Hi BernieWal, if your body is used to training, get out and do it. You will know when you need to back it off. You know your body.
I am a Masters Racing Cyclist (with a few Aussie age titles under my belt), diagnosed last August (after 3 mths riding every hill in France&Italy) had a 3cm tumour, mastectomy, back riding after 2weeks, 1 micro met in closest sentinel node, rest all clear, oncotype dx on tumour was a low score so didn’t need chemo, but had to do 5weeks radiation. I live in the country and had to travel to a regional Cancer centre, 3hr round trip daily. I did get fatigue and major skin issues, but still rode everyday, whether intervals indoor on a smart trainer, or at least 50km on road. Hill climbs and longer rides on the weekends. The real fatigue set in 4 weeks after the radiation finished, around end of December, it surprised me how smashed I felt, but still got out to ride, even if it meant doing nothing else for the rest of the day. Probably middle of March I started to get my mojo back, and now back into full training. I do take arimidex, but don’t notice any side effects because I keep myself moving and active. I trail hike 3x weekly for a bit of cross training and weight bearing.
As they say Motion is Potion, it’s true, keep up your running, it’s your happy place, releasing all those good endorphins that will help with your recovery, and thru the Chemo. Take care 😊