Influence of short vs. long repetition sprint training on selected fitness components in young soccer players

The aim of this study was to compare the effect of short-sprint repetition and long-sprint repetition training (SST, LST), matched for total distance, on selected fitness components in young soccer players. Thirty young (14-15 years) soccer players were randomly assigned to either the short-sprint training group or long-sprint training group and completed 2 similar sets of fitness tests before and after 7 weeks of training. The 2 training programs consisted of SST (4-6 sets of 4 × 50-m all-out sprint) and LST (4-6 sets of 200-m run at 85% of maximum speed), each performed 3 times a week. Before training, there were no baseline between-group differences in predicted VO2max, standing long jump, 30-m sprint time, 4 × 10-m shuttle running time, and 250-m running time. Both training programs led to a significant improvement in VO2max (predicted from the 20-m shuttle run, p < 0.01), with no between-group difference (p = 0.14). Both training programs also led to a significant improvement in the anaerobic fitness variables of 30-m sprint time (p < 0.01), 4 × 10-m shuttle running time (p < 0.01), and 250-m running time (p < 0.01), with no between-group differences. Neither of the training programs had a significant effect on standing long jump (p = 0.21). The study showed that long, near-maximal sprints, and short, all-out sprint training, matched for total distance, are equally effective in enhancing both the aerobic and anaerobic fitness of young soccer players. Therefore, to maintain a player's training interest and enthusiasm, coaches may alternate between these methods during the busy soccer season.     

Effects of 5 weeks of high-intensity interval training vs. volume training in 14-year-old soccer players

High-intensity interval training (HIIT) in junior and adult soccer has been shown to improve oxygen uptake (VO?) and enhance soccer performance. The main purpose of this study was to examine the short term effects of a 5-week HIIT vs. high-volume training (HVT) program in 14-year-old soccer players regarding the effects on VO?max and 1,000-m time (T????) and on sprinting and jumping performance. In a 5-week period, 19 male soccer players with a mean (SD) age of 13.5 ± 0.4 years performed HIIT at close to ~90% of maximal heart rate. The HVT intensity was set at 60-75% of maximal heart rate. VO?max increased significantly (7.0%) from pre to post in HIIT but not after HVT. T???? decreased significantly after HIIT (~-10 vs. ~-5 seconds in HVT). Sprint performance increased significantly in both groups from pre to posttesting without any changes in jumping performance.     

Resisted sprint training with partner towing improves explosive force and sprint performance in young soccer players – a pilot study

The purpose of this study was to examine the effects of non-resisted (NRS) and partner-towing resisted (RS) sprint training on legs explosive force, sprint performance and sprint kinematic parameters. Sixteen young elite soccer players (age 16.6 ± 0.2 years, height 175.6 ± 5.7 cm, and body mass 67.6 ± 8.2 kg) were randomly allocated to two training groups: resisted sprint RS (n = 7) and non-resisted sprint NRS (n = 9). The RS group followed a six-week sprint training programme consisting of two “sprint training sessions” per week in addition to their usual soccer training. The NRS group followed a similar sprint training programme, replicating the distances of sprints but without any added resistance. All players were assessed before and after training: vertical and horizontal jumping (countermovement jump (CMJ), squat jump (SJ), and 5-jump test (5JT)), 30 m sprint performance (5, 10, and 20 m split times), and running kinematics (stride length and frequency). In the RS group significant (p < 0.05) changes were: decreased sprint time for 0–5 m, 0–10 m and 0–30 m (-6.31, -5.73 and -2.00%; effect size (ES) = 0.70, 1.00 and 0.41, respectively); higher peak jumping height (4.23% and 3.59%; ES = 0.35 and 0.37, for SJ and CMJ respectively); and 5JT (3.10%; ES = 0.44); and increased stride frequency (3.96%; ES = 0.76). In the NRS group, significant (p < 0.05) changes were: decreased sprint time at 0–30 m (-1.34%, ES = 0.33) and increased stride length (1.21%; ES = 0.17). RS training (partner towing) for six weeks in young soccer players showed more effective performances in sprint, stride frequency and lower-limb explosive force, while NRS training improved sprint performance at 0–30 m and stride length. Consequently, coaches and physical trainers should consider including RS training as part of their sprint training to ensure optimal sprint performance.     

