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PURPOSE: Agility in young soccer players has long been associated with physical attributes like strength, speed, and power. The aims of this study were to investigate the relationship between cognitive factors and agility performance in this unique population. METHODS: 39 young soccer players age 13.56 (SD 0.58) years were assessed for leg-muscle function (jump tests) and maturation status (peak height velocity). The Y-Agility Test, which included decision making in players, was used to measure performance. Cognitive factors such as perceptual skills and decision making were evaluated with the Y-Agility Test. RESULTS: The linear regression showed an absence of significance between the Y-Agility Test and drop-jump contact (P = .283), Y-Agility Test and drop-jump flight (P = .185), Y-Agility Test and squat jump (P = .868), and Y-Agility Test and countermovement jump (P = .310). The linear mixed-model analyses suggested a difference between early-average maturers (P = .009) and early-late maturers (P = .005) but did not show a difference between average-late subjects (P = 1.000). Drop-jump flight did not show a difference in maturation (early-average P = 1.000; early-late P = 1.000; average P = 1.000). Squat-jump performance did not demonstrate any significance (early-average P = .618; early-late P = 1.000; P = 1.000). Countermovement-jump performance did not show any significance (early-average P = 1.000; early-late P = 1.000; average-late P = .492). Finally, agility performance does not show any significance between maturation levels (early-average maturer P = .450; early-late P = 1.000; average-late P = .830). CONCLUSION: Agility in young soccer players appears to follow a nonlinear trajectory, with cognitive factors possibly playing a more significant role than previously thought.

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The aim of this study was to investigate how physical fitness performance, which is related to the strength and power of the lower extremities and core, as well as lateral agility, changes across 20 weeks of in-season training in youth female and male padel players. This study was conducted using a prospective cohort design on 16 Swedish high school padel players aged between 15 and 18 years old. The players were assessed at baseline with five tests of their physical fitness and followed prospectively, with the registration of their training load for 20 weeks, and then assessed at a follow-up, approximately five months later. The players increased their performance in all tests (p ≤ 0.02). The mean improvement in their Isometric squat test performance was 20% for peak force, 18% for relative strength value and 69% for average rate of force development. Their improvement in the squat jump test performance was 9%, whereas the improvement in their countermovement jump test was 6%. For the 30 second sit-up test, an improvement of 14% was observed. Improvements were also noted for the 30 second side hop test performance on both the right (9%) and left leg (11%). The effect size ranged from 0.31 to 1, respectively, for the tests, representing a small to large effect. The data from this study suggest that an improvement in physical fitness performance can be obtained during 20 weeks of padel training.

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Caffeine (CAF) has been shown to be an effective ergogenic aid in enhancing sports performance, including vertical jump (VJ), sprint, balance, agility, and freestyle swimming performance (FSP). However, whether acute CAF supplementation improves FSP in moderately trained female swimmers has not been well documented. Therefore, this study aimed to investigate the effects of CAF intake on vertical jump, balance, auditory reaction time (ART), and swimming performance in female swimmers. In a double-blind, cross-over design, eight moderately trained female swimmers (age: 21.3 ± 1.4 years, height: 161.2 ± 7.1 cm, body mass: 56.3 ± 6.7 kg, body mass index (BMI): 21.9 ± 1.3 kg/m2, and habitual CAF intake: 246.4 ± 111.4 mg/day) ingested caffeine (CAF) (6 mg/kg) or a placebo (PLA) 60 min before completing VJ, balance, ART, and 25/50 m FSP. CAF supplementation resulted in a significantly lower time both in 25m (p = 0.032) and 50m (p = 0.033) FSP. However, CAF resulted in no significant difference in VJ, ART, and RPE (p > 0.05). Balance test results showed a non-significant moderate main effect (d = 0.58). In conclusion, CAF seems to reduce time in short-distance swimming performances, which could be the determinant of success considering the total time of the race. Thus, we recommend coaches and practitioners incorporate CAF into swimmers' nutrition plans before competitions, which may meet the high performance demands.

