Athlete hydration sets targets by body weight and sweat rate to keep losses under 2% and restore 1.25–1.5 L per kg lost after training.
Pre-Exercise
During
After
Short Session (<60 Min)
- Start euhydrated
- Water only is fine
- Small sips by thirst
Water OK
Long/Hot (60–120 Min)
- 0.4–0.8 L/h
- 30–60 g carbs per h
- 200–500 mg sodium per h
Mix Drink + Water
Ultra Or Heat (2+ H)
- 0.6–1.0 L/h cap
- 60–90 g carbs per h
- 500–1000 mg sodium per h
Electrolytes Heavy
Hydration For Athletes: Daily Targets And Timing
Great training days start with smart prep, steady sipping while you work, and full recovery after. The goal is simple: keep body mass change within ±2% during sessions and replace what you lose by day’s end. You’ll do that by pairing body weight math with a one‑hour sweat check.
| Timing | How Much | Why/Notes |
|---|---|---|
| 2–4 Hours Pre | 5–7 mL per kg body weight | Arrive euhydrated; add 3–5 mL/kg about 2 h pre if urine is dark |
| 10–20 Min Pre | Small top‑off (150–300 mL) | Useful if access to drinks will be limited |
| <60 Min Session | Sip to thirst | Most athletes can rely on water; keep losses ≤2% |
| 60–150 Min Session | 0.4–0.8 L per hour | Split into 2–4 sips each 15–20 min |
| 2+ Hours Or Heat | 0.6–1.0 L per hour | Use a carb‑electrolyte drink; include sodium |
| During (Fuel) | 30–60 g carbs per hour | For 1–2.5 h efforts; helps maintain pace |
| During (Fuel, Long) | 60–90 g carbs per hour | For 2.5+ h; use mixed sugars for comfort |
| Post‑Exercise | 1.25–1.5 L per kg lost | Replace within 2–4 h with sodium‑containing fluids |
| Upper Limit | Keep intake ≤ sweat rate | Overdrinking raises hyponatremia risk |
Pre‑Exercise: Start Topped Off
Use the 5–7 mL/kg range two to four hours before you train. That’s 350–490 mL for a 70 kg athlete. If urine stays dark and output is low, add 3–5 mL/kg about two hours before the start. Salt your meals. Plain water works here; the meal adds electrolytes that help you hold onto the fluid.
During Exercise: Match, Don’t Chase
Fluid needs swing with heat, pace, kit, and your personal sweat rate. A practical band is 0.4–0.8 L per hour for most sessions that last longer than an hour. Larger, faster, and heat‑acclimated athletes may sit at the high end. Smaller or cooler‑weather athletes may need less. The safest cap is your measured sweat rate.
How To Pace Sips
Split hourly targets into steady drink breaks. A plan of 150–200 mL every 15–20 minutes is common when chasing 0.6–0.8 L per hour. If the bottle is your only fuel, fold in carbohydrate and sodium so you can check two boxes at once.
When To Use A Sports Drink
Water covers short, cool sessions. Add a carb‑electrolyte drink when effort runs past an hour, sweat is salty, or heat ramps up. Drinks that contain 4–8% carbohydrate with sodium land well for most athletes. If a mix feels heavy, drop the strength and add gels or chews for carbs.
After Exercise: Rehydrate Right
Weigh in, towel off, then weigh again. Multiply the loss by 1.25–1.5 L per kilogram. That premium covers continued sweating and urine losses in the next few hours. Include sodium in food or drink to speed retention. If there’s a long gap before the next session, normal meals and steady fluids can do the job.
Find Your Sweat Rate In One Hour
Set up a simple field test on a day that matches your usual conditions. Use the same shoes and kit. Bring a known‑volume bottle and a towel. This test gives you a per‑hour number that’s easy to use during any sport.
- Weigh before training (light kit, dry skin).
- Train for 60 minutes. Track how much you drink. Skip bathroom breaks if you can.
- Towel off and weigh again right away.
- Use the formula: sweat rate = (pre‑weight − post‑weight) + drink volume − urine. Convert kilograms to liters (1 kg ≈ 1 L).
