Common Side Effects of Running Gels
While energy gels are an indispensable tool for many endurance athletes, providing a convenient and fast-acting source of fuel, they are not without potential downsides. For some runners, the concentrated sugar and specific ingredients can lead to uncomfortable and performance-hindering side effects. Understanding these issues is the first step toward avoiding them.
Gastrointestinal (GI) Distress
This is the most widely reported issue among runners who use energy gels. During intense exercise, blood is diverted away from the digestive system and towards the working muscles. When a high concentration of simple sugars is introduced, the body pulls water into the stomach to help with digestion and absorption. If not paired with sufficient water intake, this can overwhelm the gut, causing issues such as:
- Stomach cramps: The pulling of water into the intestines can cause painful cramping.
- Bloating and gas: Incomplete digestion or fermentation of ingredients like maltodextrin can lead to a buildup of gas.
- Nausea: This is often triggered by the high sugar content and can be compounded by dehydration.
- Diarrhea: The rapid movement of concentrated sugars through the GI tract can cause an urgent need to use the bathroom, a condition sometimes called 'runner's trots'.
Blood Sugar Fluctuations and 'Crashes'
Running gels are designed to provide a quick energy boost, and many contain simple sugars like glucose and fructose for rapid absorption. However, this can lead to a sharp spike in blood sugar levels, followed by a subsequent crash when the effects wear off. This rollercoaster of blood sugar can leave a runner feeling drained, fatigued, and sluggish, which is exactly what the gel was meant to prevent. Timing is everything, and consuming gels too frequently or without proper spacing can exacerbate this effect.
Dehydration
As noted with GI distress, the body uses water to dilute and process the concentrated carbohydrates in energy gels. If you consume a traditional gel without an adequate amount of water, it can pull existing fluid from your bloodstream into your gut, increasing your risk of dehydration. This is a particular concern when exercising in hot or humid conditions, where dehydration is already a major risk factor. Isotonic gels, which are formulated with a more balanced fluid-to-carbohydrate ratio, are designed to minimize this effect, but proper hydration remains vital with any form of concentrated fuel.
Caffeine Sensitivity and Overload
Many energy gels include caffeine to enhance performance and alertness. While a small amount can be beneficial, runners who are sensitive to caffeine may experience a variety of adverse reactions, including:
- Jitteriness or anxiety
- Increased heart rate
- Worsened GI distress, as caffeine can increase gut motility
- Sleep disturbances if consumed late in the day It is crucial to know your tolerance and to test caffeinated gels during training, not on race day.
Comparison: Traditional Gels vs. Isotonic Gels
| Feature | Traditional Energy Gels | Isotonic Energy Gels |
|---|---|---|
| Consistency | Thicker, more viscous | Thinner, more watery |
| Need for Water | Required to aid digestion and absorption | Not required for digestion, but still recommended for hydration |
| Digestion Speed | Slower absorption due to high concentration | Faster absorption due to balanced fluid content |
| Primary Risk | Higher risk of GI distress and dehydration if not paired with water | Lower risk of GI distress, but can still cause issues if over-consumed |
| Convenience | Less convenient due to needing to carry water | More convenient as they can be taken without a separate fluid |
| Best For | Runners who can manage fluid intake precisely and tolerate higher sugar loads | Runners prone to GI issues or those who prefer a less-thick consistency |
How to Avoid Side Effects
Despite the potential for side effects, you can successfully integrate running gels into your fueling strategy with a few key practices.
Train Your Gut
Your digestive system is a muscle that can be trained just like your legs. The biggest mistake runners make is trying a new gel on race day. Instead, practice your fueling strategy during long training runs. This allows your gut to adapt to processing carbohydrates during exercise and helps you identify which brands or flavors sit well with you.
Hydrate Properly
Always consume traditional energy gels with water, not another sports drink. For concentrated gels, drinking 4–6 ounces of plain water immediately after taking the gel helps to dilute the carbohydrates and aid absorption, preventing the common stomach issues. For isotonic gels, while water isn't technically required for digestion, staying hydrated is still critical for overall performance.
Experiment with Different Brands and Types
Not all gels are created equal. Some use different carbohydrate blends, like those with a specific glucose-fructose ratio, which may be easier on the stomach for some athletes. Others may use more natural ingredients, which can also reduce the risk of digestive discomfort. Explore different brands, formulas, and even alternative fuel sources like chews or sports drinks to find what works best for your body.
Don't Over-consume
Pay attention to the recommended intake frequency. Consuming gels too close together or having too many at once can overwhelm your digestive system and lead to a dramatic energy crash. Most guidelines suggest consuming 30–60 grams of carbohydrates per hour for runs over 90 minutes, with one gel typically providing around 20–35 grams.
Start Fueling Early
Don't wait until you're feeling depleted to start fueling. Begin taking your first gel 60–90 minutes into your run, and continue at regular intervals as needed. This proactive approach helps maintain steady energy levels and prevents the drastic depletion of glycogen stores, also known as 'hitting the wall'.
Conclusion
While energy gels offer a powerful and convenient way to fuel endurance running, potential side effects like gastrointestinal distress, blood sugar crashes, and dehydration are real concerns for many athletes. These issues are often tied to the high concentration of sugars, specific ingredients like maltodextrin and fructose, or the inclusion of caffeine. By training your gut, prioritizing proper hydration, and experimenting with different products, you can significantly mitigate these risks and find a fueling strategy that supports your performance without discomfort. Runners should always test new products and fueling plans during training to ensure a smooth race day experience. For runners who struggle with gels, alternatives like energy chews, sports drinks, or even whole foods can also be effective. For more detailed information on preventing GI issues during endurance exercise, a helpful resource can be found at Runner's World..
