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.

Long-term longitudinal study on swine VML model

BACKGROUND

Volumetric Muscle Loss (VML), resulting from severe trauma or surgical ablation, is a pathological condition preventing myofibers regeneration, since skeletal muscle owns the remarkable ability to restore tissue damage, but only when limited in size. The current surgical therapies employed in the treatment of this pathology, which particularly affects military personnel, do not yet provide satisfactory results. For this reason, more innovative approaches must be sought, specifically skeletal muscle tissue engineering seems to highlight promising results obtained from preclinical studies in VML mouse model. Despite the great results obtained in rodents, translation into human needs a comparable animal model in terms of size, in order to validate the efficacy of the tissue engineering approach reconstructing larger muscle mass (human-like). In this work we aim to demonstrate the validity of a porcine model, that has underwent a surgical ablation of a large muscle area, as a VML damage model.

RESULTS

For this purpose, morphological, ultrasound, histological and fluorescence analyses were carried out on the scar tissue formed following the surgical ablation of the peroneus tertius muscle of Sus scrofa domesticus commonly called mini-pig. In particular, the replenishment of the damaged area, the macrophage infiltration and the vascularization at different time-points were evaluated up to the harvesting of the scar upon six months.

CONCLUSION

Here we demonstrated that following VML damage, there is an extremely poor regenerative process in the swine muscle tissue, while the formation of fibrotic, scar tissue occurs. The analyses performed up to 180 days after the injury revealed the development of a stable, structured and cellularized tissue, provided with vessels and extracellular matrix acquiring the status of granulation tissue like in human.

Effects of SARS-CoV-2 on Pulmonary Function and Muscle Strength Testing in Military Subjects According to the Period of Infection: Cross-Sectional Study

BACKGROUND

Pulmonary function can be impaired as a long-term consequence of SARS-CoV-2 infection. The aim of this study was to evaluate the effect of SARS-CoV-2 infection on pulmonary function, exercise tolerance, and muscle strength in healthy middle-aged military outpatients according during the period of infection.

METHODS

A cross-sectional study was carried out from March 2020 to November 2022 at the Military Hospital "Celio" (Rome, Italy). If someone had a diagnosis of SARS-CoV-2 infection certified by molecular nasal swab and if they performed pulmonary function tests, diffusion of carbon monoxide (DL'co), a six Minute Walk Test (6MWT), a Handgrip (HG) Test, and a One Minute Sit to Stand Test (1'STST). The included subjects were divided into two groups, A and B, according to the period of infection: A) from March 2020 to August 2021 and B) from September 2021 to October 2022.

RESULTS

One hundred fifty-three subjects were included in the study: 79 in Group A and 74 in Group B. Although the values were within the normal range, Group A had smaller FVC, FEV_1, and DL'co compared to Group B. Group A also walked a shorter distance at the 6MWT and performed fewer repetitions in the 1'STS test compared to Group B. In both groups, the DL'co (%predicted) correlated with the 6MWT distance (R² = 0.107, p < 0.001), the number of repetitions of the 1'STST (R² = 0.086, p = 0.001), and the strength at the HG test (R² = 0.08, p < 0.001).

CONCLUSIONS

This study shows that the SARS-CoV-2 infection in healthy middle-aged military outpatients was more severe in the first waves than in the later ones and that, in healthy and physically fit individuals, even a marginal reduction in resting respiratory test values can have a major impact on exercise tolerance and muscles strength. Moreover, it shows that those infected more recently had symptoms related to the upper respiratory tract infection compared to those of the first waves.

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.

