Sis Energy Gels Ireland: How to Buy, Use and Fuel Your Runs (2026)

By Ethan Brooks

Updated November 2026

Sis energy gels Ireland runners rely on are easy to find once you know what to look for, but choosing the right product and using it well takes a bit more thought. This guide walks you through the main decisions: what SiS gels contain, how to pick between standard and caffeinated versions, how to practise with them in training, and how to avoid the stomach trouble that catches out many runners on race day. By the end, you should have a clear plan for fuelling your long runs and a simple routine you can repeat on race morning.

What SiS Energy Gels Are and Why Runners Use Them

SiS, short for Science in Sport, makes carbohydrate gels designed to deliver fast-acting energy during exercise lasting longer than about 60 to 90 minutes. Most of the gels in the range are built around maltodextrin, a glucose-based carbohydrate that the gut absorbs quickly. Many SiS products also use a blend of glucose and fructose, which sports nutrition research has linked to higher total carbohydrate absorption than glucose alone. Check the label of any specific product for exact carbohydrate and sodium content, because formulations change over time.

Shopping for one? See our guide: SiS GO Energy Gels Review: Features and Performance.

For Irish runners, the practical appeal is simple. A gel is small, needs no preparation, and gives you a known dose of carbohydrate in a single packet. That matters on hilly routes around the Wicklow Mountains, on wet days in Cork, or during a half marathon where you need a predictable fuelling plan rather than guesswork.

Step 1: Work Out How Much Fuel You Actually Need

Before you buy a box, estimate how many gels your longer sessions will require. Most runners aim for roughly 30 to 60 grams of carbohydrate per hour once a run passes the 60-minute mark, though tolerance varies a lot between individuals. A typical SiS gel provides a fixed amount of carbohydrate per packet, so divide your hourly target by that figure to find your per-hour gel count.

1. Find the carbohydrate per gel on the packaging or the manufacturer’s product sheet.
2. Choose an hourly target. Start near the lower end of the range (around 30 g per hour) if you are new to gels.
3. Divide the target by the carbohydrate per gel to get gels per hour.
4. Multiply by the number of hours in your longest planned session to get your total for the cycle.
5. Add a small buffer, usually one extra gel, in case you drop one or want to adjust on race day.

Step 2: Choose the Right Gel for Your Race or Training Block

SiS offers gels in several flavours and formats, and some contain caffeine. Pick based on how your stomach reacts and when in the day you plan to take them. Caffeine can help some runners feel sharper late in a long run, but it can also cause jitters, nausea or sleep problems if you are not used to it. Test any caffeinated version in training before you rely on it.

Flavour matters more than many runners expect. A gel you find palatable at mile 14 is worth far more than a theoretically better one you cannot face. Buy a small variety pack first, try two or three flavours on your long runs, and settle on the one you can take without effort. For a broader look at how the range differs, see SiS Energy Gels Variety Pack Review: Pros and Cons and 7 Best SiS Energy Gels for Running: Our Picks Compared.

Standard vs Caffeinated Gels

Standard gels suit most runners for training and for distances up to a half marathon when you have eaten a reasonable pre-run meal. Caffeinated versions are often considered by runners in the later stages of a marathon. If you are weighing that choice, SiS GO Energy + Caffeine Gel Review: Sis Energy Gels Caffeine Pros and Cons covers the trade-offs in more detail.

Electrolyte and Hydration Considerations

On warm or humid days, sweat losses rise and sodium becomes more important. Some runners prefer an electrolyte-containing gel, or they pair plain gels with a separate electrolyte drink. The guide Sis Go Energy Electrolyte Gels 20 Pack: A Practical Guide (2026) explains how these options fit into a fuelling plan.

Step 3: Practise in Training Before Race Day

Never try a new gel for the first time in a race. Your gut adapts to fuel with practice, and the stomach response to a gel can differ depending on how hard you are running, how you hydrated and what you ate beforehand. Use your long runs as rehearsals. Take the exact gel, at the exact interval, with the exact amount of water you plan to use on race day.

Good training practice looks like this:

• Take your first gel roughly 40 to 60 minutes into the run, not at the very start.
• Repeat at the same interval for the rest of the session, keeping notes on how you feel.
• Take each gel with about 100 to 150 ml of water, or with a sports drink if your plan includes one, unless the packaging advises otherwise.
• Increase total gels across the training block gradually, rather than jumping straight to race-day quantities.
• Repeat the full race-day routine at least two or three times before the event.

