The Reactive Strength Index in Unilateral Hopping for Distance and Its Relationship to Sprinting Performance: How Many Hops Are Enough for a Comprehensive Evaluation? (original) (raw)
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The Journal of …, 2009
Meylan, C, McMaster, T, Cronin, J, Mohammad, NI, Rogers, C, and deKlerk, M. Single-leg lateral, horizontal, and vertical jump assessment: reliability, interrelationships, and ability to predict sprint and change-of-direction performance. J Strength Cond Res 23(4): 1140-1147, 2009-The purposes of this study were to determine the reliability of unilateral vertical, horizontal, and lateral countermovement jump assessments, the interrelationship between these tests, and their usefulness as predictors of sprint (10 m) and change-of-direction (COD) performance for 80 men and women physical education students. Jump performance was assessed on a contact mat and sprint, and COD performances were assessed using timing lights. With regard to the reliability statistics, the largest coefficient of variation (CV) was observed for the vertical jump (CV = 6.7-7.2%) of both genders, whereas the sprint and COD assessments had smallest variability (CV = 0.8 to 2.8%). All intraclass correlation coefficients (ICC) were greater than 0.85, except for the men's COD assessment with the alternate leg. The shared variance between the single-leg vertical, horizontal, and lateral jumps for men and women was less than 50%, indicating that the jumps are relatively independent of one another and represent different leg strength/power qualities. The ability of the jumps to predict sprint and COD performance was limited (R 2 , 43%). It would seem that the ability to change direction with 1 leg is relatively independent of a COD with the other leg, especially in the women (R 2 , 30%) of this study. However, if 1 jump assessment were selected to predict sprint and COD performance in a test battery, the single-leg horizontal countermovement jump would seem the logical choice, given the results of this study. Many of the findings in this study have interesting diagnostic and training implications for the strength and conditioning coach.
Assessing Reactive Strength Measures in Jumping and Hopping Using the Optojump™ System
Journal of Human Kinetics, 2016
The aim of this study was to assess the concurrent validity of the Optojump™ system (Microgate, Bolzano, Italy) versus a force platform in the estimation of temporal and reactive strength measures. In two separate investigations, twenty physically active males performed double-leg and single-leg drop jumps from a box height of 0.3 m and a 10 s vertical bilateral hopping test. Contact time, flight time and total time (the sum of contact and flight time) were concurrently assessed during single and double-leg drop jumps and during hopping. Jump height, the reactive strength index and the reactive strength ratio were also calculated from contact time and flight time. Despite intraclass correlation coefficients (ICCs) for all variables being close to 1 (ICC > 0.975), a significant overestimation was found in contact time (0.005 ± 0.002 s) and underestimations in flight time (0.005 ± 0.003 s), the reactive strength index (0.04 ± 0.02 m·s-1) and the reactive strength ratio (0.07 ± 0.04...
Maximal unilateral leg strength correlates with linear sprint and change of direction speed
2012
Title (in English) Maximal unilateral leg strength correlates with linear sprint and change of direction speed Title (pa svenska) Maximal enbensstyrka korrelerar med linjar sprint och snabbhet i riktningsforandringar Author (s): Arin, A., Jansson, D. & Skarphagen, K. Institute: Department of Food and Nutrition, and Sport Science University of Goteborg P.O Box 300 S-405 30 Goteborg SWEDEN Essay: xx ECTS Programme/course: Sports Coaching Level: Basic Semester/year: Vt/2012 Tutor: Jesper Augustsson Nr. in serie: xx (ifylles ej av studenten/studenterna)
Journal of Strength and Conditioning Research, 2015
1 Fourteen male elite sprinters performed short-distance sprints and jump tests up to 2 18 days prior to 100-m dash competitions in track & field to determine if these tests are 3 associated with 100-m sprint times. Testing comprised squat jumps (SJ), countermovement 4 jumps (CMJ), horizontal jumps (HJ), maximum mean propulsive power relative to body 5 mass in loaded jump squats (MPPR) and a flying start 50-m sprint. Moderate associations 6 were found between speed tests and competitive 100-m times (r = 0.54, r = 0.61 and r = 7 0.66 for 10-, 30-and 50-m, respectively, P < 0.05). In addition, the MPPR was very largely 8 correlated with 100-m sprinting performance (r = 0.75, P < 0.01). The correlations of SJ, 9 CMJ and HJ with actual 100-m sprinting times amounted to -0.82, -0.85 and -0.81, 10
Influence of Jumping Measures and Squat 1RM on Sprint Speed in Rugby Union Players
This study examined the relationship of countermovement (CMJ), squat (SJ), and rebound jumps (RBJ), estimated 1RM back squat (SQ), contact time (CT) and Reactive Strength Index (RSI) for the RBJ to 30 m sprint time of sub-elite, semi-professional Rugby Union players. The results show that with the exception of SQ and CT, all variables were significantly (p < 0.001) correlated to each other (r > .575). The best determinant of predicting 30 m sprint time was RSI. The relationships of SJ, CMJ, and RBJ jump height and RSI to 30 m sprint time suggest that these rapid movements are all common in Rugby Union players. The results show that estimated 1 RM back squat has little influence on sprint performance. INTRODUCTION: Rugby is a demanding sport that requires high levels of speed strength and agility. Players need to exhibit explosive starts that can be translated to speed and maintained for both short (10 m) and extended (30 m) bursts. Fitness and performance in Rugby have often b...
