Temporal variability in the phase durations during treadmill walking

BACKGROUND: Current exercise guidelines for older adults recommend at least 30 min of physical activity (PA) on most days of the week (≥4/wk) performed at 55-90% of maximum heart rate (HRmax). While the recommended frequency and duration of PA can be easily self-selected, it is unclear if older adults are able to select the recommended exercise intensity. PURPOSE: To determine if healthy women (65 - 74 yr) are able to self-select a walking intensity that is within the current recommendations for daily PA during treadmill (TM) and over-ground (OG) walking. METHODS: Nine healthy older women (age = 68.5 ± 3.2 yr, BMI = 26.2 ± 5.7 kg/m2, peak O2 uptake (VO2peak) = 22.7 ± 4.7 mL/kg/min) performed four, 30-min walking trials (two TM and two OG) in a counterbalanced, randomized order. For the initial TM and OG trials, subjects self-selected their walking speed. Walking speed, heart rate (HR) and ratings of perceived exertion (RPE) were recorded during these trials. For the second TM and OG trials, walking speed was controlled to match the speeds selected during the initial TM and OG trials. During the second TM and OG trials, pulmonary gas exchange was measured using a COSMED K4b2, in addition to HR and RPE. RESULTS: Exercise intensity during self-selected TM and OG walking were within the current guidelines for daily PA (TM = 70% HRmax, 95%CI = 66 - 75%; OG = 73% HRmax, 95%CI = 67 - 79%). Differences in the HR and VO2 responses for TM and OG walking were not significant (%HRmax, p =.06; %VO2peak, p =.08), while walking speed during OG was significantly greater than TM walking (p =.01). CONCLUSION: Healthy older women are able to self-select a walking intensity that is suitable for meeting the current recommendations for daily PA during both TM and OG walking. This project is Supported by the National Health and Medical Research Council of Australia.

BackgroundAbout one-third of people older than 65 years fall at least once a year. Physical exercise has been previously demonstrated to improve gait, enhance physical fitness, and prevent falls. Nonetheless, the addition of cognitive training components may potentially increase these effects, since cognitive impairment is related to gait irregularities and fall risk. We hypothesized that simultaneous cognitive–physical training would lead to greater improvements in dual-task (DT) gait compared to exclusive physical training.MethodsElderly persons older than 70 years and without cognitive impairment were randomly assigned to the following groups: 1) virtual reality video game dancing (DANCE), 2) treadmill walking with simultaneous verbal memory training (MEMORY), or 3) treadmill walking (PHYS). Each program was complemented with strength and balance exercises. Two 1-hour training sessions per week over 6 months were applied. Gait variables, functional fitness (Short Physical Performance Battery, 6-minute walk), and fall frequencies were assessed at baseline, after 3 months and 6 months, and at 1-year follow-up. Multiple regression analyses with planned comparisons were carried out.ResultsEighty-nine participants were randomized to three groups initially; 71 completed the training and 47 were available at 1-year follow-up. DANCE/MEMORY showed a significant advantage compared to PHYS in DT costs of step time variability at fast walking (P=0.044). Training-specific gait adaptations were found on comparing DANCE and MEMORY: DANCE reduced step time at fast walking (P=0.007) and MEMORY reduced gait variability in DT and DT costs at preferred walking speed (both trend P=0.062). Global linear time effects showed improved gait (P<0.05), functional fitness (P<0.05), and reduced fall frequency (−77%, P<0.001). Only single-task fast walking, gait variability at preferred walking speed, and Short Physical Performance Battery were reduced at follow-up (all P<0.05 or trend).ConclusionLong-term multicomponent cognitive–physical and exclusive physical training programs demonstrated similar potential to counteract age-related decline in physical functioning.

