A Theory of Body Tension: Tying the Concepts Together (Finally!)

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After describing the forces at work on hand and footholds as well as the function of kinetic chains we can now see how these features are at work in body tension.

You will remember that the contact force and the friction force are proportional, as the contact force increases so does the friction force. In situations where the angle of the hold surface is not perpendicular to the line of force our hand or foot applies to it, the friction force plays a greater role in maintaining hold contact. So the question is how do we increase the contact force thus affecting the necessary increase of the friction force?  We might say that we that we grip the holds harder. The problem with this answer is that we grasp handholds using isometric muscular contractions. In isometric contractions the contraction is equal to the force it is resisting. So on a crimper, sloper, jug, gaston, pocket, etc a more forceful contraction will not increase the contact force on the hold, it would only mean that the hand would be prepared to resist a greater force. The only exception to this is pinches. The opposition between the thumb and fingers will increase the contact force, resulting in a greater friction.

Other than in the case of pinches, if gripping the holds harder will not increase the forces, how are greater forces generated?

In the case of the hands we use the rest of the kinetic chain to pull the hands into the holds with greater force. This is easiest to see in the example of side pulls. When using a side pull elbow flexion and adduction of the shoulder will increase the force at work on the handhold.

Elbow flexion and shoulder adduction in the left arm. Hold is a bad sloper on a steep wall.

In situations when the arm is straight, it’s more likely that pushing away from the hold with a foot will increase the forces. This action is common when doing laybacks. It’s also very common on steep face climbs to see a heel hook on one side of the body, used to increase the contact force on the hand hold on the other side of the body.

The situation is similar when considering footholds. It’s the joints of the legs that are used to increase the contact force. It’s plantar flexion of the ankle, extension of the knee and extension of the hip that tend to contribute to increasing the forces at work on footholds when the body is facing the rock.1 If the body is turned to the side, then the action of the hip joint favors adduction, but the actions of the knee and ankle will be the same since neither of these joints is capable of adduction.

These are just a few of many possible examples; the important point here is that large segments of the closed kinetic chain contribute to increasing the forces at work on foot and handholds.

So here is where we can articulate what body tension actually is. As stated in the last post Climbing consists largely of closed kinetic chain movements. The main purpose of which is to move/ position the COG through space and to facilitate a hand or foot reaching a new hold.  However, there are situations in which the closed kinetic chain is also engaged in the task of increasing the contact force on hand and footholds, for the purpose of affecting a proportional increase in the friction force. It’s the application of closed kinetic chains to both these tasks at the same time that is responsible for body tension.

 It’s probably the case that using the kinetic chain to increase the forces at work on holds is going to be enough to create the sensation of body tension. But I am interested in the ways the two different uses of the kinetic chain conflict with one another. Thus, the farther the COG needs to move in space, the more difficult it can be to maintain a sufficient friction force on the holds, especially the footholds. The corollary is that the more effort required to maintain adequate friction on the holds, the more difficult it will be to perform certain movements of the COG.

There are a lot of details that need to be noted. For example, just the movement of the COG in space is going to increase the contact force on some holds. A basic mechanical principle is that the closer the COG moves to a point of contact with a supporting surface, the greater the force applied at that point. Thus the forces at work on any point of contact during a move are dynamic. Sometimes they work in our favor but often they do not.

In addition, some configurations of kinetic chains are more common than others. For example, it’s often the case that the chain we are most interested in runs between the hand remaining in contact with its hold and a foot or both feet.  It’s the movement of the COG away from the footholds that’s instrumental in pulling the feet off the rock. It’s the climber’s job to increase the forces working on the footholds during the course of a move that is naturally reducing those forces.

In summary:

The main source of the sensation of body tension is most likely the need to apply the close kinetic chain to the task of increasing the contact force on footholds and handholds. The greater the effort necessary for this task, the more difficult it will be to move the COG through space. The conflict between the goal of moving the COG in space, and the necessity of increasing forces on the holds, which gives body tension moves their character and makes them so difficult.

This might all seem very abstract, so in the next post or two I will use photos and videos to show how these ideas apply to actual moves. I think the first video I want to present an analysis of is of Dave Graham on his V15 problem called The Island. You can see it here:

The Island V15

Create your own analysis and we can compare notes. Also, if anyone is still reading this post at this point; if you have good body tension video or stills feel free to send them along and I’ll try to present analysis of them.

Notes:

1. I think it’s likely that the trunk through extension, and shoulders through flexion can also participate in this action in some cases.

8 Responses to “A Theory of Body Tension: Tying the Concepts Together (Finally!)”

  1. ToddNo Gravatar says:

    Doug,

    I watched the video. This is a perfect example of the reason that I read your stuff. You give me the tools to be able to analyze these complex moves. After reading about using a closed kinetic chain to increase contact force, it just jumps out at me watching the video.

    The key seems to be the diagonal forces of the left foot/right hand and right foot/left hand to move the hand on the same side as the foot hook.

    0:20 – 0:22
    Notice the right toe hook increasing the force of the left hand. He can use this to move the right hand up and out.

