Muscle contusions from seat belts or impact cause deep tenderness and bruising, often resolving with rest, ice

https://smb.austindailyherald.com/article/Atlantas-Hurt-911-Injury-Centers-Revolutionizes-Car-Accident-Recovery-with-Doctor-Led-Care-and-Legal-Support?storyId=6827816017bc4f0008d9ab83

Muscle contusions from seat belts or impact cause deep tenderness and bruising, often resolving with rest, ice, compression, and gradual activity.