Musculoskeletal disorders and prolonged static standing

Introduction

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

Surveys in some European Union (EU) countries have suggested that there is a trend towards increased static work postures and prolonged standing and sitting at work, although there is no data about this trend available after 2005^[1]. According to European statistics, one in five workers in the European Union (EU) (20%) spend most of their working time standing up, with Spain (43%) and Romania (36%) having the highest share^[2]. Others suggest that in Europe, between one third and half of all workers have to stand at least four hours of their working day^[3]. Standing work may have increased in jobs where the worker must attend to the public, as it is thought this creates a better image to the client^[4].

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]

Summarising the information, possible thresholds of standing that may become a risk factor particularly are considered to be marked by these indicators:

• Low 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 working
• 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^[1]

• 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^[2]. 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^[14].

Workers at risk

Types of jobs

There are many different jobs that require prolonged standing. These include a variety of jobs: waiters and waitresses, kitchen staff, welders and cutters, retail salespeople, electricians, pharmacists, school teachers, physiotherapists, childcare workers, bartenders, assembly line workers, machine operators, security staff, engineers, catering staff, library assistants, hair dressers, laboratory technicians, nurses, care workers and other health care workers, and receptionists. Many of these workers who have to stand at work are in lower-paid jobs. There is also some evidence that temporary workers are more exposed to standing work^[1]. Those in low paid jobs often have little discretion over how they work and when they can take breaks to sit or move around.

Women

Men and women are differently affected by work-related MSDs, partly due to the differing nature and circumstances of the work they perform. Women are –compared to men- significantly more exposed to prolonged standing and walking (e.g. in the retail sector, the hotel and catering sector, cleaning work, education or in health care) and report more problems concerning hips, legs and feet. EU-OSHA also points out that women may be exposed to prolonged standing together with other MSD risks: ‘As an example, while workers in the hotel, restaurant and catering sector more often perform monotonous and repetitive tasks, carry heavy loads and are exposed to tiring postures, their counterparts in the healthcare sector report complex tasks, frequent interruptions and working with computers. Both groups are highly exposed to prolonged standing and other multiple physical and organisational risk factors that may lead to MSDs.’ Typical male jobs such as in construction or warehouses, while involving prolonged standing, often involve more walking around compared with typical female jobs^[15]. Women are more concentrated in low paid jobs characterised by less control over how they work and when they can take a break from standing work. A work dress code or uniform may require women to wear high-heeled shoes, but standing in heels of more than 5 cm can affect normal posture and leg muscle use^[16]. Wearing tights which restrict the toes can also can also cause problems. Standing work stations designed for the average male may be ergonomically unsuitable for women (or very tall or short men). It may well be that different types of intervention strategies work better for women than for men and vice versa.

Pregnant women who habitually stand at work have a higher risk of high blood pressure and having a premature birth. Their standing time per day must be limited. Regulations in the EU on pregnant workers include the provisions for making such temporary changes to duties^[17].

Older workers

Available national data show also shows that MSDs recognised as occupational diseases are more present among older workers and many studies show that the prevalence MSDs increases with age^[18]. Musculoskeletal changes linked to aging such as loss of muscle strength and reduced joint mobility play a role in this. However, cumulative exposure to unsatisfactory standing working conditions over the work-life course may have a greater influence on the development of work-related MSDs than age per se. Therefore to prevent MSDs in the workplace, it is necessary to address the aging work force and the sustainability of work, including in relation to standing work. As the workforce ages there will be also more workers with chronic diseases such as rheumatic and arthritic conditions . Standing work can be particularly problematic for someone with a chronic musculoskeletal disorder. As working in fixed postures is not recommended for workers of any age, to improve the sustainability of work the first approach should be to improve the working conditions of all workers, with specific additional considerations for ageing workers or workers with a chronic condition if necessary^[19].

Regulations and guidelines

All employers in the EU are required to carry out risk assessments and bring in preventive measures based on the assessments^[1]. In selecting the measures, they should avoid risks where possible and adapt work to the worker. The risk assessment must also take account of any workers particularly sensitive to the risk, for example, workers already suffering from sciatica or knee problems, while employment equality legislation requires employers to provide reasonable accommodation to disabled workers^[21].

