Hydration and Electrolytes for Training: How Much Water You Need

You probably think about protein, sets and sleep far more than you think about water. But hydration for training quietly shapes how hard you can push, how well you handle heat and how you feel the next morning. The good news: getting it right takes a few simple checks, not a complicated formula.

How much water do you need each day?

In 2004 the U.S. National Academies of Sciences, Engineering, and Medicine (NASEM) set an adequate intake of about 3.7 litres of total water per day for men and 2.7 litres for women. That figure includes water from all drinks and from food. Food usually supplies about 20% of it, so the drinking part for an average man works out to roughly 3 litres.

Two points are often missed. First, this is an adequate intake, not a strict target. The same report said most healthy people meet their needs by letting thirst guide them. Second, it applies to a temperate climate and ordinary activity. The report noted that long physical activity and heat increase water losses, and that very active people in hot weather can need six litres or more a day.

Tea, coffee and milk all count towards your fluid total. Mayo Clinic notes that caffeinated drinks contribute to daily water intake, though it is wise to limit sugar-sweetened ones.

A simple daily baseline

• Keep a bottle at your desk and drink with each meal.
• Check your urine colour once or twice a day (more on that below).
• Add extra fluid on training days, in hot weather and when you are at altitude or on a long flight.

Sweat loss and the 2% idea

The American College of Sports Medicine (ACSM) position stand on exercise and fluid replacement is still the standard reference here. Its main points are useful for any man who trains:

• Water deficits of about 2% of body weight or more can impair aerobic performance, particularly in warm weather, and may affect mental performance.
• Strength and short, anaerobic efforts appear less affected, even at 3–5% deficits.
• Sweat rates often range from 0.5 to 2 litres an hour, depending on body size, intensity, weather, clothing and heat acclimatisation.

For an 80 kg man, 2% is 1.6 kg. You could lose that in a long run, a hard football game or a few hours fielding in the sun. You are unlikely to lose it in a 45-minute lifting session indoors.

The 2% figure is a rough guide, not a cliff. The practical goal is to avoid large deficits during long or hot sessions, not to stay at zero.

Find your own sweat rate: the weigh-in test

Because sweat rates vary so widely, ACSM recommends building a personal plan from body-weight checks. It is easy:

1. Weigh yourself just before training, after using the toilet, in minimal clothing.
2. Train as normal. Note how much you drink (in litres).
3. Towel off and weigh yourself again in the same clothing.
4. Sweat loss (litres) = weight before − weight after + fluid drunk. Divide by hours trained to get your hourly rate.

Repeat this in cool and hot conditions to learn your range.

For morning checks, ACSM suggests weighing yourself first thing after urinating over a few days. Normal day-to-day swings are about 1%, so a sudden bigger drop can be a sign you are behind on fluids.

Urine colour: a quick daily check

Health agencies use urine colour charts for heat safety. NSW Health in Australia, for example, describes light, plentiful, odour-free urine as a sign of good hydration, and darker, strong-smelling, small amounts as a sign you need to drink.

Two caveats. Some foods, medicines and vitamin supplements can change urine colour even when you are well hydrated. And if your urine is completely clear all day while you keep forcing drinks, you may simply be drinking more than you need.

Before, during and after training

Before

ACSM suggests drinking slowly about 5–7 ml per kg of body weight at least four hours before exercise. For an 80 kg man that is roughly 400–560 ml. If you are not passing urine or it is dark, add about 3–5 ml per kg around two hours before. A salty snack or meal helps you hold on to that fluid.

During

For most gym sessions under an hour, sip water when you are thirsty. That is enough.

For longer or hotter sessions, the aim is to limit loss to a modest level, not to replace every drop. Use your sweat-rate data to plan a comfortable amount, drink at regular breaks, and let thirst fine-tune it.

After

If you need to rehydrate fast, for example between two matches or before another session the same day, ACSM suggests about 1.5 litres of fluid for every kg of body weight lost, spread over time and with some sodium. The Australian Institute of Sport (AIS) gives a similar range of 1.2–1.5 times the deficit over two to four hours. If you have a full day to recover, normal meals and drinks will usually do the job.

Sodium: when it matters

Sweat is not just water. ACSM reports that sweat sodium averages about 35 mmol per litre, with a wide range of roughly 10–70 mmol per litre. In plain terms, a litre of sweat can carry from a few hundred milligrams to well over a gram of sodium, depending on the person.

For short sessions, you replace that easily with your next meal. Sodium becomes more important when:

• Sessions last more than about an hour, especially in heat.
• You sweat heavily or see white salt marks on your kit.
• You train or play twice in one day.
• You need to rehydrate quickly after a big fluid loss.

