Evaluation of the bilateral symmetry assumption in manual wheelchair propulsion: a systematic review of literature in daily-life and sports contexts.

ABSTRACT: This systematic review aimed to 1) verify bilateral symmetry assumption in manual wheelchair (MWC) propulsion in daily-life and sports, and its relationship with injury risk and sports performance; 2) evaluate methods for assessing bilateral symmetry. Scopus, Web-Of-Science, PubMed, and EBSCO databases were searched for articles published before January 2024 investigating bilateral symmetry in MWC users and/or healthy participants during MWC propulsion. Two independent reviewers screened, extracted data, and assessed methodological quality of retrieved papers. Twenty-five studies were included. In daily ground-level propulsion, minimal asymmetries were observed in kinematic, kinetic, and temporal parameters when averaging ≥3 push cycles. In the sports context, diverse findings emerged, ranging from up to 27% side-to-side differences in propulsion kinetics and kinematics during sprinting, to descriptions of both symmetrical and asymmetrical upper extremity motions. Limited evidence exists regarding the role of asymmetry in MWC propulsion as a risk factor for injury and pain, as well as the association between sprinting performance and symmetry. In conclusion, bilateral symmetry assumption in MWC propulsion is valid only under specific conditions (i.e., slow/moderate speed, averaging ≥3 push cycles, smooth level ground). The wheeling environment and inter-individual variability impact symmetry research outcome and require consideration in future studies.

Expert Consensus on Classification and Performance in Paralympic Powerlifting: A Delphi Study.

BACKGROUND: In Paralympic sports, classification ensures fair competition by grouping athletes based on their impairments. The International Paralympic Committee has provided scientific principles to guide evidence-based classification procedures. In Paralympic Powerlifting, athletes compete in one class, divided by sex and bodyweight categories, overlooking impairment impact on performance. OBJECTIVE: This study aimed to establish a consensus among international Paralympic powerlifting experts regarding classification and performance issues to guide future research. METHODS: A two-round Delphi study was conducted involving 26 experts. The study sought to identify the adequacy of the current classification and competition systems, explore the impact of various impairments, and lay the initial groundwork for a performance determinants model. RESULTS: Experts agreed that existing classification and competition systems in Paralympic powerlifting do not align with Paralympic standards. Impairments from neurological conditions and those causing anthropometric changes were suggested to have opposing performance impacts. Initial directions for a performance determinants model were outlined, focusing on arm and bar kinematics, anthropometry, and body composition. CONCLUSIONS: This study underscores the need for comprehensive research in Paralympic powerlifting, revealing critical discrepancies between current classification system and Paralympic standards. Insights into the multifaceted relationship between impairments and performance are provided to shape the future of Paralympic powerlifting research.

Variability analysis of muscle activation symmetry to identify indicators of individual motor strategy: a case series on elite Paralympic powerlifters.

Introduction: In Paralympic powerlifting competitions, movement execution symmetry is a technical requirement influenced by individual athlete characteristics and motor strategies. Identifying the elements associated with individual motor strategies can offer valuable insight for improving sport performance. Therefore, this case series study aimed to explore muscle activation symmetry and its intra- and inter-individual variability to determine the muscles mostly related to individual motor strategies in elite Paralympic powerlifters. Methods: Bilateral electromyographic activation of the anterior deltoid (AD), pectoralis major (PM), latissimus dorsi (LD), triceps (TRI) and external oblique (EO) muscles were analysed in five elite Paralympic powerlifters while performing four sets of one-repetition maximum of Paralympic bench press. Muscle activation symmetry indexes (SI) were obtained and transformed to consider individual-independent evaluation. The coefficient of variation (CV), variance ratio (VR), and mean deviation (MD) were computed to assess inter- and intra-individual variability in electromyographic waveforms and SI. Results: Both transformed and non-transformed SI indicated overall symmetric activation in DA, PM, TRI, and LD. Transformed SI revealed asymmetrical muscle activation of EO when grouping data (mean bilateral difference: 10%). Athletes exhibited low intra-individual SI variability in all analysed muscles (CV < 10%) and low inter-individual variability in DA, PM, LD, and TRI (CV < 10%; VR: 4%-11%; MD: 29%-43%). In contrast, higher inter-individual variability was observed in EO (CV: 23%; VR: 23%; MD: 72%-81%). Conclusion: The highest variability and asymmetry in abdominal muscle activation among athletes emphasize the importance of personalized training approaches for targeting these muscles due to their role in individualizing motor strategies.

