Latest research in football - week 27 - 2014

#1 Affective decision-making and tactical behavior of under-15 soccer players
Reference: PLoS One. 2014 Jun 30;9(6):e101231. doi: 10.1371/journal.pone.0101231. eCollection 2014.
Authors: Gonzaga Ados S, Albuquerque MR, Malloy-Diniz LF, Greco PJ, Teoldo da Costa I
Download link: http://www.plosone.org/article/fetchObject.action?uri=info%3Adoi%2F10.1371%2Fjournal.pone.0101231&representation=PDF
Summary: Affective decision-making is a type of Executive Function related to cost benefit analysis in situations where gains and losses imply direct consequences for the subject. The purpose of this study was to explore the influence of the affective decision-making on tactical behavior in soccer players under the age of 15 years old. The System of Tactical Assessment in Soccer (FUT-SAT) was used to assess tactical behavior. To evaluate affective decision-making, we used the neuropsychological test called The Iowa Gambling Task (IGT). The values of the offensive, defensive and game tactical behavior of participants were used to create performance groups. The low (≤25%) and high (≥75%) groups, according to offensive, defensive and game tactical behavior, were compared and shown to be different. The values of the IGT net score of the participants with low and high tactical behavior were compared using the non-parametric Mann-Whitney test. Statistically significant differences between the groups were observed for Defensive Tactical Behavior (Z = -3.133; p = 0.002; r = -0.355) and Game Tactical Behavior (Z = -2.267; p = 0.023; r = -0.260). According to these results, it is possible to state that affective decision-making can influence the tactical behavior of under-15 soccer players.


#2 High-intensity intermittent training in hypoxia: a double-blinded, placebo-controlled field study in youth football players
Reference: J Strength Cond Res. 2014 Jun 24. [Epub ahead of print]
Authors: Brocherie F, Girard O, Faiss R, Millet GP.
Summary: This study examined the effects of 5 weeks (∼60 min/training, 2 days/week) of run-based high-intensity, repeated-sprint ability and explosive strength / agility / sprint training in either normobaric hypoxia (RSH; FIO2 14.3%) or in normoxia (RSN; FIO2 21.0%) on physical performance in 16 highly-trained, under-18 male footballers. For both RSH (n = 8) and RSN (n = 8) groups, lower limb explosive power, sprinting (10 to 40 m) times, maximal aerobic speed, repeated-sprint (10 x 30 m, 30-s rest) and repeated-agility (6 x 20 m, 30-s rest) abilities were evaluated in normoxia before and after supervised training. Lower limb explosive power (+6.5±1.9% vs. +5.0±7.6% for RSH and RSN, respectively; both P<0.001) and performance during maximal sprinting increased (from -6.6±2.2% vs. -4.3±2.6% at 10 m to -1.7±1.7% vs. -1.3±2.3% at 40m for RSH and RSN, respectively; P values ranging from <0.05 to <0.01) to a similar extent in RSH and RSN. Both groups improved best (-3.0±1.7% vs. -2.3±1.8%; both P<0.05) and mean (-3.2±1.7%, P<0.01 vs. -1.9±2.6%, P<0.05 for RSH and RSN, respectively) repeated-sprint times, while sprint decrement did not change. Significant interactions effects (P<0.05) between condition and time were found for repeated-agility ability related-parameters with very likely greater gains (P<0.05) for RSH than RSN (initial sprint: 4.4±1.9% vs. 2.0±1.7% and cumulated times: 4.3±0.6% vs. 2.4±1.7%). Maximal aerobic speed remained unchanged throughout the protocol. In youth highly-trained football players, the addition of ten repeated-sprint training sessions performed in hypoxia vs. normoxia to their regular football practice over a 5-week in-season period was more efficient at enhancing repeated-agility ability (including direction changes), while it had no additional effect on improvements in lower limb explosive power, maximal sprinting and repeated-sprint ability performance.


