My physio suggested fartlek - I would have asked what it was but she wrote it down and I didn't read it until after the following...
After 5 weeks out I went on my second return outing today. I do a parkrun circuit as my house is actually on the path that the parkrun covers. It's a hilly course and I divided it into sections and alternated run/walk like this - round the field, run; up the slope, walk [it just worked out that way, honest!]; up the hill, run [stagger!]; along the top, walk; etc. So I did 5k and was out for 45 minutes - at the end I had a niggle in my knee and other ankle.
I then did my exercise routine from the physio and read the 'fartlek' word again. Ignored it - it was obviously something too advanced for me or something I was already doing. Or even her bad handwriting...
Just looked it up now - am working from home so any excuse to slack off is welcome - only to find I have been fartleking by accident! Am well chuffed! And ankle/knee both fine - just a bit of backache!
Here's to fartleking!