Chapter 11: Light and Moderate Work

1. Chapter 11: Light and Moderate Work Dr. Katie Cahill Science 295

2. Light and Moderate Work • Basic metabolic functions work the same as with hard labor, but at a lower level • Byproducts dissipated through the skin and respiration • Blood flow is not a limiting factor; the demands require an ability to perform endurance tasks with attention to detail during possibly long shifts • Environment contributes to our perception of work • Psychosocial environment - getting along with co-workers and supervisors • Physics environment – temperature, humidity, noise and lighting, arrangement of working hours (shiftwork)

3. Physiological and psychological principles • Most jobs are sedentary and require little physical effort • Many people with sit-down jobs try to bring up daily expenditures by doing demanding leisure activities to avoid weight gain from unneeded food intake

4. Physiological and psychological principles • Stairs and ramps • Use the stairs instead of the elevator to make up for sedentary day • Energy use depends on step design and stair steepness (Figure 11.2) • Measuring work and load effects • Heart rate is the most useful indicator during light work because it responds to static muscle loading • HR may also respond to emotional excitement, emotions; HR may reflect more than just physical work • Other possible techniques: EMGs, EEGs, eyelid closure frequencies, simple observation

5. Physiological and psychological principles • Scaled judgments • A way to assess satisfaction is to ask for employee opinions • Usually done through questionnaires: • Paired descriptors (p. 218) • Ordinal scales – pain on a scale of 1-10 • Interval scales • Ratio scales – allow for mathematical calculations • Subjective, not objective information • Studies may generate awareness of problems at work, which management may want to avoid

6. Physiological and psychological principles • Nordic questionnaire (figure 11.3) • 2 parts: • General information • Area focused on specific regions of the body -Body is divided into 9 regions and the person indicates where they experience musculoskeletal problems

7. Tiredness, boredom and alertness at work • Tiredness – the state in which we feel unable or disinclined to continue a task • Fatigue – the physiological effect of having spent our energy, or overstrain of our muscles so that our body needs to rest • Boredom – the psychological or emotional condition in which a lack of events lulls us into a state of sluggishness • Bottom line: In everyday life we feel tired as a result of physical fatigue or psychological boredom

8. Tiredness, boredom and alertness at work • Diversity vs. monotony • Monotony - the quality of constancy, routine, and lack of variety • Some individuals enjoy jobs that have diverse parts -challenges mental and physical capabilities -keeps workers interested -Workers find satisfaction in successful solutions • For others, job/task predictability is appealing -find satisfaction in skillful repetition • For most people, performance and job satisfaction is best when the job is not overly simple or overly complex

9. Tiredness, boredom and alertness at work • Vigilance and event frequency • Ability to maintain concentration was found to be very important during WWII • Noticed that the frequency with which radar watchers reported submarines decreased with the longer they watched; alertness decreased with time on watch • Frequency of signals influences number of reported signals -too few signals – observers becomes bored and pays less attention -too many signals – observer becomes overwhelmed and cannot report them all - It has to be just right! (figure 11.5)

10. Tiredness, boredom and alertness at work • Performance decreases • with time • if the time intervals are too long • If the observer is fatigued or mentally stressed • If the environment is too hot or loud

11. Tiredness, boredom and alertness at work • Monotonous jobs • Tayloristic approach • During the 1920s, industrial workers were responsible for small, highly repetitive tasks • Good because the worker became highly skilled • Bad because led to repetition injuries and boredom

12. Tiredness, boredom and alertness at work • Satisfaction at work • Work preferences differ, but everyone wants to feel successful in their job • This requires communication between a manager and employees • Managerial control: higher level, focused on work design, organization and administration • Detail control: task level, workplace arrangement, tools and procedures • Having control over a task at work is empowering; lack of control/understanding can be stressful • Communication between team members can create a highly productive and stimulating social environment

13. Suitable postures at work • No static work • Fatigue in light to moderate work occurs as a result of maintaining a constant posture over a long period of time • Muscles are under constant contraction, blood cannot flow through the tissue and metabolic wastes accumulate • Muscles fatigue and have to rest • Blood can flow through the tissue, remove the metabolic wastes and recover

14. Suitable postures at work • Avoiding fatiguing body postures • Standing, stooping and kneeling • Examples of fatiguing conditions at work? • Sitting at work • Less tiring than standing • Different seated positions are suitable for different tasks • Too much sitting • Truck drivers and military pilots • Patients on bed rest – bedsores • Moving is essential for well-being and comfort

15. Accurate, fast, skillful activities • Exact manipulations • Light work is performed best in a work area at about waist height • Exact manipulations may require arm rests • Microscope work is difficult because neck muscles remain static – images can now be projected onto a monitor • Seeing what we are doing • Having to twist your neck to see what you are doing at work results from poor ergonomic planning • Normal LOS is angled downward • Eye movements 15 degrees above and below the LOS are comfortable (figure 11.16) • Therefore a viewing task works best within a well lit 30 degree range

16. Accurate, fast, skillful activities • Better Tools • Constant bending results from improper design • Flaws in design must be adjusted (figures 11.17, 11.18) • Repetitive Work • Leads to injuries of muscle, CT and joints • Affects both physical laborers and desk workers • Human body is not designed for repetitive actions (Table 11.2) • Low back, wrists, shoulders and elbows are the most common areas affected by repetition

17. Accurate, fast, skillful activities • Rest breaks • Both physiologically and psychologically beneficial • Many short breaks are more beneficial than few longer breaks • Breaks help to avoid monotony, prevent overload, allow for social interaction and a chance to restore energy supplies with food

18. Summary • Light and moderate tasks don’t impose heavy physical burdens but require attention to detail for long periods • HR is a useful indicator of physical strain, but can also be affected by emotions; questionnaires can also be used • Some people enjoy consistency and repetition in their jobs; others enjoy challenging, diverse tasks • Job satisfaction is greatest when the job is neither too complex nor too simple • Physical fatigue can result from static positions as well as overexerting muscles • Viewing tasks are best performed within a 30 degree cone in front of the body • Repetition increases skill level but puts the worker at risk for repetition injuries • Breaks are both physiologically and psychologically beneficial • Many short breaks are more beneficial than few longer breaks