Latest research in football - week 35 - 2017

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.

Following studies were retrieved for this week:

#1 Resistance training status and effectiveness of low frequency resistance training on upper-body strength and power in highly trained soccer players
Reference: J Strength Cond Res. 2017 Aug 26. doi: 10.1519/JSC.0000000000002202. [Epub ahead of print]
Authors: Hertzog M, Rumpf MC, Hader K
Summary: Soccer is classified as a contact/collision sport with many player-to-player duels. Winning these duels, shielding the ball or fending off an opponent requires upper-body strength and power. Therefore this study aimed, a) to examine the time-related effect of an upper-body RT on maximal strength and power changes in highly trained soccer players, b) to investigate if the resistance-training (RT) status influences these changes throughout a competitive season. Twenty-eight soccer players participated in this study and were divided into an untrained (UG) and a trained (TG) group, according to their RT status. Both groups performed the same upper-body RT once a week, over 30 weeks. Maximal strength (1RM) and maximal power (MP) were assessed before, during and after the competitive season. Both groups significantly improved 1RM and MP over the entire competitive season, with a moderate (TG, 13%) to very large (UG, 21%) magnitude in 1RM and with a small (TG, 8%) to moderate (UG, 13%) magnitude in MP. After the initial 10 weeks of RT, UG presented significant and slightly (1RM) to moderately (MP) greater improvements than TG. For all other time intervals, the between-groups changes in 1RM were rated as similar. For the last 20 weeks of the RT, the change in MP was significantly lower for UG compared to TG. One upper-body RT-session per week will provide sufficient stimulus to enable an almost certain improvement in strength and power throughout a competitive season for all players disregarding their initial RT status.


#2 Fundamental Tactical Principles of Soccer: A Comparison of Different Age Groups
Reference: J Hum Kinet. 2017 Aug 1;58:207-214. doi: 10.1515/hukin-2017-0078. eCollection 2017 Sep.
Authors: Borges PH, Guilherme J, Rechenchosky L, da Costa LCA, Rinadi W
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548168/pdf/hukin-58-207.pdf
Summary: The fundamental tactical principles of the game of soccer represent a set of action rules that guide behaviours related to the management of game space. The aim of this study was to compare the performance of fundamental offensive and defensive tactical principles among youth soccer players from 12 to 17 years old. The sample consisted of 3689 tactical actions performed by 48 soccer players in three age categories: under 13 (U-13), under 15 (U-15), and under 17 (U-17). Tactical performance was measured using the System of Tactical Assessment in Soccer (FUT-SAT). The Kruskal Wallis, Mann-Whitney U, Friedman, Wilcoxon, and Cohen's Kappa tests were used in the study analysis. The results showed that the principles of "offensive coverage" (p = 0.01) and "concentration" (p = 0.04) were performed more frequently by the U-17 players than the U-13 players. The tactical principles "width and length" (p < 0.05) and "defensive unit" (p < 0.05) were executed more frequently by younger soccer players. It can be concluded that the frequency with which fundamental tactical principles are performed varies between the gaming categories, which implies that there is valuation of defensive security and a progressive increase in "offensive coverage" caused by increased confidence and security in offensive actions.


#3 High Speed Running and Sprinting Profiles of Elite Soccer Players
Reference: J Hum Kinet. 2017 Aug 1;58:169-176. doi: 10.1515/hukin-2017-0086. eCollection 2017 Sep.
Authors: Minano-Espin J, Casais L, Lago-Penas C, Gomez-Ruano MA
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548164/pdf/hukin-58-169.pdf
Summary: Real Madrid was named as the best club of the 20th century by the International Federation of Football History and Statistics. The aim of this study was to compare if players from Real Madrid covered shorter distances than players from the opposing team. One hundred and forty-nine matches including league, cup and UEFA Champions League matches played by the Real Madrid were monitored during the 2001-2002 to the 2006-2007 seasons. Data from both teams (Real Madrid and the opponent) were recorded. Altogether, 2082 physical performance profiles were examined, 1052 from the Real Madrid and 1031 from the opposing team (Central Defenders (CD) = 536, External Defenders (ED) = 491, Central Midfielders (CM) = 544, External Midfielders (EM) = 233, and Forwards (F) = 278). Match performance data were collected using a computerized multiple-camera tracking system (Amisco Pro®, Nice, France). A repeated measures analysis of variance (ANOVA) was performed for distances covered at different intensities (sprinting (>24.0 km/h) and high-speed running (21.1-24.0 km/h) and the number of sprints (21.1-24.0 km/h and >24.0 km/h) during games for each player sectioned under their positional roles. Players from Real Madrid covered shorter distances in high-speed running and sprint than players from the opposing team (p < 0.01). While ED did not show differences in their physical performance, CD (p < 0.05), CM (p < 0.01), EM (p < 0.01) and F (p > 0.01) from Real Madrid covered shorter distances in high-intensity running and sprint and performed less sprints than their counterparts. Finally, no differences were found in the high-intensity running and sprint distances performed by players from Real Madrid depending on the quality of the opposition.


