TWO RELEVANT FACTS ABOUT BIKE POSITION

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1. Quote: “Both of these muscle groups flex (bend) the knee in isolation. Working across the kneewhile the leg as a whole extends, the nett effect is to pull the knee joint backwards. In other words, the combined effect is to help the quadriceps extend (straighten) the knee.”

   I’m not sure I understand your logic here. Can you elaborate on how two different knee flexors can help extend the knee?

   1. G’day William,
      When next you ride your bike, place one hand on the belly
      of your hamstrings. You will feel it contract as the knee extends on the
      down stroke even though the hamstrings group are lengthening as a whole
      during the down stroke. I’m not asking you to feel your calves while you
      peda,l as doing so might be dangerous but I’m sure that you can see them
      contract on each pedal down stroke if you look. If you are riding behind a
      lean rider you will see their gastrocnemius tendon tighten on each pedal
      down stroke.

      Both muscle groups, hamstrings and gastrocs are pulling across the knee in
      opposite directions, leaving no alternative but for the knee to extend. I’m
      not saying that they do this in isolation, I’m saying that they do this in
      concert with the quads working to extend the knee.

      Here’s a thought experiment. Place 3 people in a triangle pattern. Have the
      two at the base of the triangle each tie a rope to the waist of the third at
      the top of the triangle. Then have the two at the base pull on their ropes
      hard. The 3rd at the peak will have no alternative but to move towards the
      base of the triangle until they are in line with the other two. The triangle
      will now be a straight line. Substitute the triangle for a flexed knee and
      the straight line for an extended knee and you will see my point.

      The key to this force couple is that both hamstrings and gastrocs *cross *the
      knee via their respective tendons.

      1. Steve,
         Thanks for the reply. In the interest of accuracy and clarification for everyone, I’d like to continue our dialogue on this topic.

         Knee flexors cannot extend the knee, even if done in tandem. Your hamstring evidence is simply the tension placed on the hamstrings during an eccentric (lengthening) load. The gastroc evidence you provide is simply the gastroc plantar flexing the foot in an effort to pedal. They are not actively straightening the knee. I would agree that they are possibly providing support, but I cannot accept that they straighten the knee.

         Your rope example, appears to be similar to cycling but has a fatal flaw. In the rope example, the rope is effectively shortening to bring the third person in-line. It is not possible for the hamstrings and/or the gastroc to shorten and bring the knee in-line. Just because a muscle is under load does not imply that it is shortening. A shortening hamstring will bend the knee and a shortening gastroc will likewise bend the knee.

         I agree with Nsantosmt (Nelson) and submit that the gluteal muscles are indeed, extending the hip at the same time as knee extension. It is simply an accessory movement that is inherent in the pedaling motion. However it coincidentally acts to supplement the quads.

         In the interest of all and with all due respect to you as a professional bike fitter, I’m curious to know how you arrived at the conclusion that knee flexors can extend the knee. I am not claiming a monopoly on knowledge here. I am only applying basic functional anatomy to a sport I love and attempting to open up an insightful correspondence with a blog I follow and respect. Again, my attempts to clarify this are sincere and please do not feel as though I’m attempting to raise a ruckus or be anything other than civil.

         Thank you and I anticipate your reply.

         Willie

      2. G’day Will,
         You’re being too polite. I am not easily offended and take your
         disagreement as a constructive one. I have no mortgage on ‘truth’ and am
         happy to have anything I say tested as that is the only way we ever learn.
         But thank you for being so polite anyway!

         I don’t disagree with Nelson about the role of the glutes in any way. The
         difference is that I said that two muscle groups; hamstrings and gastrocs
         which *individually *are flexors of the knee can work as extensors of the
         knee *in combination*. This is in addition to, not instead of, what Nelson
         has said about the glutes and quads role in knee extension.
         I need to say here that I have no formal training in any health science but
         have spent many years learning informally because bike fitting is a major
         interest of mine. What often happens is that I will come to some tentative
         realisation based on observation and then hit the books or tap any of the
         wide range of people I have met over the years for confirmation or
         otherwise. Sometimes I am right, sometimes I am wrong. Being wrong doesn’t
         matter to me as I learn something either way. Nelson knows me and will
         confirm that I’m an open minded person and not dogmatic.