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Background: Swim performance can be reliant on strength and power. Standardisation of swim performance in different events, distances, and sexes can be completed using World Aquatics points, allowing for ranking of swimmers. The aim of this retrospective cross-sectional study was to assess whether relationships between World Aquatics points and dryland markers of performance existed in male and female elite swimmers separately and combined. Methods: Dryland tests included Optojump® photoelectric cell countermovement jump, countermovement jump reach with a Vertec® system, standing broad jump using a tape measure, repetition maximum testing in the barbell back squat, barbell deadlift, and barbell bench press. Swim performance data and dryland test data on elite male (n = 38) and female (n = 20) Scottish swimmers from 2009-2017 were collected. Swim performance data were converted to World Aquatics federation points, and Bayesian linear regression analyses examined relationships between World Aquatics points and dryland performance tests: countermovement jump height (cm) using an Optojump® photoelectric cells system, countermovement jump height (cm) using a Vertec® device, standing broad jump distance (cm), relative strength (load lifted (kg) per kg of body mass) in the barbell bench press (kg/kg), barbell back squat (kg/kg), barbell deadlift (kg/kg). Results: The Bayesian estimates of change of World Aquatics points for a unit change in jump-based measures were: Optojump®-men = 0.6, women = 0.6, combined = 0.4; Vertec®-men = 4.3, women = -1.6, combined = 2.4; standing broad jump-men = 0, women = 0, combined = 0.4. Strength-based measures were: barbell back squat-men = 2.3, women = 22, combined = -2.5; barbell deadlift-men = -5; barbell bench press-men = 41.8. Conclusions: Dryland performance tests are not good predictors of World Aquatics points and should rather be used for assessing training quality and monitoring injury risks.

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The aim of the present study was to analyze the sporting progression from U14 to senior categories of elite Spanish high and long jumpers. For prospective analysis, 300 athletes ranked top 20 at U14 were analyzed (153 female and 147 male). For retrospective analysis, 64 athletes ranked in the top 20 in the senior category were included (21 female and 43 male). Ranking positions were registered in each of the seasons where they presented records. Only 6.3% (19) of athletes who reached the top 20 at U14 became successful senior athletes [4.7% (14) of athletes maintained top 20 status throughout their sporting careers from U14 to senior]. The transition rate from U14 to U16 (35.7%) was the most severe drop down in consecutive categories (after this, it ranged from 47.8 to 66.7%). Of the senior top 20 athletes (64), most of them were already ranked top 20 at U16 (59.4%, 38), at U18 (62.5%, 40), at U20 (70.3%, 45) and at U23 (78.1%, 50). Nevertheless, only 34.4% (22) were top 20 when they were U14 athletes. Transition rates in the top 20 senior athletes ranged from 86.7 to 95.5%. Around one out of four (26.6%, 17) of the top 20 senior athletes maintained top 20 status throughout their sporting careers from U14 to the senior category. Although early success is not a good predictor of senior success, successful senior athletes excelled early on and were able to remain in top rankings throughout their sporting careers of national elite jumpers.

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The aim of this study was to compare the effects of two velocity-based resistance training (RT) programs using moderate loads (45-60% 1RM) but different magnitudes of velocity loss (VL) limits (10% vs. 30%) on the changes in physical performance in young soccer players. Twenty young soccer players were randomly allocated into two groups: VL10% (n = 10) and VL30% (n = 10). All participants were assessed before and after the 8-week RT program (twice a week) involving the following tests: 20 m running sprint (T20), countermovement jump (CMJ), kicking a ball (KB), and progressive loading test in the full squat (SQ) exercise. The RT program was conducted using only the SQ exercise and movement velocity was monitored in all repetitions. Significant 'time × group' interaction (p < 0.05) was observed for sprint performance, KB and 1RM in the SQ exercise in favor of VL10%. No significant changes between groups at post-test were observed. The VL10% resulted in significant (p < 0.05-0.001) intra-group changes in all variables analyzed, except for KB, whereas VL30% only showed significant (p < 0.05) performance increments in a sprint test and 1RM in the SQ exercise. The percentage of change and the intra-group's effect size were of greater magnitude for VL10% in all variables analyzed compared to VL30%. In conclusion, our results suggest that, for non-trained young soccer players, squat training with low to moderate relative loads and 10%VL is sufficient to elicit significant increases in muscle strength and sport-specific actions compared to 30%VL in the set.

