I run about 60 mpw and my runs are usually 6:4x pace. They used to be faster during the track season but I've slowed down for more quality. My training just consists of a long run, a solid 20-minute tempo(5:2x pace), and a short hill workout every week on top of "easy runs". For the past month, I've been biking to and from work for about 40 minutes daily and I ride around 16-17 mph. My heart rate barely passes 130 bpm but lately, I have been exhausted keeping up my training regimen. Heart rate data shows I'm getting fitter but the legs have been beat up for a while now. Anyone else felt the same? I only use to bike to cross-train but combining with running just leaves my legs confused.