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The Effects of Orthotic Heel Lifts on Achilles Tendon Force and Strain During Running.
Farris DJ, Buckeridge E, Trewartha G, McGuigan MP. J Appl Biomech. 2012 May 8.
Quote:
This study assessed the effects of orthotic heel lifts on Achilles tendon (AT) force and strain during running. Ten females ran barefoot over a force plate in three conditions: no heel lifts (NHL), with 12 mm heel lifts (12HL) and with 18 mm heel lifts (18HL). Kinematics for the right lower limb were collected (200 Hz). AT force was calculated from inverse dynamics. AT strain was determined from kinematics and ultrasound images of medial gastrocnemius (50 Hz). Peak AT strain was less for 18HL (5.5 ± 4.4%) than for NHL (7.4 ± 4.2%) (P = 0.029, effect size (ES) = 0.44) but not for 12HL (5.8 ± 4.8%) versus NHL (ES = 0.35). Peak AT force was significantly (P = 0.024, ES = 0.42) less for 18HL (2382 ± 717 N) than for NHL (2710 ± 830 N) but not for 12HL (2538 ± 823 N, ES = 0.21). The 18HL reduced ankle dorsi-flexion but not flexion-extension ankle moments and increased the AT moment arm compared with NHL. Thus, 18HL reduced force and strain on the AT during running via a reduction in dorsi-flexion which lengthened the AT moment arm. Therefore, heel lifts could be used to reduce AT loading and strain during the rehabilitation of AT injuries.
In this study, a modeling method was developed to estimate Achilles tendon forces in running. Owing to the common use of heel lift devices in the treatment of Achilles tendon injury, we investigated the influence of increased heel lift on Achilles tendon loading. The hypothesis was that heel lift manipulation can influence maximum Achilles tendon force. Responses to heel lift variation were found to differ among 3 elite runners demonstrating distinct running styles. A rearfoot and a midfoot striker demonstrated significant increases in maximum Achilles tendon force with increased heel lift, whereas a forefoot striker demonstrated no changes in maximum Achilles tendon force values with heel lift manipulation (p < .05). Analysis of the factors contributing to the observed changes in maximum Achilles tendon force highlighted the influence of the moment arm of ground reaction force and the moment arm of the Achilles tendon about the ankle joint center. The finding that increased heel lift may increase maximum Achilles tendon force suggests that caution is advised in the routine use of this intervention. The different responses to heel lift increase between subjects highlight the importance of classifying subjects based on running style.
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by davidh
And of course this "Therefore, heel lifts could be used to reduce AT loading and strain during the rehabilitation of AT injuries".
To which the only sensible response is No sh*t Sherlock!
Well, you say that, but Sharon Dixon's study which admin posted above concluded the opposite: "The finding that increased heel lift may increase maximum Achilles tendon force suggests that caution is advised in the routine use of this intervention."
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
How did the moment arm of ground reaction force and the moment arm of the Achilles tendon about the ankle joint center change from the no heel lift to heel lift in the rearfoot/midfoot strikers? Don't need a diagram, thanks, mark
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by markjohconley
My query is how do we get a 18ml heel lift in a shoe?
Without wishing to cast nasturtiums upon your professional expertise I must admit to shock at the self imposed limitations expressed in your comment above.
Personally I have never had any problem getting an 18mm heel lift in a shoe and I am sure that, at a push, I could get a 15cm heel lift in a shoe. But then again size isn't everything.
I may be forced to retract my above comments as I have just realised that you are not using a linear measurement to describe the heel lift but volume. Unfortunately I am not up to speed on the novel concept of volumetric heel lifts.
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by Simon Spooner
Well, you say that, but Sharon Dixon's study which admin posted above concluded the opposite: "The finding that increased heel lift may increase maximum Achilles tendon force suggests that caution is advised in the routine use of this intervention."
I know, but there's a big "could" in my quote.
"Therefore, heel lifts could.... etc".
Sharon Dixon et al's study was carried out on a cohort of 3, with different running styles. I find it faintly ridiculous that anyone could base printed clinical advice, even if it contains the words "caution" and "advised", on a cohort of 3. Mind you, this was over 20 years ago so those researchers may have had a rethink since then.
