Three days of static stretching within a warm-up does not affect repeated-sprint ability in youth soccer players.

This study aimed to examine the repeated-sprint ability (RSA) in soccer players after 3 days of static stretching. Twenty soccer players (age: 16.8 ± 0.4 years) participated in 2 series of experiments with within-subject repeated-measure design (control series [CON]: 13-minute aerobic warm-up; and static-stretching series [SS]: 10-minute aerobic warm-up and 3-minute static stretching). Each series consisted of 5 days, and RSA (9 × 30 m separated by 25-second passive recovery) was tested on days 1 and 5. Static stretching was performed for 3 consecutive days from days 2-4, before and after intermittent aerobic endurance exercise on each day. The same warm-up protocol was used before and after all RSA tests and exercises within 1 series. No significant difference between CON and SS was observed (p > 0.05) in RSA for overall (all sprints), early phase (first to third sprints), middle phase (fourth to sixth sprints), and final phase (seventh to ninth sprints). Short-term static stretching had trivial effects (Cohen's d < 0.35) on overall and split RSA phases (early, middle, and final). The present study showed that performing static stretching for 3 consecutive days and before repeated-sprint test did not negatively affect RSA. However, it is premature to recommend that static stretching could be included in in-season daily warm-up routine because some movements such as jump and single sprint were more sensitive to static stretching.

Effect of preseason concurrent muscular strength and high-intensity interval training in professional soccer players.

This study examined the effect of concurrent muscular strength and high-intensity running interval training on professional soccer players' explosive performances and aerobic endurance. Thirty-nine players participated in the study, where both the experimental group (EG, n = 20) and control group (CG, n = 19) participated in 8 weeks of regular soccer training, with the EG receiving additional muscular strength and high-intensity interval training twice per week throughout. Muscular strength training consisted of 4 sets of 6RM (repetition maximum) of high-pull, jump squat, bench press, back half squat, and chin-up exercises. The high-intensity interval training consisted of 16 intervals each of 15-second sprints at 120% of individual maximal aerobic speed interspersed with 15 seconds of rest. EG significantly increased (p < or = 0.05) 1RM back half squat and bench press but showed no changes in body mass. Within-subject improvement was significantly higher (p < or = 0.01) in the EG compared with the CG for vertical jump height, 10-m and 30-m sprint times, distances covered in the Yo-Yo Intermittent Recovery Test and maximal aerobic speed test, and maximal aerobic speed. High-intensity interval running can be concurrently performed with high load muscular strength training to enhance soccer players' explosive performances and aerobic endurance.

Effects of 12-week on-field combined strength and power training on physical performance among U-14 young soccer players.

This study examined the effects of on-field combined strength and power training (CSPT) on physical performance among U-14 young soccer players. Players were assigned to experimental (EG, n = 28) and control groups (CG, n = 23). Both groups underwent preseason soccer training for 12 weeks. EG performed CSPT twice a week, which consisted of strength and power exercises that trained the major muscles of the core, upper, and lower body. CSPT significantly (p < 0.05) improved vertical jump height, ball-shooting speed, 10 m and 30 m sprint times, Yo-Yo intermittent endurance run (YYIER), and reduced submaximal running cost (RC). CSPT had moderate effect on vertical jump, ball-shooting, 30 m sprint, and YYIER, small effect on 10 m sprint, RC, and maximal oxygen uptake. YYIER had significant (p < 0.05) correlations with 10 m (r = -0.47) and 30 m (r = -0.43) sprint times, ball-shooting speed (r = 0.51), and vertical jump (r = 0.34). The CSPT can be performed together with soccer training with no concomitant interference on aerobic capacity and with improved explosive performances. In addition, it is suggested that CSPT be performed during the preseason period rather than in-season to avoid insufficient recovery/rest or overtraining.

Relationship between anthropometric and physiological characteristics in youth soccer players.

This study examined the relationship between anthropometric and physiological performances among youth soccer players and the positional differences for these variables. Seventy U14 male soccer players (goalkeeper: 10, defender: 20, midfielder: 25, and forward: 15) participated in this study. Body mass was significantly (p < 0.05) correlated with ball shooting speed (r = 0.58) and 30 m sprint time (r = -0.54). Body height was significantly (p < 0.05) correlated with vertical jump height (r = 0.36), 10 m (r = -0.32) and 30 m (r = -0.64) sprint times, Yo-Yo intermittent endurance run (YYIER) distance (r = 0.26), and running time during maximal oxygen uptake (Vo2max) (r = 0.35). Body mass index (BMI) was significantly (p < 0.05) correlated with ball shooting speed (r = 0.31), 30 m sprint time (r = -0.24), Hoff test dribble distance (r = -0.29), YYIER distance (r = -0.25), submaximal running cost (r = -0.38), Vo2max (r = -0.42), and the corresponding running time (r = -0.24). Significant positional differences were observed in anthropometry (body mass [p < 0.01], height [p < 0.01], and BMI [p < 0.01]) but not in physiological performances. This study provides a scientific rationale behind the coaches' practice of selecting young soccer players according to their anthropometry for short-term benefits such as heavier players for higher ball shooting speed and 30-m sprint ability as an example. However, this does not justify such practice in the long-term process of player development.

