Plug-in-Gait calculation of the knee adduction moment in people with knee osteoarthritis during shod walking: comparison of two different foot marker models

Increased trial-to-trial similarity and reduced temporal overlap of muscle synergy activation coefficients manifest during learning and with increasing movement proficiency

Muscle synergy analyses are used to enhance our understanding of motor control. Spatially fixed synergy weights coordinate multiple co-active muscles through activation commands, known as activation coefficients. To gain a more comprehensive understanding of motor learning, it is essential to understand how activation coefficients vary during a learning task and at different levels of movement proficiency. Participants walked on a line, a beam, and learned to walk on a tightrope-tasks that represent different levels of proficiency. Muscle synergies were extracted from electromyography signals across all conditions and the number of synergies was determined by the knee-point of the total variance accounted for (tVAF) curve. The results indicated that the tVAF of one synergy decreased with task proficiency, with the tightrope task resulting in the highest tVAF compared to the line and beam tasks. Furthermore, with increasing proficiency and after a learning process, trial-to-trial similarity increased and temporal overlap of synergy activation coefficients decreased. Consequently, we propose that precise adjustment and refinement of synergy activation coefficients play a pivotal role in motor learning.

Standard isometric contraction has higher reliability than maximum voluntary isometric contraction for normalizing electromyography during level walking among older adults with knee osteoarthritis

Introduction: Electromyography (EMG) normalization often relies on maximum voluntary isometric contraction (MVIC), which may not be suitable for knee osteoarthritis (KOA) patients due to difficulties in generating maximum joint torques caused by pain. This study aims to assess the reliability of standard isometric contraction (SIC) for EMG normalization in older adults with KOA, comparing it with MVIC. Methods: We recruited thirty-five older adults with KOA and collected root mean square EMG amplitudes from seven muscles in the affected limb during level walking, SIC, and MVIC tests. EMG data during level walking were normalized using both SIC and MVIC methods. This process was repeated after at least 1 week. We calculated intra-class correlation coefficients (ICCs) with 95% confidence intervals to evaluate between- and within-day reliabilities. Results: SIC tests showed higher between- (ICC: 0.75-0.86) and within-day (ICC: 0.84-0.95) ICCs across all seven muscles compared to MVIC tests. When normalized with SIC, all seven muscles exhibited higher between- (ICC: 0.67-0.85) and within-day (ICC: 0.88-0.99) ICCs compared to MVIC normalization. Conclusion: This study suggests that SIC may offer superior movement consistency and reliability compared to MVIC for EMG normalization during level walking in older adults with KOA.

Racewalking on a treadmill alters gait characteristics without increasing risk of disqualification

PURPOSE

Treadmill training is useful for racewalking training; however, it may affect gait characteristics and lead to non-legal techniques. The aim of this study was to determine the kinematic differences between treadmill and overground conditions during racewalking at different speeds.

METHODS

Twenty-two elite racewalkers participated in this study. They racewalked under treadmill and overground conditions at high and medium speeds. A 12-camera motion analysis system was used to record the racewalking trials.

RESULTS

Significant condition by speed interactions were detected in step frequency and pelvis rotation angle; step frequency decreased while pelvis rotation angle increased from overground to treadmill conditions at high speed. Compared to overground conditions, racewalkers decreased the ankle dorsiflexion angle at heel strike and increased hip flexion, shoulder hyperextension, and elbow flexion angles at heel strike and hip and shoulder extension angles at toe-off under treadmill conditions. Compared to medium speed, racewalkers decreased the contact time, hip flexion, and shoulder hyperextension at heel strike, and ankle plantarflexion and shoulder extension angles at toe-off, and increased flight time, step length, and elbow flexion angle at heel strike at high speed.

CONCLUSION

Several kinematic differences during racewalking were detected between treadmill and overground conditions, with more differences detected at high speed, indicating that treadmill racewalking, especially at high speed, has different gait characteristics. However, no differences were detected in flight time and knee angle under treadmill conditions compared to overground conditions, indicating that racewalking on a treadmill does not increase the risk of disqualification.

Do different multi-segment foot models detect the same changes in kinematics when wearing foot orthoses?

