Describe ergonomics and the work-related musculoskeletal disorders.

Ergonomics and Work-related Musculoskeletal Disorders

• Its scope — the design of tools, equipment, workstations and tasks; the layout of the work area; the physical environment of light, heat and noise; and the organisation of work, including pace, hours and rest breaks
• It draws on anatomy, physiology, psychology and engineering, and anthropometry — the measurement of body dimensions — is its practical foundation
• A practical point about anthropometry deserves emphasis — equipment designed to Western body dimensions does not fit Indian workers, and equipment designed for men does not fit women
• The consequence is real — a bench, a tool handle or a machine control at the wrong height forces a sustained awkward posture, which is precisely what causes musculoskeletal disorder
• Design should generally accommodate the range from about the 5th to the 95th percentile, and adjustability is preferable to a single fixed dimension
• Work-related musculoskeletal disorders are the commonest occupational health problem worldwide by number, and the largest cause of lost working days
• The risk factors, which should be listed since they are what an assessment looks for:
• Force — heavy lifting, pushing, pulling and gripping
• Repetition — the same movement performed many times an hour
• Awkward posture — bending, twisting, stooping, reaching above shoulder height, kneeling and squatting
• Static posture — holding any position for prolonged periods, which is more fatiguing than movement because muscles remain contracted and blood flow is reduced
• Vibration; cold; insufficient recovery time; and psychosocial factors such as high demand with low control, which are independently associated with musculoskeletal symptoms
• The common disorders — low back pain, much the commonest; neck and shoulder pain; carpal tunnel syndrome; tenosynovitis and DE quervain tenosynovitis; epicondylitis (tennis and golfer’s elbow); rotator cuff disorders; and osteoarthritis of the knee in those who squat or kneel
• Manual handling and the correct technique — assess the load and the route first; get close to the load; adopt a stable base with feet apart; bend the knees and keep the back straight; keep the load close to the body; avoid twisting while carrying; lift smoothly without jerking; and get help or use equipment for heavy loads
• A caution should be given about training in lifting technique — the evidence that training alone prevents back injury is weak
• What works better is eliminating or reducing the manual handling itself — by mechanical aids, trolleys, hoists, reducing package weight, and changing the layout so that loads need not be moved at all
• This is the hierarchy of control applied to ergonomics, and it is why a poster about lifting technique is the ergonomic equivalent of personal protective equipment
• Display screen and office work — the top of the screen at or just below eye level; the screen at about arm’s length; elbows at roughly 90 degrees with forearms supported; wrists neutral; feet flat on the floor or on a footrest; lumbar support; and the document holder at the same level as the screen
• The single most important measure is not the furniture but the breaks — short, frequent changes of posture and brief pauses are more effective than long infrequent ones, because the harm comes from the static posture rather than from the activity
• The "20-20-20" rule for eye strain — every 20 minutes look at something 20 feet away for 20 seconds
• Ergonomics in the INDIAN context — agricultural work involving prolonged stooping for transplanting and weeding; head-loading; squatting work in small workshops and home-based industry; hand tools designed without regard to grip or hand size; and the near-total absence of ergonomic consideration in the unorganised sector
• Simple, cheap ergonomic changes can have large effects — raising a work surface to elbow height, providing a stool so a task is done seated rather than squatting, improving a tool handle, or adding a simple wheeled trolley
• The economic argument — ergonomic improvement reduces absence, error and injury while increasing productivity and quality, which is why it is one of the few occupational health measures an employer can be persuaded to adopt on commercial grounds alone
• Fit the job to the worker, which is the whole principle and the source of every other ergonomic rule
• Static posture is more fatiguing than movement, so frequent short breaks beat long infrequent ones
• A lifting poster is the ergonomic equivalent of PPE, being last in the hierarchy rather than first
• Training alone weakly prevents back injury; reducing the handling itself works far better
• Western and male dimensions do not fit Indian workers or women, which is an anthropometric point with real consequences
• Design for the fifth to ninety-fifth percentile, and prefer adjustability to any single fixed dimension
• Low back pain is much the commonest disorder and the largest single cause of lost working days
• Screen top at or just below eye level, at arm length, with forearms supported and wrists neutral
• Every twenty minutes look twenty feet away for twenty seconds, which is the simplest measure against eye strain
• Raising a surface to elbow height helps, and costs almost nothing, which is the character of most ergonomic gains
• Ergonomics raises productivity as well as health, which is why employers adopt it on commercial grounds alone