Heat therapy works on the principle of increasing blood flow to the affected area, promoting relaxation of the muscles and reducing stiffness. When applied to the back, a hot pack bag can help in several ways. The warmth penetrates deep into the tissues, alleviating pain associated with muscle strain, chronic conditions like arthritis, and even injuries. For many individuals, the soothing warmth of a hot pack can be comforting and can significantly improve their day-to-day comfort level.