Muscle fatigue at the end of the day is a completely natural process, especially if the day involved heavy physical labor. Most often, fatigue causes pain in the lower back, arms, and legs. But there comes a point when a person begins to notice lower back pain even at rest; the pain intensifies when walking, radiating down the arm or leg. Bending over becomes increasingly difficult, and relaxing the back muscles becomes virtually impossible, even when lying down.