#4 The Predictors and Determinants of Inter-Seasonal Success in a Professional Soccer Team
Reference: J Hum Kinet. 2017 Aug 1;58:157-167. doi: 10.1515/hukin-2017-0084. eCollection 2017 Sep.
Authors: Kite CS, Nevill A
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548163/pdf/hukin-58-157.pdf
Summary: The aims of this study were to 1) directly compare the performances of a professional soccer team over three seasons, 2) identify key variables that discriminated between a successful or unsuccessful performance, and 3) identify variables that best predicted success. ANOVA revealed that attempted and completed passes were significantly lower (both p < 0.001) in the most successful season (S1). Additionally, shot effectiveness was significantly less (p < 0.001) in their least successful season (S3) (vs S1 -11.61%; d = 0.735; vs S2 -12.02%; d = 0.760). When the match outcome was considered, they attempted significantly fewer passes when they won (-60.26; p = 0.002; d = -0.729) or drew (-44.87; p = 0.023; d = -0.543) compared to when they lost. The binary logistic regression analysis also retained passing variables. The team should attempt fewer passes, but ensure that more of these passes are completed. With away matches, the effect became more pronounced (β = -0.042, OR = 0.959, p = 0.012). In conclusion, the team should adopt a more direct style of play. They should move the ball into a shooting position with fewer passes and ensure that more shots are on the target.


#5 Effects of Plyometric Training and Beta-Alanine Supplementation on Maximal-Intensity Exercise and Endurance in Female Soccer Players
Reference: J Hum Kinet. 2017 Aug 1;58:99-109. doi: 10.1515/hukin-2017-0072. eCollection 2017 Sep.
Authors: Rosas F, Ramirez-Campillo R, Martinez C, Caniuqueo A, Canas-Jamet R, McCrudden E, Meylan C, Moran J, Nakamura FY, Pereira LA, Loturco I, Diaz D, Izquierdo M
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548158/pdf/hukin-58-099.pdf
Summary: Plyometric training and beta-alanine supplementation are common among soccer players, although its combined use had never been tested. Therefore, a randomized, double-blind, placebo-controlled trial was conducted to compare the effects of a plyometric training program, with or without beta-alanine supplementation, on maximal-intensity and endurance performance in female soccer players during an in-season training period. Athletes (23.7 ± 2.4 years) were assigned to either a plyometric training group receiving a placebo (PLACEBO, n = 8), a plyometric training group receiving beta-alanine supplementation (BA, n = 8), or a control group receiving placebo without following a plyometric training program (CONTROL, n = 9). Athletes were evaluated for single and repeated jumps and sprints, endurance, and change-of-direction speed performance before and after the intervention. Both plyometric training groups improved in explosive jumping (ES = 0.27 to 1.0), sprinting (ES = 0.31 to 0.78), repeated sprinting (ES = 0.39 to 0.91), 60 s repeated jumping (ES = 0.32 to 0.45), endurance (ES = 0.35 to 0.37), and change-of-direction speed performance (ES = 0.36 to 0.58), whereas no significant changes were observed for the CONTROL group. Nevertheless, compared to the CONTROL group, only the BA group showed greater improvements in endurance, repeated sprinting and repeated jumping performances. It was concluded that beta-alanine supplementation during plyometric training may add further adaptive changes related to endurance, repeated sprinting and jumping ability.


