Why is it not worth refreshing solely with caffeine gel?

Caffeine is one of the most studied and effective performance-enhancing agents. When consumed at the right time and in appropriate amounts, it can improve alertness, reduce the subjective perception of effort, and provide a measurable performance advantage in endurance sports.

Therefore, it's worth managing its intake consciously.

If an athlete covers all their energy needs with caffeinated gels or other caffeinated sports nutrition products, they can easily lose control over their total caffeine intake. The body continuously needs energy, but caffeine demand does not follow the same rhythm. A caffeinated gel consumed every 30-45 minutes could therefore lead to a stimulant load that is not actually necessary to maintain performance.

Caffeine can be a useful tool in a hydration and nutrition plan. Instead of automatically consuming it with every energy dose, it should be used with a specific purpose and in pre-calculated amounts.

Energy and Caffeine Serve Two Different Needs

Athletes consume gels, sports drinks, or other energy sources to provide carbohydrates and usable energy to working muscles. During longer efforts, this needs to be replenished regularly, as the body's carbohydrate stores are finite.

Caffeine plays a different role. It primarily acts on the central nervous system: it blocks adenosine receptors, can reduce feelings of fatigue, increase alertness, and in certain situations, help maintain concentration or higher performance.

It follows that the rhythm of carbohydrate intake and caffeine dosing do not necessarily coincide. An athlete may need energy every half hour, but does not need caffeine intake with the same frequency.

Research suggests that the most consistently studied performance-enhancing range for caffeine is approximately 3-6 mg per kilogram of body weight, although smaller amounts can be effective for some athletes. Very high doses generally do not provide additional performance benefits, but the likelihood of unpleasant side effects increases. Individual reactions are influenced by genetic predispositions, regular caffeine consumption, fitness level, time of day, and caffeine sensitivity. ISSN position statement on caffeine and sports performance

How Does 50 mg of Caffeine Add Up?

One serving of caffeinated Hammer Gel contains 50 mg of caffeine. This is a moderate amount in itself. The question becomes important when an athlete consumes a caffeinated version every time.

If they eat one serving every 30 minutes, they ingest 100 mg of caffeine per hour. Consuming it every 45 minutes means an intake of approximately 67 mg per hour.

To this can be added pre-race coffee, a caffeinated sports drink, cola, capsules, chewing gum, or other energy-boosting products. A morning coffee and four caffeinated gels combined can easily reach a total of 250-350 mg.

According to the European Food Safety Authority, for healthy adults, a single intake of up to 200 mg and a total daily intake of up to 400 mg of caffeine generally do not raise safety concerns. This is a general safety assessment, not a dosing target for sports performance, and does not override individual sensitivity. EFSA information on caffeine safety

Caffeine Does Not Clear Between Two Energy Doses

Caffeine is absorbed relatively quickly, but its breakdown takes several hours. Its average half-life is often around four to six hours, with significant individual variations. This means that when an athlete takes the next 50 mg dose, a significant portion of the previous dose's caffeine content is still in their body.

During a long race, therefore, we are not talking about isolated, short-acting doses. Caffeine gradually accumulates, and the amount in the blood can be much higher in the second half of the race than what the 50 mg label value of the last gel alone would suggest.

Meanwhile, the effect of caffeine can last longer than the momentary boost an athlete perceives. It may happen that someone tries to counteract decreasing energy levels with another dose of caffeine, when in reality they would need more carbohydrates, fluids, electrolytes, or a more appropriate pace choice.

Does Caffeine Really Increase Heart Rate?

The effect on heart rate is more complex than simply causing a higher value for everyone. Caffeine can increase sympathetic nervous system activity, elevate catecholamine levels, and temporarily raise blood pressure. Some athletes may experience a rapid heartbeat, stronger palpitations, or a higher heart rate during exertion. For others, the change in heart rate is barely measurable, especially with regular caffeine consumption.

