Latest research in football - week 25 - 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 The provision of medical care in English professional football: An update.
Reference: J Sci Med Sport. 2017 May 25. pii: S1440-2440(17)30430-9. doi: 10.1016/j.jsams.2017.05.004. [Epub ahead of print]
Authors: Malcolm D, Scott-Bell A, Waddington I
Summary: The purpose was to compare the current methods of appointment, qualifications and occupational experience of club doctors and physiotherapists in English professional football with (i) those outlined in a study published in 1999, and (ii) Football Association (FA) medical regulations. Postal questionnaire survey of (head) doctors and physiotherapists at each of the clubs in the English Premiership, Championship and Football Leagues 1 and 2. Response rates of 35.8% and 45.6% respectively were obtained. The majority of football club doctors are GPs who have sports medicine qualifications and relevant occupational experience. Time commitments vary from full time to a few hours per week. Most are appointed through personal contacts rather than job advertisements and/or interview. Almost all football clubs have a chartered physiotherapist, many of whom have a postgraduate qualification. They work full time and long hours. Most are appointed through personal contacts rather than job advertisements. They are frequently interviewed but not always by someone qualified to judge their professional expertise. Football club medical provision has become more extensive and increasingly professional over the last 10-20years, with better qualified, more career-oriented and more formally contracted staff. It is likely that clinical autonomy has subsequently increased. However recruitment procedures still need to be improved, especially in relation to advertising vacancies, interviewing candidates, and including medical personnel on interview panels. In two aspects clubs appear not to be compliant with current FA medical regulations.


#2 Pseudoaneurysm of the Anterior Tibial Artery following Ankle Arthroscopy in a Soccer Player
Reference: Case Rep Orthop. 2017;2017:2865971. doi: 10.1155/2017/2865971. Epub 2017 May 18.
Authors: Tonogai I, Matsuura T, Iwame T, Wada K, Takasago T, Goto T, Hamada D, Kawatani Y, Fujimoto E, Kitagawa T, Takao S, Iwamoto S, Yamanaka M, Harada M, Sairyo K
Summary: Ankle arthroscopy carries a lower risk of vascular complications when standard anterolateral and anteromedial portals are used. However, the thickness of the fat pad at the anterior ankle affords little protection for the thin-walled anterior tibial artery, rendering it susceptible to indirect damage during procedures performed on the anterior ankle joint. To our knowledge, only 11 cases of pseudoaneurysm involving the anterior tibial artery after ankle arthroscopy have been described in the literature. Here we reported a rare case of a 19-year-old soccer player who presented with pseudoaneurysm of the anterior tibial artery following ankle arthroscopy using an ankle distraction method and underwent anastomosis for the anterior tibial artery injury. Excessive distraction of the ankle puts the neurovascular structures at greater risk for iatrogenic injury of the anterior tibial artery during ankle arthroscopy. Surgeons should look carefully for postoperative ankle swelling and pain after ankle arthroscopy.