Any workers who habitually use display screen equipment as a significant part of their normal work are covered by regulations on display screen equipment, which include providing them with a suitable workstation and chair^[22]. Legislation on workplaces covers the provision of rest areas with seating which has a back rest^[23]. Legislation on work equipment requires work equipment to be suitable for the work to be carried out and for employers to take account of ergonomic principles^[24]. Legislation on construction sites includes provisions on rest areas^[25]. Legislation covering pregnant workers requires employers to assess risks and decide what measures should be taken^[17]. This includes risks from movements and postures, mental and physical fatigue and other physical burdens connected to a person’s work. Employers should also provide protective footwear where needed, which should be suitable and comfortable^[2]. This legislation comes from European Directives setting minimum standards which the Member States transpose into national legislation. In the UK, regulations on workplaces refer to standing: If workers are able to perform their duties, or a substantial part of them, sitting down, employers must supply suitable seats^[27]. The approved code of practice on the regulations requires employers to provide suitable seats for workers who have to stand to carry out their work, if the type of work gives them an opportunity to sit from time to time and provide suitable seats for workers to use during breaks^[27].

General provisions on the prevention of musculoskeletal disorders in Sweden state that workstations, jobs and work environment conditions should be designed and arranged in such a way that risks of physical loads both static and dynamic which are dangerous to health or unnecessarily fatiguing or stressful are averted^[28].

The Dutch Health Council defines standing as a posture in which the body rests on the legs and the legs are not be moved further than within a circle with a radius of one meter relative to the original position of the body. It sets maximum standing times, defining jobs having a risk due to prolonged standing when standing as more than 1 hour without getting away from the workstation and standing more than 4 hours a day^[29].

Research by Waterloo University recommends not standing for more than 15 to 30 minutes in an hour^[30]. In Switzerland the general advice during a working day is: sitting 60%, standing up 20% and being mobile 20%^[31]. These positions need then to be alternated as often as possible.

Interventions

The use of prolonged static or fixed postures while working, including prolonged standing and prolonged sitting, should be avoided. This means that standing work should not just be replaced with sitting work. The effects of prolonged standing can be eliminated or reduced through work organisation (for example, limiting time spent standing in the workplace) and workstation design, job design, flooring, anti-fatigue mats and personal protective equipment. The first question to ask is ‘Does the work have to be done standing up?’. Where prolonged standing cannot be avoided, ways to make it more dynamic and promote movement are needed.

What employers can do

Workplace design Organizations should design workstations that are conducive to good health, and both job design and the workstation should be adapted to the individual. The physical layout of the workstation, tools, placing of keys, controls and displays determine the body positions workers will assume when performing their tasks. If the workspace is inadequate for the task, workers will have less freedom to move around and refresh tired muscles. They may also be forced to assume awkward positions. This lack of flexibility in choosing body positions contributes to health problems6. In a well-designed workplace, the worker has the opportunity to choose from a variety of well-balanced working positions and to change between them frequently^[1]

Additionally, workers should be able to adjust the height of their workstations to fit their body size^[32]. Adjustable workstation heights are relevant to both standing and sitting tasks, and may, depending on the tasks, allow a worker to alternate between sitting, standing and perching in a semi-standing position. A correct workplace design helps to prevent unfavorable working positions. The use of the following flowchart can help with making the right basic choices.

It is important to question whether a job always has to be carried out standing, for example, receptionists. Supermarket checkout staff should not have to stand at the checkout all the time, although they will need to stand to handle heavier objects.

Designing good workplaces does not only mean assessing standing work, but also looking at other ergonomic factors. Some jobs involving prolonged standing will involve other MSD risks, like handling work, repetitive work or awkward postures. Changes to the workplace or tasks may be necessary if seating is to be provided to restrict standing work.

Workstations that allow dynamic standing

Dynamic standing means there is a possibility to move about. It appears that even having as little space as one square meter to move around on can reduce the problems related to standing work.

