Do you drink enough water throughout the day? And, do you drink more when you exercise?
I know that I don’t drink enough water; it’s easy to forget when we’re busy.
Water is essential for life. In fact, water is the largest single component of the human body and is involved in almost every process that keeps us functioning normally. It helps to transport nutrients, supports our circulation, helps regulate body temperature, and, it allows our cells and tissues to function properly.
How much water do we actually need?
The answer isn’t quite as simple as drinking a specific number of glasses every day.
Our individual fluid needs can vary considerably depending on factors such as our body size, activity levels, the temperature and humidity around us, how much we sweat, and, what we eat and drink throughout the day.
The U.S. National Academies of Sciences, Engineering, and Medicine gives an Adequate Intake for total water of around 3.7 litres per day for men and 2.7 litres per day for women. However, and this is important, these figures include water from all sources – not just drinking water. Water contained in food, as well as other beverages, contributes to our total daily water intake. The National Academies also makes clear that people who are physically active, or who are exposed to hot environments, will generally need more.
So, there isn’t really a magic number that applies to everyone.
What happens when we exercise?
When we exercise, our need for fluids can increase because we lose water through sweating and breathing.
The harder and longer we exercise, and the hotter and more humid the environment, the greater our potential fluid losses can be.
This is one of the reasons why hydration is particularly important when exercising outdoors, especially during warmer weather.
When we become dehydrated, our body has to work harder to maintain normal physiological function. Fluid loss can affect things such as cardiovascular strain, temperature regulation and how hard exercise feels. Research has also found that dehydration can affect exercise performance, although the effect isn’t as simple as the old idea that any dehydration automatically causes a major drop in performance. The amount of fluid lost, the type and duration of exercise, and, the environment all matter.
For example, research suggests that dehydration is particularly likely to affect endurance exercise when exercising in hot conditions.
Does dehydration affect exercise performance?
This is an area where our understanding has become a little more complex.
You may have heard that losing 2% of your body weight through fluid loss automatically causes a significant reduction in exercise performance. Research doesn’t support such a simple rule for everyone, and, every type of exercise.
A meta-analysis examining exercise-induced dehydration found that the effects depended considerably on the type of exercise being performed. In laboratory-style, fixed-intensity exercise, dehydration of around 2% or more was associated with reduced endurance capacity. However, during self-paced, real-world-style exercise, the effect was much less consistent.
Another systematic review and meta-analysis found that by replacing fluids after dehydration, can improve continuous exercise performance, particularly when exercise takes place in hotter conditions, or, lasts for longer periods.
So, rather than becoming obsessed with hitting a particular number, it makes more sense to consider your individual circumstances. If you’re going for a gentle walk on a cool day, your fluid requirements will obviously be very different from someone running for an hour in hot, and, humid conditions.
Hydration can also help regulate body temperature
One of the most important reasons we sweat during exercise is to help to cool our bodies.
As our body temperature rises during exercise, sweating allows heat to be lost from the skin; the sweat evaporates. However, if we’re losing a lot of fluid, and we aren’t replacing it enough, maintaining our body’s fluid balance, and temperature regulation, becomes more difficult. This is particularly so when exercising in hot environments.
Research has shown that exercising in the heat, while dehydrated, can increase physiological strain and, under some circumstances, impair exercise performance.
What about feeling tired?
Feeling tired during exercise doesn’t always mean you’re dehydrated. There are many reasons why we can feel fatigued, including insufficient sleep, inadequate nutrition, exercising at too high an intensity, and, simply doing more than our body is accustomed to.
However, dehydration can contribute to fatigue, and it can make exercise feel harder.
Research examining perceived exertion during endurance exercise, has found that exercise-induced dehydration can increase how hard exercise feels. So, if you’re exercising and you’re beginning to feel unusually thirsty, tired, dizzy, or unwell, it’s certainly worth paying attention to your body’s signals.
What about drinking before, during and after exercise?
There isn’t one hydration strategy that is perfect for everyone.
For shorter and less intense exercise, simply having access to water and drinking according to thirst may be perfectly adequate for many people.
For longer-duration exercise, particularly in hot conditions or when you’re sweating heavily, paying more attention to fluid intake becomes increasingly important. After exercise, replacing fluids that you’ve lost, helps your body to return towards normal hydration levels.
Therefore, studies show that hydration is important – but, more isn’t necessarily better.
