T Nation

Posterior chain?


#1

Hi all, from what i read (and try of course) p-chain work is excellent for atheletic performance. I do find that my athletes and myself are quicker and more explosive from a "defensive stance" kind of position. In addtion WSB style stuff has be adding 30lb to my bench after a year of stagnating:) However i do have a question, it is about the vertical leap. I Defranco says the correct technique is to go down only to a quarter squat position befor jumping. Hoever isnt this a QUAD dominant position? so is the P-chain less important (in comparision, im sure its still important) that in other movements? eg. sprinting, defensive slide etc...
I also asked this question in the EFTS forum.. :slightly_smiling: would like to hear what ppl think.

regds
Jonathan


#2

I think with the quarter squat he meant a quarter squat breaking the hips, so no knee movement at all. If you look at the jumping movement, you see a person with butt out, and the knees bent very little, so yeah, I think the posterior chain is more involved. I also think this subject has no real answer, as everybody jumps different.


#3

You are forgetting that the rear chain is recruited by pushing the butt out, and by an exagerated forward lean when you go down.

If you were to try to maintain an erect back, like when squatting the gather would be stronger quad emphasis, and if you really stayed upright, as in a B-builder squat, it would be very quad dominant.

My wife is a quad dork as a jumper. She was trained in ballet (upright and graceful...little gather), and then trained as a middle in V-Ball..slight dip, arms up near ears, little forward lean due to relation to net. So, she is very quad dominant and a quick jumper.

Luckily the vert test allows a huge armswing, a big upper body coil, thus breaking the hips and recruiting the rear chain, and a slight 15-45 degree knee bend...

Does this make sense?

The quads are more involved in the vertical than many give credit for, but the best jumpers recruit the rear chain dominantly, and use both quads and rear chain to derive power.

Lil' Coach H
CSCS


#4

There are a few studies done on this and fortunately I was able to dig out a couple :). Feel free to read through the abstracts below but I'll summarize the info. here.

The 1st one shows muscle contribution broken down by the following muscle groups and their % of contribution:

23% ankle extensors
28% hip extensors
49% knee extensors

The 2nd one looks at 2 different types of jumps, the vertical jump and the broad jump. They found the following differences.

broad jump
45.9% hip extensors
3.9% knee extensors
50.2% ankle extensors

vertical jump
40 % hip extensors
24.2% knee extensors
35.8% ankle extensors

Obviously there are differences between the 2 studies but the information does seem to verify that the more forward lean and the more the hips are pushed back (broad jump vs vertical jump), the more the posterior chain and less the quadriceps are involved.

A work-energy approach to determine individual joint contributions to vertical jump performance.

Hubley CL, Wells RP.

A work-energy approach was used to determine the contributions of the muscles crossing the hip, knee and ankle joints to the total positive work done during maximal vertical jumps. It was found that the average relative contributions of the ankle and hip muscles were approximately 23 and 28% respectively, with the remaining 49% of the work being done by the muscles acting at the knee joint. The efficiency of jumping, i.e. the ratio of potential energy gained to the net mechanical work done by the muscles acting at the three lower limb joints was nearly 1.0. These results stress the importance of all three major leg extensor muscle groups to the performance of an explosive activity such as vertical jumping. It is suggested that the work-energy approach supplies useful information concerning joint contributions without the problems associated with other techniques.

Kinetics of standing broad and vertical jumping.

Robertson DG, Fleming D.

The purpose of this study was to determine the contributions made by the leg muscle groups to the external mechanical work done in standing broad and vertical jumping. Six subjects were filmed jumping from a force platform. Linked-segment analysis and inverse dynamics methods were used to compute the muscle moments of force and power and work output created by these moments of force. Results support the principle that all three extensor moments of force summate in both types of jumping but that the sequence of contractions was not from proximal muscles to distal as is stated by the continuity principle. Instead all three extensor moments act simultaneously to produce leg extension. The contributions made by the three muscle groups were not the same for the two types of jumps. For the propulsive phase of the standing broad jump the contributions of the hip, knee, and ankle muscles were 45.9%, 3.9%, and 50.2%, respectively, whereas, for the vertical jump the contributions were 40.0%, 24.2%, and 35.8%, respectively. These results indicate that broad jumping utilizes the muscle groups differently than vertical jumping and show the importance of the hip and ankle musculature in the production of external work in jumping.


#5

CaptnJ,

Got home from the gym early today and decided to check out the forums for the first time! I saw that you mentioned my vertical jump recommendations so I wanted to stick my 2 cents in.

Anyway, Silverback seems to be on the money regarding your question.
CaptnJ, remember that the angle of knee flexion only tells part of the story. The angle of your trunk tells the other part of the story. (Think about performing a good morning. Your knees are only flexed a couple of degrees, but this exercise isn't a quad-dominant exercise.)
Although everyone has an individual jumping style, my best athletes flex about 15-25 degrees at the knee and 30-40 degrees at the trunk. Flexing at the trunk helps to recruit the spinal erectors to a greater degree. Strong erector muscles help you to "jacknife" out of the bottom position.

Now, this doesn't mean that I want you to go crazy thinking about specific joint angles when you jump. They are just used as guidelines.

One more note: I've done extensive research and video analysis on over 2 dozen athletes who jump 35+ inches. The #1 determining factor in their jump heights WASN'T knee or hip angles. The #1 factor was the speed at which they descended into their jumps. The bottom line is THE ATHLETES WHO DESCENDED THE FASTEST ENDED UP JUMPING THE HIGHEST!

Hope this helps.
Joe D.


#6

For a basketball player, however, you want to make sure that you don't become a "back" jumper. This is where you have the forward flexion of the trunk. Back jumpers are slower than jumpers who initiate the leap from the knees and keep the torso erect. This was pointed out to me by Al Vermeil, strength coach for the Chicago Bulls. That is why is recommended for athletes to stick to Olympic style ass to the grass squats since it will carry over. Watch an NBA game sometime and you will notice the best leapers do not bend at the truck when going for a rebound. It is not necessarily how high you jump but how fast you can reach that height, bending at the waist will slow you down significantly.

Trench


#7

Wow what wonderful replies, thanks everyone. And joe, i ordered you video from EFS... cant wait to watch it!

regds
jonathan


#8

CaptnJ,

You will really like Joe's video...it is very well done, and the information is right on... one of the better videos I own in terms of straight forward, no-nonsense, immediate result producing information. Plus, it is actually very high quality compared to many videos out there.

Lil' H