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The Seasoned Worker: Ergonomic

Aspects of a Productive Aging Workforce

S.M. Jones ~ FutureComp

The Seasoned Worker: Ergonomic Aspects of a Productive Aging Workforce

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U.S. Department of Health & Human Services

Center For Disease Control (2011)

• Older workers (defined as those aged ≥55 years) represented 19% of the United States workforce in 2009 and are the nation’s fastest growing segment of the working population.

Human Factors and Ergonomics

• Human Factors and Ergonomics is the science of designing products, job tasks, systems and environments that fall within an individual’s cognitive and physical abilities.

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The Seasoned Worker: Ergonomic Aspects of a Productive Aging Workforce

• Above the Neck

• Below the Neck

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The Aging Worker • Above the Neck • Below the Neck • Strength • Cognitive ability • Reaction time • Balance • Connective tissue • Hearing • Physiological fatigue • Vision • Heat stress • Musculoskeletal disorders

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Musculoskeletal Disorders

Ergonomic Risk Factors

• It is not typically a single ergonomic risk factor that causes a musculoskeletal disorder, but rather, the magnitude and duration and frequency of exposure to a combination of risk factors.

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Awkward Postures • Awkward postures require

muscles to work inefficient

positions which can result in

fatigue.

• Ask: How “out of neutral” is the

posture?

Awkward Postures

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Sustained Postures

• Sustained or static postures

occur when the same position is

held for an extended period of

time.

Fatigue and Sustained Postures

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Repetition

• Repetition refers to performing tasks or motions over and over again with the same muscle groups with little variation or recovery time. • Many people think of the risk factor repetition as the primary cause of musculoskeletal injuries. • However, repetition is only a single risk factor and rarely causes injury by itself.

Force

• Performing forceful exertions can place high mechanical forces, or loads on muscles, tendons, ligaments, joints and discs of the low back.

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Force vs Repetition

• How much force is too much force? • How many repetitions are too many repetitions?

Muscles Can Only Pull, Not Push • Because muscles can only pull they will always work in pairs. • For example, the forearm extensors contract to pull the hand up, the forearm flexors contract to pull the hand down. • Of the two muscles, one of the muscles is always stronger.

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The Aging Worker and Muscle Flexibility • The aging worker can loose muscle flexibility due to loss of muscle elasticity, increased scar tissue or decreased activity. • The purpose of stretching is to maintain normal motion or improve limited range of motion of a joint. • Stretching can improve flexibility in the aging worker.

The Aging Worker’s Grip Strength

• The loss of hand grip strength in males by age 65 is about 20% compared to the values of 20 year olds. • The loss over the same 45 years for females is from 25 to 20%.

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The Aging Worker’s Muscle Strength • As the human body ages, it loses muscle mass and strength resulting

in less effective abilities or inability to perform routine activities.

• Muscle strength in both men and women peaks around age 30.

• There is an average decline of 16.5% in muscular strength after the third decade of life.

• Between age 50 and 60, most people can produce only about 75% to 85% as much strength.

The Aging Worker’s Muscle Strength

• Physical exercise can delay the decrease in lean body mass and strength.

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Environmental Risk Factors

• Heat • Cold • Hand Arm Vibration • Whole Body Vibration

Thermal Regulation

• The body becomes

less able to maintain internal temperatures as it ages.

• The aging worker can be more susceptible to becoming overheated and suffer from heat stress. • They may also be less able to cope with cold work environments.

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The Aging Worker’s Metabolism

• Basal metabolic rate, which accounts for about 50 to 70 percent of an individuals total energy expenditure decreases about one to two percent per decade. • That is, after a person reaches 20 years old, daily energy expenditure decreases about 150 calories per decade. • The decline is primarily due to decreased muscle mass (which is highly metabolically‐active) and increased fat mass (which is relatively metabolically‐ inactive). • Deceased activity often accompanies these changes as well compounding the effects.

The Aging Worker and Physiological Fatigue

• An average person continues to slowly make new alveoli until about age 20. • After that age, the number of alveoli decreases and the lungs also become less elastic

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Above the Neck Ergonomics

• Nervous System • As people age, the brain and nervous system go through natural changes. • Nerve cells may transmit messages more slowly than in the past. • However, there are many misconceptions about the nature and extent of these changes.

Above the Neck Ergonomics

• A common myth is that all elderly people become senile. • Delirium, dementia, and severe memory loss are NOT a normal processes of aging.

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The Aging Worker’s Cognitive Ability

• Types of Intelligence • Fluid Intelligence

• Related to understanding new, complex relationships and making inferences and conclusions that solve complex problems.

• Crystallized Intelligence • Related to an individuals breadth and depth of knowledge.

• Practical Intelligence • Practical intelligence is a major contributing factor to achieve success in the workplace. • Research has found that Practical Intelligence stabilizes with age in spite of declines in

standard reasoning test performance.

The Aging Worker’s Vision

• Eighty five percent of the information we gather comes through our eyes. Vision includes not only what we can see but how we process that information. • More light is required with age: • 20‐year old requires 1x • 40‐year old requires 2x • 60‐year old requires 5x to 6x

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Awkward Postures and Vision • Vision can directly affect an individuals posture.

• Individuals will often change their posture in order to see what they are working on.

The Aging Worker’s Vision

• Near point vision is the closest point at which a person can focus. • The near point increases with age, from 4” at age 20 to 8.5” at age 40.

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The Aging Worker’s Vision

• Contrast Sensitivity Decreases with age. • When compared to a 20 year old worker: • A 40‐year‐old requires 120% as much time to detect differences. • A 50‐year‐old requires 160% as much time to detect differences. • A 60‐year‐old requires 270% as much time to detect differences.

Age & Road Sign Discriminability

• Although all subjects had 20/20 visual acuity or better, the older group had significantly lower contrast sensitivity than the younger group. • The older group, had to get 24 percent closer to the sign and required a significantly larger sign symbol in order to determine if it denoted a "+" or a "T" intersection.

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The Aging Worker’s Balance

• Roughly 9% of adults who are age 65 and older report having problems with balance. • Falls account for one‐third of all injuries sustained by workers aged 65 and over. • Same level falls account for a significant number of work‐related injuries suffered by older workers. • Falls on stairs, ladders and other elevated platforms are an another risk common to older workers.

The Aging Worker’s Reaction Time

• The cumulative effect of aging on central nervous system function are exhibited by: • A 37% decline in the number of spinal cord axons and a 10% decline in nerve

conduction velocity. • Driver reaction times can be 1.5 seconds slower in an individual over the age

of 65.

• However…........ • Older groups who remained active for 20 years or longer have reaction times

that are equal to or faster than inactive men in their 20s.

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