#6 Baseline Mechanical and Neuromuscular Profile of Knee Extensor and Flexor Muscles in Professional Soccer Players at the Start of the Pre-Season
Reference: J Hum Kinet. 2017 Aug 1;58:23-34. doi: 10.1515/hukin-2017-0066. eCollection 2017 Sep.
Authors: Garcia-Garcia O, Serrano-Gomez V, Hernandez-Mendo A, Morales-Sanchez V
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548152/pdf/hukin-58-023.pdf
Summary: The aim of the study was to determine the mechanical and neuromuscular profile of knee extensor and flexor muscles in professional soccer players at the start of the pre-season, and to calculate percentages for symmetry, as well as examine differences according to the player's positional role. The vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF) and biceps femoris (BF) of 16 professional soccer players were evaluated by means of tensiomyography (TMG) on the first day of the pre-season. A paired-samples t test (p < .05) was used to compare the dominant and non-dominant lower limb. One-way ANOVA was applied, with the positional role as an independent factor. No differences were observed between the dominant and non-dominant leg. The highest degree of symmetry corresponded to the VM (92.5 ± 2.7%), and the lowest to the BF (80.7 ± 10.9%). The positional role was associated with significant differences in some of the variables for the BF, RF and VM, although only the half-relaxation time in the BF and the time to sustain force in the VM differed across all the playing positions considered. TMG was shown to be a useful way of evaluating the neuromuscular characteristics of soccer players at the start of the pre-season, and of establishing baseline values for individual players.


#7 Relationship between Anxiety and Interleukin 10 in Female Soccer Players with and Without Premenstrual Syndrome (PMS)
Reference: Rev Bras Ginecol Obstet. 2017 Aug 28. doi: 10.1055/s-0037-1606244. [Epub ahead of print]
Authors: Foster R, Vaisberg M, Araujo MP, Martins MA, Capel T, Bachi ALL, Bella ZIKJ
Summary: The objective was to investigate the level of anxiety and its relationship with interleukin (IL)-10 (anti inflammatory cytokine that modulates mood swings) in a group of female soccer players. Fifty-two eumenorrheic soccer players were evaluated (age 19.8 ± 4.7 years). The presence of premenstrual syndrome (PMS) and phases of the menstrual cycle were determined by a daily symptom report (DSR) kept for 3 consecutive months. The concentration of cytokine IL-10 was determined from urine samples collected at four moments: at the follicular and luteal phases of the menstrual cycle, and before (pre) and after (post) the simulated game, and it was quantified by flow cytometry (Luminex xMAP - EMD Millipore, Billerica, MA, USA). The level of anxiety was determined through the BAI anxiety questionnaire answered by all athletes at the same time of the urine collection. The Student t-test, analysis of variance (ANOVA) and Pearson correlation with significance level at 5% were used for data analysis.  We showed that the prevalence of PMS among female soccer players is similar to that reported in the literature. In addition, we showed that the group with PMS has a higher level of anxiety compared with group without PMS (p = 0.002). Interleukin-10 analysis in players without PMS revealed that there was a significant decrease in the level of this cytokine before the game during the luteal phase when compared with the follicular phase (p < 0.05). The correlation analysis between IL-10 and anxiety showed a negative correlation post-game in the luteal phase in the group without PMS (p = 0.02; r = -0.50) and a positive correlation post-game in the luteal phase in PMS group (p = 0.04; r = 0.36).  Our results suggest that IL-10 may contribute to reduce anxiety in the group without PMS. This could be attributed to the fact that no IL-10 variation was observed in the group with PMS, which presented higher anxiety symptoms when compared with the group without PMS.


