1 of 22

�OFFICE�ERGONOMICS

UKY-OccHealth&Safety-OfficeErgo

2 of 22

ERGONOMICS

Creating a better fit between the worker & work environment

UKY-OccHealth&Safety-OfficeErgo

WORKER

ENVIRONMENT

▪Ergonomics is the science and study of work, work methods and the influence’s that the work environment has on job performance. Application of ergonomic principles in the design of the workplace can improve a work environment’s safety, productivity and efficiency. The Ergonomist provides on-site and virtual work site analyses. Recommendations made during such evaluations may improve working comfort and efficiency. Workforce training on office ergonomics is available, and Employees are encouraged-when offered- to attend a basic training on office ergonomics.

▪For help with the ergonomics of your home or university office work setting contact Occupational Health & Safety.

Marty Dagostino MS CPE

Ergonomist

University of Kentucky

Occupational Health & Safety

252 E Maxwell St.

Lexington, KY 40508

859-257-5010

mda402@uky.edu

3 of 22

WORKING RECRUITMENTS

UKY-OccHealth&Safety-OfficeErgo

4 of 22

OFFICE ERGONOMICS EFFICIENCY

UKY-OccHealth&Safety-OfficeErgo

▪CHAIR

EXERCISE BALL SITTING

▪ WORKTABLE

SIT STAND APPLICATIONS

▪ KEYBOARD

KEYBOARD TRAYS

SPLIT KB’s (ERGONOMIC)

▪ MOUSE

ALTERNATIVE POINTING DEVICES

▪ MONITOR(S)

▪ DOCUMENTS/LOCATION

▪ LIGHTING & LEVEL

▪ BIOMECHANICS & STRETCHING

▪Organize the workstations and the elements within so that measurably efficient alignments are recruited like those seen being used by the worker at the far right of this slide.

▪In general, the level of input devices should dictate lowered shoulder recruitments in which arms are in contact with the body and forearms intersect upper arms at 90°. Wrists should be aligned straight/neutral and the reach distance to the pointing device reduced.

▪When seated for long periods, maintain complete foot floor contact with back to backrest support. If the chair provides lumbar adjustment, beltline position this support. Armrests should be easy to raise, lower, and pivot toward and away from our sides. They should also be comfortably padded and rounded at outer margins. For maximum comfort, adjust armrests so that forearm support is secured and so that neutral upper extremity alignments- depicted in this slide- are recruited. Take time to understand your chair and become familiar with the adjustments provided. Most reputable chair manufacturers have websites that link to how to adjust videos.

5 of 22

THE CHAIR & SITTING

UKY-OccHealth&Safety-OfficeErgo

+CHAIR

☑

It has been suggested that the average person spends 80% of each day sitting or almost 13 of the day’s remaining 16 non-sleeping hours. If we dissect these two activities into years spent during a 72-year lifespan, it equates to 24 years spent sleeping and positioned horizontally- and 38 of our 72 years spent seated12 .

▪ Stability Ball Versus Office Chair: Comparison of Muscle Activation & Lumbar Spine Posture during Prolonged Sitting.

Human Factors & Ergonomics Society, Vol 48, Number 1, Spring 2006

▪ Should We Be More on the Ball? The Efficacy of Accommodation Training on Lumbar Spine Posture, Muscle Activity and Perceived Discomfort During Stability Ball Sitting

Human Factors & Ergonomics Society, Vol 55 No. 6, December 2013, pp. 1064-1076

▪ The average US adult sits 6.5 hours a day 1 hour more daily than in 2007.

JAMA 321:1587, 2019

▪ In 2009 the Consumer Product Safety Commission (CSPC) recalled nearly 3 million exercise balls after overinflated balls were reported to unexpectedly burst while in use causing user falls and injuries.

▪ Recommended Office Chair = Steelcase Leap or Gesture

http:www.steelcase.com

6 of 22

KEYBOARD & POINTING DEVICE

ERGONOMIC ?
ROLLER MOUSE

UKY-OccHealth&Safety-OfficeErgo

TRACKBALLS?