Step 4: Plan Your Timing on Race Day

Race-day timing depends on distance and pace. For a half marathon, many runners take one gel in the second half of the race and sometimes one just before the start. For a marathon, a regular interval of about every 40 to 45 minutes is common. Set a timer or use a watch alert so you do not rely on memory when your pace is falling apart. For specific timing guidance by distance, see When to Take Energy Gels During Half Marathon: A Step-by-Step Timing Guide and When to Take Energy Gels: A Marathoner's Timing Guide.

Pre-Race Meal and Gel Pairing

Eat a familiar, carbohydrate-rich meal two to three hours before the start, and keep fat and fibre low if your stomach is sensitive. Avoid a new gel in the hour before the start, since taking it too close to the gun can cause sloshing or cramping once the race begins.

Common Mistakes to Avoid

• Trying a new gel on race day. Always test in training first.
• Taking gels without water. Gels are concentrated, and without fluid they can cause stomach upset.
• Taking them too late. Waiting until you feel flat means the energy arrives after you need it most.
• Stacking caffeine. Combining caffeinated gels with coffee or energy drinks can push intake too high.
• Ignoring storage. Heat in a car boot or a hot race-day bag can change texture and make gels hard to squeeze.
• Carrying too many flavours at once. Stick with one or two you have tested to keep things simple.

Tips for Buying and Storing SiS Gels in Ireland

Stock levels for specific flavours and formats vary between retailers, so buy a few spares of anything you rely on. Store gels in a cool, dry place, away from direct sunlight, and check best-before dates before a long training block. If you are planning a half or full marathon, ordering a couple of weeks ahead gives you time to swap flavours if one does not suit you.

Recommended gear

These items support the fuelling plan described above.

• Running belt with gel pockets: a belt with small zipped or elasticated gel loops keeps packets secure and within reach, so you do not need to fumble at a feed station. View on Amazon
• Soft flask for gel and water: a squeezable handheld flask lets you wash down gels without carrying a heavy bottle. View on Amazon
• Gel tracking pocket organiser: a small waterproof pouch helps you keep training gels separate from race gels and track how many you have used. View on Amazon

FAQ

Where can I buy sis energy gels Ireland runners use?

SiS gels are typically stocked by running and triathlon specialists, sports nutrition retailers and some online shops that ship to Ireland. Check current stock on the retailer’s site before you order, since availability changes.

How many sis energy gels should I take in a half marathon?

Many runners take one or two gels during a half marathon, usually starting in the second half. Your exact number depends on pace, body weight and how much you have eaten beforehand, so test your plan in training.

Can I take a sis energy gel without water?

You can, but it is generally better to take each gel with water to help absorption and reduce stomach discomfort. Follow the packaging guidance and practise your method in training.

Are caffeinated gels safe for everyone?

Caffeine affects people differently. Those who are sensitive to it, pregnant, or managing heart or blood pressure conditions should speak with a doctor before using caffeinated products. Always test caffeine in training first.

How long before a race should I take my first gel?

Most runners take a gel roughly 40 to 60 minutes into a run or race, rather than immediately before the start. A gel just before the gun can cause stomach problems once you start moving.

Do I need electrolytes with sis energy gels?

It depends on sweat rate, temperature and race length. Some runners add electrolytes on warm or long runs, either through an electrolyte gel or a separate drink. Monitor how you feel and adjust in training.

What should I do if a gel upsets my stomach?

Stop taking that gel, drink water and switch to a different flavour or brand you have tested. If stomach problems are frequent or severe, consult a doctor or a sports dietitian for personalised advice.

How should I store gels before a race?

Keep them in a cool, dry place out of direct sun. Avoid leaving them in a hot car, since heat can soften the gel and make packets harder to open and squeeze.

Conclusion

Using sis energy gels Ireland runners can count on comes down to a clear plan: estimate your hourly carbohydrate needs, choose a flavour and caffeine level you tolerate, and rehearse the exact routine in training. Time your intake at regular intervals, take each gel with water, and avoid trying anything new on race day. With these steps in place, you can focus on running rather than wondering whether your fuel will hold up.

About Ethan Brooks

Ethan Brooks is part of our editorial team and reviews and edits our marathon & half-marathon guides, checking product details against manufacturer specifications and owner feedback.