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Ted Munson

Performance Nutritionist

The worlds first Isotonic Energy Gel

Why Isotonic Energy Gels should matter to you.

GO Isotonic Energy Gel

  • The world's first isotonic gel
  • Provides a quicker supply of energy to the working muscles than a thicker, more concentrated gel
  • Clean taste and designed to be absorbed without needing additional water
  • Easily digestible and light on the stomach

What does isotonic mean?

The tonicity of a solution refers to the concentration that affects water and carbohydrate transportation across cell membranes, most importantly the movement from the gut into the bloodstream. Ultimately this will affect how quickly the gel can be used as an energy source.

Hypertonic: If a solution is hypertonic, it has a higher concentration than the fluid in the body. This means that water particles will have to be pulled from the cells into the gut to help it absorb and balance up this concentration. This slows down the availability of the energy from the gel and can bloat your stomach and be very uncomfortable.

Hypotonic: If a solution is hypotonic, it will have a lower concentration than the fluid in the body. This means that it will empty quickly from the stomach, but it will not contain much energy.

Isotonic: To be isotonic a solution must have the same concentration of dissolved particles as the fluid in the cells within the body, typically this means having a tonicity between 280-310 mmol/kg.

The carbohydrate source in GO Isotonic Energy gels is maltodextrin which we specially select. We use one with a particular size of molecule, known as its’ molecular weight. This allows us to balance the amount of energy delivered versus how quickly it empties from the stomach. This means that you will feel the performance benefits of taking on a GO Isotonic Energy gel far more quickly than when a non-isotonic gel is consumed. The risk of upsetting your stomach is also much less. Energy gels with an osmolality close to the gastric content (i.e. isotonic) may promote high carbohydrate delivery to the small intestine compared to thick, concentrated hypertonic gels (1).


What does the research say?

A published study in the International Journal of Sports Nutrition & Exercise Metabolism compared a large range of gels that are currently available on the market (31 gels from 23 brands). It showed that there are huge variances in the concentration of gels across the market, and that the GO Isotonic Energy Gel was the only isotonic gel tested (2).

The variations in energy density, carbohydrate content and source reflect the osmolality/ concentration of each gel. It is clear that the majority of sports gels (when consumed with insufficient water intake) are not aligned with promoting gastric emptying and optimum carbohydrate delivery (1). Compared to the Isotonic Energy Gel, 70% of the gels sampled were >2000 mmol/kg. Such osmolality values would not facilitate rapid gastric emptying and carbohydrate delivery to the small intestine (1).


Evidence suggests that delivering carbohydrate in the form of gels (especially when isotonic in nature) in combination with consuming electrolyte-containing fluids (like that in GO Hydro and GO Electrolyte) allows for a more flexible approach to achieving both energy and hydration goals during exercise, helping to maintain endurance performance (3).


Learn more about GO Isotonic Energy Gels in this video featuring Team Sky's Head of Nutrition - Dr James Morton.



Related Articles:



  1. Vist, G. E., & Maughan, R. J. (1995). The effect of osmolality and carbohydrate content on the rate of gastric emptying of liquids in man. The Journal of Physiology, 486(2), 523.
  2. Zhang, X., O’Kennedy, N., & Morton, J. P. (2015). Extreme variation of nutritional composition and osmolality of commercially available carbohydrate energy gels. International Journal of Sport Nutrition and Exercise Metabolism, 25(5), 504-509.
  3. Lee, M. J. C., Hammond, K. M., Vasdev, A., Poole, K. L., Impey, S. G., Close, G. L., & Morton, J. P. (2014). Self-selecting fluid intake while maintaining high carbohydrate availability does not impair half-marathon performance. International Journal of Sports Medicine, 35(14), 1216-1222.


