Analysing the one-leg jump, part IV: The importance of the hamstrings

Now I want to continue our journey through the kinetic chain and talk a bit about the hamstrings. We have discussed about the amortization phase and the possible disguise of quad strength (or weakness) and quad dominance, and its effects in the amortization phase.

But now I want to turn our attention to the hamstrings, which is an interesting muscle group that has a bunch of roles and some unique characteristics.

First off, we have to understand that the hamstrings are a biarticulate group of muscles. This means that they cross two joints – in this case – the knee and the hip joint. For this reason, they have two important properties that muscles that are uniarticulate don’t have: the property to get into active insufficiency and the property to get into passive insufficiency. So what the heck does that mean?

Well, let me quote

Active insufficiency is the inability for a biarticulate muscle to exert enough tension to shorten sufficiently to complete full range of motion in both joints simultaneously.

Passive insufficiency is the inability for a biarticulate muscle to stretch enough to complete full range of motion in both joints simultaneously.

More information here:

The same applies, by the way, to the calves. They’re also biarticulate muscles.

Well, OK, we now know that they have these properties and that they’re biarticulate, but what does that mean in practical terms? It means they perform functions that address either flexion or extension of the joints that they control. In the case of the hamstrings, they flex the knee at one end and assist in extending the hips at the other end. Why “assist”? Because the primary role of hip extension should be the role of the glutes. Assuming you don’t have glute amnesia, shut down glutes, tight hip flexors, or what have you, then the glutes should be doing the hip extension/hip hyperextension with the hamstrings assisting the glutes.

For the calves (about which we will discuss extensively in a later article) – they also perform knee flexion and they perform foot plantar flexion (basically, calf raises, or ankle extension).

Now knowing these two properties of biarticulate muscles possibly ending up in active or passive insufficiency, we can then address how the proper stretching of these muscles should be performed (putting them into passive insufficiency), and how the proper training should be performed (avoiding active insufficiency). That’s why you stretch your hamstrings by keeping your knees straight and bending forward and down – you keep them stretched at the knee end and then you stretch them further at the hip end – putting them into passive insufficiency. That’s also why you want to do Romanian deadlifts targeting the hamstrings without allowing the knees to travel forward – if you allow the knees to travel forward, you’re allowing the hamstrings to be shortened at the knee while you’re stretching them at the hip (lowering the bar) – so basically their length really doesn’t change all that much resulting in very poor training results.

This knowledge helps us understand further what is going on in the amortization phase in a one-leg jump. Let’s get back to our good ol’ failed jump example:

Raptor knee collapse picture
This is how knee collapse looks like

We have talked about a few reasons of why you can end up in the position that I’m in this picture. But there’s yet ANOTHER reason for this possible knee collapse, and it has to do with the hamstrings this time. And at this point, there are actually several reasons why the hamstrings could be the culprit:

  1. Strength – If you plant correctly for a one leg jump, like the guy in the image below
    Amortization phase picture
    Good one-leg jump plant

    but you don’t have the necessary hamstring strength, the CNS will feel this lack of strength and will try to relieve the hamstring from a potentially dangerous load/stretch. To do this, the body (CNS) will de-activate the hamstring (shutting down its neural firing) and allow the knee to travel forward, with the quad then taking the responsibility of decelerating the tibia from traveling forward (thus, the quad is given this big responsibility of stopping the tibia and avoiding knee injury). Then, if you’re lucky, once the hamstring dangerous stretch has been avoided, both the quad and the hamstring of the jumping leg will work together to just prevent injury by stopping the tibia from traveling further forward (like in the case of my failed jump) and completely shutting down in terms of providing power for an actual jump.

    How to cure this? Get stronger hamstrings and get the ratio between quad and hamstring strength closer. You don’t want to have beast quads and very weak hamstrings. Ever. As a one leg jumper, you should be very comfortable doing sets of 6-8 reps of natural glute-ham raises without assistance in order to call yourself strong in terms of hamstring strength. You should also be pretty good in doing Romanian deadlifts while being in anterior pelvic tilt during the lowering part of the lift, in order to get to the hamstrings more. Normally you’d want a neutral spine all the time, but staying in a bit of anterior pelvic tilt will recruit more hamstring and use less glute. I would still try to get towards a posterior pelvic tilt at the top of the lift to get the final glute contribution, but you have to be under control at all times and know what you’re doing.

