Effect of a 4-week static stretching program for plantar flexor muscles on physical performance and muscle properties

BACKGROUND: The effects of a long-term static stretching program on physical performance parameters have not been elucidated completely, although the effects on muscle flexibility have a consensus. OBJECTIVE: This study aimed to investigate the effect of a long-term static stretching program on physical performance and muscle properties. METHODS: Participants performed a 2-min static stretching for the ankle joint 5 times per week for 4 weeks. Physical performance and muscle properties was measured before and after the static stretching program. RESULTS: Results showed that range of motion (ROM), dynamic postural stability, and muscle hardness were positively changed, whereas other variables i.e. maximal isometric plantar flexion moment, jump heights, muscle-tendon junction displacement and its angle, were not. CONCLUSIONS: Four-week of SS program may improve ROM, dynamic postural stability, and muscle hardness without decreasing physical performance.

Do Athletes With a Reconstructed Anterior Cruciate Ligament Respond Differently Than Controls to Visual Challenges When Dynamic Postural Stability is Assessed?

Individuals returning to sport after anterior cruciate ligament reconstruction (ACLR) are at an increased risk of sustaining a subsequent ACL injury. It is suspected that increased reliance on visual information to maintain stability may factor into this increased risk. The connection between visual reliance and ACLR is not well understood during dynamic tasks. Examination of the proposed visual reliance may help improve returning to sport standards and reduce subsequent ACL injury risk. A total of 12 ACLR individuals and 12 age- and sex-matched controls completed several trials of a normalized dynamic hop task on both limbs under 3 different visual conditions (eyes open, low visual disruption, and high visual disruption). Stroboscopic eyewear were worn by each participant to disrupt vision during testing. Ground reaction force data were collected during landing. Dynamic postural stability was assessed using 2 separate calculations: dynamic postural stability index and time to stability. No significant statistical interactions or group differences were observed. The stroboscopic eyewear did increase the medial–lateral stability index from the eyes open to the low visual disruption condition (P < .05). These findings suggest that ACLR individuals do not rely on visual information more than controls during a dynamic hop task.

Reliability and usefulness of the single leg heel raise balance test in patients with chronic ankle instability

We aimed to analyze the differences in static (including conventional and modified [single-leg heel-raise balance]) and dynamic postural stability and muscle endurance between patients with chronic ankle instability (CAI) and healthy controls, and to determine the reliability and usefulness of the single-leg heel-raise balance test in patients with CAI. In total, 26 patients with CAI and 26 healthy controls were enrolled. Postural stability was assessed using a postural stabilometry system. Muscle endurance was measured in dorsiflexion and plantarflexion using an isokinetic device. Modified static postural stability (P < 0.001) and dynamic postural stability (P < 0.001) were significantly poorer in the affected ankles of patients with CAI than in the controls. Plantarflexion endurance was significantly lower in the affected ankles of the patients with CAI than in the controls (P = 0.023). Modified static postural stability significantly correlated with plantarflexion endurance in both groups (CAI group: r = − 0.470, P = 0.015; healthy controls group: r = − 0.413, P = 0.036). Plantarflexion endurance was a significant risk factor for modified static postural stability in both the CAI group (R2 = 0.221, P = 0.015) and healthy controls (R2 = 0.170, P = 0.036). Given the reliability of the modified static postural stability test, clinicians and therapists should consider using it to assess improvements in postural stability and muscle endurance in patients with CAI before and after rehabilitation.

Low-frequency STN-DBS provides acute gait improvements in Parkinson’s disease: a double-blinded randomised cross-over feasibility trial

Background Some people with Parkinson’s disease (PD) report poorer dynamic postural stability following high-frequency deep brain stimulation of the subthalamic nucleus (STN-DBS), which may contribute to an increased falls risk. However, some studies have shown low-frequency (60 Hz) STN-DBS improves clinical measures of postural stability, potentially providing support for this treatment. This double-blind randomised crossover study aimed to investigate the effects of low-frequency STN-DBS compared to high-frequency stimulation on objective measures of gait rhythmicity in people with PD. Methods During high- and low-frequency STN-DBS and while off-medication, participants completed assessments of symptom severity and walking (e.g., Timed Up-and-Go). During comfortable walking, the harmonic ratio, an objective measures of gait rhythmicity, was derived from head- and trunk-mounted accelerometers to provide insight in dynamic postural stability. Lower harmonic ratios represent less rhythmic walking and have discriminated people with PD who experience falls. Linear mixed model analyses were performed on fourteen participants. Results Low-frequency STN-DBS significantly improved medial–lateral and vertical trunk rhythmicity compared to high-frequency. Improvements were independent of electrode location and total electrical energy delivered. No differences were noted between stimulation conditions for temporal gait measures, clinical mobility measures, motor symptom severity or the presence of gait retropulsion. Conclusions This study provides evidence for the acute benefits of low-frequency stimulation for gait outcomes in STN-DBS PD patients, independent of electrode location. However, the perceived benefits of this therapy may be diminished for people who experienced significant tremor pre-operatively, as lower frequencies may cause these symptoms to re-emerge. Trial registration: This study was prospectively registered with the Australian and New Zealand Clinical Trials Registry on 5 June 2018 (ACTRN12618000944235).

Effects of a Biomechanical-based Tai Chi Program on Gait and Posture in People With Parkinson’s Disease: Study Protocol for a Randomized Controlled Trial

BackgroundParkinson’s disease (PD) is associated with changes in gait and posture that can lead to a higher frequency of falls and injuries in this population. Research has shown a positive effect of tai chi (TC) training on the movement capacity for those with PD, however the understanding of the impact of TC training on gait and postural stability in PD is lacking. This study aims to examine the impact of a biomechanical-based TC training on dynamic postural stability and how it relates to walking performance.Methods/DesignWe will conduct a prospective, single-blind, randomized control trial of 40 individuals with early-stage PD (Hoehn & Yahr stages 1 to 3). Those with PD will be randomly assigned to either a TC group or a control group. The TC group will participate in a biomechanical-based TC training program that is formed based on the movement analysis of TC and will be practiced two to three times a week for 12 weeks. The control group will be asked to engage or maintain their regular physical activity (PA) for a period of 12 weeks. The primary and secondary outcomes will be assessed at baseline, 6-week, and 12-week after commencing the study protocol. The primary outcome measures will include gait speed, cadence, step length during level surface walking (simple task) and fixed-obstacle crossing (challenging task); the dynamic postural stability will be indicated by the center of mass and center of pressure (COM-COP) separation distance and clearance distance measured during fixed-obstacle crossing. The secondary measures will be the Unified Parkinson’s disease Rating scale (UPDRS-III), single leg-stance test with eyes open and closed, and three cognitive scores (Stroop Test, Trail Making Test- Part B, and the Wisconsin Card Sorting Test). DiscussionThis protocol could lead to the development of an original and innovative TC training program for improvement of gait and postural stability among individuals with PD, which could help to improve or preserve the participants’ self-confidence, active participation in social activities, and therefore be beneficial to their overall quality of life.Trial registration: ClinicalTrials.gov (registry), NCT04644367 (registration number), November 25, 2020 (date of registration).