Your homemade workout recipe: carbs, water, digestive concentration and electrolytes, calculated for your duration, the temperature, your sweat rate and your intensity.
Beyond ~60 to 75 min of exercise, your glycogen stores (your muscle fuel) run down: that's the bonk.
Expected benefit: drinking carbs + water + sodium during exercise keeps energy up and prevents cramps and nausea — you hold your intensity to the end.
42 g of carbs / h
to dissolve in 0.6 L of water (~7 % — safe digestive zone).
+ 18 g/h as gels or solids, with plain water (to stay ≤ 8 %).
Over 1 h
Off-the-shelf workout drinks impose a fixed carb/water ratio, designed for a light runner in mild weather. But your needs vary with duration, heat, your sweat rate and intensity: the same powder becomes too concentrated (digestive trouble) or too dilute (insufficient intake). Calculating carbs, water and electrolytes separately — then adjusting the concentration — gives you a recipe truly matched to your session.
The literature puts carb intake between 30 and 60 g/h, and up to 90 g/h with a multi-transportable mix (2:1 maltodextrin/fructose ratio) that saturates the intestinal transporters SGLT1 and GLUT5. The drink concentration should stay in a 6 to 8% band: beyond that, gastric emptying slows and digestive risk climbs. Sodium losses are offset with 500 to 1000 mg/h depending on sweat rate.
The key is carb concentration (% = grams per 100 mL), not the brand of powder. When your carb target exceeds what your water volume can dilute to 8%, don't force it all into the bottle: keep it at ~7% and move the surplus to gels or solids, with plain water alongside. At high intensity, the maltodextrin + fructose duo (2:1) gets more carbs through at equal tolerance, because maltodextrin lowers the actual osmolality. Start under-dosed and build up session after session: the gut adapts.