Postural stability after treadmill and overground walking in young and elderly

Estimating highest capacity propulsion performance using backward-directed force during walking evaluation for individuals with acquired brain injury

There are over 5.3 million Americans who face acquired brain injury (ABI)-related disability as well as almost 800,000 who suffer from stroke each year. To improve mobility and quality of life, rehabilitation professionals often focus on walking recovery soon after hospital discharge for ABI. Reduced propulsion capacity (force output of the lower limbs to counteract ground reaction forces) negatively impacts walking ability and complicates recovery during rehabilitation for brain injured people. We describe a method, using backward-directed resistance (BDR) in a robotic-based treadmill device, to allow measurement of maximum walking propulsion force (MWPF) that is not otherwise possible during overground walking assessment. Our objective was to test the construct validity of a maximum walking propulsion force (MWPF) measure that reflects a person's propulsive strength against applied BDR, while walking on a robotic treadmill-based device for participants with acquired brain injury (ABI). Our study enrolled 14 participants with ABI at an in inpatient rehabilitation in Galveston, TX from 8/1/21 - 4/31/22. The range of weight-adjusted MWPF was 2.6-27.1% body weight (%BW), mean 16.5 ± 8.4%BW, reflecting a wide range of propulsive force capability. The strongest correlation with overground tests was between the 6-minute walk test (6-MWT) distance and the MWPF values (r = 0.83, p < 0.001) with moderate correlations between the 10-meter walk tests at comfortable (CWS) and fast speeds (FWS). The Five Times Sit-to-Stand (used as a standard clinical measure of functional lower extremity strength) and MWPF tests were poorly correlated (r = 0.26, p = 0.4). Forward model selection included 6-MWT distance, age, and overground CWS as significant partial predictors of MWPF. We conclude that this novel MWPF measure is a valid representation of maximum propulsive force effort during walking for people post-ABI. Additional research could help determine the impact of interventions designed to increase propulsive force generation during rehabilitation training to improve overground walking performance.

A neuromusculoskeletal modelling approach to bilateral hip mechanics due to unexpected lateral perturbations during overground walking

BACKGROUND

Current studies on how external perturbations impact gait dynamics have primarily focused on the changes in the body's center of mass (CoM) during treadmill walking. The biomechanical responses, in particular to the multi-planar hip joint coordination, following perturbations in overground walking conditions are not completely known.

METHODS

In this study, a customized gait-perturbing device was designed to impose controlled lateral forces onto the subject's pelvis during overground walking. The biomechanical responses of bilateral hips were simulated by subject-specific neuromusculoskeletal models (NMS) driven by in-vivo motion data, which were further evaluated by statistical parameter mapping (SPM) and muscle coactivation index (CI) analysis. The validity of the subject-specific NMS was confirmed through comparison with measured surface electromyographic signals.

RESULTS

Following perturbations, the sagittal-plane hip motions were reduced for the leading leg by 18.39° and for the trailing leg by 8.23°, while motions in the frontal and transverse plane were increased, with increased hip abduction for the leading leg by 10.71° and external rotation by 9.06°, respectively. For the hip kinetics, both the bilateral hip joints showed increased abductor moments during midstance (20%-30% gait cycle) and decreased values during terminal stance (38%-48%). Muscle CI in both sagittal and frontal planes was significantly decreased for perturbed walking (p < 0.05), except for the leading leg in the sagittal plane.

CONCLUSION

The distinctive phase-dependent biomechanical response of the hip demonstrated its coordinated control strategy for balance recovery due to gait perturbations. And the changes in muscle CI suggested a potential mechanism for rapid and precise control of foot placement through modulation of joint stiffness properties. These findings obtained during actual overground perturbation conditions could have implications for the improved design of wearable robotic devices for balance assistance.

Is treadmill walking biomechanically comparable to overground walking? A systematic review

BACKGROUND

The equivalency of treadmill and overground walking has been investigated in a large number of studies. However, no systematic review has been performed on this topic.

RESEARCH QUESTION

The aim of this study was to compare the biomechanical, electromyographical and energy consumption outcomes of motorized treadmill and overground walking.

METHODS

Five databases, ScienceDirect, SpringerLink, Web of Science, PubMed, and Scopus, were searched until January 13, 2021. Studies written in English comparing lower limb biomechanics, electromyography and energy consumption during treadmill and overground walking in healthy young adults (20-40 years) were included.

RESULTS

Twenty-two studies (n = 409 participants) were included and evaluated via the Cochrane Collaboration's tool. These 22 studies showed that some kinematic (reduced pelvic ROM, maximum hip flexion angle for females, maximum knee flexion angle for males and cautious gait pattern), kinetic (sagittal plane joint moments: dorsiflexor moments, knee extensor moments and hip extensor moments and sagittal plane joint powers at the knee and hip joints, peak backwards, lateral and medial COP velocities and propulsive forces during late stance) and electromyographic (lower limbs muscles activities) outcome measures were significantly different for motorized treadmill and overground walking.

SIGNIFICANCE

Spatiotemporal, kinematic, kinetic, electromyographic and energy consumption outcome measures were largely comparable for motorized treadmill and overground walking. However, the differences in kinematic, kinetic and electromyographic parameters should be taken into consideration by clinicians, trainers, and researchers when working on new protocols related to patient rehabilitation, fitness rooms or research as to be as close as possible to the outcome measures of overground walking. The protocol registration number is CRD42021236335 (PROSPERO International Prospective Register of Systematic Reviews).

Holographic Sight Improves the Static Shooting Accuracy and Vertical Sway Precision During High-Intensity Dynamic Action in the Police Task Force

The aim of this study was to find the effect of holographic sight (HS) on short-distance shooting accuracy and precision during static and high-intensity dynamic actions. Twenty policemen (31 ± 2.2 years, 85.6 ± 6.1 kg, and 181.9 ± 4.4 cm) performed five shots in the 10-s limit under the static condition for 20 m and dynamic condition 15-5 m, and after 4 × 10 m sprint action, both with fixed sight (FS) and HS. The analysis of variance post hoc test revealed that HSstatic had higher shouting accuracy than FSstatic, FSdynamic, and HSdynamic (p = .03, p = .0001, and p = .0001, respectively) and FSdynamic had lower precision than FSstatic, HSstatic, and HSdynamic (p = .0003, p = .0001, and p = .01, respectively) in vertical sway. The HS for rifles has improved the accuracy of static shooting and vertical sway precision of dynamic shooting.