Age effects on step adaptation during treadmill walking with continuous step length biofeedback.

BACKGROUND: The inability to adjust step length can lead to falls in older people when navigating everyday terrain. Precisely targeted forward placement of the leading foot, constituting step length adjustment, is required for adaptive gait control, but this ability may reduce with ageing. The objective of this study was to investigate ageing effects on step length adaptation using real-time biofeedback. RESEARCH QUESTION: Does ageing affect the ability to adapt step length to match a target using real-time biofeedback? METHODS: Fifteen older adults (67 ± 3 years; 8 females) and 27 young adults (24 ± 4 years; 13 females) completed a step length adaptation test while walking at preferred speed on a treadmill. The test involved walking while viewing a monitor at the front of the treadmill that showed a real-time signal of absolute left-right foot displacement. The task was to match the local maxima of the signal (i.e. step length) to two target conditions, at 10 % longer or 10 % shorter than mean baseline step length. When the target was displayed, it remained unchanged for a set of 10 consecutive step attempts. Three sets of 10 attempts for each target condition were allocated in random order, for a total of 30 step attempts per target. Average absolute error and average error (bias) of step length accuracy was computed for each target condition and compared between groups. RESULTS: The step adaptation test identified that older adults had greater mean absolute error for both short and long step targets and showed a step length-dependent bias significantly different to the young. SIGNIFICANCE: Real-time foot position feedback could be a useful tool to train and evaluate step adaptation in older people.

Real-time foot clearance biofeedback to assist gait rehabilitation following stroke: a randomized controlled trial protocol.

BACKGROUND: The risk of falling is significantly higher in people with chronic stroke and it is, therefore, important to design interventions to improve mobility and decrease falls risk. Minimum toe clearance (MTC) is the key gait cycle event for predicting tripping-falls because it occurs mid-swing during the walking cycle where forward velocity of the foot is maximum. High forward velocity coupled with low MTC increases the probability of unanticipated foot-ground contacts. Training procedures to increase toe-ground clearance (MTC) have potential, therefore, as a falls-prevention intervention. The aim of this project is to determine whether augmented sensory information via real-time visual biofeedback during gait training can increase MTC. METHODS: Participants will be aged > 18 years, have sustained a single stroke (ischemic or hemorrhagic) at least six months previously, able to walk 50 m independently, and capable of informed consent. Using a secure web-based application (REDCap), 150 participants will be randomly assigned to either no-feedback (Control) or feedback (Experimental) groups; all will receive 10 sessions of treadmill training for up to 10 min at a self-selected speed over 5-6 weeks. The intervention group will receive real-time, visual biofeedback of MTC during training and will be asked to modify their gait pattern to match a required "target" criterion. Biofeedback is continuous for the first six sessions then progressively reduced (faded) across the remaining four sessions. Control participants will walk on the treadmill without biofeedback. Gait assessments are conducted at baseline, immediately following the final training session and then during follow-up, at one, three, and six months. The primary outcome measure is MTC. Monthly falls calendars will also be collected for 12 months from enrolment. DISCUSSION: The project will contribute to understanding how stroke-related changes to sensory and motor processes influence gait biomechanics and associated tripping risk. The research findings will guide our work in gait rehabilitation following stroke and may reduce falls rates. Treadmill training procedures incorporating continuous real-time feedback may need to be modified to accommodate stroke patients who have greater difficulties with treadmill walking. TRIAL REGISTRATION: Australia New Zealand Clinical Trials Registry, ACTRN12617000250336 . Registered on 17 February 2017.

Tone Entropy Analysis of Augmented Information Effects on Toe-Ground Clearance When Walking.

