Physiology and Anthropometrics

Physiology and anthropometrics Erik Prinsen ROESSINGH RESEARCH & DEVELOPMENT A F F I L I AT E D W I T H U N I V E R S I T Y O F T W E N T E Can the body cope? Anatomy Anthropometry Physiology...

Physiology and anthropometrics Erik Prinsen ROESSINGH RESEARCH & DEVELOPMENT A F F I L I AT E D W I T H U N I V E R S I T Y O F T W E N T E Can the body cope? Anatomy Anthropometry Physiology Risk of getting hurt Biomechanics PHYSICAL ERGONOMICS – PHYSIOLOGY AND ANTHROPOMETRY 2  Let’s extend that model a bit Vink and Hallbeck, 2012 Environment Expectations Person Comfortable Internal Perceived Feel Product characteristics Interaction Human Effects Nothing Body Effects Musculoskeletal Discomfort complaints Usage/task PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 3  Let’s extend that model a bit Vink and Hallbeck, 2012 Contact between the Environment human body and a Expectations product Person Comfortable Internal Perceived Feel Product characteristics Interaction Human Effects Nothing Body Effects Musculoskeletal Discomfort complaints Usage/task PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 4  Let’s extend that model a bit Vink and Hallbeck, 2012 Environment Expectations Person Comfortable Internal Perceived Feel Product characteristics Interaction Human Effects Nothing Body Effects Musculoskeletal Discomfort complaints Usage/task Interaction leads to internal effects, such as tactile sensations, body posture change or muscle activation PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 5  Let’s extend that model a bit Vink and Hallbeck, 2012 Environment Expectations Person Comfortable Internal Perceived Feel Product characteristics Interaction Human Effects Nothing Body Effects Musculoskeletal Discomfort complaints Usage/task Perceived effects are modified by internal effects but also expectations PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 6  Let’s extend that model a bit Vink and Hallbeck, 2012 Environment Expectations Person Comfortable Internal Perceived Feel Product characteristics Interaction Human Effects Nothing Body Effects Musculoskeletal Discomfort complaints Usage/task Feedback loop: in case of discomfort, for instance posture is changed, a product/task is adapted, or usage is stopped PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 7  Up to now Vink and Hallbeck, 2012 Environment Expectations Person Comfortable Internal Perceived Feel Product characteristics Interaction Human Effects Nothing Body Effects Musculoskeletal Discomfort complaints Usage/task How the human body is built PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 8  Next step (this lecture) Vink and Hallbeck, 2012 Environment Expectations Person Comfortable Internal Perceived Feel Product characteristics Interaction Human Effects Nothing Body Effects Musculoskeletal Discomfort complaints Expand this knowledge by: Usage/task Interaction in terms of physiology and how the interaction is different for different users. All in the context of internal effects and MSDs PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 9  Next step (upcoming lectures) Vink and Hallbeck, 2012 Environment Expectations Person Comfortable Internal Perceived Feel Product characteristics Interaction Human Effects Nothing Body Effects Musculoskeletal Discomfort complaints Expand this knowledge by: Usage/task Interaction and internal human body effects in terms of biomechanics in the context of perceived effects and MSDs PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 10  Physiology Vink and Hallbeck, 2012 Environment Expectations Person Comfortable Internal Perceived Feel Product characteristics Interaction Human Effects Nothing Body Effects Musculoskeletal Discomfort complaints Usage/task PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 11 What can happen in the human body in response to a product or task PHYSICAL ERGONOMICS - INTRODUCTION 12 Bear with me…. Internal Human Energy systems Muscle model Body Effects Internal Human Musculo- Body effects in Discomfort skeletal load terms of MSDs PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 13 Physiology Heart and Nervous Lungs Digestive Muscles blood vessels system system PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 14 Bear with me…. Internal Human Energy systems Muscle model Body Effects Internal Human Musculo- Body effects in Discomfort skeletal load terms of MSDs PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 15 Energy systems When talking about internal human body effects, we often talk about exercise physiology and the use of different energy systems One of the key molecules when talking about exercise physiology is ATP ATP is the source of energy use and storage at the cellular level PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 16 ATP PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 17 Energy systems Energy systems Immediate Anaerobic Aerobic system metabolism metabolism (no oxygen) (no oxygen) (oxygen) PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 18 Physiology – energy systems 1. Immediate system Needs no oxygen Uses small amount of ATP that is available in the human body Last 10-30 seconds of high-intensity exercise (90-100% maximal heart rate) 2. Anaerobic metabolism Needs no oxygen Breaks down