When you exercise your body, you’re actually damaging it. In order to generate force, the fibers in your muscles contract. But at the same time, the external load becomes too great and they are forced to lengthen even though they don’t want to. This is called eccentric contractions, and it causes tiny tears and other damage to your muscles.
Luckily, your body is prepared for this. Lying in wait between the membranes of the muscle fibers are skeletal stem cells. Once the muscle is damaged, they immediate go to work to repair the damage. In the case of injury, they help heal the muscle back to a functioning state. In the case of exercise, their repair job does more than replace the damages, it also adds new muscle thus making you stronger.
But the human body is a complex thing and almost nothing ever does its job alone. In a recent study published in PLoS ONE, University of Illinois researcher Marni Bopart led a team to see if another type of stem cell called mesenchyman stem cells (MSCs) might also be important to skeletal muscle health.
It was already known that MSCs are important for muscle repair in response to non-physiological injury, such as in the response to chemical injections that significantly damage muscle tissue and induce inflammation. In order to determine whether or not they’re also important for muscle health in response to exercise, Bopart turned to mice.
After making mice take part in force downhill running on a treadmill, the researchers found that the mechanical strain caused levels of MSCs in the muscles to rise. On further investigation, they determined that though MSCs don’t directly repair damaged muscle tissue, they release growth facturs that spur other cells in muscle to fuse and generate new muscle, providing a cellular basis for enhanced muscle health following exercise.
The authors hope that the discovery will lead to future therapies to prevent muscle mass loss in sick, disabled and elderly patients.
The douche bag flexing in the mirror in the corner of the gym hopes it makes its way into his next supplement shake.