         So what made me think that what I have described could be the case?
         Many years ago I found through much trial and error experimentation with
         clients, that a more rearward cleat position minimised quad tiredness and
         fatigue. Of course I wondered why. The tentative conclusion I came up with
         is that since the calves control movement of and stablise foot and ankle,
         and that limiting effective lever length of the foot by moving the cleats
         rearwards from BOFOPA reduced load on the calves, that this could only
         positively affect the quads ability to extend the knee before onset of
         fatigue *if the calves (in combination with hamstrings) were also playing a
         role in knee extension while pedaling.*

         When I first felt what I’ve stated to be the case, I went looking for other
         evidence or reference. The first I found was in a book named “The Anatomy of
         the Moving Body – A Basic Course In Bones, Muscles And Joints” by Theodore
         Dimon Jr. On page 211 in the bottom paragraph, and as part of a larger
         chapter named Muscles of the Thigh, it reads
         *
         *
         * “The third group of muscles is the hamstrings (Fig 79). The hamstrings
         flex the leg at the knee and extend the leg at the hip. When working in
         concert with the calf muscles, they can also act as extensors of the leg at
         the knee.” *
         *
         *
         The underlining is mine. I’ve had this discussion with a number of people
         since; biomechanists, an anatomy professor and various health professionals.
         While agreement wasn’t unanimous, it was the majority view of those I have
         spoken to. So my view seemed to me to be confirmed. That still doesn’t mean
         that it is correct, but I need to hear more as to why you think it is not

      3. Steve,
         Great response, thank you.

         However, I am left to wonder the fundamental question: how can an antagonist (hamstrings) shorten at the same time as the agonist (quads)? It appears that this would conflict.

         Unless it had to do with the dynamic nature of the pedaling motion and the loading/unloading phases of the muscles. For example, since the hip angle is changing at the same time the knee angle is changing then it would appear that there are going to be a different set of forces/muscle lengths at play here. But now I am just speculating and that’s quite often dangerous.

         This is where I can no longer add anything to the conversation. Thank you for your post, responses and professional courtesy.

         Willie

      4. G’day Will,
         I can answer your question, though the answer is not mine. I
         knew I had a second reference somewhere but didn’t want to mention what I
         couldn’t locate. I have just found it. It is in a book I recommend to anyone
         interested in how body functions dynamically. It is “The Anatomy of
         Movement” by Blandine Calais-Germain. If anyone reading this is interested
         enough to get hold of one, make sure you get the English translation, not
         the original French as I first did. Unless of course, you read French!

         On page 293 in the section The Ankle and Foot, subsection Extrinsic
         Posterior Muscles it reads……

         “Interestingly, when the knee is flexed and the leg and foot are bearing
         the weight of the body, the gastrocnemius and hamstrings combine their
         forces to become extensors of the knee, i.e., returning it to the anatomical
         position. When the foot is not bearing the body’s weight, these muscles act
         as flexors of the knee.”

         In the case of cycling, I would subsitute the phrase ” when the knee is
         flexed and bearing the weight of the body” with “when the knee is flexed and
         the rider is exerting force through the foot”.

         The other thing that may play a part is that in standing posture, the
         hamstrings and gastrocs function posturally. They are relieved of the need
         to help maintain an upright position when cycling because the weight of the
         body is supported by the position the rider holds, and so the hamstrings and
         gastrocs can function phasically and contribute to power production.

         Thank you for your courtesy and interest too Will. It has made me think
         about a few things in detail that I haven’t been forced to for a while. And
         hit the books!! Best wishes.

