Exploring the Links Between Human Movement, Biomechanics & Gait
Salsa Dancing for Age related Functional Deficits.
Don’t dismiss it until you have tried it. For 3 years we did it here at The Gait Guys (and salsa was one of our favorites), so we know what it is all about … . the foot work, the amount of core stability needed, hip stability, lower abdominal skills, balance, proprio, vestibular accommodation etc. Dancing is no joke, and no you are not too cool to do it. Here in America we are the exception, not the rule. In most countries, after dinner, they push the tables to the sides and people dance the night away. In many countries, men dance. Looking to impress guys? Take some lessons. Looking to get your elderly clients active, set them up with your local dance studio and improve their health.
– random thoughts from Dr. Allen
Their study’s conclusions: “Salsa proved to be a safe and feasible exercise programme for older adults accompanied with a high adherence rate. Age-related deficits in measures of static and particularly dynamic postural control can be mitigated by salsa dancing in older adults. High physical activity and fitness/mobility levels of our participants could be responsible for the nonsignificant findings in gait variability and leg extensor power.” – Granacher et al. http://www.ncbi.nlm.nih.gov/pubmed/22236951
Evaluating the Differential Electrophysiological Effects of the Focal Vibrator on the Tendon and Muscle Belly in Healthy People ARTICLE in ANNALS OF REHABILITATION MEDICINE · AUGUST 2014 DOI: 10.5535/arm.2014.38.4.494 · Source: PubMed
J Neurophysiol. 2014 Jul 15;112(2):374-83. doi: 10.1152/jn.00138.2014. Epub 2014 Apr 30. A neuromechanical strategy for mediolateral foot placement in walking humans. Rankin BL
J Neurophysiol. 2015 Oct;114(4):2220-9. doi: 10.1152/jn.00551.2015. Epub 2015 Aug 19.
Hip proprioceptive feedback influences the control of mediolateral stability during human walking.
Roden-Reynolds DC1, Walker MH1, Wasserman CR1, Dean JC2.
Eur Spine J. 2015 May 26. [Epub ahead of print] Prevalence of gluteus medius weakness in people with chronic low back pain compared to healthy controls. Cooper NA1, Scavo KM, Strickland KJ, Tipayamongkol N, Nicholson JD, Bewyer DC, Sluka KA.
Prog Brain Res. 2004;143:353-66. Role of the cerebellum in the control and adaptation of gait in health and disease. Thach WT1, Bastian AJ.
You’d have to be smart to walk this lazy, and people are
Research suggests that humans are wired for laziness
Proprioceptive afferent inputs can control the timing and pattern of locomotion. When disease is present, or when injury has compromised the neuro-biomechanical linkages, slow postural responses can trump what timely responses are necessary to ensure for smooth locomotion.
When many people think of balance and locomotion, the cerebellum is often a top topic for it is important for movement control and plays a particularly crucial role. Thus, a most characteristic sign of cerebellar damage is walking ataxia. It is not known how the cerebellum normally contributes to walking, although recent work suggests that it plays a role in the generation of appropriate patterns of limb movements, dynamic regulation of balance, and adaptation of posture and locomotion through practice. (1)
Reflex pathways exist which regulate the timing of the transition from stance to swing, and control the magnitude of ongoing motoneuronal activity. During locomotion there is a closely regulated feedback from the various sensory receptors in the skin, joints, muscles, tendons, ligaments and other tissues, this is referred to as afferent feedback. When there is damage to these sensory “organs”, or the pathways into, or out of, the central nervous system locomotion becomes difficult. We can see this in the video case above. This is a case of Chronic Inflammatory Demyelinating Polyradiculopathy (CIDP). It is an immunne-mediated inflammatory disorder of the peripheral nervous system whereby the myelin sheath of neurons is slowly eroded and as a result, the affected nerves and pathways fail to respond well rendering numbness, paresthesias, pain and progressive muscle weakness along with loss of deep tendon refexes. Obviously this will render locomotion fatiguing and difficult. Falls are not uncommon as you can see in the video.
Timing and coordination is everything in gait. When a portion of the system is compromised from injury or neurologic deficit, locomotion becomes strained. There is an intricate balance between the extensor and flexor muscles. We found this quote by Lam and Pearson particularly relevant to today’s discussion and video.
“Proprioceptive feedback from extensor muscles during the stance phase ensures that the leg does not go into swing when loaded and that the magnitude of extensor activity is adequate for support. Proprioceptive feedback from flexor muscles towards the end of the stance phase facilitates the initiation of the swing phase of walking. Evidence that muscle afferent feedback also contributes to the magnitude and duration of flexor activity during the swing phase has been demonstrated recently. The regulation of the magnitude and duration of extensor and flexor activity during locomotion is mediated by monosynaptic, disynaptic, and polysynaptic muscle afferent pathways in the spinal cord. In addition to allowing for rapid adaptation in motor output during walking, afferent feedback from muscle proprioceptors is also involved in longer-term adaptations in response to changes in the biomechanical or neuromuscular properties of the walking system.” (2)
Gait and any form of locomotion are highly complicated with many pieces necessary to achieve clean, smooth, coordinated motion. Failure in only one piece of the puzzle can result in profound unhinging of the entire system because of the entangled nature of the feedback loops.
Nothing dramatic today gang, just some thoughts that came to us after seeing this client and doing some reading to keep up on things. We thought this would be a nice follow up to Monday’ blog post on proprioception.
