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Background: An increase in training intensity could create changes in psychological and physiological variables in competitive athletes. For this reason, it is very relevant to know how an intensive training block could influence psychological variables in competitive swimmers. This study examined the effect of an intensive training block (HIT) for 2 weeks on the anxiety state and swimming performance compared to standard aerobic training., Methods: Twenty-two male competition swimmers were randomly assigned to two groups: HIT group ( n = 11; age = 16.5 ± 0.29 years) and control group following the standard training program ( n = 11; age = 16.1 ± 0.33 years). Psychological status variables (cognitive anxiety, somatic anxiety and self-confidence) and swimming performance (100-m front crawl) were measured pre-and post-test., Results: A significant effect of time was found for all psychological variables and swimming performance (F ≥ 17.6; p < 0.001; d ≥ 0.97). Furthermore, a significant group × time interaction effect was found in cognitive (F = 14.9; p < 0.001; d = 0.62) and somatic anxiety (F = 5.37; p = 0.031; d = 0.55) were found. Only a significant group effect was found in somatic anxiety (F = 27.1; p < 0.001; d = 1.2). Post hoc comparison revealed that both groups increased their cognitive anxiety and swimming performance, and decreased their self-confidence from pre to post test. However, cognitive anxiety increase significantly more in the HIT group compared to the control group. Furthermore, only the HIT training group significantly increased somatic anxiety over time, while somatic anxiety did not change significantly over time in the control group., Conclusion: Our findings indicated that a sudden increase in training intensity increased state anxiety more than standard training, but both conditions similarly enhanced swimming performance. Although the current level of psychological state is not affecting swimming performance negatively over this period, it should be regularly monitored by psychologists as it over a longer training period perhaps could have a negative influence on swimming performance., Competing Interests: Tiago M. Barbosa is an Academic Editor for PeerJ., (© 2024 Aouani et al.)

Producing comparable/greater ground reaction forces (GRFs) at faster running speeds is beneficial for sprint performance, and assisted sprint training is used to induce faster running speed conditions. This study aimed to demonstrate the characteristics of assisted sprinting at the maximal speed phase and investigate acute differences to control sprinting. Fifteen sprinters completed control and assisted (5 kg) sprints over force platforms. Assisted sprinting increased running speed (9.3% mean difference), while propulsive mean force (-4.3%) and impulse (-12.4%) decreased, suggesting that running speed improvements were caused primarily by assisted pulling force rather than improvements in anteroposterior force production of athletes. In addition, vertical mean force increased (4.2%), probably due to braking mean force (34.2%) and impulse (32.5%) increases. Magnitude of control trial maximum speed was achieved earlier (during acceleration) in assisted trials, and net anteroposterior (includes both braking and propulsive components) mean force (67.2%) and impulse (67.9%) increased at this matched speed, suggesting that assisted sprints could be used to practice producing greater GRFs at comparable speeds. Running speed improvement by pulling force was associated with contact time decreases ( r  = -.565), suggesting that shortening contact time may be important for effective assisted sprinting.

Background: Sprint performance in junior Australian football (AF) players has been shown to be a differentiating quality in ability level therefore developing sprint characteristics via sprint-specific training methods is an important aspect of their physical development. Assisted sprint training is one training method used to enhance sprint performance yet limited information exists on its effect on sprint force-velocity characteristics. Therefore, the main aim of this study was to determine the influence of a combined sprint training intervention using assisted and maximal sprint training methods on mechanical characteristics and sprint performance in junior Australian football players., Methods: Upon completing familiarization and pre-testing, twenty-two male junior Australian football (AF) players (age 14.4 ± 0.3 years, body mass 58.5 ± 10.0 kg, and height 1.74 ± 0.08 m) were divided into a combined sprint training (CST) group (n = 14), and a maximal sprint training (MST) group (n = 8) based on initial sprint performance over 20-meters. Sprint performance was assessed during maximal 20-meter sprint efforts via a radar gun (36 Hz), with velocity-time data used to derive force-velocity characteristics and split times. All subjects then completed a 7-week in-season training intervention consisting of maximal sprinting (MST & CST groups) and assisted sprinting (CST only), along with their usual football specific exercises., Results: Moderate to large pre-post within group effects (-0.65 ≤ ES ≥ 0.82. p  ≤ 0.01) in the CST group for relative theoretical maximal force (F 0 ) and power (P max ) were reflected in improved sprint performance from 0-20 m, thereby creating a more force-oriented F-v profile. The MST group displayed statistically significant pre-post differences in sprint performance between 10-20 m only (ES = 0.18, p  = 0.04). Moderate to high relative reliability was achieved across all sprint variables (ICC = 0.65-0.91), except for the force-velocity slope (S FV ) and decrement in ratio of forces (D RF ) which reported poor reliability (ICC = 0.41-0.44), while the CST group exceeded the pre-post minimal detectable change (MDC) in most sprint variables suggesting a 'true change' in performance across the intervention., Conclusion: It is concluded that implementing a short-term, combined sprint training intervention consisting of assisted and maximal sprint training methods may enhance sprint mechanical characteristics and sprint performance to 20-meters in junior AF players., Competing Interests: The authors declare there are no competing interests, (©2023 Hicks et al.)