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by wdd
Without wishing to cast nasturtiums upon your professional expertise I must admit to shock at the self imposed limitations expressed in your comment above.
Personally I have never had any problem getting an 18mm heel lift in a shoe and I am sure that, at a push, I could get a 15cm heel lift in a shoe. But then again size isn't everything.
I may be forced to retract my above comments as I have just realised that you are not using a linear measurement to describe the heel lift but volume. Unfortunately I am not up to speed on the novel concept of volumetric heel lifts.
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by davidh
Who reviews these papers.
The cohort is too small to derive any meaninful conclusions.
Foot types (ie tight post muscle groups) were not distinguished between.
And of course this "Therefore, heel lifts could be used to reduce AT loading and strain during the rehabilitation of AT injuries".
To which the only sensible response is No sh*t Sherlock!
Quote:
The 18HL reduced ankle dorsi-flexion but not flexion-extension ankle moments and increased the AT moment arm compared with NHL. Thus, 18HL reduced force and strain on the AT during running via a reduction in dorsi-flexion which lengthened the AT moment arm. Therefore, heel lifts could be used to reduce AT loading and strain during the rehabilitation of AT injuries.
What is interesting is the difference that was found in the reason for tension reduction as compared to what has been classically taught. The classical reason was that the lift takes the tendon off "stretch". The study found, from my understanding of the abstract, was that the decreased tendon load came from an increase of the lever arm of the tendon at the ankle joint. The plantar flexion moment was the same.
The plantar flexion moment being the same makes some sense because the task of walking may use the same amount of ankle push.
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by efuller
What is interesting is the difference that was found in the reason for tension reduction as compared to what has been classically taught. The classical reason was that the lift takes the tendon off "stretch". The study found, from my understanding of the abstract, was that the decreased tendon load came from an increase of the lever arm of the tendon at the ankle joint. The plantar flexion moment was the same.
The plantar flexion moment being the same makes some sense because the task of walking may use the same amount of ankle push.
Eric
N = 10?
Can't get any meaningful data from such a small sample (IMO).
Researchers may be directed to other research, or an extended study using the same methodology, but this study on it's own doesn't tell us anything much.
The paper should be renamed: The Effects of Orthotic Heel Lifts on Achilles Tendon Force in a titchy cohort.
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by davidh
N = 10?
Can't get any meaningful data from such a small sample (IMO).
Researchers may be directed to other research, or an extended study using the same methodology, but this study on it's own doesn't tell us anything much.
The paper should be renamed: The Effects of Orthotic Heel Lifts on Achilles Tendon Force in a titchy cohort.
David:
What is better, Davis, no data because no one took the time and effort to do even a small study, or a research study with only N=10?
Even research projects with large cohorts of N=200, can produce meaningless results if not designed properly. For this reason, I won't dismiss a study with only N=10, if the study was designed well and if the research studied a meaningful clinical question since I know how much time and effort is required to perform even a small study such as this..... it is much better than no data at all.
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by efuller
...was that the decreased tendon load came from an increase of the lever arm of the tendon at the ankle joint. ...
I've been playing with my skeleton and it's easier to imagine a DECREASE of the lever arm of the AT relative to the ankle joint. What am i missing? thanks, mark
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by Kevin Kirby
Even research projects with large cohorts of N=200, can produce meaningless results if not designed properly. For this reason, I won't dismiss a study with only N=10, if the study was designed well and if the research studied a meaningful clinical question since I know how much time and effort is required to perform even a small study such as this.....
Well, I kind of agree with this, but the results would have been far more meaningful if the cohort had been much larger.
As it stands it may be a good starting-off point, but as a piece of stand-alone research it's pretty light.
