Reliability and validity of My Jump 2 application to measure lower limb vertical stiffness of college students / 中国组织工程研究

BACKGROUND:Confirming the reliability and validity of the My jump 2 application for measuring lower limb vertical stiffness may offer the possibility of it as an alternative to the Kistler three-dimensional force platform for measuring lower limb stiffness. OBJECTIVE:To verify the reliability and validity of the My Jump 2 application in measuring lower limb vertical stiffness of college students. METHODS:The drop jump data of the participants were collected through the Kistler three-dimensional force platform and the My Jump 2 application,and the vertical stiffness of the participants'lower limb vertical stiffness was calculated.The intraclass correlation coefficient was used to analyze the data measured by the My Jump 2 application and the Kistler three-dimensional force platform,attempting to verify the reliability of the My Jump 2 application.The bias and average between the two devices were drawn into a Bland-Altman diagram to verify the consistency between the two test methods.Finally,the test-retest reliability of the My Jump 2 applications at 30 cm and 40 cm was analyzed using the Cronbach's alpha(α)and coefficient of variation.Pearson product-moment correlation was used to analyze the correlation of My Jump 2 applications. RESULTS AND CONCLUSION:My Jump 2 application has high reliability and validity when measuring the vertical stiffness of the lower limb.At the same time,due to its advantages of low cost,convenient portability and field testing for large samples,it can be used as an alternative to the Kistler three-dimensional force platform to test the vertical stiffness of the lower limb in college students and similar populations.

Biomechanical characteristics of the lower limbs of athletes after anterior cruciate ligament reconstruction during bilateral vertical jumping / 中国组织工程研究

BACKGROUND:At present,postoperative timing or subjective criteria by clinicians are commonly employed to determine the return-to-sport timing for patients undergoing anterior cruciate ligament reconstruction.Unfortunately,these criteria do not adequately consider the biomechanical deficits in patients following anterior cruciate ligament reconstruction. OBJECTIVE:To explore the lower extremity kinematic and kinetic characteristics of athletes after anterior cruciate ligament reconstruction during bilateral vertical jumping. METHODS:Twenty athletes undergoing anterior cruciate ligament reconstruction and twenty healthy athletes,aged 20-24 years,were recruited in Wuhan Sports University from December 2021 to December 2022.All the 40 subjects underwent a bilateral vertical jumping test.The kinematic and dynamic characteristics of the lower limbs at propulsion phase,initial landing time and peak vertical ground reaction force moment. RESULTS AND CONCLUSION:At the initial landing time,the athletes undergoing anterior cruciate ligament reconstruction showed higher hip flexion angle(P=0.031)and lower ankle plantar flexion angle(P=0.018)on the operated side compared with the healthy athletes.At the peak vertical ground reaction force moment,the athletes undergoing anterior cruciate ligament reconstruction had higher hip flexion angle(P=0.016),lower hip abduction angle(P=0.019),lower knee flexion angle(P=0.025),higher knee external rotation angle(P=0.030),and higher ankle external rotation angle(P=0.042)on the operated side compared with the healthy athletes.At the peak vertical ground reaction force moment,the athletes undergoing anterior cruciate ligament reconstruction showed lower knee extension moment(P=0.036),lower knee internal rotation moment(P=0.016),lower hip abduction moment(P=0.004),higher hip extension moment(P=0.040),and higher hip external rotation moment(P=0.005)on the operated side compared with the healthy athletes.To conclude,the athletes undergoing anterior cruciate ligament reconstruction exhibit a stiff landing pattern,in which the knee load on the operated side tends to shift to the hip joint,and show inadequate control of lower limb rotational stability.Therefore,detection and correction of abnormal biomechanical characteristics should be part of the rehabilitation after anterior cruciate ligament reconstruction.

A meta-analysis of the effect of post-activation potentiation on athletic performance after activation of lower-extremity relative strength levels / 中国组织工程研究

OBJECTIVE:The effect of post-activation potentiation on sports performance is characterized by increased muscle mobility and increased rate of muscle force generation.In this paper,Meta-analysis is used to quantitatively evaluate the effects of post-activation potentiation on sprint speed,jumping performance,and kinetic parameters(peak impulse,peak power,maximum ground reaction force,rate of force generation,etc.)after activation of relative strength levels in the lower limbs. METHODS:Electronic databases such as CNKI,WanFang,Web of Science,PubMed,and Medline were retrieved for randomized control,random crossover,or clear grouping according to the relative strength levels of the lower limbs(non-randomized controls)on the post-activation potentiation effect after activation induced by the relative strength level of the lower limbs.Free weight equipment and rapid telescopic compound exercises were used as main intervention methods in each group.The publication time of the literature was from the inception of each database until August 5,2023.Endnote software was used to manage the literature.Literature quality assessment was conducted using the PEDro scale for randomized controlled trials and ROBINS-I 2.0 standards for non-randomized controlled trials.Revman5.4 and Stata15.0 software were used to conduct publication bias evaluation,subgroup analysis and sensitivity analysis of the extracted data,and forest plots were produced for Meta-analysis. RESULTS:Eleven documents(seven randomized controlled trials and four non-randomized controlled trials)were finally included,including 216 subjects.Overall,the methodological quality of the literature was high.According to the grouping standard of 1-repetition maximum/body mass>2 for the strong group and 1-repetition maximum/body mass≤2 for the normal group,there were 99 subjects in the strong group and 117 subjects in the normal group,all of whom were male.The positive effect of post-activation potentiation on sprint performance in the strong group was significantly higher than that in the normal group[standardized mean difference(SMD)=-1.34,95%confidence interval(CI):-1.74 to-0.93,P<0.000 01];the positive effect of post-activation potentiation on vertical jump height showed no significant difference between the strong and normal group(SMD=0.30,95%CI:-0.07 to 0.66,P=0.11);the positive effect of post-activation potentiation showed no significant difference between the strong and normal groups in terms of peak impulse(SMD=-0.07,95%CI:-0.62 to 0.47,P=0.61],peak power(SMD=0.21,95%CI:-0.29 to 0.72,P=0.12),maximum ground reaction force(SMD=0.31,95%CI:-0.20 to 0.81,P=0.16)and force generation rate(SMD=0.36,95%CI:-0.11 to 0.82,P=0.39). CONCLUSION:The post-activation potentiation effect in the strong group can significantly increase the short-distance sprint speed.The potentiation effect after activation of the relative strength level of the lower limbs has similar effects on the kinematic and kinetic parameters,including explosive vertical jump height,peak impulse,peak power,maximum ground reaction force and force generation rate.

