Muscle weakness and pain, often referred to as myalgia, can result from various causes ranging from overexertion and injury to underlying medical conditions. Overuse or strain from intense physical activity is a common culprit, leading to microscopic tears in muscle fibers, which can cause discomfort and weakness as the muscles repair themselves. Medical conditions such as fibromyalgia, myositis, or electrolyte imbalances can also contribute to persistent muscle pain and weakness. Additionally, deficiencies in essential nutrients, particularly vitamin D and calcium, can impact muscle function. Proper diagnosis and management, including rest, physical therapy, and addressing any nutritional or medical issues, are crucial for alleviating symptoms and restoring muscle strength and function.