Exploring the Links Between Human Movement, Biomechanics & Gait
Yay for the lift, spread and reach exercise!
Toe spreads and squeezes are aimed at strengthening specific intrinsic foot muscles—the dorsal and plantar interrosei, according to Irene S. Davis, PhD, PT, director of the Spaulding National Running Center and a professor in the Department of Physical Medicine and Rehabilitation at Harvard Medical School in Boston. Doming or foot shortening exercises contract most of the muscles on the plantar side of the foot, and help to strengthen the abductor hallucis muscle
A visual example of the consequences of a leg length discrepancy.
This patient has an anatomical (femoral) discrepancy between three and 5 mm. She has occasional lower back discomfort and also describes being very “aware” of her second and third metatarsals on the left foot during running.
You can clearly see the difference in where patterns on her flip-flops. Note how much more in varus wear on the left side compared to the right. This is most likely in compensation for an increased supination moment on that side. She is constantly trying to lengthen her left side by anteriorly rotated pelvis on that side and supinating her foot and trying to “short” the right side by rotating the pelvis posteriorly and pronating the foot.
With the pelvic rotation present described above (which is what we found in the exam) you can see how she has intermittent low back pain. Combine this with the fact that she runs a daycare and is extremely right-handed and you can see part of the problem.
Leg length discrepancies become clinically important when they resulting in a compensation pattern that no longer works for the patient. Be on the lookout for differences and wear patterns from side to side.
It is Rewind Friday. Today, we are reaching back to a brief 2009 lecture I did for the local NSCA chapter on the patterns of kinetic chain compensation that match with loss of medial and lateral foot tripod. (video starts at 49 seconds, for some reason) https://www.youtube.com/watch?v=yeCBGZkNaeM
5mm cut off ? MaybeYou are likely to come across hip and knee arthroplasty clients (total joint replacements). When they take a joint out and replace it with a new one, it can be a true challenge to restore leg lengths to equality side to side. Problems often arise down the road once gait is resumed and rehabilitation is completed. It can take time for the leg length discrepancy (LLD) to begin to create compensatory problems. This article seems to suggest that 5mm is the tipping point where gait changes becoming a problem are founded. Other sources will render different numbers, this article found 5mm. The authors found that both over- and underrestoration of leg length/offset showed similar effects on gait and that Gait analysis was able to assess restoration of biomechanics after hip replacement. I would chose to use the word “change” over restore, since the gait analysis is merely showing the deployed strategies and compensations, never the problem. But it is a tool, and gait analysis can be a decent tool to show “change”.*Remember, it is not always a product of true length, it can come from the pelvis posturing and/or from the acetabular orrientation, which can be a postoperative sequella. One cannot over look acetabular inclination, anteversion and femoral component anteversion/retroversion issues.Just remember, before you start making LLD changes with inserts, cork, orthotics etc be sure that you have restored as best as possible, pelvis-hip-spine mechanics because changes here can reflect as a mere leg length discrepancy. And it goes the other way as well, a LLD can cause those changes above.
* Just use your brain and don’t just lift the heel, give them a full sole lift. Heel lifts for this problem are newbie mistakes. Don’t be a newbie.
Below you will find an article on footwear and running. Rice et al concluded that
“ When running in a standard shoe, peak resultant and component instantaneous loadrates were similar between footstrike patterns. However, loadrates were lower when running in minimal shoes with a FFS (forefoot strike), compared with running in standard shoes with either foot strike. Therefore, it appears that footwear alters the loadrates during running, even with similar foot strike patterns.
They concluded that footwear alters the load rates during running. No brain surgery here. But that is not the point I want to discuss today. Foot strike matters. Shoes matter. And pairing the foot type and your strike patterns of mental choice, or out of natural choice, is critical. For example, you are not likely (hopefully) to choose a HOKA shoe if you are a forefoot striker. The problem is, novice runners are not likely to have a clue about this, especially if they are fashonistas about their reasoning behind shoe purchases. Most serious runners do not care about the look/color of the shoe. This is serious business to them and they know it is just a 2-3 months in the shoe, depending on their mileage. But, pairing the foot type, foot strike pattern and shoe anatomy is a bit of a science and an art. I will just mention our National Shoe Fit Certification program here if you want to get deeper into that science and art. (Beware, this is not a course for the feint of heart.)
