noun
post-massage muscle soreness; rebound pain from massage
Refers to muscle pain or stiffness that appears after a massage, often the next day, as a reaction to the pressure applied.
昨日マッサージを受けたら、今日は揉み返しで肩が痛い。
I got a massage yesterday, and today my shoulders hurt from the rebound soreness.
揉み返しがひどくて、首が回らない。
The post-massage pain is so bad I can't turn my neck.
筋肉痛 is general muscle soreness, often from exercise. 揉み返し specifically refers to soreness caused by massage.
Compound of 揉み (momi, 'massaging', continuative form of 揉む) and 返し (kaeshi, 'returning', continuative form of 返す), literally 'massage return'.