4. A Few Unexplained Kilograms May be a Red Flag

Because many runners are leaner than the general population, doctors may let them off the hook if they gain a little weight. But if you put on a few kilos despite your activity levels remaining constant, alert your doctor. Unexplained weight gain might be a red flag for a condition like sleep apnea or hypothyroidism. Additionally, because gaining weight means you hit the ground with more force with every step, putting you at a higher risk for injury, you might want to address the cause, even if it’s an unnoticed change in diet and not a serious medical issue.

READ MORE ON: injury-prevention