Information about when to apply an appropriate eccentric hamstring strength training stimulus during long-term athlete development is essential for effective programming and improving balance performance. This study examined the effects of six-week eccentric hamstring training on dynamic balance performance in youth handball players of different maturity statuses (pre- or post-peak height velocity (PHV)). A randomized controlled design with 45 young male handball players (14.6 ± 0.3 years) from a local national handball club were randomly allocated to a 6 week, twice weekly eccentric hamstring training in two experimental groups: a pre-PHV (maturation offset: −2.13 ± 0.63, n = 10) and post-PHV (maturation offset: 0.79 ± 0.34, n = 12) group and two control groups: maturation offset: −2.09 ± 0.61, n = 10 and maturation offset: 0.55 ± 0.67, n = 13. Dynamic balance performance was evaluated by using the composite score during the lower quarter Y-balance test from pre- and post-intervention. A significant effect on balance scores was found from pre to post (F = 11.4; p = 0.002; η2p = 0.22), intervention (F = 5.4; p = 0.025; η2p = 0.12), and maturation (F = 369; p < 0.001; η2p = 0.9), but no significant interaction effects were found (F ≥ 3.3; p ≥ 0.077; η2p ≤ 0.07). Post hoc analysis revealed that the post-PHV group had a higher score than the pre-PHV group. Furthermore, that dynamic balance increased in the post-PHV group after intervention much more in the control post-PHV group. It was concluded that somatic maturation influences dynamic balance performance and that eccentric hamstring training results in greater improvement in balance performance in young male handball players for the post-pubertal group.

This study aimed to examine the effect of four weeks of aquatic high-volume training (HVT) on the psychological state (somatic, cognitive anxiety, and self-confidence) and sprint swimming performance (50 m front crawl) compared to the standard training program (moderate volume training) in competitive swimmers. Twenty-eight male competitive swimmers participated in this study and were randomly allocated into two groups: HVT group (n = 14; age = 16.4 ± 0.31 years) and control group that underwent the standard training program (n = 14; age = 16.1 ± 0.30 years). All psychological state variables and swimming performance were measured in pre and post-test. Our findings showed a significant increase in anxiety state (34.13% to 45.83%; ES = 3.26 to 3.38) and a significant decrease in self-confidence (18.43%; ES = 2.39) after four weeks of HVT, while all psychological state variables remained unchanged in the control group (p > 0.05). In addition, our results showed no significant enhancement in swimming performance in both groups (p > 0.05). The sudden increase in training mileage negatively affected the anxiety, decreasing the state of self-confidence of the participants. In addition, four weeks of high training volume are insufficient to improve swimming performance. To conclude, gradually increasing the volume of the training load may be an adequate solution to promote adaptation to the effort, thus maintaining the stability of the psychological state of swimmers. In addition, it is recommended to integrate a concurrent mental preparation program with high-volume training to monitor the psychological state of competitive swimmers.

The aim of the current study was to investigate the effect of six weeks of strength vs. plyometric training upon change of direction (COD) performance. A total of 21 young female handball players were randomly assigned to either a strength group: (n = 11, age: 17.5 ± 2.3 years, height: 1.69 ± 0.05 m, weight: 65.8 ± 5.9 kg) training bilateral, unilateral and later squats; or a plyometric training group (n = 10, age: 17.1 ± 2.4 years, height: 1.73 ± 0.07 m, weight: 67.1 ± 9.3 kg) training drop jumps, unilateral countermovement jumps and skate-jumps. Groups were assigned after being pair-matched based upon baseline COD performance. The training modalities were matched in training impulse. A force- (180°) and velocity-oriented (45°) COD of 20 m was used to measure changes in COD performance (10 m + COD + 10 m). Total time (s) to complete the COD test was defined as the performance variable. The level of significance was set at p < 0.05. The two-way ANOVA showed no group effect upon COD performance. A significant effect was only observed for the strength training group in the last 10 m and total 20 m of the force-oriented COD (F ≥ 5.51; p ≤ 0.04; η2 ≥ 0.36). Both groups improved performance in other strength- and power-related tests. It was concluded that only the strength training program was effective in developing force-oriented COD performance in the studied population, while the plyometric training program was not sufficient. Both training modalities are useful for improving performance in different strength and power tests in young female handball players.

