Nutrition, recovery, and adequate hydration are equally important to building proper endurance for long distance runners, which goes beyond daily workouts on the road and track.

I’ll briefly focus on Nutrition but try to leave no stone unturned regarding this critical topic and component of endurance training.

A balanced diet for endurance

Remember that flexibility and experimentation still have their place in nutritional planning and that there is no one-size-fits-all approach to nutrition for elite runners. To remain nutritionally flexible, athletes should increase the diversity and range of foods and experiment with different food types on their training runs to find the best.

Carbohydrates

Carbohydrates are the primary fuel source for endurance athletes and the most variable in terms of daily requirements based on duration and intensity of training.

According to the Academy of Nutrition and Dietetics (AND) and the American College of Sports Medicine (ACSM), moderate exercise (1 hour per day (h/day)) requires 5–7 g per kilogram of body weight per day (g/kg/day) of carbohydrate (CHO). Most collegiate and elite runners will be in moderate to high-intensity exercise (1–3 h/day), requiring 6–10 g/kg/day. Ultra-endurance athletes with extreme levels of commitment to daily activity (4–5 h of moderate to high-intensity exercise daily) may need up to 8–12 g/kg/day.​

There are three primary sources of carbohydrates.

Sugar is the simplest form of carbohydrate and occurs naturally in some foods, including fruits, vegetables, milk and milk products. Types of sugar include fruit sugar (fructose), table sugar (sucrose) and milk sugar (lactose)

Starch is a complex carbohydrate, meaning it is bonded with many sugar units. Starch occurs naturally in vegetables, grains, and cooked dry beans and peas.

Fibre is also a complex carbohydrate. It occurs naturally in fruits, vegetables, whole grains, and cooked dry beans and peas.

For endurance athletes, prioritizing complex carbohydrates like whole grains (oats, quinoa, brown rice), starchy vegetables (potatoes, sweet potatoes), fibre-rich fruits and vegetables, and legumes and beans is crucial for sustained energy and recovery. 

Protein

Protein is required for the structure, function, and regulation of the body’s tissues and organs. Adequate protein intake, as well as the timing of intake, is critical to the health and success of endurance athletes.

The Academy of Nutrition and Dietetics (AND) and the American College of Sports Medicine (ACSM) recommend protein intake for athletes in the 1.2–2.0 g/kg/day range.​​ The International Society of Sport Nutrition recommends athletes consume 1.4–2.0 g/kg/day.

Endurance athletes should get enough protein at breakfast and replenish it in a sufficient and timely manner during the day.

The ideal time to optimize protein intake is 30 minutes after workouts.

Fats

Fats are fundamental components of cell membranes, playing roles in signalling and transport, nerve function, providing insulation and vital organ protection, and are the source of essential dietary fatty acids.

 Athletes who chronically restrict fat to <20% of their total energy are at risk of low intake of fat-soluble vitamins, carotenoids, and essential fatty acids. This is especially important for endurance athletes who are susceptible to declines in testosterone, as encountered with overtraining.

Periodized Nutrition for Training:

Pre-competition:

Carbohydrates

For endurance events less than 90 minutes, replenishing muscle and liver glycogen lost during the day has been recommended with a CHO-rich diet of at least 6 g/kg​ and up to 7–12 g/kg​​ in the 24 hours before the event.

For events lasting more than 90 minutes, glycogen supercompensation, or “carbo-loading,” in the preceding 36–48 hours may help improve performance by 2–3%. 1–4 g/kg CHO is recommended for a final top-off of glycogen stores in the final 1–4 h before the event.

Protein

A 0.3 g/kg protein pre-exercise dose is recommended for athletes to help prevent muscle breakdown in more extended endurance events.

During competition:

Carbohydrates

Active fueling strategies are recommended to maintain CHO levels for activities lasting more than 60 minutes. For efforts between 1 and 2.5 h, a 6–8% CHO solution totalling 30–60 g/h is commonly recommended. These are the common concentrations found in today’s sports drinks. 

8-10% CHO blend of glucose and fructose results in higher ingestion rates, and these combinations also improve GI tolerance. As we stated earlier, to control GI discomfort, it’s important to practice fueling strategies during training. The closer the practice is to race day, the better the picture athletes will have of their response to a nutrition strategy.

Protein

During endurance events, the ISSN recommends approximately 0.25 g/kg protein per hour when taken with carbohydrates to minimize potential muscle damage. This can improve subjective feelings of muscle soreness and may increase muscle protein synthesis and net protein balance.

Recovery:

Carbohydrates

Studies have shown that daily high-carbohydrate fueling (8–10 g/kg/day) can restore pre-exercise glycogen values within 24 hours.

If glycogen repletion is needed quickly for an event with less than 4 hours of recovery time, refuelling at 1.2g/kg/h for the first few hours can help. These studies also suggest eating high-glycemic-index foods during this quick refuelling strategy.

Foods with a high glycemic index (GI) cause a rapid rise in blood sugar levels. These include refined grains like white bread and rice, desserts, candies, and highly processed foods, and they should be consumed in moderation, especially if managing blood sugar levels. 

Protein

Protein doses of 0.3g/kg (about 15-30g) are suggested immediately or within 2 hours after exercise. Using ratios helps simplify reloading strategies after workouts.

While a speed-power athlete might need a 1:1 ratio of CHO to Protein during a technical session (e.g., 20g CHO & 20g Protein), this ratio will change for endurance athletes depending on the duration of the activity.

For sessions lasting 60 minutes or more, 3:1 (e.g., 75g CHO & 25g Protein) is recommended, and for longer 2+ hour efforts, aim for 4:1 (e.g., 100g CHO & 25g Protein).

Whole foods are the best choice for achieving these numbers, and runners should not rely solely on sports supplements or powders.

Hydration:

For every kilogram of body weight lost during exercise, we can estimate one litre of fluid lost. The recovery hydration recommendations are 1.5 X BW loss over 4 hours of drinking. This means replacing every kilogram of body weight lost during a session with 1.5 litres of fluid over the next four hours. The extra 0.5 litres are added to cover the fluid lost through urine and continued sweating during that four-hour rehydration period.

During an endurance event, adequate hydration levels allow the body to sweat more as a cooling mechanism to dissipate heat. 

By following instinctive thirst and monitoring parameters such as body weight, urine colour, race pace, body temperature, and environmental temperature with each workout, athletes can better dial in their individual hydration needs.​

Body Weight:

This is a key performance indicator for elite distance runners.  Having a very high power-to-weight ratio happens to elite athletes with very low body fat levels during their peak season. 

However, from an athlete’s general health perspective, it is not sustainable to be at peak body composition year-round, so these qualities should be strategically periodized.

Research suggests body composition ranges for elite female middle-distance runners to be at ~8% to 12% body fat and for elite males, ~4% to 6% in peak competition season.

Here is how Kenyan runners deal with Ideal running Weight and how to deal with it in training

Iron:

Iron levels are an important factor in athletes’ health and performance, but low iron status is common among endurance athletes, particularly females. This can occur due to factors from both exercise and nonexercise origins (diet and heavy menstrual bleeding). Routine screening of iron status, generally every six months of training, will help athletes stay ahead of any potential issues.

Including iron-rich foods in the diet (e.g., red meats, nuts, seeds, fortified cereals, leafy green vegetables, legumes, etc.) and using strategies to enhance bioavailability (mixing plant iron sources with Vitamin C or animal iron sources) can help athletes maintain adequate iron levels.​13​

 When dietary interventions aren’t enough, or the athlete is unresponsive, seeking medical advice on additional supplementation strategies is essential.