Minimum toe clearance (MTC) is an event approximately mid-swing in the walking cycle that is critical for preventing unintended foot contact with surface irregularities ("tripping"). Treadmill-based gait training for older adults was undertaken using real-time augmented information to increase foot-ground clearance at MTC (MTC height). Ten young (Y) (Age: 23±2 year) and ten older (O) (Age: 76±9 year) participants undertook 10 min preferred speed treadmill walking (baseline) followed by 20 min with MTC height information (training) and 10 min without augmented information (retention). Three-dimensional lower limb position was sampled at 100 Hz from which MTC height was computed for each step cycle. MTC height data were analyzed using traditional descriptive statistics (mean and SD) and by computing tone (T) and entropy (E) to show, respectively, cycle-to-cycle changes to MTC height and the informational content of the MTC height time-series. There were significant ( ) age-group differences in T-E values of MTC height; Baseline ( Older=-5.40±2.00 (T); 6.63±0.23 (E); Young = -3.00±0.89 (T); 6.20±0.51 (E)), Training ( Older=-5.05±3.45 (T); 6.46±0.42 (E); Young = -2.55±0.67 (T); 6.75±0.39 (E)) Retention ( Older=-3.77±2.59 (T); 6.38±0.46 (E); Young = -2.55±0.67 (T); 6.26±0.39 (E)). Relative to baseline, tone value was significantly ( ) reduced and entropy was elevated in training and vice versa in retention phase for the young group but no significant trends were observed for older group. T and E measures of MTC height considered separately discriminated the age groups only in baseline but distinctive "clusters" were observed in tone versus entropy plots indicating characteristically different patterns of MTC adjustment over step cycles. Treadmill training with MTC height augmented information is a practical intervention for reducing tripping in older people and others with gait impairments. T-E analysis is useful for identifying characteristics of lower limb control with ageing that have not been previously recognized in studies employing traditional statistical analysis of the MTC event.

A real time biofeedback using Kinect and Wii to improve gait for post-total knee replacement rehabilitation: a case study report.

PURPOSE: This study aimed to develop a low-cost real-time biofeedback system to assist with rehabilitation for patients following total knee replacement (TKR) and to assess its feasibility of use in a post-TKR patient case study design with a comparison group. METHOD: The biofeedback system consisted of Microsoft Kinect(TM) and Nintendo Wii balance board with a dedicated software. A six-week inpatient rehabilitation program was augmented by biofeedback and tested in a single patient following TKR. Three patients underwent a six weeks standard rehabilitation with no biofeedback and served as a control group. Gait, function and pain were assessed and compared before and after the rehabilitation. RESULTS: The biofeedback software incorporated real time visual feedback to correct limb alignment, movement pattern and weight distribution. Improvements in pain, function and quality of life were observed in both groups. The strong improvement in the knee moment pattern demonstrated in the case study indicates feasibility of the biofeedback-augmented intervention. CONCLUSION: This novel biofeedback software has used simple commercially accessible equipment that can be feasibly incorporated to augment a post-TKR rehabilitation program. Our preliminary results indicate the potential of this biofeedback-assisted rehabilitation to improve knee function during gait. Research is required to test this hypothesis. Implications for Rehabilitation The real-time biofeedback system developed integrated custom-made software and simple low-cost commercially accessible equipment such as Kinect and Wii board to provide augmented information during rehabilitation following TKR. The software incorporated key rehabilitation principles and visual feedback to correct alignment of the lower legs, pelvic and trunk as well as providing feedback on limbs weight distribution. The case study patient demonstrated greater improvement in their knee function where a more normal biphasic knee moment was achieved following the six-week biofeedback intervention.

Biofeedback training effects on minimum toe clearance variability during treadmill walking.

A number of variability analysis techniques, including Poincaré plots and detrended fluctuation analysis (DFA) were used to investigate minimum toe clearance (MTC) control during walking. Ten young adults walked on a treadmill for 10 min at preferred speed in three conditions: (i) no-intervention baseline, (ii) with biofeedback of MTC within a target range, and (iii) no-biofeedback retention. Mean, median, standard deviation (SD), and inter quartile range of MTC during biofeedback (45.57 ± 11.65, 44.98 ± 11.57, 7.08 ± 2.61, 8.58 ± 2.77 mm, respectively) and retention (56.95 ± 20.31, 56.69 ± 20.94, 10.68 ± 5.41, 15.38 ± 10.19 mm) were significantly greater than baseline (30.77 ± 9.49, 30.51 ± 9.49, 3.04 ± 0.77, 3.66 ± 0.91 mm). Relative to baseline, skewness was reduced in biofeedback and retention but only significantly for retention (0.88 ± 0.51, 0.63 ± 0.55, and 0.40 ± 0.40, respectively). Baseline Poincaré measures (SD1 = 0.25, SD2 = 0.34) and DFA (α1 = 0.72 and α2 = 0.64) were lower than biofeedback (SD1 = 0.58, SD2 = 0.83, DFA α1 = 0.76 and α2 = 0.92) with significantly greater variability in retention compared to biofeedback only in the long-term SD2 and α2 analyses. Increased DFA longer-term correlations α2 in retention confirm that a novel gait pattern was acquired with a longer-term variability structure. Short- and long-term variability analyses were both useful in quantifying gait adaptations with biofeedback. The findings provide evidence that MTC can be modified with feedback, suggesting future applications in gait training procedures for impaired populations designed to reduce tripping risk.