trainer, it’s common enough to come across both clients and casual gym buffs talking about their pre workouts, complaining about how tough their workouts seem when they don’t remember to take them, and attributing new PRs and gains on them.

But what exactly are they; what benefits will they give you; and, crucially, how long will their effects persist?

What are pre workout supplements for?

A pre workout supplement is any supplement designed to improve performance if you take it before training – or at least that is marketed as such. Usually it will be a powder to mix into your drink, or else a capsule to pop at the appointed time. They will generally give you some form of increased energy and focus.

Almost every supplement and sports nutrition company going has their own in-house brand, with different ingredients and formulas giving different effects. Outside of the intended effects of the supplement, therefore, there is little else to define a ‘pre workout’. There will of course be some ingredients that pop up more regularly than others – which I’ll go through in more detail below – though these are more like usual suspects than necessary components.

Suffice it to say for the moment, therefore, that a pre workout will generally give you some form of immediate energy boost to get you through your training, with some kind of slower released energy to keep you at your peak for longer.

To this end, some pre workout supplements contain carbs, though others are carb and calorie free. Others will give you caffeine, beet juice or some form of amino acid to prime your fight or flight response and increase vasodilation. Others include various more exotic ingredients to elicit responses such as levels of insulin or testosterone – though these are usually add ons to the above core ingredients.

How long do pre workout supplements last?

Now to get straight to the point and answer the question itself. In healthy, average adults with no particularly sensitivities or high tolerances for the components, most pre workout supplements should last an average of 1.5-2 hours. This is the benchmark for your supplements- any deviation from this range and you might want to reconsider your regime. There are a few factors that can decrease the potency, effects and timing of your pre workout supplement. These include:

  • Dehydration: water is your body’s lifeline and it drives nutrients to all of your cells. Without adequate hydration, it doesn’t matter what nutrients you take in- they will never be as effective as they should be.
  • Malnutrition: this is second on the list of importance after water. If you don’t eat enough to fuel your muscles and allow recovery, if you don’t take in energy giving nutrients, then no supplement will be of use. Always remember that the clue is in the title: supplements supplement, they can only top up adequate nutrition, not replace it.
  • Fatigue: once more, supplements can only supplement. Remember that, repeat it to yourself, and then repeat it again. If you’re not getting enough rest- time in which to both rebuild and recover, and to replenish energy stocks- then taking a bit of caffeine will not do much for you. There’s no replacement for proper, deep sleep- aim for around 8 hours per night if you can.
  • Over eating: this is the flip side of malnutrition, when you take in too much- or at least too much too close to a workout or training session. If your body is already putting energy and effort into the digestive process then it won’t be able to absorb the supplements you take- including your pre workouts. (It’s also worth remembering that training on a full stomach can lead to messier side effects- you don’t want to be the one puking at your local gym. Trust me.)
  • Tolerance: your body can build up a tolerance to almost any drug or stimulant- this is no different with the various peppy compounds you will find in your average pre workout formula. If you have too much caffeine in your diet, or if you take the same pre workout too often and for too long, you will find that they begin to lose potency.

If you find your pre workout supplement losing its efficacy or potency, it could be worth looking down this list and manipulating whichever variables that you think relevant. For example, if you are sleeping less than 6-8 hours on average each night, your pre workouts will not work so well- try to make room for a greater degree of rest to bring them up to full potency. It’s common- even inevitable- that you will build up a tolerance to many supplements you take.

Every single person who takes pre-training supplements develops a tolerance to it at some point. The only way to avoid that is to cycle off the supplement periodically so that your body stays receptive to it.

If and when this happens, consider detoxing for a while- going cold turkey and removing them from your supplementation regime for a couple of months- in order to reestablish your sensitivity. Alternatively, consider changing the type of pre workout you are using every few months to stop yourself from getting too accustomed to any particular ingredient or product.

What’s in your pre workout supplement?

So, now we know what pre workouts are for, let’s look in a little bit more detail about what they usually contain. Below is a list of the most commonly included ingredients you might find in a pre workout. Though some brands like to play around and include various weird and wonderful compounds in their products, most pre workouts contain permutations and derivations of the four key ingredients mentioned above: caffeine, carbohydrates, amino acids and, perhaps odd sounding, beetroot juice.


This is an obvious one, really. If you’re about to put some hard time into your workout, you will need plenty of fuel. This comes in the form of carbohydrates. In a pre workout supplement, a carb boost like this will help in providing your muscles with plenty of glycogen, which your body will use plentifully during intense training.


This comes as welcome news to anyone like me who won’t face the day without a mug or two of steaming coffee. Most pre workout supplements will give you a decent dose of caffeine. The research is in line with anecdotal evidence here: caffeine’s ability to improve energy levels, increase alertness and brain function and dull pain is fairly well documented. Taking a pre workout with caffeine included will definitely give you the added kick you need to inspire you to ever greater feats in the gym.

Amino acids

Proteins are made of a collection of amino acids, and complete proteins are made of all twenty amino acids. Of these, there are nine essential proteins which our bodies can’t create and so must come from dietary intake, and of these, three are the particularly important branched chain amino acids leucine, isoleucine and valine. We need these both to build muscle and to increase and maintain energy levels. Their ability to enhance endurance performance in intense training regimes has been well documented, making them a sure bet for inclusion in pre workouts.