That number becomes your hourly target across similar days. It also sets your per‑break sip size. If a session offers four breaks per hour, divide your hourly need by four. If you’re chasing speed, practice with the same bottles you’ll use on the course.
| Step | What To Note | Example (70 kg, 60 min) |
|---|---|---|
| 1. Pre‑weight | Body mass before training | 70.0 kg |
| 2. Post‑weight | Body mass after training | 69.1 kg |
| 3. Drink Volume | Total fluid taken during session | 0.4 L |
| 4. Urine | If any, measure or estimate | 0.0 L |
| 5. Sweat Rate | (Step 1 − Step 2) + Step 3 − Step 4 | 1.3 L/h |
| 6. Per‑Break Sip | Divide sweat rate by breaks per hour | ~325 mL if 4 breaks |
| 7. Post‑Exercise Plan | 1.25–1.5 L per kg lost | 1.1–1.4 L in next 2–4 h |
Electrolytes That Matter
Sodium: The Anchor
Heavy sweaters lose a lot of sodium. A sports drink with 460–1150 mg sodium per liter pairs well with long or hot work. Some athletes prefer salty foods instead. Either way, include sodium when sessions run long or when your shirt shows white streaks. For big sweaters, a target of 300–600 mg sodium per hour keeps intake near common sweat losses.
Carbohydrates: Fuel That Carries Fluid
Carb intake supports pace and helps you absorb fluid. A range of 30–60 g per hour suits efforts up to about 2.5 hours. Longer days favor 60–90 g per hour using mixed sugars like glucose and fructose. Gels, chews, soft bars, and drink mixes all fit. Practice the menu at training pace to avoid gut surprises.
Caffeine: Friend, Not Foe
Small to moderate caffeine doses around 1–3 mg per kg before or during training can aid alertness and perceived effort. In habitual users, this intake doesn’t dehydrate you or prevent you from meeting fluid goals. If you’re sensitive, shift the dose earlier in the day or skip it.
Hydration Plans By Sport
Endurance Running
Use the hourly number from your sweat test and the course map to plan breaks. Many runners do well carrying a soft flask and refilling at aid. For half‑marathon pace, 0.4–0.6 L per hour is common on a mild day; hot races push some runners closer to 0.8–1.0 L per hour. Keep an eye on body mass changes at the finish.
Field And Court Sports
Access to drinks comes in bursts. Set a per‑break target, then keep the bottle where you stand between plays. For a 1.0 L/h need with four stoppages each hour, sip ~250 mL each time. If cramps tend to show up late, check if total intake is short and whether sodium is low.
Strength, Power, And Cross‑Training
Short bouts in the gym demand less fluid. Bring a bottle and take a few mouthfuls between sets. On long circuits or steamy boxes, you may still reach 0.4 L per hour. Chalky hands love a bottle with a flip‑top so you can drink without a mess.
Cycling And Swimming
Cycling makes drinking easy. Mount two bottles for long rides, and refill at stops. A common setup is water in one cage and a light sports drink in the other. Pool sessions are cooler, yet dry air and hard repeats still move sweat. Keep a bottle at lane rope height and sip at wall breaks.
Red Flags And Fixes
Warning signs of falling behind include sticky mouth, rising heart rate, chills in heat, and fading pace. Signs of overdoing it include swollen fingers, tight rings, sloshing gut, or weight gain across a session. If confusion or vomiting shows up after long work, stop and get urgent care.
- Weigh before and after key sessions; keep change within −2% to +1%.
- Don’t pound large amounts at once; spread intake across breaks.
- Use sodium on long or hot days; aim higher if you’re a salty sweater.
- Cap intake around your sweat rate; avoid routine drinking above 1.0 L/h without measured need.
Simple Starter Plan
Morning Session
Wake, drink a glass with breakfast, then sip coffee or tea if you like. Two hours pre‑session take 5–7 mL per kg of body weight. Ten minutes before the warm‑up, finish a small top‑off. During, aim at your hourly target split into even sips each 15–20 minutes. After, replace 1.25–1.5 L per kilogram lost with salty food or a sports drink.
Midday Or Evening Session
Eat a meal with salt two to three hours before training and drink the 5–7 mL/kg amount across that window. Carry a bottle in meetings or class so you’re not playing catch‑up. During, follow your sweat‑rate number. After, go back to your 1.25–1.5 L per kilogram lost plan, then carry on with normal meals.
Make It Personal
Hydration plans land best when they fit your build, pace, and schedule. Do a one‑hour sweat test in heat, in cold, and at race intensity. Save the numbers in your phone. Adjust for altitude trips and tight turnarounds with a teammate or coach. Bring a bottle to every session so good choices are always in reach.
You can also use the CDC sweat rate formula to double‑check your math on big training blocks. A little prep keeps you steady on the hard days and smooth on the easy ones.