Is this 100lbs or kgs? In either case, it sounds like more max strength work would be helpful. Keep the reps low and work on the endurance at the track.
I had planned to do a Hypertrophy phase with higher reps during GPP next season. I won’t take reps as high as 15 though, 10 at most and mostly 6-8 for the phase.
David W has, though, planted some seeds of doubt in my mind!
Where doubt exists I usually leave the last word to Charlie:
“I think there is an issue outside of the normal lifting parameters for sprinters due to the special endurance qualities. I agree that in most lifting scenarios, a 5 and under approach is effective and that weights shouldn’t be used for strength endurance objectives, but higher numbers can be used- and, in the case of at least 2 sub 9.80 sprinters, have been used for brief periods. BTW, with Olympic lifts, we didn’t exceed 6 reps.”
I will also go upto 10 reps/set in the GPP. However, I have noticed that if I do 3-4 sessions of 15 reps/set before our repetitive 200, 300 or 400 sessions begin, I cope better. I feel its like this - 15 reps (compared to 5/10 reps) do not help an idividual 200m race, but they improve 200/300/400m sessions, which in turn help the 200m race.