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BACKGROUND: Although recent studies have investigated the effects of flywheel (FW) training on muscle function, the effects of transient FW exercise on jump performance in athletes are unknown. This study examined the effects of single and repeated bouts of FW squat exercises on jump performance and muscle damage in male collegiate basketball players. METHODS: The participants were 10 healthy college-age men (nonathletes) and 11 male basketball players (athletes). The intervention involved 100 squat exercises (10 repetitions × 10 sets) using an FW device. To examine the repeated-bout effects, the protocol was conducted again after a 2-week interval. Squat jumps, countermovement jumps, drop jumps, and rebound jumps were evaluated as jump performance, while isometric maximal voluntary contraction (MVC) torque in knee extension, muscle soreness, range of motion, thigh circumference, muscle thickness, and echo intensity were evaluated as markers of muscle damage. Measurements were taken at baseline, immediately after exercise, 24 h later, and 72 h later. RESULTS: The jump performance of nonathletes decreased after exercise (p < 0.05), while that of the athletes did not. The results were similar for muscle soreness. MVC torque decreased significantly after the first exercise in both groups (p < 0.05) and was significantly lower in the nonathletes versus athletes. Significant repeated-bout effects were found for muscle soreness in nonathletes but not athletes. CONCLUSIONS: These results suggest that a single bout of FW exercise reduces jump performance in male nonathletes but not basketball players.

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The effects of contrast water therapy (CWT) on dehydration at moderate altitudes during training camps remain unknown. We hypothesized that CWT reduces dehydration resulting from training at moderate altitudes and improves performance, akin to conditions at sea level. A 13-day endurance training camp was held at a moderate altitude of 1100 m and included 22 university athletes, who were divided into two groups (CWT group, n = 12; control (CON) group, n = 10). The sample size was calculated based on an α level of 0.05, power (1 ß) of 0.8, and effect size of 0.25 based on two-way ANOVA. Longitudinal changes over 13 days were compared using a two-group comparison model. Additionally, 16 athletes participated in an additional performance verification analysis. Subjective fatigue, body mass, and water content (total body water (TBW), extracellular water (ECW), and intracellular water) were measured using bioimpedance analysis every morning, and the titin N-terminal fragment in urine (UTF) was measured as an index of muscle damage. For performance verification, 10 consecutive jump performances (with the reactive strength index (RSI) as an indicator) were evaluated as neuromuscular function indices. The results indicated that the UTF did not significantly differ between the two groups. Moreover, the ECW/TBW values, indicative of dehydration, on days 4 and 5 in the CWT group were significantly lower than those in the CON group. However, there was no significant difference in RSI between the two groups. Therefore, although CWT reduces dehydration in the early stages of the training camp, it may not affect performance.

