Posterior Chain versus Anterior Chain: Which is More Important?

Written by Jack Woodrup for VerticalJumping.com

In vertical jump training the posterior chain receives a lot of recognition, but does it really trump the level of importance the anterior chain plays? This very question was recently asked over the Vertical Summit, and we will attempt to answer it here: Who is the master of the vertical jump?.

It is a very good question. After all we all want to jump as high as possible in as little time as possible and wasting months of training on a muscle group that doesn't add much in terms of jumping improvement is not something anybody wants to do.

As it is a topic that vertical jump athletes discuss frequently we thought it was about time for some Vertical Jump Hompeage analysis.

The Posterior Chain: What Is It and Why Is It Important

Figure 1: The muscles of the posterior chain.

The posterior chain is the group of muscles that runs from your lower back down behind your legs, hence the name, posterior. These muscles include the lower back, the glutes, the hamstrings, and also the calves.

These muscles are important in vertical jumping because they are larger they also produce a lot of power, particularly the glutes and hamstrings. In fact the glutes have one of the higher ratios of fast twitch fibers of any muscle group in the whole body.

In terms of the actual jumping motion itself the posterior chain is involved as follows. As you bend your knees and descend down into the eccentric phase, the hamstrings contract. The more powerful your hamstrings are, the more forcefully you will drop down. The quicker you can get down, the higher you will jump.

On the concentric or upward part of the jump, your glutes, lower back and calves produce powerful contractions to extend the hips, knees and calves (the triple extension) and throw your body skywards. Once again, the more power in these muscles translates into a more powerful triple extension, which in turns translates into a higher vertical jump.

Anterior Chain: What Is It and Why Is It Important

The muscles that comprise the anterior chain are often referred to as the beach muscles. These include the chest, abs, and quads. For the purposes of vertical jump training though we can probably not worry too much about the chest.

The anterior chains role in vertical jumping is as you would imagine, the opposite of the posterior chain. As you descend into the negative portion of a jump the quads lengthen in an antagonistic fashion to the hamstrings. Then after the lengthening they are required to reverse that downward motion and powerfully contract back again to extend the knees and hips and drive your jump high.

The abs contribute by contracting in the downwards portion of the jump and lengthening in the upwards phase. If you have powerful abs they will assist you in improving the negative or downards part of the jump.

So Which Is More Important - Posterior or Anterior?

Without getting all philosophical here I think Newton summed up this debate best when he said "for every action there is an equal and opposite reaction". He may have been talking about our two muscle chains.

He may have also been talking about the myotatic reflex which is one of the most important and beneficial central nervous system events that occurs in a vertical jump. The myotatic reflex is an instinctive protective action your body takes when you lengthen a muscle fast and powerfully.

In a vertical jump it comes into play when you throw yourself downwards into the jump. Powerful hamstrings are able to pull your quads into a stretch position very quickly. Here the reflex kicks in and your body reacts by instinctively reversing against the sudden stretch.

The effect of this is that your body contrcts the quadriceps casuing knee extension (straightening of the legs) which rapidly switches your movement direction from downward back upwards. Of course the myotatic reflex doesn't provides all of your jump height. But it helps.

This is demonstrated by the fact that most people will have a higher vertical when they jump of a small box than from just doing a pure counter movement or standing vertical jump test.

The effect that jumping from a box has is that it increases the downwards force (in essence aiding the hamstring contraction by giving them a gravity based thrust), and thus increases the reversing power of the myostatic response. The result, you jump higher. Increasing hamstring strength has the same effect for when a box isn't available to jump for example, when you are actually playing your sport.

But a vertical jump doesn't end there. You still need to be able to follow through from the involunatry myotatic reflex with a powerful voluntary contraction in your quads, glutes, and calves in order to maximize the power in your triple extension and therefore your jump height.

So this is one reason why the anterior chain and posterior chain are equally important. There is also another very good reason to treat them as equals. You see the body is a very smart thing. It has various survival instincts that you cannot control. For example, you cannot consciously stop your heart beating.

Another one of these survival instincts is that your body will try and not allow your muscles to contract in such a way that you are going to injure yourself. It does this by inhibiting how powerfully you can contract a muscle if it knows that the antagonistic (opposing) muscle isn't strong enough to stabilize the movement against the agonist (contracting) muscle.

In other words, if your hamstrings are weak and your quads are strong, you will not be able to fully apply the power in your quads as you jump upwards. If your hamstrings are strong, but your quads are weak, you will not be able to descend as powerfully as you want into your jump which will limit your ability to generate a decent myostatic response.

So is one more important than the other? No. Strong and powerful hamstrings are the major muscles that drive the negative part of the jump and initiate the myotatic reflex. The more powerful they are the more powerful the reflex will be and the more upwards thrust will be generated. Strong and powerful quads, glutes, and calves then provide the rest of the power to finish of your jump.

A nice analogy of the situation would be that of a fighter plane on an aircraft carrier. An jet takes off from an aircraft carrier by being hurled off the deck by a slingshot (the myotatic reflex generating hamstrings), but it also requires powerful jets (quads, glutes, and calves) to continue the motion so that it doesn't just fall off the edge and land in the sea. You can't have one without the other. The powerful jets take a little bit of time to get going so the slingshot gives them the extra thrust they need.

Figure 2: The Trap Bar Deadlift. The trap bar deadlift is a great strength building exercise for both the posterior and anterior chain and hence it is also a tremendous exercise for increasing your vertical jump. Just be careful though, it may make you wear bad lycra shorts.

But What About All The Posterior Chain Hype I Have Been Hearing

Yes the posterior chain has been getting a lot of attention, and yes it plays a vital role in not only vertical jump, but most athletic performance. These two things are undeniable. What is also undeniable is that the role of the posterior chain is no more important than that of the anterior chain.

The reason it has gotten so much press lately is due to the simple fact that many athletes are massively under developed in the posterior chain. This is most probably a side effect of too much emphasis on bodybuilding type training methods (train what looks good), and not enough on performance training (what actually works).

Lately the pendulum has swung back the other way, possibly too far and now many athletes are getting too focused on the posterior chain and ignoring, to their detriment, the anterior chain. The bottom line is you have to train both if you want to maximize your vertical jump.

Conclusion

We know it is a bit an anti-climax of an answer to suggest that they are both equally important, but it is true. They ARE both important. Imbalances in the strength and power between the muscles of the two chains not only reduces performance (i.e jump height), but is also one of the quickest ways to injure yourself. If you have a deficiency in one area, whether it be your anterior muscles or your posterior muscles, the first thing you should focus on is rectifying that deficiency.

It is mentioned on our site a number of times that identifying and ironing out your weaknesses, followed by a balanced approach will ultimately yield faster, and more sustainable improvements. This article almost certainly won't end the debate for some people, but we hope it gives you some good food for thought.