☑

Trackballs are inverted-still peripherally situated- pointing devices that require both reaching and grasping and therefore introduce modest deviations in the positional requirements that are arguably the most regionally health aggravating to the mouse end user. Empirical evidence that supports benefits resulting from trackball and ergonomic keyboard use is flimsy. The benefits of trackball and ergonomic keyboard use could likely be characterized as placebo in nature.

The split keyboard design favors resting arm- abducted- alignments common to heavier individuals. Anecdotal observation- Ergonomic Solutions

The Roller Mouse- seen in the middle of this slide- centers and consolidates pointing device work recruitments to the midline while eliminating pointing device reaching and grasping.

Average task completion for 5^th trial on the chord, contoured split, Dvorak and split-fixed angle keyboards were 346, 69, 181 and 42 s, respectively versus 40 s for a conventional QWERTY keyboard. HFES Vol. 51 No.1 February 2009.
The effect of an Alternative keyboard on musculoskeletal discomfort: A randomized cross-over trial. Work 50 (2015) 677-686

The QWERTY keyboard, named for the left most 6 letters in our keyboards upper row, was developed in 1873 as an antidote to typing speed and efficiency. Apparently, early keyboard design flaws caused keys to stick when the simultaneous striking of adjacent keys was performed in speedy succession. The scattered layout of keys as we know it today was employed nearly a century and a half ago to reduce speed and to compensate for machine operational failures.

Improvements in keyboard layout have evolved and trials with alternate arrangements were conducted in 1932 that conclusive demonstrated overwhelming improvements in typing speed and efficiency. However, by this time, so entrenched was the QWERTY keyboard that efforts to introduce keyboards of a more efficient layout were summarily squashed. Guns, Germs & Steel- Jared Diamond-1997

7 of 22

REACHING- INEFFICIENT PRACTICE

Less Strength More Fatigue
Undesirable SHOULDER FLEXION
Keep work close

UKY-OccHealth&Safety-OfficeErgo

∙ Our bodies are remarkably flexible and resilient. However, not all positions are created equal and the approach seen in this slide must clearly be placed in the inefficient column.

∙ If seated please leave the chair and stand.

∙Place your arms near your side and raise the forearms and hands into the efficient alignments described earlier. Pay attention to how your upper extremity and back feel.

Now reach out as if you were the worker in this slide.
Pay attention and note any upper extremity, neck and back differences relative to the arms near one’s side positioning.

∙ Feel the difference?

∙ You should have felt a noticeable increase in tension throughout some or all these areas when you reached forward.

∙ The reason: while reaching is permissible/normal the muscular work to support that seven-pound appendage and in a reaching alignment is considerable. Tension experienced is due to a marked elevation in muscular activity and the probable onset of regional fatigue. The regional work associated with the depicted alignments is measurable and biomechanically inefficient yielding a less for more phenomena- less strength potential with more muscular activity. Continued to chronic positional recruitment- even though output is low- can lead to a cycle of inadequate regional rest/recovery and elevated injury susceptibility.

∙ Keep work close and organize the keyboard and mouse so that their locations encourage the positioning of the arms near the body so that the forearms intersect the upper arms at right angles and so the shoulders are lowered and relaxed.

∙ Finally, remember to keep the area under your desk clear. Accumulating materials may push you further from your primary duties and dictate inefficient reaching.

8 of 22

AVOID THE REACH

UKY-OccHealth&Safety-OfficeErgo

Human Plumb Line

A sagitally traversing- imaginary- line that runs from the top center of the head through the feet.

A demarcation of postural efficiency, it is achieved when our ears, shoulders, hips, knees, and ankles align along this line. If sitting efficiently, body weight is largely distributed through the pelvis and the chair’s seat pan. Additional seated weight distribution occurs when chair backrest support is secured. Backrest use during extended sitting is strongly recommended.

