Carbohydrates and Power Retention During Long Rides
Discover how mid-ride carbohydrate consumption influences late-session power outputs and next-day athletic performance based on laboratory trials.
Fueling during a long ride is a performance decision as well as a packing decision. Two laboratory studies examined carbohydrate intake during demanding cycling, measuring different outcomes: power after a long effort and performance the following day nih.gov nih.gov. Their results are useful, but neither gives a guarantee for every recreational ride.
Power after two hours of cycling
In a 2019 study with 16 participants, researchers used a three-minute all-out cycling test to estimate end-test power and work performed above that power nih.gov. Participants completed the test fresh and after different durations of heavy-intensity cycling nih.gov.
After two hours with a placebo drink, end-test power was 9% below the fresh condition nih.gov. Consuming 60 grams of carbohydrate per hour attenuated the reduction in end-test power, but did not preserve work above end-test power nih.gov. The latter measure had already declined after 80 minutes with placebo nih.gov.
End-test power was an estimate derived from a specific test, not a speed someone can sustain indefinitely without fatigue nih.gov. The result suggests carbohydrate availability influenced one aspect of late-session performance nih.gov. It does not show that fueling prevents every form of fatigue or restores a fresh sprint nih.gov.
What happened the next day?
A 2023 study of seven trained male cyclists compared matched workloads under placebo and carbohydrate conditions nih.gov. Participants completed prolonged cycling at a power corresponding to 68% of maximal oxygen uptake, followed by hard intervals nih.gov. Carbohydrate was supplied at one gram per kilogram of body weight per hour during the prolonged segment nih.gov.
The placebo condition always came first and the carbohydrate condition second, at least a week apart nih.gov. The diet was standardized so the conditions provided equal total energy nih.gov. That small sample and fixed order limit confidence in applying the result broadly nih.gov.
The next-day time trial showed differences after carbohydrate versus placebo, along with altered blood amino acid concentrations nih.gov. However, urinary markers of protein degradation did not differ nih.gov. The findings do not establish that the placebo condition caused measurable muscle loss or that protein preservation explains the performance difference nih.gov.
Put fueling targets in context
When reviewing a long-ride plan, note its duration and demands alongside the carbohydrate amount you intend to carry nih.gov nih.gov. Check the carbohydrate content of the actual food or product: an assumed number of gels is not a reliable dose nih.gov nih.gov. The studies support planning fuel for demanding prolonged exercise, with realistic expectations about what that fuel can and cannot change nih.gov nih.gov.