Proper hydration is one of the most critical yet often misunderstood aspects of running performance and health. Getting your hydration strategy right can mean the difference between a personal best and hitting the wall, between feeling energised and struggling through every kilometre. This comprehensive guide will help you understand the science of hydration and develop strategies that work for your unique needs.
Understanding Your Body's Hydration Needs
Your body is approximately 60% water, and this fluid is essential for virtually every physiological function, from regulating temperature to transporting nutrients. When you run, your body generates significant heat that must be dissipated, primarily through sweating. This cooling mechanism is vital but comes at the cost of fluid and electrolyte loss.
The amount you sweat varies dramatically based on genetics, fitness level, running intensity, and environmental conditions. Some runners lose as little as 400ml per hour, while others may lose over two litres in hot, humid conditions. Understanding your personal sweat rate is the foundation of an effective hydration strategy.
Daily Hydration for Runners
Hydration isn't just about what you drink during a run; it's a 24-hour consideration. Starting a run well-hydrated gives you a significant advantage, as even mild dehydration before exercise can impair performance and increase perceived effort.
A general guideline is to consume approximately 30-40ml of water per kilogram of body weight daily, with additional intake for training. For a 70kg runner, this translates to roughly 2.1 to 2.8 litres of water per day, before accounting for exercise-related losses.
Monitor your urine colour as a practical hydration indicator. Pale yellow, similar to lemonade, suggests adequate hydration. Dark yellow, resembling apple juice, indicates you need to drink more. Clear urine might actually indicate overhydration, which carries its own risks.
Pre-Run Hydration Strategies
Proper pre-run hydration sets you up for success. The goal is to start your run in a well-hydrated state without feeling waterlogged or needing a toilet break mid-run.
Aim to consume 5-7ml per kilogram of body weight approximately four hours before running. This allows time for your body to absorb the fluid and for excess to be excreted before you start. For a 70kg runner, this means about 350-500ml of water.
In the hour before running, sip small amounts rather than drinking large volumes. Consuming too much fluid immediately before running can lead to stomach discomfort and sloshing sensations that distract from your run.
Hydrating During Your Run
The necessity and approach to mid-run hydration depends significantly on the duration and intensity of your run, as well as environmental conditions.
Short Runs (Under 45 Minutes)
For runs under 45 minutes in moderate conditions, most well-hydrated runners don't need to drink during the run. Your body has sufficient reserves to manage these shorter efforts without additional fluid intake.
Medium Runs (45-90 Minutes)
For runs in this range, consider carrying water, especially in warm conditions. Aim to drink small amounts regularly rather than large volumes infrequently. A general target is 150-250ml every 15-20 minutes, adjusted for your sweat rate and conditions.
Long Runs (Over 90 Minutes)
Extended runs require more strategic hydration planning. This is where hydration belts become invaluable, allowing you to carry sufficient fluid and drink according to your needs rather than relying on water fountains or having to plan routes around water sources.
The Role of Electrolytes
Sweat isn't just water; it contains essential electrolytes, particularly sodium, that must be replaced during longer efforts. Sodium losses can range from 500mg to over 2000mg per litre of sweat, depending on the individual.
For runs under an hour, plain water is typically sufficient. For longer runs, incorporating electrolytes becomes increasingly important. This can come from sports drinks, electrolyte tablets, or naturally through pre and post-run meals that include adequate salt.
Signs of electrolyte imbalance include muscle cramps, nausea, and in severe cases, confusion or disorientation. If you experience these symptoms, particularly during long runs in hot conditions, you may need to increase your electrolyte intake.
Post-Run Rehydration
Recovery begins the moment you finish running, and rehydration is a critical component. The goal is to replace the fluid and electrolytes lost during your run to restore your body to its baseline state.
Aim to consume 125-150% of your fluid losses in the hours following your run. If you lost one kilogram during your run (approximately one litre of sweat), you should consume 1.25 to 1.5 litres of fluid. This accounts for ongoing losses through sweat and urination as you recover.
Include sodium in your post-run recovery through either salted foods or electrolyte drinks. Sodium helps your body retain the fluid you consume rather than rapidly excreting it.
Hydration in Australian Conditions
Australia's climate presents unique challenges for runners. Summer temperatures regularly exceed 30 degrees Celsius across much of the country, with humidity varying from the dry heat of the outback to the tropical conditions of Queensland's coast.
In hot conditions, increase your pre-run hydration and consider starting your run with a slightly higher fluid load. Plan routes that include water fountains or opportunities to refill bottles. If possible, schedule runs for the cooler parts of the day, typically early morning or after sunset.
Common Hydration Mistakes
Understanding what not to do is just as important as knowing the right practices.
Overdrinking is a real risk, particularly for slower runners during marathons. Hyponatremia, a condition caused by consuming too much water and diluting blood sodium levels, can be life-threatening. Symptoms include bloating, nausea, and confusion.
Relying solely on thirst in extreme conditions can also be problematic. While drinking to thirst works well in moderate conditions, extreme heat or very long races may require more proactive hydration strategies. Learn your body's signals and adapt your approach accordingly.
Choosing Hydration Gear
The right hydration gear makes maintaining proper fluid intake easier and more convenient.
Handheld bottles work well for medium-length runs and runners who prefer the simplicity of a single bottle. Hydration belts distribute weight more evenly and offer greater capacity for longer runs. Hydration vests or packs are ideal for trail running and ultramarathons where significant fluid and nutrition storage is necessary.
Experiment with different options during training to find what works best for your body type, running style, and typical distances. The best hydration solution is one you'll actually use consistently.