Effect of blood flow restriction combined with low-intensity plyometric jump training on functional ankle instabil-ity / 中国康复理论与实践

Objective To investigate the effect of blood flow restriction combined with low-intensity plyometric jump training(LI-PJT+BFR)on lower limb dynamic postural control of functional ankle instability(FAI)in college students. Methods From March to May,2023,40 FAI college students were recruited from Xi'an Physical Education University,and randomly divided into high-intensity plyometric jump training(HI-PJT,n = 14)group,low-intensity plyomet-ric jump training(LI-PJT,n = 13)group and LI-PJT+BFR group(n = 13).All the groups finished the six-week corresponding training.The maximum voluntary isometric contraction(MVIC)of tibialis anterior,peroneus lon-gus,lateral head of gastrocnemius,gluteus maximus,vastus lateralis,biceps femoris and semitendinosus were measured,and the root mean square(RMS)of electromyography of these muscles was measured during the sin-gle-leg landing(SLL),using wireless surface electromyography before and after intervention.Moreover,they were assessed with Y-balance test and Cumberland Ankle Instability Tool(CAIT). Results MVIC and RMS of the target muscles improved after intervention in all the groups(t>2.218,P<0.05),except MVIC and RMS of peroneus longus,gluteus maximus,biceps femoris and semitendinosus in LI-PJT group,and RMS of peroneus longus in LI-PJT+BFR group;and MVIC and RMS of the target muscles were the least in LI-PJT group(F>3.262,P<0.05),except those of peroneus longus.The extension scores of Y-balance test and the total score improved after intervention(t>2.485,P<0.05),and they were the least in LI-PJT group(F>5.042,P<0.05).The CAIT score improved after intervention(t>5.227,P<0.001),and it was the least in LI-PJT group(F = 4.640,P<0.05). Conclusion LI-PJT+BFR could improve lower limb dynamic postural control of FAI college students,which is similar to HI-PJT.

Effects of acute caffeine ingestion on the physical performance of amateur american football athletes / Efeitos da ingestão aguda de cafeína no desempenho de atletas amadores de futebol americano

ABSTRACT The aim of this study was to investigate the effects of acute caffeine ingestion (5 mg.kg-1) on jump, isometric strength and repeated sprint performance in amateur American football athletes. Twelve players (24.6 ± 3.66 years and 115.18 ± 24.35 kg of body weight) ingested a dose of caffeine (5 mg.kg−1) or placebo 60 min prior to a testing session consisting of: 1) countermovement jump (CMJ); 2) isometric mid-tight pull (IMTP); and 3) 3-line drills (200-yd shuttle runs with a 2-minute rest between sprints). Two testing sessions were performed using a double-blind, counterbalanced, crossover design during a pre-season training camp. Results indicated: Caffeine ingestion improved CMJ performance (p = 0.035), but no differences were observed on IMTP strength (p = 0.22) and line drill performance (total time: p = 0.65, and fatigue (%): p = 0.75) when compared to placebo condition. Conclusion: Acute caffeine ingestion improved jump performance, but not isometric strength and repeated sprint with change-of-direction performance in amateur American Football athletes.

RESUMO O objetivo deste estudo foi investigar os efeitos da ingestão aguda de cafeína (5 mg.kg-1) no salto, força isométrica e desempenho de sprints repetidos em atletas amadores de futebol americano. Doze jogadores (24,6 6 ± 3.66 anos e 115,18 ± 24.35 kg de peso corporal) ingeriram uma dose de cafeína (5 mg.kg−1) ou placebo 60 minutos antes de uma sessão de testes que consistia em: 1) Salto contramovimento (CMJ); 2) Meio-agachamento isométrico (IMTP); 3) Corrida de agilidade em L (3-line drill = corrida de agilidade de 200 jardas com 2 minutos de repouso entre os sprints). Duas sessões de teste foram realizadas usando um delineamento cruzado duplo-cego durante o período de pré-temporada de treinamento. Resultados indicaram: A ingestão de cafeína melhorou o desempenho do CMJ (p = 0,035), mas não foram observadas diferenças na força no IMTP (p = 0,22) e no desempenho do exercício de agilidade em L (tempo total: p = 0,65 e fadiga (%): p = 0,75) quando em comparação com a condição placebo. Conclusão: A ingestão aguda de cafeína melhorou o desempenho no salto, mas não na força isométrica e no desempenho de sprints repetidos com mudança de direção em atletas amadores de futebol Americano.

Perfil de estado de ánimo y autoeficacia percibida en tareas de salto con contramovimiento en atletas cubanos de élite

Introducción: El estado de ánimo y la autoeficacia presentan estrecha relación con el rendimiento deportivo. En atletismo, contar con un control exhaustivo del entrenamiento físico y mental supone asentar las bases del máximo rendimiento, siendo el salto vertical un excelente elemento de control. Sin embargo, su relación con los aspectos psicológicos durante los entrenamientos se ha divulgado poco en la literatura. Este artículo tiene como objetivo analizar la relación entre el perfil de estado de ánimo y la autoeficacia durante saltos verticales en deportistas juveniles de la preselección nacional cubana de atletismo. Método: Se evaluó el estado de ánimo y la autoeficacia antes de ejecutar un salto con contra movimiento (CMJ), presentándose el valor de 40 cm como elemento de máximo rendimiento en atletas de élite. Resultados: Se encontró correlación significativa entre el factor ansiedad del POMS y variables del CMJ. Además, se encontró correlación negativa entre la autoeficacia y la ansiedad, aunque no significativa (p > .05). Conclusiones: Los deportistas con un estado de ánimo de puntuación media de ansiedad, aunque no sobreelevada (puntaje 2 sobre 4) antes de la ejecución de saltos verticales, obtuvieron mejores resultados de CMJ, consiguiendo un mayor rendimiento tanto en la altura de salto, como en la velocidad, fuerza y potencia del salto. Sin embargo, no se hallaron correlaciones significativas entre la autoeficacia y el estado de ánimo, ni con variables de salto.

