When there is a problem, that signal could come from the gut or respiratory system but exercise can trigger a similar response, sending immune cells out on surveillance. If you go for a run there’ll be more immune cells in your blood, she says.
“It makes sense from an evolutionary point of view. If you were a cave man who broke into a run there’s a good chance you were hunting or fleeing from danger and at risk of an injury and an activated immune system would prepare for it.”
A healthy muscle mass can also help protect against the chronic diseases that can kick in with age.
“Muscles release molecules that over time help reduce the low level inflammation linked to so many chronic diseases. The more we exercise and the more intensely we exercise, the more we produce these molecules,” she says.
Regular exercise lowers the risk of some cancers and one reason may be because it maintains the quality of our muscle, keeping it lean. Physical inactivity, however, reduces its quality by increasing fat in the muscle, explains Rob Newton, professor of Exercise Medicine at Edith Cowan University.
“There are good studies showing that survival from a range of cancers is associated with the quality of a person’s muscle as well as its quantity. The mechanism is most likely the critical role of muscle in maintaining the effectiveness of the immune system,” he says.
“Exercise is also important for surviving cancer’s debilitating effects. We don’t have good drugs to help with the fatigue that comes with cancer and its treatment but we do have exercise which is effective for fighting fatigue,” adds Dr Edwards.”
You’d think this would have us all scrambling for running shoes and dumbbells, but there’s a widely held belief that too much exercise is bad for our immunity, she says.
“Yet almost all exercise is good for the immune system and the evidence that heavy bouts of exercise such as a marathon can undermine the immune system isn’t strong.”
As we age our muscle mass starts to decline – if we let it. But maintaining it with strength training helps shore up our immune system.
“In older people, the combination of shrinking muscle and declining immunity – often compounded by excess fat – is a perfect storm for a compromised immune system,” says Professor Newton.
Could this increase the risk of COVID-19?
“Low muscle mass – called sarcopenia – is much higher among elderly people and is increasing at a concerning rate because of lifestyle changes. While it’s too early to know if there’s a relationship between sarcopenia and the risk of COVID- 19 and its effects, there’s already good evidence of a link between sarcopenia and the incidence and severity of some other infectious diseases including pneumonia. It’s critically important to keep elderly people physically active including strength training to maintain their muscle mass.”
And if you still need more reasons to start an exercise habit – here’s another.
“There’s a raft of studies showing that exercise enhances the effectiveness of vaccinations,” Rob Newton says. “Exercising immediately before or after a vaccination helps the immune system develop immunity to the target disease and being physically fit through long-term exercise enhances vaccination effectiveness.”
How to build muscle (with or without the gym)
Strength training using weights or resistance bands at the gym or at home is the obvious way to build and maintain muscle. But it also helps to fit muscle-strengthening moves into our daily lives, says Kate Edwards. Stair climbing is one, fast walking uphill is another. So is using a sit-stand desk. “The benefit isn’t just that you’re not sitting all the time but the action of moving from a standing to a sitting position and back again is the same as doing a squat,” she says.
As for walking downstairs, leading with your heel rather than your toe pays off not only with safety (it reduces tripping) but also helps strengthen and lengthen the quadriceps muscles, adds Melbourne-based exercise physiologist, Darcy Smith, a spokesperson for Exercise and Sports Science Australia (ESSA), the peak body for exercise and sports science.
If you’re a beginner
For anyone new to strength training, Kate Edwards recommends the home workout videos on Exercise Right at Home, developed by ESSA. Many of these need no equipment (and one shows how to improvise with a pumpkin instead of a weight).
If you’re picking up weights after a few months off
Give your body time to adapt by using lighter weights and by lowering the number of times you lift them. “Instead of doing three sets of each exercise do two sets,” Smith says. “And warm up first using an isometric exercise like a wall sit ”.
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