      5. I would like to add to this, in favor of Steve. People really do take the name of muscles and type of muscle atface value. The main thing people fail to realize is how intricate the Hamstrings are. It is one of the few muscles that cross 2 joints, that is why not only does it flex the knee, but also extends the hip. That is what you guys are missing. If you dont believe me go do a hard day of real squats, dead lifts and leg press, all leg extension/hip extension exercises and tell me how your hammies feel. The hamstring has several functions, it flexes the knee, extends the hip and helps hold the torso upright. The latter are its more important jobs. This is something widely misunderstood in lots of “american fitness” especially these days of every personal trainer with an online degree.

2. Hi steve,

   At this stage I’ve got to disagree with the concept that collectively the hamstring & gastrocnemius will straighten the knee with the appropriate cleat position.
   It is the gluteus maximus which extends the hip and in doing so will assist the quadriceps in knee extension during the downstroke phase of the pedalling action. Unfortunately in modern society with the amount sitting most of us do throughout the day at work or at home, we have lost the ability to activate this muscle to extend the hip and now overly realie on the quads to straighten the knee during cycling.

   1. G’day Nelson,
      Please see my answer to William.

      I agree largely with what you say re the gluteals because in too many people
      the gluteals are reciprocally inhibited by overly tight hip flexors,
      particularly the psoas. What I’m talking about is separate to that and does
      not contradict your 2nd and 3rd sentences in any way. When we pedal, it is
      in a closed kinetic chain because we have a pedal to push against. So
      gluteal inhibition doesn’t matter in the sense that we will not be able to
      pedal. We will be able to pedal as is demonstrated by the dysfunctional
      majority of cyclists every day. The action of the quads (and hamstrings and
      gastrocs) in extending the knee will generate movement at the hip with or
      without full involvement of the gluteals because it is a closed kinetic
      chain. The rider will even be able to put out the same power with or without
      full gluteal enlistment. What they won’t be able to do is sustain high power
      output for as long as they would if the gluteals were enlisted and
      functioning well, because they are using a lesser muscle bulk to achieve
      that power output. Localising the load equals lesser ability to sustain
      output.

      What I’m talking about is separate to this. The hamstrings and gastrocs both
      cross the knee. They are both tensioned during the pedal down stroke. They
      are both pulling in *opposite *directions across the back of the knee. They
      cannot but work to help extend the knee. This will happen with or without a
      good cleat position. What a good cleat position will do is reduce the need
      for the gastrocs (and soleus) to stabilise foot and ankle. This means that
      the calves, the smallest major muscle group required to pedal; the furthest
      from the torso and most affected by vascular compression, will be partially
      unloaded by a more rear ward cleat position. This in turn means that they
      will be able to keep up the force couple with the hamstrings for longer than
      would be the case with a more forward cleat position.

3. G’day both Will and Nelson,
   I have a large library that is always in disarray That means that looking for specific info can take some time. The answer to your query is called Lombard’s Paradox. Look up or google anything you can find and it answers your query Will, about agonist and antagonist action between quadriceps and hamstrings results in extension of the knee; and also yours too Nelson. Thanks to both of you for making me get off my backside.

4. Good morning from Germany,

   having thought about the problem of muscles doing extension instead of their normally function the flexion, I made up a theory by my one. I thought, that muscles can, under some neuronal circumstances, act the opposite way. We learned that muscles can have dynamic concentric, a static and dynamic eccentric action. When activated in the kinetic chain of pedalling, I thought that the hamstrings and the gastrocnemius act dynamic eccentric. In this case, they contract and give length instead of shortening. If this is true, they could push the knee in extension.
   Some time ago I´ve found a nice article about the paradoxon of lombard (but totally forgot about it). In this article the paradoxon is described in the action of pedalling, stair walking and so on. I will post a link. But it is in German. There is also a abstract in english.
   http://www.biowiss-sport.de/abstr5.htm
   This is the whole text in german: http://www.biowiss-sport.de/paradox.PDF

   It is interesting that the ischios can also act as a flexor in the hip…

   Hoping you understand my english and the explanation of my own made up theory, which turns out to be wrong.

