When to Use SiS Energy Gels for Peak Performance

December 4, 2025 •

4 min read

Endurance athletes' muscles can only store enough glycogen for about 90 minutes of exercise, making mid-effort fueling critical for maintaining performance. Knowing when to use SiS energy gels is a key part of preventing the dreaded 'bonk' and sustaining your pace during long or intense sessions.

Quick Summary

Guide to the ideal timing and strategy for consuming SiS energy gels based on exercise duration and intensity. Outlines the different gel types and their specific use cases for optimal performance and digestion.

Key Points

Timing is key: Consume SiS gels at regular, planned intervals during prolonged exercise, not waiting until you feel exhausted.
Isotonic Advantage: SiS gels are isotonic, meaning they absorb quickly without extra water, minimizing bloating and stomach issues.
Use variety: Switch between different SiS gel types like isotonic, caffeinated, and electrolyte options based on the stage and conditions of your race.
Endurance Fueling: For events over 90 minutes, start with a gel at 20-30 minutes and continue every 20-30 minutes to maintain energy.
Caffeine for a Boost: Save caffeinated gels for the later stages of a race or a tough climb to increase focus and combat fatigue.
Hydration Matters: Although SiS isotonic gels don't require water with consumption, proper hydration with water or an electrolyte drink is still critical.
Train with your Gels: Always practice your race-day fueling plan during training to ensure your body tolerates the gels well.
Consider Beta Fuel for Ultra-Endurance: For events over two hours, the higher carbohydrate count and 1:0.8 ratio of Beta Fuel gels provide a more efficient energy source.

Understanding the SiS Advantage: Isotonic Technology

Science in Sport (SiS) energy gels differ from many competitors due to their isotonic formula. An isotonic solution has a similar concentration of fluids, salts, and carbohydrates to the body's own fluids, which means it can be absorbed quickly without needing additional water. This reduces the risk of bloating and gastrointestinal distress often associated with thicker, more concentrated gels. While this convenience is a major benefit, it's still crucial to maintain overall hydration during your activity, which is not fully covered by the gels alone.

The Go-To Gel: SiS GO Isotonic Energy Gel

The GO Isotonic Energy Gel is the workhorse of the SiS lineup. With 22g of readily available carbohydrates, it’s designed to provide a quick and easily digestible energy supply.

For endurance events (over 90 minutes): Start fueling early, around 20 minutes into the race or training session, and continue taking one gel every 20-30 minutes. This strategy helps maintain a consistent energy level before your glycogen stores become significantly depleted.
For shorter, high-intensity sessions (under 90 minutes): Consume one gel about 15 minutes before starting your exercise for a fast-acting energy boost.

Advanced Fueling with Specialized Gels

SiS also offers a range of specialized gels to address specific athletic needs, such as mental focus and electrolyte balance.

The Mental Boost: SiS GO Energy + Caffeine Gel

For moments when you need a mental as well as a physical lift, the caffeinated gels are a great option.

Endurance athletes: Take a 75mg caffeine gel one hour before the end of your event to combat fatigue and improve focus.
High-intensity sports: A 75mg or 150mg caffeine gel taken 15-30 minutes before or at halftime can sharpen concentration. Test your caffeine tolerance in training to avoid negative side effects.

The Electrolyte Replenisher: SiS GO Energy + Electrolyte Gel

When exercising in hot conditions or during periods of heavy sweating, electrolyte loss becomes a major factor in performance.

Hot weather: Use 1-2 electrolyte gels during exercise to replace minerals like sodium and potassium lost through sweat.
Combined fueling: These can be used alongside the standard GO Isotonic gels to ensure both energy and electrolyte needs are met.

The High-Carb Option: Beta Fuel Gels

For elite and serious endurance athletes, the Beta Fuel range offers a higher carbohydrate intake.

Ultra-endurance: Designed for activities over two hours, the Beta Fuel gel provides 40g of carbohydrates from a specific maltodextrin-to-fructose ratio, allowing for enhanced carbohydrate usage. The target intake is typically 80-120g of carbs per hour, which can mean 2-3 Beta Fuel gels hourly.
Beta Fuel + Nootropics: These include nootropics to enhance mental performance and should be used strategically, such as in the final hour of a race.

SiS Gel Comparison Table


Gel Type	Carbohydrate Content	Key Feature	Best Used For	Notes
GO Isotonic	22g	Fast-acting, no water needed	General endurance events >90min	Foundational fuel, easy on the stomach.
GO + Caffeine	22g	Mental boost, improved focus	End of long events, high-intensity moments	Test tolerance; multiple dosages available.
GO + Electrolyte	22g	Replenishes lost salts	Hot conditions, heavy sweating	Use alongside isotonic gels for a balanced approach.
Beta Fuel	40g	Higher carb volume (1:0.8 ratio)	Prolonged, ultra-endurance efforts	For experienced athletes with adapted guts; aim for 80-120g/hr.

Practical Application and Strategy

Your SiS energy gel strategy should be practiced extensively during training, not just for race day. This allows your gut to adapt and helps you pinpoint the best timing and gel type for your individual needs.

Best practices include:

Start early: Begin fueling 15-20 minutes into an intense session or 20-30 minutes into a long event. Don't wait until you feel drained.
Set reminders: Use a watch or timer to prompt you to take gels at consistent intervals. Consistency is key for sustained energy.
Consider a mix: Combine different SiS gels within a single race. For example, use standard isotonic gels for the majority of the race and introduce a caffeinated gel for the final push.
Don't overdo it: The body has a limit to how many carbohydrates it can absorb per hour. Overconsumption can lead to stomach upset and is ineffective.
Stay hydrated: While isotonic gels don't require water to be consumed with them, it's essential to drink water regularly throughout your activity, especially when using caffeinated gels, which can be diuretic.

Conclusion: Tailor Your Strategy for Success

Understanding when to use SiS energy gels is a crucial component of any endurance athlete's nutritional plan. By recognizing the differences between the isotonic, caffeinated, electrolyte, and high-carb Beta Fuel options, you can create a tailored strategy that optimizes your performance. The isotonic nature of SiS gels makes them gentle on the stomach and easy to consume on the go. Remember to practice your fueling strategy in training to discover what works best for your body, ensuring you have the necessary energy to finish strong, whether on a long run or a challenging race..

Frequently Asked Questions

For endurance events over 90 minutes, aim to take one SiS gel every 20-30 minutes. The goal is to consume 60-90g of carbohydrates per hour, and combining with other SiS products like electrolyte drinks can help reach this target.

No, SiS GO Isotonic Energy Gels are formulated to be consumed without water, as their isotonic composition allows for quick absorption without fluid being drawn into the stomach. However, you must still maintain overall hydration separately.

Save caffeinated SiS gels for when you need a mental and physical boost. This is typically in the last hour of a race or before a particularly difficult section, like a steep climb. It's wise to test your tolerance in training first.

Yes. For intense workouts or races under 90 minutes, taking a SiS GO Isotonic Energy Gel about 15 minutes before starting can provide a rapid energy boost for maximum effect.

Beta Fuel gels are for endurance athletes participating in events lasting more than two hours. With a higher concentration of 40g of carbohydrates, they support higher hourly carbohydrate intake needs (80-120g).

You should use SiS GO Energy + Electrolyte gels when exercising in hot conditions or when sweating heavily. They replace essential minerals lost through sweat and help maintain hydration.

Yes, and you should. Practicing your race-day nutrition strategy during training is vital. It helps your body get used to absorbing the energy and prevents potential stomach issues on the big day.