Isn't TI strength training?
aged (nearly 62) just between Andy, Grand and Richardsk, happy to find time 3-5 times per week for 30-45min swimming, I have a permanent tiny muscle soreness all over the time. My othopaedist says: Fine for your spine!
Never did any special special strength training. So I feel swimming TI (or at least trying it) is strength training by itself, isn't it?
But what I watch with sadness: Recovery time after a gap of one or more weeks takes longer every year. (Just started after 5 weeks off the pool, argh...)