How Running Affects Your Bones
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Why Bone Health Matters for Runners
If you love running long distances, your bones go through a lot. Every time your foot hits the ground, your skeleton absorbs force—2 to 4 times your body weight, in fact! Over time, this constant pressure can lead to small cracks in the bones, known as bone stress injuries (BSIs). These can turn into stress fractures if not managed well.
BSIs are common in runners, especially those with low energy availability—when you're not eating enough to match the energy you use during exercise. To avoid these issues, it's important to understand how running affects your bones and how nutrition—especially protein—can play a role in keeping them strong.
What Happens to Bones During and After a Run
When you run, your bones respond in two ways:
- Bone Resorption – Your body breaks down old or damaged bone tissue.
- Bone Formation – Your body builds new bone tissue.
This balance is known as bone remodeling. After a tough run, your body increases bone breakdown (resorption), which can last for a few days. If you don’t rest and recover properly, the breakdown might outpace the rebuilding process, weakening your bones over time.
The Role of Inflammation
Exercise, especially long or intense sessions, also triggers inflammation—a natural process where your body repairs itself. After a run, your body increases certain inflammatory markers like IL-6 and TNF-α. These help with short-term recovery but can become a problem if they stay elevated due to constant training with little rest. Chronic inflammation has been linked to weaker bones in endurance athletes.
What Are Osteokines?
Osteokines are proteins made by bone cells that help regulate bone health. One important osteokine is sclerostin, which tells your body to slow down bone formation. After long runs or races, sclerostin levels can stay high for days, possibly leading to more bone breakdown than buildup. Other markers like RANKL promote bone resorption, while OPG helps protect against it.
How Protein Might Help
Protein is well-known for supporting muscle repair, but it also plays a key role in bone health. Here’s how:
- Promotes Bone Formation: Protein helps build the collagen matrix that makes up much of our bones.
- Balances Bone Resorption: Some studies suggest protein can reduce the breakdown of bone after exercise.
- Reduces Inflammation: High-protein diets may lower pro-inflammatory markers and raise anti-inflammatory ones like IL-10.
- Boosts Calcium Use: Protein helps your body absorb calcium better, which is essential for strong bones.
When to Eat Protein for Bone Health
Researchers have explored different timings for protein intake:
- Post-Exercise: Having protein (especially with carbs) after exercise may reduce inflammation and bone resorption.
- Pre-Exercise: A protein-rich meal before a workout may also help, though results are mixed.
- Habitual Intake: Athletes who eat more protein daily tend to have better bone health than those who don’t.
What We Still Don’t Know
Although there's promising evidence, more research is needed—especially studies focusing specifically on endurance runners. Most findings come from other athlete groups or general populations. It’s still unclear how much protein is ideal, or which type (whey, casein, collagen, etc.) is best for bones.
Simple Tips for Runners
- Eat Enough: Make sure your calorie intake supports your training.
- Include Protein: Aim for a protein-rich snack or meal after long runs.
- Don’t Skip Rest Days: Recovery is when your bones rebuild.
- Watch for Warning Signs: Persistent pain might mean a bone stress injury—don’t ignore it.
Final Thoughts
Running is great for overall fitness, and it can even improve bone strength over time. But if you’re logging a lot of miles, your bones might need some extra support. Protein isn’t just for muscles—it could help keep your bones healthy and reduce injury risk. Eating well and recovering properly is key to staying strong and injury-free on the run.