Improvement of long-jump performance during competition using a plyometric exercise

Purpose: To examine the acute effects of a conditioning plyometric exercise on long-jump performance during a simulated long-jump competition. Methods: Eight national-level track and feld decathletes performed 6 long-jump attempts with a full approach run separated by 10-min recoveries. In the experimental condition subjects performed 3 rebound vertical jumps with maximal effort 3 min before the last 5 attempts, while the 1st attempt served as baseline. In the control condition the participants performed 6 long jumps without executing the conditioning exercise. Results: Compared with baseline, long-jump performance progressively increased only in the experimental condition, from 3.0%, or 17.5 cm, in the 3rd attempt (P =.046, d = 0.56), to 4.8%, or 28.2 cm, in the 6th attempt (P =.0001, d = 0.84). The improvement in long-jump performance was due to a gradual increase in vertical takeoff velocity from the 3rd (by 8.7%, P =.0001, d = 1.82) to the 6th jump (by 17.7%, P =.0001, d = 4.38). Horizontal-approach velocity, takeoff duration, and horizontal velocity at takeoff were similar at all long-jump attempts in both conditions (P =.80, P =.36, and P =.15, respectively). Conclusions: Long-jump performance progressively improved during a simulated competition when a plyometric conditioning exercise was executed 3 min before each attempt. This improvement was due to a progressive increase in vertical velocity of takeoff, while there was no effect on the horizontal velocity. © 2017 Human Kinetics, Inc

Development and psychometric properties of the scale for self-consciousness assessment

This scale development employed Duval and Wicklund's (1972), Carver's (1979), and Zaborowski's (1987) theories on self-consciousness. The aim of the study was to create a new method to assess the self-consciousness construct, in an effort to operationally express self-consciousness, while circumventing existing metric and other impediments. Initially, 38 pilot interviews were conducted with undergraduate psychology students, and two studies followed, one on 494 participants and one on 248 participants. Exploratory factor analysis models, equivalence testing, followed by a third confirmatory factor analysis study on a separate sample of 216 participants, resulted in a final 24-item scale. A four-factor structure of two public and two private self-consciousness dimensions emerged. The Scale for Self-Consciousness Assessment (SSCA) can be of use in various areas of psychological research, possibly in concurrent use with other constructs of interest, due to its theoretical and research importance and its adequate psychometric properties. © Psychological Reports 2012

Acute Improvement of Vertical Jump Performance after Isometric Squats Depends on Knee Angle and Vertical Jumping Ability

Tsoukos, A, Bogdanis, GC, Terzis, G, and Veligekas, P. Acute improvement of vertical jump performance after isometric squats depends on knee angle and vertical jumping ability. J Strength Cond Res 30(8): 2250-2257, 2016 - This study examined the acute effects of maximum isometric squats at 2 different knee angles (90 or 140°) on countermovement jump (CMJ) performance in power athletes. Fourteen national-level male track and field power athletes completed 3 main trials (2 experimental and 1 control) in a randomized and counterbalanced order 1 week apart. Countermovement jump performance was evaluated using a force-plate before and 15 seconds, 3, 6, 9, and 12 minutes after 3 sets of 3 seconds maximum isometric contractions with 1-minute rest in between, from a squat position with knee angle set at 90 or 140°. Countermovement jump performance was improved compared with baseline only in the 140° condition by 3.8 ± 1.2% on the 12th minute of recovery (p 0.027), whereas there was no change in CMJ height in the 90° condition. In the control condition, there was a decrease in CMJ performance over time, reaching -3.6 ± 1.2% (p 0.049) after 12 minutes of recovery. To determine the possible effects of baseline jump performance on subsequent CMJ performance, subjects were divided into 2 groups ("high jumpers" and "low jumpers"). The baseline CMJ values of "high jumpers" and "low jumpers" differed significantly (CMJ: 45.1 ± 2.2 vs. 37.1 ± 3.9 cm, respectively, p 0.001). Countermovement jump was increased only in the "high jumpers" group by 5.4 ± 1.4% (p 0.001) and 7.4 ± 1.2% (p 0.001) at the knee angles of 90 and 140°, respectively. This improvement was larger at the 140° angle (p 0.049). Knee angle during isometric squats and vertical jumping ability are important determinants of the acute CMJ performance increase observed after a conditioning activity. © 2016 National Strength and Conditioning Association

Postactivation potentiation of bench press throw performance using velocity-based conditioning protocols with low and moderate loads

