This is a bit more of a training question than strictly a power one, so if it should be elsewhere let me know.
After some time off work over winter when I was able to put in some miles, my endurance was good. However, work over the last 8-10 weeks has been all consuming with 65/70 hour weeks the norm. Work is also stressful, so sleep has been poor too.
Obviously, training time has been hit and I'm lucky if I've got the time or energy for a Sunday club run. I'm just about keeping fit with the daily commute, but longer rides are noticeably harder in terms of endurance and it's this I want to focus on getting back as quicky as possible.
My question is: What's the best riding, in terms of best bang for buck, to get me back to strong endurance again? Lots of 1-2hr tempo sessions? Longer 3-4hr zone 2 rides?
Thanks in advance.