Effects of heavy barbell hip thrust vs back squat on subsequent sprint performance in rugby players

The objective of this research was to compare the effect of Post-Activation Performance Enhancement (PAPE) exerted on the back squat (BS) versus the barbell hip thrust (HT) on the sprint performance (5- and 10-m). 17 male amateur rugby players participated in the study (age 22.14 ± 2.52 years; body mass 81.06 ± 9.6 kg; height 1.78 ± 0.05 m). All participants performed a dynamic maximum strength test (3RM) in BS and HT at maximum speed. Two randomized sessions were performed inducing PAPE using BS or HT trough three series with three repetitions at 85% 1RM eight minutes before the sprint tests. An ANOVA of repeated measurement, found no differences in the time for 5-m (F = 0.398, P = 0.537, η²p = 0.024) or 10-m (F = 2.589, P = 0.127, η²p = 0.139). There were no significant differences in the Protocol effect between HT and BS in 5-m or 10-m (F = 2.963, P = 0.104, η²p = 0.156 and F = 1.472, P = 0.243 η²p = 0.084, respectively). There were also no differences in the Time x Protocol interaction at 5-m (F = 0.001, P = 0.976, η²p < 0.001) or 10-m (F = 4.174, P = 0.058, η²p = 0.207). The effect size obtained in the results of the sprint tests was small in both exercises (ES < 0.2). None of the BS or HT exercises performed with heavy load induced a significant PAPE phenomenon on the ability to sprint in rugby players.     

The effects of training on hormonal concentrations in young soccer players

To test the hypothesis that football training would be accompanied by physiological adaptations and hormonal changes, we analyzed the effects of a whole football season on physical fitness and hormonal concentrations in youth football players. Male football players (n = 29, age 16.51 ± 0.7 years) in a regional professional league and male healthy control subjects (n = 30, age 17.1 ± 1 years) participated to the study. Blood cortisol, testosterone, and growth hormone (hGH) concentrations were assayed before the beginning of the training period (T0), just after the training period (T1), at the middle of the season (T2), and at the end of the season (T3). In each period physical tests and anthropometric measurements were also performed. Results showed significant differences in basal values of cortisol, testosterone, and growth hormone (hGH) in the four time points evaluated (P < 0.01). In addition, the concentrations of hGH were higher in the soccer players group than in control subjects (P < 0.001). Between the start of the training period and the end of the football season significant differences were observed in the anthropometric characteristics and in the physical form of the football players. Furthermore, the hormonal status was significantly correlated with the indicators of the lower limb power (squat-jump [SqJ], and counter-movement-jump [CMJ]) and those of aerobic performance (Yo–Yo intermittent recovery test level 1 (YYIRT1) and maximal oxygen consumption (VO_2max)).These data underscore the importance of establishing training protocols that present the potential to promote positive adaptations without, at the same time, provoking overtraining of young players.     

Short-term effects of strength and plyometric training on sprint and jump performance in professional soccer players

The purpose of this study was to compare the effects of combined strength and plyometric training with strength training alone on power-related measurements in professional soccer players. Subjects in the intervention team were randomly divided into 2 groups. Group ST (n = 6) performed heavy strength training twice a week for 7 weeks in addition to 6 to 8 soccer sessions a week. Group ST+P (n = 8) performed a plyometric training program in addition to the same training as the ST group. The control group (n = 7) performed 6 to 8 soccer sessions a week. Pretests and posttests were 1 repetition maximum (1RM) half squat, countermovement jump (CMJ), squat jump (SJ), 4-bounce test (4BT), peak power in half squat with 20 kg, 35 kg, and 50 kg (PP20, PP35, and PP50, respectively), sprint acceleration, peak sprint velocity, and total time on 40-m sprint. There were no significant differences between the ST+P group and ST group. Thus, the groups were pooled into 1 intervention group. The intervention group significantly improved in all measurements except CMJ, while the control group showed significant improvements only in PP20. There was a significant difference in relative improvement between the intervention group and control group in 1RM half squat, 4BT, and SJ. However, a significant difference between groups was not observed in PP20, PP35, sprint acceleration, peak sprinting velocity, and total time on 40-m sprint. The results suggest that there are no significant performance-enhancing effects of combining strength and plyometric training in professional soccer players concurrently performing 6 to 8 soccer sessions a week compared to strength training alone. However, heavy strength training leads to significant gains in strength and power-related measurements in professional soccer players.     

