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DSJ (vertical jump without counter-movement from bending the knees over 120º) and the 30m sprint from the rest. Martín Acero Rafael Universidad de La Coruña - UDC - Facultad de CC. del Deporte y la E. F. - Coruña - Espanha [email protected] Miguel Fernández Del Olmo Universidad de La Coruña - UDC - Facultad de CC. del Deporte y la E. F. - Coruña - Espanha [email protected] Oscar Viana González Universidad de La Coruña - UDC - Coruña - Espanha [email protected] Xavier Aguado Jodar Universidad de Castilla-La Mancha - UCLM - Facultad de Ciencias del Deporte - Castilla-La Mancha - Espanha [email protected] Francisco J Vizcaya Pérez Instituto de Ciencias Aplicadas al Entrenamiento - Leipzig - Alemanha [email protected]

Acero R M, Fernande-del-Olmo M, Viana O V, Aguado X, Vizcaya F J. [2008] DSJ (vertical jump without counter-movement from bending the knees over 120ş) and the 30m sprint from the rest.

Fit Perf J. 2008 Sep-Oct;7 (5): 319-25 doi:10.3900/fpj.7.5.319..

ABSTRACT Introduction: The vertical jump test without counter movement knees flexion larger than 120º (DSJ) is described with its relation with the SJ and CMJ the tests, and with the 30 meters race. Materials and Methods: 58 men accomplished four attempts for each jump test and two attempts for a 30m speed race. A variation coefficient (CV=2.73) is evidenced, which shows the DSJ as a test of great stability. Results: The results showed significant differences (p=0.01) among the obtained values in DSJ and in the SJ and CMJ tests. The correlation analysis among different tests of vertical jump showed high levels of correlation which were statistically significant (p=0.01).The DSJ shows a higher intensity of correlation with the CMJ. When establishing the relation between DSJ and the speed race, the correlations were statistically significant (p=0.01) in all cases, if observing the highest intensity with time in 30m. Discussion: The good reliability shown by the DSJ, its correlation levels with other jump tests (SJ, CMJ) and with the speed race timing show that DSJ is an efficient test to control strength and potency. KEYWORDS - Running, Muscle Strength, Muscle Strength Dynamometer.

DSJ (salto vertical sem contra-movimento a partir de flexão de joelhos acima de 120º) e corrida de velocidade de 30m a partir do repouso RESUMO Introdução: Descreve-se o teste de salto vertical sem contra-movimento a partir da flexão de joelhos acima de 120º (DSJ), sua relação com os testes SJ e CMJ, e com a corrida de 30m.

Materiais e Métodos: 58 homens realizaram quatro tentativas de cada teste de salto e duas tentativas de corrida de velocidade de 30m. Constata-se um coeficiente de variação (CV=2,73) que mostra a DSJ como um teste de grande estabilidade. Resultados: Os resultados mostraram diferenças significativas (p=0,01) entre os valores obtidos em DSJ e nos testes SJ e CMJ. A análise da correlação entre os diferentes testes de salto vertical mostrou níveis altos de correlação estatisticamente significativos (p=0,01). O DSJ mostra uma intensidade de correlação mais alta com o CMJ. Ao estabelecer a relação entre DSJ e a corrida de velocidade, as correlações resultaram estatisticamente significativas (p=0,01) em todos os casos, se observando a maior intensidade com o tempo em 30m. Discussão: A boa confiabilidade mostrada pelo DSJ, seus níveis de correlação com os outros testes de salto (SJ, CMJ) e com os tempos da corrida de velocidade demonstram que DSJ é um teste eficaz para controle da força e a potência. PALAVRAS-CHAVE - Corrida, Força Muscular, Dinamômetro de Força Muscular.

DSJ (salto vertical sin contramovimiento desde flexión de rodillas mayor de 120º) y carrera de velocidad de 30 m desde parado RESUMEN Introducción: Se describe la prueba de salto vertical sin contramovimiento desde flexión de rodillas mayor de 120º (DSJ), su relación con las pruebas SJ y CMJ, y con la carrera de 30m. Materiales y Métodos: 58 varones, realizaron cuatro intentos de cada prueba de salto, y dos intentos de carrera de velocidad de 30m. Se constata un coeficiente de variación (CV = 2,73) que muestra a DSJ como una prueba de gran estabilidad. Los resultados mostraron diferencias significativas (p=0,01) entre los valores obtenidos en DSJ y en las pruebas SJ y CMJ. El análisis de la correlación entre las diferentes pruebas de salto vertical mostró niveles altos de correlación, estadísticamente significativos (p=0,01). El DSJ muestra una intensidad de correlación más alta con el CMJ. Al establecer la relación entre DSJ y la carrera de velocidad, las correlaciones resultaron estadísticamente significativas (p=0,01) en todos los casos, observándose la mayor intensidad con el tiempo en 30m. La buena fiabilidad mostrada por el DSJ, sus niveles de correlación con las otras pruebas de salto (SJ, CMJ), y con los tiempos de la carrera de velocidad, demuestran que DSJ es una prueba eficaz para control de la fuerza y la potencia. PALABRAS CLAVE - Carrera, Fuerza Muscular, Dinamómetro de Fuerza Muscular.

