First rule of hydration is – don’t rely on feeling thirsty!

That sensation is conditioned by habit and gender and doesn’t always correspond to your actual hydration level*. Inversely, you can also perform well in high-octane sports even if you are a little dehydrated. 

The mantra is, keep hydrating frequently. If you’re ambitious about sports achievements, can you make further gains with the right drink ?

Every nutrient in liquid form is absorbed faster than solid form. This is because the whole “churning” part is skipped and can go pretty much straight into the intestine**. That’s the basis of a lot of marketing of sports drinks.

This isn’t overall beneficial. When you absorb your nutrients as a meal, the slower release in the bloodstream works to your advantage. But manufacturers of carbohydrate drinks, protein drinks and caffeinated drinks promise you better sports results with their brand. Let’s examine what fluids do for you first, and then check out their claims.

The function of fluids while exercising

Allowing muscle fibres to contract: your muscles work thanks to the “sliding” of interlaced fibres, actin and myosin. If you’re low on water, the process is inhibited***.

Regulating body temperature: Sweating cools down our skin from outside, as well as regulating the concentration of salt in your blood.  In warm weather, during prolonged exercise, sweat can ratchet up to 5 to 10 litres****! Separately, our blood cools as it’s channeled through the tiny little blood vessels near the surface of the skin 0 our capillaries. 

Continuation of normal processes: Your mind is focused on your sporting challenge, but your body keeps running many other processes in the “background” that still require a fair amount of water. It can be dangerous if sweating denies any other organ access to water*****.

Which drink is best during training?

In short, water. There are no drawbacks to drinking water, only positives.

But you’re probably bombarded with ads for more exciting alternatives!

Caffeinated drinks: Caffeine is the most used psychoactive drug in the world. It stimulates the central nervous system (CNS) by tricking it. It stops a substance naturally produced by your body, adenosine, from binding to your cells. One of the functions of the latter is to help the daily cycle in this way: it very gradually builds up during the day, until you feel relaxed and ready to sleep. While sleeping, you get rid of it and the cycle repeats. For coffee drinkers, adenosine keeps building and building until our body flushes caffeine away and then boom, the “caffeine” crash******. Tiredness hits.

While the caffeine is effective, will it enhance your performance? The World Anti-Doping Association (WADA) banned caffeine alongside terrible stuff like cocaine, anabolic steroids and hGH until 2004. For road cycling, long distance running and soccer caffeine inhibits fatigue. For other sports, the effect is a slightly augmented alertness and focus*******.  Remember, if you opt for high-concentration coffee drinks you run the risk of mild withdrawal syndrome, reduced focusing (when not on caffeine) and increased risk of diabetes and anxiety********. Also, watch the sugar!

Carbohydrate drinks:  these divide in hypotonic, isotonic and hypertonic, all easily explained. Hypo = less, iso = same, hyper = more: these describes the carbohydrate concentration levels relative to your normal bloodstream and will tell you how quickly the carbs are absorbed. Low concentration drinks kick in quicker, but have less energy/calories. But that balance for athletes is a side show, because the real question is, do you need sugars while exercising?

If you have a decent diet, you already have all the energy you need to start your activity. The hard truth is, carb intake before sports is pretty much useless*********.

However, if you’re working out intensely and over time, sipping a beverage containing quickly absorbable energy will limit deteriorating performance. Avoid big volumes and avoid brands that use fructose, for the sake of your stomach. Sold on electrolytes intake, those minerals that are expelled through intense sweating? It is definitely positive to have them in your drink, but guess what? Your ordinary mineral water is already more than likely to contain it.

Protein drinks:  Forget the myth that protein shakes before exercise will increase your performance.  You don’t build muscles from protein shakes, but from  your hard work combined with a correct overall intake of protein during the whole day.  After your session is completed, don’t stress rushing for your shake! Perhaps have a shower, a little chat with your teammates or gym buddies, and then eat a healthy snack containing a good amount of protein. It could be animal, plant, dairy, eggs. With guidelines capping your recommended protein intake at 1.4-2 grammes/kg of bodyweight, you’re unlikely to need a lot of supplements to your diet as it is. And that is aimed at very active people! If you are only recreationally exercising, you should be at the lower limit or slightly below. ******** A daily protein intake high enough to sustain and promote healthy muscle to strengthen is essential, but if it is too much our body will initially discard them, then starting to store them as fat. Probably not what you wanted with your coolly branded protein drink brand…

References

*Cheung  S. S., McGarr G. W., Mallette M. M., Wallace P. J., Watson C. L., Kim I. M., Greenway M. J. (2015) ‘Separate and combined effects of dehydration and thirst sensation on exercise performance in the heat.’ Scandinavian Journal of medical sport science, 25(1), 104-111. 

**Lee J. Y., Jones J. B., Mattes R. D. (2014) Solid Vs Liquid Calories: current scientific understandings. New York: Springer.

 *** & ***** Bernadot, D. (2011) Advanced sport nutrition. 2nd Edn. Champaign: Human Kinetics.

**** Gisolfi C. V.(2003) ‘Nutritional needs in hot environments: applications for military personnel in field operations.’, US Committee on military nutrition research.

******Cooper, C. (2012) Run, swim, throw, cheat: the science between drugs in sports. Oxford: Oxford University Press.

*******Goldstein, R. E., Ziegenfuss, T., Kalman, D., Kreider, R., Campbell, B., Wilborn, C., Taylor, L., Willoughby, D., Stout, J., Graves, B., Wildman, R., Ivy, L. J., Spano, M., Smith, E. A., Antonio, J. (2010) ‘International society of sports nutrition position stand: caffeine and performance’. Journal of the International society of sports nutrition, 7, 5-20.

********van Dam R. M., Hu F. B., Willett W. C. (2020) ‘Coffee, caffeine and health.’ New England journal of medical science, 383, 369-378.

********* Cohen, D. (2012) ‘The truth about sports drinks’ British Medical Journal, 345, 1-8.

**********Campbell B., Kreider R. B., Ziegenfuss T., La Bounty P., Roberts M., Burke D., Landis J., Lopez H., Antonio J. (2007) ‘International Society of sports nutrition position stand: protein and exercise.’ Journal of the International society of sports nutrition, 4(8).

Further reading

Leib D. E., Zimmerman C. A., Knight Z. A (2016) ‘Thirst.’  Current Biology, 26(24), 1260-1265.