glucose into ATP, water and lactic acid 30 seconds to 3 minutes of moderate to high-intensity exercise (75- 90% maximal heart rate) PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 19 Physiology – energy systems 3. Aerobic metabolism Uses oxygen Breaks glucose and fatty acids down into ATP Used for low- to moderate activity for longer than 3 minutes (up to 75% maximal heart rate) PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 20  Anaerobic Energy systems PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 21 Why are these energy systems of interest in the context of physical ergonomics? PHYSICAL ERGONOMICS - INTRODUCTION 22 Lactic acid Lactic acid Muscle pain Muscle performance Increased risk Discomfort for MSDs And increased muscle stiffness PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 23 Bear with me…. Internal Human Energy systems Muscle model Body Effects Internal Human Musculo- Body effects in Discomfort skeletal load terms of MSDs PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 24 Muscle load PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 25 Musculoskeletal load If active component decreases, the overall muscle force that can be produced decreases If the load stays the same, other muscles and or the load of joints will be increased After intense activity you probably had muscle pain at some point of muscles you didn’t know you had If those muscles are not properly trained → musculoskeletal disorders PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 26  Anaerobic Energy systems PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 27 How can we ensure that we stay in the aerobic metabolism PHYSICAL ERGONOMICS - INTRODUCTION 28 How to stay in aerobic metabolism Reduce the load that the product or tasks causes Ensure sufficient breaks Offer proper training PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 29 Seating assistance PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 30 Arm assistance PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 31 Let’s zoom in on muscle action PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 32 Muscle Muscles consists of two main Belly structures: Belly → the part that can Tendon produce force Tendon → the part that attaches the muscle to the skeleton. PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 33 Skeletal muscle PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 34 PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 35 Muscle force A muscle can exert force by forming cross bridges PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 36 Muscle contraction PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 37 Muscle contraction PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 38 Force-length curve 3 2 4 5 1 PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 39 Force-length curve 1. Low force production because of high overlap between thick and thin filament but there is not much sliding possible (limiting factor) 2. High force production possible because there is sufficient overlap between the thin and thick filaments for cross-bridging to occur and sliding is still possible although not a lot (limiting factor). 3. Highest force production possible. Great overlap between thin and thick filaments while a lot of sliding is possible. PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 40 Force-length curve 4. High force production possible because there is a lot of sliding possible but there is a limited overlap which influences the number of cross-bridging that can occur (limiting factor) 5. Low force production possible because there is a limited overlap between the thick and thin filaments so there is a low number of cross-bridges that can occur (limiting factor) PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 41 Force-length curve 3 2 4 5 1 PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 42 Muscle tension PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 43  3 2 4 5 1 PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 44 From brain to muscle PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 45 Contraction PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 46 Motor unit A motor unit is made up of a motor neuron and all the muscle fibers that it innervates PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 47 What determines the amount of force a muscle can produce? PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 48 Muscle force Force is dependent on: Thickness muscle belly Direction of the fibers Length of a muscle Lever arm PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 49  Parallel (a) Penate (b,c) Force: Direction of the fibers Which muscle can produce more force? Which muscle can produce a larger range of motion? PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 50 Muscle force Parallel muscle Pennate muscle Small cross-section Large cross-section → smaller force → greater force Long muscle fibers Short muscle fibers → long range → smaller range PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 51 Moving is contracting muscles Forms of muscle contractures ◦ Concentric ◦ Eccentric ◦ Isometric PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 52 Muscle actions PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 53 Which muscle