So I think doing intervals may have somewhat damaged my stamina.
I used to be able to run consistently for 35 minutes on treadmill level 10.5 (or for about 50 minutes giving myself a 30 second break every so often).
But since doing intervals I struggle a lot to do more than 15 minutes on treadmill level 11.
If I’m doing intervals I can go for a decent length of time varying between levels 13, 11 and 6 on breaks.
I want to build stamina again so should I start alternating my interval days with consistent run days????