Electromyographic analysis of balance exercises in single-leg stance using different instability modalities of the forefoot and rearfoot

Exploring biomechanical variations in ankle joint injuries among Latin dancers with different stance patterns: utilizing OpenSim musculoskeletal models

Background: Dancers represent the primary demographic affected by ankle joint injuries. In certain movements, some Latin dancers prefer landing on the Forefoot (FT), while others prefer landing on the Entire foot (ET). Different stance patterns can have varying impacts on dancers' risk of ankle joint injuries. The purpose of this study is to investigate the differences in lower limb biomechanics between Forefoot (FT) dancers and Entire foot (ET) dancers. Method: A group of 21 FT dancers (mean age 23.50 (S.D. 1.12) years) was compared to a group of 21 ET dancers (mean age 23.33 (S.D. 0.94) years), performing the kicking movements of the Jive in response to the corresponding music. We import data collected from Vicon and force plates into OpenSim to establish musculoskeletal models for computing kinematics, dynamics, muscle forces, and muscle co-activation. Result: In the sagittal plane: ankle angle (0%-100%, p < 0.001), In the coronal plane: ankle angle (0%-9.83%, p = 0.001) (44.34%-79.52%, p = 0.003), (88.56%-100%, p = 0.037), ankle velocity (3.73%-11.65%, p = 0.017) (94.72-100%, p = 0.031); SPM analysis revealed that FT dancers exhibited significantly smaller muscle force than ET dancers around the ankle joint during the stance phase. Furthermore, FT dancers displayed reduced co-activation compared to ET dancers around the ankle joint during the descending phase, while demonstrating higher co-activation around the knee joint than ET dancers. Conclusion: This study biomechanically demonstrates that in various stance patterns within Latin dance, a reduction in lower limb stance area leads to weakened muscle strength and reduced co-activation around the ankle joint, and results in increased ankle inversion angles and velocities, thereby heightening the risk of ankle sprains. Nevertheless, the increased co-activation around the knee joint in FT dancers may be a compensatory response for reducing the lower limb stance area in order to maintain stability.

Involvement of Myofascial Spiral Chains of the Lower Limb in Semi-unipodal Balance: A Pilot Study

Introduction Single-leg stance has been extensively studied for functional evaluation, therapeutic exercise, sports training, and fall prevention. However, the motor strategies of the supporting limb have been investigated only at the ankle level. It is not known, at the hip, how the muscular system reacts to medial and lateral imbalances. We hypothesize, based on a myofascial chain approach, that the balance is managed by the front and back spiral chains. The aim of this work was to perform a preliminary experimental analysis to verify the spiral chain hypothesis, testing a method to investigate the motor strategies underlying equilibrium. Methods Five healthy subjects (i.e. without neurological or orthopedic pathologies affecting the upright position) underwent perturbations of their monopodal balance while a surface electromyographic analysis of gluteus maximus, gluteus medius, adductor longus (ADD), tibialis anterior (TA), and peroneus longus (PL) was executed. The percentage of electrical activation with respect to maximal contraction was calculated for each muscle investigated. The coordination in activation between the hip and ankle muscles was analyzed by the Pearson correlation coefficient. Results Of the studied muscles, TA (43% of maximal contraction) and gluteus medius (28%) had the average highest reaction to lateral imbalance and the highest correlation coefficient (0.89, p-value<0.01); PL (35%) and ADD (16%) were the most relevant in counteracting the medial imbalance (correlation coefficient=0.83, p-value<0.01).  Conclusion The study was performed on a few subjects, and the muscles of the lower limb were only partially investigated. However, the consistency of the results with former experimental studies provided preliminary evidence of the adequacy of the method adopted. The correlation of hip and ankle muscle activations was in line with the spiral chain hypothesis.

Kinematics and muscle activity of the lower limb during single-leg stance on the two sides of the Togu Jumper

Purpose: Togu Jumper is a both sides utilized balance training device, which consists of an inflated rubber hemisphere attached to a rigid platform. It has been shown to be effective in improving postural control but there are no recommendations for the usage of the sides. Our aim was to examine leg muscle activity and kinematics in response to a single-leg stance on the two sides of the Togu Jumper and the floor. Methods: In 14 female subjects, linear acceleration of leg segments, segmental angular sway, and myoelectric activity of 8 leg muscles were recorded in the three stance conditions. Results: Except gluteus medius and gastrocnemius medialis, all muscles were more active when balancing on either Togu Jumper side compared to the floor (p < 0.001), but there was no difference between the two sides in any muscles. Linear acceleration was the greatest in the frontal plane on the flat Togu side in the case of the foot (p < 0.001). Pelvis acceleration was unaffected by the balance conditions. Segmental angular sway was the greatest in the frontal plane, on the bladder side in the foot segment (p < 0.001). No difference was found among the three conditions (all p > 0.05) in the case of the shank, thigh, and pelvis. Conclusion: The use of the two Togu Jumper sides produced different balance strategies in the foot segment and induced no difference in equilibrium procedures at the level of the pelvis.

