Ergonomic risks in and standing workplaces

Dr. Igor Grabovac Department of Social and Preventive Medicine Center for Public Health Medical University of Vienna 58% of the population over the age of 10 spends 1/3 of their life at the workplace.

Only 5-10% of workers in developing countries and 20- 50% of those in industrialized countries have access to occupational medicine and safety services. Public health aspects • In Europe: • 33% of all workers are exposed to tiring or painful positions • 46% exposed to repetitive hand and arm movements • 31% are working in front of the computer for at least half of their working time • 34% have access to ergonomic counseling • 33% european workers claim that their job tasks influence their expeirence of

• MSD: • Multifactorial • Prevalence on the raise • Among top 10 reasons that account for the highest number of DALYs • Costs assocaited range in hundrets of billions of US dollars Neutral position

• Gravitational influence forces all parts of the body downwards

• Parts of the body that are in contact with supporting structures (seats, floor, etc) will put pressure on these structures to balance this force

• Parts of the body not in contact with supporting structures will use muscles to balance the gravitational pull

Neutral position is: The body position that has the highest strenght to handle the pressure felt by supporting structures while causing the least amount of strain on the muscles Sitting workplaces - Overview

• One of the oldest ergonomic concerns

• Chair design and seating are not only related to ergonomic aspects but also by sitter safety and productivity

• Biomechanical aspects rarely reported in literature

• One of the most common working positions (wide variety of professions)

Sitting workplaces – Consequences

• Poor sitting is associated with health risks, discomfort and accidents • Most widely recognized health issue arising from poor sitting are musculosceletal disorders (MSD)

Back pain: Other factors contributing to MSD:

• load to the spine • highly frequent movements • spinal posture • postures deviating from the • degree of lumbar neutral position • positions held for long periods Sitting workplaces – Consequences

Sitting requires a fixed position of the Sitting on the edge of a chair creates neck, trunk, head and shoulders in a pressure to the popliteal region, which: fixed position, this: • Squeezes the blood vessels in the • Reduces the venous blood flow mussles • Increases the blood pressure in • Reduces the blood flow and the legs oxygen supply when muscles are • Creates swelling of the feet and in an isokynetic contraction legs • As a result: accelerates fatigue and • Can contribute to thrombosis and makes muscles prone to injury varicose venes

Long periods of sitting poses strain on the cardiovascular system Sitting workplaces – Consequences

Additionally:

• Sitting posture decreases the space in the trunk and increases the pressure on internal organs

• Has an influence on decreased oxygen uptake

• Is associated with stomach issues and colon cancer

• Discomfort makes leads to compensatroy activities and creates distraction fromt he main task

Sitting workplaces – Posture

Poor posture can also originate from Being constrained into an poor job design and the physical awkward position with no arrangement of work space elements relief or possibility to (tools, surfaces, equiptment, etc) change causes most MSD

Limited mobility and localised tension (usually neck and lower back): • Reduces movement and may cause muscles to strain, cramp or pull • Causes tension in the body • Causes on compression of interverterbral disks Posture is influenced by contributing to movement ability and climate degeneration What makes a good sitting position?

A good sitting Sitting work is Visual tasks create position does not dynamic (visual, tension on the neck, impede a persons‘ manual and foot trunk and pelvis  breathing or tasks in workplace needs to be circulation combinations are designed to reduce the often required) strain  if not possible; workers need to spend less time on each task The arrangement of the workplace needs to allow If workers use the workers to keep their pedals these need Sitting workplaces need spine vertica  No lifting to be infront to allow the worker to or horzontal punshing of directly to prevent frequently change loads in the sitting hip twisting position between a variety of body positions !! Sitting workplaces – maintaining a neutral position

Back is supported when Head is leveled or slightly bent facing forward upright or bent backwards Relaxed shoulders with the arms hanging beside the body Supported tighs and hips and parallel to the floor

Elbows close bent between 90 and 120 degrees

Knees at hip Erect and upright spine height No twisting of the upper torso Hands, wrists and forearms straight, parallel to the floor Feet fully supported Sitting workplaces – chair