   Greeting, Florian
   A german Physio, student in osteopathy and the science of sports.

   1. G’day Florian,
      Thank you very much for taking the time to send those
      links on. Also for your theory. I can’t remember who said it, but there is a
      quote somewhere that goes something like this “For every set of
      circumstances, there is a simple, logical theory that fits those
      circumstances perfectly, and that is totally and absolutely wrong”.

      I wouldn’t worry about it. You’re not the first and won’t be the last. At
      least you’re thinking about it!

      And your English is fine. This has been an interesting situation. When I was
      editing this post late at night, I clicked on ‘Publish’ rather than ‘Save
      Draft’ by mistake. I got quite shock when the next morning I see the
      unfinished post uploaded and both Nelson and Will politely taking me to
      task. I hurriedly added the images that were missing and then hit my very
      messy library looking for references that I hadn’t had to find for years.
      All in all a good learning experience for me!

      I knew that Lombard’s Paradox existed but couldn’t remember the name, as
      like you, I had forgotten. While chasing up the info, I found this as
      probably the least technical description
      http://moon.ouhsc.edu/dthompso/namics/lombard.htm

      To the Lombard’s Paradox, I would also add the contraction of the gastrocs
      for the same reason while pedaling. When the gastrocs contracts during
      plantarflexion of the foot, or contracts eccentrically to resist
      plantarflexion of the foot while pedaling, that tension also acts on the
      gastrocs tendons across the knee adding to the Lombard’s Paradox effect
      above the knee.

      At least that is how it seems to me until someone reading this can provide a
      better explanation if there is one.

5. Hi Steve and readers,

   This is super long – I apologise in advance, but I hope it at least provides some food for thought. (No questions here, by the way, Steve – just some ideas.)

   I’ve been thinking about the idea of the gastrocnemius and hamstring working together to help extend the knee for quite a number of hours while on my bike over the last few days. The idea doesn’t sit well with me, but I can’t prove it wrong. However, I would like to suggest a different way of thinking. (By the way, doesn’t Lombard’s Paradox refer to biarticular muscles which span the same two joints? Typical example – hamstrings and rectus femoris. I don’t think we can technically call any interaction between the effects of the hamstrings and gastrocs ‘Lombard’s Paradox’.) Also, Steve, I believe I understand your people-in-a-triangle analogy, but I’ve struggled to convince myself that it is an accurate analogy. Here’s my take on things Lombard’s Paradox-like…

   In the first quarter of the pedal stroke from top dead centre (TDC), the ideal direction of force on the pedal is some combination of forward and down – at a tangent to the arc that the crank makes as it turns. The quads are in a very good position to apply force to the pedals here as they will attempt to extend the knee, moving the foot forward. In the second quarter – from 3 o’clock to BDC – the ideal direction is some combination of down and back. However the quads, if they worked alone, would still be producing a forward force on the pedals – not back. So there’s a paradox here in the second quarter – even though we want to extend the knee to continue the pedal stroke, the reaction force on the pedals would suggest that we in fact need to provide a flexing force at the knee. (i.e., the reaction force vector passes in front of the knee.)

   Now imagine we tie a cable in the position of the hamstrings – or that the hamstrings contract isometrically. As the quads extend the knee, the cable/hamstrings will cause extension of the hip. The hamstrings have effectively transferred the force produced by the quads to a different joint – the hip. On the bicycle, our hamstrings can regulate the amount of force they produce, and therefore the amount of force transferred from the quads to the hip – and therefore the direction of force on the pedals. (The hamstrings actually lengthen during the downstroke, but the only relevant effect I see this having here is that they can do their job more easily as muscles can apply more force when contracting eccentrically than concentrically.) Nearing BDC, when our quads are extending our knee (good!) but are also pushing our foot forward in an increasingly ineffective direction (bad!), the hamstrings play an important role in directing the force we produce. (Of course, the gluteals are also extremely important here, and there are a lot of other smaller muscles involved, but I believe the idea still stands.)