INTRODUCTION In tests of estimative of strength and power of the extensor muscles of the legs have been customary, for many decades, the use of vertical jump, as it is reflected in numerous studies1,2,3,4,5,6,7,8,9. Technological advances enabled more accurately record biomechanical, metabolic and neuromuscular parameters involved in the movement of the vertical jump in different conditions, contributing with very relevant data and allowing its relationship with other manifestations of force. One researcher, highlighted by his enormous contribution to the scientific, technological and methodological evolutions was Carmelo Bosco. His deep and extensive work allowed applying scientific knowledge to control the training, equipping it a more scientific constructo. Among the many contributions made by Bosco, is a set of tests for vertical jump grouped in the so-called Battery of Bosco: Squat Jump (SJ), Countermovement Jump (CMJ) and Drop Jump (DJ). The application in the laboratory and in the field of this battery enabled enriches the strategies and parameters of control and training of the different manifestations of the force produced by the extensor muscles of the legs. Examples are the different indexes and gradients calculated with different magnitudes of resistance to overcome in the vertical jump. The battery of Bosco2 is supplemented with others that, in neuromuscular or energy demand, are the most similar possible to determined specific action or specialty sports. Thus, there are numerous tests with

few variations in the implementation of the vertical jump:

• In tests of more conventional vertical jump (SJ, CMJ) are required an average flexion of the knee joint, which involves relatively less demands of muscles that extend the hip. These muscles are particularly important in sport disciplines where the sport yield is bound to expression of a high speed race26,27. In speed race, in the initial traction phase, for the foot support, the racer of higher level developing an extension of the hip stronger and fast than racers of at lesser level28. In this work presents the vertical jump from the deep bending of the knee, with more than 120º, named Deep Squat Jump: DSJ24,25. DSJ contributes as a test for evaluating the levels of explosive power and muscle potency in the control and direction of the training of sports specialty that require high percentages of the same, especially those that are expressed in speed race. Previous studies have shown that non-experienced adult subjects managed a mean height higher in DSJ that in SJ24, showing significant differences between the two tests. It is also observed significant differences when comparing the heights achieved in DSJ and CMJ, and between DSJ and CMJA (Graph 1). In this study, it is intended to describe the relationship between DSJ test and 30m sprint starting from rest position, and its step time at 10m and 20m. Also with the tests of more conventional vertical jumps (SJ, CMJ). MATERIALS AND METHODS Approval of the study The subjects have given their written consent for participation in this study, which was approved by the Ethics Committee of the Universidad de La Coruna. Subjects Participated 58 subjects, aged between 18 years and 24 years, with a mean body weight (BW) of 72.4kg, a mean height (STA) of 175.4cm and a mean leg length (LL) of 90.67cm, of masculine gender and athletes with previous experience in carrying out the tests of vertical jump, who participated as volunteers in this study.

Procedures The subjects performed two assessment sessions, on separate days, with a minimum of 48h between sessions. In the first session of the tests were performed vertical jump and in the second session the speed race tests. Tests for evaluating the vertical jump ability The subjects performed four maximum attempts of each one of the tests (DSJ, SJ, CMJ) on the contact platform, with a recovery of 60s between each attempt. Tests for SJ and CMJ were conducted under internationally accepted protocols, the DSJ, following recently published protocol24,25. Protocol of the DSJ test To perform the DSJ test, the subjects were placed on the platform in a position (Graph 1: A) of full squat, that is, with maximum bending of the knee joint (b), at an angle greater than 120º and after comparison and Individual motive adjustment of the own subject, with the feet at the same height and separated wit the same width of shoulders and hips, with the heels raised from the ground (a), the trunk lifted and their hands grabbing the waist (c). From this position and after keep it 3-4s, to eliminate any influence of elastic energy accumulated during the decrease in muscle-tendon components29,30, the subjects performed a vertical jump as high as possible without making any kind of counter-movement (Graph 2: B) and keeping the verticality of the trunk, so was indicated to them to sets sight on the horizon. The reception of the jump (Graph 2: C) on the platform will be performed with the knee extended (d) and the ankles in plantar flexion (e), the same way as when the subject off the ground, making some small rebound.

