The Muscles are an Endocrine Gland
There’s a growing body of evidence that exercise has a direct influence on the brain. We’re not talking about the WOD brain we experience when our muscle and blood glucose is depleted, but more that good feeling of being more awake after exercise.
There is evidence that exercise reduces the depression. That it can mitigate the causes of obesity, not just through weight loss but through the excretion of a number “factors”—hormones, growth factors, and small proteins called cytokines that are important in cell signaling— into the blood stream by the working muscles. These secretions, they have complicated names, actually lead to structural and functional changes in the brain. These finding are leading many researchers to conclude that muscular system is endocrine gland.
Our structural muscles are made up of three types of muscle fibers: Type I, Type II and Type IIa. Type I is known as “slow twitch”, these fibers are the ones we use the majority of the time, they are the ones we use for low intensity exercise like walking, running and daily life. They’re Aerobic in that their energy comes from a process that requires oxygen. These fibers will be fueled as long as there is oxygen available, so most of the time. Long slow work is their domain.
Type II and IIa are known as “fast twitch”, these the fibers we use for movements that are intense or powerful; saving ourselves from a fall on ice, chasing our kids… There Anaerobic in that their energy comes from a process that does not require oxygen. These fibers have a short work span—think sprint not marathon—depending on how much energy they’ve stored before the required work.
We are born with all of our muscle cells (cells and fibers are the same thing). We don’t “create” more muscle when we exercise we just turn on more cells. As we age, if we don’t do work or exercise that requires the Type II, IIa fibers they will atrophy. They don’t die, we just stop using them and forget how to access them and they will return with proper exercise.
Weight Lifting works to turn around muscle atrophy, since it’s this type of exercise that works these fibers. If you can sprint rather than walk you can re-build these fibers. If sprinting is out of the question due to structural issues like bad knees you get the same results on a rower, a bike, any device where you can generate power. Think High Intensity.
Another benefit of lifting weights is an increase in bone density. There is a direct correlation between Type II fiber loss and Osteopenia weighting can be considered Structural Medicine.
CrossFit is a High Intensity training that uses functional/structural exercise to achieve a high power output. An easy way to increase exercise intensity is to include weight lifting, through either bar bells, dumb bells or kettle bells.