Fuelling for Endurance: A Complete Guide to Sports Nutrition and Supplements

For endurance athletes, nutrition is more than just fuelling up for the next meal—it's the backbone of sustainable performance and recovery. Whether you’re preparing for a marathon, triathlon, or a long cycling race, what you eat before, during, and after training or competition has a direct impact on your ability to perform at your peak and recover effectively.
Endurance sports demand prolonged exertion, making energy availability crucial to maintaining performance over hours of activity. Glycogen (stored carbohydrates) is the body’s primary fuel source, and inadequate nutrition can lead to early fatigue, poor performance, or even injury​.

When it comes to endurance training and competitions, understanding the types of sports nutrition available is essential for optimal performance. Each type of sports drink or product serves a specific purpose, helping athletes maintain energy levels, hydration, and recovery. Below is a breakdown of the main categories of sports nutrition products.

Sports drinks are designed to provide hydration, electrolytes, and in some cases, energy in the form of carbohydrates. There are three main types of sports drinks, classified based on their osmolality (the concentration of solutes such as sugars and salts in relation to blood).

• Isotonic Drinks: These drinks have a similar concentration to blood, making them effective for balancing hydration and energy delivery during exercise. They typically contain 6-8% carbohydrates and are ideal for short-duration, high-intensity workouts. However, due to their relatively high sugar content, they may cause gastrointestinal issues if consumed in large amounts or in hot conditions​.
• Hypotonic Drinks: With a lower concentration of carbohydrates and electrolytes than blood, hypotonic drinks are absorbed quickly, making them the best choice for rapid rehydration. These are useful during longer training sessions or events in hot weather, where hydration is more important than energy delivery​.
• Hypertonic Drinks: These drinks have a higher concentration of carbohydrates than blood and are primarily used for post-exercise recovery to replenish glycogen stores. Due to their high solute concentration, they can draw water into the gut, which may exacerbate dehydration during exercise​.

Energy drinks usually contain carbohydrates and stimulants such as caffeine or taurine. Their primary purpose is to boost both energy levels and mental alertness during prolonged efforts. While these drinks can help delay fatigue, it’s important to be cautious, as they may lead to dehydration due to their diuretic effects.

These products are designed to deliver quick-absorbing carbohydrates during exercise. Typically, they provide 20−30 grams of carbohydrates per serving. Many products combine different types of sugars, such as glucose and fructose, to enhance absorption rates and improve energy supply. Some also contain electrolytes to support hydration during endurance activities​.

Electrolyte drinks are designed specifically to replenish key minerals like sodium, potassium, magnesium, and calcium lost through sweat. Unlike sports drinks, these products are typically low in carbohydrates or sugar-free, focusing on fluid replacement. Sodium content is critical, usually around 300−600 mg per liter, as it helps maintain fluid balance in the body. Other minerals, while important for general health, do not directly aid in real-time hydration and should be replenished through the base diet​.

For endurance athletes, protein supplementation is crucial for muscle repair and recovery. After long or intense training sessions, protein helps rebuild muscle tissue and prevents muscle breakdown. Common types of protein supplements include:

• Whey Protein: Fast-digesting, ideal for post-workout recovery.
• Casein Protein: Slow-digesting, supporting muscle repair over extended periods.

Protein supplements can be consumed after workouts or as part of daily nutrition to meet protein requirements.

For endurance athletes, targeted supplementation can enhance performance when combined with a solid nutrition strategy. Below is a breakdown of key supplements that improve athletic output, focusing on their effects, mechanisms of action, and usage in sports.

Caffeine is one of the most widely used and researched supplements. It acts as a stimulant by blocking adenosine receptors in the brain, reducing the perception of effort, and enhancing alertness and focus. Studies show that caffeine can improve endurance, allowing athletes to maintain high intensity for longer. The ideal dosage is typically 3–6 mg per kg of body weight, consumed 60 minutes before exercise​.
However, over time, the body develops tolerance to caffeine, reducing its effectiveness. Regular caffeine use may require higher doses to achieve the same performance-enhancing effects, but this increases the risk of side effects such as anxiety or gastrointestinal discomfort.

Creatine is well-known for improving performance in high-intensity, short-duration sports, but it also shows benefits for endurance athletes in specific scenarios. Creatine works by replenishing phosphocreatine stores in muscles, which helps regenerate ATP, the body’s energy currency, during brief, explosive efforts​. For endurance athletes, creatine can enhance performance during short, high-intensity bursts, such as sprints or climbing efforts during a race.
A standard loading phase of 20 grams per day for 5−7 days is recommended to maximize creatine stores, followed by a maintenance dose of 3−5 grams per day. However, creatine may cause weight gain due to water retention, which could negatively impact performance in sports where body weight is a concern​.