In endurance performance, it is generally advantageous if an athlete can maintain a given pace or performance with less physiological stress. Continuous caffeine intake can make it difficult to interpret heart rate data. A higher value can be due to intensity, heat, dehydration, fatigue, race anxiety, or the effect of caffeine.

Furthermore, caffeine can reduce the perception of effort. This can make an athlete feel the same pace is easier and unconsciously speed up. In such cases, a higher heart rate may partly be a consequence of increased performance. Caffeine can thus raise measured heart rate by causing only a small direct change in heart rate, but it enables or encourages more intense work.

With a properly tested caffeine strategy, this can become a performance advantage. With uncontrolled dosing, it's easier to start faster than planned, deplete reserves too early, and then experience a significant drop in performance at the end of the race.

Blunting the Sensation of Fatigue is Both an Advantage and a Risk

One of caffeine's valuable properties is its ability to mitigate the subjective feeling of effort. Athletes can feel fresher, more focused, and maintain race pace more easily.

However, fatigue is also important feedback. It signals the sustainability of pace, heat stress, energy supply status, neurological exhaustion, and muscle load. After multiple doses of caffeine, an athlete may be less accurate in perceiving how close they are to their limit.

This can be particularly crucial in long races, hot weather, or high-intensity efforts. Stimulated alertness does not replace available energy and does not automatically reduce the body's heat stress. An athlete may feel more alert even when the performance decline is actually due to dehydration, insufficient electrolyte intake, an overly fast starting pace, or depleted carbohydrate stores.

Restlessness, Tremors, and Less Accurate Decisions

In caffeine-sensitive athletes, even small amounts can cause internal restlessness, hand tremors, anxiety, excessive excitability, or palpitations. With higher total doses, these symptoms can appear even in those who regularly drink coffee.

Pre-race tension already activates the sympathetic nervous system. To this is added race intensity, heat, and gradually increasing caffeine levels. In this state, an athlete can more easily make hasty decisions: they might speed up more than planned, forget about fluid or electrolyte intake, or try to manage feelings of energy deficit with another caffeinated product.

In technical trail running, cycling, and long overnight races, alertness is beneficial. Excessive stimulation, however, can impair fine motor coordination and scatter attention. The optimal amount here is also individual, so it needs to be determined during training.

Gastrointestinal Problems May Also Arise

In some individuals, caffeine can increase bowel activity, causing an urgent need to defecate, nausea, heartburn, or reflux symptoms. During running, mechanical jarring, decreased blood flow to the digestive system, and higher intensity already increase the risk of gastrointestinal symptoms.

A single 50 mg dose of caffeine usually does not pose a significant burden. However, multiple caffeinated gels consumed consecutively can exacerbate symptoms in sensitive athletes, especially if they drink little water, consume too many calories, or use other caffeine sources.

In such cases, discomfort can be easily misinterpreted. The athlete might think they've run out of energy, take another gel, which further increases the amount of caffeine and digestibles.

Caffeine and Hydration

Caffeine is often referred to as a strong diuretic, leading many to believe that it automatically causes dehydration during exercise. Based on available research, moderate caffeine intake alone, especially during exercise and with adequate fluid intake, generally does not cause fluid loss to an extent that would significantly impair hydration.

The main problem with continuous caffeine consumption, therefore, is not simply its diuretic effect. More significant can be that stimulation alters the perception of effort, can promote higher intensity, and in sensitive athletes, can increase heat sensation or unpleasant cardiovascular symptoms.

Caution is especially important in warm environments. A 2024 study found that acute caffeine intake could improve cycling performance, while unfavorably affecting some indicators of thermoregulation. Other summaries found smaller, practically negligible temperature changes. Based on current evidence, caffeine is not automatically considered dangerous in heat, but individual tolerance and total dose must be taken seriously. Study on caffeine, performance, and thermoregulation

Afternoon Caffeine Can Impair Recovery

A long training session or race does not end at the finish line. A significant part of adaptation and progress occurs during recovery after exertion, of which sleep is one of the most important elements.