#8 Sprint mechanics return to competition follow-up after hamstring injury on a professional soccer player: A case study with an inertial sensor unit based methodological approach
Reference: J Biomech. 2017 Aug 20. pii: S0021-9290(17)30420-7. doi: 10.1016/j.jbiomech.2017.08.010. [Epub ahead of print]
Authors: Setuain I, Lecumberri P, Izquierdo M
Summary: The present research aimed to describe an inertial unit (IU)-based sprint mechanics evaluation model for assessing players' readiness to return to competition after suffering a grade I hamstring injury. A professional male football player (age 19years; height 177cm; weight 70kg, midfielder, Spanish, 3° Division) with a grade 1 biceps femoris injury was evaluated at pre-season, at return to play after injury and at the end of the competitive season. Sprint mechanics were analyzed via the use of an inertial orientation tracker (Xsens Technologies B.V. Enschede, Netherlands) attached over the L3-L4 region of the subject's lumbar spine. Sprint mechanics such as horizontal components of ground reaction force were assessed in both legs during sprinting actions. Findings and interpretation: Both the coefficient of the horizontal force application (SFV) and the ratio of forces (DRF) applied at increasing velocity were decreased in the injured limb compared with the contralateral healthy limb at the return to play evaluation (73% and 76% reductions, respectively) and returned to symmetrical levels at the end-season evaluation.


#9 The Brazilian World Cup: too hot for soccer?
Reference: Int J Biometeorol. 2017 Aug 25. doi: 10.1007/s00484-017-1425-y. [Epub ahead of print]
Authors: Lucena RL, Steinke ET, Pacheco C, Vieira LL, Betancour MO, Steinke VA
Summary: The main objective of this research was to analyze the climate data for the host cities of the soccer World Cup held in Brazil in June and July 2014. A great deal of criticism was expressed about the Brazilian climate in the national and international press and media in the run-up to the competition, suggesting that the air temperature and relative air humidity would be the main adversaries of the soccer teams, especially those from Europe, during the competition. An analysis of the weather was done at the places and times of each of the 64 matches held. A human thermal comfort index was calculated (discomfort index (DI)) for each of the matches in order to discover the real climatic conditions in the host cities during the 2014 World Cup and their potential influence on the teams and human comfort in general. During the 2014 World Cup, only two matches were played at temperatures above 30 °C, representing a negligible percentage of the total number of matches. The air temperature for over half the matches (53%) was 20-25 °C. The results showed the air temperature and relative humidity data analyzed here both individually and in the form of an index indicate that the World Cup held in Brazil in 2014 did not put any of the players at risk due to extreme heat.



American Football
#1 Prevalence and Impact of Glenoid Augmentation in American Football Athletes Participating in the National Football League Scouting Combine
Reference: Orthop J Sports Med. 2017 Aug 9;5(8):2325967117722945. doi: 10.1177/2325967117722945. eCollection 2017 Aug.
Authors: Knapik DM, Gillespie RJ, Salata MJ, Voos JE
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5555500/pdf/10.1177_2325967117722945.pdf
Summary: Bony augmentation of the anterior glenoid is used in athletes with recurrent shoulder instability and bone loss; however, the prevalence and impact of repair in elite American football athletes are unknown. The purpoas was to evaluate the prevalence and impact of glenoid augmentation in athletes invited to the National Football League (NFL) Scouting Combine from 2012 to 2015. A total of 1311 athletes invited to the NFL Combine from 2012 to 2015 were evaluated for history of either Bristow or Latarjet surgery for recurrent anterior shoulder instability. Athlete demographics, surgical history, imaging, and physical examination results were recorded using the NFL Combine database. Prospective participation data with regard to draft status, games played, games started, and status after the athletes' first season in the NFL were gathered using publicly available databases. Surgical repair was performed on 10 shoulders in 10 athletes (0.76%), with the highest prevalence in defensive backs (30%; n = 3). Deficits in shoulder motion were exhibited in 70% (n = 7) of athletes, while 40% (n = 4) had evidence of mild glenohumeral arthritis and 80% demonstrated imaging findings consistent with a prior instability episode (8 labral tears, 2 Hill-Sachs lesions). Prospectively, 40% (n = 4) of athletes were drafted into the NFL. In the first season after the combine, athletes with a history of glenoid augmentation were not found to be at significant risk for diminished participation with regard to games played or started when compared with athletes with no history of glenoid augmentation or athletes undergoing isolated shoulder soft tissue repair. After the conclusion of the first NFL season, 60% (n = 6 athletes) were on an active NFL roster. Despite being drafted at a lower rate than their peers, there were no significant limitations in NFL participation for athletes with a history of glenoid augmentation when compared with athletes without a history of shoulder surgery or those with isolated soft tissue shoulder repair. Glenohumeral arthritis and advanced imaging findings of labral tearing and Hill-Sachs lesions in elite American football players with a history of glenoid augmentation did not significantly affect NFL participation 1 year after the combine.