   I don’t believe it’s correct to say the hamstrings help extend the knee. I’d say they in fact provide a flexing force at the knee. This tension in the hamstring is useful in that it helps extend the hip and therefore directs the force on the pedal in an effective direction.

   A similar idea: Doing a lunge in the gym – if the floor is slippery and we use our quads too much on the forward leg, our foot will slip forward on the floor and we land in a heap. Solution: use the hamstrings to oppose the quads at the knee, and at the same time provide a lot of help to the glutes in extending the hip, pushing the foot straight down into the floor, rather than forward. With good grip on the floor we can use our quads a lot more, and probably lift more weight. Of course, we have excellent grip on our clipless pedals, but using the quads to pedal with an overly-forward force on the pedals is probably not good, fatigue-wise, in any sustained efforts.

   Similarly, the gastrocs can transfer force from the quads to the ankle joint. As the knee extends, if the gastrocs act as a non-elastic cable, they will cause plantar flexion of the ankle. This idea is particularly useful when jumping. As the knee nears full extension, the speed of extension of the knee needs to increase greatly (exponentially??) to continue applying force before take-off. Then we’re left with a trade-off between jump height and preventing injury due to hyper-extension. Enter the gastrocs. The gastrocs will provide a flexion – not extension – force at the knee, serving to slow the rate of knee extension. The tension in the gastrocs will provide plantar flexion at the ankle, effectively transferring the work of our quads to the ankle. Additionally, due to the extending knee, the gastrocs will have a relatively lower speed of contraction compared to an imaginary gastroc which originates below the knee, leading to a better ability to produce force. The gastrocs are magic for jumping! Of course, we don’t jump on a bike, so maybe none of that really matters, except for giving another illustration of the ability of a biarticular muscle to transfer the force produced by a monoarticular muscle to a different joint.

   I’d like to look at what’s happening starting from the cleat. (When I first thought of this, it seemed too simple, but I can’t think of how to dis-prove the idea, so here it is…)

   Cleat more rearward →
   Less force production required by the gastrocs →
   Less flexion force by the gastrocs at the knee →
   Less extension force required by the quads.

   I would not say that the gastrocs assist in extension of the knee. In fact, I could even go the other way and say that in cycling – something which humans are not designed to do – the biarticular gastrocs are possibly a hindrance during the downstroke. (However I believe they are useful in the upstroke – particularly from BDC to around 8 or 9 o’clock– when used in combination with tibialis anterior.) I certainly agree that it’s good to have a cleat position which will not overly load the calf muscles.

   Some speculation: The lower flexion force by the gastroc at the knee leaves room for more flexion force to be applied by the hamstrings, and therefore more extension force at the hip. This may enhance the ability of the upper leg muscles to provide force to the pedal in the optimum direction, resulting in a smoother pedal stroke and lower muscular force peaks. Also, the less-used gastroc may be in a better position fatigue-wise to provide some flexion force at the knee at the beginning of the upstroke, again smoothing the pedal stroke.

   Well, that’s my 2 cents worth, or a little more. Comments, agreements, disagreements welcome!

   And thanks for the great website, Steve.

   Cameron

   1. G’day Cameron,
      Thanks for taking the time. A clarification, I wasn’t
      suggesting that the gastrocs / hamstring interaction was Lombard’s Paradox.
      At the start of Will’s 3rd post he posed the question:

      *”However, I am left to wonder the fundamental question: how can an
      antagonist (hamstrings) shorten at the same time as the agonist (quads)? It
      appears that this would conflict.”*

      My answer to that question was Lombard’s Paradox. As to the rest; I believe
      the case is much as I’ve stated but cannot prove it. If I’m wrong, I’m in
      good company as some of the people I have run this past in the past
      *should* know
      what they are on about. Equally, the only 2 books that I’ve found that deal
      with how human bodies move both state the same thing. That doesn’t mean that
      I’m right and it doesn’t mean that you are wrong either. In fact I really
      like your thinking and find it persuasive because you have fleshed out your
      argument in detail!!! And I’m sucker for a well reasoned argument.