While vision obviously plays an essential role in orienting and obstacle avoidance, its role in the regulation of dynamic balance is not yet fully understood. The objective of this study was to assess dynamic stability while blindfolded, under optimal conditions that minimized the fear of falling. The hypothesis was that visual deprivation could be compensated for by using other sensory strategies to stabilize gait. One hundred healthy adults (aged 20-69 years) participated in the study. They were previously accustomed to blindfolded treadmill walking wearing a safety harness. Their preferred walking speeds (PWS) were assessed with eyes open (PWSEO) and with eyes closed (blindfolded, PWSEC). Three five-minute tests were performed: (A) normal walking at PWSEO, (B) blindfolded walking at PWSEC, and (C) normal walking at PWSEC. Trunk acceleration was measured with a lightweight inertial sensor. Dynamic stability was assessed by using (1) acceleration root mean square (RMS), which estimates the variability of the signal, and hence, the smoothness of the trunk movement and (2) local dynamic stability (LDS), which reflects the efficiency of the motor control to stabilize the trunk. Although walking at PWSEC with eyes open (comparing conditions A and C) had a slight impact on gait stability (relative difference: RMS +4 %, LDS -5 %), no destabilizing effect of visual deprivation (B vs. C, RMS -4 %, LDS -1 %) was observed. Therefore, it is concluded that when reassuring conditions are offered to individuals while walking, they are able to adopt alternative sensory strategies to control dynamic equilibrium without the help of vision.

Alterations in muscle activation patterns during robotic-assisted walking

Increased stride time variability has been associated with memory impairment in mild cognitive impairment. Subjective memory impairment (SMI) is considered the earliest clinical stage of Alzheimer's disease (AD). The association between increased stride time variability and SMI has not been reported. This study aims to examine the association of stride time variability while performing single and dual tasking with SMI in cognitively healthy individuals (CHI). A total of 126 CHI (15 without SMI, 69 with SMI expressed by participants, 10 with SMI expressed by participant's relative, and 32 with SMI expressed by both participants and their relatives) were included in this cross-sectional study. The coefficient of variation (CoV) of stride time and walking speed were recorded under usual condition and while counting backwards. Age, gender, body mass index, number of drugs taken daily, use of psychoactive drugs, fear of falling, history of previous falls, and walking speed were used as covariates. The multiple linear regression models showed that greater CoV of stride time while counting backwards, but not while single tasking, was associated with a participant's relative SMI (p = 0.038). This study found a specific association between SMI expressed by a participant's relative and a greater CoV of stride time (i.e., worse performance) while dual tasking, suggesting that the association between gait variability and memory may be present in the earliest stages of memory impairment. Thus, gait variability under dual-task in individuals with SMI expressed by their relatives can be a potential biomarker of AD.

BACKGROUND Exergame balance training, which integrates cognitive and motor challenges, may enhance neuroplasticity, postural control, and gait stability in adults with mild cognitive impairment (MCI). Varying task difficulty can modulate cognitive load, potentially influencing motor adaptation and functional mobility. OBJECTIVE This study aimed to compare improvement in balance and gait parameters across variable-difficulty exergame training and a Wii Fit group in adults with MCI. METHODS This four-armed, parallel design, randomized clinical trial included 97 participants with MCI (MoCA 18-25), randomly assigned to one of four groups: mild-difficulty, moderate-difficulty, high-difficulty exergame training, or a Wii Fit group. Each participant completed 24 sessions (40 minutes per session, three times per week). Gait and Balance were assessed using Time Up and Go (TUG), Cognitive Time Up and Go (C-TUG), and the Gait&amp;Balance mobile app at the baseline. 4 weeks, and 8 weeks. Mixed models analysis of covariance (ANCOVA), with baseline values as a covariate, was used to assess interaction effects between interventions and time. Post hoc ANCOVA was conducted to analyze the between-group differences. RESULTS High-difficulty training resulted in the greatest improvements in TUG (-0.71±0.32, p&lt;0.028), anteroposterior (AP) steadiness with eyes open (EO) on a firm surface (0.04±0.02, p=0.039), step time variability with head forward (HF) (0.06±0.09, p=0.020) walking speed HF (0.08±0.04, p=0.050), step time head turn (HT) (-0.04±0.02,p= 0.042), step time variability HT (-0.35±0.09, p&lt;0.001), step length variability (-0.27±0.13,p=0.039)and walking speed HT (0.09±0.04,p=0.008) compared to the Wii Fit group. Moderate-difficulty training showed significant improvements in AP steadiness with EO on a firm surface (0.05±0.02, p=0.029) and reduced step time variability HT (-0.26±0.09, p=0.007). Mild-difficulty training improved C-TUG (-1.61±0.63, p&lt;0.013), AP steadiness with a firm EO surface (0.05±0.02, p=0.029), step time variability HF (-0.20±0.09, p=0.027), step time variability HT (-0.25±0.09, p&lt;0.008), step length variability (-0.31±0.12, p=0.014) and walking speed HT (0.11±0.04, p=0.028). No significant differences were observed between the exergame difficulty groups (p&gt; 0.05). CONCLUSIONS Cognitive-motor challenging exergame balance training significantly improved balance and gait parameters in adults with MCI. While no significant differences were found between the different difficulty levels. However, high-difficulty and mild-difficulty training showed greater improvements compared to the Wii Fit group. High-difficulty training led to superior enhancements in TUG performance, postural steadiness, gait variability, and walking speed. These findings suggest that difficulty-based exergames can be an effective intervention for improving postural control and walking stability in individuals with MCI, with potential implications for fall prevention and mobility maintenance in aging populations. CLINICALTRIAL ClinicalTrials.gov NCT04959383