Strength training using high and lower load such as contrast training (CST) seems to be beneficial as it addresses larger adaptive reserves in youth athletes. Therefore, the aim of this study was to investigate the effects of CST on dynamic balance (composite score during dynamic balance test (CS-YBT)), one repetition maximum lower-limb back squat (1RM), jumping performance (single-leg hop (SLH) or countermovement jump height (CMJ)), lower-limb asymmetry (predicted from the single-leg jump performance between two legs [ILA]) in elite youth male volleyball players. Thirty-one male youth volleyball players aged 14 years were randomly assigned to a CST group (n = 16) or a control group (n = 15). The tests were performed before and after 8 weeks of training. Significant group × time interactions was observed for CS-YBT [p < 0.001, ηp2 = 0.70], 1RM [p < 0.001, ηp2 = 0.95], SLH with right and left leg [p < 0.001, ηp2 = 0.69 and 0.51], CMJ [p < 0.001, ηp2 = 0.47]), whilst it was not notable in ILA [p < 0.294]. Post hoc tests showed that CST group demonstrated greater improvement in all of the dependent variables from medium to large effect size (for all p < 0.001). As a result, 8 weeks of CST twice a week can be an effective and efficient training along with volleyball training to improve skill-related fitness measures, except for lower-limb asymmetry in young volleyball players.

Purpose: To compare the effects of increased load of low- versus high-intensity endurance training on performance and physiological adaptations in well-trained endurance athletes., Methods: Following an 8-week preintervention period, 51 (36 men and 15 women) junior cross-country skiers and biathletes were randomly allocated into a low-intensity (LIG, n = 26) or high-intensity training group (HIG, n = 25) for an 8-week intervention period, load balanced using the overall training impulse score. Both groups performed an uphill running time trial and were assessed for laboratory performance and physiological profiling in treadmill running and roller-ski skating preintervention and postintervention., Results: Preintervention to postintervention changes in running time trial did not differ between groups (P = .44), with significant improvements in HIG (-2.3% [3.2%], P = .01) but not in LIG (-1.5% [2.9%], P = .20). There were no differences between groups in peak speed changes when incremental running and roller-ski skating to exhaustion (P = .30 and P = .20, respectively), with both modes being significantly improved in HIG (2.2% [3.1%] and 2.5% [3.4%], both P < .01) and in roller-ski skating for LIG (1.5% [2.4%], P < .01). There was a between-group difference in running maximal oxygen uptake changes (P = .04), tending to improve in HIG (3.0% [6.4%], P = .09) but not in LIG (-0.7% [4.6%], P = .25). Changes in roller-ski skating peak oxygen uptake differed between groups (P = .02), with significant improvements in HIG (3.6% [5.4%], P = .01) but not in LIG (-0.1% [0.17%], P = .62)., Conclusion: There was no significant difference in performance adaptations between increased load of low- versus high-intensity training in well-trained endurance athletes, although both methods improved performance. However, increased load of high-intensity training elicited better maximal oxygen uptake adaptations compared to increased load of low-intensity training.

This study aimed to compare the effectiveness of high, moderate, and low resistance training volume-load of maximum strength training on muscle strength and swimming performance in competitive swimmers. Thirty-three male swimmers were randomly allocated to high (age = 16.5 ± 0.30 years), moderate (age = 16.1 ± 0.32 years) and a low resistance training volume-load group (age = 15.9 ± 0.31). This study was carried out in mid-season (January to March). Pre and post strength (e.g., repetition maximum [1RM] leg extension and bench press tests), swimming (25, 50 m front-crawl), start (speed, time, distance) and turn (time of turn) performance tests were conducted. Our findings revealed a large main effect of time for 1RM bench press: d = 1.38; 1RM leg extension: d = 1.55, and for 25 (d = 1.12), and 50 m (d = 1.97) front-crawl, similarly for start and turn performance (d = 1.28-1.46). However, no significant Group × Time interactions were shown in all strength swimming performances, start and turn tests ( p > 0.05). In conclusion, low training loads have been shown to elicit the same results as moderate, and high training loads protocol. Therefore, this study shows evidence that the addition of low training volume-loads as a regular part of a maximal strength training regime will elicit improvements in strength and swimming performance.

Backward running (BR) and forward running (FR) are unique movements utilized by athletes in many sports. Importantly, this investigation provides further insights on BR and benchmarking against more commonly researched FR capacity. Twenty-one collegiate soccer players (age 20.0 ± 0.8 years, body mass 65.6 ± 7.7 kg, body height 1.70 ± 0.07 m) performed maximal effort BR and FR along 20 m of in-ground force platforms. Step kinematics and kinetics were compared between BR and FR over four relative acceleration phases (BR = steps 1-6, 7-12, 13-18 and 19-23; FR = steps 1-4, 5-8, 9-12, 13-15). The primary findings of this study were that BR speeds were 29% slower than FR ( p < 0.001), all step kinematics differed between BR and FR ( p < 0.01), except contact time from the second to fourth step phases ( p > 0.05), and most step kinetics were lower during BR ( p < 0.05), with the exceptions of peak vertical force ( p > 0.05). These findings indicate that lower running speeds over the acceleration phases of BR appear to be primarily due to lower horizontal ground reaction force application, resulting in shorter stride lengths and decreased flight times compared to FR.