This study examined the acute effects of the bench press exercise with low and moderate loads as well as with two predetermined movement velocity loss percentages on bench press throw performance and surface electromyographic (sEMG) activity. Ten trained men completed 5 main trials in randomized and counterbalanced order one week apart. Mean propulsive velocity (MPV), peak velocity (PV) and sEMG activity of prime movers were evaluated before and periodically for 12 minutes of recovery under five conditions: Using loads of 40 or 60% of 1 RM, until mean velocity dropped to 90 or 70%, as well as a control condition (CTRL). MPV and PV were increased 4-12 min into recovery by 4.5-6.8% only after the 60%1RM condition during which velocity dropped to 90% and total exercise volume was the lowest of all conditions (p < 0.01, Hedges' g = 0.8-1.7). When peak individual responses were calculated irrespective of time, MPV was increased by 9.2 ± 4.4 (p < 0.001, Hedges' g = 1.0) and 6.1 ± 3.6% (p < 0.001, Hedges' g = 0.7) under the two conditions with the lowest total exercise volume irrespective of the load, i.e. under the conditions of 40 and 60% 1RM where velocity was allowed to drop to 90%. sEMG activity of the triceps was significantly greater when peak individual responses were taken into account only under the 60%1RM condition when velocity dropped to 90% (p < 0.05, Hedges' g = 0.4). This study showed that potentiation may be maximized by taking into account individual fatigue profiles using velocity-based training. © 2019 Athanasios Tsoukos, Lee E. Brown, Panagiotis Veligekas, Gerasimos Terzis, Gregory C. Bogdanis, published by Sciendo

Elite high jumpers exhibit inadequate nutrient intakes

High jumpers strive to maintain low body mass and may be at increased risk for inadequate nutrient intakes. Since there is no data on the nutritional status in this sport, this study aimed to evaluate the nutritional intake of elite high jumpers (7 males, 7 females). Athletes were in energy balance (energy intake was equal to energy expenditure and body mass was stable), but their energy intake was among the lowest reported for athletes (148±23 and 142±18 kJ/kg/day, for males and females). Carbohydrate intake of both males and females (3.6±0.8 g/kg/day) was low compared with recommended values, and diet was deficient in several micronutrients such as vitamin D (12% of dietary reference intake, DRI), vitamin E (34% DRI), folate (46% DRI), calcium (78% DRI) and iron (55% DRI, for females only). These low carbohydrate and micronutrient intakes may negatively affect training quality and adaptations and may jeopardize the athletes' health. © JPES

Delayed effects of a low-volume, power-type resistance exercise session on explosive performance

This study examined the delayed effects of a power-type training session on explosive performance. Seventeen well-trained male power and team sport athletes (age: 22.7 ± 5.5 years, height: 181 ± 8 cm, body mass: 80.7 ± 8. ± kg, body fat: 9.2 ± 1.7%, 1 repetition maximum (1RM) half-squat: 163 6 29 kg) performed 4 sessions (2 experimental and 2 control) 1 week apart in a randomized and counterbalanced order. Explosive performance was assessed before, 24 and 48 hours after a low-volume, power-type training session (5 3 4 jump squats at 40% 1RM with 3 minutes rest), as well as before and after 24 and 48 hours of rest (control). Dependent variables were as follows: countermovement jump (CMJ), reactive strength index (RSI) during a drop jump, leg press maximum isometric force, and rate of force development (RFD) at 3 time windows: 0–100, 0–200, and 0–300 milliseconds. Analysis of variance revealed no changes in the control conditions. In contrast after training, CMJ was improved by 5.1 ± 1.0% and 3.0 ± 1.0% at 24 and 48 hours, respectively, compared with baseline. The RSI improved by 10.7 ± 2.1% only at 24 hours. The RFD increased at all time windows at 24 hours (range of improvement: 9.7 ± 3.4% to 18.3 ± 4.1%, p< 0.01). However, at 48 hours, improvement was only seen in RFD0–100 (9.8 ± 3.1%, p < 0.01). These findings suggest that a low-volume, power-type training session results in delayed enhancement of explosive muscle performance, which is greatest at 24 hours after the activity. Athletes are advised to perform power-type training 1 day before competition or a high-quality training session to improve their performances. © 2017 National Strength and Conditioning Association

Upper and lower body power are strong predictors for selection of male junior National volleyball team players

