Protein for Endurance Athletes: Needs & Timing

Endurance athletes need more protein than the general population, typically 1.2 to 2.0 g per kilogram of body weight each day, to repair muscle and adapt to training. Timing matters too: a dose of high-quality protein soon after a session, then regular serves every three to five hours, supports recovery better than one large protein meal at dinner. A whey protein like True Protein's WPI 90 is a simple way to hit that post-session target when food isn't practical.

Why do endurance athletes need protein if carbohydrate is their main fuel?

Carbohydrate powers long sessions, but protein is what repairs and rebuilds the body afterwards. Every run, ride or swim causes small amounts of muscle damage and breaks down proteins that then need replacing.

What does protein actually do for an endurance athlete?

Protein supplies amino acids (the building blocks your body uses to make and repair tissue). For endurance athletes, that work goes beyond muscle size:

• Muscle repair: fixing the micro-damage from repetitive loading, especially on long or hilly sessions.
• Mitochondrial growth: building more mitochondria, the parts of muscle cells that produce aerobic energy. This is a big part of how endurance fitness improves.
• Connective tissue and immune support: maintaining tendons, ligaments and immune cells under high training loads.

Does endurance training burn protein as fuel?

Yes, a small amount. During long sessions the body oxidises (burns for energy) some amino acids, particularly leucine. A review in Nutrition by McMaster University's Mark Tarnopolsky puts this at 1 to 6% of the total energy cost of endurance exercise, with low energy or carbohydrate intake pushing protein needs higher. A 2019 study in Medicine & Science in Sports & Exercise confirmed this: endurance-trained men who did interval training with low carbohydrate availability showed greater amino acid oxidation, and therefore higher protein needs, than when well fuelled. Fasted or low-carb sessions make protein after training even more important.

How much protein do endurance athletes need per day?

Most endurance athletes need 1.2 to 2.0 g of protein per kilogram of body weight per day. That is roughly 1.5 to 2.5 times the 0.8 g/kg recommended for the general adult population.

The 2016 joint position statement on nutrition and athletic performance from the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine, co-authored by Australian sports nutrition researcher Professor Louise Burke, recommends 1.2 to 2.0 g/kg/day for athletes. It also recommends spreading intake as regular serves of about 0.3 g/kg across the day and after exercise.

Do endurance athletes need more protein than older guidelines suggested?

Newer research suggests the upper half of that range is a better target on hard training days. A 2016 study in PLOS ONE used the indicator amino acid oxidation method (a technique that tracks how the body uses a labelled amino acid to estimate true protein needs). It found trained endurance athletes recovering from a 20 km run needed an average of 1.65 g/kg/day, with a recommended intake of 1.83 g/kg/day. Both figures are higher than the 1.2 to 1.4 g/kg/day long recommended for endurance athletes.

How do you calculate your daily protein target?

Multiply your body weight in kilograms by your target. Use the lower end on easy or rest days and the upper end during high-volume blocks, low-carb sessions or when trying to lose body fat.

When do endurance athletes need the upper end of the range?

• High training volume: marathon, Ironman or Gran Fondo build phases.
• Training low: fasted or low-carbohydrate sessions, which increase amino acid oxidation.
• Energy deficit: eating fewer kilojoules than you burn, which makes the body more likely to break down muscle.
• Masters athletes: older muscles respond less to small protein doses, so slightly larger serves help.

When should endurance athletes eat protein?

The best timing is a 20 to 40 g serve of high-quality protein within about two hours after training, then similar serves every three to four hours across the day. The International Society of Sports Nutrition (ISSN) position stand on protein and exercise recommends 0.25 g/kg (or 20 to 40 g) per serve, evenly spaced, and notes the muscle-building effect of exercise lasts at least 24 hours.

Should you have protein before an endurance session?

Yes, as part of your pre-training meal, but carbohydrate should be the priority. A moderate serve of protein two to three hours out, such as eggs on toast or Greek yoghurt with oats, supports recovery without slowing digestion. If you deliberately train fasted or low-carb, early research in the Journal of the International Society of Sports Nutrition is exploring whether a protein serve beforehand helps protect muscle without blunting the training effect.

Do you need protein during long runs or rides?

Usually not. Carbohydrate is the fuel that matters during exercise, and the ISSN recommends around 30 to 60 g per hour for long, hard sessions. According to the ISSN position stand on nutrient timing, adding protein mainly helps when carbohydrate intake is inadequate, where it may reduce muscle damage and support glycogen restoration. Ultra-endurance athletes often include some protein in real-food snacks for this reason.

What should you eat after an endurance session?

Have protein and carbohydrate together within about two hours. The ISSN nutrient timing stand notes that when you need to refuel quickly (less than four hours before your next session), combining carbohydrate at 0.8 g/kg per hour with protein at 0.2 to 0.4 g/kg per hour is a recommended alternative to eating more carbohydrate alone (1.2 g/kg per hour). For a 70 kg athlete, that is roughly 56 g of carbohydrate and 14 to 28 g of protein in the first hour.

Glycogen (the carbohydrate stored in your muscles and liver) is your main fuel for hard efforts. Pairing protein with carbs after training helps restore it faster while repairing muscle at the same time, which matters most when you train twice a day or race on consecutive days.

Is protein before bed useful for endurance athletes?

Yes, particularly during heavy training blocks. The ISSN reports that 30 to 40 g of casein (a slow-digesting milk protein that releases amino acids over several hours) before sleep increases overnight muscle protein synthesis. For endurance athletes, the overnight window is a long stretch without food, so a pre-bed serve helps close the gap.

What is the best type of protein for endurance athletes?

The best protein for endurance athletes is one that is complete, easy to digest and high in leucine (the amino acid that acts as the main "on switch" for muscle protein synthesis). Whey ticks all three boxes, which is why it is the most studied post-exercise protein. Whole foods should still make up most of your intake.

Is whey protein good for endurance athletes?

Yes. Whey is digested quickly and is naturally rich in leucine, so it gets amino acids to working muscles fast after a session. True Protein's WPI 90 is made with New Zealand grass-fed whey protein isolate and contains less than 1% carbohydrate and sugar, so it is easy on the stomach after a long run or ride. Blend it with a banana and oats or mix it into milk to get your carbohydrate and protein in one hit.

If you'd prefer a creamier shake at a lower price per serve, WPC 80 delivers 24 g of protein per 30 g serve and works well in breakfast oats before an early session.

What about plant-based endurance athletes?

Plant-based athletes can meet their needs, but should aim slightly higher and combine sources. Single plant proteins tend to be lower in leucine and some essential amino acids, so blends of pea, rice and other plant proteins give a more complete profile. True Protein's Plant Protein offers a convenient complete option for vegan and dairy-free athletes.

Should endurance athletes use casein?

Casein is most useful before bed during heavy training blocks. Because it forms a gel in the stomach and digests slowly, it releases amino acids through the night. Night 85 or a bowl of Greek yoghurt or cottage cheese both do the job.

What does a high-protein day look like for an endurance athlete?

Here is an example heavy training day for a 70 kg runner doing a 90-minute morning session, targeting about 1.8 g/kg (roughly 126 g). Protein is spread across six eating occasions, with carbohydrate in every one. Protein amounts are approximate.

Notice what this avoids: the common pattern of 10 to 15 g at breakfast and lunch, then 60 g or more at dinner. Even serves keep muscle repair ticking over all day, rather than once.