That dreaded “bonk” is when your body runs out of quick-access fuel, and suddenly you’re shuffling along, wondering if you’ll ever see the finish line.
Sports drinks are great for replacing electrolytes and keeping you hydrated, while energy gels pack a fast, concentrated carb punch. But which one’s right for you? Honestly, it depends. How long are you running? Does your stomach rebel at certain fuels? Sometimes, it comes down to what you can actually tolerate mid-stride.
I’ve spent years testing both—sometimes with great results, sometimes with, well, less than ideal outcomes. Let’s dig into the science behind these fueling options and figure out what might actually help you hit your goals.
Breaking Down Mid-Run Fuel: Energy Gels vs Sports Drinks
Both gels and sports drinks provide carbs for your muscles when you’re out there for the long haul. The real differences are in how your body absorbs them and how practical they are while you’re on the move.
Carbohydrate Delivery and Energy Availability
Energy gels cram about 20-30g of carbs into a little packet. It’s basically sugar you can use right away.
Sports drinks give you about 15-20g of carbs per 500ml, but the carbs are diluted, which can be easier on the gut for some folks.
Common carb sources:
- Gels: Maltodextrin, fructose, glucose
- Sports drinks: Sucrose, glucose, fructose
In my experience, both get you energy pretty quickly—usually within 15-20 minutes.
Sports drinks have the bonus of extra fluid, so you’re tackling energy and hydration at once. That’s a big deal in a marathon when both tanks are running low.
Key Differences in Composition and Absorption
Gels are thick and super concentrated. You really need to chase them with water, but honestly, a lot of runners forget that when racing.
Sports drinks? Already diluted, so your stomach doesn’t have to work overtime.
Absorption quick facts:
- Gels need to be diluted in your stomach first
- Sports drinks hit your bloodstream a bit faster
One study found that 78% of athletes had stomach problems with gels. For sports drinks? Zero reported issues in that same group.
Sports drinks also help replace lost electrolytes. Most gels barely have any, unless you buy the special endurance versions.
Practical Use During Marathons and Long Runs
Gels are easy to carry. I can toss four or five in a running belt and not even notice them.
Sports drinks, though, mean carrying bottles or counting on aid stations. That’s fine if your race is well supported, but it’s not always convenient.
Quick rundown:
- Gels: Lightweight, tidy, no mixing
- Sports drinks: Heavier, need a bottle or cup
For training, I usually go with sports drinks so I can sip as I go. On race day, gels give me more flexibility—I can take one exactly when I need it.
Some runners mix things up: drinks early on, then gels later when they want a more targeted carb boost.
Who Should Use What? Expert Guidance for Endurance Athletes
Your best choice depends on a bunch of things: how sensitive your stomach is, the event distance, the weather, and honestly, what you like. Sports nutritionists will tell you there’s no universal answer.
Advice from a Sports Nutritionist and Running Coach
I’ve coached a lot of endurance athletes, and if there’s one thing I’ve learned, it’s this: There’s no one-size-fits-all solution.
If your stomach is fussy, start with sports drinks. In one study, 7 out of 9 triathletes had stomach issues with gels, but none with drinks.
Beginners? Go with sports drinks for your first few races. They’re just easier to handle.
More experienced runners can try gels once they’ve got hydration dialed in. Gels can be a game-changer if you know how your body reacts.
A lot of marathoners use drinks for the first half, then switch to gels for a late-race pick-me-up.
Cyclists tend to love gels since you can eat them on the move—no need to stop or fumble with bottles.
One big rule: Don’t try new fuel on race day. Practice during your long runs so you know what works (and what doesn’t).
Tailoring Fuel Choices by Distance and Intensity
Different events need different strategies. Here’s what I’ve seen work:
5K to 10K: Skip the fuel. You’ve got enough stored carbs for these.
Half marathon: Sports drinks are usually enough. Maybe one gel at mile 8 or 9 if you’re fading.
Marathon: Use both. Start with drinks, add gels from mile 16 on. Aim for 30-60g carbs each hour.
Ultras: Mix it up. Gels, drinks, real food—variety helps when your stomach gets picky.
Hot days: Lean on sports drinks. You’ll need the extra fluids for all that sweating.
Cool weather: Gels become more appealing. You might not want to drink as much.
Going hard: Sports drinks are easier to absorb when you’re pushing your limits.
Steady pace: Either works. Choose what’s easiest and what you actually like.
Common Pitfalls and Tips for Personalisation
Probably the most common mistake? Taking gels without enough water. You’ll want 250ml water per 20g gel carbs—otherwise, things can get rough on your gut.
A lot of athletes wait too long to start fueling. Don’t hold off until you’re feeling tired—begin taking in energy after about 45-60 minutes.
Brand switching mid-race is a recipe for disaster. Stick with what you’ve actually practised in training.
Some gels have super high osmolality, which just means they pull water into your gut and can leave you bloated or cramping. It’s worth hunting down gels with lower concentrations if that’s ever been an issue for you.
Personalisation tips:
- Try out different brands during training—don’t just grab whatever’s free at the expo
- Notice which flavours you can actually stand late in a race (it matters more than you’d think)
- Play with your timing—every 15-20 minutes is a good starting point, but see what feels right
- Save caffeinated gels for the final third of long events—they hit harder when you need it most
If your stomach’s a bit sensitive, the 6-9% carbohydrate rule might help: that’s 60-90g carbs per litre of fluid.
Keep a training diary. Jot down the weather, your effort, and how you felt. It’s not glamorous, but this kind of info actually helps you dial in your fueling for race day.
