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Effects of orthoses on muscular activity and lower limb alignment while cycling

Discussion in 'Biomechanics, Sports and Foot orthoses' started by defalbaire, May 16, 2010.

  1. defalbaire

    defalbaire Member

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    I've just finished a study on normal insoles and the impact on cycling.

    Two pairs of insoles one with 100% of correction (Neutral Position) and one with 150% of correction were made with Cad Cam.

    Impact on muscular activity: EMG: Vastus lateralis, Vastus medialis, Biceps femoris and semi-tendinosus. (mean 30secondes)

    Impact on lower limb alignement: Dart fish: 3 points, extremities of the patella and the tibial tuberosity. The lower angle was studied.


    Significant effects on the muscular activity (Positive and negative)

    No significant effect on the Lower limb alignement

    :confused: I can't really understand how they can be flagrant muscle activity changes and no lower limb alignement changes?? I thought both were related?

    Can you help me finding a conclusion?

    1- The protocol with the 3 points is not representative of lower limb alignment? We should have done bisectors?? A point can stay fix even if there is a rotation?

    2- Insoles have limited the mouvements of the feets in the frontal and transversal plans (pronation). In walking this will cause a repercussion on le lower limb alignment but in cycling maybe it's different?

    Other ideas??

    Thank you for your help

    I can give you more informations if you whant!!

    Best regards

  2. Re: Effects of orthoses on muscular activity and lower limb alignment while cycling!

    Hi have you written up the study ? If so it might be good to post it up then. There is a big pink Elephant with what you wrote about 100% control, neutral position but if we push that aside for a while.

    So if you want post up what you have written up, maybe some data as well.

    also were the device posted with any forefoot postings ?
  3. defalbaire

    defalbaire Member

    Re: Effects of orthoses on muscular activity and lower lim alignment while cycling!


    My study is actually written in FRENCH. I don't have enought time to translate all of it!!

    For the correction: I defined 100% of correction as the neutral position, and so 150% is neutral position plus 50% from Root calculation! Does that still don't make sense for you??? :pigs:

    For the results you will see that I have actually tested only 3 subjects on the 15 subjects measured.

    The results are in attachements as well as the writting but in French if you understand it!!

    View attachment EMG.bmp

    Hope you will be able to help me and your personal reflection will be appreciated.



    Attached Files:

  4. defalbaire

    defalbaire Member

    Re: Effects of orthoses on muscular activity and lower lim alignment while cycling!

    sorry for the second Table it's the calculation of the lower angle made by the two points on the extremity of the pattela and the point on the tibial tuberosity!

    It's in degrees! The same angle as been calculated 3 times to see % of error of the measure!

    If you have any question?
  5. defalbaire

    defalbaire Member

    Re: Effects of orthoses on muscular activity and lower lim alignment while cycling!

    also were the device posted with any forefoot postings ?

    The first objective was to see If a rear foot correction (but with a total insole) had an impact as a lot of studies use forefoot corrections in cycling.

    We also studied a cluffy wedge of 8mm to compare with an other study who used the same parameters.
  6. Re: Effects of orthoses on muscular activity and lower lim alignment while cycling!

    it is sounds like you really don´t want any help, pretty rude response.

    You should do some reading on STJ neutral measurments.

    But Good luck :pigs::pigs:
  7. defalbaire

    defalbaire Member

    Re: Effects of orthoses on muscular activity and lower lim alignment while cycling!

    NO I'm sorry!!!

    I can't express myself very well in english and I sincerely didn't whant to be unpleasant!!


    I would like that you explain me what is wrong with my % of corrections. I don't think that what i've writting is necessarily thrue.
  8. Admin2

    Admin2 Administrator Staff Member

    Re: Effects of orthoses on muscular activity and lower lim alignment while cycling!

    Related threads:
    Other threads tagged with cycling
  9. CraigT

    CraigT Well-Known Member

    Hello Valery
    I think one thing you need to consider is that just because there is no change is position, is does not mean there is no change in forces.
    If you were to try and lift up a weight which far exceeded your ability, you would not see any movement. If the weight had a force value of 200N, and the most you could lift was 150N, then you would not lift the weight... but the force the weight put on the ground when you were lifting would be less- it would be only 50N (very simplified...). So you would not have seen movement, but there is certainly a change in forces.
    This is significant with orthoses as evidence suggests that forces are more significant when considering injury rather than movement.
  10. Ok Valery,

    lets try this again.