The jump will not be considered valid if it is noticed some movement that bends the knee before starting the impulse, which would have neuromuscular mechanisms that are different of those that will be evaluated. It should also require a vertical displacement as possible, since any change in the trajectory of the gravity center would imply an increase in flight time, and even if will require that in the reception the joints of the knees and ankles are fully extended. Tests for evaluating the acceleration and maximum speed capacities The abilities of acceleration and top speed are evaluated at a covered facility to match the conditions in all subjects and repetitions. The race was performed on a corridor of synthetic material, with non-specific sports shoes. Were performed two attempts at maximum intensity of the test of 30m race starting (output) at the rest position of the, following the internationally accepted protocol. The subjects were completely recovered before performing another attempt. The photocell of the IMT were placed at the start, 10m, 20m and 30m, so during the speed race tests was recorded the time used to travel the distance from the exit at 10m (T0-10) from the exit at 20m (T0-20), and since the departure at 30m (T0-30). Statistical analysis First it was calculated the coefficient of variation (CV) for the jump height in order to determine the stability of the measurements between attempts for each one of the tests for vertical jump. Continuing, in each subject, the mean is calculated for each type of jump and was carried out to perform ANOVA of repeated measures with an intra-subject factor (jump type: 4 levels). In case of a significant effect and in order to establish in how many kinds of jump occurred significant differences, were carried out post-hoc comparisons using the Student’s "t" test for samples related to the correction factor of Bonferroni. The level of significance was set at p=0.05. We used the Pearson’s coefficient correlation and performed the regression analysis to demonstrate the relationship between variables and the jump ability between these and those discussed during the test in 30m sprint race, starting from the rest position. Were performed tests to check the validity of the achieved models and fulfilled all the supposed linear regression models. RESULTS The results obtained in jump height in the tests of vertical jump (mean ± standard deviation) and their coefficients of variation are presented in Table 2. Regarding the reliability between repetitions, we can prove that in the vertical jump tests, the coefficients of variation (CV) were more than acceptable. From this study can be seen that DSJ is a test with a great stability in taken measurements, as shows the coefficient of variation obtained for this counter-movement jump without maximum bending of the knees (CV=2.73).

The time performed at the test of 30m sprint starting from rest position, as well as the times until 10m and 20m can be seen in Table 4.

DISCUSSION As in other previous studies, performed with samples of similar characteristics, gender and age, in this research could prove low coefficient of variation (CV=2.98) for CMJ (Vittasalo31 found a CV=4.30, and López32 a CV=3.03), should take into account that in this study for students of physical education is required previous experience in vertical jumps. For SJ was found a more than acceptable CV (3.82). Was contributed to these finding good reproducibility in measurements in DSJ, as shown in the CV (2.73), analyzed, and the best value for stability in measurements made between repetitions of the three types of jump of this study: DSJ, CMJ and SJ. The results of this study show similar values to those found literature5,29 for samples with similar characteristics, both in vertical jump tests and in the 30m sprint test33. By comparing the height reached between the tests conducted under predominantly concentric conditions (DSJ and SJ) and those performed (CMJ) in a position to exploit the stretch shortening cycle (SSC), significant differences were observed, coinciding with the results obtained in numerous studies which try to explain the contribution of SSC for the implementation of vertical jump3,33,34,35,36,37,38,39. The differences in the jump height reached under SSC (CMJ), when comparing with SJ was 0.04m, and when comparing with DSJ, resulted from 0.009m. The differences coincide with the contributions of Young40, which refers to 12.1% increase compared to the CMJ and SJ. However, these differences are minimized regarding the DSJ, whose income is more seems to hit at CMJ than the obtained in SJ. Resulted very similar magnitude of two performances of reached mean height, but produced in very different neuromuscular conditions. When comparing the two tests without counter-movement (SJ and DSJ), we can show how the mean height reached is greater when performed the DSJ. This difference in favor of DSJ could be explained by the possibility of applying force for longer time, a higher trajectory of the route of the center of gravity and reach a maximum speed of implementation of greater magnitude24. Clearly, these DSJ characteristics are determined by the articular angle of the levers that, when making the movement, also change the length of the working muscles of the involved joints, the integration angle between them and the bones that they were formed. The change in articular angle produces a clear change of time during which the muscles can produce power, so that an appropriate use of the trajectory of an acceleration will great permit transmission of impulses, with the goal of increasing the speed of take-off41, which will result an increase of the reached height, as resulted in the present study when modifying, as a contribution of the DSJ test with respect to SJ, the maximum possible bending of the knee joint (higher than 120°). In several old20 and recent21,22 investigations, showed that the angle of the knee in the starting position as counter-movement without affecting the jump height, finding optimum angle around 115º. However, in these studies, they did not find what happened when performing the jump from a starting position of knee joint bending over 120º, without counter-movement. In other recent work42, where it was wanted to know the physical characteristics that could better predict the performance on the vertical jump, was proved that even if the bending degree of the knee joint was not decisive, had an important role in the reached height. One purpose of this study was to prove the link between the vertical jump tests and the test of the 30m sprint, resulting that all the jumps (SJ and CMJ) showed significant correlations with the sprint test, as showed the previous investigations33,43. The current survey also found that the test of DSJ jumping had a significant correlation with the sprint test. When observing the correlation coefficients of DSJ with the partial and final times recorded in the sprint test, was identified an increase parallel to the increase in the time length, it is suggested further studies to better understand the relationship between the strength onset in DSJ and the increase in speed. Further research should establish the size of the influence of the hip extensor muscles in both sprint and jump in DSJ, and thus could reassert contributions already assumed in the literature when it was reported that the acceleration of the sprint, the time of contact is longer than when it was already reached the maximum speed, mainly in the action of flexion/extension of the knee, while reaching the point of maximum speed, predominating the action of hip extension8,44,45,46,47. Taking into account the results of this study, as the relationship between DSJ test and the other battery of tests of Bosco (SJ, CMJ), the relationship of DSJ with 30m sprint, as well as the good reliability of vertical jump, DSJ can be regarded as an effective tool for evaluating the sports performance in relation to the force and other explosive events derived from it. Through the records in DSJ, can be quantified the performance of the jump with higher demand in neuromuscular concentric contraction of the extensors of the hip and knee.

