🚦Speed Development includes many variables, however one of the most important would be ROFD or Rate of Force Development
One way to train ROFD is by using medium to slightly heavy weight with an explosive concentric.
The concentric portion of this movement would be stepping up onto the box.
By generating as much force and being as explosive as possible on the way up, you will train your body to be more explosive and increase it's ROFD.
This has a carry over to the field and will make you a much faster and more explosive athlete.
Chains are an added bonus because they require you to be even more explosive as they add weight to the bar as your rise up when compared to just using a regular loaded barbell
Moral of the story.....train to improve ROFD and watch your speed and power sky rocket 🚀