This study compared the kinematics (step and joint) and muscle activity of unresisted and active resisted 30 m sprints with different loads (10-40% body mass) in experienced male and female sprinters. Step kinematics were measured using a laser gun and contact mat in 28 male and female participants during unresisted 30 m sprint, and sprints with 10-40% of body mass (BM) active resistance, while peak angular velocities of lower limb was measured, together with muscle activation of nine muscles. Increased resisted loads resulted in slower 30 m times, as a result of lower step velocity mainly caused by shorter step lengths and frequencies, flight times and longer contact times, with a greater effect on women than on men. These step kinematic differences, due to increasing load were accompanied with lower peak joint movements. However, gender differences were only found for peak plantar flexion with unresisted and 10% BM resisted sprints. Furthermore, increasing load decreased calf and hamstring muscles activity, while medial vastus activity increased. Based upon these findings, it was concluded that when introducing active resisted sprints, women should sprint with approximately 10% less active loads than men to have equal step and joint kinematics development over the sprint distance.

Abstract: van den Tillaar, R. Comparison of step-by-step kinematics of elite sprinters' unresisted and resisted 10-m sprints measured with Optojump or Musclelab. J Strength Cond Res 35(5): 1419-1424, 2021-The purpose of this study was to compare step-by-step kinematics of unresisted and resisted 10-m sprints measured with the Optojump or Musclelab on elite sprinters. Six subjects (age 30.0 ± 5.1 years, body mass 76.3 ± 5.3 kg, body height 1.79 ± 0.09 m, and 100-m personal best 10.51 ± 0.3 s) performed 2 unresisted and 2 sets of 2 resisted (10 and 20% of body mass) 30-m sprints in random order (6 sprints in total) in 1 session in which kinematics of the first 10 m were measured with the Optojump and Musclelab. The main finding was that there were no significant differences between the measurements made with the Optojump and Musclelab systems. In addition, it was possible to discriminate most kinematic variables per step of the first 10 m when different loads (10 and 20% of body mass) had to be pulled during the 30-m sprints. The variations in sprint times associated with changes in the resistance provided by the dynaSpeed were mainly caused by a decrease in step length as the resistance increased. It was concluded that the 2 systems are valid and could help coaches, researchers, and athletes by providing more detailed information about possible changes to kinematics during training and sprinting with different resistances., (Copyright © 2018 National Strength and Conditioning Association.)

Injuries in handball are common due to the repetitive demands of overhead throws at high velocities. Monitoring workload is crucial for understanding these demands and improving injury-prevention strategies. However, in handball, it is challenging to monitor throwing workload due to the difficulty of counting the number, intensity, and type of throws during training and competition. The aim of this study was to investigate if an inertial measurement unit (IMU) and machine learning (ML) techniques could be used to detect different types of team handball throws and predict ball velocity. Seventeen players performed several throws with different wind-up (circular and whip-like) and approach types (standing, running, and jumping) while wearing an IMU on their wrist. Ball velocity was measured using a radar gun. ML models predicted peak ball velocity with an error of 1.10 m/s and classified approach type and throw type with 80-87% accuracy. Using IMUs and ML models may offer a practical and automated method for quantifying throw counts and classifying the throw and approach types adopted by handball players.

The aim of the study was to examine the acute effect of different lower limb wearable resistance on placement (shank vs thigh) and various loads (1-5% of body mass) upon change of direction (COD) ability. Twelve male soccer players (age: 23.3 ± 2.5 years; height: 179.2 ± 7.4 cm; body mass: 78.3 ± 7.1 kg) performed a change of direction test with different additional loads fixed on either the shank or thigh. Measurement consisted of total time, 90° and 45° split times. large effects of the different wearable resistance placement (p<0.05) and load (p<0.001) were found for total and split change of direction time performance. Change of direction times were higher with shank loading compared with thigh loading. It was concluded that lower limb wearable resistance loading with different loads had an acute effect upon change of direction performance in male soccer players. Furthermore, that distal placement (shank vs thigh) with similar body mass load had a larger effect upon COD performance., Competing Interests: The authors have declared that no competing interests exist.

The change of direction (COD) ability is an important task-specific skill for success in team sports, dependent on both strength and reactive strength. The sprint approaching the COD and degrees of the turn are factors influencing the specificity of the COD. Thus, CODs have been suggested to be categorized as force- (> 90°) and velocity-dominant (< 90°) dependent on the degree of the turn. When training programmes fail to provide a significant increase in COD performance, it is often due to neglecting the task-specific demands of the COD. As such, 23 male football players volunteered to complete a randomized controlled trial, investigating the association of maximal strength and power performance with performance in a force- (180°) and velocity-dominant (45°) COD, with a 4 m and 20 m sprint approach. Three strength and three plyometric exercises, matched in movement patterns, were used. Muscle activity of the different conditions was also compared. The correlational analysis revealed that better performance in the plyometric tests were associated with less time to complete both force- and velocity-dominant CODs, supported by similarities in muscle activation. None of the performances in strength exercises correlated to COD performance, due to the slow contraction velocity of maximal lifts. It was concluded that plyometrics share more physical similarities with CODs than the strength exercises., Competing Interests: The authors have declared that no competing interests exist.

