Intra- and Inter-Limb Strength Asymmetry in Soccer: A Comparison of Professional and Under-18 Players

(1) Background: the present study examined the isokinetic peak torque exerted by both knee extensors and flexors, anterior–posterior imbalance and the magnitude and direction of inter-limb asymmetry in professional and academy soccer players. (2) Methods: one hundred soccer players (professional = 50, elite academy = 50) volunteered to take part in this investigation. An isokinetic dynamometer was used to measure the knee extensor (quadriceps) and flexors muscle (hamstrings) torques of the limbs as well as inter-limb asymmetries—using a standard percentage difference equation. (3) Results: professional players exhibited significantly greater (effect size [ES] = large) strength levels in the quadriceps and hamstrings under both testing conditions, significantly higher (small to moderate) intra-limb ratio values for 60°·s−1 but not for the 300°·s−1 test condition, significantly (small to moderate) lower inter-limb asymmetry values for all test conditions, with the exception of the hamstrings at 60°·s−1 and the direction of asymmetry was poor to slight, indicating that limb dominance was rarely the same between groups. (4) Conclusions: this study shows that isokinetic assessments, i.e., peak torque exerted by both knee extensors and flexors and intra-limb ratio, and the subsequent inter-limb asymmetry, i.e., magnitude and direction, can differentiate between professional and academy soccer players.

The Calculation, Thresholds and Reporting of Inter-Limb Strength Asymmetry: A Systematic Review

The prevalence of inter-limb strength differences is well documented in the literature however, there are inconsistencies related to measurement and reporting, and the normative values and effects associated with inter-limb asymmetry. Therefore, the aims of this systematic review were to: 1) assess the appropriateness of existing indices for the calculation of asymmetry, 2) interrogate the evidence basis for literature reported thresholds used to define asymmetry and 3) summarise normative levels of inter-limb strength asymmetry and their effects on injury and performance. To conduct this systematic review, scientific databases (PubMed, Scopus, SPORTDiscus and Web of Science) were searched and a total of 3,594 articles were retrieved and assessed for eligibility and article quality. The robustness of each identified asymmetry index was assessed, and the evidence-basis of the identified asymmetry thresholds was appraised retrospectively using the references provided. Fifty-three articles were included in this review. Only four of the twelve identified indices were unaffected by the limitations associated with selecting a reference limb. Eighteen articles applied a threshold to original research to identify “abnormal” asymmetry, fifteen of which utilised a threshold between 10-15%, yet this threshold was not always supported by appropriate evidence. Asymmetry scores ranged between and within populations from approximate symmetry to asymmetries larger than 15%. When reporting the effects of strength asymmetries, increased injury risk and detriments to performance were often associated with larger asymmetry, however the evidence was inconsistent. Limitations of asymmetry indices should be recognised, particularly those that require selection of a reference limb. Failure to reference the origin of the evidence for an asymmetry threshold reinforces doubt over the use of arbitrary thresholds, such as 10-15%. Therefore, an individual approach to defining asymmetry may be necessary to refine robust calculation methods and to establish appropriate thresholds across various samples and methodologies that enable appropriate conclusions to be drawn.

The effect of muscular strength and strength asymmetry on jumping height in soccer players

BACKGROUND: Lower limb muscular asymmetry is not well studied and may have a negative impact on performance. OBJECTIVE: To estimate how muscular strength and strength asymmetry affect jumping performance in soccer players. METHODS: Twenty-eight male professional soccer players took part in the study. The countermovement jump (CMJ) without arm swing was used to determine jumping height. Muscle strength was measured concentrically at 60 and 300∘/s. RESULTS: The peak moment of the knee extensors was positively and significantly correlated with the CMJ; r= 0.608 at 300∘/s and r= 0.489 at 60∘/s. The asymmetry of the knee flexors between the stronger and weaker leg was negatively and moderately correlated with the CMJ at 300∘/s (r=-0.396). The regression model (R2= 0.474) showed that an increase of 0.18-Nm/kg in the relative strength of the knee extensors at 300∘/s (by one SD) was related to an increase of 3-cm in the CMJ. Reducing the asymmetry of the knee flexors by 6.8 percentage points (by one SD) was related to a rise of 1.7-cm in the CMJ. CONCLUSIONS: Greater strength in the knee extensors, preferably tested at higher velocity, and reduced asymmetry in the strength of the lower hamstring muscles have a statistically significant effect on the CMJ.