#3 The effect of air pollution on diurnal variation of performance in anaerobic tests, cardiovascular and hematological parameters, and blood gases on soccer players following the Yo-Yo Intermittent Recovery Test Level-1
Reference: Chronobiol Int. 2017 Jun 14:1-18. doi: 10.1080/07420528.2017.1325896. [Epub ahead of print]
Authors: Boussetta N, Abedelmalek S, Aloui K, Souissi N
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5451781/pdf/CRIOR2017-2865971.pdf
Summary: This study aimed to investigate the effect of air pollution on diurnal variation of performance in anaerobic tests, cardiovascular and hematological parameters, and blood gases on soccer players following the Yo-Yo Intermittent Recovery Test Level-1 (YYIRT1). In a randomized order, 11 healthy soccer players (mean age: 21.8 [range: 20-24] years; height: 178.00 [range: 1.64-1.83] cm; body mass index [BMI]: 23.57 [range: 20.45-28.03] kg.m-2) performed a YYIRT1 at two different times of day (TOD) (08:00 h and 18:00 h) in two areas (i.e. polluted (PA) and non-polluted (NPA)) with a recovery period of ≥ 72 h in between, to determine the maximal oxygen uptake (VO2max). In each test session: resting oral temperature is measured, anaerobic performances (pre- and post-YYIRT1) were performed, cardiovascular parameters and blood samples were collected at: rest, 3 min and 60 min after the YYIRT1, to assess blood gases and hematological parameters. Our results showed that, agility performance, VO2max, red blood cells (RBC), hemoglobin (Hb), pH, and bicarbonate levels (HCO3-) decrease significantly (p < 0.001) following the YYIRT1 in PA compared to NPA. Likewise, the heart rate (HR), systolic blood pressure (SBP), platelets (PLT), white blood cells (WBC), neutrophiles (NEUT), lymphocytes (LYM), and partial pressure of CO2 levels (PvCO2) were significantly higher (p < 0.001) in PA. This effect was slightly accentuated at 18:00 h for some parameters (i.e. Agility, HCO3-, HR, PvCO2, RBC, SBP). However, performances of sprint and Sargent jump test (SJT), oral temperature, rate of perceived exertion scales (RPE), partial pressure of O2 (PvO2), diastolic blood pressure (DBP), and monocytes (MON) were not affected by pollution (p > 0.05). In conclusion, pollution seems to be critical for health stability and performance in response to YYIRT1 especially in the evening and the winter season. Therefore, coaches and athletes should draw attention to the potential importance of land use planning in their training sessions and competitions in the morning in polluted area to minimize the risk of pollution exposure.


#4 The relationship between jumping performance, isokinetic strength and dynamic postural control in elite youth soccer players
Reference: J Sports Med Phys Fitness. 2017 Jun 21. doi: 10.23736/S0022-4707.17.07289-9. [Epub ahead of print]
Authors: Sliwowski R, Grygorowicz M, Wieczorek A, Jadczak L
Summary: The aim of this study was (i) to investigate the relationship between vertical jumping performance, isokinetic strength of knee extensors/flexors, and postural priority and (ii) an attempt to describe a multiple regression model that accounts for the effects of selected parameters of isokinetic strength and postural priority on vertical jumping performance. Thirty-one professional male soccer players, aged from 17 to 20 years, participated in this study (mean age: ± SD 18,6 ± 1.26 years; height: 1,78 ± 0,74 m and weight: 73,1 ± 6,77 kg). The correlations between isokinetic knee strength, jumping performance, and postural control were evaluated using the Pearson correlation coefficient. A linear regression model was used to evaluate the effect of hamstrings and quadriceps peak torque of both legs at 60o·s-1, total work of both legs at 240o·s-1, and postural priority on jumping performance. The peak torque of right leg knee flexor (quadriceps) muscles, evaluated at 60o·s-1 speed, showed correlations with counter movement jump, 30 second jumping and squat jump (p=0.005, p=0.003, and p=0.007, respectively). We also observed a strong relationship between counter movement jump and 30 second jumping and peak torque of left leg evaluated at the same speed of 60o·s-1 (p=0.26 and p=0.22, respectively). No significant correlations were found between any of the jumping tests and peak torque of knee extensors of both legs at 60o·s-1. For the 30 second jumping test, it appears that jumping endurance has a significant relationship with total work of knee flexors for right and left legs at 240o·s-1. The results of this study demonstrate practical implications for soccer performance, but further exploration is required.


