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Forefoot Varus Wedges and Cycling Performance

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Apr 21, 2011.

  1. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1

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    CAN FOREFOOT VARUS WEDGES ENHANCE ANAEROBIC CYCLING PERFORMANCE IN UNTRAINED MALES WITH FOREFOOT VARUS?
    Nicholas J. Dinsdale & Alun G. Williams
    Sport Scientific and Practical Aspects; December 2010. Vol. 7, Issue 2
    Full text
     
  2. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    The authors clearly have no idea what forefoot varus even is:
    :craig::craig::craig:
     
  3. RobinP

    RobinP Well-Known Member

    Despite the obvious lack of correct terminology - assuming they are referring to ff supinatus, does it seem like a reasonably robust study?

    I'm not great at picking holes in studies/statistics etc but this would tie in clinically with what I have observed in the cyclists I have seen(admittedely not lots)

    Any comments?
     
  4. I started treating cyclists and teaching cycling biomechanics during my Biomechanics Fellowship back in '84 - '85. Varus wedges either placed inside the bike shoe or placed between the bike shoe sole and the cleat are modifications that have been used for at least the last 27 years to take a cyclist with an inverted forefoot to rearfoot alignment and getting them to function on the bike more normally.

    A little podiatric-cycling treatment history is in order here. At the time of my Biomechanics Fellowship, Harry Hlavac, DPM, who practiced about 20 miles away from CCPM in Mill Valley, was developing and patenting a new device he called the "BioPedal" which was a bike pedal that allowed the cyclist to either invert or evert the dorsal surface of the pedal in order to improve the cyclist's biomechanics. Unfortunately, for Harry and his Biopedal, this was also the time that clipless pedal systems were becoming popular which allowed us to simply wedge the bike cleat with a shim material, such as coins, washers or korex, to produce the same varus or valgus wedge effect for the cyclist without the expense and extra mass of the "BioPedal".

    Since that time, I have done demonstrations at one of the larger bike shops in Sacramento showing how using varus cleat wedges can improve the tracking of the knee during cycling in cyclists with inverted forefoot deformities. The effects can be quite dramatic in some individuals with highly inverted forefoot positions. Currently these wedges are available commercially which greatly simplify the alignemt process for the cyclist. The wedges can also be stacked together in neutral alignment for treating limb length issues in cyclists.

    http://priceforay.com/product/LEMOND-LEWEDGE.html

    http://www.specialized.com/us/en/bc/SBCEqProduct.jsp?spid=60163&gold_ses=

    In addition, two decades ago, I was a researcher in a bike study back with the Department of Mechanical Engineering at UC Davis that was eventually published in the Journal of Biomechanics (Ruby P, Hull ML, Kirby KA, Jenkins DW: The effect of lower-limb anatomy on knee loads during seated cycling. J Biomech, 25 (10): 1195-1207, 1992). In this study we used an instrumented bicycle pedal which measured forces at the shoe-pedal interface just like a force plate to determine which lower extremity measurements correlated to knee joint loads: STJ axis location and forefoot to ground alignment with the STJ in neutral position.

    Hope this helps.
     
  5. daisyboi

    daisyboi Active Member

    As a keen cyclist I have often pondered the perfect pedal design while cycling (it keeps the mind off the pain). I wondered if a forefoot valgus wedge would increase stiffness in the foot and therefore translate more power through the pedal. I am looking at this from an improved performance/power output rather than a biomechanical correction of pathology. Would it be likely to increase power output by placing a valgus wedge under the forefoot and what other consequences may result from this action?
     
  6. How?

    The thing with cycling is there are so many other variables to play with, not least crank arm length and gearing ratio's and obviously the weight of the bike (particularly rotational weight).

    It also depends on the type of cycling were talking about. In BMX racing, it's all about the snap at the gate and getting the holeshot at the start so you don't have anyone in front of you taking your line, falling off in front of you etc. So, acceleration is key. Traditionally 20" bmx ran a 44:16 gear ratio, with a 175mm crank back in the day, now equivalents of a 55 gear inch ratio (44:16) is still most commonly run, but commonly with a longer (180-182mm) crank arm.

    I run a 32:14 on my 24" cruiser, as I run a 175mm Shimano XTR crank (very light), I drop slightly under 55 gear inches to make up for the shorter crank to gain better acceleration from the gate. I use a ceramic bearing bottom bracket, my bike cost about £2K to build and I'm still rubbish. But it takes my mind off work and I enjoy it, when I get the time to go out on the track. It's my mid-life crisis.

    See here for more on gear ratio:
    http://www.profileracing.com/ht_gearinch.php
     
  7. efuller

    efuller MVP

    Tried it 20 years ago. Increased pronation moment from pedal around STJ axis. Either you let the STJ pronate, which makes it more likely that your medial maleolus hits the crank, or you hold the foot supinated with the posterior tibial tendon and with my extremely medially deviated STJ axis foot the post tib muscle gets very sore.

    Eric
     
  8. As Eric stated, if forefoot valgus wedging is used in the wrong cyclist, it can cause increased subtalar joint (STJ) pronation which will also lead to increased knee adduction during the power phase of cycling. However, I have used forefoot valgus wedging in cyclists that have an everted forefoot to rearfoot relationship and/or plantarflexed first ray with good success. Sometimes even the forefoot valgus wedge causes the STJ to paradoxically supinate more on the pedal.

