Hitting this one (beautiful) inside-out forehand gave me an immediate pain in the chest/heart area that required me to retire from the hit, so I guess this was my first ever retirement due to injury. I was unable to bend/stretch/turn without extreme tightness in the chest + rib area. I’ve had this pain before from sitting or lying down, but never caused directly by a physical movement. The Cleveland Clinic’s information on intercostal muscle strain is the closest thing I could find to what this is. Hopefully ice + the hot tub can get me a quick recovery!