Heavy Legs While Running: Why It Happens (And How To Fix It)

Why do your legs suddenly feel heavy during a run—even when your fitness is improving?

This is one of the most frustrating and misunderstood experiences in running. One minute you feel smooth and in control… and the next, your legs feel like bricks.

This episode is grounded in exercise physiology and real-world training principles.

In this episode, Coach Chris and Coach Maya break down exactly why this happens—and how to fix it.

We cover:

• ⚡ How glycogen depletion impacts muscle force and perceived effort
• 💧 Why electrolyte imbalance (especially sodium) disrupts muscle contraction
• 🧠 The role of neuromuscular fatigue and the brain’s “central governor”
• 🔧 A simple system to prevent heavy legs before, during, and after your runs

🔗 Start Here: The Injury-Proof Half Marathon System
Download our free 14-week training plan and learn how to structure your training, fueling, and recovery: halfmarathontrainingplan.com/start

📚 Learn More:

• How to Avoid Shin Splints
• Fueling Long Runs
• Electrolytes for Runners

This has been a production of the Half Marathon Training Plan Podcast. Visit HalfMarathonTrainingPlan.com for more science-based training guidance.