Science in Sport Isotonic Energy Gel Review

Flavors options include apple, lemon lime, orange, and tropical.​

What is it?

Though still potentially unfamiliar to many U.S. endurance athletes, London-based Science in Sport (or SiS) has been around since 1992, churning out a variety of athlete fuel for before, during, and after exercise. Their top sponsored users include a couple dozen Olympic athletes and Team Sky, whose riders have captured four of the last five Tour de France general classification titles.

All SiS products are manufactured in the U.K. at the company's Innovation Centre in Lancashire, where they are Informed­Sport tested and accredited. SiS claims everything passes stringent contamination testing, meaning you don't have to worry about any adverse analytical findings after you slurp a gel or gulp some recovery drink.

In 2016, Science in Sport made a concerted push into the North American market, spearheaded by what it bills as the world's first Isotonic Energy Gel, meaning you don't need water to digest the gooey goodness. The taste (which some might call watery) is much lighter than your standard helping of on-the-fly energy. This, says SiS, makes its gels easier on the stomach, which can process the stuff faster and without the need for water, which in turn lessens the risk of bloating.

Each gel contains 22 grams of fatigue-fighting carbohydrates. Flavors options include apple, lemon lime, orange, and tropical. SiS recommends that you ingest 1-3 gels per hour during vigorous exercise.

SiS also offers a GO Energy + Caffeine Gel that includes 75mg of caffeine along with the 22g of carbs per gel. Some studies have shown that caffeine can improve performance by lowering the perception of effort because it acts as a stimulant on the brain. SiS caffeine gel flavor options are citrus and berry.

Science in Sport Isotonic Energy Gel Review

SiS has helped fuel Team Sky to numerous WorldTour race wins, including the 2016 Tour de France general classification title.​


  • Not overly sweet
  • Easy to swallow
  • Lessened risk of bloating
  • No water needed to digest
  • Tour de France proven
  • Easy to open packing
  • Great on hot days
  • Low risk of product contamination
  • 22 grams of carbohydrates per gel


  • Watery consistency compared to typical gels
  • Mild, bordering on bland flavor
  • Limited flavor options
  • Only two caffeinated flavors
  • Packet takes up more jersey space than traditional gel
  • No litter leash like some gel packs
  • $1.50 per gel adds up quick

Science in Sport Isotonic Energy Gel Review

Science in Sport has a broad product range of nutrition products for before, during, and after exercise.​

RoadBikeReview's Take

I'm probably in the minority here, but I really don't mind energy gels. Over the years I've done a handful of long-distance road and mountain bike races/rides where they the only "food" I ate was gooey. And I finished - without barfing or becoming otherwise gastrointestinally compromised.

But plenty of cyclists gag at their mere mention. And for all those people, the SiS Isotonic Energy Gel could be a godsend. These gels contain roughly the same amount of carbohydrates (22g per pack) as most of the competition, but they are easier to get down the gullet, especially on hot days where it can be harder to stay on top of on-bike nutrition. The tradeoff is the taste is definitely on the bland side, which occasionally left me missing the more intense flavor of say a chocolate Clif Shot that can be a motivating treat to get you over the top of a long climb.

The other (arguably more important) feature of the SiS gels is their isotonic make-up, which for all the non-nutritionists out there means you don't need to chase them with water to kick-start the digestion process. Instead, your stomach can handle processing all by itself. That purportedly means quicker carbohydrate absorption into the body (which could stave off a bonk), and lessened chance of liquid-induced bloating.

Science in Sport Isotonic Energy Gel Review

We've been using SiS energy gels for several months now, and have been impressed with their effectiveness.​

I personally have never had an issue with the later predicament when using regular gels, and even likened the gel-first-water-bottle-contents-second process as a way to stay on top of hydration, since I typically chase the gel with some sort of electrolyte-infused concoction. But after using the SiS gels off and on this past fall and early winter, I've grown to like their watery consistency, which is more like pulpy orange juice than sugary molasses. I've also yet to bonk while using them, which is testament that my body getting what it needs when it needs it.

The bottom line, though, will likely come down to your personal taste and texture preferences. If the standard gooeyness of traditional gels turns your stomach, then SiS Isotonic Energy Gels definitely belong in your jersey pocket or hydration pack. They're easy to get down, contain performance enhancing carbohydrates, and are absorbed quickly and easily.

Rating: 4 out of 5
4 stars

Price: $9 for pack of six (currently on sale for 50% off)
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