If one tried to curl a bar bell with, say, 1000 pounds of weight, ten times at a session every other day for a month, one would never manage to lift it.  However, each trial would stress the biceps.  As such, even though the muscle never succeeded in lifting that extreme weight it would become stronger.  Similarly, if one tightened his biceps and his triceps at the same time his arm would become very rigid, but it wouldn’t move.  However, the muscles would become stronger from being stressed in opposition to each other. 

Now, I don’t know the names of the little finger muscles that cause it to straighten and to curl, however, if one is aware of wanting to stress one of them but doesn’t want to move his finger, it is likely that both the opposing muscles will respond.  As such, they are both being exercised and will be getting stronger.  I propose that this is likely to happen when a person thinks about flexing his little finger.

Occam

I see, Occam. The problem is that a gain in strength by 22%! really seems like a lot; I would understand 0.22% (I think).

I don’t mind making “other” plans and it doesn’t really bother me getting to an end of a route and realizing that I haven’t noticed my surroundings. Maybe I am being na‘ve but I have always felt that I am pretty much in control of my life, even though I am always making “other plans”, worrying, or fantasizing; I like it that way. Perhaps I don’t understand how meditation works because I don’t understand WHY it should work to begin with.

If it ain’t broke, don’t fix it   If you don’t need what meditation might get you, there’s no reason to do it. And I’m certainly not in the camp of telling other people that they’re not “really” happy if they say they are. For me, it’s reduced my level of frustration and dissatisfaction a bit, though exercise and a walk in the woods work pretty well for me too.

As for the imagined movement and effects on muscles, I’ve found lots of intriguing but still pretty vague and preliminary research. Can’t say if there’s any truth to it. Occam’s idea that it is a form of isometric exercise is interesting. The link below starts with the abstract from the study you referred to in your original post, and links to a number of related studies on imagined movement. I guess one spur to this research is the idea of mapping the nerual activity that is generated by imagining movements and then reading that with some device which could then activate a mechanical prosthesis or something, thus giving people with spinal cord injuries some mechanism of affecting the outside world through “thoughts.” It makes sense that, since as a materialist I believe all mental activity is ultimately electrical/chemical activity in the brain, that the right understanding and tools could enable us to “decode” the neural activity. This idea makes a lot of assumptions about how subjective experiences are encoded in neural activity, and these may not turn out to be true, so I don’t know how far we might eventually go in this direction, but it is intriguing. And if we could succeed, it would be close to the ultimate disproof of dualism, as a bonus.

:oops:  Oh, yeah, the link….

http://jn.physiology.org/cgi/content/abstract/67/5/1114?ijkey=8c9773fac45bbec372a8b616f1e60973db8fa6c6&keytype2=tf_ipsecsha

Interesting abstract, Brennen. And it sounds like they accept something like the explanation I was giving before:

[quote author=“G. Yue and K.J. Cole”]Strength increases can be achieved without repeated muscle activation. These force gains appear to result from practice effects on central motor programming/planning.

“Central motor programming/planning” has to mean some neural effect, in the brain. I expect that this is simply a hypothesis on their part (“appear to result”), but without looking at the body of their paper it’s impossible to tell.

[quote author=“George Benedik”]I see, Occam. The problem is that a gain in strength by 22%! really seems like a lot; I would understand 0.22% (I think).

Funny, I thought 22% was pretty small.  If one could lift, say, five pounds with one’s little finger before exercising, lifting six pounds, two ounces afterwards doesn’t seem at at all unexpected.

Occam

[quote author=“G. Yue and K.J. Cole”]Strength increases can be achieved without repeated muscle activation. These force gains appear to result from practice effects on central motor programming/planning.

Does this mean that it appears that it is in reality not the finger that gains the strength but rather the part of the brain that is responsible for the finger’s activity? In other words: we are training the brain, not the actual finger (?).

Yes, we are essentially training the brain rather than the muscle. There is no “muscle hypertrophy,” meaning growth in the actual msucle. When the experimenters electrically stimulated the ulnar nerve, that controls the relevant muscles, so that it was maximally stimulated, there greatest strength possible for the muscle was the same before and after training. What was different was the force the muscles could exert when moved voluntarily.