There is also such a thing as drinking too much water, particularly during prolonged exercise, so the goal shouldn’t be to force yourself to drink huge amounts of fluid; instead, think about replacing the fluid you’re actually losing.
Drinking too much water is known as Water intoxication or Overhydration. The dangerous drop in blood salt levels, caused by the excess water, is known as Hyponatremia.
Can urine colour tell us whether we’re hydrated?
Yes, generally, darker urine can be associated with greater concentration, i.e. less fluid in your body, while paler urine can be associated with better hydration. However, urine colour isn’t a perfect hydration test. Things such as certain vitamins, supplements, medications, foods and other factors can change urine colour. Try to think of it as one possible clue, rather than a precise measurement of how much water you need.
Your thirst, urine output, the colour of your urine, your exercise duration, the weather, and, how much you’re sweating, can all provide useful information when considered together.
So, how much should you drink when exercising?
This is where I think it’s important not to overcomplicate things.
There is no single amount of water that every person should drink before, during and after exercise.
Your requirements will depend on:
- How long you’re exercising
- How hard you’re exercising
- Your body size
- How much you sweat
- The temperature and humidity
- Whether you’re exercising indoors or outdoors
- What you’ve eaten and drank throughout the day
- Whether you’ve already started your exercise session dehydrated
For a shorter, moderate workout, you may simply need to drink according to thirst.
For longer exercise sessions, particularly in hot weather, you may need to pay considerably more attention to your fluid intake.
Our Weights2Go Weighted Sports Bottles are designed to work together as a pair, and, they hold just under 2L of water, which will keep you hydrated for some time; although we’re all different, and, need varying amounts of water (or healthy fluids) especially so, when exercising. Plus, if you’re a particularly heavy sweater, your requirements may be very different from someone who barely sweats.
Listen to your body, but also consider the circumstances.
Water doesn’t have to be boring!
If you don’t particularly enjoy drinking plain water, there are lots of simple ways to make it more appealing.
Try adding:
Lots of ice and some sliced lemon. Or perhaps some lime, cucumber, berries, mint or a small amount of fruit juice.
I love chilled water after exercising, especially after being outdoors. Often, after my morning walk or hike, I’ll have a large glass of water. If I’m still thirsty, I may have another glass or two before having a chilled peach-flavoured iced tea; and, honestly, it tastes delicious, and it leaves me feeling refreshed and ready to start the rest of my day.
Weights2Go Weighted Sports Bottles save you from having to carry a separate water bottle while also attempting to juggle a set of dumbbells. Weights2Go is designed to combine it all, for convenience, comfort, and, resistance training with hydration!
Hydrate. Strengthen. Go.
Research & Further Reading
- Institute of Medicine / National Academies of Sciences, Engineering, and Medicine (2005). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. This provides the commonly cited Adequate Intake figures for total water and explains that the figures include water from food and beverages.
- Shirreffs, S. M. (2005). The importance of good hydration for work and exercise performance. Nutrition Reviews, 63(6), S14–S21. A useful review of hydration, exercise performance and the effects of environmental temperature.
- Cheuvront, S. N. & Kenefick, R. W. (2012). Dehydration: Physiology, assessment, and performance effects. This body of research helps explain why the effects of dehydration depend on exercise intensity, duration and environmental conditions.
- McCartney, D. et al. (2017). The Effect of Fluid Intake Following Dehydration on Subsequent Athletic and Cognitive Performance: A Systematic Review and Meta-analysis. Sports Medicine – Open, 3, 20. This systematic review examined 64 trials involving 643 participants.
- Wittbrodt, M. T. & Millard-Stafford, M. (2018). Dehydration Impairs Cognitive Performance: A Meta-analysis. Medicine & Science in Sports & Exercise, 50(11), 2360–2368. This research examined the relationship between dehydration and cognitive performance, including attention and executive function.
- Lorenzo, I. et al. (2022). Impact of Dehydration on Perceived Exertion During Endurance Exercise: A Systematic Review With Meta-analysis. This research looked specifically at whether dehydration makes endurance exercise feel harder.
Disclaimer: This article is for general educational and informational purposes only and is not intended to replace individual medical or professional advice. Fluid requirements can vary considerably between individuals. People with medical conditions or who have been advised to restrict or modify their fluid intake should follow the advice of their healthcare professional.