#3 Carbohydrate Ingestion Before and During Soccer Match Play and Blood Glucose and Lactate Concentrations
Reference: J Athl Train. 2014
Authors: Russell M, Benton D., Kingsley M
Summary: The ingestion of carbohydrate (CHO) before and during exercise and at halftime is commonly recommended to soccer players for maintaining blood glucose concentrations throughout match play. However, an exercise-induced rebound glycemic response has been observed in the early stages of the second half of simulated soccer-specific exercise when CHO- electrolyte beverages were consumed regularly. Therefore, the metabolic effects of CHO beverage consumption throughout soccer match play remain unclear. Objective: To investigate the blood glucose and blood lactate responses to CHOs ingested before and during soccer match play. Design: Crossover study. Setting: Applied research study. Patients or Other Participants: Ten male outfield academy soccer players (age ¼ 15.6 6 0.2 years, height ¼ 1.74 6 0.02 m, mass ¼ 65.3 6 1.9 kg, estimated maximal oxygen consumption ¼ 58.4 6 0.8 mL kg 1 min 1 ). Intervention(s): Players received a 6% CHO-electrolyte solution or an electrolyte (placebo) solution 2 hours before kickoff, before each half (within 10 minutes), and every 15 minutes throughout exercise. Blood samples were obtained at rest, every 15 minutes during the match (first half: 0–15, 15–30, and 30–45 minutes; second half: 45–60, 60–75, and 75–90 minutes) and 10 minutes into the halftime break.  Main Outcome Measure(s): Metabolic responses (blood glucose and blood lactate concentrations) and markers of exercise intensity (heart rate) were recorded.  Results: Supplementation influenced the blood glucose response to exercise (time 3 treatment interaction effect: P .05), such that glucose concentrations were higher at 30 to 45 minutes in the CHO than in the placebo condition. However, in the second half, blood glucose concentrations were similar between conditions because of transient reductions from peak values occurring in both trials at halftime. Blood lactate concentrations were elevated above those at rest in the first 15 minutes of exercise (time-of-sample effect: P , .001) and remained elevated throughout exercise. Supplementation did not influence the pattern of response (time 3 treatment interaction effect: P¼ .49). Conclusions: Ingestion of a 6% CHO-electrolyte beverage before and during soccer match play did not benefit blood glucose concentrations throughout the second half of exercise


#4 The impact of neuromuscular electrical stimulation on recovery after intensive, muscle damaging, maximal speed training in professional team sports players
Reference: Journal of Science and Medicine in Sport xxx (2014) xxx–xxx
Authors: Taylor T, West DJ, Howatson G, Jones C, Bracken RM, Love TD, Cook CJ, Swift E, Baker JS, Kilduff LP
Summary: During congested fixture periods in team sports, limited recovery time and increased travel hinder the implementation of many recovery strategies; thus alternative methods are required. We examined the impact of a neuromuscular electrical stimulation device on 24-h recovery from an intensive training session in professional players. Twenty-eight professional rugby and football academy players completed this randomised and counter-balanced study, on 2 occasions, separated by 7 days.
 After baseline perceived soreness, blood (lactate and creatine kinase) and saliva (testosterone and cortisol) samples were collected, players completed a standardised warm-up and baseline coun- termovement jumps (jump height). Players then completed 60m×50m maximal sprints, with 5min recovery between efforts. After completing the sprint session, players wore a neuromuscular electrical stimulation device or remained in normal attire (CON) for 8 h. All measures were repeated immediately, 2 and 24-h post-sprint. Player jump height was reduced from baseline at all time points under both conditions; however, at 24-h neuromuscular electrical stimulation was significantly more recovered (mean ± SD; neuromus- cular electrical stimulation −3.2±3.2 vs. CON −7.2±3.7%; P<0.001). Creatine kinase concentrations increased at all time points under both conditions, but at 24-h was lower under neuromuscular electrical stimulation (P < 0.001). At 24-h, perceived soreness was significantly lower under neuromuscular elec- trical stimulation, when compared to CON (P = 0.02). There was no effect of condition on blood lactate, or saliva testosterone and cortisol responses (P > 0.05). Neuromuscular electrical stimulation improves recovery from intensive training in pro- fessional team sports players. This strategy offers an easily applied recovery strategy which may have particular application during sleep and travel.