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Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by markjohconley
I've been playing with my skeleton and it's easier to imagine a DECREASE of the lever arm of the AT relative to the ankle joint. What am i missing? thanks, mark
The lever arm of the tendon is determined by the perpendicular distance from the line of action of the force (direction of pull of the tendon) from the joint axis in question. Schematically, you can model the foot as a triangle with one side of the triangle on the ground. The ankle axis would be at the angle opposite the side on the ground. The Achilles tendon will pull upward, mostly so the direction of pull will stay pretty close to the same. However as you rotate the triangle, into plantarflexion, around the ankle joint axis and extend a line vertically from the attachment of the Achilles tendon, the distance from that line to the axis will be greater.
Not at my home computer with line drawings that might help. Hope this does.
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by davidh
N = 10?
Can't get any meaningful data from such a small sample (IMO).
Researchers may be directed to other research, or an extended study using the same methodology, but this study on it's own doesn't tell us anything much.
The paper should be renamed: The Effects of Orthotic Heel Lifts on Achilles Tendon Force in a titchy cohort.
I wouldn't dismiss this study for the small N either, especially since it makes sense. I've always had a problem with the lift takes the tendon off stretch explanation because the tension in the tendon comes more from active contraction of the muscle rather than passive tension at the end of excrusion of the tendon.
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
bloody hell
now we are dealing with a short leg= SIJ problems and L5 facet disease
as well as poor knee extension control
keep going and we will all be the from end of the wheel barrow race without a euro.
hell I should not have said that
oh well, up the aussie dollar (for what it's worth)
night time here, weather beautiful
great place to live
regards
Paul Conneely www.musmed.com.au
stop being so serious. it makes life easier and more enjoyable.
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Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Paul,
From my clinical guidelines, I always apply a heel lift to both limbs to keep limbs as level as possible at pelvic level, and time of treatment with heel lifts would be kept to the minimum time to recover from AT injury.
How long in heel lifts would be required for L5 facet disease?
thanks
Vaughan
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Quote:
Originally Posted by ackers
Paul,
From my clinical guidelines, I always apply a heel lift to both limbs to keep limbs as level as possible at pelvic level, and time of treatment with heel lifts would be kept to the minimum time to recover from AT injury.
How long in heel lifts would be required for L5 facet disease?
thanks
Vaughan
Dear Vaughan
Hi, a very good question indeed.
Children with slipped femoral epiphysis can develop the problem with 10 years.
I am presuming the soul is older and if they have some degenerative disease process going on it will accelerate it within a matter of weeks.
I have seen this in a 54 year old male a few weeks back.
They felt a twinge within 2 days of a 10mm lift.
Radiology shows moderate disease.
It was there, but did not need much to start it become a pathology
Regards
Paul Conneely
Re: The Effects of Orthotic Heel Lifts on Achilles Tendon Force
Sorry, a bit late coming to this:
Quote:
Originally Posted by davidh
The cohort is too small to derive any meaninful conclusions
Quote:
Originally Posted by davidh
N = 10?
Can't get any meaningful data from such a small sample (IMO).
Quote:
Originally Posted by Kevin Kirby
What is better, Davis, no data because no one took the time and effort to do even a small study, or a research study with only N=10?
Even research projects with large cohorts of N=200, can produce meaningless results if not designed properly. For this reason, I won't dismiss a study with only N=10, if the study was designed well and if the research studied a meaningful clinical question since I know how much time and effort is required to perform even a small study such as this..... it is much better than no data at all.
Quote:
Originally Posted by efuller
I wouldn't dismiss this study for the small N either, especially since it makes sense. I've always had a problem with the lift takes the tendon off stretch explanation because the tension in the tendon comes more from active contraction of the muscle rather than passive tension at the end of excrusion of the tendon.
I would never reflexively dismiss a study based on sample size. That is why we have effect size calculations. Doing a within subject comparison you can get away with smaller sample sizes than with between subject comparisons.
To blindly dismiss a n=small number study without looking at the nature of the design (within subjects vs between subjects); the effect size; and Eric's point of theoretical coherence is just as flawed as doing an unethical study by including more subjects than what is actually needed (which is why we have sample size calculations)
Sharons study was a n=3 and all subjects moved in the same direction....that has to be explained.
The Effects of Orthotic Heel Lifts on Achilles Tendon Force
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