quad heaviness on longer tempo efforts?

I also have considered it may be a biomechanics related issue. If I run at a pace faster than easy pace (let's say 7:15 as a random number), I often notice small amounts of the same type of leg heaviness. Particularly so if I don't ease into the pace, like when I am running in a group.

Whenever I’ve had this happen ive had low iron levels. Maybe do labs and supplement if low. It could also just be nutrition going into the run (if you run fasted or are just under fueled generally.)

You need to take an ice bath the night before your next race.

Strengthen your posterior chain. Your quads are working too hard which means your hamstrings and glutes aren't working hard enough.

Get in the gym and start doing glute activation exercises followed by heavy weights such as leg press, squat, deadlift.

I believe you just explain relatively normal fatigue. If you run below lactate threshold you should in theory be able to do that until the glucogen is depleted and that should theoretically happen around 1 hour. I guess your tempo is slower than LT pace so you should be able to do it for longer. But, other factors come into the picture when we run long enough even eventually at an easy long run pace that in theory could be sustained forever (due to fat burning). But we all will eventually be fatigued at any pace.

I think you just experience the effect of training, first getting tired and then adapting to be a little bit better, hopefully

What kind of pace are these being done at? You're using tempo & uptempo interchangeably. Something like 8-10 miles should be done at approximate marathon pace. Use your half to figure out what that pace should be. There's no point going over 8-10 @ M if your longest race is a half. That's plenty. It's also not a workout you should be doing weekly. Maybe once a month or once every 6ish weeks. 2-3 times in a 12ish week half marathon build. Maybe you're doing them too often. Maybe it's a fueling problem (before/during). Maybe it's muscle imbalances or form like others suggested (strengthen glutes/hamstrings/hips, make sure you run with a slight forward lean, etc).

Another idea, until these efforts feel more routine, is to break up the repeats. 3 x 3 miles @ M, 4 x 2 miles @ M, 4-3-2-1 x mile(s), starting @ M, progressing to T, 2 x 4-5 miles, etc.

On the 3x3 and 4x2, how much rest? I may do these for my next block (not this one, I'm not going to go crazy on my taper).

I did 8 @ MP (7:33-7:36-ish) and felt strong, with a last mile at 7:25. And on top of 10 steady @ 8:20-8:10 at first, no rest break.

Weekly mileage?

Yes definitely a biomechanical issue. I've dealt with this multiple times with athletes. We found that really focusing on landing under center of mass and focusing more on pulling with the glute/hamstring resolved this issue in a short amount of time. Quads are doing most of the work. It actually got to a point with them where their quads were actually in pain.

Depends on your pace/goals for the session. You could do 1 mile or less for the 3 mile reps & 2:00-4:00 (1/4 to 1/2 mile) on the 2 mile reps. 8-10 x mile @ T off of 1:00. Generally short rest for these types of sessions. Just giving you a mental break really. Maybe a little more rest if you're going for threshold instead of marathon pace.

NERunner03533 wrote:

Depends on your pace/goals for the session. You could do 1 mile or less for the 3 mile reps & 2:00-4:00 (1/4 to 1/2 mile) on the 2 mile reps. 8-10 x mile @ T off of 1:00. Generally short rest for these types of sessions. Just giving you a mental break really. Maybe a little more rest if you're going for threshold instead of marathon pace.

Thank you! Trying to lock into MP/pacing and these workouts will help.