The methodology of organizing the training process of athletes and daily regime

The daily regime is the most important component of the training of hand-to-hand athletes, which has a significant impact on the body functioning and its state and the whole training process to competitions. The study substantiates the statement that for strengthening physical and mental health, as well as for the sufficient recovery after training, it is necessary to adhere the established rational daily regime, built taking into account the peculiarities of the training process. A rational daily regime allows athletes to follow the optimal rhythm of activity and, therefore, it is easier to cope with the proposed physical activity before and during the competitions. The article presents the data of the researches concerning the changes in the body functioning of hand-to-hand combatants throughout the day, covers the issues about creating the training process and the daily regime at the period of the preparation for various competitions. Such indicators as the time of motor reaction and its latent and motor components, parameters of the maximum muscle strength and muscle strength asymmetry, the data of the maximum and average blood pressure, heart rate, etc. were measured.The optimal time of the functional state of hand-to-hand athletes was determined, focusing on which the training process and the entire daily regime are created.

451 THE BEST MARKER FOR COGNITION—RELATIVE HANDGRIP STRENGTH, ASYMMETRY OR WEAKNESS?

Introduction Handgrip strength (HGS) is increasingly used to estimate overall muscle strength. Association between low HGS and cognitive decline has been well documented. Recently, McGrath’s team elucidated a new dimension of HGS asymmetry with important implications on physical and cognitive limitations. It is unclear if these effects can be generalised. The Asian working group for sarcopenia (AWGS) has called for ‘special considerations’ due to ‘anthropometric and cultural or lifestyle-related differences’6. Hence, we aim to investigate if HGS asymmetry is associated with cognition in Asians. Methodology We defined sarcopenia by AWGS consensus: HGS <28 kg for men; <18 kg for women. Asymmetry was HGS >10% stronger on either hand; relative HGS was HGS adjusted for BMI. Low cognitive function was defined as MMSE<26. We compared weakness alone, any HGS asymmetry or relative HGS alone and combination of weakness and HGS asymmetry or relative HGS asymmetry. Each model was adjusted for demographic characteristics, hand dominance, obesity, frailty, physical activity, depression and perceived health status. Results 738 Asian subjects participated. Mean age 70.8 ± 0.2 years, 45.1% males, 82.5% Chinese. More than 50% have multimorbidity. 5.4% were frail. Mean BMI 24.4 ± 0.1 kg/m2. Mean HGS 22.6 ± 0.3. 93 (12.7%) had symmetrical HGS and not weak, 59 (7.8%) asymmetrical and not weak, 321 (43.6%) symmetrical and weak, 265 (35.9%) asymmetrical and weak. Mean MMSE scores for weakness alone, asymmetry alone and combined weakness and asymmetry are 26.6 ± 0.1, 26.8 ± 0.2 and 26.5 ± 0.2 respectively. HGS asymmetry alone was not associated with better cognitive function OR 0.66 (95%CI: 0.30–1.44). Combined asymmetry and weakness was non-significantly linked to worse cognition OR 2.14 (95%CI: 0.79–5.82). We found relative HGS to be protective for cognitive decline, OR 0.31 (95%CI: 0.12–0.78, p = 0.012). Conclusion Our study highlights the impact of ethnicity in sarcopenia research. Our population shows association of relative HGS with cognition. Further longitudinal studies are needed.

Effect of Functional Electrical Stimulation Cycling Exercise on Lower Limb Strength Asymmetry in Persons with Multiple Sclerosis

Background: Lower limb strength asymmetry (ie, significant difference between contralateral limbs) has been associated with mobility impairment in persons with multiple sclerosis (MS). However, whether an adaptive exercise modality can be used to modify lower limb strength and potentially improve mobility is unclear. The effect of functional electrical stimulation (FES) cycling on lower limb strength asymmetry in persons with MS with mobility impairment was assessed, and the association between change in lower limb strength asymmetries and changes in functional and self-reported mobility outcomes was explored. Methods: Eight adults with MS (Expanded Disability Status Scale scores, 5.5–6.5) were included. Outcomes included knee extensor and knee flexor strength asymmetry, Timed 25-Foot Walk (T25FW) test, 2-Minute Walk Test (2MWT), Timed Up and Go (TUG) test, and 12-item Multiple Sclerosis Walking Scale (MSWS-12). Participants received 24 weeks (three times per week) of FES cycling or passive leg cycling. Results: The FES condition demonstrated a small decrease in knee extensor (d = −0.33) and knee flexor (d = −0.23) strength asymmetry compared with passive leg cycling. With both groups combined, moderate-to-strong associations were observed between change in knee extensor asymmetry and change in T25FW test time (rs = −0.43), 2MWT time (rs = −0.24), TUG test time (rs = 0.55), and MSWS-12 score (rs = 0.43). Moderate correlations were observed between change in knee flexor asymmetry and change in T25FW test time (rs = −0.31), TUG test time (rs = 0.33), and MSWS-12 score (rs = 0.35). Conclusions: FES cycling may be an efficacious exercise modality for reducing lower limb strength asymmetry and improving mobility in persons with MS.

