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May 30, 2005
Is This Like Mind-Training on Steroids? If You Want to Get Stronger, Beef Up Your Mind-Muscle Connection.
A legend of the iron game, weightlifting champion Yuri Vlasov, quipped that judging a man's strength by his size was akin to judging a book by its thickness. It is not the beef but a superior ‘mind-muscle link’ that enables one hundred and sixty-five pounders to squat six or seven big ones. The following crash course in neuroscience of strength shall clarify that point.
A skeletal muscle consists of thousands of muscle fibers that generate force when they contract.
A group of fibers is hooked up to the brain through a nerve cell called a motor neuron. This group is referred to as a motor unit, or an MU.
A muscle fiber either contracts, or it does not; there is no intermediate 'half contracted' state. This is the all-or-none law. The nervous system varies the force output of an individual motor unit by its firing frequency. Like the cylinders of an internal combustion engine, muscle MUs do not fire constantly, but at intervals. Firing the fibers with a greater frequency increases the muscle's force and power output, just like increasing a car engine's number of revolutions per minute.
Firing synchronization with other motor units is another way your nervous system can vary the muscle's force output. Normally motor units take turns firing to produce a smooth, controlled movement. A good analogy is running. You push off with one leg at a time. The force production is half of what you are capable of, the movement is smooth, and while one leg is working, the other one gets a chance to rest.
Long-term heavy training synchronizes the MU activation. As a result, you become what Russians call 'an elephant in a glassware store' (forget them bulls and china, Comrade). Your movement becomes more forceful, jerky, and cannot be sustained for a long period of time, like broad jumping. Fine motor control goes south. Your wife does not let you close to the dishes, which is just as well.
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Posted by james at May 30, 2005 5:55 AM