Acceleration Blog

There are four primary factors that the S&C coach can do to improve an athlete's acceleration

1. stride rate

2. lower body strength

3. upper body strength

4. core stability (anti-rotation)

1. Stride rate

While stride length is the primary determiner of speed, acceleration is mostly driven by foot speed ("stride rate"). 

2. Lower body strength

The relatively longer ground contacts and slow rate of force development during acceleration mean that peak forces are more important to acceleration than RFD.

I think about this by thinking about rowers. When a rowing race starts, the athletes have very slow pulls. This is because they have to get the boat moving from a stationary start. With such a long duration, they have a long time to build to peak force. Once the boat is moving at speed, the oars spend less time in the water because the boat is moving so fast. With so little time in the water, the RFD must be much faster. 

So peak force matters most for acceleration; RFD matters more for speed.

3. Upper body strength

Yes, there's a reason 100 m sprinters have such jacked upper bodies! While the legs drive the ground back, the arms propel the body forward. And for all the force the legs develop, the core and upper body must act as a counter force. 

4. Core stability (anti-rotation)

If the left leg is driving back, and the right arm is driving forward, what stops the whole system from twisting? The core!

If you're watching inexperienced athletes sprint, try watching them from behind. You can recognize a poorly conditioned core because the hips are facing one way while the shoulders are facing the opposite. Their while system is twisted resulting in a running part that is not straight.

While body position is a key consideration for sports coaches when addressing technique, core control is also paramount to the athlete’s ability to stabilise and control motion whilst being subject to high forces, typically in the transverse and frontal planes. Think of the core musculature as an anchor that acts as a fixed point within the body’s centre of mass, creating "anti-rotation". The immensely powerful legs + shoulders can't work together if the bridge between them (the core) isn't stable. 

In the video below, Michael Johnson, a former Olympic champion and world record holder in the 200 m and 400 m sprints talks about some of the biomechanics of great sprinters. At around 1:30 into the video he highlights his economy of movement, in part driven by his rather upright but very stable trunk position. Later (around 5:45), he looks at Usain Bolt, explaining key flaws in his technique, including inefficient core control and required counter-movements that make up for some other technique flaws in the first part of Bolt’s race.