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.

Sprint and jump performances in highly trained young soccer players of different chronological age: Effects of linear VS. CHANGE-OF-DIRECTION sprint training.

OBJECTIVE: The aim of this study was to examine the effects of two different sprint-training regimes on sprint and jump performances according to age in elite young male soccer players over the course of one soccer season. METHODS: Players were randomly assigned to two training groups. Group 1 performed systematic change-of-direction sprints (CODST, U19 [n = 9], U17 [n = 9], U15 [n = 10]) while group 2 conducted systematic linear sprints (LST, U19 [n = 9], U17 [n = 9], U15 [n = 9]). Training volumes were similar between groups (40 sprints per week x 30 weeks = 1200 sprints per season). Pre and post training, all players performed tests for the assessment of linear and slalom sprint speed (5-m and 10-m), countermovement jump, and maximal aerobic speed performance. RESULTS: For all physical fitness measures, the baseline-adjusted means data (ANCOVA) across the age groups showed no significant differences between LST and CODST at post (0.061 < p < 0.995; 0.0017 < d < 1.01). The analyses of baseline-adjusted means for all physical fitness measures for U15, U17, and U19 (LST vs. CODST) revealed no significant differences between LST and CODST for U15 (0.213 < p < 0.917; 0.001 < d < 0.087), U17 (0.132 < p < 0.976; 0.001 < d < 0.310), and U19 (0.300 < p < 0.999; 0.001 < d < 0.049) at post. CONCLUSIONS: The results from this study showed that both, LST and CODST induced significant changes in the sprint, lower limbs power, and aerobic performances in young elite soccer players. Since no significant differences were observed between LST and CODST, the observed changes are most likely due to training and/or maturation. Therefore, more research is needed to elucidate whether CODST, LST or a combination of both is beneficial for youth soccer athletes' performance development.

Resistance Training and Handball Players' Isokinetic, Isometric and Maximal Strength, Muscle Power and Throwing Ball Velocity: A Systematic Review and Meta-Analysis.

PURPOSE: Handball (Team Handball) is an intermittent and strenuous contact sport, the successful performance of which depends on frequent body contacts, and the ability to make repeated explosive muscular contractions required for jumping, acceleration, sprinting, turning, changing pace, and throwing a ball. Many studies have investigated the effect of resistance training (RT) in handball players, however with conflicting results. Therefore, our objective was to investigate the impact of RT on maximal strength (isometric and isokinetic strength), the power of both lower and upper limbs, and throwing velocity, in handball players. METHODS: A comprehensive literature search yielded a pool of 18 studies, which were retained in the systematic review and meta-analysis. RESULTS: A total of 275 handball players were included. The overall effect size (ES) of RT was 0.996 ([95%CI 0.827-1.165], p = 0.0000). At the multivariate meta-regression, the effect of publication year was significant, as well as the effects of country, gender, and level. The impact of RT on isokinetic strength was not significant (ES 0.079 [95%CI -0.060-0.219], p = 0.265), whereas the impact of RT on throwing (ES 1.360 [95%CI 0.992-1.728], p = 0.000) was significant, as well as the effects of RT on isometric strength (ES 0.398 [95%CI 0.096-0.700], p = 0.010), on maximal strength (ES 1.824 [95%CI 1.305-2.343], p = 0.000), and on power (ES 0.892 [95%CI 0.656-1.128], p = 0.000). CONCLUSIONS: RT has a significant impact in handball players. Handball coaches could design conditioning protocols and programs based on our results. However, due to a number of shortcomings, including the high, statistically significant heterogeneity among studies and the evidence of publication bias, further high-quality investigations are needed.

Soccer Footedness and Between-Limbs Muscle Strength: Systematic Review and Meta-Analysis.