"Posture first": Interaction between posture and locomotion in people with low back pain during unexpectedly cued modification of gait initiation motor command.

The ability to adapt anticipatory postural adjustments (APAs) in response to perturbations during single-joint movements is altered in people with chronic low back pain (LBP), but a comprehensive analysis during functional motor tasks is still missing. This study aimed to compare APAs and stepping characteristics during gait initiation between people with LBP and healthy controls, both in normal (without cue occurrence) condition and when an unexpected visual cue required to switch the stepping limb. Fourteen individuals with LPB and 10 healthy controls performed gait initiation in normal and switch conditions. The postural responses were evaluated through the analysis of center of pressure, propulsive ground reaction forces, trunk and whole-body kinematics, and activation onsets of leg and back muscles. During normal gait initiation, participants with LBP exhibited similar APAs and stepping characteristics to healthy controls. In the switch condition, individuals with LBP were characterized by greater mediolateral postural stability but decreased forward body motion and propulsion before stepping. The thorax motion was associated with forward propulsion parameters in both task conditions in people with LBP but not healthy controls. No between-group differences were found in muscle activation onsets. The results suggest that postural stability is prioritized over forward locomotion in individuals with LBP. Furthermore, the condition-invariant coupling between thorax and whole-body forward propulsion in LBP suggests an adaptation in the functional use of the thorax within the postural strategy, even in poor balance conditions.

Validation of an Automatic Inertial Sensor-Based Methodology for Detailed Barbell Velocity Monitoring during Maximal Paralympic Bench Press.

Current technologies based on inertial measurement units (IMUs) are considered valid and reliable tools for monitoring barbell velocity in strength training. However, the extracted outcomes are often limited to a few velocity metrics, such as mean or maximal velocity. This study aimed at validating a single IMU-based methodology to automatically obtain the barbell velocity full profile as well as key performance metrics during maximal Paralympic bench press. Seven Paralympic powerlifters (age: 30.5 ± 4.3 years, sitting height: 71.6 ± 6.8 cm, body mass: 72.5 ± 16.4 kg, one-repetition maximum: 148.4 ± 38.6 kg) performed four attempts of maximal Paralympic bench press. The barbell velocity profile and relevant metrics were automatically obtained from IMU linear acceleration through a custom-made algorithm and validated against a video-based reference system. The mean difference between devices was 0.00 ± 0.04 m·s−1 with low limits of agreement (<0.09 m·s−1) and moderate-to-good reliability (ICC: 0.55−0.90). Linear regression analysis showed large-to-very large associations between paired measurements (r: 0.57−0.91, p < 0.003; SEE: 0.02−0.06 m·s−1). The analysis of velocity curves showed a high spatial similarity and small differences between devices. The proposed methodology provided a good level of agreement, making it suitable for different applications in barbell velocity monitoring during maximal Paralympic bench press.

Performance assessment in archery: a systematic review.

Archery is a sport accessible to a wide range of people, no matter their age, gender or ability, and can be practiced both by able-bodied and impaired athletes on a level playing field. The recent increase in the number of studies concerning the biomechanical evaluation of the archery discipline revealed the need to advance an evidence-based approach for a standardised and objective assessment of the athletic gesture. A systematic literature search of relevant databases in July 2021 yielded 41 studies spanning 35 years (1986-2021). The research strings focused on the parameters, employed measurement systems and on the outcomes. The investigation of the influence of a wide range of physiological and kinematic parameters on the archer performance revealed that expert athletes tend to maximise postural stability and develop personal strategies of muscular activation and time management. These findings evidenced the importance of the repeatability of the technical gesture, opening additional scenarios for further investigations.

Train at home, but not alone: a randomised controlled multicentre trial assessing the effects of live-streamed tele-exercise during COVID-19-related lockdowns.

