Understanding Active Stiffness and other elements that make a perfect landing
Jumping and landing are integral movements in most sports. Without landing perfectly, it is hard to prepare for the next maneuver. So, what makes for a perfect landing? And how do you land safely without jeopardizing your body with injuries? This is the science behind the perfect landing!
For us to understand what constitutes a perfect landing, we must first understand active stiffness.
Stiffness refers to the mechanical resistance to elongation or shortening of the muscle, tendon, joint and connective tissue. This stiffness can be measured with the muscle in a passive or active state. This active state is talking about the contractile elements (sarcomeres) contributing to the stiffness of the muscles. Depending on the level of muscle activation, different components of the muscle will provide greater resistance to stretch, a.k.a. active stiffness.
For a good example of how increasing muscle activation can improve active stiffness in landing and reduce ground contact time, refer to our video on Instagram called “How to improve your landing technique”.
Now that we know what active stiffness is, let’s look at the biomechanical equation in the context of landing and its importance.
Active stiffness: contractile resistance to stretch
Peak force: the amount of force exerted during a movement
Displacement: change in position of an object from position A to B with a specific direction and magnitude.
The less active stiffness we have (reduced muscle activation / strength), the more displacement occurs during landing. As the displacement has increased, we spend more time in contact with the ground. In the sports setting, it is ideal to reduce ground contact time and spend more time preparing for the next maneuver such as pushing off or going for a jump.
Sounds confusing? Let’s look at an example.
During a drop jump from a plyometric box, displacement starts to occur from the initial contact of the toes against the ground. At this point in time, your ankle joint, achilles tendon and calf muscles absorb the impact; and depending on how high your active stiffness is, it determines how far your heel will travel or displace. Thus, high active stiffness (greater resistance to stretch) will reduce your displacement from point A to B. This also means your peak force produced during contact will be high (this is measured by VALD Forcedecks / Force plates) and there is less ground contact time.
After learning and understanding the basic physics behind landing, what other factors constitute a good landing?
Perfect Landing
A perfect landing consists of:
high active stiffness
strong muscle stabilisers to keep joints in neutral position during landing
good reaction time and activation of muscle groups to counter external and internal perturbation and keep the centre of mass within the base of support (balance).
High active stiffness
During landing, stiff achilles tendon might be advantageous due to quick force transmission from the muscle to the bone. Although active stiffness is not the key determinant in jumping performance, it definitely reduces the ground contact time.
Improve active stiffness through increasing muscle strength and activation by specific programs such as isometric, plyometric or eccentric training with high magnitude protocols with low frequency.
Strong Stabilisers
The aim of muscle stabilisers is to keep your body in its intended position during an activity, especially if there is an external perturbation during landing i.e. going for a layup in basketball there may be physical contact with another player during landing. Therefore, strengthening your core stability, shoulders, and hips are very important as this will allow you to stick to your position for a safe landing.
Reactive / dynamic balance
If we don’t have good reactive balance, just having high active stiffness, joint mobility and strong stabilisers are not enough for a perfect landing. Reactive balance is how quickly your body reacts to external perturbation or stimulus and carries out the appropriate response in order to keep your center of mass within the base of support. In the sports context, this becomes extremely important as this can likely prevent serious injuries.
How injuries affect your landing
Injuries can be detrimental to your sporting performance and especially your landing technique. This is because injuries usually affect most if not all the components mentioned earlier. This means you may experience pain-related muscle inhibition, acute swelling and decreased joint mobility. Even after acute symptoms have settled down, your muscle activation, strength, mobility and balance may not return to normal level. This makes returning to play prematurely quite dangerous as the risk of re-injury is high. Therefore, it is important to still go through proper rehabilitation and get a proper assessment by your physio to see if you are ready for return to play.
Interested in improving your landing or jumping in your chosen sport? Talk to us today!
This blog is written by our physiotherapist Eric Chao.
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