As part of my ongoing effort to exercise more regularly, I joined my daughter when she signed up for a beginner’s fencing class – and found myself the only parent in a class of 12 to 16 year olds. I expected that the younger students would have an advantage over me in our bouts – they were all in much better shape and didn’t tire out nearly as fast as I did – but most of the time I scored as many if not more touches as they did. An article that appeared online this month in the journal Neurobiology of Aging suggests one reason why. Unfortunately it also suggests that, for me, it’s all downhill from here.
The study, led by Dr. George Bartzokis at the Semel Institute for Neuroscience and Human Behavior at UCLA assessed how the speed of motor processing corellates with the integrity of the myelin sheaths covering neurons in the brain. They found that the two are correlated – neurons covered in myelin transmit nerve impulses faster, so brains that contain more myelin are also faster processors. But they also found that myelin integrity isn’t a static thing: as people age, more and more neurons in the brain get covered with myelin, speeding up cognitive and motor processing speed, eventually reaching a peak at age 39. After that, myelin starts to break down faster than it’s repaired, slowing down the transmission of impulses from brain to muscles. Guess how old I am?
So right now, the lag time between my *decisions* to parry, disengage, and riposte and my clumsy attempts to carry the actions out occur faster (on average) than my classmates’. But I’m poised at the crest of a long downhill slide. Eventually, my daughter is going to beat me every time.