Spatiotemporal variables comparison between drop jump and horizontal drop jump in elite jumpers and sprinters.

Background: General expectations speculated that there are differences between drop jump (DJ) and horizontal drop jump (HDJ) exercises. While these criteria may be valid, we have yet to find a report that explores these differences in competitive level athletes. Objective: The study aimed to compare spatiotemporal variables in the drop jump (DJ) vs. the horizontal drop jump (HDJ) in elite jumpers and sprinters. Methods: Sixteen international-level male athletes performed two DJ attempts at different fall heights 0.3, 0.4, and 0.5 m (DJ30, DJ40, and DJ50), and after 2 h, they performed two HDJ attempts (HDJ30, HDJ40, HDJ50). All jumps were performed on a Kistler force plate. The variables analyzed were ground contact time (GCT), flight time (FT), eccentric phase time, concentric phase time, and time to peak concentric force. Results: The GCT was found to be significantly shorter in DJ vs. HDJ (Z = 4.980; p = 0.0001; ES = 3.11). FT was significantly lower in DJ30 versus HDJ30 (Z = 4.845; p = 0.0001, d = 3.79), but significantly higher in DJ40 vs. HDJ40 (Z = 4.437; p ≤ 0.0001, d = 3.70) and in DJ50 vs. HDJ50 (Z = 4.549; p ≤ 0.0001, d = 4.72). Conclusions: It is concluded that the HDJ requires more time for force production, that the eccentric component requires more time than the concentric and that it is not recommended to use the HDJ over the DJ for reactive purposes. This is the first study that comprehensively compare the differences between DJ and HDJ, which will assist coaches and researchers in the design of future training strategies.

Validity and Reliability of a Load Cell Sensor-Based Device for Assessment of the Isometric Mid-Thigh Pull Test.

In recent years, there has been an exponential increase in the number of devices developed to measure or estimate physical exercise. However, before these devices can be used in a practical and research environment, it is necessary to determine their validity and reliability. The purpose of this study is to test the validity and reliability of a load cell sensor-based device (LC) for measuring the peak force (PFr) and the rate of force development (RFD) during the isometric mid-thigh pull (IMTP) test, using a force plate (FP) as the gold standard. Forty-two undergraduate sport science students (male and female) participated in this study. In a single session, they performed three repetitions of the IMTP test, being tested simultaneously with an LC device and a Kistler force platform (FP). The PFr and RFD data were obtained from the force-time curve of the FP and compared with the LC data, provided automatically by the software of the device (Smart Traction device©). The mean difference between the results obtained by the LC device and the gold-standard equipment (FP) was not significantly different (p > 0.05), for both PFr and RFD, which suggests the validity of the ST results. Bland-Altman analysis showed a small mean difference in PFr = 1.69 N, upper bound = 47.88 N, and lower bound = -51.27 N. RFD showed that the mean difference was -5.27 N/s, upper limit = 44.36 N/s, and lower limit = -54.91 N/s. Our results suggest that the LC device can be used in the assessment of the isometric-mid-thigh-pull test as a valid and reliable tool. It is recommended that this device's users consider these research results before putting the ST into clinical practice.

Methodological considerations for determining the volume and intensity of drop jump training. A systematic, critical and prepositive review.

This systematic review provides critical and propositional information on criteria for determining the volume and intensity of drop jumps during plyometric training programs. Eligibility criteria were defined according to PICOS: Participants: male or female athletes, trained or recreationally active (16-40 years). Intervention duration: more than 4 weeks. COMPARATORS: passive or active control group during a plyometric training program. OUTCOMES: information on improvement with Drop Jump or Depth Jump, with other jumps, acceleration, sprint, strength, and power output. DESIGN: randomized controlled trials. We searched articles published in PubMed, SPORTDiscus, Web of Science, and Scopus. The search was conducted until 10 September 2022 for English-language articles only. The risk of bias was assessed using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) for randomized controlled studies. We identified 31495 studies, of which only 22 were included. We found that six groups presented results with women, 15 presented results with men, and the remaining four presented mixed studies. Of the 686 people recruited, 329 participants aged 25.79 ± 4.76 years were involved in training. Methodological problems in training intensity, volume distribution, and individualization were noted, but methodological recommendations for their solution are also provided. It is concluded that the drop height should not be understood as the intensity determinant of plyometric training. Intensity is determined by ground reaction forces, power output, and jump height, among other factors. Furthermore, the athletes' experience level selection should be based on the formulas recommended within this research. These results could be helpful for those who intend to conduct new plyometric training programs and research.

Validity and reliability of the Output sport device for assessing drop jump performance.