Higher plantar pressure on the medial side in four soccer-related movements.

OBJECTIVE: To measure the plantar pressure in four soccer-related movements in 15 male soccer players (mean (SD) age 20.9 (1.3) years, height 173 (4) cm, weight 61.7 (3.6) kg). DESIGN: To record plantar pressure distribution, the players wore soccer boots with 12 circular studs and with an insole pressure recorder device equipped with 99 sensors. Plantar pressure was recorded in five successful trials in each of the four soccer-related movements: running, sideward cutting, 45 degrees cutting and landing from a vertical jump. Each footprint was divided into 10 recorded areas for analysis. RESULTS: Compared with running at 3.3 m/s, maximal speed sideward cutting and 45 degrees cutting induced higher peak pressure (p<0.05) under the second toe, medial forefoot, medial arch and medial heel. The peak pressure of the maximal jump landing was lower under the medial forefoot and lateral forefoot as compared with running (p<0.05). The pressure-time integral showed that sideward cutting and 45 degrees cutting induced higher pressures (p<0.05) than running for all recorded areas, except for the lateral forefoot and the lateral arch. In all the four soccer-related movements, a higher pressure was found on the medial side of the plantar surface as compared with the lateral side. CONCLUSIONS: These data suggest that the medial side of the plantar surface may be more prone to injuries, and that foot orthosis adoption, improved soccer boot design and specific muscle training could be considered to reduce pressure and the subsequent risk of injury.

Difference in plantar pressure between the preferred and non-preferred feet in four soccer-related movements.

OBJECTIVE AND PARTICIPANTS: The present study measured the difference in plantar pressure between the preferred and non-preferred foot in four soccer-related movements in 15 male university soccer players (mean (SD) age 20.9 (1.3) years, mean (SD) height 173 (4) cm and mean (SD) weight 61.7 (3.6) kg). DESIGN: To record plantar pressure distribution, players randomly wore three types of soccer shoes (classical 6-stud and 12-stud, and specially designed 12-stud) embedded with an insole pressure recorder device with 99 sensors, divided into 10 areas for analysis. Plantar pressure was recorded in five successful trials in each of the four soccer-related movements: running (at 3.3 m/s), sideward cutting, 45 degrees cutting and landing from a vertical jump. RESULTS: Plantar pressures of the preferred and non-preferred foot were different in 115 of 120 comparisons. The overall plantar pressure of the preferred foot was higher than that of the non-preferred foot. Specifically, in each of the four movements, higher pressure was found in the preferred foot during the take-off phase, whereas this was found in the non-preferred foot during the landing phase. This would suggest a tendency of the preferred foot for higher motion force and of the non-preferred foot for a greater role in body stabilisation. CONCLUSIONS: The data indicate that the preferred and non-preferred foot should be treated independently with regard to strength/power training to avoid unnecessary injuries. Different shoes/insoles and different muscular strengthening programmes are thus suggested for each of the soccer player's feet.

Cost-effectiveness of Helicobacter pylori "test and treat" for patients with typical reflux symptoms in a population with a high prevalence of H. pylori infection: a Markov model analysis.

OBJECTIVE: Patients with typical reflux symptoms may have underlying peptic ulcer disease (PUD) in a population with a high prevalence of Helicobacter pylori infection. In the present study we sought to compare the cost-effectiveness of the H. pylori "test and treat" strategy with that of empirical proton-pump inhibitor (PPI) therapy and endoscopy in patients with typical reflux and a high prevalence of H. pylori infection. MATERIAL AND METHODS: A Markov model was designed to compare the outcomes of three treatment strategies over 12 months among a hypothetical cohort of patients presenting with typical reflux symptoms. There were four exclusive underlying H. pylori- and PUD-related comorbidities in the hypothetical cohort: (1) H. pylori-related PUD, (2) H. pylori infection without PUD, (3) PUD without H. pylori infection and (4) absence of both PUD and H. pylori infection. The transition probabilities and resource utilization were derived from the literature. Percentage of PUD patients treated, total number of symptom-free patient-years gained and total direct medical cost were estimated. RESULTS: By comparing each strategy individually with the no therapy strategy, it was found that the incremental costs per ulcer treated for H. pylori "test and treat", endoscopy and empirical PPI therapy were USD 1778, USD 1797 and USD 2158, respectively. The results of the model were sensitive to the prevalence of H. pylori infection. CONCLUSIONS: Both the H. pylori "test and treat" and initial endoscopic strategies were shown to be more cost-effective than empirical PPI therapy for treating undiagnosed PUD among patients presenting with typical reflux symptoms. The H. pylori "test and treat" strategy appeared to be only slightly more cost-effective than initial endoscopy in a population with a high prevalence of H. pylori infection.