This investigation examined step-by-step kinematics of sprint running acceleration. Using a randomised counterbalanced approach, 37 female team handball players (age 17.8 ± 1.6 years, body mass 69.6 ± 9.1 kg, height 1.74 ± 0.06 m) performed resisted, assisted and unloaded 20-m sprints within a single session. 20-m sprint times and step velocity, as well as step length, step frequency, contact and flight times of each step were evaluated for each condition with a laser gun and an infrared mat. Almost all measured parameters were altered for each step under the resisted and assisted sprint conditions ( η 2  ≥ 0.28). The exception was step frequency, which did not differ between assisted and normal sprints. Contact time, flight time and step frequency at almost each step were different between 'fast' vs. 'slow' sub-groups ( η 2  ≥ 0.22). Nevertheless overall both groups responded similarly to the respective sprint conditions. No significant differences in step length were observed between groups for the respective condition. It is possible that continued exposure to assisted sprinting might allow the female team-sports players studied to adapt their coordination to the 'over-speed' condition and increase step frequency. It is notable that step-by-step kinematics in these sprints were easy to obtain using relatively inexpensive equipment with possibilities of direct feedback.

Background: This study assessed inter-relationships between shuttle and straight repeated-sprint ability tests and the relationship of each measure to anthropometric and explosive lower limb performance data in elite handball players., Methods: Twenty-two elite male handball players (18.9±0.2 years; body mass: 83.3±1.1 kg, height: 1.79±2.30 m, body fat: 12.8±0.2%) completed tests that included a lower limb force-velocity test of peak power (Wpeak), jumping ability (squat and counter-movement jumps; SJ, CMJ), 1 repetition maximum (1-RM) half back squat, average sprint velocity over 5 m (V-5 m), peak velocity between 25-30 m (Vmax), and Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1), and anthropometric determinations of cross-sectional areas and muscle volumes for leg and thigh muscles. Data were compared with performance on two repeated sprint tests; the straight test (6 × 30 m [RSA30]) and the intermittent test (6×[2×15 m] shuttle sprints [RSA15])., Results: V-5 m, 1-RM, and thigh and leg muscle cross-sectional areas and volumes showed relevant relationships to the shuttle RSA test (r2≥0.5). The Yo-Yo IR1 explained the largest percentage of variance in RSA15 total time (60%), and V-5 m also explained 56% of the variance in RSA15 total time. RSA15% fatigue was only related to 1-RM (explained variance: 58%), and the RSA30 test showed no useful correlations with any of the investigated predictors. Multiple-regression analyses using all physical tests explained 91% of the variance in RSA15 total time (P<0.001)., Conclusions: The volume of the leg muscles seems important to power production and repeated sprints over distances of 15 m or less. RSA15 is related to muscular power, maximal strength, speed and endurance performance; however, the straight repeated sprint ability test is not, and thus does not seem relevant for the testing of handball players.

van den Tillaar, R. Comparison of step-by-step kinematics in repeated 30-m sprints in female soccer players. J Strength Cond Res 32(7): 1923-1928, 2018-The aim of this study was to compare kinematics in repeated 30-m sprints in female soccer players. Seventeen subjects performed seven 30-m sprints every 30 seconds in one session. Kinematics was measured with an infrared contact mat and laser gun, and running times with an electronic timing device. The main findings were that sprint times increased in the repeated-sprint ability test. The main changes in kinematics during the repeated-sprint ability test were increased contact time and decreased step frequency, whereas no change in step length was observed. The step velocity increased in almost each step until the 14th, which occurred around 22 m. After this, the velocity was stable until the last step, when it decreased. This increase in step velocity was mainly caused by the increased step length and decreased contact times. It was concluded that the fatigue induced in repeated 30-m sprints in female soccer players resulted in decreased step frequency and increased contact time. Using this approach in combination with a laser gun and infrared mat for 30 m makes it very easy to analyze running kinematics in repeated sprints in training. This extra information gives the athlete, coach, and sports scientist the opportunity to give more detailed feedback and helps to target these changes in kinematics better to enhance repeated-sprint performance.

The aim of this study was to identify the influence of prior knowledge of exercise duration on players' pacing patterns during soccer small-sided games. Twenty semi-professional male soccer players participated in this study. In the first game scenario, players were not informed how long they would be required to play the small-sided game and the activity was terminated after 20 min (Unknown Condition). In the second game scenario, players were told that they would play the small-sided game for 10 min, but immediately after completing the 10-min game, they were asked to complete another 10 min (Partially Condition). In the third game scenario, players were instructed that they would play the small-sided game for 20 min and then they completed the 20-min game (Known Condition). The results presented a tendency of higher values in all performance variables in the [0'-10'] min compared with the [10'-20'] min. As the players' previous knowledge about the tasks duration increased, the performance between two moments tended to be similar. Considering the entire 20-min game duration, the Partially Condition of the exercise was the most demanding condition. In conclusion, the knowledge of shorter durations of the exercise seems to lead to an increase of exercise duration demand, and longer exercise durations possibly tend to decrease differences between full knowledge and not knowing the exercise duration.

