"It has been shown in high-speed motion analysis studies that too much time in the air and too much time on the ground hinder summative velocity in a runner. Time on the ground is regulated by stride rate. Time in the air is regulated by stride length. Studies by scientists have shown that for both sprinters and distance runners: reducing contact time, thus improving stride rate, is the key to improving performance. For a distance runner to reduce contact time by .02 seconds per stride would lead to marked improvement at any distance. The chief biomechanical means for achieving this reduction is to shorten the stride length, thus reducing braking forces."
The main study is the Harvard university study (circa 2000) conducted by Professor Weyand that concluded the average sprinter's time in the air is not much different from an elite level thlete. They found that ground contact, ie: the athlete's ability to apply greater support forces that contributed to an athlete's capacity to run faster.
The issue since this ground breaking research in 2000 has been what training methodologies are available to assist the athlete's ability to create a greater force so as to lessen the ground contact time. There are numerous theories about how this can be achieved and it's still inconclusive to pinpoint a specific exercise that categorically improves this.
To see the study paper, click below:
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