  2. Shut down glutes – In this scenario, the hamstrings are overactive. It’s either because the glutes are underdeveloped with the hamstrings overpowering them or because the glutes are shut down altogether. So the approach is the right one (trying to hip extend to jump off one leg) – but it’s done with the wrong tools – the body is trying to use the hamstrings entirely. It will look like this:
    Overactive hamstrings picture
    A sign of shut down glutes – trying to use the hamstrings while bending forward at the hips to stretch them and “wind them up”

    What is going to happen is you’re going to bend forward at the hips in order to stretch the hamstrings, and your last stride before jumping will be very long. You’re going to feel that urge because you have to find a way to hip extend, and if the glutes are shut down, then the hamstrings are the only ones who can do it. So you’re going to bend forward at the hips to stretch the hamstrings (while not bending at the knee) – in order to load them up to jump. This moves the center of gravity forward and will also create a breaking effect – loading up the knee and transforming the jump into more of a long jump rather than a high jump. If the chest is oriented downwards, the tendency will be to jump forward. Sure, SOME glute contribution might still happen at the end of the movement, but this is not a optimal way to jump. You’re not going to fully engage the glutes, you will overload the knee, you’re going to receive a breaking effect diminishing your speed by taking a very long last step and you will spend MORE time on the ground in the amortization phase in order to load up the hamstrings by stretching them – thus being more on the muscular side of things and less on the tendon side of things (more about this in a future article that will be of extreme importance after we understand the muscular contributions to the one leg jump). This translates into decreased performance and possible overuse injuries because of the excessive knee load.

    How to cure this? Improve glute strength and improve glute activation. KB swings done with a neutral spine and finishing the reps into posterior pelvic tilt, hip thrusts with posterior pelvic tilt at the end, improving core function with planks and increasing general core strength are your keys to this puzzle. Also, calf work might help too. because calf work usually helps with the entire kinetic chain when something is wrong with it (for reasons we will talk about in a future article). In terms of plyometric work, some additional emphasis on short step submaximal jumps like the pen drill (where you jump and land and jump in succession using short steps) might be a good idea.

  3. Inflexible hamstrings – the lack of hamstring flexibility could be an important part of a collapsed knee in a one-leg jump. To solve this, work on your flexibility more, do drills for dynamic hamstring flexibility each time you warm up, and do static stretching work for your hamstrings each time you cool down, after a game etc. Go crazy. Use dynamic, static and PNF stretching if you have a partner to help you, or by using a towel. Wrap a band or a towel around your foot, sit on your back on the ground, let one leg rest on the ground and get the other leg vertical, keeping the knee straight, while pulling on the band towards you. Pull towards your chest on the band/towel for 5 seconds and then relax for 5 seconds. Repeat for 1-2 minutes.

Ultimately, as one leg jumpers, we want to have beast hamstrings. They help a ton in the more straight-leg oriented plant that we use (vs the two-leg jumpers) and they help, in a perfect world, the glutes to do the hip extension. The thing you have to keep in mind is that if you want to be a one leg jumper you will NEVER be a good one with weak hamstrings. The same with sprinting – you won’t ever be a great sprinter with weak hamstrings. They are THAT important when the knee isn’t bent. They also possibly have the highest percentage of fast twich muscle fibers in the body vs any other muscle – so they act very well at high speeds, therefore they are very important in the one leg jump, which has a very low ground contact time and a very short amortization phase. Because of this, they allow you to use your tendons more and your muscles less, for which reason they are once again paramount in their importance in the one leg jump.

And because they are fast twitch by nature, make sure you train them for performance using sets of no more than 8 reps, no matter the exercise – glute ham raises, Romanian deadlifts, leg curls, doesn’t matter. Please remember – become a beast at your hamstring strength and NEVER ignore them if you want to be a great one leg jumper.

In the next article I will talk a bit about the calves and the foot, and their relationships with what they determine to happen in the rest of the kinetic chain, and then we will discuss the tendons and some very less known facts about them and their (huge) importance.

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