Petronijevic, MS, Garcia Ramos, A, Mirkov, DM, Jaric, S, Valdevit, Z, and Knezevic, OM. Self-preferred initial position could be a viable alternative to the standard squat jump testing procedure. J Strength Cond Res 32(11): 3267–3275, 2018—The purpose of this study was to compare both the magnitude and reliability of different variables (knee angle, squat depth, jump height [Hmax], maximum force [Fmax], and maximum power [Pmax]) between the standardized squat jump (SJ) and the SJ performed from the self-preferred position. Eleven team handball players (age: 19.5 ± 1.1 years; height: 1.88 ± 0.06 m; and body mass: 82.1 ± 8.7 kg) and 13 physically active students (age: 20.5 ± 0.9 years; height: 1.81 ± 0.06 m; and body mass: 76.6 ± 6.6 kg) were evaluated on 2 sessions during the standardized SJ (knee angle fixed at 90°) and the self-preferred SJ (self-selected knee angle to maximize Hmax). Two blocks of both 3 standardized SJ and 3 self-preferred SJ were performed on the first session, whereas only 1 block was performed in the second session. The squat depth was smaller for the self-preferred SJ, whereas the knee angle, Fmax, and Pmax were higher for the self-preferred SJ (p < 0.025). The magnitude of Hmax did not significantly differ between both jump types. Most importantly, the reliability of the mechanical outputs (Hmax, Fmax, and Pmax) was generally higher for the self-preferred SJ (9 of 12 comparisons), whereas only in 2 of 12 comparisons the reliability was meaningfully higher for the standardized SJ. No differences were observed between presumably more (handball players) and less skilled individuals (physically active subjects). These results suggest that the self-preferred SJ should be recommended over the standardized SJ (90° knee angle) because it is not only quicker and more ecologically valid, but could also provide the performance variables with higher reliability.

The purposes of this study were to determine: 1) morning-to-evening differences in physical performance with and without a ball; and 2) associations between sleep outcomes (duration and quality) and physical performance in handball players. Sixteen elite, male handball players (25.4 ± 5.8 yr, 94.0 ± 7.4 kg, 193.5 ± 7.5 cm) completed physical performance tests without a ball (a zig-zag test assessing closed-skill agility, linear sprints, and countermovement (CMJ) and squat jumps) and with a ball (a zig-zag test and linear sprints) in the morning and evening. In addition, sleep quality and quantity during the night before testing were obtained using self-reported measures. Superior physical performance was evident in all tests during the evening compared to the morning hours (p < 0.003). Specifically, jump height was moderately (effect size (ES) = 0.73 to 1.02) higher during the evening. Similarly, moderate (ES = 1.17) and large (ES = 1.67) improvements in zig-zag test performance were apparent during the evening with and without the ball, respectively. Also, large to very large (ES = 1.29 to 2.09) increases in sprint performance with and without the ball were evident in the evening. No significant correlations (p > 0.05) were apparent between sleep duration and quality and physical performance in both the morning and evening sessions. Diurnal variations in physical performance were apparent in elite male handball players with enhanced performance with and without the ball in the evening compared to morning hours. These findings indicate that morning-to-evening differences in physical performance should be considered when developing conditioning plans or preparing for competition in handball.

This paper aims to define differences in Simple Visual Reaction Time (SVRT) and Reaction Time Variation (RTV), related to age and player position in Serbian female cadet and junior national handball team members. The method used in this research was laboratory testing. All data sampling was performed using specially designed testing software that recorded visual reaction time with 1 ms precision. SVRT was expressed in ms, and RTV was expressed as a coefficient of variation percentage value. The overall sample consisted of 34 players - 19 cadets and 15 juniors. Mean SVRT of 194.28±16.55 and 184.73±16.68 ms was determined in the subsamples of cadet and junior players, respectively. It was found that cadets have a mean RTV of 4.74±2.41% while juniors have a mean RTV of 7.90±3.70%. Results of the Factorial ANOVA have shown that there are no general, statistically significant, differences in SVRT in relation to age, player position, and interaction of these factors (p>0.05). Statistically significant difference in RTV on a general level was found in relation to age (F=9.752, p=0.005), while differences in relation to player position or combination of these factors were not statistically significant (p>0.05). Post hoc tests have shown partial differences in relation to player position. The method of mathematical modelling was used to define the statistical model of performance in relation to the given variables. The final form of the model explained 100% of the measured variance (AdjR2 = 1.000), which implies its absolute predictive potential considering the characteristics of the sample.

BackgroundIntensive exercise changes physiological need for glucose and several biochemical pathways responsible for its metabolism response. Among them are those which involve insulin, insulin-like growth factor (IGF-1), and IGF-binding proteins (IGFBPs). Different types and degrees of exercise, as well as an athlete's fitness, may induce a range of responses regarding concentrations and time needed for the alteration. The idea of the work was to find out whether and how insulin/IGF axis responds to additional physical activity in the already trained subjects and if so, is the adaptation potentially beneficial from the aspect of metabolic control.MethodsThe effect of 4-week intensive training on campus (preparatory training) on the levels of insulin, IGF-1, and IGFBPs during maximal progressive exercise test (MPET) on a treadmill was compared to the results obtained during MPET conducted after a regular training season of a female elite handball team (n = 17, age: 17 ± 1 years, height: 171 ± 8 cm, weight: 65 ± 8 kg, body mass index: 22 ± 1 kg/m2 at the beginning of the study; there were no significant changes at the end). Serum samples were obtained from players immediately before the test (basal), at the end of the test after reaching the point of maximal oxygen consumption (VO2max), and after recovery.ResultsThe concentration of insulin decreased at VO2max, but remained higher in players after preparatory training (12.2 ± 2.5 mU/L vs. 8.9 ± 4.4 mU/L, p = 0.049). The level of IGFBP-1 decreased in players at VO2max in either case of training, but it remained much higher in tests performed after the preparatory regime than before (p = 0.029). Concentrations of IGF-1, IGFBP-2, -3, and -4 did not change significantly.ConclusionThe inverse relation between insulin and IGFBP-1 was lost during MPET, as these 2 molecules changed in the same direction. The results obtained suggest less severe stress-induced depression of insulin and IGFBP-1 after preparatory training. But another metabolic mechanism cannot be excluded, and that is potentially impaired insulin sensitivity resulting in higher level of IGFBP-1.

The aim of this work is to present and analyse the handball literature on the causes of injuries, types of injuries and their anatomic locations, as well as the prevention measurements. Based on the results of the analysed studies, it can be concluded that there is a significant number of injuries, of different body parts and of different severity in top-level handball players. Overuse injuries (to certain body parts, such as the more dominant shoulder, the ankle and the knee) are considered to be most prominent. In order to prevent the injuries to the mouth and teeth, the use of mouthguard is recommended. When it comes to the prevention and rehabilitation of shoulder injuries, the research results have shown positive effects that the training aiming at the increase of the inner rotation of the glenohumeral strength, the outer rotation strength and the scapular muscles strength has along with the exercises for improving the kinetic chain and the chest flexibility. The use of elastic bands and the medicine ball has proven efficient in increasing the shoulder area strength, and the whole swing and throw movement. The ankle and the knee are the most frequently injured joints among female handball players. The results of the application of the neuromuscular training, the proprioception and the balance exercises, combined with some specific players’ activities (running, jumping and planting) show that such training process is efficient in the prevention of injuries to ankle and knee joints.