The authors' purpose was to investigate if there is a speed accuracy trade-off in soccer kicking by using instructions prioritizing velocity, accuracy, or both upon soccer kicking performance and kicking direction in experienced soccer players. In addition, kinematics were measured to investigate the eventual differences in performance. Thirteen experienced male footballers performed penalty kicks with different instructions prioritizing velocity, accuracy or both. Three-dimensional kinematics, together with maximal ball velocity and hitting accuracy, were measured on all kicks. The main findings were that when the main aim was accuracy, accuracy increased, while the velocity reduced, which supports Fitts' law (Fitts, 1954 ). In addition, kicking accuracy was higher when kicking to the contralateral side. The slower ball velocity was caused by lower segmental and in run velocities. These lower segmental velocities were mainly caused by the lower maximal knee extension and pelvis rotation during the accuracy priority kicks.

van den Tillaar, R, Vatten, T, and von Heimburg, E. Effects of short or long warm-up on intermediate running performance. J Strength Cond Res 31(1): 37-44, 2017-The aim of the study was to compare the effects of a long warm-up (general + specific) and a short warm-up (specific) on intermediate running performance (3-minute run). Thirteen experienced endurance-trained athletes (age 23.2 ± 2.3 years, body mass 79.8 ± 8.2 kg, body height 1.82 ± 0.05 m) conducted 2 types of warm-ups in a crossover design with 1 week in between: a long warm-up (10 minutes, 80% maximal heart rate, and 8 × 60 m sprint with increasing intensity and 1 minute rest in between) and a short warm-up (8 × 60 m sprint with increasing intensity and 1 minute rest in between). Each warm-up was followed by a 3-minute running test on a nonmotorized treadmill. Total running distance, running velocity at each 30 seconds, heart rate, blood lactate concentration, oxygen uptake, and rate of perceived exertion were measured. No significant differences in running performance variables and physiological parameters were found between the 2 warm-up protocols, except for the rate of perceived exertion and heart rate, which were higher after the long warm-up and after the 3-minute running test compared with the short warm-up. It was concluded that a short warm-up is as effective as a long warm-up for intermediate performance. Therefore, athletes can choose for themselves if they want to include a general part in their warm-up routines, even though it would not enhance their running performance more compared with only using a short, specific warm-up. However, to increase efficiency of time for training or competition, these short, specific warm-ups should be performed instead of long warm-ups.

van den Tillaar, R and von Heimburg, E. Comparison of two types of warm-up upon repeated-sprint performance in experienced soccer players. J Strength Cond Res 30(8): 2258-2265, 2016-The aim of the study was to compare the effects of a long warm-up and a short warm-up upon repeated-sprint performance in soccer players. Ten male soccer players (age, 21.9 ± 1.9 years; body mass, 77.7 ± 8.3 kg; body height, 1.85 ± 0.03 m) conducted 2 types of warm-ups with 1 week in between: a long warm-up (20 minutes: LWup) and a short warm-up (10 minutes: SWup). Each warm-up was followed by a repeated-sprint test consisting of 8 × 30 m sprints with a new start every 30th second. The best sprint time, total sprinting time, and % decrease in time together with heart rate, lactate, and rate of perceived exertion (RPE) were measured. No significant differences in performance were found for the repeated-sprint test parameters (total sprint time: 35.99 ± 1.32 seconds [LWup] and 36.12 ± 0.96 seconds [SWup]; best sprint time: 4.32 ± 0.13 seconds [LWup] and 4.30 ± 0.10 seconds [SWup]; and % sprint decrease: 4.16 ± 2.15% [LWup] and 5.02 ± 2.07% [SWup]). No differences in lactate concentration after the warm-up and after the repeated-sprint test were found. However, RPE and heart rate were significantly higher after the long warm-up and the repeated-sprint test compared with the short warm-up. It was concluded that a short warm-up is as effective as a long warm-up for repeated sprints in soccer. Therefore, in regular training, less warm-up time is needed; the extra time could be used for important soccer skill training.

The purpose of this study was to compare the effect of a specific resistance training program (throwing movement with a medicine ball) with that of regular training (throwing with regular balls) on ball velocity, anthropometry, maximal upper-body strength, and power. Thirty-four elite male team handball players (age: 18 ± 0.5 years, body mass: 80.6 ± 5.5 kg, height: 1.80 ± 5.1 m, body fat: 13.4 ± 0.6%) were randomly assigned to 1 of the 3 groups: control (n = 10), resistance training group (n = 12), or regular throwing training group (n = 12). Over the 8-week in season, the athletes performed 3 times per week according to an assigned training program alongside their normal team handball training. One repetition maximum (1RM) bench press and 1RM pullover scores assessed maximal arm strength. Anthropometry was assessed by body mass, fat percentage, and muscle volumes of upper body. Handball throwing velocity was measured by a standing throw, a throw with run, and a jump throw. Power was measured by measuring total distance thrown by a 3-kg medicine ball overhead throw. Throwing ball velocity, maximal strength, power, and muscle volume increases for the specific resistance training group after the 8 weeks of training, whereas only maximal strength, muscle volume and power and in the jump throw increases were found for the regular throwing training group. No significant changes for the control group were found. The current findings suggest that elite male handball players can improve ball velocity, anthropometrics, maximal upper-body strength, and power during the competition season by implementing a medicine ball throwing program.

