10 Common Mistakes That Make Your Legs Feel Heavy When Running If your legs feel like concrete 10 minutes into your run, you’re probably making one (or more) of these mistakes… 1. Not warming up properly – A few leg swings isn’t enough. Get the blood flowing and activate the right muscles. 2. Going out too hard – Starting fast ruins your rhythm and floods your legs with lactic acid early. 3. Lack of electrolytes – You’re sweating out salt, not just water. Rehydrate properly or your muscles will cramp and feel sluggish. 4. Not fueling right – Running low on carbs = running low on energy. 5. Poor sleep – No recovery = no chance your legs bounce back for performance. 6. Overstriding – Longer strides = more braking forces. Your legs are working overtime to stop your own momentum. 7. Running too often without recovery – Junk miles with no purpose do more harm than good. 8. Neglecting strength work – Weak glutes, hamstrings, and calves = heavy legs that can’t handle volume. 9. Wearing dead shoes – Your legs are absorbing all the impact if your shoes are cooked. 10. Ignoring mobility – Tight hips, quads, and calves restrict movement and create resistance every step. Fix these, and you’ll feel lighter, faster, and fresher on your runs.