Introduction: Both mood and self-efficacy seem to be components closely related to the athlete's performance. In athletics, to have an exhaustive control of training from the physical and mental point of view is to lay the foundations for sporting success. Exercises such as the vertical jump are an excellent element of control of athletic performance. However, their relationship with psychological aspects during training has been little reported in the literature. Our objective was to analyze the relationship between the mood profile and self-efficacy during vertical jumps in youth athletes of the Cuban national preselection of athletics. Method: Mood and self-efficacy were evaluated before executing a countermovement jump (CMJ), presenting the 40-cm value as the element of maximum success in elite athletes. Results: A significant correlation was found between anxiogenic mood and vertical jump variables. In addition, a negative correlation was found between self-efficacy and anxiety, although not significant (p > .05). Conclusions: Athletes with a medium anxiety score mood although not overelevated (score 2 out of 4) before the execution of vertical jumps obtained better CMJ results, achieving higher performance in both jump height, speed, strength and power of the jump. However, no significant correlations were found between self-efficacy and mood, nor with the jumping variables.

Morphological Characteristics of Elite Female Volleyball Players Under 19 / Características Morfológicas de Jugadoras de Voleibol de Élite Menores de 19 Años

SUMMARY: The aim of the article is to determine the differences in morphological characteristics and jumping abilities between female volleyball players who play for different national teams. The sample consists of 48 elite female volleyball players from four different national teams which participated in European championship qualifications. The variables studied were: body height, mass, body mass index, standing reach and spike reach. The results show differences in body mass index, standing reach and spike reach. These differences are related to the needs of the different positions with regard to the actions they execute. In conclusion morphological parameters are important components of performance in many sports (volleyball). Different sports disciplines require different body parameters and body structure for maximum performance.

El objetivo del artículo fue determinar las diferencias en las características morfológicas y habilidades de salto entre las jugadoras de voleibol que juegan en diferentes selecciones nacionales. La muestra consta de 48 jugadoras de voleibol de élite de cuatro equipos nacionales diferentes que participaron en las clasificaciones del campeonato europeo. Las variables estudiadas fueron: altura corporal, masa, índice de masa corporal, alcance de pie y alcance de remate. Los resultados muestran diferencias en el índice de masa corporal, el alcance de pie y el alcance de punta. Estas diferencias están relacionadas con las necesidades de los distintos cargos en cuanto a las acciones que ejecutan. En conclusión, los parámetros morfológicos son componentes importantes del rendimiento en muchos deportes (voleibol). Las diferentes disciplinas deportivas requieren diferentes parámetros corporales y estructuras corporales para un rendimiento máximo.

Analysis of Knee Joint Stress During Drop Jump Landing in Females with Generalised Joint Hypermobility / 医用生物力学

Objective To analyze the differences of von Mises stress distribution in knee cartilage and meniscus in female with generalised joint hypermobility (GJH) and healthy female during drop jump landing. Methods The kinematic and ground reaction force (GRF) characteristics of knee joint in female with GJH and healthy female at the moment of peak vertical GRF (VGRF) during loading phase of drop jump landing were collected. The knee joint reaction force was calculated via inverse dynamics, and the combined force of knee joint along long axis of the femur was applied as the load. Based on three-dimensional (3D) finite element model of a female knee joint, numerical simulations were performed separately during drop jump landing of subjects in two groups, and von Mises stresses and stress distribution of knee cartilage and meniscus were calculated. Results At the moment of peak VGRF during drop jump landing, knee flexion and valgus angles in GJH group and control group showed a statistical significance (P<0. 05). Compared with control group, knee flexion angle decreased and valgus angle increased in GJH group. During drop jump landing, GJH group bore larger stress inside the knee joint, and stress distribution in weight-bearing areas of the medial and lateral tibiofemoral compartments was uneven, while the lateral femoral cartilage lateral condyle, the anterior and middle lateral of lateral tibial cartilage, the anterior angle and body lateral margin of lateral meniscus were stress concentration sites. Conclusions For females with GJH, the stability of knee joint decreases and force lines change in jumping events, due to the increased range of motion of knee joint and relaxation of joint capsule, which increases the risk of cartilage and meniscal injury in lateral knee joint. During jumping sports, females with GJH should especially prevent knee joint injury caused by altered force lines in frontal plane of knee joint.

Study on the Athletic Performance of Single Lower Extremity of High-level Male Athletes after Performing Drop Jump Tasks of Different Falling Heights / 中国运动医学杂志

Objective To explore the optimal falling height parameters for single-leg drop jump,so as toaddress the bilateral imbalance in the lower limbs of athletes and provide a reference for coaches to design training plans accurately and effectively.Methods Twelve first-grade male athletes were re-cruited for the study,including five track and field sprinters and seven basketball players(age:20.41±1.11 years,height:189.19±9.15 cm,weight:83.50±12.08 kg).The vertical jump platform was used to test the optimal counter-movement jump(CMJ)height for the dominant and non-dominant sides of the subject's lower extremities,and to determine the three falling heights of the low height(medium height minus 5 cm),medium height(50%of the optimal unilateral lower-limb CMJ height)and high height(medium height plus 5 cm).Six parameters of the drop jump performance,including buffer time,leg stiffness,peak vertical ground reaction force(vGRFpeak),the rate of force development(RFD),power,root mean square(RMS)of surface electromyogram signals were collected synchronous-ly using the Vicon Motion Capture System(200 Hz),Delsys portable wireless telemetry EMG test sys-tem and Kistler three-dimensional force platform(1000 Hz).Results(1)At the medium height,the av-erage buffer time,leg stiffness,vGRFpeak,RFD,RMS and power of either leg were significantly bet-ter than at the other two heights(P<0.05),and the leg stiffness of the non-dominant leg was signifi-cantly inferior to the dominant leg(P<0.05).(2)At the high height,the average buffer time,vGRFpeak and RMS of the dominant leg were significantly better than at low height(P<0.05),while the average buffer time,leg stiffness,vGRFpeak,RFD,power and RMS of the non-dominant legs were significant-ly worse than the dominant legs(P<0.05).Conclusion Coaches or athletes can choose the medium height(50%optimal unilateral lower-limb CMJ height)designed in this study and schedule unilateral lower limb drop jump training to optimize the athletic performance of the dominant or non-dominant legs to the greatest extent.However,as the falling height increases,the gap in athletic performance between the bilateral lower limbs tends to become more pronounced(especially at high height),thus the training should focus on strengthening the eccentric contraction ability and stability of the non-dom-inant side to avoid bilateral imbalance.