Strength Asymmetries Are Muscle-Specific and Metric-Dependent

We investigated if dominance affected upper limbs muscle function, and we calculated the level of agreement in asymmetry direction across various muscle-function metrics of two heterologous muscle groups. We recorded elbow flexors and extensors isometric strength of the dominant and non-dominant limb of 55 healthy adults. Participants performed a series of explosive contractions of maximal and submaximal amplitudes to record three metrics of muscle performance: maximal voluntary force (MVF), rate of force development (RFDpeak), and RFD-Scaling Factor (RFD-SF). At the population level, the MVF was the only muscle function that showed a difference between the dominant and non-dominant sides, being on average slightly (3–6%) higher on the non-dominant side. At the individual level, the direction agreement among heterologous muscles was poor for all metrics (Kappa values ≤ 0.15). When considering the homologous muscles, the direction agreement was moderate between MVF and RFDpeak (Kappa = 0.37) and low between MVF and RFD-SF (Kappa = 0.01). The asymmetries are muscle-specific and rarely favour the same side across different muscle-performance metrics. At the individual level, no one side is more performative than the other: each limb is favoured depending on muscle group and performance metric. The present findings can be used by practitioners that want to decrease the asymmetry levels as they should prescribe specific exercise training for each muscle.

Experimental study protocol of the project "MOtor function and VItamin D: Toolkit for motor performance and risk Assessment (MOVIDA)"

Musculoskeletal injuries, a public health priority also in the military context, are ascribed to several risk factors, including: increased reaction forces; low/reduced muscle strength, endurance, body mass, Vitamin D level, and bone density; inadequate lifestyles and environment. The MOVIDA Project-funded by the Italian Ministry of Defence-aims at developing a transportable toolkit (assessment instrumentation, assessment protocols and reference/risk thresholds) which integrates motor function assessment with biological, environmental and behavioural factors to help characterizing the risk of stress fracture, stress injury or muscle fatigue due to mechanical overload. The MOVIDA study has been designed following the STROBE guidelines for observational cross-sectional studies addressing healthy adults, both militaries and civilians, with varying levels of physical fitness (sedentary people, recreational athletes, and competitive athletes). The protocol of the study has been designed and validated and is hereby reported. It allows to collect and analyse anamnestic, diagnostic and lifestyle-related data, environmental parameters, and functional parameters measured through portable and wearable instrumentation during adapted 6 minutes walking test. The t-test, one and two-way ANOVA with post-hoc corrections, and ANCOVA tests will be used to investigate relevant differences among the groups with respect to biomechanical parameters; non-parametric statistics will be rather used for non-normal continuous variables and for quantitative discrete variables. Generalized linear models will be used to account for risk and confounding factors.

Overuse-Related Injuries of the Musculoskeletal System: Systematic Review and Quantitative Synthesis of Injuries, Locations, Risk Factors and Assessment Techniques

Overuse-related musculoskeletal injuries mostly affect athletes, especially if involved in preseason conditioning, and military populations; they may also occur, however, when pathological or biological conditions render the musculoskeletal system inadequate to cope with a mechanical load, even if moderate. Within the MOVIDA (Motor function and Vitamin D: toolkit for risk Assessment and prediction) Project, funded by the Italian Ministry of Defence, a systematic review of the literature was conducted to support the development of a transportable toolkit (instrumentation, protocols and reference/risk thresholds) to help characterize the risk of overuse-related musculoskeletal injury. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach was used to analyze Review papers indexed in PubMed and published in the period 2010 to 2020. The search focused on stress (overuse) fracture or injuries, and muscle fatigue in the lower limbs in association with functional (biomechanical) or biological biomarkers. A total of 225 Review papers were retrieved: 115 were found eligible for full text analysis and led to another 141 research papers derived from a second-level search. A total of 183 papers were finally chosen for analysis: 74 were classified as introductory to the topics, 109 were analyzed in depth. Qualitative and, wherever possible, quantitative syntheses were carried out with respect to the literature review process and quality, injury epidemiology (type and location of injuries, and investigated populations), risk factors, assessment techniques and assessment protocols.

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.

