You can think of the elastic tissues in our lower limbs as strong elastic bands. When you stretch and then release an elastic band it pings back and stings your fingers! It does not matter how much you stretch the band (unless it snaps) nor how long you hold the stretch for – it will still ping back.
Unbeknown to many runners, the calf and Achilles tendon can also operate like springs, using what is known as the stretch shortening cycle (SSC) and stretch reflex phenomenon. (This is also known as elastic recoil). When the mid to forefoot lands under the body, the Achilles tendon and calf muscle become fully stretched (like a stretched elastic band). As the foot leaves the ground, these become fully contracted and just as in elastic band the potential energy is released resulting in a much more efficient movement.
But, unlike our elastic band, our elastic tissues do not always ‘ping back’. If we stretch a tendon for example , for too long – it will lengthen and the potential energy will be lost. If our landing foot spends too much time loading the stretch on the ground, maybe because we have made ground contact in front of our body, then we cannot make use of elastic recoil – the opportunity is lost.
In order to maximise the opportunity of using elastic recoil and the SSC to make us super efficient runners we need to minimise our ground contact time. Getting your body position right to enable you to contact the ground in the right way is central to minimising ground contact time.
You can read more about getting your body position right here.