In biological terms, posture is constant, continuous adaptation … Standing is in reality movement upon a stationary base … From this point of view, normal standing on both legs is almost effortless.
(F. A. Hellebrandt (1938))
Humans are designed to stand on two legs, but they are not designed to stand still. Standing is the position of choice for many tasks in industry but it can lead to discomfort if insufficient rest is provided or if unnecessary postural load is placed on the body. Some advantages of the standing work position are given in Table 4.1.
In everyday life, people rarely stand still for any length of time - if not walking or moving, they adopt a variety of resting positions that vary depending on the culture (Hewes, 1957; Bridger et al., 1994). Table 4.2 summarises some behaviours associated with unconstrained standing. In most occupational settings where people engage in 'industrial standing', they are denied the opportunity to practise these behaviours by the design of their workspaces and the design of their jobs.
Short periods of walking and gross body movements are vital to activate the venous pump and assist the return of blood from the lower limbs (Cavanagh et al., 1987; Stranden, 2000), so the idea that workers should stand still is physiologically and mechanically unacceptable. Anecdotal evidence across many cultures and over time tells us that people who do have to stand for long periods use standing aids such as the staff of the Nilotic herdsman or the spear of the sentry. An experiment on constrained standing by Whistance (1996) demonstrated that even unpractised users spontaneously make use of such aids when they are provided.
Table 4.1 Some advantages of the standing work positiona
Reach is greater in standing than in sitting.
Body weight can be used to exert forces.
Standing workers require less leg room than seated workers.
The legs are very effective at damping vibration.
Lumbar disc pressures are lower.b
It can be maintained with little muscular activity and requires no attention.c
Trunk muscle power is twice as large in standing than in semi-standing or sitting.d
a Singleton (1972).
b Nachemson (1966).
c Hellebrandt (1938).
d Cartas et al. (1993).