However, I just wanted to approach a theoretical topic today, playing off of the “Forefoot strike” methodology mentioned in the article today. I see this often in my practice, I know Ivo does as well. The issue can be one of insufficient endurance and top end strength (top end ankle plantar flexion) of the posterior mechanism, the gastrocsoleus-achilles complex. If your calf complex starts to fatigue and you are forefoot striker, the heel will begin to drop, and sometimes abruptly right after forefoot load. The posterior compartment is a great spring loading mechanism and can be used effectively in many runners, the question is, if you fatigue your’s beyond what is safe and effective are you going to pay a price ? This heel drop can put a sudden unexpected and possibly excessive load into the posterior compartment and achilles. This act will move you into more relative dorsiflexion, this will also likely start abrupt loading the calf-achilles eccentrically. IF you have not trained this compartment for eccentric loads, your achilles may begin to call you out angrily. Can you control the heel decent sufficiently to use the stored energy efficiently and effectively? Or will you be a casualty? This drop if uncontrolled or excessive may also start to cause some heel counter slippage at the back of the shoe, friction is never a good thing between skin and shoe. This may cause some insertional tendonitis or achilles proper hypertrophy or adaptive thickening. This may cause some knee extension when the knee should not be extending. This may cause some pelvis drop, a lateral foot weight bear shift and supination tendencies, some patellofemoral compression, anterior meniscofemoral compression/impingement, altered arm swing etc. You catch my drift. Simply put, an endurance challenged posterior compartment, one that may not express its problem until the latter miles, is something to be aware of.
Imagine being a forefoot striker and 6 miles into a run your calf starts to fatigue. That forefoot strike now becomes a potential liability. We like, when possible, a mid foot strike. This avoids heel strike, avoids the problems above, and is still a highly effective running strike pattern. Think about this, if you are a forefoot striker and yet you still feel your heel touch down each step after the forefoot load, you may be experiencing some of the things I mentioned above on a low level. And, you momentarily moved backwards when you are trying to run forwards. Why not just make a subtle change towards mid foot strike, when that heel touches down after your forefoot strike, you are essentially there anyways. Think about it.
Shawn Allen, one of The Gait Guys
Footwear Matters: Influence of Footwear and Foot Strike on Loadrates During Running. Medicine & Science in Sports & Exercise: Rice, Hannah M.; Jamison, Steve T.; Davis, Irene S.
Another tool for you, in addition to making sure the gluten are on line, to improve ankle rocker and hip extension.
“This study concludes that neural mobilization techniques are a useful adjunct to static stretching, without any risk of adverse events or injuries. Athletes or trainers can consider using one or both types of neural mobilization techniques to enhance muscular flexibility. Dosage of the neural mobilization as well as the proposed working mechanism behind the increase in hamstring flexibility can be found in the full text of the article.”
Phys Ther Sport. 2016 Jan;17:30-7. doi: 10.1016/j.ptsp.2015.03.003. Epub 2015 Mar 17. Short term effectiveness of neural sliders and neural tensioners as an adjunct to static stretching of hamstrings on knee extension angle in healthy individuals: A randomized controlled trial. Sharma S, Balthillaya G2, Rao R, Mani R .
You’re either part of the solution or part of the problem. Read and you decide if this kind of advice is actually helping people. We know what we think.
After all, everyone should fit the same mold right? And, altering what you are doing fixes the problem right? It must finally be time for Ivo and I to retire. Someone just build the DIY App for 2.99 and make all the running problems in the world go away. After all, truly “FIXING foot strike is relatively simple”. Clearly Ivo and I just enjoy making things terribly complex because we have nothing better to do. To be fair to this author, There is a reason why we stopped writing for venues, because everything got so cooked down by the editorial staff until our stuff said nothing , or worse yet, simplified things so much that a monkey could do it, that we said, “ thanks, but we will take a pass on the next one”. Oy vey. Feeling saucy tonight. Reader beware.
More on landing mechanics. Here is a recent article on landing mechanics. This article talks about the landing mechanics far past where I feel the first stage of vulnerability is, which is initial forefoot load, as i discuss in the video pertaining to landing from a jump or if sprinting (forefoot loading). IF landing occurs in low gear (lateral half of the forefoot), inversion risks are higher. The medial foot tripod, high gear toe off (1st and 2nd mets) is where we should be taking off from, and landing initially upon. Anything lateral is vulnerable without the lateral column strength (lateral gastrocsoleus complex, peronei longus/brevis). This article talks about knee flexion angles and ACL vulnerability, far after this initial loading response. The article some valid conclusions in that phase.
