Ultra Runners: Hydration Strategies, Gear, and Optimization

How do ultra runners carry water?

Ultra runners primarily carry water using specialized hydration vests, handheld bottles, or waist belts, often combining methods to ensure adequate fluid intake over long distances and varied terrains, prioritizing efficiency, capacity, and comfort.

The Criticality of Hydration in Ultrarunning

Effective hydration is not merely a comfort but a fundamental physiological necessity and a cornerstone of performance and safety in ultrarunning. The extreme demands of covering vast distances, often over many hours or even days, lead to significant fluid and electrolyte losses through sweating. Failure to maintain adequate hydration can rapidly lead to dehydration, manifesting as reduced performance, muscle cramps, heat exhaustion, and in severe cases, life-threatening heatstroke or hyponatremia (low sodium levels due to overconsumption of plain water without electrolytes). Therefore, ultra runners meticulously plan their hydration strategy, selecting gear that allows them to carry sufficient fluids while minimizing discomfort and maximizing accessibility.

Primary Methods of Water Carrying

Ultra runners employ a variety of specialized gear designed for efficiency and capacity, often mixing and matching based on race specifics and personal preference.

Hydration Vests/Packs

Hydration vests are the most popular and versatile option for ultra runners, designed to distribute weight evenly across the torso.

• Description: These vests typically feature a large bladder pocket on the back (ranging from 1.5 to 3 liters) with a hose that routes over the shoulder for easy access. They also incorporate multiple pockets on the front straps for soft flasks (500ml-750ml each), gels, nutrition, phones, and other essential gear.
• Pros:
  • High Capacity: Can carry significant volumes of water and other supplies.
  • Even Weight Distribution: Minimizes bounce and reduces strain compared to other methods.
  • Hands-Free: Allows for unencumbered running, scrambling, or using poles.
  • Integrated Storage: Multiple pockets for easy access to nutrition and gear.
• Cons:
  • Bulkier: Can feel warm against the back, especially in hot conditions.
  • Bladder Cleaning: Requires diligent cleaning to prevent mold or bacterial growth.
  • Refilling Time: Bladders can be slower to refill at aid stations than bottles.
• Best Use: Long distances, remote sections between aid stations, mandatory gear requirements, or races in varied terrain.

Handheld Bottles

Handheld bottles are a simple and effective solution for shorter ultras or in conjunction with other carrying methods.

• Description: These are typically ergonomic bottles (300ml-750ml) often with a strap that fits snugly around the hand, allowing for a relaxed grip. Some incorporate small pockets for keys or gels.
• Pros:
  • Immediate Access: Water is always available without breaking stride.
  • Easy to Monitor Intake: Visual cue of fluid consumption.
  • Simple to Clean and Refill: Quick turnaround at aid stations.
  • Ventilation: No back coverage, good for hot weather.
• Cons:
  • Limited Capacity: Generally carry less fluid per bottle.
  • Arm Fatigue: Can lead to muscular imbalance or fatigue over very long durations.
  • Occupies Hands: Can be cumbersome when needing to use hands for balance, climbing, or poles.
• Best Use: Shorter, faster ultra-distances, or as supplementary hydration carried alongside a vest or belt, especially for electrolyte mixes.

Waist Belts/Packs

Waist belts offer a compromise between handhelds and vests, carrying water around the hips.

• Description: These belts typically hold one or more small bottles (150ml-500ml each) in holsters around the waist. Some larger versions are essentially small fanny packs with bottle holders and additional storage pockets.
• Pros:
  • Lower Center of Gravity: Can feel less cumbersome than a vest for some runners.
  • Good for Shorter Distances/Supportive Courses: Sufficient for courses with frequent aid stations.
  • Easy Access to Bottles: Simple to grab and replace bottles.
• Cons:
  • Bouncing: Prone to bouncing if not fitted properly or if overloaded.
  • Limited Capacity: Generally less fluid capacity than a vest.
  • Can Cause Chafing: Around the waist if not correctly positioned.
• Best Use: Marathons, shorter ultra distances, or as a secondary system for specific fluid types (e.g., plain water in the vest, electrolytes in the belt).

Collapsible Bottles/Flasks

Soft flasks are increasingly popular, especially for use in hydration vests and waist belts, but can also be handheld.

