[Scott Johnston]

Sounds like you do have a strength deficiency. Strength is the base for developing muscular endurance.  With insufficient strength you will be limited in ME development.  The simplest thing will be to include a dedicated strength training block into your program. Winter is the normal time to include this as so it won’t have too much of an impact on high intensity training.  If you are not racing in the new future you can begin to add this in now.  1-2x/wk using a simple max strength training protocol (2-3 warm up sets leading into 4sets of 4 reps @ 90% of 1RM) will help.  Exercises we recommend are: Box Step up 75% of knee height,  Single Leg Romanian Dead Lift, Bulgarian Split Squat.  It will take you a few sessions to figure out the correct weight to use for these. You can also do 1/wk stair bounding sessions.  after a good warm up bound as high as you can till the power drops (sounds like 3-4 bounds for you right now).  When you can no longer reach that high point the workout is over.  Take 3 min rest between reps.  This will seem very long and boring but to develop power you must be able to recruit the fast twitch fibers and they are slow to recover.

I hope the helps,

Scott