Biological heat

Metabolic Heat Production Calculator

The body converts chemical energy into mechanical work and heat. Enter a metabolic power, external mechanical work rate and duration to estimate the internal heat production represented by the difference.

Estimate metabolic heat production

Why physical activity increases heat production

Human movement requires metabolic energy. Only part of that energy appears as external mechanical work. The remainder is largely dissipated as heat, which must be transferred away or temporarily stored in body tissues.

Metabolic heat is only one part of heat stress

NIOSH describes occupational heat stress as the combined effect of metabolic heat, environmental heat and clothing or personal protective equipment. A person can therefore face substantial heat stress even when metabolic heat production itself has not changed.

Why this is not a body-temperature predictor

Core temperature depends on the balance between heat production, heat gain, heat loss and physiological responses such as skin blood flow and sweating. A simple energy difference cannot reproduce that whole-body thermoregulation problem.

Sources and further reading

CDC/NIOSH: Heat Stress and Workers - explains the combined roles of metabolic and environmental heat.
CDC/NIOSH: Workplace Recommendations for Heat Stress - discusses reducing metabolic demands as part of heat-stress control.