How Endurance Exercise Affects Protein Use in the Body
Share
Introduction
When we think of fueling the body during exercise, we often talk about carbohydrates and fats. But there’s another important player in the mix—protein. While protein is usually associated with muscle repair and recovery, a new review shows that it also plays a small but important role in energy production during endurance workouts. Let’s explore how protein behaves when you’re running, cycling, or training for long hours.
Protein Isn’t Just for Recovery
Most people believe that protein’s role begins after a workout to help with muscle recovery. While this is true, the body also breaks down some protein during exercise itself. According to a large review of over 30 studies, endurance training leads to a noticeable increase in protein oxidation. This means the body starts using more protein as fuel, especially when exercise is intense.
Even though protein’s contribution to total energy during exercise is small—around 3%—it still matters. The amount of protein broken down during a typical endurance session is enough to impact overall muscle health and performance if not replenished properly.
Intensity Matters More Than Duration
Interestingly, the review found that exercise intensity has a bigger effect on protein breakdown than how long or how much you exercise. In other words, the harder you push yourself, the more your body may dip into its protein stores for energy—even if the session isn’t super long. However, if you go on a long but easy-paced workout, protein use doesn’t increase in the same way.
Why This Matters for Athletes and Regular Exercisers
This matters for anyone doing regular endurance workouts—like runners, cyclists, and triathletes. While the bulk of your energy still comes from carbs and fats, ignoring protein needs during training could hurt performance and recovery over time. If the body doesn’t get enough protein through food, it may break down muscle to meet energy demands, which is not ideal.
Tips to Support Protein Needs
Here are a few simple strategies to make sure your protein needs are covered:
- Eat enough daily protein: Especially on training days, aim for 1.2–1.6 grams of protein per kg of body weight.
- Include protein in post-workout meals: This helps with muscle repair and supports recovery.
- Balance carbs and protein: Adding carbs during long or intense exercise can help reduce how much protein your body breaks down.
Stay fueled: Avoid training on an empty stomach if you’re doing long or high-intensity workouts.
Conclusion
Protein may not be your main fuel source during endurance exercise, but it still plays a role in keeping your body performing at its best. Intense workouts increase the need for protein, and if you don’t eat enough, your muscles may pay the price. So whether you're training for a race or just enjoy long rides or runs, don’t forget to include enough protein in your day. It could be the difference between staying strong and wearing out.