The Core Difference: Fuel vs. Hydration
At their most basic, running gels are designed to provide a quick and convenient source of carbohydrates to replenish muscle glycogen stores, especially during prolonged endurance exercise. This is their primary function, as our bodies' glycogen reserves are typically sufficient for about 90 to 120 minutes of high-intensity activity before depletion begins. A gel delivers a potent dose of fast-acting sugar to combat fatigue, often referred to as 'hitting the wall'.
However, because they are so concentrated, traditional energy gels lack the fluid needed for digestion. When consumed without water, the body pulls existing fluid from your system into the stomach to help absorb the dense carbohydrates. This process actively worsens your hydration status, leading to potential gastrointestinal issues like cramping, bloating, and nausea, particularly in hot conditions. Therefore, viewing a gel as a source of hydration is a fundamental misunderstanding of its purpose and mechanism.
Understanding Different Types of Running Gels
Traditional Gels
These are the thick, concentrated gels that were among the first on the market. Their key purpose is to deliver the maximum amount of carbohydrates in the smallest, most portable package. Due to their high concentration of carbohydrates, they absolutely require water to be taken alongside them. Without sufficient fluid, your body cannot efficiently digest the sugars, and you risk a rapid decline in your hydration levels. For every 20-25g of carbohydrates consumed from a traditional gel, experts often recommend pairing it with at least 250ml of water.
Isotonic Gels
Isotonic gels are a later innovation developed to address the water requirement of traditional gels. They have a thinner, more liquid consistency because they are pre-mixed with water and electrolytes. The term 'isotonic' means they have a similar concentration to your body's fluids, allowing for easier and faster absorption without needing extra water at the exact moment of consumption. However, this convenience does not mean they are a complete hydration solution. While they offer a balance of energy and rehydration, they do not replace your overall fluid needs during a long run, and you should still be drinking water consistently.
The Role of Electrolytes in Gels
Many running gels, both traditional and isotonic, contain added electrolytes like sodium, potassium, and magnesium. These minerals are essential for muscle function and nerve signaling and are lost in sweat. Replenishing electrolytes can support hydration by helping the body retain fluid and reducing the risk of cramping. However, the electrolyte content in a single gel is minimal compared to the total amount lost during a long, sweaty run. For those sweating heavily, relying solely on gels for electrolyte replacement is insufficient; a combination with electrolyte drinks or salt tablets is often necessary.
The Proper Way to Combine Gels and Hydration
To use energy gels effectively without compromising your hydration, follow these best practices:
- Pair with water: Always chase a traditional energy gel with plain water to aid absorption and avoid stomach upset. This is a non-negotiable rule for concentrated gels.
- Time it right: Take your gels at regular intervals, typically every 45-60 minutes into your run, and preferably before a water station if on a race. Starting early helps your body process the fuel before it's under great duress.
- Test in training: Never try a new gel or fuelling strategy on race day. Practice using gels in training to see how your stomach reacts and to train your digestive system.
- Avoid combining with sports drinks: Do not consume a gel alongside a high-carb sports drink. The combination can lead to an excess of concentrated sugar, increasing the risk of gastrointestinal distress and dehydration. Stick to plain water with gels.
- Don't overdo it: The body has a limit to how many carbohydrates it can absorb per hour. Overconsuming gels can lead to a sugar crash and stomach issues. Stick to recommended intervals.
Comparison Table: Gels vs. Drinks
| Feature | Traditional Energy Gels | Isotonic Energy Gels | Sports Drinks |
|---|---|---|---|
| Primary Purpose | Compact Carbohydrate Energy | Energy with Hydration Support | Hydration with Carbohydrate Energy |
| Concentration | Very High | Isotonic (matches body's fluid) | Isotonic or Hypotonic |
| Water Needed? | Yes, always to prevent dehydration | Not immediately, but overall fluid intake is vital | No, formulated to provide fluid |
| Electrolytes | Varies, often included | Yes, pre-mixed with fluid | Yes, main component with water |
| Portability | Excellent (small sachets) | Good (larger sachets) | Poor (requires bottle/flask) |
| Use Case | Best for races with aid stations providing water, or when carrying fluids separately | Convenient for runs where carrying extra water with the gel is difficult | Better for longer sessions, ultramarathons, or during warm weather when fluid loss is high |
The Final Verdict
So, do running gels keep you hydrated? The answer is a clear no, with a nuanced exception for isotonic gels. No energy gel, regardless of its type, serves as a complete replacement for proper fluid and electrolyte intake. Traditional gels, in fact, can actively cause dehydration if not paired with sufficient water. Isotonic gels offer a more fluid-friendly alternative but only supplement, not solve, your hydration needs. A successful fuelling strategy, therefore, is a combination of taking in carbohydrates from gels and consistently drinking plain water throughout your run to maintain peak performance and avoid any hydration issues.
Conclusion
Ultimately, running gels are a powerful tool for energy management during long runs and races, but they are not a substitute for water. Understanding the difference between traditional and isotonic gels is crucial for effective use. Remember that a successful endurance effort relies on a balanced approach: using gels for fuel while simultaneously prioritizing your hydration strategy by drinking plenty of water. Training your gut with this dual approach will ensure you get the maximum benefit from your fuel without risking dehydration.
For more expert advice on combining your energy and hydration intake, check out this guide from Runner's World.
