Sore muscles: why staying tuned helps

Christiane Fux studied journalism and psychology in Hamburg. The experienced medical editor has been writing magazine articles, news and factual texts on all conceivable health topics since 2001. In addition to her work for, Christiane Fux is also active in prose. Her first crime novel was published in 2012, and she also writes, designs and publishes her own crime plays.

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Athletes know the phenomenon: after the second training session, the sore muscles are less severe than after the first. The overload causes the muscles to arm themselves against further injuries. Obviously, certain immune cells play a key role that was previously only known in a completely different function: the T cells.

The immune system is not just there to protect the body from intruders. The immune cells also clear out diseased cells and repair damaged tissue. This is also the case when tiny tears appear in the muscle fibers during excessive exercise. The immune cells that are called in to repair, trigger an inflammatory reaction - this makes the muscles ache.

For a long time it had been assumed that the inflammatory reaction is less severe after further exposure because the body gets used to the strain. This also explains why the muscle soreness is less pronounced.

Paradoxical phenomenon

In fact, the opposite is the case: the inflammatory reactions are even somewhat stronger - but still cause fewer complaints. This result surprised the researchers headed by Robert Hyldahl and Michael Deyhl from Brigham Young University.

The researchers had sent a group of healthy volunteers to two demanding training sessions 28 days apart. With the help of an isokinetic dynamometer, in which the leg works against resistance, the researchers were able to measure exactly how great the effort was by the participants.

For comparison purposes, they had each participant work with only one leg. Both before and two days after the training units, the researchers took muscle samples from the test subjects - from the trained and untrained leg.

T cells control healing

They examined the muscle samples for the activity of various immune factors and inflammatory processes. In the process, they unexpectedly came across a higher amount of T cells that were in the damaged muscle fibers after the hard training. “With T cells, we have only thought of combating pathogens so far,” explains Hyldahl.

In this case, however, the T cells actually helped the muscles to adapt to the load. They call on a large number of immune cells with a repair function and possibly control their work. The muscle is repaired faster and more effectively.

Orderly repair troops

This stimulates the inflammatory process on site - interestingly, this does not cause more complaints. “A lot of people believe that inflammation is a bad thing,” says Deyhle. "But if they are properly regulated, they are a normal and healthy process that helps the body to heal itself." If this happens in an orderly manner, it does not seem to have to cause any pain in the muscles.

The fact that many athletes take anti-inflammatory drugs such as ibuprophen and acetylsalicylic acid after exercise may therefore not have the desired effect.

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