Flight time is the most accurate and frequently used variable when assessing the height of vertical jumps. The purpose of this study was to analyze the validity and reliability of an alternative method (i.e., the HSC-Kinovea method) for measuring the flight time and height of vertical jumping using a low-cost high-speed Casio Exilim FH-25 camera (HSC). To this end, 25 subjects performed a total of 125 vertical jumps on an infrared (IR) platform while simultaneously being recorded with a HSC at 240 fps. Subsequently, 2 observers with no experience in video analysis analyzed the 125 videos independently using the open-license Kinovea 0.8.15 software. The flight times obtained were then converted into vertical jump heights, and the intraclass correlation coefficient (ICC), Bland-Altman plot, and Pearson correlation coefficient were calculated for those variables. The results showed a perfect correlation agreement (ICC = 1, p < 0.0001) between both observers' measurements of flight time and jump height and a highly reliable agreement (ICC = 0.997, p < 0.0001) between the observers' measurements of flight time and jump height using the HSC-Kinovea method and those obtained using the IR system, thus explaining 99.5% (p < 0.0001) of the differences (shared variance) obtained using the IR platform. As a result, besides requiring no previous experience in the use of this technology, the HSC-Kinovea method can be considered to provide similarly valid and reliable measurements of flight time and vertical jump height as more expensive equipment (i.e., IR). As such, coaches from many sports could use the HSC-Kinovea method to measure the flight time and height of their athlete's vertical jumps.

The Concurrent Validity and Reliability of a Low-Cost, High-Speed Camera-Based Method for Measuring the Flight Time of Vertical Jumps

Purpose: The purpose of this investigation was to compare sprint and countermovement-jump (CMJ) performance among female competitive soccer players as a function of performance level, field position, and age. In addition, the authors wanted to quantify the evolution of these physical characteristics among elite players over a 15-y period. Methods: 194 female elite players (22± 4.1 y, 63 ± 5.6 kg), including an Olympic winning squad, tested 40-m sprint with electronic timing and CMJ on a force platform at the Norwegian Olympic training center from 1995 to 2010. Results: Moderate to large velocity differences across performance levels and positions were observed. National-team players were 2% faster than 1st-division players (P = .027, d = 0.5) and 5% faster than 2nd-division players (P < .001, d = 1.3) over 0–20 m. National-team players jumped 8–9% higher than 1st-division players (P = .001, d = 0.6) and junior elite players (P = .023, d = 0.5). Forwards were 3–4% faster than midfielders (P < .001, d = 0.8...

Speed and countermovement-jump characteristics of elite female soccer players, 1995-2010.

Fourteen male elite sprinters performed short-distance sprints and jump tests until 18 days before 100-m dash competitions in track and field to determine if these tests are associated with 100-m sprint times. Testing comprised of squat jumps (SJ), countermovement jumps (CMJ), horizontal jumps (HJ), maximum mean propulsive power relative to body mass in loaded jump squats, and a flying start 50-m sprint. Moderate associations were found between speed tests and competitive 100-m times (r = 0.54, r = 0.61, and r = 0.66 for 10-, 30-, and 50-m, respectively, p ≤ 0.05). In addition, the maximum mean propulsive power relative to body mass was very largely correlated with 100-m sprinting performance (r = 0.75, p < 0.01). The correlations of SJ, CMJ, and HJ with actual 100-m sprinting times amounted to -0.82, -0.85, and -0.81, respectively. Because of their practicality, safeness, and relationship with the actual times obtained by top-level athletes in 100-m dash events, it is highly recommended that SJ, CMJ, and HJ be regularly incorporated into elite sprint-testing routines.

Vertical and Horizontal Jump Tests Are Strongly Associated With Competitive Performance in 100-m Dash Events.