Hormetic Effects of Bioactive Compounds from Foods, Beverages, and Food Dressing: The Potential Role in Spinal Cord Injury

Spinal cord injury (SCI) is a damage or trauma to the spinal cord resulting in a total or partial loss of motor and sensory function. SCI is characterized by a disequilibrium between the production of reactive oxygen species and the levels of antioxidant defences, causing oxidative stress and neuroinflammation. This review is aimed at highlighting the hormetic effects of some compounds from foods, beverages, and food dressing that are able to reduce oxidative stress in patients with SCI. Although curcumin, ginseng, and green tea have been proposed for SCI management, low levels of antioxidant vitamins have been reported in individuals with SCI. Mediterranean diet includes food rich in vitamins and antioxidants. Moreover, food dressing, including spices, herbs, and extra virgin olive oil (EVOO), contains multiple components with hormetic effects. The latter involves the activation of the nuclear factor erythroid-derived 2, consequently increasing the antioxidant enzymes and decreasing inflammation. Furthermore, EVOO improves the bioavailability of carotenoids and could be a delivery system for bioactive compounds. In conclusion, Mediterranean dressing in addition to plant foods can have an important effect on redox balance in individuals with SCI.

Dietary Intakes and Food Habits of Wheelchair Basketball Athletes compared to Gym Attendees and Individuals who do not Practice Sport Activity

BACKGROUND

Mediterranean diet (Med-D) has been previously suggested for athletes, but Paralympics usually have a low intake of plant foods. Orthorexia nervosa (ON) can drive dietary intake of both athletes and gym attendees.

OBJECTIVE

We aimed to compare dietary intakes and food habits of elite wheelchair basketball athletes (WBA) and able-bodied individuals who practice or not sport activity and with different fat mass percentage (FM%).

METHODS

We recruited 15 WBA from the Italian National team and 3 control groups (15 each group): healthy individuals who do not practice any sport activity (NSA) and gym attendees with low (GAL, FM%<17) and high (GAH, FM%>18) FM%. Food consumption was monitored by 3-d diary, while Med-D scores and ON score were evaluated through standardized questionnaires. In WBA we also assessed Neurogenic Bowel Dysfunction (NBD), GastroEsophageal Reflux Disease (GERD), allergy questionnaire for athletes (AQUA) and Starvation Symptoms Inventory (SSI).

RESULTS

In WBA, ON correlated with GERD and SSI. WBA and GAH with eating behavior of ON had higher adherence to Med-D, whereas NSA had less adherence to Med-D. Sub-score including fruits, vegetables and legumes, was higher in the GAL and GAH groups compared to the WBA and NSA groups. Med-D was inversely related to animal protein intake (PRO-AN) in NSA and GAL. FM% was inversely related to PRO-AN in WBA and GAH, and to ON only in GAH. In WBA PRO-AN and vegetable protein intake correlated with both carbohydrate and energy intakes.

CONCLUSIONS

In WBA, commitment to wellness (ON and Med-D adherence) could be a response to gastrointestinal and starvation symptoms. WBA should be involved in setting their own individualized dietary strategies.

Post-Exercise Ketosis, Salivary Uric Acid and Interleukin-6 after a Simulated Wheelchair Basketball Match

BACKGROUND

Interleukin (IL)-6, total antioxidant capacity (TAC) and uric acid (UA) increase after exercise in able-bodied individuals. Wheelchair Basketball Athletes (WBA), having low muscle mass, could be at risk of post-exercise ketosis. <p >Objective: This study aimed to evaluate the post-exercise ketosis, IL-6 and antioxidant response, in WBA of the Italian National team, after a simulated match.

METHODS

Dietary intakes, Starvation Symptoms Inventory (SSI), percentage of fat mass (FM%) and basal Respiratory Exchange Ratio (RER) and Basal Energy Expenditure (BEE), were evaluated. Salivary TAC, UA and IL-6 were measured: before (PreM), at the end (EM) and 20 minutes after (PostM) the match. Capillary glucose and β-hydroxybutyrate (βHB) were monitored. Percentage of Heart Rate Reserve (%HRR) was measured to evaluate exercise intensity.