You will often find nitric oxide included in the list of amino acids, typically labelled arginine. Nitric oxide is a naturally produced gas that your body makes in order to aid communication between cells. It is used as a supplement mostly for increased blood vessel dilation- this in turn should lead to improved protein synthesis. Research is as yet undecided on its efficacy, with results being quite mixed thus far. However, there are plenty of reports of a minor increase to anaerobic threshold over a period of weeks in those who take arginine supplements.

Beetroot juice

This might not be quite what you were expecting to find in a list of pre workout supplements. However, beetroot juice is most definitely a usual suspect in such products, and deservedly so. Some take it as a component of a supplement whilst others prefer to drink it straight. Whichever way you decide to ingest it, beetroot juice is rich in nitrates and has been proven to improve vasodilation and increase levels of nitric oxide in your blood. Taking in beetroot juice regularly will help you to work out harder, for longer, with greater muscular adaptation as a result.

How do you know when your pre workout supplement is working?

One of the key ways of telling that your pre workout supplements have retained their efficacy for you and that you have got your timings right is whether or not they are working, obviously. So, how do you know if your pre workouts are still doing what they should be doing?

Most of the immediate, tangible effects that you can expect from your pre workouts will come from the stimulants inherent to their recipes. These effects are easy to take the measure of on an ongoing basis- if you feel  focused and energised after taking them then it’s a fair bet that they are still working. If not, you will want to change up your regime or perhaps consider a brief detox to increase your sensitivity to them.

If the product contains Beta-Alanine, which is a common ingredient in many pre workout supplement recipes, then you should feel a tingling sensation after taking them. Many athletes who take pre workouts will be all too familiar with this feeling- some newcomers often report panic at feeling it for the first time. However, it’s as it should be and is normal and safe- it’s a usual histamine response combined with acute paresthesia caused by the nerve endings right beneath the skin being overstimulated by Beta-Alanine. It should begin at around fifteen minutes post consumption and will typically carry on for around 30- 90 minutes. It should not be feared. If this sensation diminishes or doesn’t manifest at all then you will know that new supplements are needed.

What you should be looking out for:

The mainstay of pre workout supplement ingredients listed above are well documented as having performance enhancing properties. Caffeine, BCAAs, carbohydrates, beetroot juice, and the popular muscle-building supplement creatine monohydrate are all common pre-workout supplement ingredients that have been shown to work. If any of the effects talked about below start to diminish, you may want to think about replacing your supplements with different ones for variety’s sake.

Caffeine will obviously boost energy and alertness and has been proven to do so even in those with high caffeine tolerance from regular consumption (the coffee drinkers out there). Research has shown that it may support athletic performance as well. It can act to decrease perception of exertion, so that harder workouts will feel easier. The prevailing theory behind this is that caffeine helps both to preserve glycogen whilst burning more fat for fuel. This would stretch out your energy stores for longer. As well as this, caffeine is a well known mild painkiller, so that perception of fatigue will be lessened. If you find that your endurance is slipping in the gym after taking some slightly older pre workouts, it could be that your sensitivity to its caffeine content has waned.

Carbohydrates will have the effect you would expect – and that any carbs from any source will have on you – in giving you a plentiful source of energy to be released throughout your training. Most trainers would recommend some form of carbohydrate intake before working out (unless you are specifically carb depleting, of course). When you are training – especially at high intensities – you will be using up your body’s supply of glycogen and blood glucose (the carbs stored in the body) so making sure you have enough to get you through your workout is a must. 30 to 60 grams pre training should do it, though I would like to underline the fact that these can come from a multitude of sources (my banana at the article’s start would be a great source, for example).

Beetroot has been shown to increase the body’s levels of nitric oxide, which I mentioned before, as well as improving cardiovascular performance. The natural vasodilatory properties to be had from nitric oxide (expanding the body’s blood vessels and increasing blood blow) means that the exertion placed on your heart is decreased. Look out for these benefits during training- if you find that your heart rate is spiking where before it was fairly even, or that you’re not able to get the most out of your body at each BPM stage, it could that you need to take your pre workout closer to the beginning of training.

Creatine monohydrate, often contained in pre workout supplements, is derived from three amino acids that are stored in the muscle tissue for use as a source of quick release energy. Studies have shown that it works, with high dose supplementation aiding in mass and strength building. However, it does not have an acute effect, unlike stimulants such as caffeine. This means that it isn’t dependent on being taken at a certain time, but rather works best by building it up in your system as a readily available resource. Using it in a pre workout supplement is fine, but you can take it any time of day and it will work just as well.

Many of the other ingredients found in pre workout supplements are pretty useless and will be unlikely to make any kind of tangible difference. Always bear in mind that trials are often funded by supplement companies- if a trial says that such-and-such a formula works because of its key, secret ingredients, take it with a pinch of salt. Largely, you will want to stick to the ingredients and compounds listed above- if these all still work for you then your pre workout supplement will be spot on.