The authors' aim was to investigate the speed-accuracy tradeoff in soccer kicking with the dominant and nondominant foot by using different types of instructions prioritizing speed or accuracy in experienced soccer players. Ten male soccer players were randomly given 1 of the 4 instructions that differed in aspects of the kick they should emphasize and what the secondary aim would be (speed or accuracy). It was found that ball velocity was affected by instruction in the expected way: emphasis on accuracy and ball velocity reduced for both kicking feet. In addition kicking accuracy increased when emphasizing this, but only with the dominant foot indicating that Fitts' law only was found in kicks with the dominant foot.

This study compared the effect of practice throwing with specific weights (specificity principle) or with variable weights (variability of practice) for a short practice period in children. Primary school children (N = 41; M age = 7.7 yr., SD = 0.5) were randomly divided into three homogenous groups. The first two groups used specific overhead throwing practice: throws with a soccer ball or 1 kg balls, while the third group used variable practice with 0.35, 0.45, 0.5, and 1 kg balls. All groups trained twice per week for six weeks. The same workload per session between the three groups varied from 24 throws (1 kg practice group) to 43 throws (soccer ball practice group). Throwing speed and distance with different balls was measured before and after the practice period. Statistically significant increases in performance in all three practice groups were found with no significant differences between groups. The results indicate that both specific and variable practice of throwing in children lead to increases in performance. However, it seems that the increased workload (practice) is a more important factor than the type of practice (specific or variable) in enhancing performance in children.

The aim of this study was to test the reliability of throwing velocity in a seated chest throw action and in a standing overhead situation with 3 differently weighted medicine balls using a Doppler radar gun. To test the reliability of throwing velocity of the 2 different techniques and various weights, a repeated measurement setup was used. Seventy-nine (55 men and 23 women) college sport science students performed standing overhead throws and seated chest throws with medicine balls weighted 1, 3, and 5 kg. A systematic bias was found (p < 0.001) in overhead throwing but not in seated chest throwing. Furthermore, the variability of maximal throwing velocity decreased with increasing ball weights and was much higher in standing throws compared with that in the seated chest throws. The retest correlations (intraclass correlation coefficients) were high in all throwing tests, varying from 0.88 to 0.96. It was concluded that measuring throwing velocity using the Doppler radar gun in standing overhead throws and seated chest throws with different weights shows high reliability. However, reliability is affected by throwing weight and throwing technique, which can be of relevance when conducting studies and testing training effects with these parameters.

The purpose of this study was to investigate the effect of a single and a double training workload with 3-kg medicine ball on the throwing speed in 2-handed overhead throwing movement. Second, what the effect of training with 3-kg medicine balls had on throwing speed with other ball weights. Forty high school students (age 15.9 ± 1.0 year, mass 60.9 ± 9 kg, height 1.68 ± 0.08 m), divided into 3 speed-matched groups, participated in the study. The first group was a control group and did not train any throwing program regimen, whereas the other 2 groups trained overhead throwing with a single (3 series of 6 throws with a 3-kg medicine ball) or double training workload (6 series of 6 throws with a 3-kg medicine ball) for 6 weeks. Throwing speed with 0.35-, 0.45-, 1-, and 3-kg medicine balls was tested before and after a training period of 6 weeks with 2 sessions per week. A significant (p ≤ 0.05) increase in throwing speed was found after the 6-week training period with the 0.35- (5.1%), 1- (3.5%), and 3-kg medicine balls (5.2%) for both training groups, but not with the 0.45-kg ball (0.6%). This increase was mainly caused by the increase of the double workload group. This indicates that training workload is of importance in these subjects for enhancement of ball throwing performance and in designing training programs. Furthermore, that throwing with high enough training volume of throws with a 3-kg medicine ball also can increase ball speed with lighter balls.

The aim of this study was to investigate the throwing velocity and kinematics of overarm throwing in team handball of elite female and male handball players. Kinematics and ball velocity of a 7 metre-throw in eleven elite male (age 23.6 ± 5.2 yr, body mass 87.0 ± 6.8 kg, height 1.85 ± 0.05 m) and eleven elite female (age 20.3 ± 1.8 yr, body mass 69.9 ± 5.5 kg, height 1.75 ± 0.05 m) team handball players were recorded. The analysis consisted of maximal joint angles, angles at ball release, maximal angular velocities of the joint movements, and maximal linear velocities of the distal endpoints of segments and their timing during the throw. The ball release velocity of the male handball players was significantly higher than the females (21.1 vs. 19.2 m · s(-1); p < 0.05). No major differences in kinematics were found, except for the maximal endpoint velocities of the hand and wrist segment, indicating that male and female handball players throw with the same technique. It was concluded that differences in throwing velocity in elite male and female handball players are generally not the result of changes in kinematics in the joint movements.