The effect of 40-m repeated sprint training on maximum sprinting speed, repeated sprint speed endurance, vertical jump, and aerobic capacity in young elite male soccer players

The purpose of this study was to examine the effect of 10 weeks' 40-m repeated sprint training program that does not involve strength training on sprinting speed and repeated sprint speed on young elite soccer players. Twenty young well-trained elite male soccer players of age (±SD) 16.4 (±0.9) years, body mass 67.2 (±9.1) kg, and stature 176.3 (±7.4) cm volunteered to participate in this study. All participants were tested on 40-m running speed, 10 × 40-m repeated sprint speed, 20-m acceleration speed, 20-m top speed, countermovement jump (CMJ), and aerobic endurance (beep test). Participants were divided into training group (TG) (n = 10) and control group (CG) (n = 10). The study was conducted in the precompetition phase of the training program for the participants and ended 13 weeks before the start of the season; the duration of the precompetition period was 26 weeks. The TG followed a Periodized repeated sprint training program once a week. The training program consisted of running 40 m with different intensities and duration from week to week. Within-group results indicate that TG had a statistically marked improvement in their performance from pre to posttest in 40-m maximum sprint (-0.06 seconds), 10 × 40-m repeated sprint speed (-0.12 seconds), 20- to 40-m top speed (-0.05 seconds), and CMJ (2.7 cm). The CG showed only a statistically notable improvement from pre to posttest in 10 × 40-m repeated sprint speed (-0.06 seconds). Between-group differences showed a statistically marked improvement for the TG over the CG in 10 × 40-m repeated sprint speed (-0.07 seconds) and 20- to 40-m top speed (-0.05 seconds), but the effect of the improvement was moderate. The results further indicate that a weekly training with repeated sprint gave a moderate but not statistically marked improvement in 40-m sprinting, CMJ, and beep test. The results of this study indicate that the repeated sprint program had a positive effect on several of the parameters tested. However, because the sample size in this study is 20 participants, the results are valid only for those who took part in this study. Therefore, we advice to use repeated sprint training similar to the one in this study only in periods where the players have no speed training included in their program. Furthermore, the participants in this study should probably trained strength, however, benefits were observed even without strength training is most likely to be caused by the training specificity.     

Effects of high-intensity sprint training on skeletal muscle blood flow in rats.

The regional blood flow response (via radioactive microspheres) was determined for female rats after 6 wk of high-intensity sprint training (HIST) or limited cage activity as the animals exercised at work loads that would elicit maximal O2 uptake. Blood flow to the different organs of the abdominal region was greatly reduced during maximal exercise conditions, and the magnitude of the reduction appeared to be similar for both the HIST group of rats and their sedentary (SED) control counterparts. Of the 20 different hindlimb muscles examined in the present study, blood flow to the soleus, plantaris, gastrocnemius, flexor hallicus longus, vastus lateralis, rectus femoris, biceps femoris, and adductor magnus and brevis muscles was significantly greater (P less than 0.05) in the HIST rats during maximal exercise conditions than in the SED control rats. Correspondingly, blood flow to the total hindlimb during maximal exercise was also significantly greater in the HIST rats than in the SED control rats [240 +/- 18 vs. 192 +/- 15 (SE) ml.min-1.100 g-1]. These results support the contention that the increase in maximal cardiac output that is produced by HIST in the rat is primarily directed toward the working skeletal muscle and not toward the organs found in the abdominal region. We conclude from these experiments that HIST will produce significant adaptations in central cardiac function and skeletal muscle blood flow in the rat.     

Effects of a resistance training intervention on the strength-deficit of elite young soccer players

The aim of this study was to examine the effects of a traditional resistance training scheme on the relative strength (RS), relative peak-force (RPF), strength deficit (SDef), and vertical jump and sprint abilities in elite young soccer players. Thirty-five under-20 soccer players from two professional clubs were assessed before and after a 4-week competitive period. One team performed 12 sessions of a structured resistance training program and the other maintained their regular soccer-specific training and competitive routines. Resistance training sessions consisted of half-squat and jump-squat exercises at intensities of 30–80% of the one-repetition maximum. Both teams performed pre- and post-measurements in the following order: (1) countermovement jump (CMJ), (2) 20-m sprint, and (3) half-squat one-repetition maximum to determine the RS, RPF, and SDef. A two-way analysis of variance was used to test for group x time interaction among variables. Effect sizes (ES) and 95% confidence intervals (CI) were also calculated. Group x time interactions were demonstrated for RS ([ES [95%CI] = 1.21 [0.57; 1.85], P = 0.001), RPF (ES [95%CI] = 1.18 [0.52; 1.80], P = 0.001), SDef (ES [95%CI] = 0.86 [0.01; 1.71], P = 0.04), and CMJ (ES [95%CI] = 0.64 [0.28; 0.99], P = 0.001); whereas a non-significant interaction was observed for 20-m sprint performance (ES [95%CI] = 0.02 [-0.32; 0.36], P = 0.85). Traditional strength-power oriented training resulted in improved maximum strength performance and CMJ ability but, paradoxically, increased the SDef. As a consequence, stronger athletes are not necessarily able to use greater percentages of their peak-force against relatively lighter loads.     

