How PNF Increases Performance
Transcribed from video:
Not only do you get an increase in the muscle length, but also it’s ability to generate force. And we’re going to talk now with the benefits of PNF. Why that is the case, one of the reasons that is the case when we get down to this fourth point here.
Let’s start off with the first benefit of PNF, and we’ll talk exactly about how to do PNF as we go. There are reduced injury rates. There’s less stress on the musculoskeletal system. If we go back to our ship mast model where we say here is your boat, here’s the mast. If these two things are super tight, eventually you’re going to get some sort of degradation, or deconditioning, or damage to the mast of the ship and eventually it’s going to probably shoot straight through the bottom and the whole thing’s going to sink. Because they’re too tight. It’s putting too much stress and strain on a joint, which we don’t want. Because too much pressure and strain on a joint is going to wear some of those softer structures inside that joint. So if we can be in better positions and have less tension on our joints, our injury rates are going to start to drop. It also creates better force generating positions.
So let’s again look at two examples of a squat. We’ll look at a squat which is more inclined forward, like this. We’ll look at this angle here a bit also. And then we look at a squat which is more upright, as a squat should be. Let’s call this a front squat. You’ve all seen people who do front squat like this with the weight forward, with the bar forward. The load is here. Now when this person stands up the load has to get back to up here as they stand up, you see that? So the load has to be lifted this distance but it also has to be moved back this horizontal distance. So it’s got a long way for the load to travel. In this example the load is here, it’s going to end up here. Doesn’t have to travel as far. Every single ounce of energy, every newton of force in this picture for this squatter, is going to go into getting the bar against gravity and that’s where we need to go. That’s what all this stuff is about. We’re trying to move a load against gravity. Whereas here this individual has to not only lift it the same distance to get the bar from down here to up there, but they have to pull it back into position and fight to overcome the gravity that’s pulling down on their body at the same time. So if we can get into good positions, every little bit of energy and force you create is going to go into the bar and your lifts are going to go up. Okay? So that’s why this allows it to get into better force generating positions.
Of course there are less poor positions up and down the chain as we saw. If you have issues in flexibility through your ankles then the ankle is tight. The knee gets pulled back is one of the things you’ll notice here is how much angle we’ve got at the ankle. Whereas here there’s a lot more angle there. This is tight, the knee is pushed back, the hip is pushed back. Every action has an equal or opposite reaction to maintain balance. This has to come forward. So we get these compensatory effects up and down the chain. Okay? This is the fun bit though. The increased range of force production. There’s a relationship our muscles have between how long they are and how strong they are.
Let me give you an example. Alright, that lid is as tight as I can get it. Stand up for me Danny. Hold that, turn around and I want you to get ready to try and open that. I’m going to give you one shot, you’ve only got one second to try and open it. Not yet, don’t loosen it yet. Okay, ready, get into position but don’t start until I say. In position ready, ready. Notice the position of her body, look at the angle of her elbows. We ready? And open it. Okay, got it. Thank you. What did you notice about the position of her elbows as she started to open that bottle? What was the angle? They were at about 90 degrees. She inherently just went into that position cause it’s strongest. If someone said that to you… I once did this with a jar of Nutella when there’s actually an incentive for someone to get into there. You wouldn’t do this, would you? You wouldn’t try and open it like this, cause you just naturally and inherently know that this is the position that’s going to be stronger. But have you ever thought why that would be the case? You’re opening a jar, it’s always here, isn’t it? You’re never opening it out there, because our muscles are strongest at their midpoint. And we can actually graph that, and this is what it looks like. If this is the strength or the length rather of our muscles… That’s how long our muscles are. And this is the strength, or our ability to generate force. We get this shape that looks like that.
It’s called a length tension curve, and it talks about how able we are to produce force at different ranges of motion of our joint. So for example, using that same example here. Doing a bicep curl here, my bicep is weak at this point. If I come up all the way to the top, my bicep is weak. But if I’m there in the middle, that’s where it’s at it’s strongest. Who really suffers from poor overhead mobility?
Alright, jump up Daryl. Let’s have a look at the differences in the ability to generate force at different ranges. Show me your overhead position. So face me, good. Lift the arms up all the way back. Feel tight there? Working hard to try and maintain position. Hold that position. Just go forward like a centimetre with your arms, that’s it. Keep all this strong, and now push back against me as hard as you can. There’s not much power there. Okay, now go down to 90 degrees, here. Now push up against me, and now I’m having a work, okay? Have a seat, cool. So you can see it’s the same muscles trying to do the same movement, that being flexion of the shoulder. But he’s super strong here and I could hold him back with this single finger over here. And can you see how it doesn’t matter how much he can bench press. That has no bearing on how much he can strict press, how much he can get over here. Because what’s happening is his muscles here are in their mid-range. This narrow band here, where you’re able to maximise how much force you can produce. His muscles are not in a shortened position back here. Then on the lengthened position up here, they’re somewhere in the middle. This sort of Goldilocks, just right effect. What’s happening is if he was back here and trying to push forward or he was up here and trying to pull back… At the extremes of range can you see how there’s not much strength being produced? There’s not much strength being produced.
Let me simplify this for you. If your muscles and joints are tight, you cannot produce maximum force at that range. So flexibility is not just for the sake of flexibility and more movement through your joints, it actually makes you stronger as well. So what do we have to do to this curve to be able to generate more strength? How does that change this? You have to make it fatter, wider, yeah? If we do this… Like that. These same extremes of range are now up here, look how much more strength you’re getting. See that? And this is what PNF does. It takes this length strength curve and it fattens it out. Is this new athlete, post PNF work… Is that new athlete any stronger in terms of peak strength than the athlete was previously?
If you put them in a lab and said contract your muscles as hard as you can and we’re going to graph every little thing and see how much force you can generate… Is there any difference? In clinical lab based setting, there is no change. If you ask this new athlete to retest their strict press, are you going to see a difference? Who says yes? Who says no? The peak strength is the same, but in an athlete like Daryl… Is he limited here by his ability to squeeze his muscles really hard or is he limited by his ability to have the flexibility to get there? It’s the flexibility. So even though his peak strength does not increasing, his lab based clinical white lab coat wearing strength is not increasing, his ability to use that strength… To actually do something useful that we actually care about is increasing. Because now he’s no longer at the end of range here where he can’t… He can now do this and come well further back which means that now he’s back in the middle and he’s back generating a lot of power and a lot of strength.
So this is why improving your flexibility through PNF, through proprioceptive neuromuscular facilitation, allows you to become stronger. Cause flexibility isn’t really sexy. It’s not often that you have someone come up to you and say, “Oh hey, how much do you stretch?” It’s going to be how much do you lift, that’s what matters. And in the end we do flexibility to make us better at something else. It’s a means to an end. We do strength work to get stronger, but we can do flexibility work also to get stronger.
We’re not just stretching for range, we’re stretching for usefulness. And that’s the thing with PNF, I like to think of it as a functional flexibility. One that we can actually use. Not someone who just does a lot of yoga who doesn’t have the stability to go along with it. So this is where we have an overlap between being strong, being stable, and being mobile at the same time. Can everyone see how by doing this PNF, which I’m about to talk you through, how doing this PNF is going to increase our ability to generate force? Which is a good thing.
Dan Williams is the Director of Range of Motion. He has a Bachelor of Science (Exercise and Health Science) and a Postgraduate Bachelor of Exercise Rehabilitation Science from The University of Western Australia, with minors in Biomechanics and Sport Psychology. He has worked with many thousands of individuals along the full spectrum of health, and has coached at The CrossFit Games. He regularly presents to corporate and fitness industry groups and mentors Fitness Professionals.