Basic ergonomic rule: no NO CHAIR FITS ALL! such thing as an „average“ person  providing a To be avoided: specially designed chair to every employee is  Tilting head impractical: forward  Solution is to offer fully  Sitting without adjustable chairs that lumbar support accomodate 95% of the  Working with populous raised arms  Chair has to allow  Bending wrists adjustability of height  Unsupported and tilt as well as forearms backrest hight and angle  Trial period is recommended Sitting in a too high high chair:

 Destabilization of the body leading to tiredness  Puts pressure on the tighs increasing pressure in the legs and feet  Pressure on the sciatic nerve causing pain and discomfort  Inappropriate lumbar support Sitting in a too low chair:

 Disrupts lower leg circulation leading to swelling  Exessive pressure to the internal organs  Breathing problems  Exessive pressure on the buttocks causes discomfort Disc pressure normalized to standing (percent) Sitting workplaces – manual tasks • All seated tasks need to be designed to maintain the vertical spine allignment and avoid stress of the shoulders • Provide materials slightly below elbow height • Provide arm rests when appropriate (eg. Moving the chair) • Avoid heavy hand tools • Avoid the need for excessive reach Standing work - overview

Standing position is preffered over seating Standing posture is usually found in: when:

• Job taks cannot be preformed with the • Assembly work, packaging and employees keeping their hand at the side painting lines • The work area ist too large to be • Welding and sheet metal comfortably reached production • The worker works in more than one area • Kitchens and gastronomy • The work surface does not allow to rest • Health care the legs comfortably under the surface • Maitenence, inspectors without obstruction • Firefighters • Working at the counter or with a drawer located underneath the working surface

Standing work - posture

Standing work is not really static

• Erect people are unstable, constantly swaying • People adopt asymmetrical standing positions 4 times more often as symetrical • Shifting the weight between feet is a relief mechanism • People often stand with one foot forward for more stability • Standing people constantly sway anterior- posterior and lateral – compensatory muscle activity is often necessary.

Standing work – health concerns Venous pooling as a result of prolonged standing:

• Creates more exerction for the heart (increasing the HR) • Mean venous pressure was found at 87 mm during standing (opposed to 56 mm for sitting) • Causes edema, swelling and varicose venes • Walking drops the pressure at the ankle level to around 20 mm after only 10 steps • 2-4 min of walking for every 15 min of standing work is more comfortable • Body sway influences the blood flow in the feet • Standing work is associated with increased hospitalizations and carotid atherosclerosis and ischemic heart disease

• Additional health problems by standing work: • Sore feet • General muscular fatigue • • Stiffness of the neck and shoulders

• Excessive standing may cause the large joints in the body to be temporarily immobilized and locked – this may lead to degenerative damage as well as rheumatic diseases Standing work – footrests • Footrests can reduce interverterbral disc stress by preventig exessive

• Studies showed that workers used foot rest options significantly more when given the option • In a study that investigated the difference in use of a bar, flat platform or a platform with an 15 degree angle: the paltforms were used more often than a bar (59% vs 80%) Standing work – floormats • Floormats are designed to allow for the antural sway of the body and to encourge the subtle movements • Research supports the notion that floormats are preffered over concrete floors for stnading work • In a study that compared the comfort of work on a hard wood floor with standing on a floor mat, wearing shoes with insoles and a combination found that insoles and mats were more comfortable than standing on a hard wood block floor. • However, no difference found between insoles and floormats • Too much cushioning needs to be avoided • Floors need to be clean and non slippery Standing work – shoes Recommendations:

• Do not wear shoes that change the shape of the feet • Shoes need to mold to the feet and cause minimum pressure • Due to feet swelling half-size larger shoes should be used • Shoes that allow movement or the toes should be used • Shoes need to have arch support • Firm grip on the heel is necessary to prevent the foot to slip • Flat shoes or shoes with a high heel should be avoided • Heels should be wide base between 2 and 2.5 cm high Standing work – workplace considerations

• The worker should have the opportunity to change between positions – this involves more muscles and provides a better distribution of loads

• Working tables and benches need to be adjustable

• If the worksurface cannot be adjusted than platforms for shorter workers or pedestals on top of the surface for tall workers need to be implemented

• Organization of the workplace needs to minimise the need for bending or twisting and there should be enough room to move