OBJECTIVE: Public life restrictions associated with the COVID-19 pandemic caused reductions in physical activity (PA) and decreases in mental and somatic health. Considering the interplay between these factors, we investigated the effects of digital home exercise (DHE) during government-enforced lockdowns. METHODS: A multicentre randomised controlled trial was performed allocating healthy individuals from nine countries (N=763; 523 female) to a DHE or an inactive control group. During the 4-week main intervention, DHE members engaged in live-streamed multicomponent home exercise. Subsequently, both groups had access to prerecorded workouts for an additional 4 weeks. Outcomes, assessed weekly, included PA level (Nordic Physical Activity Questionnaire-Short), anxiety (Generalized Anxiety Disorder Scale-7), mental well-being (WHO-5 Questionnaire), sleep quality (Medical Outcome Study Sleep Scale), pain/disability (Chronic Pain Grade Scale) and exercise motivation (Self-Concordance Scale). Mixed models were used for analysis. RESULTS: Live-streamed DHE consistently increased moderate PA (eg, week 1: 1.65 times more minutes per week, 95% CI 1.40 to 1.94) and vigorous PA (eg, week 1: 1.31 times more minutes per week, 95% CI 1.08 to 1.61), although the effects decreased over time. In addition, exercise motivation, sleep quality and anxiety were slightly improved for DHE in the 4-week live streaming period. The same applied to mental well-being (mean difference at week 4: +0.99, 95% CI 0.13 to 1.86), but an inverted trend was observed after live streaming was substituted by prerecorded exercise. CONCLUSIONS: Live-streamed DHE represents an efficacious method to enhance PA and selected markers of health during pandemic-related public life restrictions. However, research on implementation is warranted to reduce dropout rates. TRIAL REGISTRATION NUMBER: DRKS00021273.

Wearable Sensors in Sports for Persons with Disability: A Systematic Review.

The interest and competitiveness in sports for persons with disabilities has increased significantly in the recent years, creating a demand for technological tools supporting practice. Wearable sensors offer non-invasive, portable and overall convenient ways to monitor sports practice. This systematic review aims at providing current evidence on the application of wearable sensors in sports for persons with disability. A search for articles published in English before May 2020 was performed on Scopus, Web-Of-Science, PubMed and EBSCO databases, searching titles, abstracts and keywords with a search string involving terms regarding wearable sensors, sports and disability. After full paper screening, 39 studies were included. Inertial and EMG sensors were the most commonly adopted wearable technologies, while wheelchair sports were the most investigated. Four main target applications of wearable sensors relevant to sports for people with disability were identified and discussed: athlete classification, injury prevention, performance characterization for training optimization and equipment customization. The collected evidence provides an overview on the application of wearable sensors in sports for persons with disability, providing useful indication for researchers, coaches and trainers. Several gaps in the different target applications are highlighted altogether with recommendation on future directions.

Biomechanical characteristics of handstand walking initiation.

BACKGROUND: The initiation in human locomotion is defined as the transition between upright stance and steady-state gait. While past literature abundantly investigated the initiation in bipedal gait, the initiation of handstand walking remains unexplored. RESEARCH QUESTION: The current study aims to characterise the centre of pressure (CoP) and centre of mass (CoM) trajectory of handstand walking initiation as well as the spatiotemporal and kinematic parameters and balance strategy of this task. Also, the study examined the CoP trajectory similarity within- and between-participants using a coefficient of multiple correlation analysis. METHODS: Nineteen gymnasts took part in this study. Handstand walking initiation trials were recorded using force plates and a stereophotogrammetric system. CoM and CoP trajectories were analysed during the Baseline, Preparation and Execution phases of the motor task. RESULTS: We found that to successfully perform the handstand walking initiation, a shift of the CoM forward and towards the stance hand is required as a result of a lateral and posterior CoP shift. All participants performed a similar CoP pattern in the mediolateral direction, whereas two anteroposterior CoP displacement strategies were identified across participants based on different timing execution of posterior CoP shift. While CoP and CoM kinematic differences were identified during the Preparation Phase due to the adopted strategy, no significant difference was found in the Execution Phase for the spatiotemporal and kinematic characteristics. SIGNIFICANCE: A better understanding of the required CoP/CoM patterns and balance control provides the basis for further neuromechanics research on the topic and could contribute to individualise training protocols to improve the learning of the task.

