Pre-Workout Supplements- Do they work?

Why do people drink pre-workouts?  

The three most commonly cited reasons to take pre-workouts are to enhance 1) energy and focus, 2) muscular endurance, and 3) muscle blood flow.  

Let’s take a quick look at the evidence behind each of these hoped-for effects. Bear in mind, with the wide array of pre-workout formulae, each containing varying ingredients, it is hard to make sweeping recommendations, but here is a glimpse of what the current research shows us:

Can they enhance energy and focus? 

Likely yes. Ingesting a pre-workout has been found to enhance performance on cognitive tasks, such as reaction time tests and surveys of vigor, performed 45 min later. Subjective feelings of greater vigor have been noted after the consumption of caffeine-containing pre-workouts. So yes, pre-workouts look to be able to make you feel more energetic and alert. 

Is this something more than you can achieve with a cup of coffee? Probably not.

Can they enhance muscular performance? 

Possibly. Several studies show that multi-ingredient pre-workout supplements can lead to enhanced exercise performance over a placebo in a variety of tasks, including both endurance and strength-power movements. Findings are inconsistent though, as other studies find no measurable effects. Again, the diverse nature of products and ingredients comprising pre-workouts makes any sweeping recommendations of pre-workouts impossible.

Further complicating exercise studies of pre-workouts are differences in the training status of subjects and in the types of exercise tested. Also, there is evidence that an individual’s belief that these supplements can be helpful contributes as greatly to whether or not one sees enhanced exercise performances as any direct action the pre-workout ingredients may have on muscle function. 

For direct effects on muscle performance, look to one of the most common ingredients among pre-workout supplements: caffeine. Caffeine’s effectiveness at enhancing exercise performance shortly after ingestion is well–documented. At least one study found muscular endurance performance was improved more following the ingestion of caffeine alone over the consumption of a pre-workout containing caffeine plus five other ingredients.

So again, when looking at pre-workouts’ role in enhancing exercise performance, is this something more than you can achieve with a cup of coffee? And again, probably not.

Of note, one of the common pre-workout ingredients, niacin, has been associated with reduced exercise performance. Niacin has been found to potentially worsen fatigue. This ergolytic effect is attributed to niacin’s apparent interference with one’s ability to access the fat as an energy source.  

Can they enhance muscle blood flow? 

Possibly, though the fitter you are the less likely this will help. Exercise alone, without any supplementation, increases blood flow to active tissues by dilating the arteries around them. Habitual training enhances one’s ability to increase blood flow to active muscles. Whether pre-workouts can help increase blood flow or not is questionable, with mixed findings either supporting increased arterial diameter after pre-workout consumption versus no measurable effects.

Individual supplements (arginine, citrulline) that increase blood flow during exercise have generally been found to exert a stronger effect in less-trained subjects, so I would posit that this would also hold true for multi-ingredient pre-workouts, and only untrained or recreationally-trained people would likely see a benefit.   

So to wrap up, there is evidence that pre-workouts can be helpful in increasing arousal, enhancing exercise performance, and (at least in novices) increasing blood flow. Most of the performance-enhancing benefits from pre-workouts probably come from a combination of the effects of caffeine and a placebo effect that the blend of ingredients is supposed to help you. Also, avoiding pre-workouts that contain high doses of niacin might be a good idea!

In Part 3 – I will discuss the safety concerns of using pre-workouts. 

If you missed Part 1 of this series, check out Let's Talk About Pre-Workout Supplements.

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