Transcript lecture
CHAPTER IV BODY MECHANICS Body Mechanics • Definition: the use of one’s body to produce motion that is: -safe, -energy conserving, -and efficient, all of which allows the person to maintain balance and control Why Learn about Proper Body Mechanics? • Ensures clinician and patient safety • Places less stress and strain on the body, preventing injury • To conserve energy Benefits of proper Body Mechanics Conserve energy Reduce stress and strain to muscles, joints, ligaments, and soft tissue Promote effective, efficient respiratory and cardiopulmonary function Promote and maintain proper body control and balance Promote effective, efficient, and SAFE movements Terminology • Gravity: The force that pulls all objects toward the center of the earth. • Friction: The act of rubbing one object against another. Center of gravity (COG): • The point at which the mass of a body or object is centered; when weight on all sides is equal • Base of Support (BOS): Area on which an object rests and that provides support for the object • Line of Gravity: The vertical line between the center of gravity and the ground Must fall within the BOS if the “body” is to stay upright May be shifted Proper Body Mechanics • Gravity & Friction are forces that add resistance to many activities - lifting, reaching, pushing, pulling, and carrying an object. • Select and use techniques that: - reduce the adverse effects of gravity or friction - and/or enhance the positive effects of these TWO forces. Principles of Body Mechanics • Remain close to the object • Use short lever arms for better control & efficiency (with less strain) • The synchronized use of as many large muscle groups as possible during activity increases overall strength and prevents muscle fatigue and injury – To move objects below your center of gravity, begin with the hip and knees flexed – Use gluteal and leg muscles rather than the sacrospinal muscles of the back to exert an upward thrust when lifting weight – Face the direction of the movement to prevent twisting of the spine Maintain your COG close to the object’s COG • Widen your BOS and position your feet according to the direction of movement you will use to perform the activity • Avoid twisting your body when you lift • When possible, push, pull, roll, or slide an object rather than lifting it • The greater the friction against a surface beneath an object, the greater force required to move an object. Provide a firm smooth, dry foundation before moving the object. Causes of Back Injuries • Repetitive Motion/twisting • Forward bending • Poor or improper lifting techniques • A loss of flexibility • Poor posture • Poor Job design • Deconditioned/Poor physical fitness • Overweight/Smoking • Nutrition/Stress Mechanics: Twisting • Repetitive twisting can do damage to the spine. • It over stretches ligaments and muscles causing weakness. • Can damage discs especially combined with bending. Mechanics: Forward Bending • Forward bending can over-stretch the low back muscles to the point where they can lose strength to protect the spine from injury. • The ligaments are also weakened • Can increase stress on the discs • Range of the bend and time spent in the position can determine amount of damage Mechanics: Poor Posture • It is one of the main reasons that injuries occur • Means that the spine’s normal curves are exaggerated or decreased creating stresses and strains in the tissues. • The result is pain and dysfunction and can lead to serious injury. Mechanics: Poor Job Design/ Ergonomics Injury can occur when: • Moving a load too heavy • Moving a load too often • Moving a load too far • Twisting with a load • Vibration • Improper chair/equipment Poor ergonomics Mechanics: Poor Physical Fitness • Decreased oxygen delivery to muscles can cause muscles to wear down and lead to weakness. • This is one of the main cause for injury Mechanics: Overweight & Smoking • Obesity causes extra work for the spinal muscles to maintain the curvature. • Leads to excess fatigue and wear/tear in the body • Nicotine damages connective tissue decreasing circulation and oxygen in the blood which affects muscle strength Mechanics: Nutrition & Stress • Malnutrition can lead to injury. Because - Muscles need protein to repair worn musculoskeletal tissue - Bones need minerals for strength • Stress stiffens and weakens back muscles and increases pain sensitivity PROPER LIFTING TECHNIQUES • Stand with feet apart one foot slightly ahead of the other. Wide stance helps balance during lifting • Squat down keeping back straight, keep chin tucked, and lift smoothly • Keep object close to you • Bend your knees and hips using legs to lift Proper Lifting Techniques • Maintain lumbar curve • Face the object you are picking up • Push rather than pull (Pushing is easier) • Stabilize hands on the object • Take your time-hurrying causes muscles to act inappropriately and increases chance of injury Lifting (Don’ts) When lifting objects, DO NOT: • Lift in a bent-over, stooped position • Twist at waist • Lift with one hand • Lift with outstretched arms • Keep feet together • Lift above shoulders or below knees Avoid being STATIC • Change stressful positions often • If you are sitting for too long- stand • If you are standing for too long- stop and squat • If you are working in computer give a break every 30 minutes. Sitting and Computer station work • Sit close to your work • Hips, knees and ankles are open to 90 degrees • Elbows are open to 90-120 degrees • Wrists are in relaxed and neutral position (not bent) • Both feet are flat on the floor or use a foot rest • Shoulders are low and relaxed • Head and neck are aligned with spine Sitting and Computer work station • Do not slump or lean forward or downward to reach for work. • Do not sit for more than 60 minutes without getting up or changing position. • Raise the height of the computer screen so screen is at or slightly below eye level. Proper ergonomics Standing • Bring your work close to you. • Put one foot up, shift your weight and position frequently. • Keep your work at a comfortable height. • Wear comfortable shoes Standing (Don’ts) DO NOT: • Stand in one place too long. • Stand bent forward at your waist or neck. • Lock your knees into a straight or overextended position. Pushing • Push whenever possible. • Keep head up, knees bent, and back straight. • Keep the load in front and use both hands. • Remain close to the item being pushed. Reaching When reaching for an object, remember to: • Keep back straight • Reach with two hands • Face the object • Stand on a stable step-stool to reach high items • Bend knees slightly. Reaching (Don’ts) When reaching for an object, DO NOT: • Overreach by standing on toes • Reach with one hand • Twist at waist • Stand on an unsafe surface • Reach with legs locked in straight position.