Equipment

Other equipment which may be useful to avoid prolonged standing includes ‘perching’ stools which can be used in a semi-standing position. Staff supervising the public in art museums often use them, so they can change from standing, perching and walking. Foldaway stools which can be easily carried may be useful in some circumstances. Foot rails and individual footstools, to support one foot, interchangeably, allow posture change while standing. If seating such as chairs, stools or sit-stand (perching stools) are provided to restrict standing they should be easily adjustable and comfortable. They should be suitable for the work being done and be useable in the workspace. It is no good providing seating if the workspace layout or the tasks restrict its use.

Job design

Basic principles of good job design for standing work include the following:

• Provision for worker training (on proper work practices and use of rest breaks);
• Job rotation among group of workers (moves workers from one job to another to shorten time standing)^[33]

• Job enlargement gives workers more and varied tasks to increase body positions and motions;
• Avoidance of extreme bending, stretching and twisting;
• Work paced appropriately;
• Allowance for frequent rest breaks (standing work is tiring).

Flooring

Materials that provide flexibility such as wood, cork, carpeting, or rubber are gentler on workers’ feet. Concrete or metal floors can be covered with mats. Mats should have slanted edges to help prevent tripping. However, thick foam-rubber mats should be avoided. Too much cushioning can cause fatigue and increase the risk of tripping^[32][6].

Anti-fatigue matting

Anti-fatigue matting may also alleviate foot discomfort and fatigue. It encourages subtle movement of the leg and calf muscles, which in turn promotes an easier flow of blood back to the heart reducing foot fatigue^[34].

Adequate footwear The health effects of prolonged standing can also be minimized with the use of adequate technical interventions, like footwear. Footwear should not change the shape of the foot, have enough space to move toes, have shock absorbing cushioned insoles and heels no higher than 5 cm^[16]. There are also special insoles for shoes that can be used when soft mats or chairs are not available. In jobs requiring protective footwear, this should be suitable and comfortable^[35] and if worn by women it should be designed for women. Workers should be consulted and given a choice. Dress codes should allow for wearing comfortable shoes.

Breaks and exercise

Give regular breaks during which workers can sit. Several small (micro) breaks are considered to be more effective on fatigue than one long break. As far as possible, the moment when to take breaks should be under control of the worker. Workers should be encouraged to stretch as well as move. Workplace wellness programmes can be carried out during set break times that focus on reducing prolonged standing at work, stretching and increasing blood flow^[11]. Walking is especially effective to increase blood flow in the body, for instance by taking a walk during lunchtime. Also effective is providing training programmes for selected workers who can then train and guide their colleagues.

Interventions for the older workers or workers with an existing musculoskeletal condition Employers have duties to protect the health and safety of more vulnerable workers. The first priority should be to make work safer, healthier and easier for all the workforce. However, older workers or a worker with a chronic musculoskeletal condition may need additional measures. This includes providing additional support for worker requirements and enhancing workplace adjustability and workplace design. BAuA and IG Metall selected relevant criteria and described 30 tools that are age proof. They also included MSE usability^[36]. Individual accommodations for someone who has problems to stand for long could be, depending on the work they do, the use of a portable perching stool, more frequent breaks or job rotation.

Early intervention

Workers should be encouraged to report any problems associated with standing work, so they can be addressed as soon as possible and before they become worse. Addressing problems promptly is likely to save time and money.

Consultation

Employers are required to consult workers and their representatives on health and safety. Knowing how the work is done in practice and what the problems are puts them in a good position to help find practical solutions. The active participation of workers is important for determining ergonomic solutions.

What workers can do

What can workers do to reduce discomfort from standing at work.

Use the adjustability options of the workplace

• Adjust the height of the work according to body dimensions, using elbow height as a reference.
• Organise your work so that the usual operations are done within easy reach
• Always face the object of work.
• Keep your body close to the work, avoid bending forward and/or reaching.
• Adjust the workplace to get enough space to change working position.
• Use a foot rail or portable footrest to shift body weight from both to one or the other leg.
• Use a seat whenever possible while working, or at least when the work process allows for rest.
• Where your work allows, move between sitting, standing and moving around.

