For a long time, whey protein was associated with gyms and big biceps. However, the recovery needs of a marathon runner, trail runner, or long-distance cyclist are just as demanding.
After a long 2-hour run, a trail run with significant elevation gain, or an intense interval training session, your muscles suffer micro-tears, inflammation, and a significant energy depletion. The question is therefore no longer: “Is whey protein only for bodybuilding?” But rather: “Do I recover well enough to progress? ”
This article reviews the real usefulness of whey protein for endurance sports, answering the questions you ask most often.
What is whey protein?
Whey is a protein derived from milk. During cheesemaking, the remaining liquid is called whey. This liquid is filtered to isolate the proteins, then dried to obtain a powder.
Why is it interesting for an athlete?
When you do a workout (marathon, trail running, cycling, interval training…), your muscle fibers are damaged by microscopic movements. To repair them, your body must activate a mechanism called: muscle protein synthesis.
- Whey contains all the essential amino acids
- It is naturally rich in leucine, the key amino acid for muscle repair. It activates a metabolic pathway called mTOR (simply put: the "control center" of muscle building) at doses as low as 2 to 3 grams. Read the labels of the products you buy carefully!
- Without sufficient leucine, reconstruction is less effective.
- Whey is quickly absorbed (1 to 2 hours)
Unlike meat or eggs, which take several hours to digest, whey is available quickly after exercise.
What are the different types of proteins?
Whey or plant-based proteins for endurance?
Plant-based proteins can be suitable, but they are often lower in leucine, their absorption may be slightly slower, and their taste is sometimes more bitter. Therefore, you will need more of them to achieve the same result.
Whey concentrate or isolate: which to choose?
There are two main forms of whey.
- Whey concentrate: More economical, contains some lactose and is slightly higher in fat.
- Whey isolate: More filtered, almost lactose-free, and more digestible
In endurance sports, isolate is often more comfortable if you have a sensitive gut.
What are the protein requirements of an endurance athlete?
It's often thought that runners only need carbohydrates. That's true, but it's incomplete. International sports nutrition recommendations, particularly those from the International Society of Sports Nutrition (ISSN) and the American College of Sports Medicine (ACSM), indicate that endurance athletes have higher protein requirements than the general population.
While a sedentary adult needs about 0.8g of protein per kilogram of body weight per day , an endurance athlete should aim for between 1.4 and 1.8g/kg/day , or even more during periods of high training load.
Example: A 70kg runner needs approximately 100 to 120g of protein per day .
For what ?
- Repairing muscle fibers
- Limit the loss of lean mass
- Supporting the immune system
- Optimizing adaptation to training
During periods of high workload (marathon preparation, trail running block, cycling training camp), diet alone may not be sufficient to meet protein requirements, hence the benefit of an external source.
When and how should whey protein be consumed?
- The key moment: Within 30 to 60 minutes after exercise, during the metabolic window. This is when your muscles are like "sponges" and best absorb protein.
- The "Total Recovery" tip: For optimal recovery, mix your whey protein with a source of carbohydrates (a banana or honey). The sugar helps transport proteins to your muscles and replenishes your glycogen stores.
- Dosage: A dose of 30g (one scoop provided) mixed with 250ml of water or plant-based milk in a shaker or water bottle is more than enough for a classic session.
The ultimate recovery: combining protein with other dietary supplements?
Protein alone does not provide all the necessary recovery. It provides the building blocks for muscle construction, but for these building blocks to be used effectively, the body needs a favorable environment: minerals, hydration, available energy and support for connective tissues.
Combining whey protein with carbohydrates after exercise, such as energy compotes, helps to replenish glycogen and facilitate the assimilation of amino acids.
Adding magnesium helps reduce neuromuscular fatigue and support energy production.
Supplementing with collagen can strengthen tendons and joints, which are particularly stressed during marathons or trail running.
Finally, proper hydration with electrolytes optimizes nutrient transport and limits post-exercise physiological stress.