ACSM suggests about 0.5–0.7 g of sodium per litre of fluid for exercise longer than an hour. The AIS uses the same range. That also makes drinks taste better and helps your body keep the fluid.

Cricket in the heat: a real-world example

A day of cricket is a classic case. Players are outdoors for many hours, often in strong sun, and fast bowlers work hard in repeated bursts. Batters wear pads, helmets and gloves that trap heat.

For a long match day in the heat, a sensible plan looks like this:

• Arrive hydrated: normal fluids the day before and a drink with a salty breakfast.
• Drink at every break (drinks, lunch, tea) according to thirst and your known sweat rate.
• Use a sodium-containing drink or salty food during the day, especially if you sweat heavily.
• Weigh yourself before and after a few matches to learn your pattern.
• Rehydrate with fluid plus salty food in the evening.

Hyponatremia: why more water is not always better

Exercise-associated hyponatremia (EAH) means blood sodium falls too low during or up to 24 hours after exercise. The 2015 international consensus statement, published in the Clinical Journal of Sport Medicine, identified the main cause as drinking more fluid than your body can lose through sweat and urine.

Early EAH can cause mild or no symptoms. More severe cases can cause headache, vomiting, confusion and seizures, and they can be life-threatening. The consensus panel advised using thirst to guide drinking, rather than forcing fluids beyond it.

The AIS adds an important point: extra sodium does not make overdrinking safe. Avoiding large excess fluid is what protects you.

Signs you may be overdoing it:

• You weigh more after a long session than before.
• You feel bloated, nauseous or have a headache despite drinking plenty.
• Your urine is completely clear all day and you still force drinks.

Are electrolyte drinks worth it?

For most training a busy man does, no. Water plus regular meals covers it. A 40-minute strength session or a 30-minute run does not need a special drink.

Electrolyte or sports drinks are worth considering when:

• You train or play for more than about 60–90 minutes, especially in heat.
• You are a heavy or salty sweater.
• You need to rehydrate fast after a big loss.
• You want sodium without calories, for example during a calorie deficit (choose low-sugar versions).

The AIS lists these same kinds of situations. Plain options work: water with a salty snack, a pinch of salt in a homemade drink with some fruit juice, or salted buttermilk (chaas) or coconut water with a salty snack. If you go long and hard, carbohydrate also helps: ACSM suggests about 30–60 g an hour for intense efforts lasting an hour or more.

If you are building an aerobic base, our Zone 2 training guide shows how to train longer sessions sensibly. And if you watch your salt for blood pressure, read our guide to lowering blood pressure naturally before adding electrolyte products.

A simple hydration plan for men over 35

Low energy is not always about sleep. If you often feel flat in the afternoon, check fluids first, then look at the other causes in our guide to why you feel tired all the time after 35.

FAQ

Do I need 8 glasses of water a day?

There is no single magic number. NASEM’s adequate intake for men is about 3.7 litres of total water a day, including food and all drinks. Most healthy people meet their needs by drinking to thirst, then adding more on hot or training days.

Does coffee dehydrate me?

Not in normal amounts. Mayo Clinic notes that coffee and other caffeinated drinks count towards your daily fluid intake.

Should I drink before I feel thirsty?

For most training, drinking to thirst works well and helps avoid overdrinking, which is the main cause of exercise-associated hyponatremia. In very long or hot sessions, a simple plan based on your sweat rate is useful, but avoid forcing fluids beyond thirst.

Do electrolytes stop cramps?

The evidence is mixed. The AIS describes the link between sodium loss and cramps as controversial. Fatigue and pacing also play a role. If you get frequent cramps, a sports dietitian or doctor can help.

How do I know if I’m a salty sweater?

White salt lines on your hat or shirt, stinging eyes from sweat or a salty taste on your skin are common clues. These suggest a sodium-containing drink or salty food may help in long, hot sessions.

Sources

1. National Academies of Sciences, Engineering, and Medicine. Report sets dietary intake levels for water, salt and potassium (2004).
2. American College of Sports Medicine. Position stand: Exercise and fluid replacement. Med Sci Sports Exerc, 2007.
3. Hew-Butler T, et al. Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, 2015. Clin J Sport Med.
4. Australian Institute of Sport. Sports supplement fact sheet: Electrolytes.
5. NSW Health. Urine colour chart.
6. Mayo Clinic. Water: How much should you drink every day?

This article is for general education and is not medical advice. Check with your doctor before starting a new training or nutrition plan, especially if you have a health condition.