This study was designed to determine whether patients with peripheral vascular disease (PVD) have gait abnormalities. A previous study on humans with PVD found no abnormalities whereas significant gait changes were seen with a rat model of PVD. The study population was comprised of 10 controls and 9 subjects with PVD (all male). The PVD group had documented pain in one or both legs while walking. Subjects ranged in age from 55-92 years of age, with a mean age of 69 in the PVD group and 70 in the control group. The GaitMat II system was used to measure both spatial and temporal variables of gait. Subjects walked across the mat, four to six times, at their comfortable walking speed. The PVD group then walked on a treadmill until they experienced moderate claudication pain and felt they had to stop (pain levels between 6 and 8, with maximal pain at level 10). Control group walked on a treadmill for 10 minutes without pain. All subjects repeated the gait tests on the GaitMat H system immediately after treadmill walking. Claudication pain persisted in the PVD group during the second gait test. The PVD group was not different than control group in any of the measured variables on the first test (p values from .35 to .99). Difference scores (post- minus pre-treadmill walking)for PVD group were significantly different than those for control group on 8 of 11 variables (p values <.005). The primary response in PVD subjects was reduced walking speed (1.02+/-0.16 to 0.94+/-0.16 m/s) and reduced step length (0.60+/-0.08 to 0.57+/-0.09 m/s), whereas control subjects increased their speed (1.09+/-0.17 to 1.19+/-0.19 m/s) and step length (0.63+/-0.10 to 0.67+/-0.10 m/s). No asymmetries in gait were measured in either group, either before or after treadmill walking. In conclusion, PVD subjects were not different in gait while rested, but responded to claudication pain by reducing preferred walking speed and step size.

Effects of age and walking speed on long-range autocorrelations and fluctuation magnitude of stride duration

Background: It has been suggested that high stride-to-stride variability (STV) is a reflection of gait instability. However, both low and high STV has been shown in fallers and in nonfallers; therefore, the interpretation of STV of spatiotemporal gait parameters remains difficult. Thus, we sought to characterize and compare STV of spatial and temporal stride parameters among young and older healthy adults, and to determine the extent to which opposite results in STV could provide similar implications in terms of gait stability. Methods: Mean values of coefficients of variation of spatiotemporal gait parameters were collected from 30 young adults (14 men and 16 women; mean age 28.1 ± 6.0 years) and 33 older adults (2 men and 31 women; mean age 74.4 ± 7.1 years) walking at self-chosen normal walking speed over a GAITRite® System. Results: An age-related increase in STV was only observed with stride width (p = 0.012), whereas increased stride length and stance time variability in older adults were related to decreased walking speed (p = 0.006 and p = 0.018). In addition, both low and high STV was found in both groups of subjects and the highest value was observed for stride width (p < 0.001). Conclusion: The two main implications of the present results are that decreased walking speed should be taken into account when exploring age-related effects on gait variability, and that both low and high spatiotemporal STV may reflect gait stability in healthy adults.

