Why do we need to exercise? Why can’t we just lie on the couch? No, seriously - why not? By Dr. Murray McDonald
So let's consider the extreme: what happens when the body is immobilized and/or unloaded? Exhibit A: Bed rest. If our bodies are completely still a few things happen: fluid starts to pool in the face, chest, and other areas; our blood starts clotting; muscle starts to stiffen and weaken; we may become constipated; our kidneys become taxed; our bones start to demineralise.
Take it even further - literally into space - and we get a good idea of the benefits of movement.
Exhibit B: Prolonged microgravity / lack of movement causes bones and muscles to weaken, your heart rhythm to become dysfunctional, your blood pressure to rise, your balance and coordination to diminish, you to become anaemic, and also immunodeficient. Being an astronaut sounds great, right?
It seems our body need movement simply to function - without it everything starts to fall apart.
Let’s contrast that with the known benefits of exercise: muscles become stronger and more resistant to fatigue, bones get more resistant to fracture, your body gets better at using fat for energy, heart and lungs get more capable of and efficient at getting you oxygen, your blood pressure reduces, your blood cells increase, your hormones (including the sex ones) & immune cells function better, your digestion improves, and your brain function increases.
So basically everything gets better. But why?
This is because movement (coupled with gravity) produces force on our muscle & bone systems which gives them the signal to stay strong. Movement also causes a pumping effect through our veins which improves circulation and provides novel information to our nerves which have to sharpen their skills to keep up. The energy requirements of exercise stimulate our bodies to become more efficient at extracting it (from digestion / breathing) and using it (cell wall transport / enzyme function / hormone ratios).
Our bodies achieve this through a process of SUPERCOMPENSATION: exercise by its very definition is challenging - our bodies meet this challenge as best it can, but then in the ‘recovery period’ afterwards rebuilds things bigger and better. Your body likes to plan ahead should you ever again be attacked by an elliptical trainer.
Why is this very awesome? Because astronauts think they’re so cool with their jumpsuits and their “International Space Stations”. But while they’re up there getting tired, smaller muscles, weaker hearts, constipation, rubbish immune systems, anaemic, and uncoordinated, you’ll be on terra getting firmer, becoming bigger, stronger, faster. WHO’S COOL NOW, HUH?!
But maybe order a jumpsuit and some aviators just in case.