Symmetry of Single Leg Vertical Jump Height Hides Abnormal Lower Limb Biomechanics in Athletes after Anterior Cruciate Ligament Reconstruction / 中国运动医学杂志

Objective To explore whether the single leg vertical jump height limb symmetry index(LSI)＞90%can represent the normal lower limb biomechanics in athletes after anterior cruciate liga-ment reconstruction(ACLR)during jumping.Methods Forty-six athletes after ACLR were divided into a low symmetry group(jump height LSI＜90%,n=23)and a high symmetry group(jump height LSI＞90%,n=23)according to the symmetry of single leg vertical jump height,while 24 healthy counter-part athletes were chosen into the control group.The kinematic and kinetic characteristics were com-pared among the three groups.Results(1)At the take-off stage,compared with the control group,both sides of the low-symmetry group had higher peak hip flexion angle(P＜0.05),but only the operat-ed side showed lower knee flexion moment(P=0.002),knee power(P=0.01),ankle power(P=0.045)and peak vertical ground reaction force(P=0.008).(2)At the take-off stage,there were no significant differences between the operated side of the high symmetry group and the control group in all measure-ments.However,compared with the healthy side,the operated side demonstrated lower knee flexion moment(P=0.001),knee power(P=0.002),total power of lower limb(P=0.001)and peak vertical ground reaction force(P=0.046).(3)During landing,compared with the control group,bilateral sides of the low symmetry group showed a higher peak hip flexion angle(P＜0.05)and a lower peak flexion knee angle(P＜0.05),but its operated side demonstrated lower peak ankle dorsiflexion angle(P=0.018),knee flexion moment(P=0.005),knee power(P=0.037),ankle power(P=0.002),total power of lower limb(P=0.042),and peak vertical ground reaction force(P=0.022).(4)During landing,there were no significant differences in all variables between the operated side of the high symmetry group and the control group.However,compared with its healthy side,the affected side of the high symmetry group demonstrated lower knee flexion moment(P=0.002),ankle dorsiflexion moment(P=0.003),knee power(P＜0.001),total power of lower limbs(P=0.001),and peak vertical ground reaction force(P=0.023).Conclusion Despite achieving the single leg vertical jump height LSI＞90%,athletes after ACLR still showed abnormal lower limb biomechanical characteristics during propulsion and landing.In addition,such abnormality is more obvious in athletes after ACLR with jump height LSI＜90%.Therefore,sym-metry in jump height does not represent normal lower extremity biomechanics in athletes after ACLR.

Relationship of speed and unilateral vertical jump performance of basketball athletes / Relação entre a velocidade e desempenho de salto vertical unilateral de atletas de basquetebol

Abstract Basketball is a sport practiced around the world in this way, performances tests especially with low-cost and accessible are suggested to adjust the training. The 00aim of present study was to evaluate and correlate the speed and jump performance of lower limbs of basketball athletes from the Praia Grande, city of São Paulo, Brazil. Twelve male athletes (6.92 ± 2.57 years of pratice) from the Basketball team of Praia Grande City, aged 18.7 ± 0.6 years, height 1.85 ± 0.06, body mass 83.66 ± 10.16 kg were evaluated. The athletes were submitted to test sessions using the protocol for evaluating the maximum speed of 20 meters and the unilateral vertical jump. The speed on 20 meter test was 3.53 ± 0.20 seconds. Although an asymmetry of 17.81 ± 14.64% was found, no statistical difference (p = 0.817) was found between the dominant (36.50 ± 7.36 cm) and non-dominant (35.92 ± 5.63 cm) of vertical jump performance. Additionally, correlation between 20-meter test and values jump was found to dominant leg (p = 0.042) but not to non-dominant leg (p = 0.704). In conclusion, although asymmetry was found between members of the dominant and non-dominant side of the pitch, did not show any difference in the vertical jump.

Resumo O basquete é um esporte praticado em todo o mundo, desta forma, testes de desempenho principalmente com baixo custo e acessíveis são sugeridos para adequar o treinamento. O objetivo do presente estudo foi avaliar e correlacionar a velocidade e o desempenho de salto de membros inferiores de atletas de basquetebol da cidade da Praia Grande, São Paulo, Brasil. Foram avaliados 12 atletas do sexo masculino (6,92 ± 2,57 anos de prática) da equipe de Basquetebol da Cidade de Praia Grande, com idade 18,7 ± 0,6 anos, estatura 1,85 ± 0,06, massa corporal 83,66 ± 10,16 kg. Os atletas foram submetidos a sessões de testes utilizando o protocolo de avaliação da velocidade máxima de 20 metros e do salto vertical unilateral. A velocidade no teste de 20 metros foi de 3,53 ± 0,20 segundos. Embora tenha sido encontrada uma assimetria de 17,81 ± 14,64%, não foi encontrada diferença estatística (p = 0,817) entre o desempenho do salto vertical dominante (36,50 ± 7,36 cm) e não dominante (35,92 ± 5,63 cm). Além disso, foi encontrada correlação entre o teste de 20 metros e os valores de salto para perna dominante (p = 0,042), mas não para perna não dominante (p = 0,704). Em conclusão, embora tenha sido encontrada assimetria entre membros do lado dominante e não dominante do campo, não houve diferença no salto vertical

Effect of land- and aquatic-based plyometrics on spike and block reaches in young volleyball players: a pilot study

Abstract Aim: The purpose of this pilot study was to analyze the feasibility of the intervention and measures of a six-week land- and aquatic-based plyometric training on spike and block reaches in young volleyball athletes. Methods: Twelve female players were divided into a land group (LG) (n = 6, 12.4 ± 0.3 years, 1.61 ± 0.04 m, 57.0 ± 9.3 kg) and a water group (WG) (n = 6, 12.5 ± 0.5 years, 1.57 ± 0.06 m, 48.9 ± 8.5 kg). The spike and block (without step, with slide step, and with crossover step) reach and countermovement jump height were evaluated before and after a 6-week plyometric training protocol. Duration (total and of each session), adhesion and adherence, and safeness of the intervention; completion of assessments, within-trial reliability, and variability of the outcome measures and preliminary results were the variables of interest. To analyze the effect of the training on jump performance, the Wilcoxon test was used (p < 0.05), and effect sizes (r) were calculated. Results: All participants concluded the intervention and the assessments as planned. No dropouts or adverse events were registered during the study. The within-trial reliability for all assessment tests was considered excellent (ICC ≥ 0.9). Preliminary results indicate that LG improved the reach of the spike and block with the slide step; and that WG improved the spike, block with the slide step to the left, and block without movement reaches (p < 0.05; large effect size). Conclusion: An intervention of six weeks of plyometric training on land and in water is feasible, and preliminary results indicate that both training protocols may benefit the performance of spike and block in young volleyball athletes.