    0:25- 0:32
    Again, a big right hand movement here so he hooks the right heel to oppose the force in his left hand giving a stable base to throw that right hand. Dave’s skill at placing that hand perfectly is a marvel to watch.

    0:34-0:43
    Look at all of this beautiful footwork just to get the left toe hook. This gives him the opposing force so he can make the left hand move up to the crimper.
    Doug: please give your thoughts on the left foot slipping off after the left hand is solid. I’m not sure if he does this purposely?

    0:46-0:53
    He wants to move the right hand so he places the right heel hook to oppose the left crimper.

    0:56-0:58
    The huge left hand move!! Look at the tension in his right arm! You can just imagine one long tendon going from that right hand through his hips down to the left toe. However, I don’t know what to think about that left toe slipping off again.

    Doug: Also, could you comment on the vertical hip movement? I note that he is throwing his hips up in the initiation of some of the movements and using body tension to control the descent.

    Thanks,
    Todd

  2. gNo Gravatar says:

    nice video analysis game.

    i’ll just focus on the big move finishing at 1:00

    the most interesting thing is the role of the right arm and hand, and especially the pulling direction: an “undercling” vector is developing through the movement.
    At the end of the move this “undercling” force vector helps increasing the contact strenght of the left hand and right foot

    another interesting point is that the right leg is fully stretched and the vertical projection of the COG is very far from the foothold. i have an hard time biomechanically explaining why, but empirically this situation will require greater-than-usual effort from muscles located in the lower trunk (probably glutes and lower back for this specific case).
    I think this is the feeling that most of us call “body tension”…

    i have a suspect that your body tension definition is much broader than the intuitive/implicit category that we can find in most climber’s brains…
    practically any move that is not straightforward pulling fits your category!
    though i’ve never heard anyone saying that most layback, offwidth, compression and stemming moves require/involve body tension…

    anyway, here’s a couple of moves that will hopefully fit everyone’s definition (?)
    http://vimeo.com/11028890#t=43
    (0:45 to 0:55)

  3. DouglasNo Gravatar says:

    Todd, thanks for the analysis, you bring out important points. I am glad you mentioned the hip movement and the toe hook because in my mind those are the most interesting moments in the video, so I will be digging into the details on those.

    G,

    I agree that you have identified the move that climbers would most often describe as body tension. I will also treat that move in detail as well. Please forgive the fact that I have held back a few concepts until the discussion of pragmatic examples. For example, I’ve said nothing yet of the length of the moment of force between the COG and footholds, but the length of the MOF in the move you describe is an important contributor to the sensation of body tension, and I can describe it in mechanical terms.

    My definition does end up covering a variety of situation. When doing movement analysis and trying to articulate a theory I think its important to examine the idea broadly and to ask myself “what else does my definition cover?” I’m not trying to blow the lid off of the definition of body tension but since I articulated a specific relation between the kinetic chain and the friction force, I couldn’t deny that laybacks function in a similar way.

    I hope its not the case that any move that “is not straight forward pulling fits my definition” because of what I said about the friction force. Think of it as a continuum based on how the climber feels. A move does not become a body tension move until increasing the forces at work on hand and footholds becomes an important priority for the climber or becomes difficult enough that it is in competition with the desired movement of the COG. As I lay out the examples, see if the definition doesn’t get more focused and specific. Also we need to keep in mind that there is a subjective component to body tension, as what counts as a body tension move for a V3 climber is not going to feel like a body tension move for a V10 climber because of his or her superior coordination and fitness.

    Anyway, I hope the examples will provide clarity and focus to the theory.

  4. Brendan NicholsonNo Gravatar says:

    Starting at 1:30
    https://vimeo.com/35330426

    Analyzed here:
    http://routecrafting.blogspot.com/2012/02/movement-analysis-gecko-assis-swinging.html

    Lots of subtle hip movements to get more friction on terrible holds.

  5. gNo Gravatar says:

    http://www.youtube.com/watch?feature=player_detailpage&v=00cQB4_pagY#t=217s

    interesting footage with several moves fitting broader and narrower ideas of body tension, and even more interesting commentary including lines as:
    “very few down-pulling holds”
    “…body movement, so that you can use these terrible handholds”

    It seems a practical summary of the original post, and also helps me to reformulate my affirmation that “practically any move that is not straightforward pulling fits the category”.

    I’d reformulate it as : “any movement on steep ground (ie at least vertical) that does not involve pinches or sub-horizontal, relatively incut holds”.
    (because then a considerable amount of energy will be spent only to generate enough friction and keep the COG in the right “path” for the move)

    btw i find that such relatively broad categorization has a merit: the common point between the possible different sub-categories is the need to build a “feel” for friction, body position, muscular tensions, and the relationships between these factors.
    It is nice to put this quality forward since, being a complex ability that is slowly build through…boring mileage on incfreasingly complex climbs, it is easily overlooked by the beginner and intermediate climber looking for rapid performance gains.

