Why do my legs feel trashed and I feel like I'm struggling when I run 6 miles at a steady pace vs doing 6 miles at varying speeds, even if I average around the same pace for both runs?
Why do my legs feel trashed and I feel like I'm struggling when I run 6 miles at a steady pace vs doing 6 miles at varying speeds, even if I average around the same pace for both runs?
Maybe because with a steady run you make one muscle fiber tired. And with the different speeds you use slowtwitch, fast twitch, intermediate. That's my guess, but I'm no expert either.
You are going too fast on steady states. Steady states are the least demanding of high-end aerobic workouts. In fact, they could be done multiple days in a row if you do them correctly. A lot of East Africans will have runs that end rather fast. They actually end up being locked into steady state during these runs.
My advice: do these steady states at what you feel like is marathon effort. 6 miles is honestly too short if you also do another workout at 6 miles in length. Steady states are long for a reason. One of these reasons is to make you overly cautious so you run the correct effort. It's probably a slower "pace" than you thing.
Source: Division 1 coach and former athlete (trying to get back again)