4 reasons I use chain resisted sprints to train the 40 yard dash? 1️⃣ Teaches horizontal force production Forces athletes to push the turf instead of spinning their wheels. 2️⃣ Reinforces proper shin & body angles Chains punish early pop-up and reward correct drive-phase positions. 3️⃣ Self-regulating resistance Light early, heavier as velocity increases-matches true acceleration demands. 4️⃣ Improves first-step & 0–10 efficiency Targets the most important part of the 40: the start and projection phase