The neuromechanical determinants of sprint running performance have been investigated in team sports athletes and non-elite sprinters. The aim of this study was to quantify the relationships between kinetic and performance parameters, obtained in loaded and unloaded vertical and horizontal jumps, and sprinting in elite athletes. Twenty-two sprinters performed squat jumps, countermovement jumps, horizontal jumps, and jump squats with different loads on a force platform, in addition to a 50-m sprint. Results indicated that jumping height and distance in vertical and horizontal jumps are more strongly correlated (R ≈ 0.81) to sprinting speed than the respective peak forces (R ≈ 0.36). Furthermore, the optimum load generating the maximum power in the jump squat is also highly correlated to sprint performance (R ≈ 0.72). These results reveal that vertical and horizontal jump tests may be used by coaches for assessing and monitoring qualities related to sprinting performance in elite sprinters.

Relationship between sprint ability and loaded/unloaded jump tests in elite sprinters.

The capacity to rapidly generate and apply a great amount of force seems to play a key role in sprint running. However, it has recently been shown that, for sprinters, the technical ability to effectively orient the force onto the ground is more important than its total amount. The force-vector theory has been proposed to guide coaches in selecting the most adequate exercises to comprehensively develop the neuromechanical qualities related to the distinct phases of sprinting. This study aimed to compare the relationships between vertically-directed (loaded and unloaded vertical jumps, and half-squat) and horizontally-directed (hip-thrust) exercises and the sprint performance of top-level track and field athletes. Sixteen sprinters and jumpers (including three Olympic athletes) executed vertical jumps, loaded jump squats and hip-thrusts, and sprinting speed tests at 10-, 20-, 40-, 60-, 100-, and 150-m. Results indicated that the hip-thrust is more associated with the maximum acceleration phase (i.e., from zero to 10-m; r = 0.93), whereas the loaded and unloaded vertical jumps seem to be more related to top-speed phases (i.e., distances superior to 40-m; r varying from 0.88 to 0.96). These findings reinforce the mechanical concepts supporting the force-vector theory, and provide coaches and sport scientists with valuable information about the potential use and benefits of using vertically- or horizontally-based training exercises.

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Vertically and horizontally directed muscle power exercises: Relationships with top-level sprint performance

The purpose of this study was to investigate the relationships among jumping performances and speed parameters during maximum speed phase in sprinters. Twenty-one men sprinters volunteered to participate at the beginning of the preparation training phase. All tests-including 100-m sprint running, squat jump (SJ), countermovement jump (CMJ), drop jump (DJ), 60-second repetitive jump (RJ), standing long jump (SLJ), standing triple jump (STJ), standing quintuple jump (SQJ), and standing 10-stride jump (STENJ)-were done on switching mats. Flight (FT) and contact times (CT) during the vertical jump tests and 10-m split times during 100-m sprint running were measured by a 2-channel precision timing system (PTS) connected to the mats. The trace marking method was used for measuring the stride length (SL) through 60 m in 100-m sprint running. Stride frequency (SF), maximum velocity (Vmax), jump height for all vertical jumps, and lower-body power in DJ and RJ were calculated. Statistical analysis showed that the highest significant correlation was found between Vmax and DJ height (r = 0.69; p < 0.05). However, the lowest significant correlation coefficient was found between SL at maximum velocity phase of sprint running and SJ (r = 0.39; p < 0.05). In conclusion, DJ height is demonstrated to be a more effective way to reflect Vmax during sprint running than the other vertical and horizontal jump tests at the beginning of the preparation training phase.

Relationships among jumping performances and sprint parameters during maximum speed phase in sprinters.