Purpose: Limb dominance and consequent between-limbs muscle strength in soccer players should be explored to determine a standard musculoskeletal profile to maintain and establish during screening protocols and postinjury rehabilitation. The primary aim of this review was to identify dominant- vs non-dominant-lower-extremity muscle-strength characteristics of healthy soccer players, with secondary aims to consider available between-limbs outcome measures and directions for future research. Methods: Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. Five electronic databases were used for study identification with guidance from a medical librarian. Inclusion criteria consisted of studies employing a cross-sectional design assessing soccer players of all ages, genders, and levels of play that identified limb dominance and associated lower-extremity muscle strength as a main purpose of the experiment. Results: The literature search identified 3471 articles. After screening titles, abstracts, and full texts, 17 articles were included in the review. Peak torques and hamstring-to-quadriceps ratios via isokinetic dynamometry were commonly used, and subsequent meta-analyses were conducted to yield remarkable between-limbs symmetry. Additional results of individual studies also demonstrate symmetry, except 1 article of velocity-dependent measures that reported greater strength in the dominant limb. Conclusions: In soccer, between-limbs muscle strength measured by maximal isokinetic dynamometry demonstrates symmetry across ages, genders, and levels of play. Future testing using alternative measures that more specifically replicate the movement demands of soccer players may further classify between-limbs characteristics.

Stability in post-seasonal hematological profiles in response to high-competitive match-play loads within elite top-level European soccer players: implications from a pilot study.

INTRODUCTION: The stability of hematological status indices is a key determinant of optimal sport performance. The capacity to monitor hematological behaviors of elite soccer players may better explain the stresses placed upon physiological systems and the potential decrements in performance and physical capacity. The primary aim of this investigation was to examine the post-seasonal hematological status of professional top-level soccer players in response to seasonal match-play and training demands, in terms of the training practices, intensity, and loadings that they experience before, during, and after each season. METHODS: Seventeen male elite European soccer players participated in the study (mean±SD: age 26.8±4.6 years, weight 78.1±5.7 kg, height 182.4±4.8 cm, body fat 9.8%±2.9%, and maximal aerobic capacity 56.5±4.2 mL kg-1 min-1). The season culminated in 74 competitive matches including domestic, Champions League, and UEFA Cup matches. Blood samples were collected between 9:00 and 10:30 am after an overnight fast (~10 hours), 72 hours post conclusion of the final match of the competitive season. RESULTS: Near-perfect correlations between white blood cells, neutrophils, the period of season, training availability, and total competitive minutes were found. When adjusting for all the confounding variables, a stability of the hematological profile was noticed. Only mean cell volume and mean cell hemoglobin values were associated with the requirement for elite European soccer teams to fulfill excessive competitive loadings. The reported lower mean cell volume and mean cell hemoglobin values may highlight the accumulative effects of seasonal training and match-play demands. CONCLUSION: Regular blood testing could identify the need for both squad rotation and the implementation of interventions to assist in stabilizing transient hematological behaviors in order to optimize performance and sports output.

Data concerning isometric lower limb strength of dominant versus not-dominant leg in young elite soccer players.

The present data article describes the isometric lower limb strength of dominant leg versus not-dominant leg measured with handheld dynamometer (HHD) in a sample of 31 young elite soccer players (age 16.42 ± 0.45 years; height 169.00 ± 0.50 cm; leg length 94.80 ± 3.32 cm; body-mass 67.04 ± 5.17 kg).

Effects of lunar phases on short-term, explosive physical performance among young trained athletes.

Beliefs that lunar phases affect human physiology started in ancient times. Research has recently revealed that a physical fitness index increased in sedentary students at the new moon (NM) and full moon (FM) compared to other moon phases. However, the effect of lunar cycle (moon illumination and gravitational pull) on physical performance in athletes was not examined. Therefore, this study aimed to evaluate whether short-term explosive performance can be influenced by the different phases of the lunar cycle. Fourteen young male Taekwondo athletes (age: 16.9 ± 0.7 years, height: 159.7 ± 50.6 cm, body mass: 62.85 ± 7.84 kg) performed the following tests to assess the explosive physical performance during the different phases of the lunar cycle (NM, FQ (first quarter), FM, and LQ (last quarter)): maximal isometric manual contraction (dominant hand (MIMCD) and non-dominant hand (MIMCND)), maximal back isometric contraction (MBIC), squat jump (SJ), countermovement jump (CMJ), and 10-m sprint (10 m). The testing sessions during the different moon phases were performed in a counterbalanced order. The order of tests remained the same (MIMCD, MIMCND, MBIC, SJ, CMJ, and 10 m), and all sessions were performed in the evening (6:00 to 8:00 p.m.) on the first day of each evaluated lunar phase. Each parameter was measured over two consecutive lunar months in the calendar. Analysis of variance tests showed that there was no significant effect of lunar cycle on all explosive test measures, p > 0.05. Our results failed to identify any effect of lunar phase on evening explosive performance (mainly involving phosphagen pathway-based efforts) among young trained athletes. Therefore, it appears that moon phase/illumination does not affect short-term physical performance in young trained adolescents.

