RELIABILITY OF A SIMPLE NOVEL FIELD TEST FOR THE MEASUREMENT OF PLANTAR FLEXOR MUSCLE STRENGTH

ABSTRACT Introduction When a person is in a standing position, the plantar flexor muscles are involved in most static and dynamic body movements. Objectives The aim of this study was to investigate the trial to trial and factorial reliability of measuring the contractile characteristics of PF muscles using a simple novel field test. Methods The sample consisted of 452 healthy subjects, 120 male and 332 female. The research was conducted by means of the trial to trial testing method, using isometric dynamometry performed in field conditions. ANOVA was used to estimate the differences among the trials, Cronbach’s alpha and interclass correlation to estimate the correlations among the trials, and principal component analysis to evaluate the contribution of each trial to overall variability. Results The main findings of this study are that trials differed significantly (p<0.000) for maximal force (Fmax) and maximal rate of force development (RFDmax), indicating that the three procedural trials were necessary. The trials were highly correlated (Fmax, RFDmax, r>0.9), proving that measuring was reliable, and the factorial analysis separated the second and third trials, the second trial accounting for most of the total variability. Conclusions The simple novel field test for the measurement of plantar flexor contractile characteristics recommended by this study proved to be as highly reliable as laboratory testing, but was easy to perform in conditions outside of scientific or diagnostic institutions, which greatly facilitates the work of scientists, coaches and professionals. Level of Evidence II; Diagnostic Studies – Investigating a diagnostics test.

Sex-Based Differences in Tensiomyography as Assessed in the Lower Erector Spinae of Healthy Participants: An Observational Study

Background: Although there is mounting evidence on sex-linked differences in paraspinal muscle function, it is unknown whether sex-based variations in mechanical and contractile characteristics of the lumbar erector spinae (LES) can be monitored noninvasively in healthy participants at rest using tensiomyography (TMG). Hypothesis: Sex-specific effects in muscle displacement (Dm) and velocity of muscle deformation (Vd) will be observed via TMG assessed in the LES. Study Design: Observational study. Level of Evidence: Level 3. Methods: LES response was measured in a relaxed state in 40 healthy adults (20 females). Possible differences between the conditions were investigated using mixed-model analyses of variance. Two-stage hierarchical linear regression analyses were performed to predict the outcome of TMG Dm and Vd based on participant sex. Results: There were significant main effects of sex with large effect sizes for both TMG parameters, resulting from lower mean values in women compared with men (Dm, P < 0.01; Vd, P < 0.01). In contrast, neither the main effect of side (left vs right LES) nor the interaction between the side and sex reached significance (all P > 0.3). Introducing the sex variable in stage 2 of the regression analyses significantly improved the prediction of the TMG parameters (all ∆R2 ≥ 0.18; all P < 0.01; all f2 ≥ 0.29). Conclusion: Sex-based differences in muscle stiffness and contractile characteristics could be observed by TMG on LES muscles in healthy individuals at rest. The data suggest that these disparities are not exclusively attributable to anthropometric measures but may be linked to intrinsic sex-based differences in skeletal muscle characteristics. Clinical Relevance: We recommend implementing TMG in a clinical setting using the obtained results as a basis to factor for the patient’s biological sex when assessing effects of therapeutic/exercise regimens aiming at the optimization of myofascial tissue regeneration and performance.

HANDGRIP MUSCLE FORCE CHARACTERISTICS WITH GENERAL REFERENCE VALUES AT CHELYABINSK AND BELGRADE STUDENTS

The Aim. The aim of this paper is to define the contractile characteristics of maximal isometric handgrip force and to establish possible differences between the students of the Universities of Chelyabinsk and Belgrade. The secondary aim is to create a practically applicable initial model in order to explore the mentioned characteristics in the future. Material and methods. For the purposes of this research, the overall sample of 225 subjects was tested. 91 subjects were from Russia and 134 were from Serbia. The results were gathered using a strain gage and a standardized isometric handgrip test protocol. The contractile properties of HG muscle force were measured in relation to three different contractile dimensions: the maximal muscle force (Fmax), the maximal explosive muscle force (RFDmax), the time need for achieving maximal (tFmax) and maximal explosive (tRFDmax) muscle force. Results. This study has shown that there are no generally statistically significant differences for all observed variables of HG contractile characteristics between tested Russian and Serbian students. Based on the results of the present study, six different models of the equation for evaluation of HG contractile characteristics of female and male students, i.e. young adults, were made. All defined models are highly statistically significant, accurate and sensitive in the prediction of the general distributive position of an individual or particular group of subjects in relation to the measured contractile characteristics. Conclusions. The obtained results can generally indicate the stability of potential to exert the given contractile characteristic in relation to the population of similar evolutionary (Slavs) at different geographical background.

QUALITATIVE AND QUANTITATIVE EVALUATION OF THE CHARACTERISTICS OF THE ISOMETRIC MUSCLE FORCE OF DIFFERENT MUSCLE GROUPS IN CADET JUDO ATHLETES: A GENDER-BASED MULTIDIMENSIONAL MODEL

The aim of this paper is to define the initial quantitative and qualitative multidimensional model for evaluating basic contractile characteristics of isometric muscle force in systematically trained and selected cadet judo athletes. In this research absolute values of the obtained results, and values derived by relativization of absolute values in relation to skeletal muscle mass (SMM) were considered. The basic method used in this research was laboratory testing. All data sampling was performed by the dynamometry method, using tensiometric probes. The research sample in this study consisted of 21 cadet judo athletes, of which 14 were male and 7 were female. All measurements were performed using standardized testing procedures on the following muscle groups: flexor muscles of the left (HGL) and the right hand (HGR), back (DL) and leg extensor muscles (LE) and ankle joint plantar flexor muscles (PF). Based on the obtained results, separate multidimensional mathematical models for the estimation of contractile potential and development level were defined for both basic characteristics of isometric muscle force: maximal isometric muscle force (Fmax) and maximal explosive isometric muscle force (RFDmax). A qualitative assessment of contractile potential for each of the tested muscle groups, i.e. variables, was enabled by defining standard values for 7 distinct preparedness levels for both basic isometric muscle force contractile characteristics of male and female cadet judo athletes.

Taurine and Methylprednisolone Administration at Close Proximity to the Onset of Muscle Degeneration Is Ineffective at Attenuating Force Loss in the Hind-Limb of 28 Days Mdx Mice

An increasing number of studies have shown supplementation with the amino acid taurine to have promise in ameliorating dystrophic symptoms in the mdx mouse model of Duchenne Muscular Dystrophy (DMD). Here we build on this limited body of work by investigating the efficacy of supplementing mdx mice with taurine postnatally at a time suggestive of when dystrophic symptoms would begin to manifest in humans, and when treatments would likely begin. Mdx mice were given either taurine (mdx tau), the steroid alpha methylprednisolone (PDN), or tau + PDN (mdx tau + PDN). Taurine (2.5% wt/vol) enriched drinking water was given from 14 days and PDN (1 mg/kg daily) from 18 days. Wild-type (WT, C57BL10/ScSn) mice were used as a control to mdx mice to represent healthy tissue. In the mdx mouse, peak damage occurs at 28 days, and in situ assessment of contractile characteristics showed that taurine, PDN, and the combined taurine + PDN treatment was ineffective at attenuating the force loss experienced by mdx mice. Given the benefits of taurine as well as methylprednisolone reported previously, when supplemented at close proximity to the onset of severity muscle degeneration these benefits are no longer apparent.