The purpose of this study was to determine whether a battery of anthropometric and lower and upper body strength and speed and power tests predicted selection of young volleyball players for a Junior National Team by expert coaches. Fifty-two male junior volleyball players (14.8 6 0.5 years, height: 1.84 6 0.05 m, body mass: 72.5 6 7.1 kg) took part in a training camp and underwent a selection procedure by expert coaches' of the junior national team. Anthropometric data and fitness tests re- sults were obtained and players were graded on a scale from 0 to 100 on the basis of their performance in a volleyball tour- nament. Selected players were superior in the majority of mea- sured variables (p # 0.017) and had higher grading scores compared with nonselected players (85.3 6 4.1 vs. 70.5 6 5.6, respectively, p , 0.01). The combination of spike jump and reach (SJR) test and 3-kg medicine ball throw (MB3) veloc- ity explained 63.5% of the variance in expert coaches' grading (p , 0.001). A multivariate discriminant analysis yielded a signifi- cant discriminant function (Wilk's lambda = 0.55, x2 = 29.324, p , 0.001, h2 = 0.82). Spike jump and reach and MB3 were the only variables that contributed to the discriminant function (stan- dardized function coefficients: SJR = 0.68, MB3 = 0.67). Cross- validation results showed that selection was correctly predicted in 14 of the 16 selected players (predictive accuracy: 87.5%) and in 32 of the 36 nonselected players (predictive accuracy: 88.9%). The SJR and MB3 fitness tests can predict a large portion of the variance of expert coaches' grading and successfully discriminate elite young male volleyball players for selection vs. nonselection for a junior national team. This result is very important as performance testing during a selection process may be reduced to only 2 measurements

Upper and Lower Body Power Are Strong Predictors for Selection of Male Junior National Volleyball Team Players

Tsoukos, A, Drikos, S, Brown, LE, Sotiropoulos, K, Veligekas, P, and Bogdanis, GC. Upper and lower body power are strong predictors for selection of male junior National volleyball team players. J Strength Cond Res 33(10): 2760-2767, 2019-The purpose of this study was to determine whether a battery of anthropometric and lower and upper body strength and speed and power tests predicted selection of young volleyball players for a Junior National Team by expert coaches. Fifty-two male junior volleyball players (14.8 ± 0.5 years, height: 1.84 ± 0.05 m, body mass: 72.5 ± 7.1 kg) took part in a training camp and underwent a selection procedure by expert coaches' of the junior national team. Anthropometric data and fitness tests results were obtained and players were graded on a scale from 0 to 100 on the basis of their performance in a volleyball tournament. Selected players were superior in the majority of measured variables (p ≤ 0.017) and had higher grading scores compared with nonselected players (85.3 ± 4.1 vs. 70.5 ± 5.6, respectively, p < 0.01). The combination of spike jump and reach (SJR) test and 3-kg medicine ball throw (MB3) velocity explained 63.5% of the variance in expert coaches' grading (p < 0.001). A multivariate discriminant analysis yielded a significant discriminant function (Wilk's lambda = 0.55, χ = 29.324, p < 0.001, η = 0.82). Spike jump and reach and MB3 were the only variables that contributed to the discriminant function (standardized function coefficients: SJR = 0.68, MB3 = 0.67). Cross-validation results showed that selection was correctly predicted in 14 of the 16 selected players (predictive accuracy: 87.5%) and in 32 of the 36 nonselected players (predictive accuracy: 88.9%). The SJR and MB3 fitness tests can predict a large portion of the variance of expert coaches' grading and successfully discriminate elite young male volleyball players for selection vs. nonselection for a junior national team. This result is very important as performance testing during a selection process may be reduced to only 2 measurements

Muscle Fiber and Performance Changes after Fast Eccentric Complex Training

Introduction The purpose of this study was to examine the effects of a short-term fast eccentric and ballistic complex training program on muscle power, rate of force development (RFD), muscle fiber composition, and cross-sectional area (CSA). Methods Sixteen male physical education students were randomly assigned to either a training group (TG, n = 8) or a control group (n = 8). The TG followed a 6-wk low volume training program, including fast eccentric squat training with an individually optimized load of 74% ± 7% of maximal half-squat strength (1RM) twice per week and a ballistic training session with loaded (30% 1RM) and unloaded jump squats, once per week, all combined with unloaded plyometric jumps. Results Half squat 1RM was increased in the TG from 1.87 ± 0.28 to 2.14 ± 0.31 kg per kilogram body mass (14.4% ± 9.3%, P = 0.01). The percentage of types I, IIA, and IIX fibers were similar in the two groups at pretesting and did not change after the intervention period (P = 0.53-0.89). Muscle fiber CSA increased in all fiber types by 8.3% to 11.6% (P = 0.02 to 0.001) in TG only. Countermovement jump height and peak power measured at five different external loads (0%-65% of 1RM) only increased in the TG by approximately 20% to 36% (P < 0.01) and approximately 16% to 22% (P < 0.01), respectively. Peak ground reaction force during jump squats remained unchanged in both groups, whereas RFD increased in the TG only (40%-107%, P = 0.001). Conclusions A combination of low-volume fast eccentric and ballistic jump squat training with plyometric jumps in a strength-power potentiation complex format, induced substantial increases in peak leg muscle power, RFD, and maximal strength, accompanied by gains in CSA of all muscle fiber types, without a reduction in fast twitch fiber composition. © 2018 Lippincott Williams and Wilkins. All rights reserved