Due to caffeine's half-life, a significant portion of a dose consumed in the afternoon can still be present in the body in the evening. An athlete may still fall asleep, but the depth, continuity, and total duration of sleep can be impaired. In a controlled study, 400 mg of caffeine consumed even six hours before bedtime caused measurable sleep disturbance. The effects of caffeine timing on sleep

This is particularly important for afternoon marathons, long cycling events, ultra-races, and evening training sessions. The athlete may gain a temporary boost during the race, but then sleep worse on the very night when their body needs enhanced recovery.

The effect on sleep is highly dose-dependent. In a more recent study, a 100 mg dose caused much less sleep disturbance than a 400 mg single intake, again showing that the total amount is at least as important as the timing of the last caffeine intake. Dose, timing, and sleep - 2025 study

Regular Caffeine Consumption Modifies Response

Someone who consumes several coffees or energy drinks daily generally feels less of the same amount of caffeine. This does not necessarily mean that caffeine no longer affects them at all. Cardiovascular, nervous system, and sleep effects can still be present even if the dramatic alertness is missing.

High caffeine tolerance can encourage an athlete to use increasingly larger doses. In such cases, the performance benefit barely changes, while the likelihood of restlessness, stomach problems, headaches, palpitations, and sleep disturbances may increase.

The opposite situation is also common. Someone who consumes little caffeine in daily life may react strongly to even a single 50 mg gel. For them, a seemingly low dose based on the label may be sufficient, especially with race anxiety, high intensity, or hot weather.

When Can Caffeinated Gel Be Truly Useful?

Caffeinated gel provides the most value when its use has a clear purpose. This could be the final stage of a long race, maintaining alertness during an overnight ultra, the period before a decisive climb, or the point where concentration begins to decline due to fatigue.

For many athletes, it is more advisable to provide energy with caffeine-free Hammer Gel, HEED, or Perpetuem for longer efforts during the first part of the race. Caffeinated gel can be incorporated later, at a predetermined time. This ensures continuous energy supply while allowing control over the amount and timing of caffeine.

For a 70 kg athlete, the often-studied 3 mg/kg body weight caffeine means 210 mg. This is slightly more than four gels containing 50 mg of caffeine each. It does not follow that everyone needs such a large dose. Even 50-150 mg can be noticeable and performance-supporting, especially for a caffeine-sensitive athlete or in the late stages of a race.

When calculating the total daily amount, pre-race coffee and all other caffeine sources must also be considered.

Caffeine Needs to Be Trained Just Like Nutrition

Race day is not the appropriate time to try a new caffeine strategy. During training, it is worth observing how a given amount affects heart rate, perceived pace, stomach, concentration, and post-workout sleep.

During testing, it is useful to record the exact amount of caffeine consumed, the timing, other energy sources, temperature, and any symptoms the athlete experienced. After a few training sessions, it may become clear whether caffeine is needed, at which stage it provides the greatest benefit, and where unpleasant side effects begin.

In cases of arrhythmia, untreated high blood pressure, severe anxiety, reflux, pregnancy, caffeine sensitivity, or regularly occurring palpitations, the use of caffeine should be discussed with a doctor.

Targeted Caffeine Use Is More Valuable Than Continuous Dosing

Caffeinated Hammer Gel can be a useful, precisely dosed tool. Its 50 mg caffeine content allows the athlete to build up intake in smaller steps, tailored to their own tolerance.

The problem begins when every planned energy dose automatically contains caffeine. Over four to six hours, the amount of caffeine can gradually accumulate, while heart rate and perception of effort can change, digestive or nervous system issues may appear, and late doses can impair sleep.

Energy supply should be built on caffeine-free foundations. This way, the caffeinated product is reserved for the phase where it can truly contribute to performance. The relevant question, therefore, is not merely how much caffeine one can "fit in." It helps much more to consider when it is truly needed and what we want to achieve with it.