    Is off there are many issues with measurement of STJ neutral and correction angles. There has been much written about this here and in Journals. This is one reason why STJ neutral is being moved away from as a point of reference.

    So as I don´t speak or understand french. Lets look at your methods. In each test how did you determine how much energy/force each person was using ?

    In this day and age the watt meter is used by pro´s and coaches to determine how hard the cyclist is working and how their training is going.
    So on tv during a time trial say like the giro on Saturday last week, we ( the people watching)would all look at the km/hour and time as the most important thing, but on the riders bike the most important measurment is in watts.

    So in your experiment for each test to determine that each subject is the same as the control test.

    you would need RPM and Watts as Graig suggested just because the muscle work is going up it does not always mean a change in joint angles. They maybe just working harder.

    VM = Vastus medialis VL= Vastus lateralis ST = Semitendanosus and BF = Biceps Femoras. If the work of these muscle has increased the same % then then joint will still be in the same position there would need to be a change in one group say the quads and and not the other. You did say positive and negative but did not say which way for each muscle.

    Also think about cycling the foot is quite fixed and good cyclists the hip as well, the knee and lower limb works like on old steam train wheel it should follow the same action, if it deviates from here there will be a loss of power - ie watts produced.

    Also to get an orthotic to work you must have downward force. ie forces will be equal and opposite. In cycling most of the weight in on the forefoot so the downward pressure will be much less on the rearfoot and arch area, but what you maybe changing is the stimulation of the Central nervious system. Ie the skin is able to provide more feedback due to more area of stimulation. This is something I´ve been thinking lots about when out cycling over the last month. but don´t think to much into this

    Theres some stuff for you to consider and answer.

    Hope that it helps
  11. defalbaire

    defalbaire Member


    Thanks for your responce and the reflections you bring.

    Concerning the methods, I actually didn't use the watts, only the speed and the same gear. So the subject had to choose a gear and a speed then keep the same gear and the same speed for the 4 test. So the cadence was the same but I agree the watts could have change. I wanted to study the watts but unfortunately the RPM wasn't working!!

    The % of variation of the muscle activity between different muscle and two variable are not the same but maybe the other muscles who haven't been studied compensate the differences.

    Thanks a lot for the time you spend to reply!
    This helped me and open my vision!

    Have a great week

  12. David Smith

    David Smith Well-Known Member


    To add to what Mr Weber and Craig T wrote and making the assumption that each electrode is only measuring motor unit action potential (MUAP) signal output from the muscle of interest; also you should remember that there is no direct correlation between EMG peak muscle motor unit signal and total maximum muscle force and/or change in muscle length.

    What you are measuring is the change in potential between two electrodes so this gradient, from positive to negative, can become steeper without the actual Electrical signal from a motor unit being higher.

    There are many reasons why the MUAP is not related to muscle force and you need to be aware of these before you try to analyse the data from EMG.

    At the very least you should have a baseline signal to compare with the experimental signals using some protocol like max voluntary isometric contraction (MVIC) signal.

    Have a look at this site http://moon.ouhsc.edu/dthompso/pk/emg/emg.htm

    Also I have attached some papers that might interest you.

    Another thing to consider is that you have only evaluated 3 subjects, this is very weak in terms of statistical power and the probability that these three represent the population is low. In other words your results may not be representative of the changes that actually occur in a population of interest.

    Cheers Dave Smith

    Attached Files:

    Last edited: May 17, 2010
  13. Jeff Root

    Jeff Root Well-Known Member

    Re: Effects of orthoses on muscular activity and lower lim alignment while cycling!

    There is no way to measure the actual range of motion (rom) of the stj. We can only measure the frontal plane component of stj motion. However, if you measure the full rom of the stj in the frontal plane, then you can get a percentage of the total motion or select a point within the rom of the joint. The neutral position of the stj is approximately 33 percent from the point of maximum stj pronation. However, this is just a theoretical concept and the actual point of the neutral position of the stj must be individually determined. This is a clinically identified position and not an absolute science.

    Root chose the neutral position for casting and manufacturing most (but not all!) functional orthoses through trial and error, not because there was something magical about the neutral position of the stj. One reason he selected the neutral position was because he felt that he and other clinicians could clinically identify and reasonably place the foot in this position, as compared to say five degrees inverted from neutral which would require a measurement to verify.

