Understanding proper hand placement in the four-point start is being tested here. When the hands are too wide, the root issue is a misunderstanding of how the start setup should be arranged for an efficient first move. The hands should be under the shoulders, roughly shoulder-width apart, with the body aligned in a straight line and the weight balanced over a stable base. If the hands are spread too far, the setup becomes unstable, the center of mass shifts outward, and it hinders a powerful, quick drive forward. This issue points to how the start is supposed to be positioned rather than to weight distribution, hip height, or knee bend, which affect other aspects of the sprint but don’t directly explain why the hands end up too wide.

At max-sprint speed you want the ground reaction force to push you forward rather than lift you up. When the push-off is directed too vertically, most of that force goes into raising the body's center of mass rather than driving it forward. The result is a pronounced vertical bounce and a swaying of the body with each step, which wastes energy and reduces forward velocity. That’s why a vertical push-off best explains the described pattern. Inadequate knee drive would limit forward propulsion but doesn’t inherently cause the repeated vertical bouncing. Slow arm swing can affect tempo and coordination but isn’t the primary driver of vertical oscillation. Foot strike too far in front of the center of mass tends to create braking, hindering forward progress rather than producing the vertical bounce seen at maximum velocity.

Speed in sprinting comes from a balance of how often you cycle your legs and how long each step is, while the energy should be directed forward rather than upward. So the goal is to have a high stride frequency and an optimal stride length, with an explosive horizontal push-off and minimal vertical impulse. The set that fits this description is high stride frequency; stride length; horizontal push-off; vertical impulse. It mirrors first prioritizing rate and length, then the direction of force application, and finally reducing vertical motion for efficiency. Other orders shift the emphasis in a way that doesn’t align with the stated goal.

During sprinting, the leg that is in contact with the ground goes through both braking and propulsion within the same stance phase. When the foot lands, the muscles work eccentrically to absorb force and slow the body's forward momentum (eccentric braking). Almost immediately, they switch to concentric action to push off and propel the body forward for the next step (concentric propulsion). This sequence happens during the single-leg support portion of stance, when one leg is bearing the body's weight. The other phases don’t involve this combination. The flight phase has no ground contact, so there’s no braking or propulsion, and the recovery or swing phase is the leg moving forward in the air. Start in sprinting refers to beginning acceleration from blocks, which isn’t the continuous stance where braking followed by propulsion occurs.