Eccentric is the lengthening phase of a movement, where most soreness and most strength adaptation come from.
Lowering a weight, landing a stride, the down of a squat. In 📝Sports Therapy a week with a lot of eccentric work often means more DOMS and a different table dose. The word is a training fact, not a diagnosis, and not a claim that eccentric work treats a tear. Sharp or worsening pain follows the 📝referral rule.
Clients feel the delayed ache after new lowering work. That ache is expected; sharp pain is not.