Skeletal muscle and performance adaptations to high-intensity training in elite male soccer players: speed endurance runs versus small-sided game training.

PURPOSE: To examine the skeletal muscle and performance responses across two different exercise training modalities which are highly applied in soccer training. METHODS: Using an RCT design, 39 well-trained male soccer players were randomized into either a speed endurance training (SET; n = 21) or a small-sided game group (SSG; n = 18). Over 4 weeks, thrice weekly, SET performed 6-10 × 30-s all-out runs with 3-min recovery, while SSG completed 2 × 7-9-min small-sided games with 2-min recovery. Muscle biopsies were obtained from m. vastus lateralis pre and post intervention and were subsequently analysed for metabolic enzyme activity and muscle protein expression. Moreover, the Yo-Yo Intermittent Recovery level 2 test (Yo-Yo IR2) was performed. RESULTS: Muscle CS maximal activity increased (P < 0.05) by 18% in SET only, demonstrating larger (P < 0.05) improvement than SSG, while HAD activity increased (P < 0.05) by 24% in both groups. Na(+)-K(+) ATPase α1 subunit protein expression increased (P < 0.05) in SET and SSG (19 and 37%, respectively), while MCT4 protein expression rose (P < 0.05) by 30 and 61% in SET and SSG, respectively. SOD2 protein expression increased (P < 0.05) by 28 and 37% in SET and SSG, respectively, while GLUT-4 protein expression increased (P < 0.05) by 40% in SSG only. Finally, SET displayed 39% greater improvement (P < 0.05) in Yo-Yo IR2 performance than SSG. CONCLUSION: Speed endurance training improved muscle oxidative capacity and exercise performance more pronouncedly than small-sided game training, but comparable responses were in muscle ion transporters and antioxidative capacity in well-trained male soccer players

Change of direction asymmetry across different age categories in youth soccer

Background In youth, the development of change of direction (COD) and sprint performance is a key component for successfully competing in soccer across age. During a COD, the presence of directional asymmetries may be detrimental due to the unpredictable nature of the sport. Therefore, the aims of the study were to investigate asymmetries in COD ability and to examine the differences in COD and sprint performance across age in young soccer players. Methods Sixty-eight sub-elite soccer players of different age categories (U18, U17, U16, U15) were tested on a 10-m linear sprint test and 90°COD (5-m entry and exit) test in both directions. Asymmetric index (AI) of COD deficit was obtained for dominant (fastest) and non-dominant directions (slowest). Results The results showed that U16 were more asymmetrical than U18, U17, and U15 from large to moderate effects. The sprint time improved linearly across age with U18 and U15 displaying the fastest and slowest 10-m sprint performance (p 0.05). Conclusion Given the results of this study, practitioners are encouraged to assess asymmetries between dominant and non-dominant directions rather than solely players’ COD ability in young soccer players

Accuracy comparison of the new and previous kodex occlusion tool software versions to assess pulmonary vein occlusion in atrial fibrillation cryoablation

Abstract Funding Acknowledgements Type of funding sources: None. Background. Atrial fibrillation (AF) is the most frequent sustained arrhythmia worldwide and Cryoballoon ablation (CB) has become a consolidated alternative to the radiofrequency pulmonary vein (PV) isolation. However, CB requires fluoroscopy and dye injections to verify the occlusion grade. The accuracy of the earlier version of the Kodex Occlusion Tool software has been studied. Purpose. The purpose of this study was to verify the accuracy of the second generation Kodex Occlusion Tool Software of a new dielectric system imaging compared to its first generation to detect PV occlusion during CB ablation in patients with AF. Methods. 15 consecutive patients with paroxysmal AF were enrolled in the study and underwent the procedure with the guidance of the first generation version (1.4.6) of the Kodex Occlusion Tool software. The Kodex recorded procedural data were used to replay the case using the Kodex second generation version (1.4.7) of the Occlusion Tool software when clinically available. After transseptal access, a detailed image reconstruction of left atrium and PVs was achieved with an octa-polar circular mapping catheter, PV occlusion was assessed with the Occlusion Tool Software and compared with standard dye injection and angiography, the cryoablation was then performed with a cryoballoon catheter. Results. A total of 72 PVs CB occlusions were tested. The old version showed 90.7% sensitivity and 76.5% specificity in assessing a complete PV occlusion verified with contrast medium injection. The positive predictive value was 80.3%, and the negative predictive value was 88.6%. The new version showed 94.8% sensitivity and 93.7% specificity in assessing a complete PV occlusion verified with same contrast medium injection data. The positive predictive value was 98.2%, and the negative predictive value was 93.7%. Acute isolation was achieved in all PVs and no 30-day complication was observed. Conclusion. This study demonstrates an increased accuracy of new Occlusion Tool software of the Kodex dielectric imaging system to assess the degree of PV occlusion during a CB ablation. Abstract Figure. Occlusion tool software 1.4.6 vs 1.4.7 </jats:sec

Running intensity fluctuations indicate temporary performance decrement in top-class football