Effects of dry-land vs. resisted- and assisted-sprint exercises on swimming sprint performances

This study was undertaken to compare the effects of dry-land strength training with a combined in-water resisted- and assisted-sprint program in swimmer athletes. Twenty-one swimmers from regional to national level participated in this study. They were randomly assigned to 3 groups: the strength (S) group that was involved in a dry-land strength training program where barbells were used, the resisted- and assisted-sprint (RAS) group that got involved in a specific water training program where elastic tubes were used to generate resistance and assistance while swimming, and the control (C) group which was involved in an aerobic cycling program. During 12 weeks, the athletes performed 6 training sessions per week on separate days. All of them combined the same aerobic dominant work for their basic training in swimming and running with their specific training. Athletes were evaluated 3 times: before the training program started, after 6 weeks of training, and at the end of the training program. The outcome values were the strength of the elbow flexors and extensors evaluated using an isokinetic dynamometer, and the speed, stroke rate, stroke length, and stroke depth observed during a 50-meter sprint. No changes were observed after 6 weeks of training. At the end of the training period, we observed significant increases in swimming velocity, and strength of elbow flexors and extensors both in the S and RAS groups. However, stroke depth decreased both in the S and RAS groups. Stroke rate increased in the RAS but not in the S group. However, no significant differences in the swimming performances between the S and RAS groups were observed. No significant changes occurred in C. Altogether, programs combining swimming with dry-land strength or with in-water resisted- and assisted-sprint exercises led to a similar gain in sprint performance and are more efficient than traditional swimming training methods alone.     

Effects of small-sided games and high-intensity interval training on physical performance in young female handball players

This study was designed to compare the effectiveness of small-sided handball games in combination with handball training (SSG group) versus high-intensity interval training in combination with handball training (HIIT group) on physical performance of young female handball players during pre-competitive period. Twenty-four young female handball players, who have a 6.17 ± 1.54 years training experience and competition in the national league participated in this study. SSG group (n = 12; age 16.06 ± 0.80 years, body mass 61.27 ± 3.68 kg, body height 1.64 ± 4.7 m, body mass index 22.7 kg/m²) while HIIT group (n = 12; 16.20 ± 1.28 years, body mass 62.46 ± 7.86 kg, body height 1.68 ± 6.8 m, body mass index 22 kg/m²). Both groups applied training programs twice-a-week for 8 weeks. Before and after the training programs physical performances were assessed: Countermovement jump (CMJ), Squat jump (SJ), Sprint on 0–10 m; Sprint on 0–20 m; Sprint on 0–30 m, Throwing medicine ball and total distance covered during the Yo-YoIRT1. After 8 weeks SSG and HIIT groups significantly improved CMJ, SJ, 0–20 m sprint, 0–30 m sprint, throwing medicine ball and Yo-YoIRT1 (p ≤ 0.05). However, significantly greater improvement was achieved in Yo-YoIRT1 (m) in HIIT group (28.40%) than SSG group (17.63%). These results indicate that SSG group and HIIT group equally improve of physical performances (jump, sprint and upper explosive strength) among young female handball players in pre-competitive period.     