#2 Performance and Return to Sport After Clavicle Open Reduction and Internal Fixation in National Football League Players
Reference: Orthop J Sports Med. 2017 Aug 8;5(8):2325967117720677. doi: 10.1177/2325967117720677. eCollection 2017 Aug.
Authors: Jack RA 2nd, Sochacki KR, Navarro SM, McCulloch PC, Lintner DM, Harris JD
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5555514/pdf/10.1177_2325967117720677.pdf
Summary: Clavicle fractures are common injuries in professional football. Surgical fixation of these injuries may lead to decreased nonunion rates, improved shoulder strength, and decreased residual functional impairment. The purpoas of the study was to determine (1) return-to-sport (RTS) rate in National Football League (NFL) players after clavicle fracture open reduction and internal fixation (ORIF), (2) postoperative career length and games per season, (3) pre- and postoperative performance, and (4) postoperative performance compared with control players matched by position, age, years of experience, and performance. Publicly available records were used to identify players who underwent surgical treatment of a clavicle fracture while playing in the NFL. Demographic and performance data were collected for each player, and matched controls were identified. Control and case performance scores were calculated using a standardized scoring system. RTS was defined as playing in 1 NFL game after surgery. Comparisons between case and control groups at preoperative and postoperative time points were made using paired-samples Student t tests. Seventeen surgeries (16 players) were analyzed. Fifteen players (94.1%) were able to RTS in the NFL at a mean 211.3 ± 144.7 days postsurgery; 7 (44%) returned within the same season as their injury and subsequent fixation. The overall rate of a player's remaining in the NFL 1 year after surgery was 88.2%. Players who underwent surgery played in a similar number of games per season and had similar career lengths in the NFL as controls (P > .05). There were no significant (P > .05) differences between cases and matched controls presurgery and preindex. There was no difference (P > .05) in postoperative performance scores or games per season compared with preoperative scores or games per season for any position. Quarterbacks (n = 3, P = .049) and running backs (n = 5, P = .039) had significantly worse postoperative performance scores when compared with postindex matched controls. There is a high rate of RTS in the NFL after clavicle fracture ORIF. Players who underwent clavicle fracture ORIF played in a similar number of games per season and had similar career lengths in the NFL as controls. Quarterbacks and running backs had significantly worse postoperative performance scores when compared with postindex matched controls.


#3 Infographic: Effects of specific injury prevention programmes in football
Reference: Br J Sports Med. 2017 Aug 24. pii: bjsports-2017-098305. doi: 10.1136/bjsports-2017-098305. [Epub ahead of print]
Authors: Thorborg K, Krommes KK, Esteve E, Clausen MB, Bartels EM, Rathleff MS5, Thorborg K


#4 Injuries in Australian Rules Football: An Overview of Injury Rates, Patterns, and Mechanisms Across All Levels of Play
Reference: Sports Health. 2017 Aug 1:1941738117726070. doi: 10.1177/1941738117726070. [Epub ahead of print]
Authors: Saw R, Finch CF, Samra D, Baquie P, Cardoso T, Hope D, Orchard JW
Summary: The nature of Australian rules football (Australian football) predisposes both unique and common injuries compared with those sustained in other football codes. The game involves a combination of tackling, kicking, high-speed running (more than other football codes), and jumping. Two decades of injury surveillance has identified common injuries at the professional level (Australian Football League [AFL]). The objective was to provide an overview of injuries in Australian rules football, including injury rates, patterns, and mechanisms across all levels of play. A narrative review of AFL injuries, football injury epidemiology, and biomechanical and physiological attributes of relevant injuries. The overall injury incidence in the 2015 season was 41.7 injuries per club per season, with a prevalence of 156.2 missed games per club per season. Lower limb injuries are most prevalent, with hamstring strains accounting for 19.1 missed games per club per season. Hamstring strains relate to the volume of high-speed running required in addition to at times having to collect the ball while running in a position of hip flexion and knee extension. Anterior cruciate ligament injuries are also prevalent and can result from contact and noncontact incidents. In the upper limb, shoulder sprains and dislocations account for 11.5 missed games per club per season and largely resulted from tackling and contact. Concussion is less common in AFL than other tackling sports but remains an important injury, which has notably become more prevalent in recent years, theorized to be due to a more conservative approach to management. Although there are less injury surveillance data for non-AFL players (women, community-level, children), many of these injuries appear to also be common across all levels of play. An understanding of injury profiles and mechanisms in Australian football is crucial in identifying methods to reduce injury risk and prepare players for the demands of the game.