      What it does means that there is an observable occurrence *(that moving a
      cleat rearwards delays or stops the onset of bad quad fatigue)* but debate
      about the mechanism. My view is simply that when there is contraction in two
      knee flexors; gastrocs and hamstrings, it has an effect on both attachments
      of each muscle which combine to produce an extension force across the knee.
      Your argument is much more detailed and I can’t see how to prove or disprove
      either. However you have got me thinking. I know a few people who *may* have
      the gear to test your hypothesis. I’ll ask the question and see if I can get
      someone interested.

      Lastly, thank you very much for taking the time to make such a detailed
      contribution to this debate.

      1. Thanks for reading and replying, Steve. If you can get any testing happening I’d certainly be interested in hearing how it goes.
         Cheers

6. Steve,

   I’ve been on the bike again today and had some more thinking time. I have been accused in the past of wasting time and brainpower thinking about useless theoretical garbage, but if you have the time and inclination…

   I’d like to share a few more ideas about the people-in-a-triangle analogy and your references.

   The triangle idea as you’ve stated it, I understand and agree with – the person in the middle will be pulled in line with the other two. But as soon as we move the attachment points from the pivot to points on levers either side of the the pivot (as is the case with the knee/hamstrings/gastrocs), can this same effect really still happen? I can’t help thinking that concurrent activation of the hamstrings and gastrocs cannot but work to help flex the knee, to use the same kind of expression as you. Say we connect the 2 rope-holders to the person in the middle with 2 metal poles. Then we tie ropes to the opposing pole – similar to the set-up of the gastrocs and hamstrings near the knee. Then the rope holders pull or their ropes – or even just 1 of them pulls; it makes no difference – the two rope holders will move together until they meet, i.e., the heel meets the buttock.

   Also, you say that these muscles are working in opposite directions. I think I see what you mean, but given their attachment points, in my mind, this only serves as evidence against your conclusion. The hamstrings pull up on the tibia – a flexion force at the knee. And the gastrocs pull down on the femur – a flexion force at the knee. Again, I’m struggling to imagine how these 2 flexion forces can help cause extension.

   Looking at the hamstrings in particular, let’s say they are in fact helping extension at the knee. I think we can assume that if they do not contract (have no tension) this help does not exist. We know that during the pedalling downstroke or walking up steps, etc, the hamstrings get longer. Does this mean that when the hamstrings contract they help themselves get longer?!

   Now, I say the answer to that question is ‘yes’. But – and it’s a big ‘but’ – this doesn’t happen by helping to extend the knee. It happens by helping to extend the hip.

   So the difference in opinions here could in fact just be a difference in wording, or it may come down to a recognition that the hamstrings and gastrocs help to extend the knee indirectly. They help to extend the hip and plantar flex the ankle, and in the downstroke or when stepping, jumping, etc, this results in knee extension in order to maintain posture, follow the pedal arc, etc. They assist the action as a whole (and play some vital roles in doing this (see my last post)) which leads to knee extension despite their application of force around the knee in the direction of flexion. Therefore, for my way of thinking at least, to say ‘they extend the knee’ or even ‘they help extend the knee when working in conjunction with other muscles’ is misleading and missing the vast majority of the story.

   I know you’ve found more support than not for your idea, Steve. I wonder if my ideas can bring more agreement between sides? Or, on the other hand, if these muscles really do have a more direct effect in knee extension than I’m suggesting, I would honestly love to understand it more. Do you have any other material/ideas/analogies to help me?

   Most importantly, Steve, feel free to spend your time doing more useful things than attending to this!

   Cameron

   1. G’day Cam,
      Thanks for giving me the option of not replying but given the time you’re putting into this I want to reply. Here’s where I think we’re at, and correct me if this synopsis doesn’t accurately reflect your view.

      We both agree that moving a cleat rearwards delays the onset of quad fatigue.