Background

Different multi-segment foot models have been used to explore the effect of foot orthoses. Previous studies have compared the kinematic output of different multi-segment foot models, however, no study has explored if different multi-segment foot models detect similar kinematic changes when wearing a foot orthoses. The aim of this study was to compare the ability of two different multi-segment foot models to detect kinematic changes at the hindfoot and forefoot during the single and double support phases of gait when wearing a foot orthosis.

Methods

Foot kinematics were collected during walking from a sample of 32 individuals with and without a foot orthosis with a medial heel bar using an eight-camera motion capture system. The Oxford Foot Model (OFM) and a multi-segment foot model using the Calibrated Anatomical System Technique (CAST) were applied simultaneously. Vector field statistical analysis was used to explore the kinematic effects of a medial heel bar using the two models, and the ability of the models to detect any changes in kinematics was compared.

Results

For the hindfoot, both models showed very good agreement of the effect of the foot orthosis across all three anatomical planes during the single and double support phases. However, for the forefoot, the level of agreement between the models varied with both models showing good agreement of the effect in the coronal plane but poorer agreement in the transverse and sagittal planes.

Conclusions

This study showed that while consistency exists across both models for the hindfoot and forefoot in the coronal plane, the forefoot in the transverse and sagittal planes showed inconsistent responses to the foot orthoses. This should be considered when interpreting the efficacy of different interventions which aim to change foot biomechanics.

Proprioceptive Neuromuscular Facilitation Improves Symptoms Among Older Adults With Knee Osteoarthritis During Stair Ascending: A Randomized Controlled Trial

OBJECTIVE

This study aimed to investigate the effects of a 6-wk proprioceptive neuromuscular facilitation stretching on pain, proprioception, joint range of motion, and joint moments during stair ascending among older adults with knee osteoarthritis.

DESIGN

This study is a randomized, controlled, and assessor-blinded trial. Thirty-six older adults with knee osteoarthritis were randomly assigned to the proprioceptive neuromuscular facilitation and the control groups. They received proprioceptive neuromuscular facilitation stretching and health lecture series, respectively, for 6 wks. Final data analysis included 14 participants of the proprioceptive neuromuscular facilitation group and 13 of the control group. Pain score, joint proprioception, range of motion, and joint moments during stair ascending were measured before and after the stretching. Two-way (group by time) analysis of variance with repeated measures was used to evaluate stretching effects.

RESULTS

Significant interactions were detected in pain score, joint proprioception, external knee adduction moment, and external knee extension moment. Compared with week 0, the pain score, joint proprioception threshold, and external knee adduction moment decreased, whereas the external knee extension moment increased among older adults in the proprioceptive neuromuscular facilitation group at week 7.

CONCLUSIONS

Proprioceptive neuromuscular facilitation could be recommended as one of the clinical treatments for knee osteoarthritis to relieve pain, improve proprioception, and balance load distribution between medial and lateral compartments at the knee.

A novel walking cane with haptic biofeedback reduces knee adduction moment in the osteoarthritic knee

Knee osteoarthritis is a leading cause of ambulatory disability in adults. The most prescribed mobility aid, the walking cane, is often underloaded and therefore fails to reduce knee joint loading and provide symptomatic relief. For this study, a novel walking cane with haptic biofeedback was designed to improve cane loading and reduce the knee adduction moment (KAM). To determine; 1) the short-term efficacy of a novel walking cane using haptic biofeedback to encourage proper cane loading and 2) the effects of the novel cane on KAM. Cane loading and KAM, peak knee adduction moment (PKAM), and knee adduction angular impulse (KAAI)) while walking were calculated under five conditions: 1) naïve, 2A) after scale training (apply 20%BW to cane while standing, using a beam scale), 2B) scale recall (attempt to load the cane to 20%BW), 3A) after haptic training (vibrotactile biofeedback delivered when target cane load achieved), and 3B) haptic recall (attempt to load the cane to 20%BW with vibrotactile biofeedback delivered). Compared to the naïve condition all interventions significantly increased cane loading and reduced PKAM and KAAI. No differences between haptic recall and scale recall condition were observed. The haptic biofeedback cane was shown to be an effective and simple way to increase cane loading and reduced knee loading. Haptic biofeedback and scale training were equally effective at producing immediate short-term improvements in cane loading and knee loading. Future studies should examine the long-term effects of scale training and canes with haptic biofeedback on knee joint health, pain, and osteoarthritis disease progression.

