I am asking about a National Champion Dog Agility Competitor wishing to improve her sprint mechanics. Through corrective exercise and conditioning she has greatly improved her athletic performance. She wants to correct her posture when sprinting a straight line at the end of the course for more acceleration/speed.
Sprint mechanics are important to master at all levels of competition. As long as the athlete’s foot contacts are correct( ball of the foot is the only contact, feet are positioned straight ahead, triple extension is achieved during late/push off phase), then start training the athlete with starts. Powerful starts are a key to achieving acceleration and a good position during the first phase of the race. Have the athlete get into a crouched position( center of mass is almost vertical to the ground, one foot is straight back behind the torso, the other foot is under the chest, arms are in front of the body, and there is a forward lean. When an athlete is in the start position, they should learn to fall forward at the synchronized time when the race is signaled to start. At the start signal, the athlete needs to powerfully push off their back foot and start to fall. As they feel their bodies falling the front foot will catch them in a position in which the leg has taken a long stride forward. You are almost teaching your athlete to do a one legged hop/skip off of the starting line. They should almost feel like they have done a broad jump with one leg. I would have your athlete practice starts in increments of 20, 40, 60 yards to try to master the “jumping” starts to develop a powerful start. This will aid in motor development in acceleration. Keeping a forward momentum and a feeling of “falling forward” will help the athlete maintain their speed and decrease breaking forces that come from erect torso positioning and leaning backwards during periods of accelerating.