Comparative Effects of Dynamic Stretching and Ice Bag Application On the Physical Performance in Recreational Basketball Players: A Randomized Crossover Study

Introduction: Researchers found that cryotherapy at the ankle joint heightened adjacent muscle activity and reflex amplitude, which facilitated greater force production at the ankle complex. Furthermore, cryotherapy appears to increase musculoarticular stiffness, which has been associated with heightened muscular performance at a joint. Aim and objective: the aim of the study is to examine the influence of dynamic stretching and IBA technique on the physical performance. Methodology: Total 20 healthy male basketball athletes encompassing two groups participated in the current study. The study consisted of two groups, Group A (ice bag application) and Group B (dynamic stretching). Cold compress was applied over the anterior thigh, posterior thigh, and calf. Subjects were assigned to Group A, and Group B, using Convenience sampling method. Each candidate performed the 5 minutes of jogging before taking intervention. All subjects performed three functional performance tests: Vertical Jump Test, Agility T-test & 20-meter sprint. Each participant attended an orientation session to become familiar with the testing procedures. Subjects were randomly assigned into two groups and exposed to a crossover study design. The experiment was performed on two separate occasions whereby one group received the dynamic stretching in the first session, while the other group uses the cryotherapy first. After 48 hours, (cooling session) on the next occasion, the groups were changed and the second group receives the cryotherapy, while the first group performs dynamic stretching. On both occasions, the dynamic stretching and cryotherapy interventions were the same. Between the sessions, the subjects will not allow to participate in any kind of vigorous physical activity. Results: The present study showed an increase in performance of recreational Basketball players by the combination of 5 minutes of warm up plus 6 min of dynamic stretching on the vertical jump height and 20-meter sprint

Comparación de pruebas de potencia de miembros inferiores por dos métodos indirectos en voleibolistas categoría sub-18 / Comparação dos testes de potência dos membros inferiores por dois métodos indiretos em jogadores de voleibol U18 / Comparison of lower limb power tests by two indirect methods in volleyball players under-18 category

RESUMEN El test de salto vertical es muy interesante como prueba física, en el voleibol moderno, para valorar la potencia de piernas, ya que de esa manera el preparador físico puede planificar un programa de fuerza-velocidad con la intención de mejorar sus prestaciones físicas en el terreno de juego. El voleibol es un deporte que se caracteriza por acciones de juego de corta duración y de gran intensidad, alternadas por cortos períodos de descanso. Esto hace pensar en la necesidad de desarrollar en las voleibolistas una gran potencia, fundamentalmente en los miembros inferiores, aspectos que fue evaluado a diez atletas de voleibol categoría sub-18 de la Escuela Nacional de voleibol por métodos indirectos Lewis y Harman, a las que se les realizó un estudio transversal en la etapa de preparación física general. Este trabajo tuvo como objetivo comparar los niveles de potencia de miembros inferiores por ambos test en un periodo de seis semanas. Como métodos empíricos se utilizaron la medición y los test indirectos para evaluar la potencia de salto. Se obtienen resultados satisfactorios en ambos test, fundamentalmente después de someter a las atletas a un sistema de ejercicios que se muestran con mayor nivel de información para el entrenador los valores de la potencia de Harman, ya que en este tiene en cuenta la acción de la aceleración gravitatoria que debe vencer en la fase de despegue. A partir de los resultados, se brindaron sugerencias individuales para el entrenamiento de dichos atletas.

RESUMO O teste de salto vertical é muito interessante como teste físico, no voleibol moderno, para avaliar a potência das pernas, uma vez que desta forma o treinador físico pode planear um programa de força-velocidade com a intenção de melhorar o desempenho físico no campo de jogo. O voleibol é um desporto caracterizado por ações de jogo curtas e de alta intensidade, alternando com curtos períodos de descanso. Isto sugere a necessidade de os jogadores de voleibol desenvolverem grande poder, fundamentalmente nos membros inferiores, aspectos que foram avaliados em dez atletas de voleibol da categoria U-18 da National Volleyball School, utilizando métodos indiretos de Lewis e Harman, que foram submetidos a um estudo transversal durante a fase geral de preparação física. O objectivo deste estudo era comparar os níveis de potência dos membros inferiores por ambos os testes ao longo de um período de seis semanas. Os métodos empíricos utilizados foram a medição e testes indiretos para avaliar a potência de salto. Foram obtidos resultados satisfatórios em ambos os testes, fundamentalmente depois de submeter os atletas a um sistema de exercícios que mostrou com um maior nível de informação para o treinador os valores da potência de Harman, uma vez que tem em conta a ação da aceleração gravitacional que deve ser superada na fase de descolagem. A partir dos resultados, foram fornecidas sugestões individuais para o treino destes atletas

ABSTRACT The vertical jump test is very interesting as a test physical in modern volleyball to assess the power of the legs, since in this way the physical trainer can plan a strength-speed program with the intention of improving their physical performance on the game field. Volleyball is a sport that is characterized by short duration and high intensity game actions, alternated by short periods of rest. This suggests the need to develop great power in volleyball female players, fundamentally in the lower limbs, aspects that were evaluated on ten volleyball athletes in the sub-18 category of the National Volleyball School by indirect methods Lewis and Harman, to whom a cross-sectional study was carried out in the stage of general physical preparation. The objective of this work was to compare the power levels of the lower limbs by both tests in a period of six weeks. As empirical methods, measurement and indirect tests were used to evaluate jumping power. Satisfactory results are obtained in both tests, fundamentally after subjecting the athletes to a system of exercises that show the Harman power values with a higher level of information for the coach, since in this it takes into account the action of the gravitational acceleration that must be overcome in the take-off phase. Based on the results, individual suggestions for the training of these athletes were provided.

