exercise for both the single-leg hop for distance as well as jump height and ground contact time during the 4-jump test. Methods Participants A total of 52 individuals volunteered for this study consisting of 27 patients with ACLR and 25 matched healthy, uninjured controls (Table 1 ). Based on an a priori
Haley Bookbinder, Lindsay V. Slater, Austin Simpson, Jay Hertel and Joseph M. Hart
Blair Mills, Brad Mayo, Francisco Tavares and Matthew Driller
-flossing intervention in lesser-trained participants. Furthermore, they also reported a significant treatment and time interaction for FLOSS when compared with CON for a WBLT. The baseline ROM, sprint, and jump test results in the current study were considerably higher/faster than in the previous study by Driller et
Juan J. Salinero, Cristina González-Millán, Javier Abián-Vicén and Juan Del Coso Garrigós
The goal of dorsiflexion sports shoes is to increase jumping capacity by means of a lower position of the heel in relation to the forefoot which results in additional stretching of the ankle plantar flexors. The aim of this study was to compare a dorsiflexion sports shoe model with two conventional sports shoe models in a countermovement jump test. The sample consisted of 35 participants who performed a countermovement jump test on a force platform wearing the three models of shoes. There were significant differences in the way force was manifested (P < 0.05) in the countermovement jump test, with a decrease in the velocity of the center of gravity and an increase in force at peak power and mean force in the concentric phase. Moreover, peak power was reached earlier with the dorsiflexion sports shoe model. The drop of the center of gravity was increased in CS1 in contrast to the dorsiflexion sports shoe model (P < .05). However, the dorsiflexion sports shoes were not effective for improving either peak power or jump height (P > .05). Although force manifestation and jump kinetics differ between dorsiflexion shoes and conventional sports shoes, jump performance was similar.
Boyi Dai, Christopher J. Sorensen, Timothy R. Derrick and Jason C. Gillette
The effects of training on biomechanical risk factors for anterior cruciate ligament (ACL) injuries have been investigated, but the effects of detraining have received little attention. The purpose of this study was to evaluate the effects of a one-month postseason break on knee biomechanics and lower extremity electromyography (EMG) during a stop-jump task. A postseason break is the phase between two seasons when no regular training routines are performed. Twelve NCAA female volleyball players participated in two stop-jump tests before and after the postseason break. Knee kinematics, kinetics, quadriceps EMG, and hamstring EMG were assessed. After one month of postseason break, the players demonstrated significantly decreased jump height, decreased initial knee flexion angle, decreased knee flexion angle at peak anterior tibial resultant force, decreased prelanding vastus lateralis EMG, and decreased prelanding biceps femoris EMG as compared with prebreak. No significant differences were observed for frontal plane biomechanics and quadriceps and hamstring landing EMG between prebreak and postbreak. Although it is still unknown whether internal ACL loading changes after a postseason break, the more extended knee movement pattern may present an increased risk factor for ACL injuries.
Thorsten Schiffer, Anne Möllinger, Billy Sperlich and Daniel Memmert
The application of kinesio tape (KT) to lower-extremity muscles as an ergogenic aid to improve muscle-strength-related parameters such as jumping is controversial.
To test the hypothesis that the application of KT enhances the jumping performance of healthy uninjured elite female track and field athletes.
A double 1-legged jump test was performed before and after the application of blue K-Active tape without traction on the maximally stretched gastrocnemius, hamstrings, rectus femoris, and iliopsoas muscles according to the generally accepted technique.
18 German elite female track and field athletes (age 21 ± 2 y, height 172 ± 4 cm, body mass 62 ± 5 kg, active time in their sport 13 ± 4 y).
Factorial analysis of variance with repeated measures (ANOVA, Bonferroni) revealed no significant differences in jumping performance between the tests (P > .05, d = 0.26).
These findings suggest that the application of KT has no influence on jumping performance in healthy, uninjured female elite athletes. The authors do not recommend the use of KT for the purpose of improving jump performance.
Kam-Ming Mok, Eirik Klami Kristianslund and Tron Krosshaug
Knee valgus angles measured in sidestep cutting and vertical drop jumps are key variables in research on anterior cruciate ligament (ACL) injury causation. These variables are also used to quantify knee neuromuscular control and ACL injury risk. The aims of the current study were to (1) quantify the differences in the calculated knee valgus angles between 6 different thigh marker clusters, (2) investigate the trial ranking based on their knee valgus angles, and (3) investigate the influence of marker clusters on the cross-talk effect. Elite female handball and football players (n = 41) performed sidestep cutting and vertical drop jumping motions. We found systematic differences up to almost 15° of peak valgus between the marker sets in the drop jump test. The Spearman’s rank correlation coefficient varied from .505 to .974 among the 6 marker sets. In addition, the cross-talk effect varied considerably between the marker clusters. The results of the current study indicate that the choice of thigh marker cluster can have a substantial impact on the magnitude of knee valgus angle, as well as the trial ranking. A standardized thigh marker cluster, including nonanatomical landmark, is needed to minimize the variation of the measurement.
Jorg Teichmann, Edin K. Suwarganda, C. Martyn Beaven, Kim Hébert-Losier, Jin Wei Lee, Florencio Tenllado Vallejo, Philip Chun Foong Lew, Ramlan Abdul Aziz, Yeo Wee Kian and Dietmar Schmidtbleicher
Jump Test: The test procedure started with a standard 20 min warm-up inclusive of dynamic stretching and 5 min cycling on a stationary bike. Subsequently, 3 maximal effort unloaded vertical countermovement jumps were performed on a contact mat (Swift Performance Equipment, Australia) with the hands on
Zachary M. Gillen, Lacey E. Jahn, Marni E. Shoemaker, Brianna D. McKay, Alegra I. Mendez, Nicholas A. Bohannon and Joel T. Cramer
Vertical jump tests are among the most popular assessments of lower-body power for athletes. 1 – 6 Arguably, the most popular and common vertical jump test is the countermovement jump (CMJ). The CMJ involves a downward, eccentric movement followed by a rapid, maximal, upward, concentric vertical
Sean J. Maloney, Joanna Richards and Iain M. Fletcher
tasks expose the athlete to GRFs of greater magnitude and may result in greater vertical stiffness values. 14 When performing drop jump tests, coaches and practitioners often seek to determine the reactive strength index (RSI). The RSI may be calculated from a drop jump by dividing either flight time 15
Kajetan J. Słomka, Slobodan Jaric, Grzegorz Sobota, Ryszard Litkowycz, Tomasz Skowronek, Marian Rzepko and Grzegorz Juras
output as an index of the maximal capacity of the leg muscles to produce force and power. However, the most frequently recorded variable observed from the vertical jump tests is maximum jump height, which is typically interpreted as an index of the capacity of a muscle to produce either a high force or