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The aim of this study was to examine the effect of attentional focus instructions on the biomechanical variables associated with the risk of anterior cruciate ligament injury of the knee joint during a drop landing task using a time series analysis. Ten female volleyball players (age: 20.4 ± 0.8 years, height: 169.7 ± 7.1 cm, mass: 57.6 ± 3.1 kg, experience: 6.3 ± 0.8 years) performed landings from a 50 cm height under three different attentional focus conditions: (1) external focus (focus on landing as soft as possible), (2) internal focus (focus on bending your knees when you land), and (3) control (no-focus instruction). Statistical parameter mapping in the sagittal plane during the crucial first 30% of landing time showed a significant effect of attentional focus instructions. Despite the similarity in landing performance across foci instructions, adopting an external focus instruction promoted reduced vertical ground reaction force and lower sagittal flexion moment during the first 30% of execution time compared to internal focus, suggesting reduced knee loading. Therefore, adopting an external focus of attention was suggested to reduce most biomechanical risk variables in the sagittal plane associated with anterior cruciate ligament injuries, compared to internal focus and control condition. No significant differences were found in the frontal and horizontal planes between the conditions during this crucial interval. [ABSTRACT FROM AUTHOR]

The aim of the present study was to examine the effects of attentional focus instructions on acute changes in the transverse relaxation time (T2) of the femorotibial cartilage and in cartilage volume during repeated drop‐jump landings. Ten healthy females (Mage = 20.4 ± 0.8 years) performed a drop landing task from a 50 cm high box over the course of 3 days (50 repetitions each day) across three attentional focus conditions: external focus (EF: focus on landing as soft as possible), internal focus (IF: focus on bending your knees when you land), and control (CON: no‐focus instruction), which was counterbalanced across focus conditions. T2 mapping and the volume of femorotibial cartilage were determined from magnetic resonance imaging scans at 1.5 T for the dominant knee before and after completing the drop landings in each attentional focus condition per day. Results indicated a smaller change in cartilage T2 relaxation time and volumetry in the central load‐bearing lateral cartilage under the EF, compared to IF and CON. Moreover, the change in T2 and cartilage volume was greater for lateral tibial cartilage as compared to femoral cartilage and was independent of attentional focus instructions. No significant acute quantitative changes were observed in the medial compartment. The peak vertical ground reaction force was found to be the lowest under the EF, compared to IF and CON. These findings suggest that external focus of attention may reduce cartilage load, potentially aiding in the control or management of cartilage injuries during landing in female athletes. [ABSTRACT FROM AUTHOR]

The performance assessment of relevant biomechanical factors is essential for appropriate age-related training progression in volleyball spike (VS). This study aimed to investigate the differences in upper limbs' (a) range of motion (ROM), (b) angular velocities, and (c) muscular activity during VS among under 16- (U-16), under 18- (U-18), and under 20- (U-20) year-old female volleyball players. The kinematic variables of the spike performances were recorded using six optoelectronic cameras (Vicon Motion system, UK). Additionally, the wireless Trigno system (Delsys, USA) was used to record the electromyographic signals. The one-way ANOVA (1d SPM analysis) exhibited a significantly greater wrist internal rotation (p <.001), wrist adduction velocity (p <.001), and palmaris longus activity (p <.001) in the acceleration phase in U-20, compared to the U-16 group. Additionally, the U-20 and the U-18 players portrayed a significantly greater shoulder external rotation (p <.001) and internal angular velocity (p =.035) relative to the U-16 group. A significantly greater pectoralis major (p <.001), biceps brachii (p <.001), and anterior deltoid (p <.001) activity was observed in the U-20 group, compared to younger groups. This study suggests that older players employ more upper limb muscular activities during spike with the presence of blocks, which enables them to hit the ball with greater velocities and direct the ball in their desired direction through increased wrist ROMs. [ABSTRACT FROM AUTHOR]