At left, a common keyboard recruitment in which upper body weight has shifted anteriorly, (forward), and beyond this imaginary line. Here, backrest participation in body weight support has been lost and this shift beyond the plumb line yields a near total consolidation of upper body weight bearing to the shoulders and arms.

Also lost here is the spine’s lumbar lordosis, the low back’s natural concave curve. Chronic seated exposure to this alignment undesirably elevates low back forces with poor short- and long- term back health outcomes.

Accommodating this beyond the plumb line weight shift, the shoulders are inefficiently flexed to nearly 90 degrees- allowing near full arm extension and corresponding trunk perpendicularity. Here as well the tabletop is undesirably deployed to support the upper extremities. This recruitment pattern results in bilateral arm/hand “contact stress.” Work environment contact stress is a recognized musculoskeletal disorder risk factor.

Regular to repeated exposure to this position will likely contribute to acute back, neck, shoulder, arm, hand and wrist discomfort and with chronic exposure the risk for musculoskeletal disorder development.

PLUMB LINE

9 of 22

KEYBOARD TRAYS-KBT

UKY-OccHealth&Safety-OfficeErgo

▫Easy install

▫ Retractable- height & tilt

▫ Accommodates Alternative Keyboards

▫ Left & Right Mouse

▫ SAME Level KB & MOUSE

10 of 22

AVOID CONTACT STRESS

Sustained contact with workstation components may contribute to regional irritations and injury
AVOID
Hand/Wrist contact
Arm/Elbow contact
Knee/ Leg contact

UKY-OccHealth&Safety-OfficeErgo

11 of 22

SUPPORTS

May Eliminate undesirable hand/wrist Contact Stress
Desirable Design= Rounded Front
✓ Gel Pads

UKY-OccHealth&Safety-OfficeErgo

12 of 22

WRIST CONSTRICTORS

AVOID- WEARING WRIST BANDS & BRACES DURING WORK
WRIST BRACES INCREASE REGIONAL MUSCULAR & CIRCULATORY RESISTANCE
MUSCULAR & CIRCULATORY DEMAND ANTITHETICAL TO WORKING FINGERS & HANDS
NOT OSHA RECOGNIZED AS PPE

UKY-OccHealth&Safety-OfficeErgo

Avoid workplace use of hard wrist braces

The hard brace is typically five to nine inches in length and encloses the wrist and may extend midway up the forearm. Velcro is a popular securing closure, although combinations of Velcro and other devices are often employed to ensure a snug fit. The critical feature that separates a hard brace from a soft one is the rigid material inserted into its anterior portion (segment that contacts the palmar side of the forearm). Some models have rigidity built into their extensor (dorsal) side as well.

In many hard braces, the rigid support that passes into the palm inhibits formation of a closed fist. Due to this design feature, grasping activities are transferred away from the full hand to the fingers, which produces a less-efficient grip and increases the potential for local fatigue and further irritation. Problems also arise when the wearer must operate a hand tool or manipulate pliers-type implements. In such situations, grasping the tool’s handle can cause the rigid support to compress against the palm. Sustained or routine pressure or impact to the palm should be avoided by those suspected to have or who are diagnosed with carpal tunnel syndrome, CTS.

Bottom line: For the working hand, neither the soft or hard brace is designed to favorably influence regional physiology or biomechanics. In fact, such devices have features that may aggravate an existing injury. The wrist brace can make its greatest contribution to the hand and wrist musculoskeletal disorder healing process when worn during sleep.

A Laboratory Study of Wrist Splint Orthoses on Forearm Muscle Activity & Upper Extremity Posture. The Journal of Human Factors & Ergonomics Society, Volume 48, Number 1, Fall 2006

13 of 22

MONITORS

Central to seated location
Top of the screen at eye and nose level
Viewing distance- arms length away
Bifocal wearers 🡪 lower
Consider Monitor Arm introduction

UKY-OccHealth&Safety-OfficeErgo

14 of 22

DISPLAY

UKY-OccHealth&Safety-OfficeErgo

SCREENS

DISTANCE ARMS LENGTH AWAY

SCREEN TOP EYE TO NOSE LEVEL

LOSS OF EQUIDISTANT VIEWING

LAPTOP SCREEN?