Conducted a linear regression model, depending on the time recorded in different vertical jumps, to explain the performance in the 30m sprint starting from rest position, we can estimate the race time of the sprint with the single completion of CMJ, which explains a variance of 53%. This model, from just one vertical jump, is very useful for practical application to predict their performance knowing the height reached in CMJ: ...............................................T0-30= 5.365 - 0.031*CMJ His application will be higher in relation to the 30m sprint starting from rest position, using it to predict or to control its maintenance. However, should take place several predicted models for different sports specialties and levels of performance. Other studies show if DSJ can explain some variables of the speed race, in different circumstances than those examined in this study. REFERENCES 1. Cavagna GA, Dusman B, Margaria R. Positive work done by a previously stretched muscle. J Appl Physiol. 1968;24:21-32 2. Bosco C, Komi PV. Mechanical characteristics and fibber composition of human leg extensor muscles. Eur J Appl Physiol. 1979;41:275-84. 3. Bosco C. El entrenamiento de fuerza en el voleibol. Revista de Entrenamiento Deportivo. 1988;2(5-6):57-62. 4. Bosco C. La valutazione della forza con il test di Bosco. Roma: Stampa Sportiva; 1992. 5. Bosco C. La evaluación de la fuerza con el test de Bosco. Madrid: Paidotribo; 1994. 6. Bosco C. La fuerza muscular. Aspectos metodológicos. Barcelona: Inde; 2000. 7. Bosco C, Tihanyi P, Komi PV, Fekete G, Apor P. Store and recoil of elastic energy in slow and fast types of human skeletal muscles. Acta Physiol Scand. 1982;114:543-50 8. Vittori C. El entrenamiento de la fuerza para el sprint. Revista de Entrenamiento Deportivo. 1990;4(3):2-8. 9. Komi PV. Strength and power in sport. Oxford: Blackwel Scientific; 1992. 10. Barber S, Franck B, Noyes F, Mangine R, Mccloskey J, Hartman W. Quantitative assessment of functional limitations in normal and anterior cruciate ligament deficient knees. Clinic Orthop Rel Res. 1990;255:204-14. 11. Smith DJ, Roberts D, Watson B. Physical, physiological and performance differences between Canadian national team and universiade volleyball players. J. Sports Sci. 1992;10(2):131-8. 12. Driss T, Vandewalle H, Monod H. Maximal power and force-velocity relationships during cycling and cranking exercises in volleyball players. Correlation with the vertical jump test. J Sports Med Phys Fitness. 1998;38:286-93. 13. Kakihana W, Suzuki S. The EMG activity and mechanics of the running jump as a function of takeoff angle. J Electromyogr Kinesiol. 2001;11:365-72. 14. Bosco C, Luhtanen P, Komi PV. A simple method for measurement of mechanical power in

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