Sitting

Explore the possibilities to sit and give your feet a rest and make sure you explain to your boss what you are going to do. For example, sitting while answering the phone or filling in paperwork may be appropriate for your workplace, especially if there are no customers around.

Sitting during lunch break

Make sure you use breaks and try to sit, preferably with your legs up, which promotes blood circulation due to the reduced effects of gravity. Taking off your shoes while resting gives your feet the opportunity to cool off, due to the evaporation. However, some moving around and stretching is also important.

Move during standing

If a worker works on a small floor area, remember to:

• Occasionally shift weight from one leg to another
• Try to move about and make small steps, Dutch casino workers call this ‘table dancing’. Even if you can only move a little, it is important to do this. Standing becomes more dynamic and therefore healthier.
• If you have a stool: take the weight of your legs once in a while
• If you need to pick tools or supplies: avoid back bending and rotating, it is better to take one step to do this than not to move at all,
• Try to walk at least once an hour, even if this is a short walk, and do some stretching if possible.

Wear the right shoes and socks

• Wear shoes that fit well
• Have your shoes fitted by a shoe vendor later in the day, because your feet will be the biggest, usually because of the swelling of the foot and a slight compression of the arch of the foot.
• Wear shoes without high heels but avoid completely flat shoes and using slippers.
• Avoid wearing shoes with a narrow nose.

Wear support stockings

Support stockings provide support to the muscles and blood vessels of the lower leg, reducing edema / swellings and promoting blood circulation. Alternatively, you can also wear supporting tights or well-padded socks. Supporting stockings are especially importing for workers with tendency towards venous insufficiency. Thick well-padded socks are useful if you experience heel pain while standing.

Report any problems

If you have any problems with standing work you should report them to your employer. If you have a medical condition that makes it difficult for you to stand for periods of time, you should tell your employer about this and discuss what accommodations could be made to your work.

Examples of interventions

Some examples of specific sectoral approaches are given below.

• Airport security personnel: In order to prevent MSDs and fatigue among airport security personnel following measures^[37] proved to be most effective:
  • Standing support (80% of the security guards found this to be a good solution)
  • Anti-fatigue mats
  • Task rotation (alternating every 15 minutes between: welcoming passengers (standing on a mat or using a stool), screen work (seated) , x ray (standing on a mat), checking bags (standing on a mat), body search (being mobile))

• Checklist for daily practice in the agricultural and green sectors. The Dutch agricultural and green sectors provide a checklist with reminders for workers before they start a task involving prolonged standing^[38]. This checklist should be printed and placed within view from workstations to remind employees on a daily basis, similar to ‘last minute risk analysis’ tools. The daily checklist for working while standing up consists of:
  • Before you start working: organise your workstation
  • Use a stool of an anti-fatigue mat
  • Alternate between tasks
  • Wear comfortable shoes that provide support
  • Work in an active working position

• Packaging, handling and sorting fruit and vegetables. In New Zealand a plug&play 14 page booklet is provided containing basics for workstation ergonomics, how to move on the job and helpful exercises on the job are shown. Each page is an instruction leaflet and a poster at the same time^[39]
• Recommendations for working while standing for Spanish metalworkers^[40]. This Spanish example describes practical tips for healthily working while standing, in short:
  • Adjust the height of the task to the type/level of exertion
  • Alternate your posture to facilitate movement
  • Use a separate or integrated footrest
  • Change the position of your feet to divide the weight of the load
• A healthy hairdresser uses a saddle seat stool on wheels instead of standing up all day. The demands that the hairdresser's saddle seat must meet are^[41]
  • Use a seat in the form of a bicycle saddle or pony saddle
  • The saddle seat can also be used as a standing support
  • The saddle seat is not equipped with a backrest, unless it stimulates an active position (a dynamic backrest)
  • The seat adjustment range is at least 60 to 80 cm above the floor. In specific situations, a customized tailor-made hairdresser's saddle seat (with a different setting range) may be necessary
  • The seat can be rotated relative to the frame
  • When mounted on the floor behind the customers pump seat, the hairdresser's seat must be rotatable in both directions at an angle of at least 135 degrees around the pump seat