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Low-load blood flow restriction training (BFRT) has been shown to induce a significant increase in muscle activation. However, low-load BFRT to augment the post-activation performance enhancement (PAPE) has not been previously examined. This study aimed to examine the PAPE of low-intensity semi-squat exercises with varying pressure BFRT on vertical height jump performance. Twelve elite athletes from the Shaanxi Province women's football team volunteered to participate in this study for 4 weeks. Participants completed four testing sessions that included one of the following at random: (1) non-BFRT, (2) 50% arterial occlusion pressure (AOP), (3) 60% AOP, or (4) 70% AOP. Muscle activity of the lower thigh muscles was recorded using electromyography (EMG). Jump height, peak power output (PPO), vertical ground reaction forces (vGRF), and rate of force development (RFD) were recorded for four trials. Two-factor repeated measures analysis of variance (ANOVA) showed that semi-squat with varying pressure BFRT had a significant impact on the measured muscle EMG amplitude and MF value of vastus medialis, vastus lateralis, rectus femoris, and biceps femoris (P < 0.05), and MF value decreased with increasing pressure. Muscle activation (EMG amplitude) did not change further. The EMG amplitude of the gluteus maximus was significantly decreased by semi-squat training with different pressures (P < 0.05), while that of the gluteus maximus muscle was gradually increased by non-BFR with semi-squat training (P > 0.05). The 50% and 60% AOP BFRTs significantly increased jump height, peak power, and force increase rate (RFD) after 5 min and 10 min of rest (P < 0.05). This study further confirmed that low-intensity BFRT can significantly increase lower limb muscle activation, induce PAPE, and improve vertical height jump in female footballers. In addition, 50% AOP continuous BFRT is recommended for warm-up activities.

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The primary purpose of this study was to examine sex differences in lower extremity joint stiffness during vertical drop jump performance. A secondary purpose was to examine the potential influence of sex on the relationship between joint stiffness and jump performance. Thirty healthy and active individuals performed 15-drop jumps from 30 and 60 cm boxes. Hip, knee, and ankle joint stiffnesses were calculated for subphases of landing using a 2nd order polynomial regression model. Males had greater hip stiffness during the loading phase in drop jumps from both box heights than females' drop jump from 60 cm box. Also, males had a greater ground reaction force at the end of eccentric phase, net jump impulse, and jump height regardless of box height. The 60 cm box height increased knee stiffness during the loading phase, but reduced hip stiffness during the loading phase and knee and ankle stiffness during the absorption phase regardless of sex. Joint stiffnesses significantly predicted drop jump height for females (p < .001, r2 = 0.579), but not for males (p = .609, r2 = -0.053). These results suggest that females may have different strategies to maximize drop jump height as compared to males.

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Prolonged periods of increased physical demands can elicit anabolic tendon adaptations that increase stiffness and mechanical resilience or conversely can lead to pathological processes that deteriorate tendon structural quality with ensuing pain and potential rupture. Although the mechanisms by which tendon mechanical loads regulate tissue adaptation are largely unknown, the ion channel PIEZO1 has been implicated in tendon mechanotransduction, with human carriers of the PIEZO1 gain-of-function variant E756del displaying improved dynamic vertical jump performance compared with noncarriers. Here, we sought to examine whether increased tendon stiffness in humans could explain this increased performance. We assessed tendon morphological and mechanical properties with ultrasound-based techniques in 77 participants of Middle- and West-African descent, and we measured their vertical jumping performance to assess potential functional consequences in the context of high tendon strain-rate loading. Carrying the E756del gene variant (n = 30) was associated with 46.3 ± 68.3% (P = 0.002) and 45.6 ± 69.2% (P < 0.001) higher patellar tendon stiffness and Young's modulus compared with noncarrying controls, respectively. Although these tissue level measures strongly corroborate the initial postulate that PIEZO1 plays an integral part in regulating tendon material properties and stiffness in humans, we found no detectable correlation between tendon stiffness and jumping performance in the tested population that comprised individuals of highly diverse physical fitness level, dexterity, and jumping ability.NEW & NOTEWORTHY The E756del gene variant causes overactivity of the mechanosensitive membrane channel PIEZO1 and is suspected to upregulate tendon collagen cross linking. In human carriers of E756del, we found increased patellar tendon stiffness but similar tendon lengths and cross-sectional areas, directly supporting the premise that PIEZO1 regulates human tendon stiffness at the level of tissue material properties.

