The Length-tension relationship
Length-tension relationship refers to the overlapping of microfilaments in a sarcomere. Heads of the myosin proteins need to grab the binding. The Length-tension Relationship. For muscles to contract, the muscle proteins called actin and myosin must interact with each other. This occurs when they are . In this video, learn about concentric/eccentric/isometric contraction and the length -tension relationship of muscle. Understand the passive.
And that was talking about how if you stretch out heart cells, and all of the things within heart cells-- all the proteins-- that it actually changes the force of contraction. And actually, force of contraction is very much related to this length-tension relationship as well. So I'm going to put that up here.Sarcomere length-tension relationship - Circulatory system physiology - NCLEX-RN - Khan Academy
And instead of using that terminology, though, we're going to use the term tension. I mean, you can essentially think of them the same way. But classically, the word tension is what everyone uses. So we're going to use that same word. And then, as far as length, specifically the length that we're talking about is the length of a sarcomere. So I'm going to write sarcomere here. And the sarcomere, just keep in mind, is really going from one z-disc to another z-disc.
So to draw this out, to actually write it out maybe, we can start with myosin. And so maybe this is our myosin, right here.
And I'll draw some myosin heads here. And maybe some myosin heads on this side, as well. And, of course, you know it's going to be symmetric looking, roughly symmetric. So this is our myosin. And actually, I'm going to make some copies of it now, just to make sure that I don't have to keep drawing it out for you. But something like that.
And we'll move it to be just below so that you can actually see, when I draw a few of them, how they differ from one another. So I'm going to put them, as best I can, right below one another. And we'll do a total of, let's say, five. And I think, by the time we get to the fifth one, you'll get an idea of what this overall graph will look like. So these are our five myosins. And to start out at the top, I'm going to show a very crowded situation.
So this will be what happens when really nothing is spread out. It's very, very crowded. And you recall that you have actin, this box, or this half box that I'm drawing, is our actin. And then you have two of them, right? And they have their own polarity, we said. And they kind of go like that. And so, in this first scenario, this very, very first one that I'm drawing, this is our scenario one. We have a lot of crowding issues. That's kind of the major issue, right?
Because you can see that our titin, which is in green, is really not allowing any space. Or there is no space, really. And so, these ends, remember these are our z-discs right here.
This is Z and this is Z over here. Our z-discs are right up against our myosin. In fact, there's almost no space in here. This is all crowded on both sides. There's no space for the myosins to actually pull the z-disc any closer. So because there's no space for them to work, they really can't work. And really, if you give them ATP and say, go to work. They're going to turn around and say, well, we've got no work to do, because the z-disc is already here.
So in terms of force of contraction for this scenario one, I would say, you're going to get almost no contraction. So when the length is very low, so let's say this is low. Maybe low is not a good word for length. Let's say this is, I'll use the word short. The sarcomere is short. And here the sarcomere is long. So when it's short, meaning this distance is actually very short, then we would say the amount of tension is going to be actually zero. Because you really can't get any tension started unless you have a little bit of space between the z-disc and the myosin.
So now in scenario two, let's say this is scenario two. And this is my one circle over here.
In scenario two, what happens? Well, here you have a little bit more space, right? So let's draw that. Let's draw a little bit more space. Let's say you've got something like that. And I'm going to draw the other actin on this side, kind of equally long, of course. I didn't draw that correctly. Because if it's sliding out, you're going to have an extra bit of actin, right?
And it comes up and over like that. So this is kind of what the actin would look like. And, of course, I want to make sure I draw my titin.
Sarcomere length-tension relationship
Titin is kind of helpful, because it helps demonstrate that there's now a little bit of space there where there wasn't any before. And so now there is some space between the z-disc and this myosin right here.
So there is some space between these myosins and the z-discs. In fact, I can draw arrows all the way around. And so there is a little bit of work to be done. But I still wouldn't say that it's maximal force. Because look, you still have some overlap issues. Shift of optimum angle after concentric-only exercise performed at long vs.
Sport Sciences for Health, 12 1 Behavior of fascicles and the myotendinous junction of human medial gastrocnemius following eccentric strength training. Inter-individual variability in the adaptation of human muscle specific tension to progressive resistance training. European journal of applied physiology, 6 The variation in isometric tension with sarcomere length in vertebrate muscle fibres.
The Journal of physiology, 1 European journal of applied physiology, 99 4 Effect of hip flexion angle on hamstring optimum length after a single set of concentric contractions. Journal of sports sciences, 31 14 Short Muscle Length Eccentric Training. Frontiers in Physiology, 7. Neuromuscular adaptations to isoload versus isokinetic eccentric resistance training.
Training-induced changes in muscle architecture and specific tension. European journal of applied physiology and occupational physiology, 72 Investigation of supraspinatus muscle architecture following concentric and eccentric training. Journal of Science and Medicine in Sport. Impact of range of motion during ecologically valid resistance training protocols on muscle size, subcutaneous fat, and strength.
Sarcomere length-tension relationship (video) | Khan Academy
Eccentric torque-producing capacity is influenced by muscle length in older healthy adults. The effects of repeated active stretches on tension generation and myoplasmic calcium in frog single muscle fibres. The Journal of Physiology, Pt 3 Changes in muscle architecture and performance during a competitive season in female softball players.
Effects of isometric quadriceps strength training at different muscle lengths on dynamic torque production. Journal of sports sciences, 33 18 Changes in the angle-force curve of human elbow flexors following eccentric and isometric exercise. European journal of applied physiology, 93 Effects of eccentric strength training on biceps femoris muscle architecture and knee joint range of movement.
European Journal of Applied Physiology, 6 Effects of eccentrically biased versus conventional weight training in older adults.
Effect of resistance training on skeletal muscle-specific force in elderly humans. Journal of Applied Physiology, 96 3 Differential adaptations to eccentric versus conventional resistance training in older humans.
Experimental physiology, 94 7 Muscle architecture and strength: Early skeletal muscle hypertrophy and architectural changes in response to high-intensity resistance training.
Journal of Applied Physiology, 1 Quantitative analysis of sarcomere non-uniformities in active muscle following a stretch. Contraction type influences the human ability to use the available torque capacity of skeletal muscle during explosive efforts. Proceedings of the Royal Society B: Biological Sciences, Damage to human muscle from eccentric exercise after training with concentric exercise.
The Journal of Physiology, Pt 2 Effects of repeated eccentric contractions on structure and mechanical properties of toad sartorius muscle. Shift of peak torque angle after eccentric exercise. International journal of sports medicine, 29 3 ,