In endurance sports, recovery is an ecosystem: proteins are the basis, but their effectiveness increases when they are integrated into a comprehensive and coherent nutritional strategy.
Why is whey protein useful after a long ride?
After prolonged exertion, glycogen stores are low, muscle fibers are damaged, and tendon inflammation is high.
Whey protein acts on three levels:
- Faster muscle repair: It provides the necessary “building blocks” to rebuild the fibers.
- Less muscle soreness: Sufficient protein intake reduces the duration of post-exercise pain.
- Preservation of muscle mass: During prolonged efforts, the body can use muscle as energy if the intake is insufficient.
Should you take whey protein on days you don't train?
Yes, if your regular diet doesn't meet your needs. Muscle recovery continues for 24 to 48 hours after an intense workout. If your daily intake is already sufficient through food, it's not essential. Otherwise, a protein shake can easily supplement your intake.
Whey protein before a workout or race: a good idea?
Whey protein is most useful after exercise , but before an intense workout or competition, it can be taken at breakfast. Avoid it right before a race if you have a sensitive stomach. The main goal before a race remains carbohydrate intake.
Whey and digestion: a crucial point in endurance sports
Many trail runners and marathoners have sensitive digestive systems. Some whey proteins on the market contain artificial sweeteners, very sweet flavorings, and thickening additives. This can cause bloating and discomfort related to slow digestion during exercise. Digestive tolerance is just as important a factor as protein content.
Does whey protein cause weight gain?
No. One serving provides approximately 110 to 130 kcal . It's not the whey protein itself that causes weight gain, but rather an overall calorie excess. On the contrary, sufficient protein intake promotes lean muscle mass.
Is it dangerous for the kidneys?
In a healthy person: no. A high protein intake does not damage the kidneys in the absence of pre-existing conditions. It is simply recommended to stay well hydrated.
Common mistakes with whey protein in endurance sports
- Not consuming enough protein during the day
- Forgetting to combine carbohydrates after a long run
- Choosing a whey protein that's too sweet
- Take it just before leaving if you have a sensitive stomach.
- Neglecting hydration
Which flavor should I choose?
Here are the most common flavors found on the market (with their strengths and limitations from an athlete's perspective):
- Chocolate: A classic and widely appreciated taste that often pairs well with milk or plant-based drinks. It can be too sweet or heavy, especially if artificial flavorings or low-quality cocoa are used. Some find it becomes cloying over time. Sometimes it's too high in added sugar.
Verdict: good for occasional consumption, less suitable if you want to drink it daily after each session.
- Vanilla: Mild, light, not overpowering, and very versatile: blends well into smoothies, porridge, pancakes, yogurt, etc. Its flavor is perceived as more "neutral," making it perfect for frequent consumption. There's less "artificial" sweetness on the palate, which is often better tolerated. Some find vanilla "too plain" if poorly formulated, but when well-balanced, it remains very pleasant.
Verdict: best compromise for regular use, especially for athletes who need to consume whey several times a week.
- Strawberry/Red Berries: Fruity and refreshing profile. Can be pleasant in summer or with cold water. Can taste artificial if the flavoring isn't natural. Less versatile in recipes (best suited for cold drinks).
Verdict: a good choice if you like fruity flavors, but pay attention to the quality of the aromas.
- Coffee/Iced Coffee: Energizing taste when paired with a morning outing. May appeal to coffee lovers. Not always suitable for people sensitive to caffeine. Can become monotonous if consumed too frequently.
Verdict: niche but relevant for certain profiles
- Cookies/caramels: Highly appealing to those with a sweet tooth or a "dessert" craving. They can be too sweet or rich, which may hinder digestion after exercise. Often used as a marketing tool rather than for their functional value.
Verdict: pleasant on occasion, less relevant for a daily nutritional strategy.
Can a meal be replaced by a shaker?