    On the other hand, subcategories might be helpful for advanced/elite climbers who do have an overall “feel” for these situations, with specific weaknesses…

  6. JeffNo Gravatar says:

    “A basic mechanical principle is that the closer the COG moves to a point of contact with a supporting surface, the greater the force applied at that point”

    Just wanted to point out that this isn’t always true. The climber in your video is actually a great example of why. He starts with a very wide base and the right hand and foot are along the edge of the rock and exerting a lot of medially directed force into the rock. If he were to shift his weight rightward, it would decrease his ability to generate force through the right side of his body

    At it’s most basic level, I think it depends on the angle of the hold. For holds that are horizontal, I think the statement is completely true. For holds that are more vertical, I would say the opposite (leaning or pullying the COG away creates more force).

    The major exception to that might be in situations where the body is oriented sideways and you are relying on what routecrafter’s article referred to as compression forces, then the opposite might be true.

    Looking at my two statements above, it occurs to me that it likely is a factor of 1) the angle of pull created by the climbers mass, 2) the angle of pull created by the climber’s movement effort, and 3) the angle of the hold relative to the net force created by 1 and 2 (not to discount friction).

    On a seperate note, it also occurs to me that if I stand on a large hold and have two good holds that I can apply a solid downward force through (horontal holds, jugs, etc) and they are maybe shoulder height, that this may also be an exception. While standing tall, these holds are of little use other than to keep me close to the wall – all of my weight is through the hold I’m standing on. However, if I squat down (moving my COG towards the foot hold) it allows me to generate more tension through the handholds, violating the priciple outlined above.

  7. DouglasNo Gravatar says:

    Jeff,

    Jeff, there is no disagreement here. You restate in your own words the same thing that I address in this post here:

    http://www.selfcoachedclimber.com/2013/01/body-tension-dave-graham-on-the-island-v15/

    The line you quoted is a general principle of balance, it is related to, but not the same thing as an athlete’s ability to actively apply force to a hold. If you read the post I referenced above I think you will see that we describe this in similar terms. Re-reading this post I realize that I didn’t really need to mention this principle at all and doing so created ambiguity. Sorry about that!

    There may be one point of difference in our thinking, and that regards the issues of weather or not changing the orientation of the hold changes the principle. We both agree that it is the case when holds are horizontal (hold surface more or less perpendicular to the force applied by the climber). When holds are vertical (hold surface more or less NOT perpendicular to the force applied by the climber), I think the principle still holds true but the climber just falls off because there is no good supporting surface to resist the increase in the force that results from the movement of the COG. I’d say this is the reason why, we both point to the importance of keeping the COG to the left in the Dave Graham video. We both agree that doing so does increase his ability to actively apply force to the hold.

    You write:

    “Looking at my two statements above, it occurs to me that it likely is a factor of 1) the angle of pull created by the climbers mass, 2) the angle of pull created by the climber’s movement effort, and 3) the angle of the hold relative to the net force created by 1 and 2 (not to discount friction).”

    I tend to agree with this. And I hope you can see that playing out in my description of the Dave Graham video.

    Thanks for the comments, I think you really point to some areas that I can improve in my writing so as not to create ambiguity. I would also be interested in your thoughts on my description of the Graham video.

  8. JeffNo Gravatar says:

    I’ll take a look at your other one again, I was reading everything in sequence so I hadn’t gotten there at the time of writing that. I’ll also look at the video and description again.

    going back to the princple with the orientation of the hold. My thought is this …. When I traverse at the gym I train at, I have a spot where the wall makes a 90 degree turn creating a convexity. Suppose as I approach the corner (on my right) I take my arm and am able to just reach to it with my right hand and stick the palm flat on the wall, and that my feet are on good foot holds of about equivalent height, one is very near the corner. At this point, I’m balanced to where I don’t even need the left hand. (If you’re not at the gym while reading this, just stand facing sideways in the doorway with your right shoulder slightly to the left of being in line with the doorframe/wall, your hand on wall the right side frame and feet on the left side)

    The most force I can place here is by maximally leaning leftward, away from the corner. As I pull towards my right, your principle holds true completely for my footholds, I will definitely place more weight on the right by shifting my weight there. As for my right hand, as I move to the right my COG gradually moves from being closer to, if not beyond my left foot towards the middle of my feet and my feet are now the primary contact points and I could stand without the right hand if the footholds are good enough – just as I can stand on the floor once I’m upright. If I continued to push into the wall and lean right, as my COG moves rightward towards my point of contact vs the wall, I would actually begin to get off balance and fall rightward.

    The reason I think I place more force on the handhold on my right as I lean left is because it is so effective at preventing me from actually falling leftward when my COG is all the way to my left, particularly if the COG is to the left of my left foot (and thus completely beyond the BOS). Without my hand I would fall.

    By contrast, if I had two horizontal edges (and there is nothing else to grasp on the hold, just the edge) roughly placed directly above the footholds, this same thing will not work (if you’re playing along at home, grab the top corners of the doorframe to simulate). If I maximally shift my weight to my left, I find myself placing more weight on my left hand and at some point invariably start moving my right hand leftward. I have an idea of why, but am not 100% certain. I can try to articulate it if you’d like.

    I’m also curious how it would change things if I took the left edge and rotated it leftward maybe 45 degrees, that might either cause me to just fall or use the right hand more.

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