  • Isotonic Gel
    Ian Cooper commented on June 29, 2016 at 2:14 pm

    Been cycling 56 years and never taken any notice of science in sport until the last couple of years. I now warm up, warm down, do the recommended stretching after a ride, have a recovery drink, and go to the gym to strengthen my core. Now in retirement cycling throughout the year and keeping up with the "young ones"

  • Were can i buy them?
    Gary Rodgers commented on July 3, 2016 at 6:20 am

    I'm a keen fairweather cyclist and go on an average 30 to 40mile cycle tour generally to keep fit however I have never tried isotonic gel ever but after seeing the sky team promotional video I can't want to give them a try I'm 54 and just love the freedom of being on a bike but all tips are very welcome thanks team Sky I will let you know how they preformed thanks again

  • Excellent
    Jorge Garcia commented on July 12, 2016 at 1:55 am

    This is by far the best energy gel I have used, and continue to use for my ongoing running and cycling training. Aware of my body and its needs as I progress through long runs and rides, I can feel the energy kick through my aching body almost immediately after I consume the SiS Isotonic gel. Bravo on the flavours too. Thanks SiS and go team SKY!

  • isotonic gel
    Anthony Clarke commented on July 14, 2016 at 5:45 pm

    Great gel love it all ready claimed free gift

  • Back to it
    Scott commented on July 15, 2016 at 3:05 am

    Can't wait to try new stuff and back on my bike

  • Great gels
    Ian commented on July 30, 2016 at 3:18 am

    I Always use these sis gels. They do actually work and they say always eat bars / flapjacks before you feel hungary on the bike. You will perform much better taking these gels but i also take the sis tabs drinks with me. 2 bottles. Hydrate on the go is key to be at your best.

  • 12 FREE GELS
    Susan Johnson commented on August 4, 2016 at 3:58 pm

    Filled out for the offer today and I can't wait till they send me the code.

  • Looking forward to trying
    Shelly commented on August 4, 2016 at 7:48 pm

    Hopefully it will help me with my exercises I need lots of energy!!!

  • Looking forward to trying these!
    Diana commented on August 5, 2016 at 9:17 am

    excited to try these out!

  • walker
    patty Hatfield commented on August 5, 2016 at 3:00 pm

    I am looking forward to trying them out

    Anne Tapp commented on August 5, 2016 at 5:59 pm


  • Energia pura
    Ana hernandez commented on August 6, 2016 at 9:35 am

    Lo mejor para mantenerme activo y llena energia

  • Thanks
    Gabriela Toledo commented on August 6, 2016 at 11:40 am

    Great gel love ir all ready claimed free,Thanks

  • exelent
    margarita commented on August 6, 2016 at 1:21 pm

    Is product exelwnt

  • 13 Half Marathons
    Ken commented on August 8, 2016 at 12:06 pm

    Looking forward to receiving these. The other gels upset my stomach. Running 13 half sin 13 months and trying to find a product that will work for me. Will let you know what I think!!

  • Me gustaria probar el producto
    Juana commented on August 8, 2016 at 9:55 pm

    Me gustaria probar el producto

  • Need something new.
    Eric Schweighauser commented on August 14, 2016 at 10:24 am

    I'm looking forward to trying these new gels when I go mountain biking. Other brands have left a sour after taste.

  • great
    emma commented on September 11, 2016 at 5:45 pm

    I have used these gels from the start. They are perfect for my needs. Great taste and great performance. I'm about to embark on my 35th marathon. Ironman 140.6 training going g well too ?

  • Diabetic
    Daniel Elliott commented on September 12, 2016 at 2:34 pm

    Hi, please can you tell me if SIS gels are safe for type 2 diabetics

  • In need of the extra energy !!
    Kerry McAlees commented on September 19, 2016 at 11:18 am

    I'm looking forward to trying these. I've seen them for sale but have never tried them as I never know if there is a right one for me, now that I have upped my exercise regime with 1 - 2hrs in the gym every week as well as 3x 1hr sessions of pole fitness, 2x 45min sessions of LBT's, 1x 1hr session of circuits training, 1x 1hr session of body pump and a 30min swim every week I also cycle to most of my classes which are only about 4 miles away but it all counts lol. Really thinking of taking some with me on my ten mile charity obstacle run next year as I was flagging quite a lot after a bag of haribo and 3 energy drinks had worn off !!

  • I would like to try gels
    Brenda commented on June 8, 2017 at 5:51 am

    Interested in gels for running

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