Pre-workout supplements are popular. What do they consist off? What do they do? Are they useful? What is the evidence? Are they safe to take? What strikes me, is that the most frequently asked question is: which one is the best? and the question not often asked is: do they work? or are they necessary?
The magic blend
Pre-workout supplements often contain a mystery blend of ingredients ranging from caffeine to BCAAs to creatine to some more exotic ingredients. These supplements are claimed to bring your body in a state of “readiness” for the training! Although there are hundreds of these supplements on the market and they are all different, there seem to be a few ingredients that can be found in most of these products. A recent study showed that 44.3% of investigated supplements contained a proprietary blend of ingredients. This means that the exact amounts are not disclosed and thus it is impossible to link the potential effects to any of the ingredients. If we want to evaluate the effects of these pre-workout supplements, we need to look at the evidence behind each of these ingredients. We will start with some of the most common ones, because if they are in all products, they must be the most effective ingredients. In the infographic the most common ingredients are listed according to a recent publication (1).
Beta alanine ingestion over a period of several weeks can increase the muscle buffering capacity because the concentration of muscle carnosine may increase. One of the side effects of beta-alanine is parasthesia (tingling fingertips and nose). The higher the dose the more severe the side effects. But some people like it because now the supplement you are taking seems to do something... you notice something after taking it... so it must work. The amounts of beta-alanine found in most pre-workout supplements is far too small to have these effects. Besides that, the carnosine concentration needs about 4-6 weeks to increase, thus just taking a small dose just before exercise will have no effect at al.
It is known for a long time that caffeine improves alertness and can improve endurance exercise performance. The evidence that it improves performance during high intensity exercise workouts and resistance training is much less convincing, but it is possible. Caffeine, in whatever form would need to be ingested about 1 hour before the workout. One could also argue that the source of the caffeine does not matter. For example, drinking coffee would have the same effect as the synthetic caffeine in most of these pre-workout products, so we would not necessarily need a pre-workout supplement for this effect.
Branched-chain amino acids or BCAAs is a group of three essential amino acids: isoleucine, leucine and valine. BCAAs are building blocks for protein and leucine also has a role in turning on protein synthesis. Studies have shown that BCAA alone are ineffective in raising protein synthesis and they would have to be ingested with protein. One way to do this is a supplement but chicken for example has more essential amino acids and more BCAA than most supplements. So why not eat the protein. Besides that, this is not an acute effect and there is no need to take it before exercise. Studies show that protein post exercise is at least as effective or more effective. So why not just have a meal after exercise? Also other claims of BCAAs do not seem supported with evidence (read more here).
Citrulline malate is another amino acid that is produced in the body through the other amino acids that are consumed. Some studies have used citrulline as a precursor for arginine, with the goal to improve blood flow. The effects have been very small and several studies have not been able to find any effects.
Creatine is a popular supplement. It is one of the few that has evidence that it can be beneficial in some situations for some people. If body stores of creatine are suboptimal, creatine supplementation for 5 days (high doses of 20 g per day) have been shown to restore the creatine stores. Studies have shown that higher muscle creatine concentrations are linked to improved repeated high intensity exercise performance. Creatine ingested at 3g/day for 30 days will achieve the same. However, ingesting 1-3 grams of creatine just before a workout will not improve that workout.