Relationship between body composition, multiple repeated sprint ability and vertical jump performance in elite badminton players / Relación entre la composición corporal, la capacidad de realizar múltiples sprints repetidos y el rendimiento del salto vertical en jugadores de bádminton de élite

SUMMARY: The purpose of this study was to assess the correlation between the body composition, multiple repeated sprint ability (MRSAB) test, and vertical jump performance. Fifteen voluntary elite Turkish badminton players participated in the study. The MRSAB test consisted of 2 repetitions of 4 movements (4x3m) separated by 30 seconds of passive recovery. The best time (BT), meantime (MT), total time (TT), and fatigue index (FI) were measured. Body composition was evaluated through dual-energy X-ray absorptiometry (DEXA). Squat jump (SJ) test for explosive power and countermovement jump (CMJ) test for elastic power were used. The main findings were that there was a significant correlation between MRSAB MT and TT with lean body mass, lean arm mass, and trunk lean mass (kg) of male badminton players. However, no significant correlation was observed among MRSAB MT, BT, and TT with another total/regional body composition of female badminton players (p>0.05). Moreover, the results of male badminton players showed that there was a significant negative correlation between FI and percentage ofbody fat (%BF), percentage of leg fat (%LF), percentage of trunk fat (%TF), and trunk mass. In addition, there was a significant negative correlation between FI with %BF, body fat mass kg, percentage of arm fat (%AF), arm fat mass, and %LF of female badminton players. It was also found in the study that there was a significant correlation between SJ and %LF; CMJ and %BF, body fat mass kg, %AF, %LF and leg fat mass kg. However, no significant correlation was observed among CMJ and SJ with other total/regional body compositions of male badminton players (p>0,05). Finally, changes in body composition are important issues for the physical performance level of badminton players as regional excess body fat may cause deterioration, especially in repeated-sprint ability and jumping performance.

RESUMEN: El propósito de este estudio fue evaluar la correlación entre la composición corporal, la prueba de capacidad de sprint repetido (MRSAB) y el rendimiento del salto vertical. Quince jugadores voluntarios de bádminton turcos de élite participaron en el estudio. El test MRSAB consistió en 2 repeticiones de 4 movimientos (4x3m) separados por 30 segundos de recuperación pasiva. Se midieron el mejor tiempo (BT), el tiempo medio (MT), el tiempo total (TT) y el índice de fatiga (FI). La composición corporal se evaluó mediante absorciometría de rayos X de energía dual (DEXA). Se utilizó la prueba de salto desde la sentadilla (SJ) para la potencia explosiva y la prueba de salto con contramovimiento (CMJ) para la potencia elástica. Los principales hallazgos fueron una correlación significativa entre MRSAB MT y TT con la masa corporal magra, la masa magra del brazo y la masa magra del tronco (kg) de los jugadores de bádminton hombres. Sin embargo, no se observó una correlación significativa entre MRSAB MT, BT y TT con otra composición corporal total/regional de jugadoras de bádminton (p>0,05). Además, los resultados de los jugadores hombres de bádminton mostraron que había una correlación negativa significativa entre FI y el porcentaje de grasa corporal (% BF), porcentaje de grasa en las piernas (% LF), porcentaje de grasa en el tronco (% TF) y masa del tronco. Además, hubo una correlación negativa significativa entre FI con %GC, masa de grasa corporal en kg, porcentaje de grasa en el brazo (%AF), masa de grasa en el brazo y %LF de las jugadoras de bádminton. También se descubrió en el estudio que había una correlación significativa entre SJ y %LF; CMJ y %BF, masa grasa corporal kg, %AF, %LF y masa grasa de piernas kg. Sin embargo, no se observó una correlación significativa entre CMJ y SJ con otras composiciones corporales totales/regionales de los hombres jugadores de bádminton (p>0,05). Finalmente, los cambios en la composición corporal son cuestiones importantes para el nivel de rendimiento físico de los jugadores de bádminton, debido a que el exceso de grasa corporal regional, puede causar un deterioro, especialmente en la capacidad de repetir sprints y en el rendimiento de los saltos.

Relationship between physical fitness and phase angle based on bioelectrical impedance analysis in 6-year-old children / 体力科学

Phase angle, calculated as the arc-tangent of the reactance-to-resistance ratio in bioelectrical impedance analysis, represents skeletal muscle quality, and is suggested to be an indicator of sports ability and physical fitness. However, it is unclear whether phase angle is related to physical fitness in early childhood in Japanese subjects. The purpose of this study was to examine the cross-sectional relationship between physical fitness and bioelectrical impedance analysis-based phase angle in 6-year-old Japanese children. The subjects were 85 kindergarten students who participated in a physical fitness test and body composition assessment in 2017, 2018 or 2019, in the third year of kindergarten. Fitness tests included grip strength, standing long jump, and 25 m run. A multi-frequency composition analyzer was used for body composition analysis, and the phase angle of the left half of the body was acquired at 50 kHz. Statistical analysis was performed using a general linear model to calculate the regression coefficient of phase angle for physical fitness. Phase angle correlated significantly with the standing long jump and 25 m run. The regression coefficient (±standard error) of phase angle in the standing long jump in the fully adjusted model was 5.098 ±2.264 (p<0.05), and that in the 25 m run was -0.179 ±0.088 (p<0.05). There was no significant correlation between phase angle and grip strength. These results suggest that phase angle based on bioelectrical impedance analysis might be related to lower limb muscle function and running ability in 6-year-old Japanese children.

Potencia muscular en relación a la composición corporal en jugadores de voleibol adolescentes según género / Muscle power in relation to body compositionin adolescent volleyball players according to gender

RESUMEN Objetivo: analizar si existe diferencia en la composición corporal por género y si esta influye sobre el rendimiento físico de jugadores de vóleibol adolecentes. Método: se agruparon veinticinco jugadores de vóleibol (Hombres n = 10, Mujeres n = 15). Se midió la composición corporal y potencia muscular mediante la prueba de salto en contra movimiento y remate de balón. Resultados: se observó que los hombres presentaban una mayor masa muscular junto a una menor grasa corporal relacionada a un mayor rendimiento en las pruebas de rendimiento físico. Conclusión: los hombres presentan una mayor masa muscular y menor grasa corporal junto a un mejor rendimiento en las pruebas de potencia muscular.