      I am saying that is because it reduces the role of the calves in controlling foot and ankle and hence reduces calf fatigue and that reduction means that the calves can better contribute to actively extending the knee.

      You are saying that the reduction in load on the calves by moving the cleat rearwards reduces a negative effect on knee extension that the calves play, hence reduction in onset of quad fatigue.

      I have come up with documented evidence to support my view; you have come up with a detailed argument to support your view leaving us in nett agreement with observed outcome (reduction in onset of quad fatigue) but a difference in explanations that may be anywhere from semantic to mechanical.

      I hope that is an accurate summary. Neither of us know how to further our views. I might (and this isn’t guaranteed) have a way. I have a long time friend arriving for a visit in a couple of days. He is a Professor of Exercise Science and has been involved with elite cycling on and off for a long time. He publishes a bit of stuff and in the past I’ve been able to get him interested in various matters that he has gone on to research and has published the results. I don’t know whether what we are talking about will attract his interest, but he’ll be staying at our place for most of this week and I might be able to soften him up after a few (real) beers.

      I’ll let you know the outcome of my softening up, either way.

      1. Sounds accurate to me, Steve.
         Speaking of beer, I had a La Trappe Tripel yesterday. Interesting…

      2. La Trappe. I haven’t seen one of theirs for a while. Not bad either though I
         always found their Tripel and Quadrupel at little on the sweet side. The
         Dubbel I liked but have never come across the Single.

7. When the foot is fixed in weight bearing, the gastrocnemius can help maintain knee extension. It does this when the hip and knee are in strong extension and when plantar flexion of the ankle is inhibited, such as when the line of gravity passes in front of the knee and ankle joints. Under these circumstances the gastrocnemius is able to pull back and down on the femoral condyles, thus contributing to knee extension.

   1. Thanks Andy,
      That sums up my understanding of the situation nicely. Cam
      differs in detail and offers a thoughtful argument to support his case.

   2. Andy, can I just confirm… Are you saying that a muscle (the gastroc) can apply a force about a joint (the knee), directly contributing to an action that makes the muscle longer? Before this discussion started, I would’ve said straight out that that’s impossible. Now I’m trying to convince myself that maybe it is possible.

      1. The phenomenon has pre conditions

         1. Plantar flexion of the ankle is inhibited = mid foot cleat placement with heel drop technique

         2. When the hip and knee are in strong extension = the gastrocnemius contraction will extend the knee only near the very bottom of the stroke ( with heel drop again )

         3. The saddle have to be in a setback position to prevent toe dip occur

         They all inline with Mr. Hogg’s bike fitting philosophy, we should stop doubting Mr. Hogg’s observation validity.

8. Hello Readers,

   from my educational view, I can support both variants. When the cleats are move more backwards, the gastrocnemius can use more force to flex the knee. Because he musn´t use his energy to stabilize the foot. Most cyclists are surprised, that they feel more tired in their lower calves when they use a more backward cleat position. This is given to the more phasic use of the gastrocnemius.
   You can also say, that the hamstrings help the quadriceps femoris extend the knee, because they extend the upper calf in the hip. So the parts of the hamstrings, which attach on the tibia can pull the knee backwards (in the direction of the rear wheel) and help the quadriceps extend the knee without using a flexing or extending force on knee. They hamstrings don´t actually extend the knee, but due to their extending force in the hip they give the quadriceps the ability to extend the knee in a better way.
   What Andy says is really a nice summary.
   The whole discussion says, that we don´t know enough of the human body to give a theoretical answer to a practical problem.
   More research would be nice.
   Greetings, Florian

9. G’day Steve and Everybody,

   Let’s take the example of an arm, because everybody will understand it. An example of PULL and PUSH. When we pull something, the angle of our elbow gets smaller, and the biceps is working. When we push, the angle gets bigger, and the triceps is working. Although we are used to think in “pushing” and “pulling”, actually the muscles are working ONLY by pulling, by contracting! If the force of the muscle is bigger than the resistance, then the muscle itself will shorten; if the force is equal, then it will have the same length; if the force is smaller then it will lenghten. BUT, everytime the muscle acts with a contraction. This is how i see…

