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.
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.
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.
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).