Non-specific chronic low back pain elicits kinematic and neuromuscular changes in walking and gait termination.

BACKGROUND: Chronic low back pain (CLBP) is associated with an increased trunk stiffness and muscle coactivation during walking. However, it is still unclear whether CLBP individuals are unable to control neuromechanically their upper body motion during a sudden termination of gait (GT), which involves a challenging balance transition from walking to standing. RESEARCH QUESTION: Does CLBP elicit neuromuscular and kinematic changes which are specific to walking and GT?. METHODS: Eleven individuals with non-specific CLBP and 11 healthy controls performed walking and sudden GT in response to an external visual cue. 3D kinematic characteristics of thorax, lumbar and pelvis were obtained, with measures of range of motion (ROM) and intra-subject variability of segmental movement being calculated. Electromyographic activity of lumbar and abdominal muscles was recorded to calculate bilateral as well as dorsoventral muscle coactivation. RESULTS: CLBP group reported greater transverse ROM of the lumbar segment during walking and GT compared to healthy controls. Thorax sagittal ROM was higher in CLBP than healthy participants during GT. Greater overall movement variability in the transverse plane was observed in the CLBP group while walking, whereas GT produced greater variability of lumbar frontal motion. CLBP participants showed higher bilateral lumbar coactivation compared to healthy participants after the stopping stimulus delivery during GT. SIGNIFICANCE: These results suggest that CLBP can elicit a wider and more variable movement of the upper body during walking and GT, especially in the transverse plane and at lumbar level. Alterations in upper body motor control appeared to depend on task, plane of motion and segmental level. Therefore, these findings should be considered by practitioners when screening before planning specific training interventions for recovery of motor control patterns in CLBP population.

Neuromechanical response of the upper body to unexpected perturbations during gait initiation in young and older adults.

BACKGROUND: Control of upper body motion deteriorates with ageing leading to impaired ability to preserve balance during gait, but little is known on the contribution of the upper body to preserve balance in response to unexpected perturbations during locomotor transitions, such as gait initiation. AIM: To investigate differences between young and older adults in the ability to modify the trunk kinematics and muscle activity following unexpected waist lateral perturbations during gait initiation. METHODS: Ten young (25 ± 2 years) and ten older adults (73 ± 5 years) initiated locomotion from stance while a lateral pull was randomly applied to the pelvis. Two force plates were used to define the feet centre-of-pressure displacement. Angular displacement of the trunk in the frontal plane was obtained through motion analysis. Surface electromyography of cervical and thoracic erector spinae muscles was recorded bilaterally. RESULTS: A lower trunk lateral bending towards the stance leg side in the preparatory phase of gait initiation was observed in older participants following perturbation. Right thoracic muscle activity was increased in response to the perturbation during the initial phase of gait initiation in young (+ 68%) but not in older participants (+ 7%). CONCLUSIONS: The age-related reduction in trunk movement could indicate a more rigid behaviour of the upper body employed by older compared to young individuals in response to unexpected perturbations preceding the initiation of stepping. Older adults' delayed activation of thoracic muscles could suggest impaired reactive mechanisms that may potentially lead to a fall in the early stages of the gait initiation.

Age differences in anticipatory and executory mechanisms of gait initiation following unexpected balance perturbations.

PURPOSE: An age-related decline in anticipatory postural mechanisms has been reported during gait initiation; however, it is unclear whether such decline may jeopardize whole-body stability following unexpected balance perturbations. This study aimed to compare young and older individuals' ability to generate postural responses and preserve stability in response to external waist perturbations delivered within gait initiation. METHODS: Ten young and ten older participants performed 10 gait initiation trials followed by 48 unperturbed and 12 perturbed trials in a random order. A stereophotogrammetric system and three force platforms were used to quantify mechanical parameters from the preparatory phase (e.g., timing and amplitude of postural adjustments) and from the stepping phase (e.g., step characteristics and dynamic stability). Activation patterns of lower leg muscles were determined by surface electromyography. RESULTS: Older participants responded to perturbation with lower increase in both magnitude (p < 0.001; η2p = 0.62) and duration (p = 0.001; η2p = 0.39) of preparatory parameters and soleus muscle activity (p < 0.001; η2p = 0.55), causing shorter (p < 0.001; η2p = 0.59) and lower (p < 0.001; η2p = 0.43) stepping, compared to young participants. Interestingly, young participants showed greater correlations between preparatory phase parameters and dynamic stability of the first step than older participants (average r of - 0.40 and - 0.06, respectively). CONCLUSION: The results suggest that young participants took more time than older to adjust the anticipatory biomechanical response to perturbation attempting to preserve balance during stepping. In contrast, older adults were unable to modify their anticipatory adjustments in response to perturbation and mainly relied on compensatory mechanisms attempting to preserve stability via a more cautious stepping strategy.