Nitric oxide (NO) is a molecule that promotes vasodilation, increasing blood flow and oxygen delivery to working muscles. Supplementation with nitrates, such as beetroot juice, has been shown to enhance endurance performance by improving oxygen efficiency, especially in sports that require sustained aerobic effort, like cycling or long-distance running.
Studies suggest that nitrate supplementation may be most effective for endurance sports lasting 4-30 minutes, though its benefits diminish at higher intensities​.

Beta-alanine increases carnosine levels in muscles, which buffers acid buildup (hydrogen ions) during high-intensity exercise. This delay in muscle acidosis reduces fatigue, allowing athletes to sustain high-intensity efforts for longer durations​.
Beta-alanine is particularly effective for endurance athletes engaging in repeated high-intensity efforts, such as interval training or sports like swimming and cycling. Regular supplementation of 4–6 grams per day over several weeks is recommended to elevate muscle carnosine levels​.

Sodium bicarbonate acts as a buffer, neutralizing the acid produced in muscles during intense exercise. This allows athletes to sustain higher intensities for longer by delaying the onset of muscle fatigue. Sodium bicarbonate is particularly beneficial in sports involving intermittent high-intensity efforts, such as rowing, track cycling, or sprint swimming​.
The typical dose is 300 mg per kg of body weight, taken 60–90 minutes before exercise. However, some athletes may experience gastrointestinal discomfort, so it’s important to test this supplement in training before using it in competition​.

A balanced, nutrient-dense diet is essential for athletes to maintain energy levels. The base diet, comprising everyday meals, forms the bedrock of an endurance athlete’s nutrition strategy. This diet should consist of whole grains, lean proteins, healthy fats, and plenty of fruits and vegetables to provide the carbohydrates, protein, and micronutrients necessary to fuel workouts and support recovery.
Importantly, sports nutrition products (like energy gels, recovery shakes, and supplements) cannot correct poor meal choices or insufficient nutrition in the base diet. Without a proper foundation, even the best supplements will have limited effectiveness​.

One of the most common mistakes endurance athletes make is increasing their training volume without adequately increasing their calorie intake. As training demands rise, athletes need more energy, which must be met through proper adjustments in nutrition.
Failure to adjust the diet accordingly can lead to several negative consequences:

1. Micronutrient deficiencies: Without enough vitamins and minerals, key bodily functions like oxygen transport, bone health, and energy production suffer.
2. Muscle loss: Inadequate carbohydrate intake forces the body to break down muscle protein for energy, leading to muscle loss and impaired recovery.
3. Weakened immune system: Insufficient nutrition can compromise immune function, making athletes more prone to illness.
4. Inability to sustain training intensity: Without sufficient calories and nutrients, athletes will struggle to meet the demands of high-volume training, leading to fatigue and diminished performance​.
5. Increased risk of injury: Inadequate nutrition affects bone density and muscle strength, making athletes more susceptible to overuse injuries and stress fractures.

This imbalance between energy intake and output can lead to a condition known as Relative Energy Deficiency in Sport (RED-S). RED-S affects not only performance but also hormone balance, bone health, and immune function​

For endurance athletes, performance and recovery are deeply connected to nutrition. A well-structured, nutrient-dense base diet is essential for providing the energy and nutrients required for prolonged physical activity. No sports nutrition supplement can replace poor food choices, making a balanced daily diet the cornerstone of sustained energy, muscle maintenance, and recovery.
Failing to align nutrition with training demands can result in negative outcomes like micronutrient deficiencies, muscle loss, and weakened immunity. Adjusting caloric and nutrient intake is crucial to avoiding a drop in performance and sustaining long-term gains.
Sports nutrition products—such as isotonic drinks, energy gels, and protein supplements—play a supportive role during intense training or competition, helping athletes maintain energy and hydration. Supplements like caffeine, creatine, beta-alanine, and sodium bicarbonate can further enhance endurance, delay fatigue, and aid in recovery.
The right combination of nutrition and supplementation can push athletes to new performance levels, optimize recovery, and help them thrive under increased training loads.

Ready to take your endurance training to the next level? With NeverLow, you can get personalized nutrition plans and recommendations tailored to your specific needs. From fuelling strategies to post-workout recovery, NeverLow helps you optimize your performance. Start fuellilng smarter and achieve your goals today!