Walking energy expenditure, calculated as the percent utilization of the maximal aerobic capacity, is little investigated in transfemoral amputees. Compare the energy expenditure of healthy participants (control participants) and transfemoral amputees walking with their respective preferred walking speeds on the treadmill (TPWS) and floor (FPWS). Randomized cross-over study. Oxygen uptake (VO2) was measured when walking with the FPWS and TPWS. VO2max was measured by an incremental treadmill test. Mean ± standard deviation VO2max of the transfemoral amputees and control participants were 30.6 ± 8.7 and 49.0 ± 14.4 mL kg(-1) min(-1), respectively (p < 0.05). TPWS for the transfemoral amputees and control participants was 0.89 ± 0.2 and 1.33 ± 0.3 m s(-1), respectively (p < 0.01). FPWS for the transfemoral amputees and control participants was 1.22 ± 0.2 and 1.52 ± 0.1 m s(-1), respectively (p < 0.01). Walking on floor with the FPWS, the energy expenditure of the transfemoral amputees and control participants was 54% and 31% of VO2max, respectively (p < 0.01). Walking on the treadmill with the TPWS, the energy expenditure of the transfemoral amputees and control participants was 42% and 29% of the VO2max, respectively (p < 0.05). Energy expenditure is higher for the transfemoral amputees than the control participants, regardless of walking surface. There are minimal differences in energy expenditure between treadmill and floor walking for the control participants but large differences for the transfemoral amputees. During walking, the transfemoral amputees expend a larger percentage of their maximal aerobic capacity than healthy participants. With a low VO2max, ordinary activities, such as walking, become physically more challenging for the transfemoral amputees than the control participants, and this may, in turn, have a negative effect on the walking range of the transfemoral amputees.

Introduction: Walking speed can affect gait stability and increase the risk of falling.Methods: In this study, we design a device to measure the distribution of the plantar pressure to investigate the impact of the walking speed on the stability of the human gait and movements of the body. We fused the entropy acquired at multiple scales with signals of the plantar pressure to evaluate the effects of the walking speed on the stability of the human gait. We simultaneously collected data on the motion-induced pressure from eight plantar regions to obtain the fused regional pressure. To verify their accuracy, we obtained data on the plantar pressure during walking by using the force table of the Qualisys system. We then extracted the peak points and intervals of the human stride from pressure signals fused over three regions, and analyzed the mechanics of their regional fusion by using the regional amplitude–pressure ratio to obtain the distribution of the plantar pressure at an asynchronous walking speed. Furthermore, we introduced multi-scale entropy to quantify the complexity of the gait and evaluate its stability at different walking speeds.Results: The results of experiments showed that increasing the speed from 2 to 6 km/h decreased the stability of the gait, with a 26.7% increase in the amplitude of pressure in the region of the forefoot. The hindfoot and forefoot regions were subjected to the minimal pressure at a speed of 2 km/h, while the most consistent stress was observed in regions of the forefoot, midfoot, and hindfoot. Moreover, the curve of entropy at a speed of 2 km/h exhibited a slow decline at a small scale and high stability at a large scale.Discussion: The multi-scale entropy increased the variation in the stability of the synchronous velocity of walking compared with the sample entropy and the analysis of regional fusion mechanics. Multi-scale entropy can thus be used to qualitatively assess the relationship between the speed and stability of the gait, and to identify the most stable gait speed that can ensure gait stability and posture control.

541 THE IMPACT OF INTRA-ARTICULAR HYALURONIC ACID ON GAIT VARIABILITY IN KNEE OSTEOARTHRITIS PATIENTS

Effect of walking speed and severity of hip osteoarthritis on gait variability

Test-retest reliability and variability of self-reported normal treadmill walking speeds in adults aged 20-80 years old.

Supported Treadmill Ambulation for Amyotrophic Lateral Sclerosis: A Pilot Study