Quick answer: sports science bodies around the world agree on one simple idea: start exercise already well hydrated. Research shows many people arrive at training under-hydrated, and starting that way can make the same session feel harder, especially in the heat. Drinking steadily in the hours before you train, and having some sodium with your fluids, is the practical way to turn up ready.
Most hydration advice is about what to drink during or after a workout. The research tells a slightly different story. The moment that gets missed most often is the one before you start. Here's what the science says about pre-workout hydration, and how to make "start hydrated" an easy habit.
What the experts recommend
The world's major sports nutrition bodies all put pre-exercise hydration first:
- American College of Sports Medicine (ACSM): the goal of drinking before exercise is to "start the activity euhydrated", meaning properly hydrated, with normal electrolyte levels.
- Academy of Nutrition and Dietetics, Dietitians of Canada and ACSM (2016): drink around 5 to 10 mL per kg of body weight in the 2 to 4 hours before exercise, aiming for pale yellow urine.
- Sports Dietitians Australia: "always start exercise well hydrated". Their 2020 position statement on exercising in hot environments says athletes should aim to begin exercise hydrated.
- International Society of Sports Nutrition (2018): "it is highly recommended that individuals are adequately hydrated" before starting exercise.
How many people start behind?
More than you'd think. Studies that test urine before training keep finding the same pattern, all over the world:
| Group | Arrived under-hydrated |
|---|---|
| Soccer players (review of 24 studies) | About 80% |
| Elite young athletes, Greece | 76% |
| US college athletes (263 tested) | About two in three |
| Professional athletes (NATA summary) | More than half |
It's not just athletes. Research on outdoor and mining workers in hot parts of Australia found most were under-hydrated at the start of their shift, and surveys across 13 countries found about 6 in 10 men and 4 in 10 women drink less than the recommended daily amount.
Why starting hydrated matters
- Performance: a 2020 meta-analysis of 15 studies found that starting aerobic exercise under-hydrated lowered performance by about 2.4%, in temperatures from 19 to 40 °C.
- Heat strain: in a study of trail runners in the heat, each extra 1% of body weight lost as fluid was linked to about a 0.22 °C higher core temperature and a heart rate about 6 beats per minute higher. The under-hydrated runners were also slower.
- Focus and mood: losing more than about 2% of body weight in fluid is widely linked with poorer thinking, and studies in young adults found mood and concentration dipped at smaller losses of around 1.4 to 1.6%.
The takeaway isn't to drink huge amounts. Major guidelines say most recreational exercisers don't need extra fluid beyond normal. It's simply to make sure you're not starting behind.
Where sodium fits
ACSM notes that having sodium with your fluids, from a drink or salty food, helps stimulate thirst and helps your body hold on to the fluid. In lab studies, drinks with moderate sodium levels were retained better than plain water or low-sodium drinks. This is why many sports dietitians suggest a salty snack or a sodium-containing drink in the lead-up to long or hot sessions. Very large "sodium loading" doses are a specialist strategy for elite athletes and should be done with professional advice.
A simple start-hydrated routine
- The night before: drink normally with dinner. Don't skip fluids just because you're busy.
- On waking: have a glass of water before coffee.
- 2 to 4 hours out: drink around 5 to 10 mL per kg of body weight (about 375 to 750 mL for a 75 kg person), with a meal or snack that includes some salt.
- Check the colour: pale straw is the goal. If it's dark, have a little more about 2 hours before.
- Make it something you'll actually drink: research shows cool, flavoured drinks get drunk more than warm or plain ones.
Hydrate before. Go further, naturally.
Uthrive is a lightly sparkling natural hydration drink with 260mg sodium and 130mg potassium from Lake Deborah salt, real fruit and no added sugar. A cold one is an easy part of your before routine. Try Passionfruit, Orange, Pineapple or a mixed box.
More reading: how much to drink before exercise, gym hydration before, during and after and how sodium and potassium work together.
Frequently asked questions
Should I drink before a workout?
Yes. Sports nutrition guidelines recommend starting exercise well hydrated, which means drinking steadily in the hours before, not just at the start line.
How long before exercise should I drink?
Guidelines suggest drinking in the 2 to 4 hours before exercise, so your body has time to absorb what it needs and pass the rest.
Is water enough before training?
For most short sessions in mild weather, water and normal meals are enough. For long, hot or very sweaty sessions, including some sodium from food or drink can help.
How do I know if I'm hydrated before training?
Pale straw coloured urine is a simple guide. Dark urine, thirst or a dry mouth are signs to drink a bit more.
Sources: Sawka et al., ACSM position stand, Med Sci Sports Exerc 2007; Thomas, Erdman & Burke, J Acad Nutr Diet 2016; McDermott et al., NATA position statement, J Athl Train 2017; Kerksick et al., J Int Soc Sports Nutr 2018; McCubbin et al., Int J Sport Nutr Exerc Metab 2020; Sports Dietitians Australia, Fluids in Sport; Chapelle et al., Nutrients 2020; Arnaoutis et al., J Strength Cond Res 2015; Volpe et al., J Athl Train 2009; Miller & Bates, J Occup Health Safety Aust NZ 2007; Ferreira-Pêgo et al., Eur J Nutr 2015; Deshayes, Jeker & Goulet, Sports Med 2020; Casa et al., J Athl Train 2010; Ganio et al., Br J Nutr 2011; Armstrong et al., J Nutr 2012; Maughan et al., Am J Clin Nutr 2016. General information only, not medical advice.
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