The principal display(s) in the computer work environment should be situated directly in front of the seated position and at a distance- from the eyes- of 20-30". This equates to a reach of about arms length away. If one can just about reach and touch their display(s) the viewing distance is correct. As for display height, the top of the screen should align between eyebrow and nose level. Both distance and eye level recommendations do not change when alternating to standing work. With twin displays , the screens should be situated side by side, at the same height and in an inverted V -configuration. This organization yields an eye friendly common viewing distance. If using dual displays, matching screen size insures character size compatibility. Use of different sized screens undoubtedly results in character size disparities, and such an arrangement elevates focusing requirements. When feasible, deploy screens of the same size.

LARGER DISPLAY-If you are an older worker, have noticed declining visual performance- and or have been diagnosed with eyesight deficiencies- upgrading to a larger display(s) should prove helpful. In general, as screen size increases, so does character size and a larger font is easier to see.

CLEAN SCREEN- Most electrical appliances- and computers- emit both ionizing and non-ionizing radiation.

Emissions from computer screens are so low as to be nearly un-measurable and fall far below levels designated as creating a safety risk exposure. In fact, the overwhelming empirical evidence on this topic has failed to link the emissions from computer screens to any health problem, including those for the eyes. While not technically a form of radiation, the area surrounding computers screens develops an electrostatic charge, which attracts environmental dust. Regularly, cleaning computer screens removes these accumulates and promotes enhanced screen visibility.

15 of 22

WORKTABLE HEIGHT-ADA RECOMMENDED

≥ 30” W X 48”L
KNEE CLEARANCE ≥ 27”H & ≥ 30”W
LEG CLEARANCE

≥ 17” BUT ≤ 25”

▪ 29- 30” H & SEATED WORK TOO HIGH FOR MOST

▪ ADA MINIMUMS

UKY-OccHealth&Safety-OfficeErgo

INDUSTRY STANDARD TABLE HEIGHT= 29-30”

▪ The height of a workstation’s keyboard and mouse are as important an office ergonomics work variable as exists. In general, the level of input devices should dictate lowered shoulder recruitments in which arms are in contact with the body and forearms intersect upper arms at 90°. Wrists should be aligned straight/neutral and the reach distance to the pointing device reduced.

▪ Unsure what is the right seated or standing tabletop height for your computer duties? Contact Occupational Health & Safety for a best fit FOR YOU tabletop height.

∙ center keyboard 

∙ hands neutral on kb 

∙ mouse next to kb 

∙ mouse at same level as kb 

∙ pad table edges & reduce contact stress

∙ roller mouse 

▪ While the height of the keyboard, pointing device and screens rise during standing office work, the neutral upper extremity alignments recruited during seated work should not. That said, many find a slightly lower standing KB height and one that dictates the so-called “negative-tilt” of the hands and wrists preferable. Experiment with different standing levels to find the best feel.

16 of 22

TO STAND- OR NOT TO STAND?

More Demanding?
Plop on Top?
SEATED LEVEL?
STANDING LEVEL?
How Much Standing?

UKY-OccHealth&Safety-OfficeErgo

3 LIFT COLUMN-EXTENDED LEG HEIGHT ADJUSTABLE TABLE

▪ If you have questions- or would like a product recommendation on the right for you adjustable height application-for home office or university work setting- contact Occupational Health & Safety

▪ Comparison of Sedentary Behaviors in Office Workers Using Sit-Stand Tables With and Without Semiautomated Position Changes-HUMAN FACTORS Vol. 59, No. 5, August 2017, pp. 782–795

▪ Both groups were, on average, sitting for 85% of the workday

▪ Differences of energy expenditure while sitting versus standing: A systematic review and meta-analysis-European Journal of Preventative Cardiology- January 31, 2018

“Ergonomic” applications were reviewed. One study compared standing and in sitting office workers performing the same task and during a six-hour period. The results revealed the standing group burned 54 more calories than the seated group during the six-hour period. This reported greater standing metabolic output roughly covers the calorie intake of a single Kit Kat Bar wafer.