IntroductionThe possibility to generate contractile activity of a muscle with an electrical current application on the neuromuscular system has been known since the 18th century (Bax et al., 2005; Vanderthommen and Duchateau, 2007). The number of Electromyostimulation (EMS) studies has been enlarged in the last 30 years on healthy individuals and EMS has been paid attention as a new training method for athletes. Yakov Kotz has claimed that increased muscle strength (~%40) after short-term EMS training program with high frequency caused this interest. There are a lot of studies (Strauss and Domenico, 1986; Holcomb, 2005; Kraemer and Mendryk, 1982; Komi, 2008; Porcari et al., 2002; Walmsley et al., 1984; Yanagi et al., 2003) supporting or opposing these results in literature.High-frequency EMS training has increased its popularity as a method of strength training to increase maximal voluntary strength of the lower limb muscles among healthy individuals and elite athletes in the last few years (Maffiuletti et al., 2002a; Maffiuletti et al., 2002b; Malatesta et al., 2003; Marqueste et al., 2010; Taifour et al., 2013). EMS has been accepted to be an important complement in rutin strength training programs for the enhancement of athletic performance (Thorstensson et al., 1976) because it can provide more intense contraction to the stimulated muscle and thereby induce greater adaptive responses (Borniquez et al., 1993; Maffiuletti et al., 2000). LB-EMS application is an effective training method to enhance lower body power that provides intense contraction to the stimulated leg muscles and thereby induces greater adaptive responses. Local EMS application have shown positive effects on neuromuscular parameters in athletes and healthy individuals; however; there are a few multi-joint EMS studies on the effects of athletic performance and therefore, the feasibility and acceptability of this new training technology have turned out to be an important point (Kemmler et al., 2012; Kraemer and Mendryk, 1982; Kale et al., 2014; Komi, 2008, Vanderthommen and Duchateau, 2007; Porcari et al., 2002).Acute EMS applications produced the similar physiological effects as conventional aerobic exercises. Some studies have indicated that EMS training combined with aerobic exercises cause more energy consumption (%17) than aerobic exercises (Kemmler et al., 2012; Hennessy et al., 2010). Therefore it is necessary to study on the acute effects of EMS application on explosive power performances. In different EMS protocols, theoretically, partial or complete neuromuscular adaptations seem possible, but the physiological effects are different from each other. Also acute and chronic effects of EMS are still not clear. There are limited studies on the effect of a single EMS training session on isokinetic strength and jumping performance. The purpose of the present study was to investigate the acute effects of a lower body electromyostimulation (LB-EMS) bout on maximal isokinetic strength of the dominant knee extensor-flexor muscles and vertical jumping performance.Materials and MethodsIn these study vertical jump including squat jump (SJ) to assess explosive power and counter movement jump (CMJ) to assess elastic strenght performance of the lower extremity are tested. Maximal isokinetic strength test of the knee extensor-flexor muscles at different angular velocities is also an acceptable test to evaluate leg power. Heights of SJ and CMJ, and isokinetic maximal knee extensor-flexor torque values at three angular velocities were assessed to examine the acute effects of LB-EMS during static squat movement. A randomized crossover trial with moderately trained men was used to address the hypothesis of the acute effect of LB-EMS during static squat movement on jumping performance and knee extensor-flexor torque values at three angular velocities (60, 180 and 3002/s) of two different frequencies (low=30Hz and high=100Hz) with the control condition frequency (0Hz). …

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Acute Effects of Lower Body Electromyostimulation Application with Two Different Frequencies on Isokinetic Strength and Jumping Performance

Purpose: Electromyostimulation is a popular training to increase muscle strength during the last years. The aim of this study was to investigate effects of electromyostimulation training on jumping and muscle strength in football players. Material: Volunteered 23 football players between the ages of 18 to 24 were divided into experimental and control groups with simple random sampling. Both groups continued to regular training. Experimental group had additional electromyostimulation training for 6-week, 3-time a week, and 20min a day. Pre- and post-training squat and countermovement jumps, peak torques of dominant and non-dominant knee extensor and flexor muscles were tested. Angular velocities of isokinetic dynamometer were 60, 180, and 300ºs-1. Pre- and post-test comparisons within the groups were analyzed. Results: There were no significant differences between pre- and post-test for isokinetic knee strength parameters at all angular velocities of EG. However, control group had significant pre- and post-test differences in dominant and non-dominant knee extension and flexion peak torque values. Conclusions: EMS and regular training in-season had no effect on the isokinetic strength parameters. On the other hand, the regular training in-season has increased isokinetic strength. Electromyostimulation training additional to regular training may have detrimental effects on outcomes of concurrent training in football players.