ABSTRACT Objective: analyze if there is a difference in body composition by gender and if this influences the physical performance of adolescent volleyball players. Method: twenty-five adolescent volleyball players (Men n = 10, Women n = 15) were grouped together. Body composition and muscle power were measured using the countermovement jump test and volleyball spike. Results: the observations were that men had greater muscle mass together with lower body fat related to higher performance in physical performance tests. Conclusion: men have greater muscle mass and lower body fat along with better performance in muscle power tests.

Relación entre las características antropométricas de masa muscular de extremidad inferior y la potencia de salto de jóvenes deportistas / Relation Between Anthropometric Muscle Mass Characteristics of Lower Limbs and Jump Power in Young Athletes

Resumen La antropometría regional resulta ser un procedimiento importante en la proyección del desempeño de un deportista. El objetivo del presente estudio es relacionar las características antropométricas de extremidad inferior con la potencia de salto en jóvenes deportistas. Se utilizó una metodología correlacional donde se evaluaron a 44 deportistas juveniles (30 hombres y 14 mujeres), a los cuales, se les midió la altura del salto en sentadilla de 90° (SJ), contra movimiento con manos fijas (CMJ-MF) y contra movimiento con manos libres (CMJ-ML). Estas variables derivaron al cálculo de potencia. Junto con esto se determinó características antropométricas de miembro inferior vinculados a pliegues cutáneos y perímetros, obteniendo valores de muslo medio (MMED) y máximo (MMAX), perímetro corregido de pantorrilla (PCP), área de sección muscular de cuádriceps (ASMC), área de sección muscular de isquiotibial (ASMI) y área de sección muscular total de muslo (ASMM). Los resultados mostraron una correlación significativa entre el perímetro corregido de pantorrilla y la potencia de salto en SJ (r=0,73; p=0,00), CMJ-MF (r=0,72; p=0,00) y CMJ-ML (r=0,7; p=0,00). En conclusión, el perímetro de pantorrilla presentó componentes relacionados a la potencia de salto de los deportistas juveniles.

Abstract Regional anthropometry turns out to be an important procedure in the projection of the athlete's performance. The objective of the present study is to relate the anthropometric characteristics of the lower limbs of the body with the jumping power of young athletes. A correlational methodology was used to evaluate 44 youth athletes (30 men and 14 women). They were measured for jump height in 90° squat (SJ), countermovement with fixed hands (CMJ-MF), and countermovement with free hands (CMJ-ML). These variables derived into the power calculation. With this, we established the anthropometric characteristic of lower body parts linked to skinfolds and perimeters, obtaining values of mid (MMED) and maximum thigh (MMAX), corrected calf perimeter (PCP), quadriceps muscle section area (ASMC), hamstring muscular section area (ASMI), and total section of the muscular thigh area (ASMM). The results showed a significant correlation between the corrected calf perimeter and the jump power in SJ (r=0.73; p=0.00), CMJ-MF (r=0.72; p=0.00) and CMJ-ML(r=0.7; p=0.00). In conclusion, the calf perimeter presented related components to the young athletes' jumping power.

Resumo A antropometria regional acaba sendo um procedimento importante na projeção do desempenho de um atleta. O objetivo do presente estudo é relacionar as características antropométricas do membro inferior com a força de salto em jovens atletas. Foi utilizada uma metodologia correlacional onde foram avaliados 44 atletas jovens (30 homens e 14 mulheres), para os quais foi medida a altura do salto no agachamento a 90 ° (SJ), contra movimento com mãos fixas (CMJ-MF) e movimento contrário livre (CMJ-ML). Essas variáveis levaram ao cálculo da potência. Paralelamente, foram determinadas as características antropométricas do membro inferior relacionadas às dobras cutâneas e perímetros, obtendo-se os valores da coxa média (MMED) e máxima (MMAX), perímetro corrigido da panturrilha (PCP), área de seção muscular do quadríceps (ASMC), área da seção do músculo isquiotibial (ASMI) e área total da seção do músculo da coxa (ASMM). Os resultados mostraram uma correlação significativa entre a circunferência da panturrilha corrigida e a força de salto em SJ (r= 0,73; p = 0,00), CMJ-MF (r= 0,72; p = 0,00) e CMJ-ML (r= 0,7; p = 0,00) Em conclusão, a circunferência da panturrilha apresentou componentes relacionados à força de salto dos jovens atletas.

Vínculo entre composición corporal, sprint y salto vertical en futbolistas jóvenes de élite de Chile / Link Between Body Composition, Sprint and Vertical Jump in Young Elite Soccer Players from Chile

Resumen El objetivo de este trabajo fue conocer las relaciones entre indicadores de composición corporal y rendimiento físico en jugadores jóvenes de élite y determinar si existen diferencias entre posiciones de juego y series. La muestra fue de futbolistas seleccionados Sub-15 (n=24) y Sub-17 (n=20) varones, divididos por posición de juego. Se evaluaron indicadores composición corporal, porcentaje de masa grasa (%MG) y porcentaje de masa muscular (%MM). Se evaluaron salto desde sentadilla (SJ), salto con contramovimiento (CMJ), velocidad lineal en 10 (T10) y 30 metros (T30). Se relacionaron variables de composición corporal y rendimiento físico, y se buscaron diferencias entre posiciones de juego y entre categorías. Se hallaron grandes asociaciones significativas en la categoría Sub-15 entre %MM con SJ y CMJ, y moderadas entre %MG con T10, SJ y CMJ. En Sub-17 una asociación significativa grande entre %MM y T30, y entre %MG y T30. Se hallaron diferencias significativas en %MG en la categoría Sub-17, entre los arqueros vs defensas y delanteros. Se encontraron diferencias significativas moderadas en %MM entre categorías y diferencias muy grandes en T10 y T30, y una diferencia moderada en SJ. Es posible concluir que la composición corporal %MM y %MG se relaciona con el rendimiento físico. Además, existen diferencias en %MG entre los arqueros vs los jugadores de campo y diferencias en las variables de composición corporal y rendimiento físico entre jugadores Sub-17 y sub-15. Los resultados obtenidos pueden servir de referencia o de parámetros de comparación de jugadores jóvenes a nivel nacional en la detección de talentos.