Effects of sprint duration and exercise: rest ratio on repeated sprint performance and physiological responses in professional soccer players

The purpose of this study was to examine the physiological effects of different sprint repetition protocols on professional footballers. Of particular interest were the abilities of repeated sprint protocols to induce fatigue to an extent observed during competitive soccer. Six professional soccer players were assessed for fatigue rate and physiological responses of heart rate (HR), blood lactate (BLa), and rating of perceived exertion (RPE) during the performance of 4 repeated sprint drills, each totaling a sprint distance of 600 m. The 4 drills used 15- or 40-m sprints with 1:4 or 1:6 exercise: rest ratios. The 15-m sprint drill with 1:4 exercise:rest ratio induced the greatest fatigue (final sprint time 15% greater than initial sprint time) and greatest physiological responses. The 40-m sprint drill using a 1:4 exercise:rest ratio produced similar BLa and HR responses to the 15-m drill (13-14 mmol.L(-1) and 89% HRmax, respectively) but significantly lower RPE (mean +/- SD: 17.1 +/- 0.4 vs. 18.8 +/- 0.4, p < 0.05) and fatigue rates (11.1 vs. 15.0%, p < 0.01). Both sprint distance and exercise:rest ratio independently influenced fatigue rate, with the 15-m sprint distance and the 1:4 exercise:rest ratio inducing significantly (p < 0.01) greater fatigue than the 40-m sprint distance and the 1:6 exercise:rest ratio. The magnitude of fatigue during the 40- x 15-m sprint drill using a 1:6 exercise:rest ratio was 7.5%, which is close to the fatigue rate previously reported during actual soccer play. The present study is the first to examine both variations in sprint distances and rest ratios simultaneously, and the findings may aid the design of repeated sprint training for soccer.     

The effects of resisted sprint training on acceleration performance and kinematics in soccer, rugby union, and Australian football players

Acceleration is a significant feature of game-deciding situations in the various codes of football. However little is known about the acceleration characteristics of football players, the effects of acceleration training, or the effectiveness of different training modalities. This study examined the effects of resisted sprint (RS) training (weighted sled towing) on acceleration performance (0-15 m), leg power (countermovement jump [CMJ], 5-bound test [5BT], and 50-cm drop jump [50DJ]), gait (foot contact time, stride length, stride frequency, step length, and flight time), and joint (shoulder, elbow, hip, and knee) kinematics in men (N = 30) currently playing soccer, rugby union, or Australian football. Gait and kinematic measurements were derived from the first and second strides of an acceleration effort. Participants were randomly assigned to 1 of 3 treatment conditions: (a) 8-week sprint training of two 1-h sessions x wk(-1) plus RS training (RS group, n = 10), (b) 8-week nonresisted sprint training program of two 1-h sessions x wk(-1) (NRS group, n = 10), or (c) control (n = 10). The results indicated that an 8-week RS training program (a) significantly improves acceleration and leg power (CMJ and 5BT) performance but is no more effective than an 8-week NRS training program, (b) significantly improves reactive strength (50DJ), and (c) has minimal impact on gait and upper- and lower-body kinematics during acceleration performance compared to an 8-week NRS training program. These findings suggest that RS training will not adversely affect acceleration kinematics and gait. Although apparently no more effective than NRS training, this training modality provides an overload stimulus to acceleration mechanics and recruitment of the hip and knee extensors, resulting in greater application of horizontal power.     

Effect of regular training on plasma thiols,malondialdehyde and carnitine concentrations in young soccer players

Physical activity is known to induce oxidative stress in individuals subjected to intense exercise. Contrarily, there are enzymatic and nonenzymatic defence systems against oxygen radicals in aerobic organisms. Sulphydryl groups such as thiol and glutathione (GSH) can be given as an example to non-enzymatic low molecular weight antioxidants. Carnitine may be related to the performance enhancement in high intensity intermittent exercises and might probably improve the aerobic capacity by stimulating lipid oxidation in muscle cells during long term exercise. But, the effects caused by this supplement during physical activity have not been fully described in the literature. The aim of the study was to compare plasma thiols (PSH), malondialdehyde (MDA) and carnitine levels and maximal oxygen uptake (VO2(max)) of the soccers under regular training with the values of the healthy controls. Our results demonstrates that soccers seem to be under less oxidative stress, as their MDA levels were significantly lower (P < 0.001) when compared with the control group while their PSH levels were significantly elevated (P < 0.001), during resting condition. In addition, the plasma carnitine concentrations of the soccer group yields lower values while the VO2(max) yields a higher value when compared with the control group. The differences between the soccer and the control groups are significant (for both, P < 0.001). The present research reveals the fact that regular soccer training shows beneficial effect on decreasing of lipid peroxidation levels. Furthermore; the sportsmen who are under intense training programs have low plasma carnitine values which do not cause negative effect on their sportive performance.     