• Description: These are flexible, lightweight bottles made from TPU (thermoplastic polyurethane) that compress as you drink, eliminating sloshing and taking up less space when empty. Common sizes are 250ml, 500ml, and 750ml.
• Pros:
  • Minimal Sloshing: Compresses as fluid is consumed.
  • Lightweight and Packable: Folds down when empty.
  • Versatile: Fits in vest pockets, belt holsters, or can be handheld.
  • Easy to Refill: Wide mouth openings.
• Cons:
  • Durability: Can be punctured more easily than rigid bottles.
  • Temperature Retention: Offer minimal insulation.
• Best Use: As primary or secondary bottles in vest pockets or waist belts, and for carrying additional fluid capacity that can be easily stowed once consumed.

Factors Influencing Water Carrying Choice

Selecting the optimal hydration system depends on several critical variables specific to the race and runner.

Race Distance and Aid Station Frequency

Longer, more remote races with sparse aid stations necessitate higher carrying capacity (e.g., hydration vests with large bladders). Shorter ultras or those with frequent, well-stocked aid stations might allow for lighter setups like handhelds or smaller belts.

Environmental Conditions

Hot, humid, or high-altitude environments increase fluid loss, demanding greater carrying capacity. In such conditions, runners might opt for a larger bladder or carry additional soft flasks. Conversely, colder conditions might reduce immediate fluid needs but still require adequate hydration.

Personal Preference and Comfort

What works for one runner may not work for another. Some prefer the freedom of hands-free running with a vest, while others dislike the feeling of a pack on their back and prefer handhelds. Comfort, fit, and the absence of chafing are paramount over many hours.

Required Gear Capacity

Ultra-races often have mandatory gear lists (e.g., rain jacket, first aid kit, headlamp). The chosen hydration system must accommodate these items in addition to water and nutrition. Vests excel here due to their integrated storage.

Race Rules and Regulations

Some races have specific rules regarding the minimum fluid capacity a runner must carry at all times, especially in self-supported sections or remote areas.

Beyond Water: Electrolytes and Filtration

Hydration in ultrarunning extends beyond plain water to include electrolyte balance and, in some cases, water purification.

Electrolyte Replenishment

Sweat contains electrolytes, primarily sodium, potassium, calcium, and magnesium. Replenishing these is crucial to prevent hyponatremia and muscle cramping. Ultra runners often carry electrolyte tablets, powders, or pre-mixed drinks in separate bottles or soft flasks to supplement plain water.

Water Filtration/Purification

In very remote or self-supported ultras, runners may need to source water from natural bodies (streams, lakes). Portable water filters or purification tablets are essential tools to make questionable water sources safe for consumption, reducing the volume of water that needs to be carried from the start.

Optimizing Your Hydration Strategy

A successful hydration strategy is dynamic and personalized, evolving with experience and race-specific demands.

Practice During Training

Never try new hydration gear or strategies on race day. Test different systems, fluid types, and carrying capacities during long training runs in varied conditions to understand what works best for your body and the specific demands of your target race.

Monitor Intake and Output

Learn to listen to your body's hydration cues. Pay attention to thirst, urine color, and energy levels. While scheduled drinking is important, over-drinking plain water can be as dangerous as under-drinking, leading to hyponatremia.

Utilize Aid Stations Effectively

Aid stations are critical for refilling. Plan your fluid needs between stations. Be efficient in refilling your bottles or bladder, and take advantage of any provided electrolyte drinks or food.

Consider Dual Systems

Many ultra runners use a combination of methods, such as a hydration vest for primary water and gear, along with a handheld bottle for an electrolyte drink or a specific race section. This provides flexibility and redundancy.

Conclusion: A Personalized Approach to Ultra-Hydration

There is no single "best" way for ultra runners to carry water; rather, it is a highly personalized decision rooted in the principles of exercise physiology, biomechanics, and practical logistics. The chosen method must provide sufficient fluid capacity, integrate seamlessly with other required gear, and above all, feel comfortable and efficient for the individual runner over immense distances. By understanding the options and the factors influencing choice, ultra runners can craft a robust hydration strategy that supports their performance and ensures their safety on the trail.