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Flywheel resistance training devices (FRTD) is shown effective in improving strength, sprinting, jumping and changes of direction (COD) performance in male soccer players, however, this is not elucidated in female soccer players. We aimed to assess the effect of FRTD on these physical abilities in females soccer players. 24 professional female soccer players (age: 20.4 ± 2.6 years) were randomly assigned to a flywheel training group (FWTG) that trained twice a week for 6 weeks on a rotary inertia device with an initial volume of 3 sets of 6 repetitions and an inertia of 0,025 kg · m-2, increasing intensity and volume or a control group (CG) that did not performed any additional resistance training program. Concentric peak torque of the knee extensors (CONEXT) and flexors (CONFLEX), eccentric peak torque of the knee extensors (ECCEXT) and flexors (ECCFLEX) at 60° · s-1 on an isokinetic dynamometer, countermovement jump (CMJ) height, COD and 30-metres sprint were assessed. Significant time by group interactions were found in CONEXT (p = 0.002; η²p = 0.425), CONFLEX (p = 0.037; η²p = 0.22), ECCEXT (p = 0.002; η²p = 0.43) and ECCFLEX (p = 0.008; η²p = 0.334). No time by group effect was found in CMJ (p = 0.061; η²p = 0.182), COD (p = 0.067; η²p = 0.184) or sprint (p = 0.926; η²p = 4.979 · e-4). In conclusion, 6 weeks of flywheel squat training improved strength (especially eccentric strength) but not soccer-specific abilities such as jumping, changing of direction or sprinting in professional soccer players.

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Handball is one of the most popular team sports around the world that has become physically very demanding, related to both competitions and daily training sessions. Optimal training programs are necessary to improve performance, especially when taking into account the frequency of jump shots (vertical jumps) and handball feints (changes of directions) during daily training. The main objective of the present study is to review the available literature systematically, and to determine what are the effects of additional plyometric training on handball players' vertical jump abilities. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis, six studies were selected after a systematic search through four digital databases: Web of Science, PubMed, Scopus, and ScienceDirect. The available scientific articles show that plyometric training alone or in combination with standard handball training, lasting at least six weeks, and including two training sessions per week, contributes to improving the performance of elite- or national-level handball players. Plyometric training is recommended to improve performance, as well as to maintain explosive strength parameters during the season.

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Cluster sets (CS) are effective in maintaining performance and reducing perceived effort compared to traditional sets (TRD). However, little is known about these effects on adolescent athletes. The purpose of this study was to compare the effect of CS on the performance of mechanical and perceptual variables in young athletes. Eleven subjects [4 boys (age = 15.5 ± 0.8 years; body mass = 54.3 ± 7.0 kg; body height = 1.67 ± 0.04 m; Back Squat 1RM/body mass: 1.62 ± 0.19 kg; years from peak height velocity [PHV]: 0.94 ± 0.50) and 7 girls (age = 17.2 ± 1.4 years; body mass = 54.7 ± 6.3 kg; body height = 1.63 ± 0.08 m; Back Squat 1RM/body mass: 1.22 ± 0.16 kg; years from PHV: 3.33 ± 1.00)] participated in a randomized crossover design with one traditional (TRD: 3 × 8, no intra-set and 225 s interest rest) and two clusters (CS1: 3 × 2 × 4, one 30 s intra-set and 180 s inter-set rest; and CS2: 3 × 4 × 2, three 30 s intra-set and 90 s inter-set rest) protocols. The subjects were assessed for a Back Squat 1RM for the first meet, then performed the three protocols on three different days, with at least 48 h between them. During experimental sessions, a back squat exercise was performed, and mean propulsive velocity (MPV), power (MPP), and force (MPF) were collected to analyze performance between protocols, together with measures of countermovement jump (CMJ) and perceptual responses through Rating of Perceived Exertion for each set (RPE-Set) and the overall session (S-RPE), and Muscle Soreness (DOMS). The results showed that velocity and power decline (MVD and MPD) were favorable for CS2 (MVD: -5.61 ± 14.84%; MPD: -5.63 ± 14.91%) against TRD (MVD: -21.10 ± 11.88%; MPD: -20.98 ± 11.85%) (p < 0.01) and CS1 (MVD: -21.44 ± 12.13%; MPD: -21.50 ± 12.20%) (p < 0.05). For RPE-Set, the scores were smaller for CS2 (RPE8: 3.23 ± 0.61; RPE16: 4.32 ± 1.42; RPE24: 4.46 ± 1.51) compared to TRD (RPE8: 4.73 ± 1.33; RPE16: 5.46 ± 1.62; RPE24: 6.23 ± 1.97) (p = 0.008), as well as for Session RPE (CS2: 4.32 ± 1.59; TRD: 5.68 ± 1.75) (p = 0.015). There were no changes for jump height (CMJ: p = 0.985), and the difference between time points in CMJ (ΔCMJ: p = 0.213) and muscle soreness (DOMS: p = 0.437) were identified. Our findings suggest that using CS with a greater number of intra-set rests is more efficient even with the total rest interval equalized, presenting lower decreases in mechanical performance and lower perceptual effort responses.

