Everyone knows the importance of warming up your muscles before exercising. But what exactly happens when we warm up our muscles, and are all muscles the same? You might be surprised to learn that the science behind this daily activity isn't always clear.
Now, in a study recently published in the Journal of General Physiology, a multi-institutional research team led by Osaka University, Jikei University School of Medicine, and the National Institutes for Quantum Science and Technology reveals how heating affects the contraction of different muscles, and how this may benefit people who need to improve their athletic performance.
Skeletal muscles respond to electrical signals from the nervous system, activating proteins in the muscle cells that allow us to move. The team previously explored how heart muscle contraction is affected by temperature, determining that our hearts can contract efficiently across a range of body temperatures.
Next, using muscle proteins and advanced microscopy, the team wanted to determine how temperature affects skeletal muscle: Do skeletal muscles have similar temperature sensitivities, or are they different from heart muscles?
The team found that some proteins in muscle cells act as temperature sensors and that heating affects the contractile systems of bones and the heart differently. "Our results show that there are differences in the sensitivity of proteins responsible for skeletal and cardiac muscle contraction to temperature," said co-lead author Taro Koyama. "Basically, the skeletal muscles that move our bodies are more sensitive to temperature than the heart."
The physiological significance of these findings becomes clear when functional differences between skeletal and cardiac muscle are taken into account. Skeletal muscles only produce a certain amount of force when needed, while the heart beats continuously.
"Skeletal muscle's higher dependence on temperature may allow it to contract relatively quickly when warming up, even with a slight increase in temperature due to light movement or exercise. This means that the muscle can store energy and rest when it is not needed. In contrast, the heart's lower temperature sensitivity may be beneficial in maintaining a continuous heartbeat regardless of temperature," explains co-lead author Shuya Ishii.
This study provides new insights into how pre-exercise warm-up can improve muscle performance at the protein level. The discovery that some muscle proteins act as temperature sensors may lead to a new hyperthermia strategy to improve skeletal muscle performance by warming the muscle. Incorporating appropriate warm-up activities into the daily routine of individuals, especially older adults, can improve their muscles and athletic performance, thereby reducing the risk of injury and helping to maintain their independence.