Effects of self-paced high-intensity interval training and moderate-intensity continuous training on the physical performance and psychophysiological responses in recreationally active young adults

This study aimed to compare the effects of 8-week self-paced high-intensity interval training (HIIT) vs. self-paced moderate-intensity continuous training (MICT) on the physical performance and psychophysiological responses of young adults. Twenty-eight recreationally active young adults (age: 21.1 ± 1.6 years) were randomly assigned to either the self-paced HIIT (n = 14) or the MICT (n = 14) group training protocol. The HIIT consisted of two 12–24 x 30 seconds of high-intensity runs interspersed by 30 seconds of recovery. The MICT completed 24–48 minutes of continuous running. Before and after the 8-week interventions the following tests were completed: maximum oxygen consumption (V̇O_2max) estimated from the Yo-Yo Intermittent Recovery Test level 1 (YYIRTL-1), repeated sprint ability (RSA), 10–30-m sprint test, change of direction test (T-drill), countermovement jump (CMJ) and squat jump (SJ), and triple hop distance test (THD). Training rating of perceived exertion (RPE) and physical activity enjoyment scale (PACES) were assessed during the training programme. The HIIT resulted in greater improvement in YYIRTL-1, V̇O_2max, RSA and T-drill performances compared to the MICT. Furthermore, RPE and PACES values were higher in the HIIT than the MICT. This study suggested that self-paced HIIT may be a more effective training regime to improve aerobic fitness with greater physical enjoyment in recreationally active young adults.     

Effect of training day,match, and length of the microcycle on workload periodization in professional soccer players: a full-season study

The aims of this study were to: (a) describe and compare the volume and intensity from the workload of professional soccer players between training and MD, and (b) analyse the effect that the length of the microcycle had on the workload. A cohort study was designed for a full season in La Liga 123. Wearable tracking systems collected the distance covered in meters (m), total number of high-intensity accelerations (ACC_HIGH) and decelerations (DEC_HIGH), total number of high-speed running actions (HSRA), high-speed running distance (HSRD), high metabolic load distance (HMLD), and player load (PL) from training days (MD+1, MD-4, MD-3, MD-2, and MD-1) and MD. Significant differences were found between training and MD workload, MD workload being the most demanding for all intensity and volume variables (F = 36.35–753.94; p < 0.01; w_p² = 0.21–0.85). The greatest training intensity and volume were found on MD-4 and MD-3 (p < 0.05). In addition, a novel finding was that the length of the microcycle had a significant effect on the workload both in volume and intensity (F = 4.84–14.19; p < 0.01; w_p² = 0.03–0.09), except for relative ACC_HIGH, DEC_HIGH, and HMLD. Although MD-4 and MD-3 were the most suitable days for loading the players, the results showed that MD elicited a unique stimulus in terms of volume and intensity. Consequently, coaches need to include specific training drills to adapt the players for the competitive demands. Finally, special focus should be placed on MD from short and regular microcycles (5-day, 6-day, or 7-day microcycles) since declines in physical performance were observed in comparison with long microcycles (8-day or 9-day microcycles).     

Effects of speed, agility, quickness training method on power performance in elite soccer players

The purpose of this study was to evaluate the effects of the speed, agility, quickness (SAQ) training method on power performance in soccer players. Soccer players were assigned randomly to 2 groups: experimental group (EG; n = 50) and control group (n = 50). Power performance was assessed by a test of quickness--the 5-m sprint, a test of acceleration--the 10-m sprint, tests of maximal speed--the 20- and the 30-m sprint along with Bosco jump tests--squat jump, countermovement jump (CMJ), maximal CMJ, and continuous jumps performed with legs extended. The initial testing procedure took place at the beginning of the in-season period. The 8-week specific SAQ training program was implemented after which final testing took place. The results of the 2-way analysis of variance indicated that the EG improved significantly (p < 0.05) in 5-m (1.43 vs. 1.39 seconds) and in 10-m (2.15 vs. 2.07 seconds) sprints, and they also improved their jumping performance in countermovement (44.04 vs. 4.48 cm) and continuous jumps (41.08 vs. 41.39 cm) performed with legs extended (p < 0.05). The SAQ training program appears to be an effective way of improving some segments of power performance in young soccer players during the in-season period. Soccer coaches could use this information in the process of planning in-season training. Without proper planning of the SAQ training, soccer players will most likely be confronted with decrease in power performance during in-season period.     