    To assume that neutral is 100 percent of correction is somewhat misleading. There are a lot of orthotic manufacturing variables than can increase or decrease stj supination and pronation moments. For example, the amount and types of cast modifications can have a big influence on stj moments even when we don’t alter the frontal plane position of the cast (i.e. heel bisection) in the manufacturing process. For example, let’s say we take a cast and correct it to heel vertical. I could use liberal medial and lateral plaster expansion and generous fill plantar to the metatarsals. This would likely make the device less controlling. Conversely, I could take the same cast and use minimal cast modification and create a device that is highly conforming to the foot in the corrected or balanced position. This would probably create a device that would be much more controlling. Therefore, you can alter the level or percentage of control without altering the frontal plane position of cast.

    The functional orthosis was developed to reduce pathological forces. No one knows what percentage change or reduction in those forces is necessary to provide symptom resolution in any given individual. Merton Root believed that the foot that functioned maximally pronated during propulsion was likely to be subject to more severe pathology. He stated that if we could stop those last few degrees of pronation, then we would probably be doing the patient a great service.

    The concept of “control” is a little erroneous. We would be better off thinking in terms of orthotic “influence”. For example, our orthosis could have no change in the total rom of a joint but it could alter the position of motion. Or, our orthosis could reduce the tensile forces on the plantar fascia without any measurable change in the position or motion of the foot.

    I know this doesn’t really answer your question, but I hope it adds to the understanding of what orthoses are intended to do and why.

  14. daveeardley

    daveeardley Member

    Hi, must confess I am a little confused by your table, is the tibial tuberosity angle just at the top of the stroke? When I assess cyclists the biggest change I tend to see is not only the angle that the tibia has subscribed in the down stroke using tracking of the tibia, but in the ellipse that the tibial tuberosity subscribes through its track. So when reducing pronation via forefoot posting, this ellipse becomes more vertical in the frontal plane and narrower. To reduce that pronation I often find that external wedging under the cleat is overkill and can easily cause the knee to move away or abduct from the midline of the bike, often just a small wedge mets 2-4 is sufficient and then it should be lying just behind the centre of the met heads.
    I agree that a power meter woud be useful in quantifying the measurements, but experienced cyclists spend many hours on a constant effort so are quite good at judging a constant output.
    The tool I find most useful for cyclists is pedar in-shoe measurement, then you can see where the force is going and for how long.

    David Eardley
  15. daveeardley

    daveeardley Member

    [Check4SPAM] RE: URL Attempt

    One more thing Valery, what has been the previous reason on using the cluffy wedge. Sometimes it can be useful when one foot is producing less force and can engage the windlass and make the foot more rigid and so up the power. One thing that fascinates me is the forefoot angle of riging cycling shoes. This tends to be around 20 degrees, why? I have yet to see a study that states the average person passes through something approaching mid point of stjt and talar-crural at 20 degrees of hallux dorsiflexion and/or the plantar fascia has reached optimal tension to enable the power of the cyclist to be not wasted. Please educate me if anyone knows otherwise.

    David Eardley cyclingdynamics.co.uk
  16. efuller

    efuller MVP

    Last edited: Aug 7, 2012
  17. efuller

    efuller MVP

    Re: [Check4SPAM] RE: URL Attempt

    There are many structures in the foot that can resist dorsiflexion of the forefoot on the rearfoot. In cycling, the force on the pedal is usually below body weight and significantly below what the forces are in running and jumping. A cluffy wedge may change something, but the vast majority of feet should be rigid enough to handle the forces generated in cycling. So, I doubt the effect of the cluffy wedge is to change the foot from not rigid enough to rigid enough.

    The 20 degree angle on the forefoot may have more to do with walking when you are off of the bike than any effect when you are on the bike. These shoes are quite rigid and hard enough to walk in.

  18. NewsBot

    NewsBot The Admin that posts the news.

    Effects of Arch Support on Leg Muscle EMG and Performance in Experienced Cyclists
    Jordan Hirsch, Cole Meyers, Elise Caldwell, Moataz Eltoukhy, Ryan Pohlig, Joseph Signorile.
    Presented at the ACSM Meeting; San Diego May 2015

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