Match analyses were performed on 473 top-class male footballers. Distances covered during peak-distance 1-, 2- and 5-min periods of a game were 98 ± 5, 135 ± 8 and 235 ± 13 m at speeds &gt;14 km·h −1. In the 5-min period following peak-distance 1-, 2- and 5-min periods, players had a high-intensity running distance deficit (P &lt; 0.05) of 21, 18 and 17 m, respectively, compared to average 5-min distance. High-intensity running distances covered in peak-distance 5- and 1-min periods were greater (P &lt; 0.05) for all playing positions other than central defender. In the 5-min period following the peak-distance 5-min period, less (P &lt; 0.05) high-intensity distance was covered for all playing positions than in the average 5-min period. Distances covered by substitutes during the last 15 min of a game at speeds &gt;11-&gt;24 km·h −1 were greater (18–39%; P &lt; 0.05) compared to full-game players. In 5-min period following peak-distance 1-, 2- and 5-min periods, substitutes performed 9–21% less high intensity running than on average. In conclusion, peak-distance 1-, 2- and 5-min periods in a top-class football game reduce high-intensity running distance in the following 5-min period for all playing positions in both full-game players and substitutes. Thus, these short-term periods of a game may induce temporary performance decrement in top-class football players. </p

A novel ventricular map of electrograms duration as a method to identify areas of slow conduction during ablation of ventricular tachycardia

Abstract Funding Acknowledgements Type of funding sources: None. Background – Wave front inhomogeneous propagation is crucial for reentry circuit generation. Bipolar EGM duration is indicative of local conduction delay and may identify areas of low conduction as a functional substrate. This study aimed to create a map of EGM duration during the VT (VEDUM Map) to identify the area of the slowest conduction and to verify if RF delivery at this area allows to rapidly interrupt the VT. Methods – 24 high-density VTs maps (21 patients) were analyzed. Activation maps and voltage maps during SR were performed. An offline remap confirmed with MathLab software was customized to visualize the longest duration electrogram during VT. Results – All of the VTs were interrupted during the first RF delivery (mean time 7,3 ± 5,4 sec (range 3-25 sec)) at the area with the longest EGM duration (212 ± 47 ms (range 113-330 ms)). . In 9 pts (37,5%) the longest EGM was located at the entrance or exit area of the activation maps while in 5 pts (21%) the EGM covered the full diastolic phase. Finally, in 10 pts the longest EGM occurred in the mid-exit-diastolic phase. Conclusions - A novel Ventricular map of Electrograms DUration (VEDUM Map) is highly accurate in defining a conductive vulnerable zone of the VT circuit. The longest EGM duration within the isthmus is highly predictive of rapid VT termination. Quantitative variablesQualitative variablesMeanMedianStandard DeviationAge71738.40BMI26.624.54.02LV EDV16315442.7LV EDD61.2629.9LV EF38.7369.74VT cycle lenght (TCL)35537556.4EGM max. duration in VT21220847EGM max dur / TCL58.260.512Maximum EGM duration localization in CLProto = 12.5%Meso = 33.3%Tele = 25%Full = 20.8%Myocardium voltage characteristics in VEDUM EGMHealthy = 25%Transition = 20.8%Scar = 41.7%Critical Isthmus area12.3107.3VT Interruption during RFYes = 79.2%No = 20.8%Time (seconds) to interruption765Access typeEndo = 58.3%Epi = 29.2%Clinical and procedural dataAbstract Figure. </jats:sec

Effects of traditional balance and slackline training on physical performance and perceived enjoyment in young soccer players

The aim of this study was to evaluate the effects of 12-week balance and slackline training programs on physical performance and perceived enjoyment scale in young soccer players. Forty-one preadolescent soccer players were assigned to two experimental groups performing traditional balance (BLT) or slackline training (SLT), and a control group. Pre-post assessment encompassed Balance Error Scoring System (BESS), Star Excursion Balance test (SEBT), sprint with 90° turns (S90), and countermovement jump (CMJ). The rate of perceived enjoyment scale (PACES) was applied at the end of the experimental period. SLT and BLT improved similarly in BESS, SEBT and S90. No changes were detected in the CMJ. Regarding PACES score, SLT presented significantly higher values than BLT. Young athletes may benefit from a motivating training approach, thus, a designed program based on slackline drills should be preferable to improve physical performance in terms of balance and change of direction ability in preadolescent soccer players. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group

Effects of 12 Weeks High-Intensity & Reduced-Volume Training in Elite Athletes

It was investigated if high-intensity interval training (HIT) at the expense of total training volume improves performance, maximal oxygen uptake and swimming economy. 41 elite swimmers were randomly allocated to a control (CON) or HIT group. For 12 weeks both groups trained ∼12 h per week. HIT comprised ∼5 h vs. 1 h and total distance was ∼17 km vs. 35 km per week for HIT and CON, respectively. HIT was performed as 6-10×10-30 s maximal effort interspersed by 2–4 minutes of rest. Performance of 100 m all-out freestyle and 200 m freestyle was similar before and after the intervention in both HIT (60.4±4.0 vs. 60.3±4.0 s; n = 13 and 133.2±6.4 vs. 132.6±7.7 s; n = 14) and CON (60.2±3.7 vs. 60.6±3.8 s; n = 15 and 133.5±7.0 vs. 133.3±7.6 s; n = 15). Maximal oxygen uptake during swimming was similar before and after the intervention in both the HIT (4.0±0.9 vs. 3.8±1.0 l O(2)×min(−1); n = 14) and CON (3.8±0.7 vs. 3.8±0.7 l O(2)×min(−1); n = 11) group. Oxygen uptake determined at fixed submaximal speed was not significantly affected in either group by the intervention. Body fat % tended to increase (P = 0.09) in the HIT group (15.4±1.6% vs. 16.3±1.6%; P = 0.09; n = 16) and increased (P<0.05) in the CON group (13.9±1.5% vs. 14.9±1.5%; n = 17). A distance reduction of 50% and a more than doubled HIT amount for 12 weeks did neither improve nor compromise performance or physiological capacity in elite swimmers