The devices for measuring plyometric exercise in field conditions are becoming increasingly prevalent in applied research and practice. However, before the use of a device in an applied setting, the validity and reliability of such an instrument must be determined. The study aimed to assess the validity and reliability of the Output Sport, an inertial measurement unit (IMU), through comparisons with a force plate for research purposes. A repeated measure test-retest study was performed. Reliability was assessed during single-session trials (i.e., intrasession reliability). A total of 34 national/university level athletes (13 females, 21 males) performed three drop jumps with a fall from 30 cm while both devices recorded ground contact time (GCT), flight time (FT), jump height (HJ), and reactive strength index (RSI). T-tests demonstrated that data collected from the IMU device were significantly different to the force platform for all reported variables (all p < 0.01). The intraclass correlation coefficients (ICC) demonstrated good-to-excellent reliability, but with a large range of confidence intervals (CI 95%) for GCT (0.825, 0.291-0.930), FT (0.928, 0.756-0.958), HJ (0.921, 0.773-0.964), and RSI (0.772, 0.151-0.907). The Bland-Altman test showed that the device overestimated contact times and underestimated the other variables. Upon landing, greater ground contact times (i.e., ≥0.355ms) were associated with higher reliability. These results suggest that a single IMU can be used to track changes somewhat accurately and reliably in jump metrics, especially when the GCT is greater than 0.355ms. It is recommended that before practitioners and trainers use the device as a cost-effective solution in the field, further research should be carried out to evaluate a range of data on the type of exercise to be performed.

The Validity of the Push Band 2.0 on the Reactive Strength Index Assessment in Drop Jump.

This study aims to verify the validity of the Push Band 2.0 (PB2.0) device on the reactive strength index (RSI) measurement, using a force plate (FP) and an optical sensor device, OptoJump (OPT), as a reference. Twenty trained athletes performed 60 drop jump trials with a height box of 30 cm. A randomized repeated measures study was conducted during a single session using the PB2.0, the OPT, and the plate force manually synchronized to obtain RSI data for each jump. Validity was analyzed by contrasting three measures: the intra-class correlation coefficient (ICC), the Bland-Altman test, and R2 coefficient of determination. Bland-Altman analysis showed that RSI and FP for PB2.0 (media = -0.047; IC 93.34%) of all data were within the confidence interval, indicating a statistically reliable result. The RSI measured by the OPT and PB2.0 also provided similar values (media = -0.047). These data are identical to other validity measures (ICC and linear correlation) but differ in the R2 values. The explained variation of PB2.0 measures attained only 29.3% of the FP (R2 = 0.293) and 29.5% (R2 = 0.295) of the OPT assessment, showing a very low determination coefficient. The results of this study point to caution in the use of PB2.0 when measuring RSI in scientific research.

Análisis integral de la motivación en boxeadores / Comprehensive analysis of boxers' motivation

Introducción: La motivación permite la permanencia del deportista en el proceso que participa, es un componente indispensable en el logro de altos rendimientos deportivos y es parte indispensable de la preparación psicológica. Objetivo: Diagnosticar la motivación en boxeadores a través de indicadores de la preparación psicológica. Métodos: El estudio se realizó con el equipo provincial de boxeo de Guantánamo, primera categoría (población estudiada: 16 sujetos). Se utilizaron métodos del nivel teórico, técnicas abiertas y la observación sistemática a la actividad deportiva. Se determinaron parámetros que diagnostican la motivación, incluyendo la técnica de los 10 deseos, de composición y completamiento de frases, así como una entrevista y observación durante tres semanas. Resultados: Los principales resultados aportaron la determinación de los componentes: cognitivo, afectivo y conativo de la motivación hacia el deporte y sus respectivos indicadores. Conclusiones: En el equipo de boxeo, los motivos deportivos no regulan efectivamente la personalidad en pos de alcanzar los mejores rendimientos en la actividad deportiva (AU)

Introduction: Motivation leads to the permanence of sportspeople in the management process where they are involved. It is an indispensable factor in the achievement of high sport results, and a crucial part of psychological preparation. Objective: Diagnose boxers' motivation using indicators enabling its characterization. Methods: A study was conducted of Guantánamo provincial boxing team, first category (study population: 16 subjects), based on theoretical methods, open techniques and systematic observation of sport activity. Determination was made of parameters which diagnose motivation, among them the ten wishes technique, phrase composition and completion, interviews and three weeks' observation. Results: The main results contributed determination of the cognitive, emotional and conative components of motivation for sports and the corresponding indicators. Conclusions: In the boxing team sport reasons do not effectively guide personality toward achieving the best possible performance in sport activity (AU)