MANY workers in a wide-variety of different jobs have to stand for long periods on the same spot while working. Working in a standing position can be a problem when it is not possible to alternate the standing posture with other postures and when the duration on a daily basis is too high. Prolonged standing can be defined as standing more than one hour without moving from the workstation and standing more than four hours a day. This article looks at the risks and health effects of prolonged standing work and preventive measures.

Extent of the problem

.Prolonged standing can cause fatigue, leg cramps and backache. In the longer term, this may damage the ankle, knee and hip joints and make muscles ache[5]. Prolonged standing is also known to be related to a variety of other health effects like cardiovascular disease, preterm birth, chronic venous disorders like varicose veins, circulatory problems, and increase of stroke risk. For the best health and safety outcome, workers should be able to adopt a variety of body positions: preferably workers should be able to vary between sitting, standing and moving about.

Health effects of prolonged standing

Prolonged standing (on a regular basis) at work can lead to adverse health outcomes. Due to standing positions the worker may feel discomfort and fatigue particularly in the lower limb muscles (legs and thighs), lower back and feet. Prolonged standing is also associated with other health effects. It is known that prolonged standing for more than 8 hours on a regular basis is strongly related to chronic venous insufficiency, musculoskeletal pain of the lower back and feet preterm birth, low blood pressure, upper and lower leg pain and spontaneous abortions were health risks associated with working conditions that required prolonged standing[6] [7]. It should be taken into account that prolonged standing is especially harmful when the worker does not move at all and remains standing on the same spot continuously. When the worker is able to move, within a circle with a radius of as little as one meter, the work is performed in much more dynamic and thus healthier way.

Looking at the combination of (types of) standing and lower limb disorders, there are other forms that need to be taken into account in the approach since they result in mechanic type of lower limb load and less lower leg blood flow. This concerns kneeling (a body posture where the worker supports him/herself with one or two knees on the ground) and squatting (a low sitting type of body posture with at least one knee angle of less than 90° in which the worker often touches the body with his/her feet).

If a worker has an existing health problem, such as sciatica related to a back problem or painful joints due to rheumatism, prolonged standing can provoke the associated pain and exacerbate the condition.

Musculoskeletal disorders (MSDs)

Standing is a natural human posture and by itself poses no particular health hazard. However, when prolonged standing occurs, this decreases the circulation of blood and reduces the nutrient supply to muscles, thus allowing muscular fatigue to set in. This may result in lower limb MSDs (musculoskeletal disorders). The consequences are:

Fatigued legs, including an increased tendency to fall by slipping and tripping and a higher risk for developing lower back pain.

Insufficient blood flow may lead to discomfort / fatigue and pain in neck and shoulders.

Insufficient blood flow can also lead to circulatory problems in the legs and lead to pain, varicose, and swelling of the legs.

Development of venous disorders of the lower limbs and discomfort at the ankle/foot. Eventually, discomfort may lead to ankle / foot complaints.

Immobilization of the joints (spine, hip, knees and feet) may occur and lead to degenerative damage of the joints and pain as a consequence. This immobility can later lead to rheumatic diseased due to degenerative damage to the tendons and ligaments.

Standing places significant pressure on the joint of the hips, knees, ankle and feet but without any significant movement of it. This reduces the normal lubrication and cushioning of synovial joints, causing them to tear. The combined effect of pressure and tearing can cause extensive amounts of pain and make it difficult to move or walk

Temporary discomfort in the legs and feet and stiff joints and stiffness in the neck and shoulders from lack of movement and constrained posture.

When duration increases, the risk of complaints also increases.

Risk factors

When static standing occurs, it decreases the circulation of blood and reduces the nutrient supply to muscles, thus allowing muscular fatigue to set in[8] and eventually pain in the legs, back, neck and feet. Working in a standing position can be a problem when it is not possible to alternate the standing posture with other postures and when the duration on a daily basis is too high.

Length of standing time

Research shows a clear link between the time workers must stand and symptoms related to lower back complaints and lower limb complaints.

Table 1 Low back complaints and lower limb complaints caused by working in standing position from two longitudinal studies[9][10]

Working while standing: Low back complaints that occurred in the past 12 months compared to workers who stand < 15 minutes a day at work Lower limb complaints that occurred in the past 12 months compared to workers who stand < 15 minutes a day at work

From 15 minutes a day up to 2 hours a day + 5% Not available

From 2 hours a day up to 4 hours a day +50% N o t available

More than 4 hours a day +100% +70%

Summarising the information, possible thresholds of standing that may become a risk factor particularly are considered to be marked by these indicators: L o w back complaints are noticeable when standing daily from 15 minutes onwards and are increasing from 30 minutes onwards.

One in seven workers feels burdened when standing most of the time while workin Exposure to standing at least 25% of the working time coincides with experiencing MSDs.

Up to 2 to 2.5 hours a day of standing may be considered ‘low risk’ considering ‘feeling burdened’.

When standing 2 hours a day up to 4 hours a day low back complaints increase by 50%.

When standing more than 4 hours a day low back complaints increase by 100%.

The risk will also depend on other factors such as the standing posture needed to do the job, if a foot pedal has to be operated, as in some factory work or train driving, or any twisting, reaching or manual handling involved.

Static standing and dynamic standing

It is important to realize that there is a significant difference between prolonged standing and dynamic standing regarding health effects. Prolonged standing is standing on exactly the same spot. Dynamic standing means there is a possibility to move about. Besides a difference in the mechanic load on musculoskeletal structures, there is a substantial physiological difference between static and dynamic standing. This is closely related to three categories of force (vis) that participate in venous blood return, depending on whether a force is acting from behind on the sides or in front of the (lower) leg blood mass. All three of these ‘blood flow’ propulsion mechanisms can work correctly even if a worker moves about in only one square meter. An approach to move about ones workstation in a dynamic fashion even if the available space is limited should thus be part of a prevention approach.

Symptoms and health complaints

The most commonly reported symptoms appear to be discomfort, fatigue and swelling in the legs. More specified symptoms and health effects are[11]

Painful feet and legs

Swelling in feet and legs

Bunions / corns

Heel problems, including plantar fasciitis / heel spurs

Achilles tendonitis

Varicose veins

Orthopaedic changes to the feet

Low back pain

Restricted blood flow

Immobilisation of joints

Arthritis in knees and hips

Stiffness in neck and shoulders

Problems in pregnancy

High blood pressure

Heart and circulatory problems

Workers required to spend too much time on their feet are at greatly increased risk of pain and discomfort affecting feet, shins and calves, knees, thighs, hips and lower back.

Other health effects

Prolonged standing may increase the risk of cardiovascular disease. This is because standing too long can result in blood pooling in the legs, increased pressure in the veins and increased oxidative stress, all of which contribute to an increased risk. Workers who primarily stand on the job are twice as likely to develop heart disease compared to workers who primarily sit [12]. Walking or standing more than six hours per day has been linked with pre-term births, low birth weights as well as high blood pressure for the mother[13]. Additionally, prolonged standing is also associated with chronic venous disorders, circulatory problems, increase of stroke risk.

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