week 2

• Many of our activities require physical effort and the careful handling of materials, goods, supplies and equipment manually
• Things to pay attention to in physical workload

  • Working method
  • Working posture
  • Speed/rate of work
  • Design and construction of work tools
• Physical Workload


  • Stress: heavy work, heat and cold, noise, sleep loss, overload
  • Strains: the effects of stress towards individuals
• Types of workload known in ergonomics

  • Physical Energetic Workload: Static and Dynamic Workloads
  • Perceptive Mental Workload: Mental Work of the Brain and Five Senses
  • Biomechanical Workload: Static and Dynamic Loads relate to the Position (attitude) of the body or body parts
• Standard method for Physical Work Measurement

  1. Direct Calorimetry: Using tools like Chamber Calorimetry

  2. Indirect Calorimetry: Measuring oxygen consumption and CO2 production
• Indirect Calorimetry


  The tool used is a spirometer. Measuring oxygen consumption and CO2 production, with the energy formation process: Food + O2 -> CO2 + Energy
• Indirect metabolic measurements generally use physiological response variables body which has a high correlation with metabolic processes, especially with use or consumption of O2 the body during dynamic aerobic work
• Workload Levels according to Faal Variables, Christensen (1964)


  • Light
  • Rather Heavy
  • Heavy
  • Very Heavy
  • Outside Normal
• Many jobs around us require the process of moving materials carried out by humans (manually)
• Examples of manual material handling work

  • Loading & Unloading Boxes / Cartons
  • Removing Materials from Conveyor Belts
  • Stacking Items in a Warehouse
• Materials Handling Approaches


  • Biomechanics Approach
  • Physiological Approach
  • Psychophysical Approach
• Biomechanics Approach


  Sees the human body as a system consisting of interconnected body parts
• Physiological Approach


  Calculates energy consumption and pressure that occurs in the cardiovascular system and is most suitable for use in Material Handling work carried out at high frequencies over a certain period of time
• Psychophysical Approach


  Is a combination of biomechanics and physiology, which is used to determine MAWL (Maximum Acceptable Weight of Load)
• Factors that influence the level of pressure generated when lifting a load

  • Position of horizontal object (load)
  • Height and distance of appointment
  • Method of lifting from the floor
  • Frequency of appointment
  • Characteristics of objects (size, shape, distribution and stability of load, handles)
• Types of load limits recommended when carrying out manual materials handling work

  • Biomechanical Recommended Limits
  • Physiological Recommended Limits
  • Psychophysical Recommended Limits
• Biomechanical Recommended Limits


  Focus on two main factors: Strength (Strength) and Compressive Forces
• The physiological model, in determining the load limits that can still be recommended by a human, is formulated as: E = F x a x W x C/1000
• Psychophysical recommended limits: MAN below 5 kilocalories/minute in an average of 8 hours, WOMAN no more than 3.35 kilocalories/minute in an average of 8 hours, HEART RATE no more than 115 beats/minute, FOR VERY HEAVY WORK (≥8 kcal/Minute), 80% of working time is required to rest
• Based on data from the National Institute for Occupational Safety & Health (NIOSH), the types of diseases that will arise as a result of Material Handling work: Bone fractures, Bronchitis, Cardiovascular strains, Increased Blood Pressure, Muscular Fatigue, etc.
• The type of material handling that dominates the incidence of back injuries is lifting objects, with the following data: 50% - Lifting Objects, 9% - Pushing/Pulling Objects, 6% - Holding, Welding, Carrying
• Workload Assessment Methods


  • RULA
  • REBA
  • Physiological Strain Measurement
  • NIOSH Lifting Guides
• RULA


  Ergonomic assessment method popular in industry, easy to use, good for manufacturing industry, fast, does not require complicated calculations, validated
• REBA


  Same principles as RULA, validated, better assessment of the whole body, easy to use, good for the service and health industries
• Physiological Strain Measurement


  Measures energy expenditure using oxygen consumption and heart rate
• NIOSH Lifting Guidelines


  To assess the physical stress of two-handed lifting, calculate the recommended maximum safe lifting load
• Factors in the NIOSH Lifting Equation

  • Load Constant
  • Horizontal Multiplier
  • Vertical Multiplier
  • Distance Multiplier
  • Asymmetric Multipliers
  • Frequency Multiplier
  • Coupling Multiplier
• Job Redesign Recommendations


  • Reduce manual materials handling (MMH)
  • Decrease weight
  • Use 2 or more people where possible
  • Push or pull vs. Lift & carry
  • Minimize carrying distance
  • Stacking height < shoulder height
  • Heavy objects at knuckle height
  • Reduce lifting frequency
  • Provide rest periods
  • Use job rotation
  • Provide handles
• References


  • Human Factors In Engineering and Design (Mark Sanders, Ernest McCormick)
  • Human Factors and Ergonomics Design Handbook (Barry Tillman, David Fitts, Wesley Woodson)
  • Human Factors in Systems Engineering (Alphonse Chapanis)
  • Handbook of Human Factors and Ergonomics Method (Neville Stanton)
  • Journal and Scientific Article
  • Lecture Notes