Muscles work by contracting and relaxing, and magnesium is essential for this movement. When magnesium levels are low, muscles may struggle to relax after contracting, leading to cramps, stiffness, or soreness—especially after physical activity. Magnesium allows muscles to release tension smoothly, speeding up recovery and reducing the risk of injuries. This is especially important for active children who run, play sports, and engage in physical activities daily.