Introduction
Physiology of work is part of human physiology and of occupational hygiene. It describes how the body meets the demands of physical and mental work, what changes in its systems during work, and where the limits of working capacity lie. Its practical aim is to set work loads that a person can carry without harm to health.
What work physiology studies
- Physiological changes in the human organism during physical and mental work.
- Working capacity.
- Physical and mental fatigue.
- Professional stress and distress.
- Physiological problems of night and shift work.
- Ergonomics problems.
- Physiological changes in response to the effects of working environmental factors, and the combined effect of different environmental factors and work.
- Psycho-physiological changes during work.
- Individual differences in working ability and the choice of profession.
- Health and safety of work.
Energy expenditure
- Physical activity requires energy, which is provided by the food consumed.
- Food has to be digested, assimilated, absorbed and converted before it provides energy.
- Total daily expenditure is the sum of basal metabolism (energy for the vital functions at rest), the specific dynamic action of food, and the energy of activity. Work adds the largest and most variable part, so heavier work needs a higher energy intake.
- Work is graded by its energy cost, from light through moderate to heavy and very heavy work. The more muscle mass involved and the faster the pace, the higher the cost.