dr. katie cahill science 295. light and moderate work basic metabolic functions work the same as...
TRANSCRIPT
Dr. Katie CahillScience 295
Light and Moderate WorkBasic metabolic functions work the same as with
hard labor, but at a lower levelByproducts dissipated through the skin and
respirationBlood 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 workPsychosocial environment - getting along with co-
workers and supervisorsPhysics environment – temperature, humidity, noise
and lighting, arrangement of working hours (shiftwork)
Physiological and psychological principlesMost 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
Physiological and psychological principlesStairs 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 effectsHeart rate is the most useful indicator during light
work because it responds to static muscle loadingHR 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
Physiological and psychological principlesScaled judgments
A way to assess satisfaction is to ask for employee opinions Usually done through questionnaires:
1. Paired descriptors (p. 218)2. Ordinal scales – pain on a scale of 1-103. Interval scales4. Ratio scales – allow for mathematical calculations
Subjective, not objective informationStudies may generate awareness of problems
at work, which management may want to avoid
Physiological and psychological principlesNordic questionnaire
(figure 11.3)2 parts:
1. General information2. Area focused on
specific regions of the body-Body is divided into 9 regions and the person indicates where they experience musculoskeletal problems
Tiredness, boredom and alertness at workTiredness – the state in which we feel unable
or disinclined to continue a taskFatigue – 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
Tiredness, boredom and alertness at workDiversity 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
Tiredness, boredom and alertness at workVigilance 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)
Tiredness, boredom and alertness at workPerformance decreases
with timeif the time intervals are too longIf the observer is fatigued or mentally stressedIf the environment is too hot or loud
Tiredness, boredom and alertness at workMonotonous 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
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
Suitable postures at workNo 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 restBlood can flow through the tissue, remove the
metabolic wastes and recover
Suitable postures at workAvoiding fatiguing body postures
Standing, stooping and kneelingExamples of fatiguing conditions at work?
Sitting at workLess tiring than standingDifferent seated positions are suitable for
different tasksToo much sitting
Truck drivers and military pilotsPatients on bed rest – bedsoresMoving is essential for well-being and comfort
Accurate, fast, skillful activitiesExact manipulations
Light work is performed best in a work area at about waist height
Exact manipulations may require arm restsMicroscope work is difficult because neck muscles remain
static – images can now be projected onto a monitorSeeing 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 downwardEye 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
Accurate, fast, skillful activitiesBetter Tools
Constant bending results from improper designFlaws in design must be adjusted (figures 11.17,
11.18)Repetitive Work
Leads to injuries of muscle, CT and jointsAffects both physical laborers and desk workersHuman body is not designed for repetitive actions
(Table 11.2)Low back, wrists, shoulders and elbows are the
most common areas affected by repetition
Accurate, fast, skillful activitiesRest 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
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