Implication of dynamic balance in change of direction performance in young elite soccer players is angle dependent?

BACKGROUND: Team sports require rapid whole-body change of direction (COD) in order to regain, maintain possession of the ball or to avoid opponent. These actions are often performed through unilateral process, with the contralateral leg incurring no ground contact. As a result, maintaining unilateral dynamic balance remains important. The aim of this study was to examine the relationship between dynamic balance (DB) and (COD) performance in young elite soccer players. METHODS: Twenty right-footed young elite soccer players (mean age 16.42±0.55 years, mean height 176±2.5 cm; mean leg length 95.70±3.34 cm, mean body mass 67.03±5.20 kg) participated in this study. All players performed star excursion balance test (SEBT) with dominant (DL) and nondominant leg (NDL). Ten-meter sprint with COD of 45°, 90°, 135° or 180° after 5 m were also assessed with COD on both right and left sides. RESULTS: Correlations analysis showed significant negative relationships (moderate to high) between COD tests (with DL and NDL) and some selected reaching directions of the SEBT. Stepwise multiple regression analysis showed that DB performance explained between 20% and 75% of the variance of COD tests. Likewise, dynamic balance contribution was dependent upon the angle of COD and the leg used to turn. CONCLUSIONS: Some selected reaching directions of the SEBT were significantly correlated with COD's performance in young elite soccer players which, possibly due to similarities in movement demands and muscle recruitment. Furthermore, the contribution of dynamic balance on COD performance was angle dependent and individualized specific dynamic stability exercises may be required to compensate players' deficit in each COD angle.

Dynamic balance ability in young elite soccer players: implication of isometric strength.

BACKGROUND: Soccer requires maintaining unilateral balance when executing movement with the contralateral leg. Despite the fact that balance requires standing with maintaining isometric posture with the support leg, currently there is a lack of studies regarding the implication of isometric strength on dynamic balance's performance among young soccer players. Therefore, the aim of this study was to examine the relationship between the Y-Balance Test and 12 lower limbs isometric strength tests. METHODS: Twenty-six right footed soccer players (mean±SD, age=16.2±1.6 years, height=175±4.2 cm, body mass=68.8±6.1 kg) performed a dynamic balance test (star excursion balance-test with dominant- (DL) and nondominant-legs (NDL). Furthermore, maximal isometric contraction tests of 12 lower limb muscle groups were assessed in DL and NDL. RESULTS: Correlations analysis reported a significant positive relationship between some of isometric strength tests (with DL and NDL) and the Y-Balance Test. Furthermore, stepwise multiple regression analysis showed that maximal isometric strength explained between 21.9% and 49.4% of the variance of the Y-Balance Test. Moreover, maximal isometric strength was dependent upon the reaching angle of the Y-Balance Test and the leg used to support body weight. CONCLUSIONS: This study showed a significant implication of maximal isometric strength of the lower limb and the Y-Balance Test. Moreover, the present investigation suggests the implementation of specific lower limb strengthening exercises depending on players' deficit in each reaching direction and leg. This result suggests that further studies should experiment if increasing lower limbs isometric strength could improve dynamic balance ability among young soccer players.

Change of direction ability in young elite soccer players: determining factors vary with angle variation.

