Energy metabolism heat production and physical work

Assessment of the protection requirements in a cold environment requires information about the energy metabolism of the individual. Metabolic rate is related to the intensity of physical work and can be easily determined from measurements of oxygen consumption. Tables are readily available that allows its estimation during different types of activity (ISO-8996, 2004). With few exceptions the values for metabolic rate also indicate the level of metabolic heat production. In most types of muscular work the mechanical efficiency is negligible. Table 14.1 can be used for a rough estimation of the metabolic rate and associated heat production.

Table 14.1 Examples of metabolic energy production associated with different types of work. Modified from IS08996. Values refer to a standard man with 1.8 m2 body surface area

Class

Average metabolic rate (Wm2)

Examples

Resting

65

Resting

Low

100

Light manual work; hand and arm, work; arm and leg work; driving vehicle in normal conditions; casual walking (speed up to 3.5 km/h)

Moderate

165

Sustained hand and arm work; arm and leg work; arm and trunk work; walking at a speed of 3.5 km/h to 5.5 km/h

3 High

230

Intense arm and trunk work; carrying heavy material; walking at a speed of 5.5 km/h to 7 km/h

Very high

290

Very intense activity atfast pace; intense shovelling or digging; climbing stairs, ramp or ladder; running or walking at a speed of > 7 km/h

Very, very high (2h)

400

Sustained rescue work; wild land fire fighting

Intensive work (15 min)

475

Structural fire fighting and rescue work

Exhaustive work (5 min)

600

Fire fighting and rescue work; climbing stairs; carrying persons

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