No my question wasnt about mechanics. Im meaning to say if you do a resisted acceleration sprint (up to 30m) , then switch to a flying sprint which is max velocity, or a 60m sprint. Wont the contrast “effect” only be good for acceleration only WITHOUT the resistance, and not have an effect on top speed contrasting.
EDIT: I dont have a sled/tire, so I wanna use a dumbbell or plate + belt/rope, any thing i can do to keep it on the ground without it lifting up? since its only 10-15 pounds. 