Working in Movement

Exert yourself enough and you get tired; your muscles just don't want to do it anymore. Many marathon runners are familiar with this experience of "hitting the wall." The spirit is willing, but the flesh, the muscles, they just want to rest. Common wisdom has it that this muscular fatigue happens because the muscles run out of fuel or are overcome by an accumulation of lactic acid.

Ideas and research are emerging that challenge this widely held belief. And at least one movement educator was putting forth these new ideas as long ago as 1949.

Mind over Muscle or Where is Fatigue? points to a copy of Running on Empty, an article that first appeared on Newscientist.com in March. The article reports on the work of Timothy Noakes and collegues. Noakes basic idea is that the muscles themselves don't fatigue. The sensation of fatigue comes from the brain--they sense the muscles have had enough and send out the signal to cut back the effort. But, in fact, say Noakes, the muscles are capable of going on. They can be kind of tricked into getting used to this idea by interval training.

Noakes calls his theory the central governor. As the article from the New Scientist puts it:

The essence of their new theory is that the brain, using a mix of physiological, subconscious and conscious cues, paces the muscles to keep them well back from the brink of exhaustion. When the brain decides it's time to quit, it creates the distressing sensations we interpret as unbearable muscle fatigue. This "central governor" theory remains controversial, but it does explain many puzzling aspects of athletic performance, as well as suggesting some revolutionary approaches to training and offering tantalising hints as to the cause and maybe even the cure of chronic fatigue syndrome.

This can seem like real cutting edge stuff. But I remembered that I had read the basic ideas a few years ago. When I checked it out, I found that these sorts of ideas were put forth by Moshe Feldenkrais in his 1949 book Body and Mature Behavior.

In a living person, when a muscle is fatigued by voluntary contractions, application of electrical stimuli to the motor nerve or to the muscle itself results in powerful contractions. This shows that the fatigue is higher up in the system. In fact, the motor nerve cells responsible for the activation of the muscle are the weakest link in the circuit.

Thus, the motor nerve cell in the cortex, by failing to send the excitory stimulus, is the first cause of fatigue in muscles. The motor end plate is the next to fail. The nerve trunk is practically indefatigable. [Body and Mature Behavior, chapter 8, Fatigue]