Neuromuscular Control - Science topic

Hi Fakhruddin,

I'm not sure if I follow you exactly, but I will at least attempt to provide some level of feedback. There are several locomotor control theories that provide additional perspective on how the integrated effects of the nervous system and musculoskeletal systems interact to control movement. For example, Sparrow and Newell (Psychonomic Bulletin & Review, 1998, 5 (2), 173-196) proposed a metabolic energy expenditure component to regulating movement. In my work with individuals with a spinal cord injury we used an extension of their theory, and the fact that walking may be an emergent phenomenon (co-authors went on to publish a good review on this: Gollie, Guccione, Overground locomotor training in spinal cord injury: A performance-based framework). I would suggest trying to be more specific with your question, especially if you're asking something mechanistic in nature. I hope this helps.

If your aim is to look specifically at muscle firing patterns then EMG may be your best bet. If your goal is to see if the neuromuscular training program results in learning, you may want to use frontal lobe fNIRS (activity decreases as the movement is learned) or you can simply look at performance curves and retention tests.

Dear Gregory S Cantrell

perhaps the (partly older) literature can help - at least to avoid to reinvent the wheel:

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Cortical and spinal excitability in patients with multiple sclerosis and

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4: Sosnoff JJ, Motl RW. Effect of acute unloaded arm versus leg cycling exercise

on the soleus H-reflex in adults with multiple sclerosis. Neurosci Lett. 2010 Aug

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5: Motl RW, Snook EM, Hinkle ML, McAuley E. Effect of acute leg cycling on the

soleus H-reflex and modified Ashworth scale scores in individuals with multiple

sclerosis. Neurosci Lett. 2006 Oct 9;406(3):289-92. PubMed PMID: 16916583.

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I want to measure physical fitness in cp, one of the component of health related physical fitness is flexibility. Brockport tests suggest sit and reach test, but in GMFCS III-IV, this test is not applicable.

Hello Bhaskar

Of course you can use copper, as every conducting material, to record surface EMG. To my experience copper has many disadvantages for that purpose. It will fast be covered by a patina (not only at the soldering points as mentioned by Joachim). This oxide (hydroxide) is caused by contact with salt water, sweat, soldering flux, conducting gel, or other agents which react with copper. The patina alters the electrode-skin impedance in an erratic fashion and this might influence the signals intended to record. That is why most electrodes are built (or at least covered) of precious metals or stainless steel. Using the latter for special purpose electrodes was always without problems in our applications. As Joachim already mentioned a kind of conducting gel or would be needed too. Please keep in mind, that pairing copper with other conducting materials might result in a bias voltage (cause by the electro-chemical voltage) which might drive your amplifier in saturation if you use a DC amplifier.

Try to use standard material first (e.g. your mentioned electrode, or a stainless steel plate of one dime in diameter) with your recording apparatus to be sure it is the copper material problem which let your records fail. What kind of recording system, which type of recording amplifier (differential, single ended, AC) are you using? In your description the purpose or practical reason why you persist to use copper is unclear. Maybe some explanations are possible without uncovering the secret application ;-).

Microelectrodes (I guess you are talking about electrodes of sizes < 1mm) will cause additional problems, of which the dramatically reduced recording area - i.e. the distance in space within any active muscle fibers must be situated to substantially contribute to the recorded EMG Amplitude – is the most influential. In short: small electrodes monitor only few muscle fibers, and those might eventually not be representative for the activity of the whole muscle.

Regards Thomas

Thanks

If you're looking for something a little more specific to the topic, here are two I refer to quite a bit:

The skeletal muscle book is great for the PNS, and covers the motor neuron (or motor unit) control of muscle quite well.  However, it doesn't cover the CNS much at all.  The first book, by Latash, is a good mix of both.

Hi,

I have been riding street and dirt motorcycles for 50 years and continue to do so. Dehydration is a major cause at attention deficit and slower reflexes among motorcyclists. Reflexes for motorcycle riding, like with many sports, depend on multiple coordinated events for recovering from an unintended slide, braking/clutch coordination, etc. So while typical proprioceptive off-balance training can be useful, specific drills on a motorcycle will likely offer the greatest yield.

Different motorcycles behave very different and the training should be machine-specific. Recovering a slide on my Honda Gold Wing or Victory Hammer is very different that recovering from an unintended slide on my KTM 520.

Ed 

Hamstring and quadriceps force, ratio, and rate of development are interesting, but to date have only been found to play a role in female athletes for prevention of ACL injury. At least that I'm aware of in the literature.

Currently, I think the best predictors are still hop tests, effusion, and global rating score for a quick in clinic assessment. However, return to sport must be done on a person by person basis depending on the individuals goals and likelihood for re-injury (graft type, age, body mass, are good predictors).

Tibial plateau geometry is interesting, but I have never had a patient that was interested in changing their bone shape to either avoid initial or secondary ACL injury. Therefore, this as a risk factor for possible interventions does not appear to be fruitful at this point.

Thoughts?

Certainly, one could use geometric principles to estimate an index of architecture from those parameters -- ultimately, the index of architecture takes advantage of those same geometric principles anyhow. RD Woittiez actually described the determination and use of the index of architecture in a pair of papers from 1983 and 1984. The 1984 paper (in the Journal of Morphology) has some illustrations that might help you conceptualize it all.

Depending on the muscle(s) that you are modelling, you could also look up architecture papers in the literature that report things like fascicle and muscle belly lengths, and compute your own ia -- some papers even report values of ia for the various muscles studied.

Of course, there are also other normalized mathematical representations of the force-length relationship for which you could implement your "length at maximum isometric force" parameter to specify the relationship for a specific muscle(s).

dynamic seating systems for children with cerebral palsy is seen to improve components of balance and tone with regards to short term changes. stating that it holds true in the long term is controversial since there are many accompanying therapy practices that are included in the rehab of the children. It is safe to say though that it does help improve cognition and orientation to the environment in the long term.