#5 Comparison of knowledge, perception and attitudes of concussion in previously concussed versus non-concussed youth soccer players
Reference: Phys Sportsmed. 2017 Jun 21. doi: 10.1080/00913847.2017.1345569. [Epub ahead of print]
Authors: Myrdal CN, Huang S, Beach HN, Waterbrook AL
Summary: The purpose was to examine if history of concussion is correlated with a difference in knowledge, attitude, and perception of concussive injuries in youth soccer players. A convenience sample of youth soccer athletes aged 14 to 18 years completed a survey assessing prior history of concussive injury, knowledge of concussive injury, self-reporting attitudes, and perception of the injury. The survey consists of 16 knowledge questions (eleven on a scale of 1-2, and five on a scale of 1-4) and 12 attitude questions (seven on a scale of 1-4, and five on a scale of 1-5). The primary outcomes are the total scores calculated by summing the standardized raw scores for all knowledge questions and attitude questions, respectively. Linear regression was used to estimate the mean difference in the primary outcomes between previously concussed and non-concussed athletes (calculated as previously concussed - non-concussed). Surveys were obtained from 90 athletes, with 32 (36%) previously sustaining at least one concussion. Thirty-one out of these 32 concussions were diagnosed by a medical provider. On average, the mean total raw scores of all knowledge questions are 34.6 (82.2% of 42 possible points) and 33.7 (80.2% of 42 total points) for previously concussed and non-concussed athletes, respectively, and the mean total raw scores of all attitude questions are 38.7 (72.9% of 53 possible points) and 39.6 (74.7% of 53 possible points), respectively. Mean differences estimated from univariate linear regression in the standardized total scores of knowledge questions and attitude questions are 1.56(95% confidence interval: -1.52-4.65) and -1.23 (%95 confidence interval: -4.64-2.19), respectively. Adjusting for age and years of playing soccer gave similar results. Although we did not find significant differences between previously concussed and non-concussed athletes in either the knowledge or the attitude questions as measured by their total scores, this study showed a high level of awareness of concussion in youth soccer players, while still highlighting a need for education. Limited distinctions were made among subgroups of players, suggesting directions of future research in investigating the role that outside factors may have on knowledge and perception of concussion.


#6 Are Change of Direction Speed and Reactive Agility Useful for Determining the Optimal Field Position for Young Soccer Players?
Reference: J Sports Sci Med. 2017 Jun 1;16(2):247-253. eCollection 2017 Jun.
Authors: Fiorilli G, Iuliano E, Mitrotasios M, Pistone EM, Aquino G, Calcagno G, di Cagno A
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5465987/pdf/jssm-16-247.pdf
Summary: Change Of Direction Speed (CODS) and Reactive Agility (RA) are two determining factors in the ability of young soccer players. We aimed to verify if CODS and RA could be useful in order to establish the best young soccer player field position. Ninety-two elite soccer players (15.18 ± 1.21 years, weight 59.18 ± 9.93, height 1.72 ± 0.08, BMI 19.76 ± 2.22), belonging to two youth categories from the Italian First and Second Divisions, volunteered in this study. The participants included 32 defenders (15.06 ± 0.80 years), 37 midfielders (15.11 ± 0.84 years) and 23 forwards (15.48 ± 1.16 years), and they underwent two tests, each one performed in two different ways: the Y-Agility Test, carried out in a planned and reactive mode (Y-PLAN and Y-REAC), and the Illinois for Change of Direction Test (ICODT) performed with and without the ball. REAC-INDEX, which represents the index of reactivity, was calculated as Y-REAC minus Y-PLAN. The difference between the two scores of ICODT (ICODT with the ball minus ICODT without the ball) represents the TECHN-INDEX. Multivariate Analysis of Variances (MANOVA) was used to evaluate significant differences among all position groups, for all the test scores. MANOVA showed no significant differences in test scores or in TECHN-INDEX among the groups, except for the forwards, who were significantly more reactive than the defenders (p < 0.05). The strong and significant Pearson's Correlation between ICODT with and without the ball (p < 0.01) demonstrated that physical and technical preparations have the same relevance in all positions. No significant differences were found among players in different field positions for CODS and RA performances, both with and without the ball. This study does not recommend to use RA and CODS as indicators to assign the players roles in youth soccer.


