Final answer:
The area becomes red and puffy after applying friction to a muscle due to the release of histamines.
Step-by-step explanation:
After applying friction to a muscle, the area may become red and puffy due to the release of histamines. When tissue is injured, damaged cells release inflammatory chemical signals that cause local vasodilation, widening the blood vessels, which leads to increased blood flow and apparent redness. Mast cells release histamines, which are potent vasodilators and contribute to the redness and heat. Additionally, inflammatory mediators and increased blood flow cause swelling, resulting in the puffy appearance.