Differences in lower limb muscle activation between global and selective instability devices in single-leg stance in healthy active subjects

Background

Balance and strength training are frequent strategies to address lower limb injuries, including ankle injuries, which are usually performed in single-leg stance on global instability devices, producing generalized muscular activation of the lower limb. In this context, new specific instability devices arise from the need to selectively work the ankle, specifically the peroneus longus. This study aimed to compare the EMG muscle activation of the peroneus longus, as well as other lower limbs muscles, in a single-leg stance on different balance training devices (BOSU, wobble board, power board, and Blackboard) in standing or squatting positions.

Methods

Twenty healthy recreationally trained subjects participated in the study. Subjects performed three repetitions of 15 s (one for familiarization and two for measurement) in standing and squatting positions on the floor, BOSU, wobble board, power board, and Blackboard. Surface electromyography (EMG) was used to record activity of the peroneus longus, soleus, gastrocnemius medialis, tibialis anterior, rectus femoris, and gluteus maximus.

Results

The main outcome was that no differences were found for the peroneus longus normalized EMG, neither between devices (p = 0.09) nor between conditions (p = 0.11), nor in the interaction between them (p = 0.16). For the normalized EMG of the other muscles, there were multiple differences between devices and conditions. Of the devices studied, the Blackboard was the one that implied a lower activation of the lower limb muscles and a lower degree of instability, activating the peroneus longus similarly to global instability devices. The BOSU and wobble board achieved high levels of EMG muscle activation for most muscles of the lower limbs. Therefore, they should be considered as potential devices for work in highly unstable conditions or when high activation levels are sought.

PManalyzer: A Software Facilitating the Study of Sensorimotor Control of Whole-Body Movements

Motion analysis is used to study the functionality or dysfunctionality of the neuromuscular system, as human movements are the direct outcome of neuromuscular control. However, motion analysis often relies on measures that quantify simplified aspects of a motion, such as specific joint angles, despite the well-known complexity of segment interactions. In contrast, analyzing whole-body movement patterns may offer a new understanding of movement coordination and movement performance. Clinical research and sports technique evaluations suggest that principal component analysis (PCA) provides novel and valuable insights into control aspects of the neuromuscular system and how they relate to coordinative patterns. However, the implementation of PCA computations are time consuming, and require mathematical knowledge and programming skills, drastically limiting its application in current research. Therefore, the aim of this study is to present the Matlab software tool "PManalyzer" to facilitate and encourage the application of state-of-the-art PCA concepts in human movement science. The generalized PCA concepts implemented in the PManalyzer allow users to apply a variety of marker set independent PCA-variables on any kinematic data and to visualize the results with customizable plots. In addition, the extracted movement patterns can be explored with video options that may help testing hypotheses related to the interplay of segments. Furthermore, the software can be easily modified and adapted to any specific application.

Effectiveness of backward walking training on balance performance: A systematic review and meta-analysis

BACKGROUND

Backward walking (BW) training is thought to impact balance performance through improving motor system proprioception and gait characteristic, but relevant evidence remains sparse and inconclusive.

OBJECTIVE

This study systematically reviewed and quantified the scientific evidence regarding the effectiveness of BW training on balance performance.

METHODS

Keyword and reference search on BW training interventions was conducted in six electronic databases (PubMed, Web of science, SPORTDiscus, CINAHL, Cochrane Library, and CNKI) for peer-reviewed articles published till November 2017. A standardized form was used to extract data from each selected article that met the pre-specified eligibility criteria. Meta-analysis was conducted to estimate the pooled effects of BW training on balance performance measures.

RESULTS

Eleven studies (nine randomized controlled trials and two pre-post studies) met the eligibility criteria and were included in the review. All studies reported some beneficial effects of BW training on balance performance. Compared to control, BW training was associated with a reduction in overall stability index score by 0.99 (95% CI = 0.37, 1.61; I² = 0.0%; fixed-effect model), medial-lateral stability index score by 0.95 (95% CI = 0.34, 1.57; I² = 0.0%; fixed-effect model), and anterior-posterior stability index score by 0.99 (95% CI = 0.37, 1.61; I² = 0.0%; fixed-effect model). Meanwhile, BW training was associated with an increase in open-eyes single leg standing duration by 0.91 s (95% CI = 0.29, 1.53; I² = 75.9%; random-effect model) in comparison to control.

CONCLUSIONS

BW training could serve as a potentially useful tool to improve balance performance among those with a high risk of fall. However, current evidence remains preliminary due to the small cohort of studies and possible learning effect in pre-post studies. Future work with larger scale and randomized experimental design is warranted to evaluate the effectiveness of BW training on balance performance across diverse population and disease subgroups, and elucidate the underlying biomechanical and neurological pathways.