Long-Term Changes in Vertical Jump, H:Q Ratio and Interlimb Asymmetries in Young Female Volleyball Athletes.

The present study aimed to examine the changes that occurred in vertical jump and isokinetic dynamometer (ISK) performances at the beginning of a preparatory period (PRE) and at the start of the competitive period (POST). Sixteen U-17 elite female volleyball players, from a national level (15.34 ± 1.19 years; 66.35 ± 7.95 kg; 169.22 ± 24.79 cm), performed bilateral squat jump (SJ), bilateral and unilateral countermovement jump (CMJ) and unilateral ISK tests for knee flexors (Fl) and extensors (Ex) both at 60°/s and at 300°/s. Peak torque (PT) and the hamstring-to-quadriceps (H:Q) ratio were assessed by concentric actions. Asymmetries were calculated by the percentage differences between dominant (DOM) and nondominant legs (NDOM). The paired Student's t-test was used for comparisons at a level of significance of 5%. The effect size was also calculated. A significant increase was found for both SJ (15%; p = 0.004; ES = 0.82) and CMJ (12%; p = 0.017; ES = 0.62). The PT of NDOM flexors at 60°/s was significantly lower than DOM both at PRE (4.6%; p = 0.048; ES = -0.22) and POST (6.3%; p = 0.037; ES = -0.33). The NDOM extensors at 60°/s had a significantly lower PT than DOM at POST (7.0%; p = 0.048; ES = -0.23). Both DOM and NDOM flexors at 60°/s had a PT enhancement at POST related to PRE (6.7%; p = 0.031; ES = 0.51 and 5.6%; p = 0.037; ES = 0.48, respectively). The PT of NDOM extensors at 300°/s increased at POST in comparison to PRE (7.9%; p = 0.038; ES = 0.27). The NDOM at 300°/s had a H:Q ratio higher than DOM both in PRE and POST (8.6%; p = 0.041; ES = 0.37 and 11.6%; p = 0.013; ES = 0.71, respectively), and the highest H:Q ratios were lower than the reference values (<80%). The asymmetry of the unilateral CMJ was higher at POST than at PRE (102%; p = 0.03; ES = 0.81). The PT for the flexors at 300°/s and the H:Q ratio at POST exceeded 10%. In conclusion, a training program of 15 weeks increased the neuromuscular performance of young volleyball athletes, but many H:Q ratios and asymmetries remained out of the normal recommendation. Volleyball professionals should carefully apply an adequate training program to enhance physical fitness performance without increasing the risk of lower limb injuries concurrently.

Immediate changes in post-stroke gait using a shoe lift on the nonaffected lower limb: A preliminary study.

Introduction: Gait impairment is one of the most important post-stroke complications and is associated with reduced mobility, limitations in activities of daily living and decreased quality of life. Gait recovery is an important goal in post-stroke rehabilitation and shoe lifts have been used on the nonaffected lower limb (NLL) to reduce compensatory strategies such as vaulting, pelvic hiking and hip circumduction during the swing phase of the affected lower limb. Moreover, in clinical practice shoe lifts seem to reduce tripping and the risk of falls.Objective: Evaluate walking speed and functional mobility with and without a 1.5 cm shoe lift under the non-affected lower limb in post-stroke gait.Methods: Forty-two subjects with hemiparesis after stroke were evaluated on a single day, under two conditions: with and without a 1.5 cm shoe lift. The assessment sequence was randomized and clinical tests (Ten-meter walk Test - 10MWT and Timed Up and Go - TUG) were performed one after the other.Results: There was a significant increase in walking speed in the 10MWT and shorter TUG times, with mean differences of 0.78 (CI95% 0.15-1.41, P ≤ 0.001, EF = 0.55) and 0.57 seconds (-0.11-1.25, P = .022, EF = 0.35), respectively.Conclusion: The results showed that the immediate use of 1.5 cm shoe lifts seems to improve gait speed and functional mobility in chronic stroke patients. Further studies should focus on understanding the kinematics strategies and gait pattern alterations caused by shoe lifts under the NLL of post-stroke individuals.

Differences in Handgrip Strength-Endurance and Muscle Activation Between Young Male Judo Athletes and Untrained Individuals.

Purpose: The aim of this study was to compare strength-endurance handgrip performance and muscle coactivation between judo athletes and untrained young males. Method: The sample was 38 judo athletes and 38 untrained young males, between 12 and 15 years-old. Maturational status was evaluated by age at peak height velocity. A maximal isometric handgrip test (three 5-s repetitions, with 90-s intervals) and an isometric strength-endurance handgrip test (ten 10-s all-out isometric handgrip repetitions, 20-s intervals) was conducted in dominant (D) and nondominant (ND) hands, using a dynamometer with EMG monitor to detect muscle activation. Results: ANCOVA analysis, controlling for maturational status, showed that judo athletes had higher values of maximal absolute (D = 33.6 ± 8.9 kgf vs 29.1 ± 9.0 kgf; ND = 33.8 ± 9.9 kgf vs 28.1 ± 8.1 kgf) and relative strength to body mass (D = 0.64 ± 0.12 kg/kgf vs 0.57 ± 0.13 kg/kgf; ND = 0.64 ± 0.16 kg/kgf vs 0.56 ± 0.14 kg/kgf). Moreover, judo athletes presented lower strength mean fatigue index (33.2 ± 6.9 % vs 37.9 ± 8.7 %) and muscle coactivation (48 ± 19.8 % vs 57.5 ± 22 %), only in the dominant hand, during the isometric strength-endurance handgrip test. During all repetitions of isometric endurance test there were no group or interaction between factors effects for absolute strength, relative strength and muscle coactivation. Conclusion: In summary, judo athletes present higher maximal absolute and relative strength and strength-endurance performance, concomitantly with decreased muscles co-activation (primary in dominant hand) during handgrip tests.