ASSESSMENT OF THE OCCLUSAL RELATIONS NATURE AT THE STAGES OF ORTHOPEDIC REHABILITATION OF PERSONS WITH PERIODONTAL TISSUE DISEASES COMPLICATED BY DENTITION DEFECTS

Resume. According to epidemiological studies, there is still an increased prevalence of periodontal disease among the population of different regions of the world, with increasing intensity and aggressiveness. Long-term chronic generalized lesions of recurrent and progressive inflammatory-dystrophic process lead to the destruction of alveolar processes, pathological mobility of teeth, tooth loss and dentofacial dysfunctions. One of the most characteristic symptoms of generalized periodontitis is the presence of traumatic occlusion. Depending on the degree of pathological changes in periodontal tissues, the size and topography of dentition defects, the replacement of dentition pathologies should be planned by splint-type orthopedic structures and computerized analysis of occlusal relationships with T-Scan III system. The aim of the study is to improve the effectiveness of orthopedic treatment of periodontal diseases complicated by defects of the dentition with the control of occlusal relationships with a computerized T-Scan III system. Materials and methods. We have examined 87 persons aged between 30 and 69 years with generalized periodontitis of I – III severity, complicated by partial loss of teeth of different sizes and topography, and a control group of the same age in 10 patients with intact dentition and physiological forms of occlusion without clinically diagnosed periodontal diseases. Computerized analysis of occlusion indices was performed by the T-Scan III system. We have investigated the stereotype of functional loads according to the following quantitative and qualitative indicators: the index of asymmetry of force between the parts (%); time of occurrence of the maximum amount of dental contacts (sec); time of disclusion (sec); the presence of premature occlusal contacts on the natural teeth and orthopedic constructions, and the presence of changes in the direction of the trajectory of the total vector of occlusal load. Orthopedic rehabilitation of patients in the case of periodontal diseases of the I-II degree of severity and the presence of small defects of the dentition, we conducted by splint-type orthopedic structures, dental implants, and artificial crowns of our own design with discrete occlusal loading (Licence for Effective Model No 143278, Ukraine, MPK А61С 13/007, u 2019 11487: Artificial Crown with Support on a Dental Implant). Patients with periodontal diseases of the II – III severity, complicated by defects of dentitions with different size and topography, the dental prosthetics has been performed by traditional removable and combined orthopedic splint-type constructions, and removable splint-type dentures of their own design: "Removable Prosthesis of Splint Type" (Licence for Effective Model No 130980 Ukraine, IPC (2006.01) А61С 13/007, u 2018 03039, 10.01.2019). Computerized analysis of occlusion indicators for the patients of I and II clinical groups and the III control group has been performed before and after orthopedic treatment by T-Scan III system. Results of the research. The results of investigation for functional occlusion have demonstrated that the index of relative strength asymmetry between the sides of the dentition in patients with generalized periodontitis complicated by dentition defects increased significantly and led to nonphysiological redistribution of loads compared with indices obtained in patients from control group due to the lack of correspondence for occlusal contacts. These indices are equal to 16.7 ± 3.8% in patients of I group and 18.9 ± 4.8% in group II compared to the similar control indicators – 4.7 ± 1.01%, respectively (p≤0.01). It should be noted that these indicators have differed from the control group indicators according to the severity of the pathological process. Rational prosthetics with removable and non-removable orthopedic structures, including on the base of dental implants, helps to optimize occlusal relations. Conclusions. Occlusographic studies performed in patients with generalized periodontitis having different severity and complicated by partial tooth loss have showed increased index of relative strength asymmetry between the sides of chewing, the presence of premature contacts and incorrect location of the trajectory of the total occlusal load vector. The dynamics of pathological changes in occlusion indices corresponds to the degree of generalized periodontitis, which indicates the necessity of opportune replacement of dentition defects, taking into account the occlusal relations. Rational prosthetics helps to optimize occlusal relations.