Abstract The study aimed to know the relationships between indicators of body composition and physical performance in elite young players and determine if there are differences between playing positions and series. The sample was of selected U-15 (n=24) and U-17 (n=20) male players, divided by playing position. Body composition, fat mass percentage (%MG), and muscle mass percentage (%MM) indicators were evaluated. Also, Squat Jump (SJ), Countermovement Jump (CMJ), linear velocity in 10 (T10) and 30 meters (T30) were evaluated. Body composition and physical performance variables were related, and differences between playing positions and between categories were sought. Significant large associations were found in the U-15 category between %MM with SJ and CMJ and moderate associations between %MG with T10, SJ, and CMJ. In the U-17 category, a significant large association was found between %MM and T30 and between %MG and T30. Significant differences in %MG were found in the U-17 category between goalkeepers vs. defenders and forwards. Moderate significant differences were found in %MM between categories and very large differences in T10 and T30, and a moderate difference in SJ. Therefore, it is possible to conclude that the body composition %MM and %MG is related to physical performance. In addition, there are differences in %MG between goalkeepers vs. outfield players and differences in body composition and physical performance variables between U-17 and U-15 players. The results obtained can be used as a reference or as parameters for comparing young players at the national level in the detection of talent.

Resumo O objetivo deste trabalho foi conhecer as relações entre indicadores de composição corporal e desempenho físico em jovens jogadores de elite e verificar se existem diferenças entre posições de jogo e séries. A amostra foi composta por jogadores de futebol masculino sub-15 (n = 24) e sub-17 (n = 20) selecionados, divididos por posição de jogo. Foram avaliados indicadores de composição corporal, percentual de massa gorda (% MG) e percentual de massa muscular (% MM). Foram avaliados o salto de agachamento (SJ), salto de contra movimento (CMJ), velocidade linear a 10 (T10) e 30 metros (T30). Variáveis de composição corporal e desempenho físico foram relacionadas, e diferenças entre as posições de jogo e entre as categorias foram pesquisadas. Grandes associações significativas foram encontradas na categoria de menores de 15 anos entre% MM com SJ e CMJ, e moderadas entre% MG com T10, SJ e CMJ. Em Sub-17, uma grande associação significativa entre% MM e T30 e entre% MG e T30. Diferenças significativas foram encontradas na % MG na categoria Sub-17, entre goleiros x zagueiros e atacantes. Diferenças moderadas significativas foram encontradas em % MM entre as categorias e diferenças muito grandes em T10 e T30, e uma diferença moderada em SJ. É possível concluir que a composição corporal % MM e% MG está relacionada ao desempenho físico. Além disso, há diferenças na % MG entre goleiros e jogadores de campo e diferenças nas variáveis de composição corporal e desempenho físico entre jogadores Sub-17 e Sub-15. Os resultados obtidos podem servir de referência ou parâmetro de comparação de jovens jogadores a nível nacional para a detecção de talentos.

Análisis del salto vertical de voleibolistas de primera categoría / Análise do salto vertical de jogadores de Voleibol de primeira classe / Analysis of vertical jump of first category volley ball players

RESUMEN La saltabilidad en el voleibol está estrechamente vinculada con la capacidad de fuerza-velocidad que deben poseer los jugadores para realizar una amplia cantidad de saltos durante un partido. De ahí que sean diversas las interrogantes de los entrenadores para conseguir que sus atletas lleguen a lo más alto de la élite. El objetivo del estudio que se presenta versa en analizar los indicadores que influyen en el salto vertical con contramovimiento para el perfeccionamiento de la preparación física en jugadores de voleibol primera categoría de La Habana, para poder dar tratamiento desde la sesión de entrenamiento. Para la adquisición de los datos, se utilizaron métodos científicos tales como la observación, la medición con una plataforma de fuerza de origen alemán y el software TEMPLO con su respectivo modelo Performance Análisis y una entrevista a los entrenadores del equipo. En este mismo orden, a los datos obtenidos se les aplicó la estadística descriptiva y los resultados se presentan a través de gráficos y tablas, donde se muestran las deficiencias en cuanto a la capacidad de salto para estos jugadores, evidenciándose la impericia en la transferencia de la fase excéntrica a la concéntrica y su resultado en el éxito del juego.

RESUMO A capacidade de salto no Voleibol está intimamente ligada à capacidade de força-velocidade que os jogadores devem possuir para executar um grande número de saltos durante uma partida. Assim, há várias perguntas que os treinadores têm de fazer a si próprios para garantir que os seus atletas cheguem ao topo da elite. O propósito do estudo aqui apresentado é analisar os indicadores que influenciam o salto vertical com contra movimento para a melhoria da preparação física dos jogadores de Voleibol de primeira categoria em Havana, a fim de poder proporcionar o tratamento a partir da sessão de treino. Para a aquisição dos dados, foram utilizados métodos científicos como a observação, medição com uma plataforma de força alemã e o software TEMPLO com o seu respectivo modelo de análise de desempenho e uma entrevista com os treinadores da equipa. Nesta mesma ordem, foram aplicadas estatísticas descritivas aos dados obtidos e os resultados são apresentados através de gráficos e tabelas, que mostram as deficiências em termos de capacidade de salto para estes jogadores, evidenciando a falta de habilidade na transferência da fase excêntrica para a fase concêntrica e o seu resultado no sucesso do jogo.

ABSTRACT The jumping capacity in volleyball is closely linked to the force-speed capacity that players must possess to perform a wide number of jumps during a match. Hence, there are several questions of coaches to get their athletes to reach the top of the elite. The objective of the study presented is to analyze the indicators that influence the vertical jump with countermovement, for the improvement of physical preparation in volleyball player's first category of Havana, to be able to give treatment from the training session. For the acquisition of the data, a strength platform of German origin and the TEMPLO software with its respective Performance Analysis model were used. In this same order, descriptive statistics was applied to the data obtained, and the results are presented through graphs and tables, where the deficiencies in terms of jumping capacity for these players are shown, evidencing the lack of expertise in the transfer from the eccentric phase to the concentric and its result in the success of the game.