Why might a nutrition strategy relying solely on gels or isotonic drinks be insufficient in the long run?

Gels and sports drinks provide a fast, easily dosable source of carbohydrates. For shorter workouts and races, this can exactly meet the body's needs. However, as the effort extends to three, four, six, or even ten hours, energy supply becomes more complex. Carbohydrates remain important, while the role of fats increases, and the utilization of amino acids may also intensify.

A refueling strategy consisting solely of gels or carbohydrate-rich sports drinks addresses only one part of this. The athlete continuously receives carbohydrates but no external protein, and the consumed food contains little to no fat. For a few hours, this might work well. However, during longer periods of exertion, an increasing discrepancy can develop between the composition of the products and the changing needs of the body.

Gel is a quick energy source, but not a multi-hour liquid meal

The primary function of a gel is to provide easily transportable and quickly consumable carbohydrates. Hammer Gel is based on maltodextrin, thus fitting well into Hammer Nutrition's simple-sugar-avoiding fueling system. For shorter efforts, it can be used as a standalone energy source, and for longer races, as a supplement to Perpetuem.

However, gel is almost exclusively a carbohydrate source. It does not contain sufficient protein and fat to provide the more complete energy profile designed for multi-hour exertion. If someone consumes only gel for eight or ten hours, their body continuously receives the same single type of nutrient, while their metabolic situation constantly changes.

The longer the exertion, the more noticeable the difference can become between rapid carbohydrate replenishment and sports nutrition designed for the long term.

Isotonic drink combines energy with fluid

Isotonic drinks generally try to provide carbohydrates, fluids, and electrolytes simultaneously. This seems like a practical solution, but the three needs do not always change in the same proportion.

In cool weather, an athlete may still need energy while sweating less and desiring less fluid. In hot weather, fluid and electrolyte needs can significantly increase, while the digestive system's capacity to absorb energy may decrease. If everything comes from a single drink, the athlete can only drink more by also consuming more carbohydrates and electrolytes.

This can easily lead to excessive energy intake during a long race. If the athlete drinks less of the energy drink due to stomach problems, their fluid intake also decreases. Dehydration can further slow gastric emptying, making the problem a self-reinforcing process.

A system that can be managed separately provides greater freedom. Energy can be supplied by Perpetuem or other Hammer energy sources, fluid can come from plain water, and electrolyte intake can be adjusted to the extent of sweating with an Endurolytes product.

More carbohydrates do not replace missing protein

Increasing the dosage of gels and sports drinks leads to more carbohydrates entering the body. This does not change the protein supply. However, carbohydrates themselves can help preserve the body's own proteins, as with available energy, the use of amino acids for energy production may be less.

During several hours of endurance exertion, however, protein turnover and amino acid oxidation increase. According to a systematic review published in 2025, protein contributed an average of approximately 3.3 percent to the total energy expenditure of endurance exercise, while protein oxidation more than doubled compared to rest. Other estimates suggest a higher proportion for long, intense, or low-glycogen exertions. The scientific background of the question is discussed in detail in a recent protein metabolism review.

The amount of carbohydrates consumed, the state of glycogen stores, intensity, and overall energy deficit all influence the extent to which amino acid utilization increases. Therefore, it is not possible to uniformly state for all athletes exactly how much protein they need at a specific time.

Hammer Nutrition's approach accounts for small amounts of protein during long efforts. Perpetuem contains carbohydrates and soy protein in approximately an 8:1 ratio. Carbohydrates remain the dominant external energy source, while plant-based protein provides amino acids to support increased protein turnover.

What does increased utilization of muscle proteins mean?

The body does not store a separate supply of amino acids for when it might need them during several hours of athletic exertion. Amino acids are found in working tissues, enzymes, and body proteins.

When carbohydrate stores decrease, energy expenditure is high, and the body finds it increasingly difficult to maintain energy balance, certain amino acids may become more involved in energy production and glucose synthesis. Hammer often describes this process as "cannibalization" of muscle tissue.

The term is illustrative, although from a physiological perspective, increased protein turnover, amino acid oxidation, and potential net protein loss are more precise descriptions. The small amount of soy protein in Perpetuem aims to provide an external amino acid source for this situation.

Protein consumed during exercise is not expected to completely eliminate muscle damage or significantly increase performance on its own. Adequate carbohydrate supply, well-chosen intensity, fitness level, and post-exertion recovery remain crucial. Protein is a supplementary element of long-term fueling.

What can happen if we consume only sweet products for hours?

One practical problem with fueling solely based on gels and sweet sports drinks is flavor fatigue. What is pleasant in the first hour may seem too sweet, too concentrated, or difficult to swallow after six to eight hours.

Flavor fatigue is not merely a matter of comfort. After a while, the athlete may reject the previously used product, consume less of it, or suddenly reach for completely different foods. The planned energy supply can easily fall apart then.

A very sweet taste can also increase nausea, especially in hot weather or during higher intensity. Perpetuem's more subdued flavor profile and small protein and fat content give a different sensation, which is why many athletes consume it more easily for several hours.

This is a matter of individual tolerance. Some tolerate gels well for a long time, while others develop a strong aversion to sweetness after just a few hours. The purpose of long training sessions before a race is to find out how an athlete's taste and digestion change over the hours.

What is missing from carbohydrate-only fueling?