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PURPOSE: Most high-intensity bouts of exercise in volleyball consist of jumping activities, which are responsible for inducing muscle damage, high levels of fatigue, and muscle soreness. Therefore, the aim of the current study was to quantify and analyze the training loads, neuromuscular fatigue, and perceptual well-being of a 5-week in-season mesocycle carried out by a professional male volleyball team. METHODS: Fifteen volleyball players (age 28.51 [5.39] y; height 193.19 [9.87] cm; body mass 88.46 [13.18] kg) participated in this study. Internal training load assessed through the rating of perceived exertion, external training load (ETL; evaluated using an inertial motion unit), countermovement jump (CMJ) height and peak power, and wellness questionnaire responses were obtained from all athletes. RESULTS: Results indicated a progressive decrease of the internal training load during the week and by the undulatory pattern of the ETL during the microcycles. Moreover, training monotony increased across the microcycles and was negatively associated with CMJ peak power (r = -.681, P < .05). Finally, sleep quality (ρ = -.747, P < .01) and fatigue (ρ = -.789, P < .01) were negatively associated with weekly ETL. CONCLUSIONS: This study indicated that sleep quality and fatigue were negatively associated with weekly ETL. Therefore, decreases in weekly ETL might be needed to improve sleep quality and decrease fatigue in professional volleyball players. Plus, higher values of training monotony were associated with lower values of CMJ peak power. Consequently, avoiding training monotony might be important to improve jumping performance in professional volleyball athletes.

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The purpose of this study was to investigate the effects of foot positioning and lean mass on jumping and landing mechanics in collegiate dancers. Thirteen dancers performed 3 unilateral and bilateral vertical jumps with feet in neutral and turnout positions. Dual-energy x-ray absorptiometry scans, jump height, vertical stiffness, and joint stiffness were assessed for relationships between foot positions. Jump heights were greater in right compared with left limb (P = .029) and neutral compared with turnout (P = .020) during unilateral jumping. In unilateral landing, knee stiffness was greater in turnout compared with neutral (P = .004) during the loading phase. Jump height (P < .001) was significantly increased, and vertical stiffness (P = .003) was significantly decreased during bilateral jumping in neutral compared with turnout. Significantly increased hip stiffness during the attenuation phase was observed in neutral compared with turnout (P = .006). Left-limb lean mass was significantly less than the right limb (P < .05). Adjustments for bilateral jumping were focused on hip stiffness, whereas there was a slight shift to knee strategy for unilateral jump.

