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Everyone understands the benefits of warming up your muscles before a workout. But what happens when we warm up our muscles, and are all muscles the same? You might be shocked to learn that the science behind this commonplace activity hasn't always been obvious.
In a study recently published in the Journal of General Physiology, a multi-institutional research team led by Osaka University, The Jikei University School of Medicine, and the National Institutes for Quantum Science and Technology revealed how heating affects muscle contraction and how this may benefit populations in need of improved exercise performance. Skeletal muscle contracts in response to electrical signals from the nervous system, which activate proteins in muscle cells and allow us to move. The team previously explored how cardiac muscle contractions are affected by temperature, determining that our heart can contract efficiently within the body temperature range. Next, using muscle proteins and advanced microscopy, the research team wanted to determine how temperature affects skeletal muscle: do skeletal muscles have similar temperature sensitivity, or are they different from the muscles of the heart? The research team found that some of the proteins in the muscle cells act as a temperature sensor, and that heating affects skeletal and cardiac contractile systems differently. "Our findings point to differences in the temperature sensitivity of proteins responsible for contraction in skeletal vs cardiac muscles," says co-lead author Kotaro Oyama. "Basically, the skeletal muscle that moves our body around is more sensitive to heating than the heart." The physiological significance of these findings will become clear when the functional difference between skeletal and cardiac muscle is considered. While skeletal muscle only generates a certain amount of force when required, the heart is meant to beat continuously. "The higher temperature dependence of skeletal muscle may allow it to contract relatively quickly upon warming up, even from slight warming due to light movement or exercise. This means that the muscle can save energy and rest when not needed. In contrast, the lower temperature sensitivity of the heart may be beneficial for maintaining a continuous beat, regardless of temperature," explains co-lead author Shuya Ishii. (ANI)
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