Exercise has many benefits for our bodies, including making our muscles stronger and toned. But how exactly does exercise make this happen? That's a question that some scientists have been trying to answer. Do the chemicals in our bodies or the physical forces from movement contribute to muscle growth? The answer could be the key to helping people with muscle injuries and neurodegenerative disorders.
MIT engineers have come up with a unique solution to this question. They have created a special mat for cells that can help scientists understand how exercise affects muscles on a microscopic level. This mat is quite similar to a yoga mat, but it's made from a soft, Jell-O-like material called hydrogel and embedded with tiny magnetic particles.
To make the gel behave like an exercising muscle, the researchers placed an external magnet under the mat, which caused the embedded particles to move back and forth. This motion made the gel vibrate, similar to the way our muscles do during exercise. They controlled the frequency of the wobbling to mimic the forces that real muscles experience during physical activity.
Next, they grew a layer of muscle cells on the gel's surface and turned on the magnet's motion. They wanted to see how the cells responded to this "exercise" by vibrating them magnetically.
The results of MIT engineers' experiments show that regular mechanical exercise can help muscle fibres grow in the same direction. These exercised fibres also contract in unison. This has potential applications in creating strong, functional muscles for soft robots and repairing damaged tissues.
Ritu Raman, an engineer at MIT, says, "We hope to use this new platform to see whether mechanical stimulation could help guide muscle regrowth after injury or lessen the effects of ageing. Mechanical forces play a really important role in our bodies and lived environment. And now we have a tool to study these forces."
The experiments showed that the muscle cells exposed to regular mechanical motion grew longer compared to cells that were not exercised, which remained circular. The "exercised" cells grew into fibres that aligned in the same direction, while the non-moving cells were more like a messy haystack of misaligned fibres.
The muscle cells used in this study were genetically engineered to contract in response to blue light, which is a noninvasive stimulus. This allowed the researchers to avoid potentially damaging the cells with electrical pulses. When they shone blue light on the muscles, they found that the control cells were beating in different directions, whereas the aligned fibres all pulled and beat together, in the same direction.
Mrs Raman calls the new workout gel "MagMA" (short for magnetic matrix actuation), and she believes it can be a quick and noninvasive way to shape muscle fibres and understand how they respond to exercise. She plans to grow other types of cells on the gel to study how they react to regular exercise.
This study has received support from the US National Science Foundation and the Department of Defense Army Research Office.