Fatigue is a feeling of constant exhaustion, burnout or lack of energy. One common method of assessing muscle electrical activity during exercise is surface electromyography, or sEMG. This approach, which consists of two traditional techniques, has been in use for more than 70 years. In the first, a single muscle is recorded using a pair of electrodes (metals that carry electricity through non-metals). In the second, the potential distribution of intra-muscular activity is evaluated using a grid of electrodes arranged in a compact rectangular pattern. These techniques, however, are limited to testing one muscle at a time. Because of this, we only partially understand how our muscles work together to perform various physical tasks.
Fatigue: Approach for Muscle Coordination
In a recent study, which was published on October 27, 2023, in the Journal of Physiological Anthropology; Professor Yoshihiro Shimomura of Chiba University’s Design Research Institute and a group of colleagues showed how to use bull’s-eye electrodes to measure the activity of multiple muscles simultaneously. They also looked into the device’s potential to gauge fatigue and create visual representations of muscle’s coordination during grasping tasks. Yali Xia from the Design Research Institute at Chiba University and Ms. Megumi Shimura and Mr. Akihiko Mizumoto from the Graduate School of Science and Engineering comprised his team.
“Ours is the first study to provide images of muscle coordination in the human body and to revolutionise the existing methodology of electromyography,” says Dr. Shimomura.
For this investigation, the researchers included nine adults who were free of illnesses or injuries. The task that the participants had to complete involved gripping. The participants in this exercise were given a pulley system. It had a handle at one end and a weight at the other. They were told to hold the handle with the hand they use the most often without using their forearms. The bull’s-eye electrode recorded muscle activation during the task. Entropy, a measurement of a system’s disorder, and root mean square were used to evaluate this system’s performance.
The findings suggest that an increase in entropy over time; indicates an increase in the disorder of forearm muscles due to fatigue. In addition, bull’s-eye electrodes provided an image of muscles activity at nine different points.
Thus, the study forms a base for further development of a multichannel sEMG system to increase the scope of measuring muscle activity. “Although our bull’s-eye electrode system has some limitations such as electric gain, it is a robust system that illustrates the muscle activity due to fatigue,” elaborates Dr. Shimomura
In conclusion, Dr. Shimomura states that “having access to an electromyogram can aid in the treatment of muscular disorders among urban workers and improve the health of older individuals.” It can also successfully alter how one uses their body to enhance their well-being and standard of living. In the future, we may utilise our bodies differently and experience improved wellbeing as a result of our increased understanding of our electromyogram.