RESULTS

WBA had low carbohydrates (43.5% of daily energy intake (En)) and high fat (36.3% En) intakes. The increase in UA at PostM correlated with En (0.810, p<0.01) and was inversely related to βHB at EM (-0.719, p<0.05). Furthermore, at PostM growing IL-6 levels correlated with BEE (0.778, p<0.05) and inversely related to FM% (-0.762, p<0.5) were found, which in turn was correlated to SSI (0.781, p<0.05). Also βHB PostM correlated with SSI (0.761, p<0.05) but was inversely related to RER (-0.745, p<0.05) and En (-0.826, p<0.01).

CONCLUSIONS

Our study suggests that some WBA should improve their dietary habit in order to prevent post-exercise ketosis and ameliorate the endogenous antioxidant response after exercise.

Diet in neurogenic bowel management: A viewpoint on spinal cord injury

The aim of this review is to offer dietary advice for individuals with spinal cord injury (SCI) and neurogenic bowel dysfunction. With this in mind, we consider health conditions that are dependent on the level of lesion including skeletal muscle atrophy, autonomic dysreflexia and neurogenic bladder. In addition, SCI is often associated with a sedentary lifestyle, which increases risk for osteoporosis and diseases associated with chronic low-grade inflammation, including cardiovascular and chronic kidney diseases. The Mediterranean diet, along with exercise and dietary supplements, has been suggested as an anti-inflammatory intervention in individuals with SCI. However, individuals with chronic SCI have a daily intake of whole fruit, vegetables and whole grains lower than the recommended dietary allowance for the general population. Some studies have reported an increase in neurogenic bowel dysfunction symptoms after high fiber intake; therefore, this finding could explain the low consumption of plant foods. Low consumption of fibre induces dysbiosis, which is associated with both endotoxemia and inflammation. Dysbiosis can be reduced by exercise and diet in individuals with SCI. Therefore, to summarize our viewpoint, we developed a Mediterranean diet-based diet and exercise pyramid to integrate nutritional recommendations and exercise guidelines. Nutritional guidelines come from previously suggested recommendations for military veterans with disabilities and individuals with SCI, chronic kidney diseases, chronic pain and irritable bowel syndrome. We also considered the recent exercise guidelines and position stands for adults with SCI to improve muscle strength, flexibility and cardiorespiratory fitness and to obtain cardiometabolic benefits. Finally, dietary advice for Paralympic athletes is suggested.

Nutraceutical-based Integrative Medicine: Adopting a Mediterranean Diet Pyramid for Attaining Healthy Ageing in Veterans with Disabilities

Veterans with disability represent a big burden worldwide and often require long-term rehabilitation. Unhealthy dietary and lifestyle habits, including smoke and alcohol abuse, are common in veterans. In the context of integrative medicine approaches, the "complementary and alternative medicine" has been suggested for the management of chronic diseases. However, the potential risk of interaction between herbal products, dietary supplements and drugs must be considered in veterans. The Mediterranean diet has been suggested as a natural, non-pharmacological nutraceutical for healthy ageing. Although there is a broad consensus on the positive effect of plant foods consumption, the presence of glucosinolates, flavonoids and furanocoumarins in some plant foods and beverages must be taken into consideration owing to their potential interfering with drugs metabolism and bioavailability. Albeit seasonality could ensure the maintenance of the single dose of phytochemical below that at which adverse effects in some individuals genetically predisposed or unpleasant drug interactions in diseased subjects can occur, a personalized nutrition is recommended in veterans who are under treatment for comorbidities. Furthermore, sports practice can lead veterans with motor disabilities and mental impairments to excel in some disciplines, giving rise to the phenomenon of the Paralympics and the development of "recreational therapy". Moreover, outdoor lifestyle, through vitamin D synthesis, and conviviality, improving socialization, could account for the Mediterranean lifestyle health benefits. In this work, we propose for veterans a Mediterranean Pyramid, which could be the basis for integrative medicine for veterans with disabilities, patient-centered approaches and interprofessional (including physical medicine and rehabilitation clinicians, pharmacists and nutritionists) interventions.