Sarcopenia, Diet, Physical Activity and Obesity in European Middle-Aged and Older Adults: The LifeAge Study.

The revised European consensus defined sarcopenia as a progressive and generalized skeletal muscle disorder that is associated with an increased likelihood of adverse outcomes including falls, fractures, physical disability and mortality. The aim of this study was to determine the prevalence of sarcopenia and analyse the influence of diet, physical activity (PA) and obesity index as risk factors of each criteria of sarcopenia. A total of 629 European middle-aged and older adults were enrolled in this cross-sectional study. Anthropometrics were assessed. Self-reported PA and adherence to the Mediterranean diet were evaluated with the Global Physical Activity Questionnaire (GPAQ) and Prevention with Mediterranean Diet questionnaire (PREDIMED), respectively. The functional assessment included handgrip strength, lower body muscle strength, gait speed and agility/dynamic balance. Of the participants, 4.84% to 7.33% showed probable sarcopenia. Sarcopenia was confirmed in 1.16% to 2.93% of participants. Severe sarcopenia was shown by 0.86% to 1.49% of participants. Male; age group ≤65 years; lower body mass index (BMI); high levels of vigorous PA; and the consumption of more than one portion per day of red meat, hamburgers, sausages or cold cuts and/or preferential consumption of rabbit, chicken or turkey instead of beef, pork, hamburgers or sausages (OR = 0.126-0.454; all p < 0.013) resulted as protective factors, and more time of sedentary time (OR = 1.608-2.368; p = 0.032-0.041) resulted as a risk factor for some criteria of sarcopenia. In conclusion, age, diet, PA, and obesity can affect the risk of having low muscle strength, low muscle mass or low functional performance, factors connected with sarcopenia.

Innovative rehabilitative bracing with applied resistance improves walking pattern recovery in the early stages of rehabilitation after ACL reconstruction: a preliminary investigation.

BACKGROUND: The use of knee braces early after anterior cruciate ligament (ACL) reconstruction is a controversial issue. The study preliminarily compares the effect of a traditional brace blocked in knee extension and a new functional brace equipped with a spring resistance on walking and strength performance early after ACL reconstruction performed in the acute/subacute stage. METHODS: 14 ACL-reconstructed patients wore either a traditional (Control group: CG, 7 subjects) or a new functional brace (Experimental group: EG 7 subjects) until the 30th post-operative day. All patients were tested before surgery (T0), 15, 30, and 60 days after surgery (T1, T2, and T3, respectively). Knee angular displacement and ground reaction forces (GRF) during the stance phase of the gait cycle were analyzed at each session and, at T3, maximal voluntary isometric contraction (MVIC) for knee flexor/extensor muscles was performed. Limb symmetry indexes (LSI) of GRF and MVIC parameters were calculated. RESULTS: At T3, EG showed greater peak knee flexion angle of injured limb compared to CG (41 ± 2° vs 32 ± 1°, p < 0.001). During weight acceptance, a significant increase of anteroposterior GRF peak and vertical impulse from T1 to T3 was observed in the injured limb in EG (p < 0.05) but not in CG (p > 0.05). EG showed a greater side-to-side LSI of weight acceptance peak of anteroposterior GRF at T2 (113 ± 23% vs 69 ± 11%, p < 0.05) and T3 (112 ± 23% vs 84 ± 10%, p < 0.05). CONCLUSIONS: The preliminary findings from this study indicate that the new functional brace did help in improving gait biomechanical pattern in the first two months after ACL reconstruction compared to a traditional brace locked in knee extension.

Stepping forward, stepping backward: a movement-related cortical potential study unveils distinctive brain activities.