• Where possible a seat should be provided for the workers to sit occasionally

Standing work – workplace considerations

• Different tasks require different work surface heights • Precision work – cca 5 cm above elbow height • Light work – cca 5-10 cm below elbow height • Heavy work – 20-40 cm below elbow height

Workers should avoid:

• Reaching behind shoulder line • Overreaching • Reaching above the shoulder line Standing work – rest • Breaks are important to reduce the incidence of MSD • Rate of recovery is not constant, in standing it is exponential • Short breaks with shorter work periods have been found more beneficial as more recovery was accomplished • Leg swelling recovery is a longer process where breaks of 15 minutes were found necessary – sitting does not help • In order to reduce MSD: • Cumulative load needs to be reduced • Variation in body positioning is necessary • Provide sufficient recovery time Standing vs Sitting work

• Static work positions, sitting or standing are not recommended

• Workers need to be provided with a station and a job task that allows the employee to change posture and switch between standing, sitting and walking Sitting and Standing workplaces – evaluation

1) Loadings: 3) Comfort : • Interverterbral disk pressure • Ratings of discomfort, exerction • EMG • Pain and disorders • Gravital load • Pleasure • Intraabdominal pressure • Preferences • Blood pressure and flow Performance: 2) Posture: • Work speed • Spinal curvature • Errors • Range of motion Implementation of Ergonomic Solutions • Example: weighing ingridients in the food industry

• 67% of the total working time is done in an unfavorable position • Solution: rasing of the electronic scale • Total costs: 145 Euros Implementation of Ergonomic Solutions • Example: Transfering load in a packing facility

• 3451 N of force at the L5/S1, exceeding the maximum • Solution: raising the palets or a mechanical vacuum transfer system • Price: 450 Euros or 6000 Euros Implementation of Ergonomic Solutions • Example: Strawberry farm problem

• 3,5 acers greenhouse

• Strawberries are grown on raised platforms

• Current solution: stilts

Implementation of Ergonomic Solutions • Example: Strawberry farm problem • Stilts are problematic: • Move the center of gravity for more than 30 cm • Contribute to lower back stifness and pain • Present a serious hazard

Solution?

Special workplaces: Nursing

• Nursing staff has one of the highest rates of reported back pain • In the USA 52% of nurses complain of chronic back pain • 12% are changing their profession due to pain • 38% had time off for therapy due to back pain

• One of the major issues: transferring patients

Occupational Risks in Nursing

INEFFECTIVE, MANUAL TRANSFER HIGHLY STRESSFUL, TECHNIQUES UNSAFE AND UNCOMFORTABLE

 Loading forces up to 4800 N

 98% of all transfers still done manually

 Leads to high absenteeism, low productivity and low patient satisfaction due to inconsistency of health care workers involved Ergonomic Aids

 Effective and accessible  High cost

Education & Job Design

Refusal to use mechanic aids:

 Common problems identified by the researchers were lack of proper training in mechanical aid use, mechanical aids and slings being unavailable or inaccessible, arbitrary use of mechanical aids and spatial constraints to mechanical aid use.

 Student nurses were frequently unable to use recommended techniques in practice. The most frequent explanation given was the influence of other nurses. Results that male students and younger students were more susceptible to socialization into poor ward practice than others. © Štefanac S, Grabovac I, Karabatid S: “Unified Patient Transfer Algorithm”

Contact:

Dr. Igor Grabovac Department of Social and Preventive Medicine Center for Public Health Medical University of Vienna [email protected] References

Canadian Centre for Occupational Health and Safety. Working in a Standing Position – Basic Information: https://www.ccohs.ca/oshanswers/ergonomics/standing/standing_basic.html

Canadian Centre for Occupational Health and Safety. Working in a Sitting Position – Overview: http://www.ccohs.ca/oshanswers/ergonomics/sitting/sitting_overview.html

Salvendy, G. Handbook of Human Factors and Ergonomics. Wiely:UK,2012

Kumar, S. Biomechanics in Ergonomics. Taylor and Francis: UK, 1999.

Grabovac I, Stefanac S, Mustajbegovic J. Unified Algorythm for Safe Patient Transfers: An Ergonomic Solution. Nursing Journal. 2017;22:37-43.

Ebben J. M. Improved Ergonomics for Standing Work. Occup Health Saf. 2003;72(4):72-6.