As I sit here on a rare Friday afternoon, not working (OK, I am writing this, so sort of working) and looking out at the lake (picture above), while on a family camping trip, I think about a walk on the rocks this morning with my kids. I was watching my very skilled 7 year old jump from rock to rock while my 3 1/2 year old, that thinks he is seven, tried to follow his older brother.
I had my foot on a rock which lowered the front of my foot in plantar flexion and stood on that leg. I noticed that my balance was not as great as it was when my foot was in dorsiflexion. This made me think about pronation and supination. Yes, it is not uncommon for me to think about such things, especially when I have some spare time. That is one of the things about being a foot and gait nerd; these sorts of things are always on our minds.
So, why was my balance off? Did I need more proprioceptive work? Were my foot intrinsics having issues? No, it was something much more mundane.
Pronation consists of dorsiflexion, eversion and abduction. This places the foot in a “mobile adaptor” posture, reminiscent of our hunter/gatherer ancestors, who needed to adapt to uneven surfaces while walking over terra firma barefoot. Supination, on the other hand (which is the position my foot was in), consists of plantarflexion, inversion and adduction. It places the foot (particularly the midtarsals) in a locked position for propulsion (think of the foot position during toe off).
So why when my foot was plantar flexed and adducted while standing on this rock so much more unstable in this supposedly more stable, supinated position? I would encourage you, at this point, to try this so you can see what I mean. When I placed my foot in dorsiflexion on the rock, I was much more stable. A most interesting conundrum for a biomechanist.
Experimenting for a few minutes, alternating plantar flexion and dorsi flexion, gave me the answer. When we are walking on the flats, our foot is (usually) not pushed to the extremes of dorsiflexion; with the front of the foot up on a rock, it is much more so. This “extra” upward force on the front of the foot, provides much more sensory input (and thus proprioception) from the ball of the feet. Take a look at the sensory homunculus and you can see how much brain real estate is dedicated to your foot, especially the front portion. With this information, we are able to apply more force through the posterior compartment of the leg,which is stronger than my anterior compartment (as it is with most folks).
When the front of your foot is in plantar flexion (ie, your heel is on the rock), we have less sensory input to the balls of the feet, and rely more on the anterior compartment (weaker in many folks, including myself) to counterbalance the weight of our body.
Mystery solved: proprioception trumps biomechanics; more proof that the brain is smarter than we are.
The Gait Guys. Solving the worlds great gait questions, one at a time.
The 5 Point Turn (in a human). Do you know this gait problem ?
Here is a video link for the full video case study with diagnosis and more details on this client’s gait but our point here today is to look at the uniquely pathologic turning motor pattern deployed by this patient.
Gait analysis is so much more than watching someone move on a treadmill. Forward momentum at a normal speed can blur out many of a person’s gait pathologies. We discussed this in detail in this blog post on slowing things down with the “3 second gait challenge”. Furthermore, most gait analysis assessments do not start seated, then watching the client progress to standing, and then initiating movement. Watching these intervals can show things that simple “gait analysis” will not. Finding stability over one’s feet and then initiating forward motion can be a problem for many. Those first moments after attaining the standing position afford momentum to carry the person sideways just as easily as carrying them forward. In other words, once momentum forward begins, a normal paced gait can make it difficult to see frontal plane deficits. Our point here, transitional movements can show clues to gait problems and turning to change direction is no different.
Typically when we turn we use a classic “plant and pivot” strategy. We step forward on a foot (right foot for example here), transfer a majority load on that forward right foot, we then pivot the left foot in the next anticipated direction of movement, and then push off the right foot directionally while spinning our body mass onto that left foot before initiating the right limb swing through to continue in the new direction.This is not what this patient does. Go ahead, stand up and feel these transitions, if you are healthy and normal they are subconscious weight bearing transitions but for some one who is old and losing strength and proprioception/balance or some one with neurologic decline for one reason or another, these directional changes can be extremely difficult as you see in this video here. A full 180 degree progression is often the most difficult when things get really bad. And more so, if one leg is more compromised than the other, turning one way a quarter turn (a 90 degree directional change) might be met with an alternative 270 degree multiple-point turn in the opposite direction over the more trusted limb to get to the same directional change. When there is posterior column disease or damage this seemingly simple “plant/weight shift/ pivot and push off” cannot be trusted. So a 5 point (or more) turn is deployed to be sure that small choppy steps maximize minimal loss of feel and maximal ground contact feel. This can be seen clearly in this video above.
Just some more things to think about in your gait education. Watch your clients move from sit to stand, from stand to initiating gait, and then watch closely their turning strategies. At the very least, have them make several passes making their about-face turns both to the right and the left. You will often see a difference. Watch for unsteadiness, arm swing changes, cross over steps, reaching for stability (walls, furniture etc), moving of the arms into abduction for a ballast effect and the like. Then correlate your examination findings to your gait analysis. Then, intervene with treatment and rehab, and review their gait again. Remember, explaining their deficiencies is a huge part of the learning process. Make them aware of their 5 point turns, troubles pivoting to the right or the left, and make them understand why they are doing the goofy one-sided rehab exercises. Understanding what is wrong is a huge part of fixing your client’s problems.
* Remember: if your client is having troubles on a stable surface (ie. the ground) then they should engage some rehab challenges on the ground. Giving them a tilt board or bosu or foam pad (ie. making the ground more unstable) will make things near impossible. This is not a logical progression, we like to say, “if you can’t juggle one chainsaw we won’t give you 3”. Improve their function on a stable surface first, then once improvements are seen, then progress them to unstable surfaces.