The Effects of Different Exergame Intensity Training on Walking Speed in Older Women.

Objective: It is not known if the intensity in which exergames are performed can change gait parameters at different walking speeds. This study was designed to determine if a training program based on exergame exercises performed at different intensities (moderate vs. vigorous) influences walking speed and gait parameters in older adult women. Methods: After applying the inclusion criteria, 20 participants (69.5 ± 5.4 years) were randomized into two groups: moderate (11-13 perceived exertion) and vigorous (14-16 perceived exertion). Walking speed and gait parameters at self-selected walking speed (SSWS) and maximal walking speed (MWS) were evaluated before and after 3 months of exergame training. The walking speed and gait parameters were measured with an instrumented walkway. The walking speed reserve (WSR) was calculated as a difference and ratio. Results: There was pre-to-post effect of walking speed at self-selected walking pace (pre = 112.1 ± 16.4 cm.s-1; post = 124.8 ± 16.4 cm.s-1), in WSR calculated as ratio (pre = 1.35 ± 0.08; post = 1.28 ± 0.09), in a number of gait parameters at SSWS (step length, stride length, stride velocity, step time, stride time, swing time, stance time, single support, double support, gait cycle time, and cadence) and at MWS (step time, stride time, swing time, single support, double support, gait cycle time, and cadence). Conclusion: Irrespective of the exercise intensity, exergame training improved walking speed only at a self-selected walking pace and some gait parameters at self-selected and MWS in older women.

Biomechanic of ballroom dance: corporate adaptations with different footwear / Biomecânica da dança de salão: adaptações corporais com diferentes calçados

ABSTRACT The aim of this study was to compare the joint amplitude, spine angulation and displacement of the center of mass during the execution of gafieira samba with and without high heels at different speed. In addition, the reproducibility of the movement was tested. Fifteen experienced dancers performed a sequence of gafieira samba steps under the conditions: high heels (7.5cm) and flats at two speeds according to the beat of music (72 and 96bpm). Kinematic analysis was performed on the Vicon® system with 11 cameras (100 Hz). Twenty-one reflective markers were positioned over the participants' bodies to calculate the center of mass and joint angles of the lower limbs and spine. Reproducibility was determined by the intraclass correlation coefficient and the comparison between conditions was tested by a Two-way Analysis of Variance, with the factors footwear and speed. The results indicated to a moderate to very high reproducibility in all variables analyzed. No differences were found between lumbar curvature, thoracic and displacement of the center of mass. There was no interaction between types of footwear and step execution speed, but analyzing the main factors, there was a decrease in the left ankle plantiflexion angle with increasing speed. The ankle angles showed a significant decrease under the condition flats when compared to high heels. In conclusion, high heels do not alter lumbar curvature, displacement of the center of mass and knee and hip joint amplitude in the execution of gafieira samba.

RESUMO O objetivo deste estudo foi comparar a amplitude articular, angulação da coluna e deslocamento do centro de massa durante execução do samba de gafieira com e sem salto alto em diferentes velocidades. Adicionalmente, a reprodutibilidade do movimento foi testada. Quinze dançarinas experientes realizaram uma sequência de passos de samba de gafieira nas condições: salto alto (7,5 cm) e sapatilha em duas velocidades de execução de acordo com o compasso das músicas (72 e 96bpm). A análise cinemática foi realizada no sistema Vicon® com 11 câmeras (100 Hz). Vinte e um marcadores reflexivos foram posicionados sobre o corpo das participantes a fim de calcular o centro de massa e ângulos articulares dos membros inferiores e coluna. A reprodutibilidade foi determinada pelo coeficiente de correlação intraclasse e a comparação entre condições foi testada por uma análise de variância Two way, com os fatores calçados e velocidade. Os resultados indicaram para uma reprodutibildade de moderada a muito alta em todas as variavéis analisadas. Não foram encontradas diferenças entre as curvaturas da lombar, torácia e deslocamento do centro de massa. Não houve interação entre tipos de calçado e velocidade de execução dos passos, porém analisando os fatores principais, ocorreu uma diminuição do ângulo de plantiflexão do tornozelo esquerdo com o aumento da velocidade. Os ângulos de tornozelo apresentaram diminuição significativa em situação do uso de sapatilhas, quando comparados ao salto. Conclui-se que o salto alto não altera a curvatura da lombar, deslocamento de centro de massa e amplitude articular do joelho e quadril na execução do samba de gafieira.