4周低氧训练对男子足球运动员有氧耐力与T淋巴细胞亚群的影响

目的：探讨4周低氧训练对男子足球运动员有氧耐力相关指标与免疫系统中T淋巴细胞亚群的影响。方法：选取某体育学院及其附属竞技学校20名男子足球运动员为受试者,平均分为训练组、低氧组、低氧训练组以及对照组。训练组进行每日60 min,每周5次,持续4周的功率自行车训练,运动强度为65%~75%最大摄氧量;低氧组进行持续4周每日60 min,每周5次处于低氧环境（氧浓度为14.7%）,不进行功率自行车训练;低氧训练组在低氧环境（氧浓度为14.7%）下进行与训练组相同条件的训练;对照组不做任何影响。结果：经4周训练后,低氧训练组红细胞计数、血红蛋白含量较对照组、训练组以及低氧组均存在显著性差异（P < 0.05）;低氧训练组VO₂max水平和3 000 m跑成绩较对照组、训练组以及低氧组均存在显著性差异（P < 0.05）;低氧训练组T淋巴细胞CD3⁺水平较对照组、低氧组均存在显著性差异（P < 0.05）。结论：相比于其他方式,每日60 min,每周5日,持续4周的65%~75%最大摄氧量强度低氧训练更有利于提高男子足球运动员的有氧耐力水平,并且可能有利于运动员机体免疫功能的提高。     

Short-term effects of on-field combined core strength and small-sided games training on physical performance in young soccer players

This study aimed to compare the effects of 6-weeks combined core strength and small-sided games training (SSG_core) vs. small-sided games (SSG) training on the physical performance of young soccer players. Thirty-eight amateur soccer players (age: 16.50 ± 0.51 years) were randomly assigned to either a SSG_core (n = 20) or a SSG group (n = 18). The SSG_core group performed upper and lower body core strength exercises combined with SSG including 2-, 3- and 4-a-sided soccer games third a week. The SSG group performed only the SSG periodization. Baseline and after the 6-week training period the Yo-Yo Intermittent Recovery Test level 1 (YYIRTL-1), 5–20-m sprint test, countermovement jump (CMJ), squat jump (SJ), triple-hop distance (THD), zigzag agility with ball (ZAWB) and without ball (ZAWOB), three corner run test (TCRT) and Y-balance test. The SSG_core group demonstrated meaningful improvements in 20 m sprint time (SSG_core: -9.1%, d = 1.42; SSG: -4.4%, d = 0.76), CMJ (SSG_core: 11.4%, d = 2.67; SSG: -7.7%, d = 1.43), SJ (SSG_core: 12.0%, d = 2.14; SSG: 5.7%, d = 1.28), THD (SSG_core: 5.0%, d = 1.39; SSG: 2.7%, d = 0.52) and TCRT (SSG_core: -3.7%, d = 0.69; SSG: -1.9%, d = 0.38). Furthermore, the SSG_core group demonstrated meaningfully higher improvement responses in both leg balance score (d = ranging from 2.11 to 2.75) compared with SSG group. These results suggest that the inclusion of core strength training to a SSG periodization is greatly effective to improve speed and strength-based conditioning in young soccer players.     

Effects of isoinertial or machine-based strength training on performance in tennis players

The objective of this study was to analyze the effects of two 8-week neuromuscular training (NMT) interventions on selected physical indicators in young tennis players. Twenty-four junior male tennis players were assigned to a machine-based (MG) (n = 8), flywheel (FG) (n = 8) or a control training group (CG) (n = 8). Tests at baseline, week 4 and 8 included: countermovement jump (CMJ); speed (S; 5, 10, 15 m); agility (right [AR] and left [AL]); serve velocity (SV) and medicine ball throws (MBT; overhead [O], forehand [FH], backhand [BH]). MG and FG attained large positive effects at week 4 in CMJ, S 10 m; AR, AL and MBT FH only in FG. Regarding inter- to post-test, MG achieved large positive effects in MBT O, FH and both groups in BH. Large negative effects appeared for FG in S 5 and 10 m and AR and AL. Both NMT interventions led to positive effects from baseline to week 4 measures in CMJ, S 5 m, 10 m and agility and at week 8 in MBT. Conducting the same NMT for a longer period of time did not lead to the same improvements and other negative effects in FG appeared. Results indicate that performing these interventions with little exercise variability or load management, especially after technical-tactical sessions, could interpose further beneficial outcomes and initial gains could be impaired.