BACKGROUND: The ability to change direction is considered of paramount importance in team sports. Currently there is a lack of consensus regarding the most important physical factors that determine change of direction (COD) ability. Therefore, the aim of this study was to examine the relationship between COD ability and targeted selected physical attributes of sprinting, isometric strength and explosive power. METHODS: Thirty-one young elite soccer players (mean±SD, age =17.4±0.6 years, height =177±0.5 cm; leg length =96.9±3.3 cm, body-mass =69.0±6.2 kg) were recruited. A total of eight COD tasks consisting of; a 5-m sprint then a COD of 45°, 90°, 135° or 180° followed by another 5m sprint were performed using dominant (DL) and non-dominant legs (NDL). Physical tests including a 10-m Straight-Line Sprint Test, 12 lower limb isometric strength tests, and jumping tests including: 1) five alternate Leg Jump Test; 2) triple hop distance (DL and NDL); and 3) Standing Broad Jump Test were performed. RESULTS: Stepwise multiple regression analysis showed that the physical attributes explained between 30% and 74% of the variance of the COD performance. Furthermore, these physical attributes were dependent upon COD angle and direction. CONCLUSIONS: The affecting variables of the COD performance differ according to the angle of COD and the leg used to turn. Moreover, isometric strength of the lower-limb muscles represented a major determinant factor of the COD-ability. Consequently, physical fitness coaches should include isometric muscle strengthening exercises in addition to traditional dynamic muscle strength exercises. Moreover, they should implement specific lower limb strength exercises depending on players' deficit in each COD's angles.

Infodemiological data of Ironman Triathlon in the study period 2004-2013.

This article reports data concerning the Internet-related activities and interest for Ironman Triathlon competition. Google Trends (GT) was used and mined from 2004 onwards. The interest for Ironman Triathlon was found to be cyclic over time. The Triathlon-related Internet activities negatively correlated with the number of finishers per year (Pearson׳s correlation r=-0.690, p-value<0.05), while an increasing participation of female athletes who were less likely to surf the Internet could be noticed (r=-0.811, p-value<0.05). Further, younger athletes, who were more likely to access the web, were underrepresented in the Ironman Triathlon event. Moreover, there was a correlation between the biking time and the Internet query volumes (r=0.590, p-value<0.05), and, in particular, for the male athletes (r=0.664, p-value<0.05). Finally, the countries which most contributed to the Internet query volumes were those with the highest number of medals.

Asymmetry of the Modified Illinois Change of Direction Test Impacts Young Elite Soccer Players' Performance.

BACKGROUND: The modified Illinois change of direction test (MICODT) is an asymmetrical test because the numbers of changes of direction performed to the right and to the left are unequal. Therefore, it is possible that the asymmetry of this test may influence agility performance testing. OBJECTIVES: The aim of this study was to compare two opposite/mirrored versions of the modified Illinois change of direction test. PATIENTS AND METHODS: Forty-six right-footed soccer players (17.2 ± 1.6 years-old) participated in the study. Players performed a modified Illinois change of direction test and a mirrored version of this test "inverted modified Illinois change of direction test" (I/MICODT) in a randomized and counter-balanced order. Paired t-test was used to determine whether significant differences existed between time performances of the tests as a within-subjects measure. Players were thereafter stratified into MICODT group or I/MICODT group according to their best performance and independent t-tests were used to determine differences between groups. RESULTS: The analysis revealed no significant difference in time performance between the two versions of test as a within-subjects measure (P > 0.05, ES = 0.05). However, significant better time performances among inverted modified Illinois change of direction group (52% of players) were found when compared to the modified Illinois change of direction group (48% of players) (P < 0.04, ES = 0.66). CONCLUSIONS: The modified Illinois change of direction test must be considered as an asymmetrical test because it underestimates more than half of the players' agility performances. Therefore, fitness coaches should take these results into account when using this test.

Physiological Responses of the Modified Shuttle Test in Adults With Cystic Fibrosis.