#5 Performance and Return to Sport After Forearm Fracture Open Reduction and Internal Fixation in National Football League Players
Reference: Hand (N Y). 2017 Aug 1:1558944717726137. doi: 10.1177/1558944717726137. [Epub ahead of print]
Author: Sochacki KR, Jack RA 2nd, Hirase T, McCulloch PC, Lintner DM, Liberman SR, Harris JD
Summary: Forearm fractures are one of the most common upper extremity injuries requiring surgery in professional football. Surgical fixation of forearm fractures may speed recovery and decrease games missed in football. National Football League (NFL) players who underwent forearm fracture open reduction and internal fixation (ORIF) were identified. Matched controls (position, age, experience, performance) were identified. Control and case performance scores were calculated using a standardized scoring system. Return to sport (RTS) in the NFL was defined as playing in a single NFL game after surgery. Comparisons between case and control groups and preoperative and postoperative time points were made using paired-samples Student t tests. Thirty-six surgeries were analyzed following ORIF. Thirty-three were able to RTS in the NFL at an average of 152.1 + 129.8 days. Controls had a significantly longer NFL career ( P < .001) and played in significantly more games per season ( P = .026) than players who underwent surgery. There was a significant ( P = .013) decrease in games/season for DBs following surgery. No significant difference was seen in postoperative performance scores compared with preoperative scores among any positions, nor in postoperative and postindex performance scores compared with matched controls. There is a high rate of RTS in the NFL following forearm fracture ORIF. Following surgery, players' careers were 1 year shorter and played nearly 2 fewer games per season than matched controls. Games per season following surgery was significantly lower among DBs when compared with presurgery. Postoperative performance scores were not significantly different compared with preoperative and when compared with matched controls.


#6 Sleep-Disordered Breathing and Cardiovascular Correlates in College Football Players
Reference: Am J Cardiol. 2017 Jul 25. pii: S0002-9149(17)31195-5. doi: 10.1016/j.amjcard.2017.07.030. [Epub ahead of print]
Authors: Kim JH, Hollowed C, Irwin-Weyant M, Patel K, Hosny K, Aida H, Gowani Z, Sher S, Gleason P, Shoop JL, Galante A, Clark C, Ko YA, Quyyumi AA, Collop NA, Baggish AL
Summary: This study sought to determine the cardiovascular physiologic correlates of sleep-disordered breathing (SDB) in American-style football (ASF) participants using echocardiography, vascular applanation tonometry, and peripheral arterial tonometry. Forty collegiate ASF participants were analyzed at pre- and postseason time points with echocardiography and vascular applanation tonometry. WatchPAT (inclusive of peripheral arterial tonometry) used to assess for SDB was then performed at the postseason time point. Twenty-two of 40 (55%) ASF participants demonstrated SDB with an apnea-hypopnea index (pAHI) ≥5. ASF participants with SDB were larger (109 ± 20 vs 92 ± 14 kg, p = 0.004) and more likely linemen position players (83% vs 50%, p = 0.03). Compared with those without SDB, ASF participants with SDB demonstrated relative impairments in left ventricular diastolic and vascular function as reflected by lower lateral e' (14 ± 3 vs 17 ± 3 cm/s, p = 0.007) and septal e' (11 ± 2 vs 13 ± 2 cm/s, p = 0.009) tissue velocities and higher pulse wave velocity (5.4 ± 0.9 vs 4.8 ± 0.5 m/s, p = 0.02). In the total cohort, there were significant positive correlations between pAHI and pulse wave velocity (r = 0.42, p = 0.008) and inverse correlations between pAHI and the averaged e' tissue velocities (r = -0.42, p = 0.01). In conclusion, SDB is highly prevalent in youthful collegiate ASF participants and associated with relative impairments in cardiac and vascular function. Targeted efforts to identify youthful populations with SDB, including ASF participants, and implement SDB treatment algorithms, represent important future clinical directives.


