ABSTRACT
Muscle activity is a cornerstone in physical activity during work and leisure, and is often the greatest stress that the body encounters in the course of daily life. Skeletal muscle accounts for about 30%–50% of total body mass. When skeletal muscle is activated by the nervous system to generate mechanical energy, that is, force or work, such as is experienced in almost every type of task that an ergonomics/human factors (E/HF) specialist might be required to analyse or design, the body must make rapid integrated adjustments from the cell level to the organ systems and coordinate responses within the body. These responses are vital for the delivery of chemical energy for the conversion to mechanical energy that can exclusively occur in muscle tissue. During the resulting energy turnover (i.e. breakdown of chemical energy), thermal energy – or heat – is produced alongside with the mechanical energy, and therefore at the same time as executing muscle activity, bodily responses must ensure heat dissipation.