Human locomotion is the product of complex dynamic systems, which rely on physical capacities as well as cognitive functions. In our daily life, we mostly experience forward walking, but also backward stepping can occur, as in protective stepping. In this work, we investigated the electroencephalographic (EEG) correlates of cognitive processing underpinning step initiation by means of movement-related cortical potentials (MRCPs) analysis and force-plates recordings. Healthy young volunteers (N = 11) performed self-paced forward- and backward-oriented steps on two force platforms, which were synchronized to simultaneous EEG recordings. MRCPs and their source localization analyses were computed. Results demonstrate the involvement of cognitive processing during step preparation and execution, as showed by the prefrontal activity, which was enhanced in backward stepping. Further, the parietal activity was larger in forward than backward stepping, while motor-related regions were involved in both step directions. Thus, the neural timing and sources of forward and backward stepping suggest a functional distinction of these two actions, which undergo different cortical organizations. Backward stepping requires enhanced cognitive control and can be regarded as an avoidance behavior, while forward stepping would be assimilated to an oriented-to-action behavior mainly localized over parietal areas. In conclusion, preparing body locomotion involves high cognitive processing, with step direction showing different cortical organization and functional specialization.

Age-related changes in upper body contribution to braking forward locomotion in women.

INTRODUCTION: Gait termination is a transitory task that requires the lower body to produce braking forces and inhibit forward propulsion. However, it is still unknown whether the upper body plays an active role in braking of gait and whether this mechanism is impaired with ageing. RESEARCH QUESTION: Do older women exhibit an impaired control of upper body segments during gait termination with respect to young women? METHODS: Ten young and 10 older women performed three gait termination trials at comfortable speed while fixing the gaze on a visual target. A 3D motion analysis system was used to measure head, trunk and pelvis angular displacement and velocity, and estimate neck, waist and hip moments through Plug-in Gait modeling. Cross-correlation analysis of kinematic waveforms between paired adjacent segments (head-trunk and trunk-pelvis) was performed to investigate upper body coordination. Surface EMG activity of erector spinae (L3), sternocleidomastoid and neck extensor muscles was recorded. Statistics was carried out by MANOVA. RESULTS: Older participants exhibited delayed peak extensor torques of neck, waist and hip compared to young participants, along with lower progression speed. Both groups showed a slight flexion of the trunk counteracted by a backward tilt of head and pelvis during braking. In addition, older women displayed a peculiar upper body coordination pattern, with the head coupling with trunk motion, as shown by cross-correlation. Older women displayed shorter lumbar erector spinae onset latency relative to last heel contact than young (16 ± 68 ms vs 92 ± 37 ms). SIGNIFICANCE: The upper body plays an active role in the braking of gait and this mechanism is impaired in older women. Moreover, the age-related coupling of head and trunk motion may produce an unbalancing effect on whole-body stability during the braking mechanism, thus leading to a higher risk of falls.

Upper body accelerations during planned gait termination in young and older women.

Transitory tasks, such as gait termination, involve interactions between neural and biomechanical factors that challenge postural stability and head stabilization patterns in older adults. The aim of the study was to compare upper body patterns of acceleration during planned gait termination at different speeds between young and older women. Ten young and 10 older women were asked to carry out three gait termination trials at slow, comfortable and fast speed. A stereophotogrammetric system and a 15-body segments model were used to calculate antero-posterior whole-body Center of Mass (AP CoM) speed and to reconstruct the centroids of head, trunk and pelvis segments. RMS of three-dimensional linear accelerations were calculated for each segment and the transmission of acceleration between two segments was expressed as a percentage difference. Older women reported lower AP CoM speed and acceleration RMS of the three upper body segments than young women across the three speed conditions. A lower pelvis-to-trunk attenuation of accelerations in the transverse plane was observed in older compared to young women, and mainly in the medio-lateral direction. As possible explanations, older women may not need to reduce acceleration as young women because of their lower progression speed and the subsequent acceleration at upper body levels. On the other hand, older women may prioritize a decrease in the whole body progression speed at expense of the involvement of upper body segments. This limits the attenuation of the accelerations, particularly in the transverse plane, implying an increased dynamic unbalance in performing this transitory task.