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Gil, MH, Neiva, HP, Alves, AR, Sousa, AC, Ferraz, R, Marques, MC, and Marinho, DA. The effect of warm-up running technique on sprint performance. J Strength Cond Res XX(X) 000-000, 2020-The purpose of the current study was to analyze the effect of changing the running technique during warm-up on sprint performances, running biomechanics, physiological, and psychophysiological responses. Thirty-one physically active men aged 18-23 years (mean ± SD 19.35 ± 1.08 years of age; 1.77 ± 0.07 m of height; 71.90 ± 10.37 kg of body mass) volunteered to participate and randomly performed 2 maximal 30-m sprints, 5 minutes after completing a warm-up focused on increased stride length-SL (WUL) or a warm-up focused on increased stride frequency-SF (WUF). The results showed that there were no differences between the 30-m sprint performances and in running biomechanics. However, WUF showed increased performances in the first 15 m of the race (WUF 2.59 ± 0.11 seconds vs. WUL 2.63 ± 0.15 seconds; p = 0.03), and WUL resulted in higher performances in the last 15 m (1.94 ± 0.19 seconds vs. 1.88 ± 0.09 seconds; p = 0.05). In the second 30-m time trial, WUF also resulted in faster starting 15 m of the race (2.58 ± 0.12 seconds vs. 2.63 ± 0.16 seconds; p = 0.04). Interestingly, the WUF was the warm-up that revealed more stability in performances and running biomechanics between both trials. These results showed that there were no significant differences between warm-ups comprising exercises focusing in higher SL or higher SF in 30-m sprint biomechanics and performance. Nevertheless, different running strategies were caused by those 2 warm-ups and a more stabilized running pattern, and performance values were found when warm-up focused on higher SF.Tornero-Aguilera, JF, Fernandez-Elias, VE, and Clemente-Suárez, VJ. Ready for combat, psychophysiological modifications in a close-quarter combat intervention after an experimental operative HIIT. J Strength Cond Res XX(X) 000-000, 2019-This study aimed to analyze the effect of an experimental operative high-intensity interval training (HIIT) program on the psychophysiological response of soldiers in a close-quarter combat (CQC) intervention. The psychophysiological response of 22 professional soldiers in a CQC before and after an experimental 2-week operative HIIT was analyzed. Training intervention produced a significant increase in blood lactate, isometric hand-grip strength, perceived stress, rates of perceived exertion, anxiety response, heart rate, and autonomic sympathetic modulation and a significant decrease in cortical arousal requirements. An experimental operative high-intensity interval training produced an increase on the psychophysiological operativity for CQC scenarios, increasing the sympathetic and physiological response and decreasing the cortical arousal requirement of soldiers.Koefoed, N, Dam, S, and Kersting, UG. Effect of box height on box jump performance in elite female team handball players. J Strength Cond Res XX(X) 000-000, 2020-This study aimed at investigating whether a link exists between performance in a countermovement jump and the height of the box an athlete could successfully jump onto. Furthermore, it was investigated whether the height of the box influences the takeoff. Ten, elite, female team, handball players were recruited for the study (age 20.9 ± 3.2 years; height 174.7 ± 7.6 cm; mass 73.8 ± 6.7 kg). Subjects performed 3 maximal countermovement jumps. Subsequently, subjects jumped onto boxes of increasing height until they could no longer successfully jump onto the box. Subjects then performed 3 box jumps with maximal intention to boxes corresponding to 70% of their maximal center of mass displacement (LOW) and 90% of their maximal achieved box height (HIGH). Finally, subjects completed another 3 maximal countermovement jumps. There was no relationship between the maximal center of mass displacement in countermovement jumps and the maximal achievable box jump height (r = 0.35; p = 0.071). Between jumps to LOW and HIGH boxes, there were no differences in the chosen variables, peak force (-156 ± 390 N; p = 0.239), peak power (25 ± 236 W; p = 0.747), peak center of mass displacement (0.003 ± 0.039 m; p = 0.840), peak rate of force development (-3.055 ± 6264 N·s; p = 0.157), and concentric time to takeoff (0.005 ± 0.044 seconds; p = 0.721). PYR41 Because no differences could be found, the added risk of failure leading to injury and the limited possibilities of improving specific landing technique with low impact when jumping to high boxes in training cannot be justified.Comfort, P, Jones, PA, Thomas, C, Dos'Santos, T, McMahon, JJ, and Suchomel, TJ. Changes in early and maximal isometric force production in response to moderate- and high-load strength and power training. J Strength Cond Res XX(X) 000-000, 2020-The aims of this study were to determine the changes in early (50-, 100-, 150-, 200-, 250 ms) and maximal isometric force production, in response to a 4-week period of moderate-load resistance training (60-82.5% 1 repetition maximum [1RM]), followed by a 4-week period of high-load (80-90% 1RM) resistance training. Thirty-four subjects (age 19.5 ± 2.8 years; height 1.72 ± 0.08 m; body mass 69.9 ± 11.4 kg; maximal power clean 0.92 ± 0.03 kg·kg) participated in this study. Only trivial-to-moderate (0.2-2.7%, d = 0.00-0.88) and nonsignificant (p > 0.05) changes in early isometric force production were observed in response to the moderate-load training period, whereas very large (9.2-14.6%, d = 2.71-4.16), significant (p ≤ 0.001) increases in early isometric force production were observed in response to high-load training. In contrast, there was a very large, significant increase in peak force (PF) across the moderate-load phase (7.7 ± 11.8%, d = 2.02, p = 0.003), but only a moderate significant increase in PF (3.8 ± 10.6%, d = 1.16, p = 0.001) across the high-load phase. The results of this study indicate that high-load multijoint resistance training, that follows moderate-load training, results in superior increases in early multi-joint force production, compared with the changes observed after moderate-load resistance training.