    Another modification I have used are varus cleat wedges between the shoe sole and cleat with possibly a reverse Morton's extension and a medial longitudinal arch wedge inside the shoe. I believe that if you keep in mind that the goal of cycling is to make the foot and lower extremity function with a knee moving as staight up and down as possible, and make the rest of the lower extremity below the knee function just as if it had only an ankle joint and metatarsophalangeal joints, with no subtalar joint, midtarsal or midfoot joints, then the clinician will have a much easier time in understanding mechanically what must occur to have efficient cycling biomechanics.
     
  9. daisyboi

    daisyboi Active Member

    The reason I ask about forefoot wedging is that on a number of recent climb events I have been very aware of my forefoot "rolling acros"s the pedal as I try to climb aggressively. This feels like there is hardly any force through the 5th met and a vast increase through the first met as compared to cycling on the flat. At first I thought this was possibly due to poorly fitting shoes allowing too much movement so I experimented with a few different pairs but am now back to my original specialised shoes as changing didnt seem to make any difference. Changing my gearing from 54/11 to 54/13 meant a small decrease in this sensation until a recent climb in the Alps where it was more noticable than ever (but then the climbs were more severe than ever before!!). I have since asked a number of club members whether they are aware of a similar rotation when climbing and a significant proportion (more than half of a very small sample) feel the same thing. Because of this, I wondered whether placing the foot in this position for hill racing may mean increased efficiency rather than the foot having to work to get into this position with each revolution. I realise that this may mean other mechanical changes affecting the knee etc, but wondered whether it would be possible to make rearfoot posting adjustments to negate the effects on knee mechanics. I probably should have written all this the first time round!
     
  10. Quick question: when climbing how does your body position change? For example do you stay seated or get up out of the saddle?
     
  11. daisyboi

    daisyboi Active Member

    That varies a lot. on very short or very steep climbs I will be out of the saddle but on longer climbs I will try to stay in the saddle as much as possible as I find it helps maintain a good rhythm. Since changing my gearing I am in the saddle a lot more
     
  12. Daisy:

    You may try adding a reverse-Morton's extension to your bike shoe insole, made of 1/8" felt, to see it this allows the metatarsal head pressure pattern to improve inside your bike shoes. The increase in 1st metatarsal head pressure during climbs is likely due to increased activation of the peroneus longus muscle during more forceful pushing on the pedal during the power stroke. The reverse-Morton's extension should improve the power and comfort of cycling but may need to be also combined with a mild medial longitudinal arch support also inside the bike shoe to prevent excessive subtalar joint pronation.

    Hope this helps.
     
  13. efuller

    efuller MVP

    I was going to suggest the same thing as Kevin. My thinking is that you need more medial forefoot loading while keeping the STJ supinated enough to keep the medial maleolus from hitting the crank. Hence you get more peroneus longus activation and the sensation of rolling into pronation. A varus wedge that ends at the 2nd metatarsal is what I ended up liking in one particular pair of shoes.


    Peroneus longus: when there is resistance to 1st ray plantarflexion it will move the joint with the least resistance. So with resistance to first ray plantar flexion (force under the first met head) peroneus longus will create a pronation moment. If there is no resistance, or little resistance the first met will plantar flex and the posterior tibial tendon can easily hold the STJ supinated against the pronation moment form peroneus longus.

    Eric
     
  14. David Wedemeyer

    David Wedemeyer Well-Known Member

    I struggled with this issue myself for a long time Daisy (do you have another name we could call you?). A lot of the literature with regard to cycling addresses forefoot varus but very little forefoot valgus. True FF varus is rare and typically congenital or there is a supinatus, therefore I see mostly valgus issues and after spending some time here reading and learning began experimenting with cleat wedges, shoes and creative orthosis mods.

    I have a very high arch off weight-bearing and a flexible mid and forefoot. If you have read Kevin's papers on STJ axis rotational equilibrium, you understand the valgus attitude of my FF as a compensation in weight-bearing. It may be applicable to your concerns as well and explain the "rolling across the pedal" you describe?

    I changed my orthosis to reflect what Kevin suggested (valgus FF posting) and I'm near perfect comfort wise. Other fun things I did to the shell were to make it sulcus length, a deep heel cup, minimal arch fill to maintain the high MLA, a mild medial heel skive and first ray cutout. I call this the shotgun approach :D I chose a graphite blank and added neoprene atop 1/16 poron. It;s slimmer and slightly more flexible than my other orthoses.

    Cycling is similar to a perpetual midstance phase of gait and the increase in loading on the plantar fascia over time hurt like Hell after I got off of the bike, which was mediated by moving the center of pressure away from the medial plantar fascia via the ff wedge and skive. Your reference to gearing is interesting, perhaps increasing cadence in a lower gear requires less mashing on the downstroke, which also helped me; in fact it forced me to be more aware of my upstroke and knee alignment especially on climbs (where pretty much everything hurts ;) .

    I also bought a Bont shoe, wider toe box (I was experiencing numbness across to metatarsals) and they are heat moldable. I was using Nike shoe (curved last and I believe Specialized is as well?) and I can actually get the orthosis in my Nike shoe and wear it somewhat comfortably.

    I would try the cleat wedges that Kevin recommended and if valgus posting is of benefit, consider what can be done inside the shoe to decrease your symptoms.

    Best regards,
     
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