#7 Thermoregulatory and Perceptual Effects of a Percooling Garment Worn Underneath an American Football Uniform
Reference: J Strength Cond Res. 2017 Aug 26. doi: 10.1519/JSC.0000000000002207. [Epub ahead of print]
Authors: Keen ML, Miller KC, Zuhl MN
Summary: American football athletes are at the highest risk of developing exertional heat illness (EHI). We investigated whether percooling (i.e., cooling during exercise) garments affected perceptual or physiological variables in individuals exercising in the heat while wearing football uniforms. Twelve males (age=24±4y, mass=80.1±8.5kg, height=182.5±10.4cm) completed this cross-over, counterbalanced study. On day 1, we measured peak oxygen consumption (V[Combining Dot Above]O2). On days 2 and 3, participants wore percooling garments with (ICE) or without (CON) ice packs over the femoral and brachial arteries. They donned a football uniform and completed three, 20-minute bouts of treadmill exercise at ∼50% of peak V[Combining Dot Above]O2 (∼33°C, ∼42% relative humidity) followed by a 10-minute rest period. Ice packs were replaced every 20 minutes. Rating of perceived exertion (RPE), thermal sensation, and thirst sensation were measured before and after each exercise bout. Environmental symptom questionnaire (ESQ) responses and urine specific gravity (Usg) were measured pre-testing and after the last exercise bout. V[Combining Dot Above]O2, change in heart rate (ΔHR), and change in rectal temperature (ΔTrec) were measured every 5 minutes. Sweat rate, sweat volume, and percent hypohydration were calculated. No interactions (F17,187≤1.6, P≥0.1) or main effect of cooling condition (F1,11≤1.4, P≥0.26) occurred for ΔTrec, ΔHR, thermal sensation, thirst, RPE, ESQ, or Usg. No differences between conditions occurred for sweat volume, sweat rate, or percent hypohydration (t11≤0.7, P≥0.25). V[Combining Dot Above]O2 differed between conditions over time (F15,165=3.3, P<0.001); ICE was lower than CON at 30, 55, and 70 minutes (P<0.05). It is unlikely these garments would prevent EHI or minimize dehydration in football athletes.


Australian Football
#1 The relationship between repeated kicking performance and maximal aerobic capacity in elite junior Australian football
Reference: J Strength Cond Res. 2017 Aug 26. doi: 10.1519/JSC.0000000000002220. [Epub ahead of print]
Authors: Joseph J, Woods C, Joyce C
Summary: Australian football (AF) is a physically demanding game, requiring players to engage in a range of anaerobic activities interspersed with prolonged aerobic exercise. Coupled, players have to perform a range of technical skills, the most fundamental of which being to effectively kick (dispose) the ball. The aim of this study was to ascertain the extent to which aerobic capacity influenced kicking performance in AF. Twenty four elite U18 players competing in the same U18 competition performed the Australian Football Kicking test (AFK) three times with the yo-yo IR2 completed twice (between each AFK), with no rest between all three AFKs. Linear mixed models (LMM) reported the extent to which kicking speed and accuracy scores were influenced by the level reached on the yo-yo IR2. Results indicated that players who recorded a higher level on the yo-yo IR2 produced a faster average kicking speed following each AFK (P <0.01), while for all players, kicking speed was faster and more accurate on their dominant kicking leg regardless of score on the yo-yo IR2 (P <0.01). The LMMs also reported that those who maintained kicking speeds following two yo-yo IR2 also had higher competition kicking efficiency than those who reported reduced kicking speeds. These results show that aerobically proficient U18 AF players who attain a relatively higher score on the yo-yo IR2 may be better equipped at preserving their kicking speed. Thus, coaches may wish to integrate both technical and aerobic drills in an attempt to preserve a player's capability to execute ball disposals with a high velocity.


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