#7 Premier League academy soccer players' experiences of competing in a tournament bio-banded for biological maturation
Reference: J Sports Sci. 2017 Jun 19:1-9. doi: 10.1080/02640414.2017.1340656. [Epub ahead of print]
Authors: Cumming SP, Brown DJ, Mitchell S, Bunce J, Hunt D, Hedges C, Crane G, Gross A, Scott S, Franklin E, Breakspear D, Dennison L, White P, Cain A, Eisenmann JC, Malina RM
Summary: Individual differences in the growth and maturation have been shown to impact player performance and development in youth soccer. This study investigated Premier League academy players' experiences of participating in a tournament bio-banded for biological maturation. Players (N = 66) from four professional soccer clubs aged 11 and 14 years and between 85-90% of adult stature participated in a tournament. Players competed in three 11 vs 11 games on a full size pitch with 25-min halves. Sixteen players participated in four 15-min focus groups and were asked to describe their experiences of participating in the bio-banded tournament in comparison to age group competition. All players described their experience as positive and recommended the Premier League integrate bio-banding into the existing games programme. In comparison to age-group competitions, early maturing players described the bio-banded games more physically challenging, and found that they had to adapt their style of play placing a greater emphasis on technique and tactics. Late maturing players considered the games to be less physically challenging, yet appreciated the having more opportunity to use, develop and demonstrate their technical, physical, and psychological competencies. Bio-banding strategies appear to contribute positively towards the holistic development of young soccer players.


#8 Acute Modification of Cardiac Autonomic Function of High-Intensity Interval Training in Collegiate Male Soccer Players with Different Chronotype: A Cross-Over Study
Reference: J Sports Sci Med. 2017 Jun 1;16(2):286-294. eCollection 2017 Jun.
Authors: Bonato M, Agnello L, Galasso L, Montaruli A, Roveda E, Merati G, La Torre A, Vitale JA
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5465992/pdf/jssm-16-286.pdf
Summary: The purpose of this study was to evaluate if the time of the day (8.00 a.m. vs 8.00 p.m.) and chronotype could influence autonomic cardiac control in soccer players in relation to an acute session of high-intensity interval training. The morningness-eveningness questionnaire was administered to recruit Morning-type and Evening-type collegiate male soccer players. Therefore, 24 players (12 Morning-types and 12 Evening-types) were randomly assigned, to either morning (n = 12; age 23 ± 3 years; height 1.75 ± 0.07 m; body mass 73 ± 10 kg; weekly training volume 8 2 hours), or evening (n = 12; age 21 ± 3 years; height 1.76 ± 0.05 m; body mass 75 ± 11 kg; weekly training volume 8 ± 3 hours) training. Heart Rate Variability vagal and sympatho/vagal indices were calculated in time, frequency and complexity domains at rest, before, after 12 and 24 hours of high-intensity interval training. Before evening training session, a higher resting heart rate was observed which was determined by a marked parasympathetic withdrawal with a sympathetic predominance. Moreover, Evening-type subjects during morning training session, present a significant higher heart rate that corresponded to significant higher vagal indices with a significant lower parasympathetic tone that returned to the rest values after 24 hours of the cessation of high-intensity interval training exercise. On the contrary, Morning-type subjects did not reveal any significant differences with Evening-Type subjects during evening high-intensity interval training session. Stress response of high-intensity interval training is influenced by both the time of the day and by the chronotype. Understanding the Heart Rate Variability response to high-intensity interval training can be an additional important procedure for evaluating of cardiovascular recovery in soccer players. Moreover, these results suggest that an athlete's chronotype should be taken into account when scheduling a high-intensity interval training exercise.


