Calcium plays a vital role in bone health and fitness by building and maintaining strong bones. It is essential for proper development during childhood and adolescence, reducing the risk of osteoporosis later in life. Calcium also aids in muscle contraction and nerve function, making it crucial for overall fitness. Dietary sources include dairy products, leafy greens, and fortified foods. Adequate calcium intake, along with vitamin D, ensures optimal absorption, promoting a robust skeletal structure necessary for physical activity.