A whey protein shake can be a convenient option, but it doesn't replace a proper meal in the long run. A complete meal provides not only protein, but also fiber, vitamins, minerals, and essential fats. Whey protein is useful for supplementing insufficient protein intake or for rapid recovery after exercise. However, regularly replacing lunch or dinner with just a shake can lead to deficiencies or insufficient satiety. Ideally, whey protein should be seen as a practical supplement, not a permanent substitute for a balanced diet.
Is it safe to consume whey protein in the evening before bed?
Whey is a fast-absorbing protein, making it ideal after a workout. Taking it in the evening before bed isn't necessarily the most strategic time, unless your protein intake during the day was insufficient. For nighttime, a slower-digesting protein (like casein) is often recommended because it gradually releases amino acids over several hours. That said, taking whey in the evening isn't a problem: if your daily protein intake is adequate, it will still have a positive impact on muscle recovery.
Whey and cramps?
Whey and weight loss in women?
Whey protein can be a useful tool for weight loss, including for women. Protein increases feelings of fullness and helps preserve muscle mass during periods of calorie deficit. Maintaining muscle mass is essential for a healthy metabolism. Whey protein won't cause bloating or bulk without specific strength training. For endurance athletes, it primarily helps maintain muscle tone and recovery while controlling overall calorie intake. As always, it's the overall daily energy balance that determines weight loss, not the protein shake itself.
Mulebar's natural approach
In the jungle of supplements, the French brand Mulebar stands out with a "health" approach that is very popular with trail runners and cyclists.
- 100% Natural: No artificial sweeteners (like sucralose) that can disrupt the intestinal flora and cause gastric discomfort.
- Guaranteed digestibility: It dissolves instantly and does not weigh on the stomach, even right after a competition.
- Effective composition: Each 30g serving provides 20g of protein and is naturally rich in BCAAs (the key amino acids for recovery) including Leucine.
- Ethical: Made in France with quality ingredients, it respects both your body and the environment.
Its key advantage is its low sugar content (3.3g per serving) to reduce intestinal stress. During endurance activities, the gut is already under considerable strain. During prolonged exertion, blood flow is primarily directed to the muscles and skin, reducing blood flow to the digestive system.
The result: digestion becomes slower and more fragile. Whey protein that is too sweet, or contains a lot of artificial sweeteners, increases the osmotic load in the intestine. In practical terms, this draws more water into the digestive tract, can accelerate transit, and promote bloating, discomfort, or digestive problems.
Conversely, a less sweet and simpler whey protein is generally better tolerated, especially by trail runners and marathoners who train frequently. Less added sugar often means less fermentation, less irritation, and therefore less intestinal stress—a key factor when recovery needs to remain comfortable and effective.
The goal is not to "bloat", but to recover effectively without disrupting the intestines.
A simple strategy to prepare for a marathon or trail run
Example :
- Long ride → whey + carbohydrates immediately afterwards
- Intense workout → whey protein within the hour
- Day off → high-protein diet
- Loading period → special attention to total daily intake
Progress depends on your ability to recover. In endurance sports, consistency is key. Whey protein is a simple, practical, and effective tool to support this consistency.
Key figures reminder:
| Indicator | Recommended value | Why this is important |
|---|---|---|
| Protein intake for sedentary adults | 0.8 g/kg/day | Minimum requirement for the general population |
| Protein intake for endurance athletes | 1.4 to 1.8 g/kg/day | Muscle repair + adaptation to training |
| Post-workout benefits | 20 to 30g of protein | Optimizes muscle protein synthesis |
| Leucine threshold | 2 to 3g | Activates the mTOR channel (triggers reconstruction) |
| Muscle reconstruction time | 24 to 48 hours | The muscle continues to repair itself after the session |
| Caloric intake of a shaker | 110 to 130 kcal | Minimal impact on weight gain |
| Ideal sugar content (endurance whey) | ≤ 3–5g per serving | Better digestive tolerance |
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