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To identify and evaluate current scientific literature concerning the effect of strength, power and speed training on relevant physiological and biomechanical characteristics and performance of competitive cross-country skiers (XCS), the databases Scopus and PubMed were searched systematically for original articles in peer-reviewed journals. Of the 599 studies retrieved, 12 met the inclusion criteria (i.e., assessment of outcome measures with relevance for XCS performance; involvement of traditional resistance training; application of external resistance to the body; intervention longer than 4 weeks; randomized controlled trial). The methodological rigor of each study was assessed using the PEDro scale, which were mostly poor-to-fair, with good methodological quality in only two articles. All of the strength/power/speed interventions improved 1RM (0.8-6.8 ES), but findings with respect to jump performance, ability to generate force rapidly and body composition were mixed. Interventions demonstrated moderate-to-high ES on XCS specific performance compared with control (mean ES = 0.56), but the pattern observed was not consistent. None of the interventions changed anaerobic capacity, while in most studies VO2max was either unchanged or increased. Work economy or efficiency was enhanced by most of the interventions. In conclusion, present research indicates that strength training improves general strength, with moderate effects on XCS performance, and inconclusive effects on work economy and VO2max/VO2peak. Strength training with high loads, explosive strength training, or sprint interval training seem to be promising tools for modern XCS training. Future investigations should include long-term (e.g., >6 months) strength training to allow sufficient time for increased strength and speed to influence actual XCS performance. Moreover, they should include both sexes, as well as upper- and lower-body muscles (trained separately and together) and employ free weights and core training. Methodological differences and limitations highlighted here may explain discrepancies in findings and should be taken into consideration in future research in this area.

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There are many reasons for reduced physical activity leading to reduced maximal strength and sport-specific performance, such as jumping performance. These include pandemic lockdowns, serious injury, or prolonged sitting in daily work life. Consequently, such circumstances can contribute to increased morbidity and reduced physical performance. Therefore, a demand for space-saving and home-based training routines to counteract decreases in physical performance is suggested in the literature. This study aimed to investigate the possibility of using daily static stretching using a stretching board to counteract inactivity-related decreases in performance. Thirty-five (35) participants were either allocated to an intervention group (IG), performing a daily ten-minute stretch training combined with reduced physical activity or a reduced physical activity-only group (rPA). The effects on maximal voluntary contraction, range of motion using the knee-to-wall test, countermovement jump height (CMJheight), squat jump height (SJheight), drop jump height (DJheight), contact time (DJct) and the reactive strength index (DJRSI) were evaluated using a pre-test-post-test design. The rPA group reported reduced physical activity because of lockdown. Results showed significant decreases in flexibility and jump performance (d = -0.11--0.36, p = 0.004-0.046) within the six weeks intervention period with the rPA group. In contrast, the IG showed significant increases in MVC90 (d = 0.3, p < 0.001) and ROM (d = 0.44, p < 0.001) with significant improvements in SJheight (d = 0.14, p = 0.002), while no change was measured for CMJheight and DJ performance. Hence, 10 min of daily stretching seems to be sufficient to counteract inactivity-related performance decreases in young and healthy participants.

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Due to the time is, commonly, a barrier to exercise, the scientific community has paid attention to a new model of training. Repeated-sprint hypoxic training is now considered an effective time-efficient method for improving physical performance in different sport modalities. However, few researchers have studied the effect of this strategy in healthy untrained or moderately trained individuals. Depending of the prior fitness status, different findings may be obtained. Therefore, this study determined the effects of 4 weeks of repeated-sprint in hypoxia on cardiorespiratory fitness and anaerobic capacity in healthy men. Twenty-four physically active males (were randomly assigned to repeated-sprint in normoxia (n=8; 0.20 FiO2 ), in hypoxia (n=8; 0.14 FiO2 ) or a control group (n=8). Participants of both exercise groups developed eight training sessions consisted of 2 sets of 5 all-out cycling sprints of 10 s with a recovery of 20 s between sprints and 10 min between sets. Repeated sprint ability, vertical jump performance and estimated maximal oxygen consumption were tested at baseline, 7 days and 2 weeks after the last session. Seven days after the last sessions, significant differences (p<0.05) between normoxia (+7.8%; p<0.001; ES=1.66) and hypoxia groups (+9.9%; p=0.000; ES=1.42) compared with control group were found in estimated maximal oxygen consumption. In the hypoxia group, the number of sprints to exhaustion (7 days Post +55.6%; ES=1.40; 2 weeks Post +10.0%; ES=1.80) improved with a large effect size at 7 days and 2 weeks after the last sessions compared with baseline. Eight sessions of repeated-sprint training in hypoxia conditions could produce improvements and delayed effects on anaerobic capacity.(AU)

