The latest confirmation that exercise leads to healthier ageing is a study that identifies a ‘niche’ in bone marrow where new bone and immune cells are produced.
Research from the Children’s Medical Center Research Institute (CRI) in Texas concludes that this crucial niche requires “movement-induced stimulation” from walking or running, reports Science Daily.
The study authors suggest potential new therapies might increase bone formation and immune responses, particularly in the elderly.
“Past research has shown exercise can improve bone strength and immune function, and our study discovered a new mechanism by which this occurs,” said research lead Sean Morrison, PhD, CRI director.
“Our study raises the possibility that there might be a lot more that depends on mechanical stimulation than we imagined,” he told Inverse.
“We know that exercise is really good for you, but we’re getting a more complete picture of why it’s good for you.
“As we age, the environment in our bone marrow changes and the cells responsible for maintaining skeletal bone mass and immune function become depleted.
“We know very little about how this environment changes or why these cells decrease with age,” said Dr Morrison.
“We think we’ve found an important mechanism by which exercise promotes immunity and strengthens bones, on top of other mechanisms previously identified by others.”
As The Scientist puts it: “Ageing weakens bones and running can help strengthen them.”
Before the CRI research, it was suspected that mechanical forces acted on the bone itself and the soft marrow within was insulated. The new view is that arteriolar blood vessels transmit the movement-induced mechanical forces and thereby “stimulate the proliferation of bone- and immune-cell precursors”.
Researchers found that older mice that ran on a wheel produced more of a growth factor called osteolectin and more new bone cells compared with older mice that didn’t run.
As bone cells grow, they secrete growth factors that encourage immune cells to form, which improves the animals’ ability to fight off bacterial infections.
When researchers ‘turned off’ the ability of bone-forming cells to sense pressure caused by movement, the formation of new bone cells lessened, leading to thinner bones and less capacity for the mice animals to clear a bacterial infection.
The study noted that increasingly common sedentary lifestyles are associated with more chronic disease.
“Many diseases, such as heart disease and type 2 diabetes, have been reported to be associated with limited physical activity.”
Nature called the study’s link between movement and immune response “exciting”.
“If relevant to humans, the work could have direct clinical applications. For example, the pathway uncovered in the current study could be harnessed to develop better therapies to strengthen immune cell output triggered by movement.”
They want further research to identify whether increasing certain cells in bone marrow could “provide protection against other disease-causing bacteria, or even viruses, or whether it might also boost vaccination responses”.
“We can’t say it for sure,” Dr Morrison said. “But there’s a remarkable degree of similarity between the blood-forming system in mice and the blood-forming system in humans.
“When astronauts go up into space, and their bones become unloaded, their bones become thinner, and their immune system goes down,” he explained.
“So, these observations are completely consistent with things that we know happen in humans.”
Inverse advises us to use this new awareness.
“Next time you’re climbing a set of stairs, you can think of the movement of your feet reaching deep within the smallest blood vessels inside your bones, spurring on the creation of crucial new cells.”
Are you conscious that a sedentary lifestyle is increasingly being confirmed as a dangerous precursor to disease and ageing? Are you being mindful about continuing to exercise as you age? What works for you?
Read more: The big ‘O’ and ageing: what to expect
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