Protein often receives most of the attention in performance nutrition conversations. Athletes debate whey versus casein, meal timing, amino acid profiles, and total daily intake in an effort to maximize muscle growth and recovery. Carbohydrates, meanwhile, frequently get reduced to oversimplified discussions around whether they are “fast” or “slow,” or whether athletes should eat more or less of them.
But for serious athletes, carbohydrate strategy becomes far more complex than total grams consumed.
Carbohydrates affect training output, glycogen restoration, hydration status, nervous system function, recovery speed, and even how comfortable an athlete feels while training. The exact same amount of carbohydrates can produce completely different outcomes depending on the source, the digestion rate, and when they are consumed.
For a strength athlete performing repeated heavy sets of squats, a hybrid athlete moving from deadlifts into conditioning work, or an endurance athlete preparing for a two-hour run, the energetic demands are very different. Understanding how carbohydrates behave in the body allows athletes to move beyond generic nutrition advice and build a system that actually supports how they train.
Why Digestion Rate Matters
Digestion rate refers to how quickly carbohydrates move through the digestive system, enter circulation, and become available for use as energy.
On the surface, it may seem that faster digestion would always be superior. More rapidly available energy should theoretically equal better performance. In practice, physiology is more nuanced.
During intense exercise, blood flow shifts dramatically throughout the body. Working muscles receive increased blood supply while digestion becomes a lower priority. The body essentially reallocates resources toward movement and away from processing food.
This creates an important challenge.
Athletes need fuel to become available quickly enough to support training demands, but they also need carbohydrates that can do so without creating excessive digestive stress.
Anyone who has consumed a thick sports drink before a hard training session and felt bloated, heavy, or nauseous has experienced this issue firsthand. The problem often is not the amount of carbohydrates consumed. The issue frequently comes down to the characteristics of the carbohydrate source itself.
How rapidly nutrients leave the stomach and enter circulation can influence how stable energy feels throughout training.
If fuel becomes available too slowly, athletes may notice decreasing performance as sessions progress. If digestion creates excessive gastrointestinal burden, energy may feel inconsistent and discomfort can become a limiting factor.
The goal is not simply consuming carbohydrates. The goal is delivering usable fuel efficiently.
Glycogen: The Fuel Tank Athletes Constantly Draw From
Carbohydrates support performance largely because they replenish glycogen.
Glycogen represents stored carbohydrates found primarily in skeletal muscle and the liver. Muscle glycogen acts as local fuel during muscular contractions, while liver glycogen helps maintain blood glucose availability for the entire body.
During high-intensity exercise, glycogen use increases significantly.
Heavy resistance training, sprint work, interval training, and repeated explosive movements rely heavily on glycolytic metabolism, meaning they depend substantially on stored carbohydrate availability.
As glycogen availability declines, several things begin occurring simultaneously.
Force production starts decreasing.
Bar speed slows.
Explosiveness declines.
Perceived exertion rises.
Mental focus deteriorates.
Reaction time becomes slower.
Many athletes interpret this as poor motivation or insufficient caffeine intake when, in reality, fuel availability may simply be declining.
Endurance athletes experience similar effects. As glycogen stores become progressively depleted during prolonged exercise, maintaining pace becomes increasingly difficult. This phenomenon is often described as “hitting the wall.”
Maintaining carbohydrate availability throughout training can help preserve performance and delay fatigue.
Understanding Osmolality
Ever wonder why some drinks feel light, and others feel like concrete? One concept that rarely gets discussed in sports nutrition but has major implications for athletes is osmolality.
Osmolality describes the concentration of dissolved particles within a solution.
In practical terms, it reflects how concentrated a beverage becomes after carbohydrates, electrolytes, and other ingredients are added.
A drink with higher osmolality contains more dissolved particles and may pull additional water into the digestive tract before absorption occurs.
This matters because gastric emptying speed can influence how quickly nutrients and fluids become available.
Highly concentrated solutions may slow stomach emptying and increase the likelihood of symptoms such as:
- bloating
- cramping
- stomach heaviness
- gastrointestinal discomfort
- nausea during exercise
For athletes training at high intensity, this becomes problematic because the stomach essentially becomes a bottleneck.
Instead of efficiently delivering fuel and fluids to working muscles, digestion slows and comfort decreases.
Lower-osmolality solutions generally empty from the stomach more rapidly, potentially improving tolerance and allowing athletes to consume meaningful amounts of carbohydrates without feeling weighed down.
This characteristic is one reason certain performance carbohydrates have become increasingly popular.
Understanding Different Carbohydrate Sources
Highly Branched Cyclic Dextrin (HBCD)
Highly Branched Cyclic Dextrin has become increasingly common in performance nutrition because it combines several characteristics athletes value simultaneously.
Its molecular structure forms large cyclic clusters that maintain relatively low osmolality despite providing substantial carbohydrate delivery.
Practically, this means athletes may be able to consume larger carbohydrate amounts while maintaining digestive comfort.
During long hypertrophy sessions, hybrid training, or endurance work, maintaining energy availability becomes increasingly important. HBCD may help support this by rapidly leaving the stomach while delivering usable carbohydrates throughout exercise.
