How do neuromuscular characteristics of the peroneal muscles differ in adults with and without chronic ankle instability? A systematic review with meta-analysis

BACKGROUND

Chronic ankle instability (CAI) has been associated with neuromuscular control dysfunction, particularly of the peroneal musculature.

RESEARCH QUESTION

How do neuromuscular characteristics of the peroneal muscles, including corticospinal excitability, strength, proprioception (force sense) and electromyographic measures differ in individuals with CAI compared to healthy control counterparts aged 18-45?

METHODS

A systematic review with meta-analysis was conducted by retrieving relevant articles from electronic databases including EBSCOhost (CINAHL Complete, AMED, SPORTDiscus), Ovid (MEDLINE, Embase), Web of Science, Scopus and Cochrane Library as well as Grey literature sources. The eligibility and methodological quality of the included case-control and cross-sectional studies were assessed by two reviewers. The random effects model and the standard mean difference with a 95 % confidence interval were utilised to calculate pooled estimates of the overall effect size.

RESULTS

Of the total 13,670 studies retrieved, 42 were included in the systematic review. Of these, 25 were eligible for the meta-analyses. Two of the meta-analyses, each consisting of two studies, showed less evertor force sense accuracy at 10 % (d=0.50, p = 0.03) and 20 % of maximum voluntary isometric contraction (d=1.14, p < 0.00001) in individuals with CAI than the control group. In addition, another meta-analysis of two studies showed that the CAI population had longer peroneus longus latency (d=1.69, p < 0.0001) than the control group during single-leg landing inversion perturbation test under unexpected conditions.

SIGNIFICANCE

Individuals with CAI showed specific sensorimotor impairments in evertor force sense accuracy and peroneus longus latency, which may indicate that neuromuscular dysfunction of the peroneal muscles is associated with the underlying mechanisms of the CAI pathogenesis. However, the meta-analyses are limited by the inclusion of only two studies with small sample sizes. Therefore, these findings should be cautiously interpreted, and further research is required to validate them.

Ability of a passive back support exoskeleton to mitigate fatigue related adaptations in a complex repetitive lifting task

As work related musculoskeletal disorders (WRMSDs) increase in prevalence, it is important to not only understand the mechanisms underpinning WRMSDs but also investigate ways to mitigate them in the workplace. Exoskeletons are an emerging technology which can reduce the physical demands required from the worker to perform lifting tasks. Previous research has primarily studied the effectiveness of back-support exoskeletons in constrained, flexion/extension tasks. The purpose of this study was to evaluate the effect of a passive back-support exoskeleton in a complex, multiplanar repetitive manual materials handling (MMH) task. Participants (n = 14) completed a multi-planar lifting, transferring, and lowering task for sixty minutes with and without wearing a passive back-support exoskeleton (HeroWear Apex 2). Full body kinematics as well as trunk and shoulder surface electromyography were collected for the entire trial. The back-support exoskeleton significantly decreased ratings of perceived exertion (p < 0.0001) Participants exhibited faster task completion times in the exoskeleton condition (p = 0.0095). Both movement coordination and coordination variability differed between conditions with increased shoulder-lumbar variability (p = 0.0466 - <.0001) and decreased thorax-pelvis variability (p = 0.0281) in the exoskeleton condition. Additionally, the back-support exoskeleton significantly reduced lumbar erector spinae muscle activity asymmetrically (p < 0.0001). While these findings generally support the idea that a passive back-support exoskeleton is effective in altering indicators of fatigue which can lead to injury, more research is needed to study different exoskeleton assistance levels and different types of exoskeletons before recommending their use across a diverse range of occupational settings.

EFFECT OF RESTRICTED HIP FLEXOR MUSCLE LENGTH ON HIP EXTENSOR MUSCLE ACTIVITY AND LOWER EXTREMITY BIOMECHANICS IN COLLEGE-AGED FEMALE SOCCER PLAYERS

BACKGROUND

Hip flexor tightness is theorized to alter antagonist muscle function through reciprocal inhibition and synergistic dominance mechanisms. Synergistic dominance may result in altered movement patterns and increased risk of lower extremity injury.

HYPOTHESIS/PURPOSE

To compare hip extensor muscle activation, internal hip and knee extension moments during double-leg squatting, and gluteus maximus strength in those with and without clinically restricted hip flexor muscle length.

DESIGN

Causal-comparative cross-sectional laboratory study.

METHOD

Using a modified Thomas Test, female soccer athletes were assigned to a restricted (>0 ° of sagittal plane hip motion above the horizontal; n=20, age=19.9 ± 1 years, ht=167.1 ± 6.4 cm, mass=64.7 ± 8.2kg) or normal (>15 ° of sagittal plane hip motion below horizontal; n=20, age=19.4 ± 1 years, ht=167.2 ± 5.5 cm, mass=61.2 ± 8.6 kg) hip flexor muscle length group. Surface electromyographic (sEMG) activity of the gluteus maximus and biceps femoris, and net internal hip and knee extension moments were measured between groups during a double-leg squat. Isometric gluteus maximus strength was assessed using handheld dynamometry.

RESULTS

Individuals with restricted hip flexor muscle length demonstrated less gluteus maximus activation (p=0.008) and a lower gluteus maximus : biceps femoris co-activation ratio (p=0.004). There were no significant differences (p>0.05) in hip or knee extension moments, isometric gluteus maximus strength, or biceps femoris activation between groups.

CONCLUSIONS

Female soccer athletes with hip flexor muscle tightness exhibit less gluteus maximus activation and lower gluteus maximus : biceps femoris co-activation while producing similar net hip and knee extension moments. Thus, individuals with hip flexor muscle tightness appear to utilize different neuromuscular strategies to control lower extremity motion.

LEVEL OF EVIDENCE

3.