▪ Muscular and Vascular Issues Induced by Prolonged Standing With Different Work–Rest Cycles With Active or Passive Breaks- HUMAN FACTORS Vol. 60, No. 6, September 2018, pp. 806–821

Muscle fatigue, vascular outcomes, and performance were affected by 5 hours of prolonged standing work regardless of the work–rest cycle or break type. Three hours of standing work showed a detrimental effect in terms of muscle fatigue but not performance. Subjective perception of discomfort does not reflect long-lasting fatigue. Alterations of the work–rest cycle may not be a sufficiently efficient solution for mainly static standing work, and an active break type does not have an advantage over a passive break type during work.

▪ Musculoskeletal & Cognitive Effects of Movement During Prolonged Standing Office Work

HUMAN FACTORS Vol. 60, No. 7, November 2018, pp. 947–961

Discomfort increased significantly over time across all body regions. Ankle/foot differed between conditions, with higher discomfort during standing with movement. Creative problem-solving errors increased during standing. Standing with movement by using a footrest provided no advantage in discomfort or cognitive function and even some negative effects on discomfort at ankle/foot and creative problem solving.

Late in 2024 and early 2025- two scientific papers were published with both assessing outcomes from standing office work exposures. One evaluated the circulatory system response to static standing office work. Data from 80,000+ participants was collected. This study suggested that exposure to standing office work could result in undesirable, possibly permanent, changes in lower extremity circulatory anatomy¹. The other evaluated standing work exposures on blood pressure in which the finding was that idle standing exposures led to above normal 24-hour blood pressure outcomes; a study result not observed in seated participants¹⁵.

17 of 22

FOOT & HEADRESTS + EXTRA PADDING

INNUMERABLE CONFIGURATIONS
☑ FOOTREST INTRODUCTION IF SEATED & FEET ARE NOT FLAT ON FLOOR
MOST ANGLE FEET IN CAR GAS PEDAL DORSIFLEXION
MODEST BENEFIT- AT BEST

UKY-OccHealth&Safety-OfficeErgo

FLOOR MATS

DIMINISHING REGIONAL TACTILE FEEDBACK & ELEVATED LOWER EXTREMITY INSENSIBLE MUSCLE ACTIVITY

▪ If in one’s home recliner-with the feet elevated-the headrest is a great feature,

providing the support nestles into the neck’s natural concavity -cervical curve.

▪ An automobile's headrest is essentially a safety feature and not engineered with comfort as priority one.

▪ Pretend you are at a car’s steering wheel.

Tilt the head back to the headrest and now simulate reaching for the steering wheel.

How does that feel?

What do you feel?

▪ For those working with computers and performing entry

duties, interactions with the mouse and KB typically dictate upper extremity movements away from the trunk and these motions are largely antagonistic- (opposite)- to the movement, or positioning, of the head against a chair's headrest.

▪ Earlier we discussed the body's plumb line.

Maintaining balanced work recruitments assists in promoting near plumb line weight distributions, desirable. Extending the arms with the head pressed against a chair's headrest yields- undesirable and inefficient- east and west plumb line recruitments/deviations.

▪Long-Lasting Changes in Muscle Twitch Force- (MTF)- During Simulated Work While Standing or Walking- Human Factors, Volume 58 Number 8, December 2016, pp.1117-1127

▪ Headrests became a standard automobile manufacturing requirement for new US passenger cars on January 1, 1969. The Federal Motor Vehicle Safety Standard- 202- established this design requirement as a measure to reduce injury outcomes resulting from rear-end collisions.