#9 Clinical benefit of the FIFA 11 programme for the prevention of hamstring and lateral ankle ligament injuries among amateur soccer players
Reference: Inj Prev. 2017 Jun 22. pii: injuryprev-2016-042267. doi: 10.1136/injuryprev-2016-042267. [Epub ahead of print]
Authors: Nouni-Garcia R, Carratala-Munuera C, Orozco-Beltran D, Lopez-Pineda A, Asensio-Garcia MR, Gil-Guillen VF
Summary: The purpose was to analyse the relationship between the implementation of 'the 11' protocol during the regular season in a men's amateur soccer team and the rate of hamstring and lateral ankle ligament (LAL) injuries, and to estimate the clinical benefit of the programme according to the type of injury and the position field. This cohort study was conducted in two different men's amateur soccer teams. During two seasons, the exposed group (43 players) performed 'the 11' protocol twice a week, and the unexposed group (43 players) performed the regular training programme. All players trained three times per week for 1.5 hours per day. Data collection was performed for every 1000 hours of play. 18 hamstring injuries (injury rate (IR) of 2.26 injuries/1000 training+competition hours) and 15 LAL injuries (IR of 1.88 injuries/1000) were registered in the exposed group. In the unexposed group, there were 25 LAL injuries (IR of 3.14 injuries/1000) and 35 hamstring injuries (IR of 4.39 injuries/1000). The number needed to treat to prevent one new case was 3.9 in LAL injuries, 3.31 in biceps femoris injuries and 10.7 in recurrent hamstring injuries. 'The 11' programme reduced the incidence of hamstring and LAL injuries in amateur players. According to the field position, the programme was effective for defenders and midfielders. In accordance with the type of injury, the exposed group had a lower risk of LAL, biceps femoris and hamstring injuries compared with those in the unexposed group.


#10 Absolute and Relative Training Load and Its Relation to Fatigue in Football
Reference: Front Psychol. 2017 Jun 6;8:878. doi: 10.3389/fpsyg.2017.00878. eCollection 2017.
Authors: Zurutuza U, Castellano J, Echeazarra I, Casamichana D
Summary: The aim of the study was to assess the relationship of external and internal training load (TL) indicators with the objective and subjective fatigue experienced by 15 semi-professional football players, over eight complete weeks of the competition period in the 2015-2016 season, which covered microcycles from 34th to 41st. The maximum heart rate (HRmax) and maximum speed (Vmax) of all the players were previously measured in specific tests. The TL was monitored via questionnaires on rating of perceived exertion (RPE), pulsometers and GPS devices, registering the variables: total distance (TD), player load 2D (PL2D), TD at >80% of the Vmax (TD80), TD in deceleration at < -2 m⋅sec-2 (TDD <-2), TD in acceleration >2 m⋅sec-2 (TDA >2), Edwards (ED), time spent at between 50 and 80% (50-80% HRmax), 80-90% (80-90% HRmax), and >90% of the HRmax (>90% HRmax), and RPE both respiratory/thoracic (RPEres) and leg/muscular (RPEmus). All the variables were analyzed taking into account both the absolute values accumulated over the week and the normalized values in relation to individual mean competition values. Neuromuscular fatigue was measured objectively using the countermovement jump test and subjectively via the Total Quality Recovery (TQR) scale questionnaire. Analytical correlation techniques were later applied within the general linear model. There is a correlation between the fatigue experienced by the player, assessed objectively and subjectively, and the load accumulated over the week, this being assessed in absolute and relative terms. Specifically, the load relative to competition correlated with the physical variables TD (-0.279), PL2D (-0.272), TDD < -2 (-0.294), TDA >2 (-0.309), and sRPEmus (-0.287). The variables related to heart rate produced a higher correlation with TQR. There is a correlation between objectively and subjectively assessed fatigue and the accumulated TL of a player over the week, with a higher sensitivity being shown when compared to the values related to the demands of competition. Monitoring load and assessing fatigue, we are closer to knowing what the prescription of an adequate dose of training should be in order for a player to be as fresh as possible and in top condition for a match. Normalizing training demands with respect to competition could be an appropriate strategy for individualizing player TL.