I suspect part of what happens involves the phenomenon of recruitment of motor units. Muscle contain many functional subunits, called motor units, and not all of the are activated every time the muscle is used. Otherwise, muscles would only have two states-inactive and maximally active. The reason we are able to exert force along a gradient from most gentle to strongest movement is because we can voluntarily control the number of functional subunits we activate during a given movement. Possibly, imagining the movement strengthens the connection between nerve and muscles (increasing neurotransmitter release, or post-synaptic receptors, or the number of nerve fibers present, etc), and this allows more motor units to be voluntarily engaged. I’m guessing as far as the mechanism based on general principles of how skeletal muscle works. The important point is that there is actually a lot of subtlety to how voluntary movement is initiated and controlled, involving multiple areas of the brain, spinal cord, peripheral nerves, and muscles. Imagined movements focus on the signalling components (nerves) rather than the actual force transducer (muscle), but this is still a reasonable way to affect the amount of force one can ultimately generate since much more than just the muscle is involved in the process.

Thank you, Brennen. It now makes sense to me.

I now also realize that Doug answered he problem correctly when he said that:

Perhaps that 22% is simply in the nerves’ influence on muscles.

Perhaps I need to meditate after all. :wink:

So, it looks like my theory is one of several out there, but the exact mechanism has not been elucidated yet.

from PHYS THER
Vol. 85, No. 10, October 2005, pp. 1053-1060
Can Mental Practice Increase Ankle Dorsiflexor Torque?
Ben Sidaway and Amy (Robinson) Trzaska

“Possible mechanisms of these neural adaptations include the extent of motor unit activation, improved coordination, and decreased co-contraction of antagonist muscles.”

Apparently, the number of motor units one can activate with maximal effort is related to the size of the area of the brain in which the muscle involved is represented. In muscles which have large cortical representation (e.g. fine motor muscles of the hand) it is possible to stimulate most or all motor units with maximal voluntary effort. However, is muscles less well-represented (such as thoses for extending the ankle), maximal force cannot be voluntarily generated. Howevere, training (actual or imaginary) seems to increase the area of the cortex devoted to controlling the muscle, which then increases the strength one can generate. But, as the quote above indicates, there are other theories.

As far as the relative effect of muscle vs nerve/brain on muscle strength, an interesting study involved artificially imobilizing a limb for 4 weeks and determining the relative effects of neurological and muscle changes on the loss of strength. the conclusion was:

“These findings suggest that unweighting induces plastic changes in neural function that appear to be spatially distributed throughout the nervous system. In terms of the relative contribution of neural and muscular factors regulating strength loss, we observed that neural factors (primarily deficits in central activation) explained 48% of the variability in strength loss, whereas muscular factors (primarily sarcolemma function) explained 39% of the variability. “

J Appl Physiol 101: 264-272, 2006. Adaptations in human neuromuscular function following prolonged unweighting: II. Neurological properties and motor imagery efficacy
Brian C. Clark,1 Todd M. Manini,1 Stanley J. Bolanowski,2, and Lori L. Ploutz-Snyder1

Several studies have also looked at the effect of imaginary activity or imaginary suppression of activity in various muscles on the neural input to these muscles and have found, generally, a significant effect. You can increase or decrease brain and spinal cord activity relevant to a specific movement by imagining doing or supressing the movement. Cool!

Clearly, the brain (and the mind, which of course are essentially the same thing) has a powerful role in determining what the body does, and it is possible to imagine such things as increasing muscle strength by thinking about moving the muscle without any mystical mumbo-jumbo. And, of course actual use of the muscle shows even greater effects in all the studies even before enough time has passed for true muscle changes to occur. This is interesting theoretically, but it obviously has some implications for people with deficits in the relationship between mind and body. Some of the changes with imagined movement we’ve been talking about turn out not to happen in an organized, reliable way in patients with Parkinson’s Disease, for example. So maybe ” meditation” (defined quite loosely) would help these patients. But maybe you’d be better off just lifting weights :wink:

Sorry if this is too much info. Sort of in my field, so I get carried away.

Interesting results, Brennen. I am sure a lot more experimentation will have to be done before we even can be sure these effects are real, much less determine how they work. It will also be necessary to see (if they work) what the limits are. What sorts of physical end-points can be achieved by the equivalent of guided imagery, and what sorts can’t?