Problem statement: Given the importance of achieving optimal performance in sports, monitoring, predicting, and enhancing sports performance is an important element for coaches and trainers. This study aimed to investigate the correlation between the force-time (F-T) curve variables of the concentric phase of the countermovement jump (CMJ) and the volleyball spike jump (VSJ) with the VSJ height in young female volleyball players. Material and Methods: Forty-two sub-elite young female volleyball players performed three VSJ and three CMJ in game-simulated circumstances on two 40cmX60cm Kistler force platforms (9290AD, Winterthur, Switzerland). Results: Pearson's product-moment correlations showed no significant correlation between the height of the VSJ and the F-T curve variables (rmax = .25) of the CMJ. The results of the multiple regression analysis showed no significant contribution of F-T variables of the CMJ in the prediction of the VSJ height (p = .835). Peak Force (r = .46, p = .002), Relative Peak Force (r = .31, p = .049), Peak Power (r = .56, p < .001), Relative Peak Power (r = .50, p = .001), and RSImod (r = .39, p = .010) of the VSJ had significant correlation with VSJ height. Discussion: The findings of this study support the importance of selecting an appropriate sport-specific jump test for assessment, monitoring, and predicting jump performance. Conclusions: Specifically, to the results of this study, coaches and trainers may use the F-T curve variables of the CMJ to assess the explosive strength of the lower limbs, but not for the prediction of VSJ height. In addition, measures of peak force and peak power during the VSJ, whether absolute or relative, were found to contribute significantly to the VSJ height. [ABSTRACT FROM AUTHOR]

The gut microbiome (GM) of rheumatic arthritis (RA) patients is often altered in composition and function. Moreover, methotrexate (MTX), one of the most frequently used disease-modifying antirheumatic drugs, is known to negatively affect GM composition. The modulation of immune system activity is one of the therapeutic benefits of probiotics. The aim of the current investigation was to determine the impact of MTX therapy combined with one of the Lactobacillus strains, Lactoplantibacillus plantarum LS/07 (LB), on adjuvant arthritis (AA) in rats. Methods focused on biometric and inflammatory parameters in AA, particularly on plasmatic levels of IL-17A, MMP-9, and MCP-1, and the activities of gamma-glutamyl transferase in the spleen and joints were applied. Enhancing the effect of MTX, LB positively influenced all biometric and inflammatory parameters. The findings of the present study may be of help in proposing novel therapeutic strategies for RA patients. [ABSTRACT FROM AUTHOR]

This study investigated the differences between force-time (F-T) curve variables of volleyball spike jumps (SpJ) in simulated real-game conditions, including timing, force measurements, velocity, and power among four groups of young sub-elite female volleyball players (Under-14, −16, −18 and −20). The 1-way ANOVA revealed that U-18 and U-20 players produced significantly higher values of relative peak rate of force development (p = 0.015), average rate of force development (p = 0.046), relative power (p = 0.005), peak velocity (p = 0.001) and ultimate jump heights (p = 0.001), in comparison with U-14 and U-16 peers. Correlation analysis showed a significant correlation between the relative peak rate of force development, relative average rate of force development, and relative peak power with SpJ jump height in all age groups. Time series analysis of relative applied peak forces indicated that the U-18 and U-20 players reached their relative maximum applied forces significantly earlier than U-14 and U-16 players (p = 0.021). This study suggests that the increase in the height of the SpJ across age groups in young female players is mainly related to achieving faster time to peak force by increased concentric jump-phase peak velocity. Therefore, the time to peak force can be considered as the significant kinetic contributor to higher SpJ height. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) and its animal model adjuvant arthritis (AA) are inflammatory diseases characterized by chronic inflammation, systemic oxidative stress and disturbed mitochondrial bioenergetics of skeletal muscle. The present study aimed to evaluate the effects of coenzyme Q10 - CoQ10 (100 mg/kg b.w.), omega-3-polyunsaturated fatty acids - 1-3-PUFA (400 mg/kg b.w.) and their combined treatment in AA on impaired skeletal muscle mitochondrial bioenergetics, inflammation and changes in levels CoQ9 and CoQ10 in plasma. Markers of inflammation (C-reactive protein, monocytechemotactic protein-1), antioxidant capacity of plasma, respiratory chain parameters of skeletal muscle mitochondria and concentrations of CoQ9 and CoQ10 in plasma and in muscle tissue were estimated. Treatment of the arthritic rats with CoQ10, 1-3-PUFA alone and in combination partially reduced markers of inflammation and increased antioxidant capacity of plasma, significantly increased concentrations of coenzyme Q in mitochondria and improved mitochondrial function in the skeletal muscle. Combined treatment has similar effect on the mitochondrial function as monotherapies; however, it has affected inflammation and antioxidant status more intensively than monotherapies. Long-term supplementary administration of coenzyme Q10 and 1-3-PUFA and especially their combination is able to restore the impaired mitochondrial bioenergetics and antioxidant status in AA. [ABSTRACT FROM AUTHOR]