FLYCARB Research Summary

The Ruby Paper: Carbohydrate Fuelling

Carbohydrate fuelling is one of the best-established tools for improving endurance performance. It sounds obvious, but so many of us get it wrong!

Getting your fuel right can help delay fatigue and sustain power and pace. Whether you prefer gels, drinks or a combination, the aim is simply to deliver fuel you can use, in an amount your stomach can handle (1,2).

What the Research Shows

8% Faster
Cycling Time Trial with Glucose–Fructose vs Glucose Alone (at 108g/h)
+18%
More Ingested Carbohydrate Used for Energy with a 1:0.8 vs 1:0.5 Blend
1:0.8
Optimal Glucose-to-Fructose Ratio Using Dual Gut Transport Pathways
Gel = Drink
Similar Carbohydrate Use from Gels with Water and Drinks When Matched

Why Does Carbohydrate Matter?

Your body stores carbohydrate as glycogen in the muscles and liver. During prolonged exercise, carbohydrate availability can become a limiting factor, making it harder to maintain your intended effort.

Taking carbohydrate during exercise provides another source of fuel. Back in the 80s research by Coyle et al showed that carbohydrate feeding helped trained cyclists maintain carbohydrate use and continue exercising longer, even when muscle glycogen was low (1).

Fuelling also extends beyond what you take during a race. Carbohydrate before exercise helps you start prepared, while carbohydrate afterwards helps restore stores for your next session. Ultimately, this will help you recover significantly quicker!

Why Combine Glucose and Fructose? The 1:0.8 Ratio

Glucose and fructose use different transport pathways in the gut. At high intakes, combining them allows more carbohydrate to be used for energy than relying on glucose alone. Maltodextrin provides glucose following digestion.

In a study by Currell and Jeukendrup, eight trained male cyclists completed two hours of cycling followed by a time trial. A glucose-fructose drink produced an 8% faster time trial than a glucose-only drink, with both providing 108g of carbohydrate per hour.

Another study, involving 12 male cyclists, found that a 1:0.8 glucose-to-fructose blend resulted in 18% more ingested carbohydrate being used for energy than a 1:0.5 blend. This reflects greater fuel use, rather than an 18% improvement in performance.

8% Faster
Time Trial with Glucose–Fructose vs Glucose Alone at 108g/h (Currell & Jeukendrup, 2008)
+18% Fuel Use
More Ingested Carbohydrate Oxidised with 1:0.8 vs 1:0.5 Blend (O’Brien et al., 2013)

Energy Gels or Drinks?

Both deliver fuel effectively. Research found similar carbohydrate use from gels taken with water and drinks when carbohydrate and fluid intake were matched (5). Choose whichever suits you, or combine them!

How We’ve Applied the Science: FLYGEL and HICARB

We developed FLYGEL as a simple, science-led energy gel, designed to be easy on your stomach and kind to your wallet. Each compact sachet provides 30g of carbohydrate in a 1:0.8 glucose-to-fructose ratio.

Again with a 1:0.8 ratio, HICARB is a 50g drink, perfect for building your carbohydrate intake around your training and racing. For example:

  • 60g per hour: two FLYGELs.
  • 80g per hour: one FLYGEL & one HICARB.
1:0.8 Dual-Source Fuelling

FLYGEL & HICARB

Practical, stomach-friendly carbohydrate fuelling in a 1:0.8 glucose-to-fructose ratio. Use individually or combine to hit your target hourly intake.

30g Energy Gel

FLYGEL

A simple, science-led energy gel in a compact 44ml sachet, designed to be easy on your stomach and kind to your wallet.

30g Carbohydrate 1:0.8 Ratio Compact 44ml Sachet
Shop FLYGEL →
50g High-Carb Drink

HICARB

A high-carbohydrate drink mix delivering 50g of fuel per sachet in a 1:0.8 ratio. Mix with 300–500ml water to suit your training and racing.

50g Carbohydrate 1:0.8 Ratio Single-Serve Sachet
Shop HICARB →

Interesting Research

  1. Coyle et al. (1986). Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate. PubMed →
  2. Burke et al. (2011). Carbohydrates for training and competition. Guidance on carbohydrate availability and intake across exercise durations. PubMed →
  3. Currell & Jeukendrup (2008). Superior endurance performance with ingestion of multiple transportable carbohydrates. PubMed →
  4. O’Brien et al. (2013). Fructose-maltodextrin ratio governs exogenous and other CHO oxidation and performance. PubMed →
  5. Pfeiffer et al. (2010). CHO oxidation from a CHO gel compared with a drink during exercise. PubMed →
  6. Costa et al. (2017). Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance. PubMed →
  7. Jentjens et al. (2004). Oxidation of combined ingestion of glucose and fructose during exercise. PubMed →
  8. Carpenter, Brouner & Spendiff (2025). Strategic carbohydrate feeding improves performance in ketogenic trained athletes. PubMed →
  9. Carpenter, Brouner & Spendiff (2024). Case study: carbohydrate supplementation improves ultra-endurance performance in a keto-adapted individual. Journal article →