One point and 1 treatment can profoundly influence gait
When talking about the lower extremity and gait (as I have been know to do at more that one seminar), I often talk about the “reverse engineering” principle. This is looking at a muscle or muscle group from a “ground up” perspective, as it would be functioning during the gait cycle. This, along with knowing when a muscle should be firing in the gait cycle, can provide clues to what may be going on and how you may be able to help.
When discussing the quads, we often employ this principle. It can be a little difficult to think of the vastus medialis as a lateral rotator of the thigh and the rectus femoris as a flexor (anterior nutator) of the pelvis, but if you put your foot on the ground and think about it, you will see what I mean.
The VMO is often implicated in patello femoral syndromes but cannot be selectively activated. The ratio between vastus medialis and vastus lateralis does seem to be alterable and perhaps is a siginificant factor.
How about if we look at the vastus lateralis instead?
The vastus lateralis is the largest and most powerful portion of the quadriceps. One paper reports that the muscle volume of the the vastus lateralis was 674 cm3 followed by the vastus intermedius at 580 cm3, vastus medialis 461 cm3 and lowest in the rectus femoris 339 cm3. This makes the vastus lateralis is twice the volume of the rectus femoris!
Studies of muscle fiber orientation show that VL force component is directed approximately 12-15° laterally with respect to the longitudinal axis of the femoral shaft. This would mean it has a tremendous mechanical advantage and could (should?) pull the patella directly laterally compared to the VMO force, whose component is directed approximately 55 ° medially. The muscle “balance” between the VMO and the VL, along with the periarticular soft tissue structures acting on the patella, is considered major component in the control of normal patellar alignment and function. The VL is often considered to be the “overactive” one by many clinicians, particularly in cases of patellofemoral dysfunction. It turns out that from an EMG standpoint, they may be correct.
The vastus lateralis arises posteriorly from the femur along the linea aspera and circumnavigates the thigh in a counterclockwise fashion to attach laterally to the patellar tendon. Because of its size and fiber orientation, it would stand to reason that needling it would have more cortical representation than say the vastus medialis.
There is an interesting paper where they needled a single acupuncture point: Stomach 34. For those who haven’t studied acupuncture (or don’t remember) this point is located on the thigh, in a small depression about 2.5 inches (63 mm for the metric folks) lateral to and above lateral border of the patella. In other words, it is in the vastus lateralis (see above).
The results showed statistically significant improvement in velocity, cadence, stride length, cycle time, step time and single/double leg support after treatment. The effect was small, but positive.
Think about where the trigger points are for this muscle (see above) ; fairly close to this point, sometimes (depending on the trigger point), even directly over this point. Needling has many effects on muscle and its trigger points and we like to think that needling “normalizes” function of a muscle; perhaps it influences the apparent “dominance” of this muscle and allows the patella to track more medially?
So, in this popultion of patients of elderly individuals, 1 acupuncture (needling) treatment had a positive influence on their gait. Perhaps if the folks in the knee study were treated a few more times, we would have seen a change. Imagine what could have happened if aditional treatment modalities, like exercise, proprioceptive work and gait retraining were added!
What a great, cost effective alternative or addition to your rehabilitation this could be. Consider adding this modality (and point!) to your current clinical toolbox, not only for older patients but for any patients that may have a gait abnormality.
Kim, H. H., & Song, C. H. (2010). Effects of knee and foot position on EMGactivity and ratio of the vastus medialis oblique and vastus lateralis during squatexercise. Journal of Muscle and Joint Health, 17(2), 142-150.
Lam, P. L., & Ng, G. Y. (2001). Activation of the quadriceps muscle during semisquatting with different hip and knee positions in patients with anterior knee pain. American Journal of Physical Medicine & Rehabilitation, 80(11), 804-808.
Erskine, R. M., Jones, D. A., Maganaris, C. N., & Degens, H. (2009). In vivo specific tension of the human quadriceps muscle. European journal of applied physiology, 106(6), 827-838. [PubMed]
Grabiner MD: Current Issues in Biomechanics (9th ed). Champaign, Human Kinetics Publishers, 1993.