#11 Effects of structural components of artificial turf on the transmission of impacts in football players
Reference: Sports Biomech. 2017 Feb 24:1-10. doi: 10.1080/14763141.2017.1285347. [Epub ahead of print]
Authors: Encarnacion-Martinez A, Garcia-Gallart A, Gallardo AM, Sanchez-Saez JA, Sanchez-Sanchez J
Summary: The third generation of artificial turf systems (ATS) has matched the mechanical behaviour of natural grass, but today a high heterogeneity at structural level and mechanical behaviour in the new ATS also exists. The objective was to analyse the effect of the structural components of ATS football pitches and running speed on the capacity of impact attenuation. A total of 12 athletes were evaluated at three speed conditions (3.33 m/s, 4 m/s and maximum speed) on four different ATS, classifying them by their components (length of fibre, type of in-fill and sub-base). Impact attenuation was significantly higher in ATS3, characterised by longer fibre compared to other ATS with less fibre length. The ATS4 with a higher length fibre and built on compacted granular material proportioned significantly lower values in the maximum peaks of tibia acceleration. Finally, as speed increases, the peak tibia impacts were significantly higher. Longer fibre length and the capacity to accommodate a higher quantity of infill facilitate higher impact attenuation. Equally, a compacted granular sub-base is related to lower magnitude of maximum tibia peaks. Finally, the magnitude of the tibia acceleration peaks is dependent of running speed for all ATS analysed, being higher as speed increases.


American Football
#1 Brain Network Activation Technology Does Not Assist with Concussion Diagnosis and Return to Play in Football Athletes
Reference: Front Neurol. 2017 Jun 6;8:252. doi: 10.3389/fneur.2017.00252. eCollection 2017.
Authors: Broglio SP, Williams R, Lapointe A, Rettmann A, Moore B, Meehan SK, Eckner JT
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5460056/pdf/fneur-08-00252.pdf
Summary: Concussion diagnosis and management remains a largely subjective process. This investigation sought to evaluate the utility of a novel neuroelectric measure for concussion diagnosis and return to play decision-making. The hypothesis was that Brain Network Activation (BNA) scores obtained within 72-h of injury will be lower than the athlete's preseason evaluation and that of a matched control athlete; and the BNA will demonstrate ongoing declines at the return to play and post-season time points, while standard measures will have returned to pre-injury and control athlete levels. Football athletes with a diagnosed concussion (n = 8) and matched control football athletes (n  = 8) completed a preseason evaluation of cognitive (i.e., Cogstate Computerized Cognitive Assessment Tool) and neuroelectric function (i.e., BNA), clinical reaction time, SCAT3 self-reported symptoms, and quality of life (i.e., Health Behavior Inventory and Satisfaction with Life Scale). Following a diagnosed concussion, injured and control athletes completed post-injury evaluations within 72-h, once asymptomatic, and at the conclusion of the football season. Case analysis of the neuroelectric assessment failed to provide improved diagnostics beyond traditional clinical measures. Statistical analyses indicated significant BNA improvements in the concussed and control groups from baseline to the asymptomatic timepoint. With additional attention being placed on rapid and accurate concussion diagnostics and return to play decision-making, the addition of a novel neuroelectric assessment does not appear to provide additional clinical benefit at this time. Clinicians should continue to follow the recommendations for the clinical management of concussion with the assessment of the symptom, cognitive, and motor control domains.


#2 Cardiovascular disease risk profile of NCAA division III intercollegiate football athletes: a pilot study
Reference: Phys Sportsmed. 2017 Jun 20. doi: 10.1080/00913847.2017.1345288. [Epub ahead of print]
Authors: Wright CJ, Abbey EL, Brandon BA, Reisman EJ, Kirkpatrick CM
Summary: Concerns about the long-term cardiovascular health implications of American football participation have been investigated at the professional and Division I levels, but limited research is available at the less resourced Division III level. Therefore, the objective was to assess the cardiovascular disease risk profile of NCAA Division III intercollegiate football athletes. Eighty-nine varsity football athletes (age=19.6±1.7 years, height=1.81±0.07m, weight=92.7±16.2kg; n=21 linemen, n=68 non-linemen) at a private Division III university volunteered to participate. During a preseason pre-participation physical examination, all participants completed a health history screening form (to assess personal and family history of cardiac related pathologies), and were assessed for height, weight, body mass index (BMI), and blood pressure (BP). Linemen only additionally gave a blood sample for fasting blood glucose and cholesterol analysis, and were assessed for waist and hip circumference, metabolic syndrome, and percent body fat (%BF). These measures were reported as averages and frequencies of elevated cardiovascular. Independent t-tests compared linemen to non-linemen, all other data was presented descriptively. On average, linemen were significantly taller, heavier, had a higher BMI and higher systolic BP than non-linemen (all P<0.05); there was no difference in diastolic BP between the groups (P=0.331). The average anthropometric and cardiac risk characteristics for linemen were largely within normal ranges, however analyzed individually, a substantial number of participants were at elevated risk (BMI ≥30=85.7%, %BF ≥25=71.4%, waist circumference ≥1=42.9%, hypertension=9.5%, high density lipoproteins <40mg/dL=42.9%, and triglycerides ≥150mg/dL=6.7%; metabolic syndrome prevalence=19%). Similar to research in elite athletics, linemen at a single Division III university have elevated cardiovascular disease risk. Physicians and other healthcare providers should consider this elevated risk during pre-participation physical examinations and in planning educational or dietary programming targeted to promoting cardiovascular health.