18 of 22

EYE CARE

Lighting & Glare

UKY-OccHealth&Safety-OfficeErgo

ENVIRONMENTAL COLOR UNIFORMITY
VIEWING DISTANCE UNIFORMITY
CHARACTER SIZE UNIFORMITY
ILLUMINATION LEVEL UNIFORMITY
DISPLAY COLOR UNIFORMITY

The Illumination Engineering Society of North America (IES) has established lighting standards for most work locations. In an office environment, particularly one in which computer work or viewing is continuously performed; a dimly lit workplace is suggested.

Blue light is part of the visible light spectrum – that which the human eye can see. It has the shortest wavelength and highest energy. About one-third of all visible light is considered high-energy visible, or "blue," light. Sunlight is the most significant source of blue light. Artificial sources of blue light include: fluorescent light; compact fluorescent light; LEDs; flat screen televisions; computer monitors; smart phones and tablet screens. Blue light boosts alertness, helps memory and cognitive function, and elevates mood and regulates the body's natural wake and sleep cycles. Sunlight is also important for the growth and development of the eye and vision in children. Inadequate exposure to blue light has been suggested to be the link to a recent worldwide increase in myopia- (nearsightedness) - particularly in youngsters. Researchers discovered that children spending the greatest time outdoors had a markedly reduced risk for developing myopia. The studies are suggesting that blue light from sunshine helps stimulate normal eye formation and inadequate blue light from the sun may be under-stimulating the growth of young eyes.

BLUE LIGHT GLASSES- Since the eye is not good at blocking blue light, nearly all visible blue light passes through the transparent eye- (cornea and lens)- and reaches the retina. Chronic exposure to blue light may lead to retinal cell damage and vision problems. A consensus opinion is that abundant blue light exposure before bedtime disrupts sleep. It is also understood that the blue light emitted by computer screens and hand-held devices is less tame than light of longer wavelengths and is probably tougher on our eyes. What is not clear- excuse the pun- is whether blue light blocking glasses protect the eye from blue light. In at least one study, blue light glass wearing reduced contrast and perception of speed and the authors concluded if worn while driving could increase the risk for inadequate speed correction and an accident. Depending on the quality, blue light glasses reduce exposure by 6-43% with the mechanism for how this accomplished not regulated. While there are many studies on blue light glasses, there isn’t a consensus on their value.

19 of 22

WINDOWS & GLARE

UKY-OccHealth&Safety-OfficeErgo

WINDOW

DIRECT GLARE

WINDOW

INDIRECT GLARE

RECOMMENDED

WINDOW

20 of 22

THE HOME OFFICE

UKY-OccHealth&Safety-OfficeErgo

21 of 22

WORK METHODS

Rest Breaks & Mini-Breaks (20-20 RULE)
Change Positions
Change Tasks
Stand & Work
Keyboard shortcuts

UKY-OccHealth&Safety-OfficeErgo

▪ Alternate tasks: vary task performance and alignments during the workday.

▪ Use macros or keyboard shortcuts as a measure to reduce mouse usage.

Find keyboard shortcuts

1.In any word document choose View>Macros>Macros from the menu

2. In the Macros in: drop down choose word commands

3. In the Macro name field scroll to & select list commands

4. Click on Run. The list commands dialog box will appear & select All Word Commands

5. A list of KB short-cuts will appear

Examples: CTRL+X=Cut- CTRL+C=Copy- CTRL+Z=undo- CTRL+S=Save- CTRL+V=Paste

▪ Work/Rest intervals for Computer Users

The National Institute for Occupational Safety and Health (NIOSH) recommends a 15-minute rest break after 2 hours of continuous computer screen viewing for operators under moderate visual demands and a 15-minute rest break after 1 hour of computer screen viewing when visual demands or repetitiveness of tasks are high.

22 of 22

USE IT IN GOOD HEALTH!

UKY-OccHealth&Safety-OfficeErgo