   So, i realy do not understand how a muscle (gastrocs/hamstrings) that is design to shorten an angle (back of the knee) can do the opposite…

   I like a lot Cameron’s ideeas, that gastrocs and hamstrings can work as a cable, interesting… The lunge-gym example, “pushing the foot straight down into the floor, rather than forward”… nice… 😉

   …I think/feel like they (gastrocs/hamstrings) do not produce power, they maybe just assist/transfer it elsewhere…

   Regards,
   Mircea

10. G’day Cam and others if anyone is still interested in this. I mentioned a friend visiting who is a well credentialled exercise scientist. He didn’t want to buy into the discussion but put me in touch with a well known Professor of Biomechanics that I hadn’t spoke to for years. So Cam, I put both your and my arguments to him and he said that both have merit but that there is no definitive answer and much depends on the circumstances, as Andy has mentioned. He also reminded me that the hamstrings do not act as a flexor of the knee in anything resembling locomotor activity. They only act as a knee flexor when not bearing weight.

    I’m mentioning this as I had promised to get back to you, but unfortunately, this doesn’t further either opinion.

    1. I was thinking about following this up, Steve, but figured you would have let me know if anything came of it. Thanks for thinking about it again, anyway!
       Following on from what the professor said, I have a couple more points I could add.. but I’ll resist. Your website is full of practical information. This discussion isn’t. So I’ll leave it here.
       Thanks again for your efforts!
       Cam

       1. G’day Cam,
          You’re welcome. I probably get as much fun out of nutting this sort of thing out as you do.

11. Hi Steve
    Having reacurring problems with soreness along inside of the thigh ( follows the line of the adductor muscle down to the knee) when i am trying to increase workload on the bike. Occurs predominantly at the beginning of a ride and is sore for up to 30 mins, gradually wears off when i lessen the load ( drop down gears ) but appears again when I put in a sustained effort. Notice bruising on the insides of my thighs some days later after completing long rides. Had physio in April, given exercises to do to strengthen the hamstrings. Time off bike in summer helped but now back in training the problem has come back. Appreciate any advice.

    Rupe.

    1. G’day Rupert,
       On one or both sides?
       If one side only, which?

12. hi steve

    Thanks for your reply – predominantly left leg, although had one small similar problem on right leg but that has healed.

    1. G’day Rupert,
       There are several likely reasons and combinations of
       reasons. The background to adductor pain on a bike is that the adductors will only fire up if the pelvis is not stable on the seat. The adductors can function as a subsidiary pelvic stabiliser in an attempt to regain on seat stability. So why is your pelvic unstable?

       The most likely reasons are –
       1. Seat too high. The greater incidence on the left leg makes this likely. If the seat is too high, no one sits squarely on the seat and equally overextends each leg. The favour one side (usually, but not always the right – read the Right Side Bias) by hanging towards that side and sacrifice the other side (usually but not always the left). Also read the 2 posts on seat height. If seat height is the issue alone, it is probably at least 10mm too high.

       2. Too tight in the external rotators of the hip. Do you have to pull your knees towards the top tube to stop them from splaying out?
       If so, you are using your adductors to do this and need to tackle the root cause reasons for the knee splaying. If you are doing this, then you are likely extremely tight in the hips and lower back. If so, freeing up that area will take a while. In the meantime you will need to look at longer than standard pedal axles or the addition of pedal spacers to move your feet out under your knees.

       3. Seat setback. If either 1, 2 or both is the reason but not the full
       story, having the seat markedly too far forward or too far back can
       exaggerate any challenge to the stability of the pelvis. If you think this
       is possible, read and act on the posts on Seat Setback.

       4. Much like 3, too great a reach out or down to the bars can exaggerate a
       pre existing problem. Again, there is a post on bar position.

       Best of luck.

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