While top sports teams like the Springboks all know the importance of warming up their muscles before a game, it has not always been clear as to what is actually going on when muscles are warmed up, and whether all muscles are the same. Now, in a study recently published in the Journal of General Physiology, a Japanese research team has revealed how heating affects the contraction of different muscles, and how this might benefit populations in need of improved exercise performance as well as on the sports field.
Skeletal muscle contracts in response to electrical signals from the nervous system, which activate proteins in muscle cells, resulting in movement. The team previously explored how cardiac muscle contractions are affected by temperature, determining that the heart can contract efficiently within the body temperature range.
Next, using muscle proteins and advanced microscopy, the Osaka University-led team wanted to determine how temperature affects skeletal muscle: do skeletal muscles have similar temperature sensitivity, or are they different from cardiac muscle?
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.
This study provides new insights into how, at the protein level, warm-up before exercise enhances muscle performance. The discovery that some muscle proteins act as a temperature sensor may lead to a new hyperthermia strategy, in which skeletal muscle performance is improved by warming up the muscle. Incorporating appropriate warm-up routines into the daily lives of individuals, particularly the elderly population, could improve their muscle and exercise performance, thereby reducing the risk of injury and helping to maintain their independence.
Source: Osaka University
