The effects of physical exercise training in combination with cognitive training on dual task costs of walking in elderly

Gait was measured with a GAITRite instrumented walkway (CIR Systems, USA) before and after twelve weeks of training. The GAITRite system provided temporal (time) and spatial (distance) gait parameters via an electronic walkway connected to the serial port of a personal computer. The GAITRite walkway contained sensor pads encapsulated in a roll-up carpet with an active area of 7.3 m long. As the subject walked through the walkway, the sensors captured each footfall as a function of time and transferred the gathered information to a personal computer to process the raw data into footfall patterns. The GAITRite walkway was extended with a 2.5 meter carpet at the end and beginning of the active area to eliminate the effect of acceleration or deceleration and allow for steady state gait assessment. For each subject the relative dual task costs (DTC) of walking was calculated, as percentage of loss relative to the single-task walking performance, according to the formula DTC [%] = 100 * (single-task score - dual-task score)/single-task score

1. Physical performance:
The Expanded Timed Get-up-and-Go (ETGUG) test measures the overall time to complete a series of functionally important tasks. The ETGUG test is a sensitive and objective assessment of physical function.
2. Fear of falling:
The Falls Efficacy Scale International (FES-I) questionnaire was used as a measure of ‘concern’ about falling to determine the transfer effects of training to activities of daily living. This scale assesses both easy and difficult physical activities and social activities with a scale of: 1 = not at all concerned, 2 = somewhat concerned, 3 = fairly concerned, 4 = very concerned.
3. Simple Reaction Time
These tasks are frequently used to measure psychomotor speed. Reaction time is assessed in milliseconds using a hand-held electronic timer and a light as the stimulus and depression of a switch by the finger and the foot as the responses. The light stimulus is located adjacent to the response switches and is bright (ie, supra-threshold) to ensure that the tests are not influenced by the subject’s visual acuity. The timer has a built-in variable delay of 1 to 5 seconds to remove any cues that could be gained from the test administrator commencing each trial by pressing the “start” button. A modified computer mouse is used as the response box for the finger press task, and a pedal switch is used for the foot press task (Figs. 2A and 2B). Five practice trials are undertaken, followed by 10 experimental trials.
4. Postural Balance (SPPB)
The Short Physical Performance Battery (SPPB) is an objective assessment tool for evaluating lower extremity functioning in older persons. It was developed by the U.S.A. National Institute on Aging. The SPPB is composed of three timed tests: 3-meter walking speed, balance, and chair stand tests. Timed results from each test are categorized into 5-level variables ranging from 0 (worst performers) to 4 (best performers) according to well-established cut-points. The sum of the results from the three categorized tests (ranging from 0 to 12) is used for the analyses. This battery has been extensively validated, is predictive at the pre-clinical stage of later disability and has application in routine clinical settings in monitoring the functioning of older people. The standing balance portion requires participants to maintain a side-by-side, semi-tandem, and tandem stance for 10 seconds, with scores ranging from 0 to 4 (maximum score). The fastest time of two 4 m usual-pace walk attempts is used. The chair stands required participants to rise from a chair with arms across their chest for five repetitions. Categorical scores (range 0–4) for the 4 m walk and chair stands are based on timed quartiles previously established in a large population. Individuals unable to complete either task receive a score of 0. The sum of the three components comprises the final SPPB score with a possible range from 0 to 12 (12 indicating the highest degree of lower extremity functioning). The participants are tested within a single session that lasts about 10 minutes.
5. Executive Function (Trail Making A & B-Test) The Trail Making Test (TMT) provides information on visual search, scanning, speed of processing, mental flexibility, and executive functions. The TMT consists of two parts. TMT-A requires an individual to draw lines sequentially connecting 25 encircled numbers distributed on a sheet of paper. Task requirements are similar for TMT-B except the person must alternate between numbers and letters (e.g., 1, A, 2, B, 3, C, etc.). In Part B, participants are asked to connect circles containing numbers (from 1 to 13) or letters (from A to L) in an alternating numeric, alphabetical order (1-A-2-B-3-C, etc.). Errors must be corrected immediately and the sequence re-established. The test is terminated after 10 minutes even if it is not completed. The score on each part represents the amount of time required to complete the task. Performance on the TMT is a strong, independent predictor of mobility impairment, accelerated decline in lower extremity function, and death in older adults. The participants are tested within a single session that lasts about 5-10 minutes.
6. Cognitive Functioning: Vienna Test System The Vienna Test System (VTS) is known worldwide as a leading computerized psychological assessment tool. It is developed by Schuhfried Test Instruments. The use of the computer ensures the highest possible level of objectivity and precision and enables dimensions to be tested that could not be measured by traditional paper-and-pencil tests. In addition, the scoring of test results is guaranteed to be fast and accurate.
For the older adults aimed at in this study the following test will be used:
WAF – Perception and Attention Functions The following test of the Vienna Test System is linked to our cognitive exercise training program:
WAFG (Divided attention)
The respondent receives stimuli on two visual or rather one visual and one auditory canal. The respondent’s task is to observe, if one of the stimuli has changed two times in series.
For each of the WAF tests different test forms are available, enabling dimensions of attention to be assessed under different presentation modalities. Thus the WAF tests systematically include sub-tests for visual, auditory and cross-modal presentation. In some subtests of the WAF test battery automated and controlled aspects of attention are measured separately; the stimuli either become more prominent because the intensity level is increased ("popping out"), or they become less prominent because their intensity is decreased and cognitively controlled "top down" processes are then required.