Sudden leg weakness could be a sign of a serious medical issue, such as a stroke. Head to the nearest emergency room or call 911 if you're not sure what's going on. Other conditions can also cause leg weakness or difficulty walking.

Why am I feeling weakness in my legs?

Your legs may feel tired or fatigued if your blood isn't circulating through your body properly. Poor circulation often affects the lower part of your body since it's harder for blood to flow upward toward your heart. Sometimes blood can collect in your legs, ankles, and feet.

What deficiency causes weakness in legs?

Muscle weakness due to vitamin D deficiency is predominantly of the proximal muscle groups and is manifested by a feeling of heaviness in the legs, tiring easily, and difficulty in mounting stairs and rising from a chair; the deficiency is reversible with supplementation (15–18).