Take short steps during acceleration?
When I was young, I remember being told to take short steps to have greater acceleration. I still see this being taught, and I see kids trying to take small steps in acceleration. I tried it when I was young and it felt awkward. I didn’t understand how it was supposed to help. I think this is an instruction that people learned, never questioned, and then taught to others. I think the intent is to prevent reaching or over striding, but when a novice hears this, they shorten their steps. Trying to shorten your stride in acceleration will prevent full extension of the trail leg. This shortens the time that horizontal force can be generated to move the body forward, and therefore will decrease acceleration.
You will have a shorter stride length during acceleration, but it is just due to your lower velocity. It happens naturally and you don’t have to try to have a short stride. If you always contact the ground under your hips or center of mass, then the stride length should only be determined by your velocity and how far your body travels in the air. You want to travel as far forward as possible in the air while the legs are scissoring. If you try to lengthen your stride
by reaching and landing ahead with the foot, then you will be braking, or, at best, slowing your stride frequency.
To keep it simple, just drive the knee forward as long as possible allowing the trail leg to extend. Then scissor the legs by pulling the lead knee back with the glutes while pulling the knee of the trail leg forward simultaneously. It is very important that both happen at the same time. The legs should meet under the body at ground contact. In a video, look for the knee of one leg aligning vertically with the other foot at ground contact.