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Effects of electromyostimulation training on jumping and muscle strength in football players

Baslangicta rehabilitasyon ve tedavi amacli olarak uygulanan elektromyostimulasyon (EMS) daha sonra populer bir antrenman yontemi olarak antrenorlerin, sporcularin ve spor bilimcilerin ilgisini cekmistir. EMS, kas dokusu ya da motor noktalar uzerine uygulanan elektriksel akimlar olarak tanimlanabilir. Elektriksel uyarili ve istemli kasilmalar sirasinda kaslar farkli sekilde aktive olmaktadir. Yapilan calismalar EMS antrenmanlarinin kas hipertrofisi icin gereken kas kuvvetini daha kisa zamanda arttirdigini ve istatistiksel olarak anlamli bir hipertrofi olmaksizin artan kuvvetin noral gelisimin en onemli kaniti oldugunu gostermektedir. EMS antrenmanlarinin maksimal istemli kuvvette artis saglamasi spinal ve supraspinal merkezlerden aktif kaslara olan noral suruste, spinal uyarilabilirlikte, aktive olan motor unite miktarinda ve senkronizasyonunda artis olasiligini da akla getirmektedir. Bunun yaninda unilateral uygulanan EMS antrenmanlarinin kontralateral homolog kasta da kuvvet artislari saglamasi EMS antrenmanlarinin supraspinal merkezleri ve farkli kortikal bolgeleri etkiledigini gostermektedir. Bu kapsam dahilinde yapilan calismalarin isiginda derlemenin amaci EMS antrenmanlarina dayali noral adaptasyonlar ve EMS antrenmanlarinin sedanter ve sporcularin sportif performanlarinda meydana getirdigi etkileri incelemektir.

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Elektromyostimülasyon Antrenmanlarının Nöral Adaptasyon ve Sportif Performans Üzerine Etkileri

Abstract The purpose of this study was to investigate the effects of additional short and long running stride workouts on acceleration kinematics and jumping performances with respect to the competition phase. Thirteen voluntary male sprinters participated in this study (100 m PB: 10.45-11.30s). The sprinters were separated into three groups [control group (CG), short stride group (SSG), long stride group (LSG)] in a randomised order. Sprinters continued their competition phase training over a two-week period; however, the SSG and LSG run an additional 6 × 40 m three times per week. The pre- and post-training results regarding, acceleration kinematics and jumping performances were compared using the Kruskal Wallis test for several independent samples of intergroup and the Wilcoxon Two Related Samples Test for intragroup differences. If there were intergroup differences, the Mann Whitney U test was used for two related comparisons of the groups. The probability level for statistical significance was set to p≤0.05. Only the LSG showed significant pre- and post-training differences with respect to certain acceleration kinematics (sprint time, sprint velocity, stride length) (Z= −2.023, 2.032, 2.060, respectively; p<0.05). In conclusion, the results of this study show that there is no significant effect of a two-week training regimen involving additional long and short stride running workouts on Turkish sprinters in the competition phase; however, long stride running workouts may be useful for sprinters who have short stride sprint characteristics.

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Mehmet Kale

Papers

Relationships among jumping performances and sprint parameters during maximum speed phase in sprinters.

Acute Effects of Lower Body Electromyostimulation Application with Two Different Frequencies on Isokinetic Strength and Jumping Performance

Effects of electromyostimulation training on jumping and muscle strength in football players

Elektromyostimülasyon Antrenmanlarının Nöral Adaptasyon ve Sportif Performans Üzerine Etkileri

Effects of stride length and frequency training on acceleration kinematic, and jumping performances