#3 Effects of turf and cleat footwear on plantar load distributions in adolescent American football players during resisted pushing
Reference: Sports Biomech. 2017 Feb 28:1-11. doi: 10.1080/14763141.2016.1271448. [Epub ahead of print]
Authors: Taylor JB, Nguyen AD, Griffin JR, Ford KR
Summary: Metatarsal and midfoot injuries are common in American football. Footwear design may influence injury rates by altering plantar foot loading patterns in these regions. The purpose of this study was to determine the effect of cleat design on in-shoe plantar foot loading during a football-specific, resisted pushing task. Twenty competitive football players (age 14.7 ± 1.8 years, height 1.72 ± 0.10 m, and mass 71.8 ± 26.9 kg) completed three trials of pushing a weighted sled at maximal effort in a standard shoe (CLEAT) and artificial turf-specific shoe (TURF), with flexible in-shoe force measuring insoles. Repeated measures ANOVAs identified mean differences in maximum force and relative load under all regions of the foot. Results showed higher forces in the CLEAT under the medial (p < 0.001) and lateral (p = 0.004) midfoot, central (p = 0.007) and lateral (p < 0.001) forefoot, and lesser toes (p = 0.01), but lower forces in the hallux (p = 0.02) compared to the TURF shoe. Additionally, relative loading was higher in the CLEAT under the medial (p < 0.001) and lateral (p = 0.002) midfoot and lateral (p < 0.001) forefoot, but lower in the medial forefoot (p = 0.006) and hallux (p < 0.001) compared to the TURF shoe. The two shoes elicited distinct plantar loading profiles and may influence shoe selection decisions during injury prevention or rehabilitation practices.


Australian Football
#1 Preseason Workload Volume and High-Risk Periods for Noncontact Injury Across Multiple Australian Football League Seasons
Reference: J Strength Cond Res. 2017 Jul;31(7):1821-1829. doi: 10.1519/JSC.0000000000001669.
Authors: Colby MJ, Dawson B, Heasman J, Rogalski B, Rosenberg M, Lester L, Peeling P.
Summary: The purpose of this study was to assess the association between preseason workloads and noncontact injury risk in Australian football players. Individual player injury data were recorded over 4 full seasons (2012-15) from one professional club. Noncontact injury incidence (per 1,000 "on legs" field training and game hours) was compared across the preseason, precompetition, and in-season phases to determine relative noncontact injury risk. Preseason workloads (global positioning system-derived total distance run and sprint distance) and individual (fixed) injury risk factors (age, previous injury history) were incorporated into the analysis. A generalized estimating equation with a binary logistic function modeled potential risk factors with noncontact injury for selected periods across the annual cycle. Odds ratios were calculated to determine the relative injury risk. The (preseason) precompetition phase (19.1 injuries per 1,000 hours) and (in-season) rounds 12-17 (16.0 injuries per 1,000 hours) resulted in the highest injury incidence. Low cumulative total distances in late preseason (<108 km) and precompetition (76-88 km) periods were associated with significantly (p ≤ 0.05) greater injury risk during the in-season phase. In conclusion, these results suggest players are at the greatest injury risk during the precompetition period, with low preseason cumulative workloads associated with increased in-season injury risk. Therefore, strength and conditioning staff should place particular emphasis on achieving at least moderate training loads during and leading into this phase, where competitive game play is first introduced.


