There I was, 10 weeks post AVR, feeling good, no painkillers. Then I got complacent. I returned to my singing group and joined in the singing for a couple of hours. It didn't hurt particularly at the time, but boy have I paid for it in the following days! My sternum feels sore and intercostal muscles feel strained, so I'm back on paracetamol.
The advice? Don't get complacent, start gently and build up! Who knew singing was so strenuous!