Applied Sciences
In sports practice, motor tests are commonly used to predict success in specific segments of sprint running, as well as post-injury tests in rehabilitation. The purpose of this analytical cross-sectional study was to determine the prognostic validity of the unilateral horizontal cyclic jumps for a 20 m (UHCJ20m) test on sprint running success. A sample of 118 kinesiology students aged 20.5 ± 1.2 years with an average height of 179.7 ± 6.4 cm and a body mass of 75.6 ± 7.3 kg was used to determine the correlation between the results of the UHCJ20m test and the results of the 20 m sprint start run (MRLS20m), the 20 m sprint flying start run (MRFS20m), and the 100 m run (M100m). The results showed a moderate correlation in all tests (MRLS20m (R = 0.49), MRFS20m (R = 0.53), and M100m (R = 0.38)) with UHCJ20m. In addition to the final result, the multiple regression analysis showed a significant moderate correlation between the kinematic parameters of the UHCJ20m test and the results in t...
Reliability, usefulness, and validity of a repeated sprint and jump ability test
International journal of sports physiology and performance, 2010
Two studies involving 122 handball players were conducted to assess the reliability, usefulness, and validity of a repeated shuttle-sprint and jump ability (RSSJA) test. The test consisted of 6x(2x12.5-m) sprints departing on 25 s, with a countermovement jump performed during recovery between sprints. For the reliability and usefulness study, 14 well-trained male handball players performed the RSSJA test 7 d apart. Reliability of the test variables was assessed by the typical error of measurement, expressed as a coefficient of variation (CV). The minimal changes likely to be "real" in sprint time and jump power were also calculated. For the validity study, players of seven teams (national to international levels, women and men) performed the RSSJA test. CV values for best and mean sprint time were 1.0% (90% CL, 0.7 to 1.6) and 1.0% (90% CL, 0.7 to 1.4). CV values for best and mean jump peak power were 1.7% (90% CL, 1.2 to 2.7) and 1.5% (90% CL, 1.1 to 2.5). The percent spr...
2008
Jonsson Holm, D, Stå lbom, M, Keogh, JWL, and Cronin, J. Relationship between the kinetics and kinematics of a unilateral horizontal drop jump to sprint performance. J Strength Cond Res 22 : 1589-1596, 2008-The aim of this study was to investigate the relationship between the kinematics and kinetics of a singleleg horizontal drop jump (SLDJ) to sprint performance. Twenty regional-level male team-sport athletes gave informed consent to participate in this study. All subjects performed a series of 25-m sprints (measured by dual-beam infrared timing lights) and SLDJ (with both legs) in randomized block order during the same testing session. The SLDJ required the subjects to step downwards off a 20-cm box, land on the force plate (operating at 500 Hz) with the specified foot, and jump for maximal horizontal distance while minimizing ground-contact time. Jump distance, particularly when normalized to a subject's height, was the strongest correlate to sprinting time for all three (5, 10, and 25 m) distances (20.44 , r , 20.65). Multiple linear regression analyses indicated that the SLDJ could account for a high level of variance in sprint time (0.49 , r 2 , 0.68) and that these predictions had a relatively low standard error of estimate (0.02-0.10 seconds). These results further support the contention that jump (particularly horizontal) and sprint ability for short distances are highly related. Whereas practitioners should consider using more horizontal than vertical jumps in the training and testing of most team-sport athletes, additional research into the kinetic determinants of jumping and sprinting may allow a more specific and individualized exercise prescription for improving certain aspects of sprinting such as step length or step rate or the vertical vs. horizontal contributions to propulsion.
Physical Therapy in Sport, 2005
Objectives: The purpose of this study was to: (1) establish the reliability of a new unilateral concentric only horizontal jump assessment (HSJ) then compare the reliability of this test to other types of unilateral vertical and horizontal jumps; (2) compare the tests to whether they differ in their ability to determine limb asymmetries; and (3) investigate the relationship between these jumps and sprint running.
The Reactive Strength Index Reflects Vertical Stiffness During Drop Jumps
International Journal of Sports Physiology and Performance
The Reactive Strength Index (RSI) is often used to quantify drop-jump (DJ) performance; however, not much is known about its biomechanical determinants. The purpose of this study was to investigate the correlations between the RSI and several biomechanical variables calculated from DJ performed with different initial drop heights. Twelve male NCAA Division I basketball players performed DJs from drop heights of 30, 45, and 60 cm. Force plates were used to calculate DJ performance parameters (ie, DJ height, contact time, and RSI) and DJ biomechanical variables (ie, vertical stiffness and eccentric/concentric energetics). Regression analyses were used to assess the correlations between variables at each drop height, and ANOVAs were used to assess the differences of all variables across drop heights. Follow-up analyses used 2 neural networks to determine if DJ performance and biomechanical data could accurately classify DJ trials by drop-height condition. Vertical-stiffness values were...