The use of supplementation in recreational athletes is higher than ever. Protein shakes, pre-workout and creatine seem to be part of the standard gym kit. Although the utility of some of these supplements has been demonstrated, there is one even more effective and effortless method to improve performance every time you participate in sports. What if I would tell you that this method is also completely free as well as without any health risks? Sounds like a scam right?
Well, it isn’t. All these benefits mentioned above refer to adequate water intake to prevent dehydration before and during physical activity. As indicated by the National Council on Strength & Fitness, 1 endurance starts to drop rapidly with water shortages of 2% and greater. Specifically: this study 2 found that dehydrated cyclist time to exhaustion on a hill climb reduced by 28.6%. Moreover, skill-specific capabilities such as shooting accuracy in soccer or pitching accuracy in baseball were found to decrease at a level of 2% dehydration3. You may be wondering, why would this be a problem for me; I will just drink when I am thirsty. The answer to this is that you will only start to feel thirsty at this 2% shortage 4. In effect, when you rely on your senses, you are already too late and performance is likely to drop.
In contrast to endurance, strength and explosive power seem to be relatively resistant to dehydration 5. Only after a shortage of 5%, short bursts of energy expenditure such as vertical jumps or sprints are negatively influenced 6. This difference between aerobic system performance and anaerobic system performance under dehydration can be explained by the fact that the aerobic system uses water in energy generation while the anaerobic system does not require water 7.
Carlton and Orr who summarised all the scientific literature on dehydration until 2015, confirm these claims 8. More specifically, they state that dehydration appears to harm physical activities with a duration greater than 15 seconds while being irrelevant for activities shorter than 15 seconds. Moreover, for health purposes, shortages of over 5% should be avoided at all times as this may result in heat strokes, cramps, exhaustion and worse 9.
You may be wondering now, how do I prevent dehydration then? A good rule of thumb is to drink 250ML of water every 15 minutes during an average intensity workout and 250 ML every 10 minutes during a heavy workout in more extreme conditions (e.g. heat)10. This approach should guarantee that you drink before being thirsty.
If you want to take a more scientific approach to measure your water requirements during physical activity, you could calculate your sweating rate as demonstrated below. This requires a one-time effort but once calculated, you know exactly how many liter of water to drink every x minutes during your workouts.