CHAPTER 6 Balance Posture and Locomotion 1 Age Associated Changes in the Systems Contributing to Balance and Mobility Inevitable a b Postural control is effected when multiple systems fall below threshold of function c Reduced ability to perceive quickly and accurately where the body is in space which in turn compromises performance in speed accuracy balance strength and coordination d Reduced ability to quickly accommodate changing task and environmental demands e Balance is controlled by sensory system which includes vision somatosensation and vestibular reduced acuity contrast sensitivity depth perception and narrowing of i Vision visual field Results in slower processing info less efficient integration and possibly altered perception 1 Related diseases include cataracts glaucoma and macular degeneration a Due to peripheral neuropathy nerve damage 2 Wade study moved walls and ceilings but kept the floor still to see if the elderly would lose balance They increased postural sway proving their increased visual sensitivity Ring and Sundermeier did this with previously fallen elders they showed an even greater sway ii Somatosensation partial to complete loss due to peripheral neuropathy 1 Bruce the sensitivity of skin receptors and pressure declines as do the number of sensory pathways 2 Perret Reglis 2 to 10 fold increase in vibration threshold needed because of reduced ability to feel contact b t floor and feet This also included age related declines in both the number and sensitivity of muscle and joint receptors 3 Reduced sensation problem when rapid postural adjustments as a result of unexpected threat to balance occurs iii Vestibular biological sensors of head motion Begins at 30 with gradual decline in density of hair cells that serve as 1 By 70 vestibular ear hair and nerve cells decline as much as 40 2 Paige a Vestibulo ocular decrease reflex eye movement which makes it difficult to tell if the world is moving or they are This can cause problems in crowds traffic and stores because of complex visual enviornments a Dizziness is number 1 reason for 75 year old age group to go see i Loss of large motor neurons decline in important neurotransmitters such as dopamine and decline in nerve conduction velocity 1 Chronometric measure SRT and CRT movement time and RT reveals that action planning phase is the most declined ii Spirduso iii Stelmach 1 Reduced ability to inhibit inappropriate responses iv Loss of fast twitch motor units 3 Sloane f Motor System Changes physician a Declined motor unit firing and loss of anticipatory postural abilities lead to slower processing speeds and increases risk of falling v Results in longer movement execution times vi Decreases muscular strength power and endurance 1 Erim 1 Lindle a 50 70 strength lowers by 30 and decreases even more by 80 vii Loss of muscle power is most important factor for response itme g Cognitive System Affects 10 over 65 and 50 over 80 i Cognitive impairment important intrinsic risk factor for falls Which includes attention memory and intelligence ii Brown iii Brauer 1 Dividing attention between tasks becomes harder 1 Ability to recover from unbalanced posture becomes harder 2 After 2nd task it became even more difficult to restore balance h Gait iv Contribute to postural instability and subsequent falls in balance impaired Gait speed is 20 slower i Decreased 1 Velocity 2 Step length 3 Step frequency 4 Stride length 5 Swing phase ii Increased 1 Stance phase 2 Time in double support 2 Evaluating the Multiple Dimensions of Balance static and dynamic balance a Standing upright in space requires you to maintain COM with the confines of BOS and can be tested by a static balance task b Walking learning through space or transferring requires continual changes in BOS because COM moves beyond BOS and can be tested by dynamic balance tasks 3 Limiting factors of an individual s maximal limits of stability LOS a How far older adults are able to lean in any direction without changing their BOS constitutes their stability limits b 12 forward and backward and 16 laterally Nashner c LOS can be caused by musculoskeletal abnormalities or reduced ROM at ankles or neurological trauma i Vary according to biomechanical limits task being performed and constraints of environment d Postural control strategies of ankle hip and steps are included as limiting factors i Ankle Must have adequate ROM and strength surface must be firm and ii Hip Any weakness in the adductor and abductor muscles will adversely affect muscle must have adequate sensation stability especially when walking iii Step Must be able to establish new BOS and effected by lower limb strength and the speed of the initiation step Is slowed with age and has reduced somatosensation in feet and below normal ROM 4 Risk factors associated with falls among older adults a Muscle weakness b History of falls c Gait deficit d Balance deficit e Use of assistive device f Arthritis g h Depression i j Over 30 Cognitive impairment Impaired activities of daily living 5 Intervention strategies to reduce fall risk includes Long term exercise a b Environmental modifications c Multi factorial risk assessments d Health promotion and education e Medication withdrawal f Hip protector garments reduce fractures g CHAPTER 9 Health Exercise and Cognitive Function 1 Studies by Spirduso Scan table 6 3 and 6 4 FAB scale and BBS scale both balance scales with dynamic and static tests a Age by physical activity cross sectional study of reaction time between young exercisers young non exercisers old exercisers and old non exercisers i Old ex were faster at simple and choice reaction time SRT and CRT than old non but didn t differ from young b Did the only animal study on rats with Farrar even maintain their fastest RT c Both support the fitness to cognition relationship 2 The fractionated reaction time i Young rats increased oxidative capacity after training but old sedentary didn t a SRT and CRT of old exercisers were faster than non exercisers i Fractionation proved the reason was due to exercise difference in the premotor time PMT Clarkson and MacRae ii PMT for exercisers was 187 which non exercisers was 247 so this increase also gave non exercisers a larger movement time MT The contractile time CT was similar 3 Study by Dustman et al a Only positive findings b t fitness and intelligence cognition b Participants who trained also got higher scores on a multi fair intelligence test c Cognitive performance was