Protective Arm Balance Responses

Participants will be involved in 6 sessions. Session 1 will include the assessment, questionnaires, and training. Session 2 will include just the training. Session 3 will include the assessment and training. Sessions 4-5 will include just the training. Session 6 will include the assessment, questionnaires, and training.

Assessment:

Using a specialized treadmill that induces balance perturbations (ActiveStep, www.simbex.com), an individualized perceived balance threshold will first be assessed. In brief, participants will stand feet together, arms relaxed at their sides, eyes focused on a red 'X' at eye level and asked only to grasp when participants feel a true need to restore balance. Testing perturbations will proceed 2 levels above this threshold. Next, two lateral perturbation conditions, each with 10 trials (5x right; 5x left) will be randomly applied. Perturbation direction and timing will be unknown and random. Condition 1 has no cognitive task. Condition 2 has participants engaged in a cognitive task 30-120s prior to perturbation with instructions, "as soon as the participant feels a falling sensation, stop the task and grab a single rail to quickly restore balance." To promote high cognitive task engagement, a mental arithmetic task was selected as one of the most effective stressors. Psychophysiological stressors are known to result in greater task engagement than pleasant tasks, thus adding a consistent challenge to task inhibition and in turn, attention switching. To allow characterization of the 'first trial response', the first and second trial will include one of each condition, separated by a 5min rest. The 'first trial response' has less stability compared with subsequent perturbations and is relevant to the study of mechanisms underlying 'real-life' falls. Objective kinematic and electromyographic (EMG) assessment of balance responses to the perturbations will be conducted. Following the balance perturbation assessment, clinical tests of balance, including the four square step test and miniBEST, will be conducted. The investigators will also be using a device to record physiological responses using sensors attached to the fingers (Biopac Systems, Inc.) to record stress at baseline and during the reactive balance responses assessment.

Subjects will also complete questionnaires on balance confidence and anxiety. These include:

• Activity specific balance confidence scale (ABC): Questions are on how confidence subjects feel when performing normal activities of daily living that involves maintaining their dynamic balance.
• Stait Trait Anxiety Inventory: Measure of trait and state anxiety
• Subjective Units of Distress Scale (SUDS): Measures anxiety and distress on a scale of 0 no distress and totally relaxed to 100 highest distress/ anxiety ever felt
• Mini Mental State Examination (MMSE): A validated sensitive test for detecting mild cognitive impairments. It involves documenting the participants responses to cognitive tasks such as c subtractions, memory recall repeating number sequences, naming as many nouns starting with "F" etc.
• Beck Anxiety Inventory (BAI): Consists of 21 self-reported items (four-point scale) used to assess the intensity of physical and cognitive anxiety symptoms during the past week

Training:

Participants will each undergo 6 sessions of an attention task combined with balance perturbation and upper limb responses. The investigators define feasibility in terms of whether key components of our approach are met, including valid and reliable pre-perturbation cognitive engagement and reactive arm recovery responses over repeated trials, as well as overall participant satisfaction.

Inclusion criteria

• 65 to 88 years of age
• Community ambulatory with or without a straight cane

Exclusion criteria

• Significant musculoskeletal or neurological impairments as indicated by limitations in activities of daily living, ADL (less than 6/6 on Katz Index in ADLs)
• Clinically identified uncorrected visual loss
• Complaints of dizziness or known vestibular disorder
• Upper extremity strength less than 4/5 manual muscle test at the shoulder, elbow, wrist, or grip.
• Mini Mental State Examination score of less than 25