#2 Interchange rotation factors and player characteristics influence physical and technical performance in professional Australian Rules football
Reference: J Sci Med Sport. 2017 Jun 8. pii: S1440-2440(17)30455-3. doi: 10.1016/j.jsams.2017.06.008. [Epub ahead of print]
Authors: Dillon PA, Kempton T, Ryan S, Hocking J, Coutts AJ
Summary: The purpose was to examine the effects of match-related and individual player characteristics on activity profile and technical performance during rotations in professional Australian football. Global positioning system data and player rating scores were collected from 33 professional Australian football players during 15 Australian football League matches. Player rating scores were time aligned with their relative total and high-speed running (HSR) distance (>20kmh-1) for each on ground rotation. Individual players' maximal aerobic running speed (MAS) was determined from a two-kilometre trial. A multilevel linear mixed model was used to examine the influence of rotations on physical activity profiles and skill execution during match play. Rotation duration and accumulated distance resulted in a trivial-to-moderate reduction in relative total and HSR distances as well as relative rating points. The number of disposals in a rotation had a small positive effect on relative total and HSR distances and a large positive effect on relative rating points. MAS was associated with a moderate-to-large increase in relative total distance, but had a large negative effect on relative rating points. Previous rotation time, stoppages and the number of rotations in the quarter had a trivial-to-small negative effect on relative total and HSR distances. A greater speed (mmin-1) was associated with a trivial increase in rating points during a rotation, while there was a trivial decrease in relative total distance as rating points increased. The complex relationship between factors that influence activity profile and technical performance during rotations in Australian football needs to be considered when interpreting match performance.


Gaelic Football
#1 Physiological Profile and Activity Pattern of Minor Gaelic Football Players
Reference: J Strength Cond Res. 2017 Jul;31(7):1811-1820. doi: 10.1519/JSC.0000000000001667.
Authors: Cullen BD, Roantree MT, McCarren AL, Kelly DT, OʼConnor PL, Hughes SM, Daly PG, Moyna NM.
Summary: The purpose of this study was to evaluate the physiological profile and activity pattern in club- and county-level under-18 (U-18) Gaelic football players relative to playing position. Participants (n = 85) were analyzed during 17 official 15-a-side matches using global positioning system technology (SPI Pro X II; GPSports Systems, Canberra, Australia) and heart rate (HR) telemetry. During the second part of this study, 63 participants underwent an incremental treadmill test to assess their maximal oxygen uptake (V[Combining Dot Above]o2max) and peak HR (HRmax). Players covered a mean distance of 5,774 ± 737 m during a full 60-minute match. The mean %HRmax and %V[Combining Dot Above]O2max observed during the match play were 81.6 ± 4.3% and 70.1 ± 7.75%, respectively. The playing level had no effect on the distance covered, player movement patterns, or %HRmax observed during match play. Midfield players covered significantly greater distance than defenders (p = 0.033). Playing position had no effect on %HRmax or the frequency of sprinting or high-intensity running during match play. The frequency of jogging, cruise running, striding (p = 0.000), and walking (p = 0.003) was greater in the midfield position than in the forward position. Time had a significant effect (F(1,39) = 33.512, p-value = 0.000, and (Equation is included in full-text article.)= 0.462) on distance covered and %HRmax, both of which showed a reduction between playing periods. Gaelic football is predominantly characterized by low-to-moderate intensity activity interspersed with periods of high-intensity running. The information provided may be used as a framework for coaches in the design and prescription of training strategies. Positional specific training may be warranted given the comparatively greater demands observed in the midfield playing position. Replicating the demands of match play in training may reduce the decline in distance covered and %HRmax observed during the second half of match play.


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