In the first blog on sprinting we spoke about acceleration performance. In this blog we will look at maximal speed sprinting. This is your ability to run at your fastest speed possible.
Luckily through the IAAF biomechanics research projects, we have some amazing data that shows what makes the best in the world run really fast. Ultimately with top speed, that is velocity in m/s is determined by two factors. Stride length multiplied by stride frequency. It seems simple but it is these items that then need to be broken down further. When we think about stride length it is ultimately influenced by two key factors. The height of the athlete (more specifically their leg lengths), and the ground reaction force that they apply to the ground. The research by Weyand and Clark highlights that ground reaction forces at top speed are as high as 5 times our body weight and occur in as little as 0.08 seconds. We add this to the information supplied by JB Morin and his group and we come to the conclusion that if you can hit the ground hard, rapidly and in the correct direction, you are likely to develop the necessary ground reaction forces to have a sufficient stride length. The forces that you see in the ground reaction force are a combination of muscular input and stored elastic energy created in the leg when you land with a stiff and stable leg and ankle. Measurement of elite performers at the 2017 world championships showed that stride lengths are typically between 1.3-1.35 x height in males and 1.25-1.3 times height in females.
Stride frequencies tend to vary once again on the height of the athlete, this is due to the balance between the stride length and stride frequency equation. If you have a very long stride length, such as Usain Bolt, you do not need an extremely high stride frequency, however shorter athletes will require much higher frequencies if they cannot create sufficient stride lengths to match taller athletes.
How do we do this?
The area that is always discussed in reference to stride frequency is the ability of the athlete to exchange their legs; this can be done in two ways. Actively, and actively with reflex assistance. Active exchange is the physical movement of their legs by the athlete, if it is completely conscious and driven by the muscular system alone, it is likely to be insufficient to achieve world class frequencies (as high as 5 steps per second). The use of the cross extensor reflex (the reflex that occurs when we quickly pull up or push down our leg) causes the opposite limb to reactive reflexively, allowing athletes to use their neurological system to evoke a reflex, reduces reliance on muscular structures and aids with the speed at which we can exchange our limbs.
So how do we run faster?
As suggested in theory we need to hit the ground hard, on a stable/stiff leg, very rapidly and in the right direction, whilst switching our legs reflexively. It sounds complicated, and that is why running faster requires significant practice. To assist in this process using technical drills such as dribbles (cyclical running that aids with ground contact stiffness and switching), and running over mini hurdles or cones (allowing for manipulation of stride length and frequency) can be useful. Obviously exposure to maximal sprinting repetitions will assist with practice then if required the use of assistance (downhill, wind or pulley system) all allow the athlete to learn to move themselves across the ground faster.
We hope you enjoyed this blog series. If it was of interest to you we will be running a sprint mechanics workshop on April 14th. To book your place register here.