contraction is the most likely to lead to MSDs? PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 54 Anthropometry PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 55 Anthropometry Products are usually designed for the average person PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 56 Physical factors and average user PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 57 Physical factors and the average user PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 58 Anthropometry and ergonomics PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 59 Assignment time PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 60 Best ergonomic chair (NY Times) PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 61  Three variations Small Medium Large Height chair 97.8 cm 104.1 cm 109.2 cm Width chair 40 cm 43 cm 46 cm Depth seat 42.5 cm 42.5 cm 47 cm Maximal seat height 48.2 cm 52.1 cm 52.1 cm Minimal seat height 38.1 cm 40.6 cm 40. 6 cm Weight capacity 150 kg 175 kg 175 kg PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 62 Does this fit the average user? PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 63 ANSUR II database The Anthropometric Survey of US Army Personnel 93 measures for 6068 adult US military personnel (4,082 men and 1,986 women) Not an approximation of the general population, but it will do for educational purposes PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 64 Canvas Four documents: Measurement handbook Assignment description Excel file with data of males Excel file with data of females PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 65 Assignment 1. Look in the handbook for the measure corresponding with the width of the chair 2. Look in the handbook for the measure corresponding with the width of the chair 3. Look in the Excel files which proportion of the males and which proportion of the females do not meet the width of the chair PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 66 Example: chair width 1. Look in the handbook for the measure corresponding with the width of the chair Hip breadth, sitting PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 67 Assignment: chair width 1. Look in the handbook for the measure corresponding with the width of the chair 2. Look in the handbook for the measure corresponding with the width of the chair Hip breadth, AY PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 68 Assignment 1. Look in the handbook for the measure corresponding with the width of the chair 2. Look in the handbook for the measure corresponding with the width of the chair 3. Look in the Excel files which proportion of the males and which proportion of the females do not meet the width of the chair 2 persons do not meet the width of the chair PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 69 Assignment 1. Look in the handbook for the measure corresponding with the width of the chair 2. Look in the handbook for the measure corresponding with the width of the chair 3. Look in the Excel files which proportion of the males and which proportion of the females do not meet width of the chair 4. Calculate the percentage this group represents of the overall population (2/6068)*100% = 0.03% PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 70 Assignment 1. Look in the handbook for the measure corresponding with the depth of the chair 2. Look in the handbook for the measure corresponding with the height of the chair 3. Look in the Excel files which proportion of the males and which proportion of the females do not meet the minimum depth and minimum height of the chair 4. Calculate the percentage this group represents of the overall population PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 71 Anatomy, physiology and anthropometry: 10 Ergonomic principles PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 72 10 Ergonomic principles 1. Work in neutral postures Especially in static working positions, but also of importance for repetitive movements The torso, but also hand and wrist are of importance PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 73 10 Ergonomic principles 2. Reduce excessive force Excessive pressure or force at the joints can cause injury Better to minimize the work that requires more physical labor PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 74 10 Ergonomic principles PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 75 10 Ergonomic principles 3. Keep everything in reach PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 76 10 Ergonomic principles 4. Work at proper height PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 77 10 Ergonomic principles 5. Reduce excessive motions PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 78 10 Ergonomic principles 6. Minimize fatigue and static load PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 79 10 Ergonomic principles 7. Minimize pressure points PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 80 10 Ergonomic principles 8. Provide clearance PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 81 10 Ergonomic principles 9. Move, exercise and stretch PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 82 10 Ergonomic principles 10. Maintain a comfortable environment PHYSICAL ERGONOMICS - PHYSIOLOGY AND ANTHROPOMETRY 83