Benefits and applications:
- Lower osmolality
- Rapid gastric emptying
- Reduced stomach heaviness
- Stable energy availability
- Supports glycogen maintenance during training
Best uses:
- Intra-workout nutrition
- Long lifting sessions
- Hybrid training
- Endurance work
- Post-workout recovery
Waxy Maize Starch
Waxy maize starch consists primarily of amylopectin, a highly branched carbohydrate structure.
Like HBCD, waxy maize gained popularity because of its potential to support carbohydrate delivery while maintaining relatively favorable digestion characteristics.
For athletes training multiple times per day or accumulating high weekly training volume, glycogen restoration becomes increasingly important.
Recovery is not simply about feeling less sore. Recovery determines how prepared the body is for the next training stimulus.
Benefits and applications:
- Supports glycogen replenishment
- Lower digestive burden for many athletes
- May support recovery between repeated sessions
Best uses:
- Post-workout recovery
- Endurance training
- Higher volume programs
Dextrose
Dextrose is pure glucose and represents one of the most rapidly available carbohydrate sources in sports nutrition.
Because it enters circulation quickly, dextrose can provide an immediate substrate for working muscles and rapidly support glycogen restoration.
However, rapid absorption does not necessarily mean better in every context.
Larger amounts of rapidly absorbed simple carbohydrates alone may create more dramatic fluctuations in energy and digestive comfort for some individuals.
Benefits and applications:
- Immediate energy availability
- Rapid glycogen replenishment
- Useful during intense glycolytic activity
Best uses:
- Post-workout
- High-intensity training
- Short-duration performance work
Maltodextrin
Maltodextrin functions somewhat differently than many athletes expect.
Although technically considered a complex carbohydrate, digestion occurs relatively rapidly.
Its neutral taste profile and ease of mixing make it common within sports formulas.
Benefits and applications:
- Rapid digestion
- Easy formula integration
- Effective carbohydrate delivery
Best uses:
- Intra-workout formulas
- Recovery nutrition
Dietary Carbohydrate Sources
Sports supplements can provide advantages around training windows, but foundational nutrition remains critical.
Examples include:
- White rice
- Potatoes
- Fruit
- Orange juice
- Honey
- Sourdough bread
- Homemade fruit smoothies
Whole foods provide more than carbohydrates alone. Potassium, vitamins, minerals, fluid, and additional nutrients all contribute to performance and recovery.
Fruit deserves particular attention because it often provides glucose and fructose together. Since these carbohydrates utilize different transport systems in the intestine, combining them may improve total carbohydrate delivery and oxidation compared to relying on a single source.
This concept has become increasingly important in endurance nutrition, where maximizing carbohydrate utilization during prolonged events can significantly influence performance.
Quick Guide to Building Your Own Custom Carbs
One of the advantages of True Nutrition’s customization system is that athletes can build formulas around training demands rather than relying on a generic one-size-fits-all product.
Strength and hypertrophy focus
- HBCD: 70%
- Dextrose: 30%
This combination provides stable energy support during training while supplying rapidly available glucose for repeated muscular contractions.
→ Shop this Blend
Hybrid athlete and endurance focus
- HBCD: 50%
- Waxy Maize: 50%
This approach prioritizes sustained fuel delivery with reduced digestive burden during longer sessions.
Recovery emphasis
- Waxy Maize: 50%
- Dextrose: 50%
This combination focuses on rapidly replenishing depleted glycogen stores following demanding training.
→ Shop this Blend
Practical Application
- Match carbohydrate type to the energetic demands of training rather than assuming all carbohydrate sources perform similarly.
- Consider lower-osmolality carbohydrate sources if traditional sports drinks create digestive discomfort.
- Use intra-workout carbohydrates during sessions lasting approximately 60-90 minutes or longer.
- Pair post-workout carbohydrate intake with protein to support glycogen restoration and recovery.
- Track energy levels, training quality, recovery, and digestive comfort to determine which strategies work best for your body.
Carbohydrates are often viewed simply as fuel, but for athletes, they function more like a performance system. They influence hydration, energy delivery, muscular output, nervous system performance, and recovery capacity. Understanding digestion rate, carbohydrate structure, and timing allows athletes to move beyond guessing and begin building a nutritional strategy that matches the demands of real training.
References
Burke LM, Hawley JA, Wong SH, Jeukendrup AE. Carbohydrates for training and competition. Journal of Sports Sciences. 2011.
Jeukendrup AE. Carbohydrate intake during exercise and performance. Nutrition. 2004.
Cermak NM, van Loon LJ. The use of carbohydrates during exercise as an ergogenic aid. Sports Medicine. 2013.
Kerksick CM et al. International Society of Sports Nutrition Position Stand: Nutrient Timing. Journal of the International Society of Sports Nutrition. 2017.
Takii H et al. Highly Branched Cyclic Dextrin improves gastric emptying and exercise performance. Journal of Nutritional Science and Vitaminology. 2005.
Jentjens RL, Jeukendrup AE. Determinants of post-exercise glycogen synthesis during short-term recovery. Sports Medicine. 2003.
Thomas DT, Erdman KA, Burke LM. Nutrition and Athletic Performance. Journal of the Academy of Nutrition and Dietetics. 2016.
Ivy JL. Regulation of muscle glycogen repletion, muscle protein synthesis, and repair following exercise. Journal of Sports Science and Medicine. 2004.