The purposes of this study were to examine the activity profile of elite adolescent players during regular team handball games and to compare the physical and motor performance of players between the first and second halves of a match. Activity patterns (video analysis) and heart-rate (HR) responses (telemetry) were monitored in top national-division adolescent players (18 men, aged 15.1 ± 0.6 years) throughout 6 regulation games (25-minute halves with a 10-minute interval). The total distance covered averaged 1,777 ± 264 m per game (7.4% less in the second than in the first half, p > 0.05). Players ran 170 ± 24 m at high intensity and 86 ± 12 m at maximal speed, with 32 ± 6 bouts of running (duration 2.3 ± 0.3 seconds) at speeds > 18 km·h(-1); they stood still for 16% of the playing time. The mean HR during play was 172 ± 2 b·min(-1) (82 ± 3% of maximal HR). Blood lactate concentrations at the end of the first and second halves were 9.7 ± 1.1 and 8.3 ± 0.9 mmol·L(-1), respectively (difference p < 0.05). We conclude that adolescent handball players cover less distance and engage in fewer technical actions in the second half of a match. This indicates that team handball is physiologically very demanding. The practical implication is that coaches should seek to sustain performance in the second period of a game by modifying playing tactics and maximizing both aerobic and anaerobic fitness during training sessions.

The aim of this study was to compare the kinematics in throwing with a regular weighted handball with 20% lighter and heavier balls in female experienced handball players. In total, eight joint movements during the throw were analyzed. The analysis consisted of maximal angles, angles at ball release, and maximal angular velocities of the joint movements and their timings during the throw. Results on 24 experienced female team handball players (mean age 18.2 ± 2.1 years) showed that the difference in ball weight affected the maximal ball velocity. The difference in ball release velocity was probably a result of the significant differences in kinematics of the major contributors to overarm throwing: elbow extension and internal rotation of the shoulder. These were altered when changing the ball weight, which resulted in differences in ball release velocity.

The purpose was to study the effect of a sling exercise training (SET)-based core stability program on maximal throwing velocity among female handball players. Twenty-four female high-school handball players (16.6 ± 0.3 years, 63 ± 6 kg, and 169 ± 7 cm) participated and were initially divided into a SET training group (n = 14) and a control group (CON, n = 10). Both groups performed their regular handball training for 6 weeks. In addition, twice a week, the SET group performed a progressive core stability-training program consisting of 6 unstable closed kinetic chain exercises. Maximal throwing velocity was measured before and after the training period using photocells. Maximal throwing velocity significantly increased 4.9% from 17.9 ± 0.5 to 18.8 ± 0.4 m·s in the SET group after the training period (p < 0.01), but was unchanged in the control group (17.1 ± 0.4 vs. 16.9 ± 0.4 m·s). These results suggest that core stability training using unstable, closed kinetic chain movements can significantly improve maximal throwing velocity. A stronger and more stable lumbopelvic-hip complex may contribute to higher rotational velocity in multisegmental movements. Strength coaches can incorporate exercises exposing the joints for destabilization force during training in closed kinetic chain exercises. This may encourage an effective neuromuscular pattern and increase force production and can improve a highly specific performance task such as throwing.

Purpose: The purpose of this study was to determine whether two throwing programs, based upon velocity or resistance with the same workload, would enhance soccer overhead throwing velocity., Methods: Sports science students (n = 64, age 21.1 +/- 2.1 y, mass 71.1 +/- 11 kg, height 1.75 +/- 0.09 m; mean +/- SD) divided into two groups matched on performance, participated in the study. The resistance-training group trained overhead throwing with a 5-kg medicine ball for two sets of 8 reps per session, whereas a velocity training group threw four sets of 16 reps with a regular soccer ball. These training programs were matched on workload. Throwing performance with a soccer ball and a 5-kg medicine ball were tested before and after a training period of 6 wk with two sessions per week., Results: Both groups significantly increased the throwing velocity with the soccer ball (resistance-training group: 3.2% [1.0-5.5%]; P = .003 and velocity-training group: 5.1% [2.6-7.7%]; P < .001), whereas no substantial changes were found for throwing with the 5-kg medicine ball after the training period. No substantial differences between the groups were found, which indicates that both forms of training increased the throwing velocity., Conclusions: It is concluded that both velocity and resistance throwing training programs after a short period of training with the same workload can increase throwing velocity and that workload is of importance in designing training programs and comparing them with each other.

Purpose: The main purpose of this study was to compare the effect of a specific resistance training program (throwing movement with a pulley device) with the effect of regular training (throwing with regular balls) on overarm throwing velocity under various conditions., Methods: The training forms were matched for total training load, ie, impulse generated on the ball or pulley device. Both training groups (resistance training n = 7 and regular training n = 6) consisted of women team handball players, and trained 3 times per week for 8 weeks, according to an assigned training program alongside their normal handball training., Results: An increase in throwing velocity with normal balls after the training period was observed for both groups (P = .014), as well as throwing with heavier balls and throwing like actions in the pulley device. Although the regular training group seemed to improve more (6.1%) in throwing velocity with normal balls than the resistance training group (1.4%), this difference was not statistically significant., Conclusions: These findings indicate that resistance training does not surpass standard throwing training in improvement of overarm throwing velocity.