La comunidad científica ha prestado atención en los últimos años a un nuevo modelo de entrenamiento, debido a que la falta de tiempo es comúnmente la principal barrera para la práctica deportiva. En este contexto, el entrenamiento de esprint repetidos en hipoxia es considerado como una prometedora estrategia para mejorar el rendimiento físico en diferentes modalidades deportivas. Sin embargo, existen pocos estudios que investiguen los efectos sobre población moderadamente entrenada o sedentaria. Así, este estudio determina los efectos de un entrenamiento de esprint repetidos en hipoxia sobre la condición física de hombres sanos. Veinticuatro hombres fueron asignados aleatoriamente a un grupo normoxia (n=8; 0.20 FiO2 ), hipoxia (n=8; 0.14 FiO2 ) o control (n=8). Después de ocho sesiones de esprint repetido en cicloergómetros de 10s, la habilidad de esprint repetido, el rendimiento en el salto vertical, así como el consumo de oxígeno fueron evaluados en la línea base y a los días y 2 semanas de la última sesión de entrenamiento. A los 7 días, se observaron diferencias significativas entre normoxia (+7,8%; p<0.001; ES=1,66) e hipoxia (+9,9%; p=0,000; ES=1,42) comparado con el grupo control en el consumo máximo de oxígeno estimado. En hipoxia, el número de esprint hasta la extenuación (7 días Post +55,6%; ES=1,40; 2 semanas Post +10,0%; ES=1,80) también mejoró con tamaño del efecto elevado a los 7 días y 2 semanas de la última sesión comparado con la línea base. El protocolo de 8 sesiones de esprines repetido en hipoxia podría producir mejoras y retrasar los efectos sobre el rendimiento anaeróbico de hombres sanos. (AU)

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Objectives: In Italy, in 2013, a new school curriculum with a sport character was established in high schools, called Sports High School (SHS). The aims of this study were: (1) to assess the fitness levels of SHS students who, respecting all the safety rules to limit the spread of COVID-19, practiced physical education (PE) at school with continuity for almost all of 2021, and to compare them with Traditional High School (THS) students; (2) to evaluate as the SHS may have influenced the fitness levels in adolescents. Methods: This is a case-control study in which thirty participants were enrolled (SHS: n = 15; THS: n = 15). To assess the fitness levels, the following tests were administered: the Static Baropodometric and Stabilometric Analyses, the Counter Movement Jump (CMJ), and the Handgrip test. All these tests were administered when the non-pharmaceutical interventions (NPIs) for COVID-19 allowed the resumption of PE lessons (T0) and 2 months after their resumption (T1). Results: Unpaired t-test between SHS (T0) vs. THS (T0) showed significant differences between: Handgrip test Dx and Handgrip test Sx (both p < 0.001), Surface Sx foot and Surface Dx foot (both p < 0.05), and CMJ (p < 0.001). These results were also confirmed in T1. The performance analysis between T0 and T1 of both SHS and THS showed improvements in SHS: Handgrip test Dx (p < 0.05; d = 0.57), Handgrip test Sx (p < 0.01; d = 0.87), and CMJ (p < 0.05; d = 0.59). Pearson's analysis of the results of the tests showed significant strong correlations between: Handgrip test Dx and Handgrip test Sx (R = 0.959; p < 0.001), Handgrip test Dx and CMJ (R = 0.881; p < 0.001), Handgrip test Sx and CMJ (R = 0.893; p < 0.001). The same analysis showed significant but moderate correlations between: Surface foot Sx and CMJ (R = 0.489; p < 0.01), Surface foot Sx and y-mean (R = 0.485; p < 0.01), Surface foot Dx and CMJ (R = 0.444; p < 0.05). Conclusions: This study is in agreement with the literature showing that the quarantine period and the NPIs for COVID-19 caused a decrease in fitness levels in adolescents. Our results showed that students of SHS recorded higher strength performance both in the Handgrip test and in the CMJ.

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