Limb movement, coordination and muscle activity during a cross-coordination movement on a stable and unstable surface

BACKGROUND

At a clinical level, the intensity of dynamic balance tasks incorporating cross-coordination movements (CCM) is typically progressed by changing the stability of the support surface on which the movement is undertaken. However, biomechanical changes in CCMs performed on stable and unstable surfaces have not yet been quantified.

RESEARCH QUESTION

Do movement patterns, muscle activity, coordination strategies, knee joint loading and center of mass (CoM) movement differ during a CCM performed on stable and unstable surfaces?

METHODS

Motion analysis was used to monitor limb kinematics and surface electromyography to analyze supporting leg muscle activity in sixteen healthy athletes during a single-limb support task involving a cyclic CCM on a stable and unstable surface. Angle-angle plots were used to explore coordination strategies in sagittal movement of the hip and shoulder, while differences in kinematics and muscle activity between stable and unstable conditions were evaluated using dependent t-tests (α-level = 0.05).

RESULTS

CCMs on an unstable surface were performed at a slower speed (p < .05), with a more flexed posture of the support knee (p < .05) and ankle (p < .05) and resulted in reduced hip and shoulder movement of the swing limbs (p < .05). Instability increased activation of selected muscles of the ankle and knee (p < .05), resulted in a two-fold increase in the peak knee adduction moment (p < .05), and was accompanied by greater CoM movement (p < .05). Three coordination patterns of the swing limbs observed when performing CCM on a stable surface, which were mostly preserved on the unstable surface.

SIGNIFICANCE

Despite adopting several stabilization strategies, CCM undertaken on an unstable surface still evoked greater excursion of the center of mass and, as such, presented a greater challenge to sensorimotor control. Adding instability in form of a swinging platform provides progression of dynamic balance CCM difficulty in an athletic population.

The effect of walking speed on the foot inter-segment kinematics, ground reaction forces and lower limb joint moments

Background

Normative foot kinematic and kinetic data with different walking speeds will benefit rehabilitation programs and improving gait performance. The purpose of this study was to analyze foot kinematics and kinetics differences between slow walking (SW), normal walking (NW) and fast walking (FW) of healthy subjects.

Methods

A total of 10 healthy male subjects participated in this study; they were asked to carry out walks at a self-selected speed. After measuring and averaging the results of NW, the subjects were asked to perform a 25% slower and 25% faster walk, respectively. Temporal-spatial parameters, kinematics of the tibia (TB), hindfoot (HF), forefoot (FF) and hallux (HX), and ground reaction forces (GRFs) were recorded while the subjects walked at averaged speeds of 1.01 m/s (SW), 1.34 m/s (NW), and 1.68 m/s (FW).

Results

Hindfoot relative to tibia (HF/TB) and forefoot relative to hindfoot (FF/HF) dorsiflexion (DF) increased in FW, while hallux relative to forefoot (HX/FF) DF decreased. Increased peak eversion (EV) and peak external rotation (ER) in HF/TB were observed in FW with decreased peak supination (SP) in FF/HF. GRFs were increased significantly with walking speed. The peak values of the knee and ankle moments in the sagittal and frontal planes significantly increased during FW compared with SW and NW.

Discussion

Limited HF/TB and FF/HF motion of SW was likely compensated for increased HX/FF DF. Although small angle variation in HF/TB EV and FF/HF SP during FW may have profound effects for foot kinetics. Higher HF/TB ER contributed to the FF push-off the ground while the center of mass (COM) progresses forward in FW, therefore accompanied by higher FF/HF abduction in FW. Increased peak vertical GRF in FW may affected by decreased stance duration time, the biomechanical mechanism maybe the change in vertical COM height and increase leg stiffness. Walking speed changes accompanied with modulated sagittal plane ankle moments to alter the braking GRF during loading response. The findings of foot kinematics, GRFs, and lower limb joint moments among healthy males may set a reference to distinguish abnormal and pathological gait patterns.