PURPOSE: The modified shuttle test (MST) is increasingly used in clinical practice to assess functional capacity in patients with cystic fibrosis (CF). The purpose of this study was to evaluate the physiological responses of the MST in adults with CF as compared with the gold standard cardiopulmonary exercise test (CPET). METHODS: Participants performed an MST and a CPET on a cycle ergometer in random order. Oxygen (O2) uptake ((Equation is included in full-text article.)O2), carbon dioxide (CO2) retention (end-tidal PCO2; PETCO2), minute ventilation, heart rate, and peripheral O2 saturation (SpO2) were continuously monitored. Whole blood lactate, dyspnea, and leg discomfort were recorded immediately after both exercises. RESULTS: Twenty patients with CF (aged 33 ± 8 years; forced expiratory volume in 1 second = 48% ± 17%) completed both tests. Peak values for (Equation is included in full-text article.)O2 (27 ± 7 vs 24 ± 6 mL/kg/min), heart rate (169 ± 19 vs 163 ± 16 bpm), end PETCO2 (42 ± 7 vs 39 ± 8 mm Hg), and O2 desaturation (end SpO2, 86% ± 7% vs 90% ± 6%) were significantly higher during the MST than during the CPET (all Ps < .05). Leg discomfort and whole blood lactate were significantly higher after the CPET (both Ps < .05). Thirty-five percent and 40% of patients showed significant O2 desaturation and CO2 retention, respectively, during the MST, which was not detected during the CPET. A strong relationship was found between MST peak (Equation is included in full-text article.)O2 and body weight walking distance product (r = 0.90; P < .01). CONCLUSIONS: The MST may provide a strong indicator of exercise tolerance in adults with CF as indicated by high peak (Equation is included in full-text article.)O2 values. In clinical practice, body weight walking distance should be considered as the primary outcome. This test is also better than cycle ergometry CPET for detecting O2 desaturation and CO2 retention, further emphasizing its clinical interest.

Effect of leg dominance on change of direction ability amongst young elite soccer players.

Young soccer players often use one particular dominant leg (DL) to perform dynamic movements which require strength, resulting in leg asymmetry. The aim of this study was to compare, in young soccer players, the effect of using DL and non-dominant leg (NDL) on time performance of two change of direction (COD) manoeuvres in several angles of COD. Seventy-three young male soccer players (mean ± SD, age: 16.1 ± 1.8 year) participated in this study. Players performed 10-m sprints, either in a straight line or with a COD (5 m straight ahead and a turn of 45°, 90°, 135° and 180° to the opposite side of the DL or NDL). Testing for COD speed was conducted over two different manoeuvres: (1) sidestepping and (2) bypass. Maximal isometric voluntary contraction of the knee extensors/flexors and hip abductors/adductors was also measured using a handheld dynamometer. For sidestepping, COD performance with use of the DL was significantly better compared to the NDL (P < 0.05) in all angles of COD. However, bypass COD performance through use of the DL was better compared to the NDL only when turning at 135°. Additionally, strength of the knee extensors/flexors and hip abductors of the DL was significantly (P < 0.05) greater than the NDL. The use of the DL allows better COD performance than the NDL when sidestepping manoeuvre is used. However, the DL allows better COD performance than the NDL only at 135° with the use of the bypass manoeuvre. Furthermore, the greater strength of the DL compared to the NDL may contribute to COD performance difference between legs.

The relationship between lower-limb strength and match-related muscle damage in elite level professional European soccer players.

In professional soccer, the benefits of lower limb strength training have been advocated. However, from an aspect of performance development, specifically with respect to expression of fatigue and injury prevention, the advantages of increased lower body strength have received limited attention at the elite level of the game. The primary aim of this cross-sectional investigation was to examine the association between lower body strength and the expression of markers of fatigue as evaluated through muscle damage assessment following match play in professional soccer players. Ten male professional soccer players participated in this investigation (mean ± SD age 26.2 ± 4.3 years, height 181.6 ± 4.8 cm and body mass 78.7 ± 6.1 kg); creatine kinase (CK) was collected 2-days post-match for a 5-month period and at three different time points (Phase 1, Phase 2 and Phase 3); muscular strength (e.g. 4 repetition half-squat) was measured 3-day post-match. No significant change in CK and muscular force across three time points was found (F = 0.60, P = 0.56, η(2) = 0.06 and F = 2.65, P = 0.10, η(2) = 0.23, respectively). Muscular force was negatively correlated (moderate to very large) with CK. It can be concluded that players who produce greater lower body force as a result of being stronger in the lower limbs show reduced levels of CK 48 h post-match.