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1.  Exercise‐induced homeostatic perturbations provoked by singles tennis match play with reference to development of fatigue 
British Journal of Sports Medicine  2007;41(11):717-722.
This review addresses metabolic, neural, mechanical and thermal alterations during tennis match play with special focus on associations with fatigue. Several studies have provided a link between fatigue and the impairment of tennis skills proficiency. A tennis player's ability to maintain skilled on‐court performance and/or optimal muscle function during a demanding match can be compromised as a result of several homeostatic perturbations, for example hypoglycaemia, muscle damage and hyperthermia. Accordingly, an important physiological requirement to succeed at competitive level might be the player's ability to resist fatigue. However, research evidence on this topic is limited and it is unclear to what extent players experience fatigue during high‐level tennis match play and what the physiological mechanisms are that are likely to contribute to the deterioration in performance.
doi:10.1136/bjsm.2007.037259
PMCID: PMC2465283  PMID: 17957005
2.  The effect of sports specific training on reducing the incidence of hamstring injuries in professional Australian Rules football players 
Objectives: To assess in a single team of Australian Rules football players the effect of a specific intervention program on the incidence and consequence of hamstring muscle strain injuries.
Method: A prospective study was performed with a single team being followed for four playing seasons for hamstring injury. Magnetic resonance imaging was used to confirm the diagnosis of hamstring muscle injury. After two playing seasons an intervention program was implemented with the number of athletes with hamstring injury, competition days missed, and incidence of hamstring match injuries per 1000 h of playing time being compared pre- and post-intervention. The intervention program involved stretching whilst fatigued, sport specific training drills, and an emphasis on increasing the amount of high intensity anaerobic interval training.
Results: In the seasons prior to the intervention, nine and 11 athletes sustained hamstring injury compared to two and four following intervention. Competition days missed reduced from 31 and 38 to 5 and 16 following intervention and match incidence decreased from 4.7 to 1.3 per 1000 h of playing time. A beneficial effect was demonstrated with a smaller number of players having hamstring injuries (p = 0.05), a lower number of competition games missed being recorded (p<0.001), and a decrease in hamstring strain incidence per 1000 h of playing time (p = 0.01) following the intervention program.
Conclusions: Increasing the amount of anaerobic interval training, stretching whilst the muscle is fatigued, and implementing sport specific training drills resulted in a significant reduction in the number and consequences of hamstring muscle strain injuries.
doi:10.1136/bjsm.2005.018697
PMCID: PMC1725238  PMID: 15911608
3.  Maximal anaerobic power in national level Indian players. 
The comparative study of aerobic power in different sports was conducted on 99 National Senior as well as National Junior players specialised in hockey and football, field games; volleyball and basketball, court games. The National Seniors were 27 hockey and 16 volleyball players, whereas, 32 football and 24 basketball players were the National Juniors. The maximal anaerobic power of the players was determined from maximal vertical velocity and body weight by the methods of margaria. The football players have been found to be highest followed by hockey, volleyball and basketball players in vertical velocity. It is observed that field game players are higher than the court game players in vertical velocity and that volleyball players possess higher maximum anaerobic power than football, hockey and basketball players.
Images
PMCID: PMC1858887  PMID: 7317726
4.  The Physiological Demands of Table Tennis: A Review 
Although table tennis has a tradition lasting more than 100 years, relatively little is known about players’ physiological requirements – especially during competition. In this review we discuss research studies that have led to our current understanding of how the body functions during table tennis training and competition and how this is altered by training. Match and practice analysis of the table tennis game indicates that during intense practice and competition it is predominantly the anaerobic alactic system that is called into play, while the endurance system is relied on to recovery the anaerobic stores used during such effort. It is thus important for coaches to keep in mind that, while the anaerobic alactic system is the most energetic system used during periods of exertion in a table tennis game, a strong capacity for endurance is what helps a player recover quicker for the following match and the next day of competition. This paper provides a review of specific studies that relate to competitive table tennis, and highlights the need for training and research programs tailored to table tennis.
Key PointsMatch and practice analysis of the table tennis game indicates that during intense practice and competition it is predominantly the anaerobic alactic system that is called into play.The endurance system is relied on to recovery the anaerobic stores used during hard practice and competition effort.It is important for coaches to keep in mind that, while the anaerobic alactic system is the most energetic system used during periods of exertion in a table tennis game, a strong capacity for endurance is what helps a player recover quicker for the following match and the next day of competition.
PMCID: PMC3772576  PMID: 24149139
Racket sports; measurement; physiology; loads
5.  Injury surveillance in the World Football Tournaments 1998–2012 
British Journal of Sports Medicine  2012;47(12):782-788.
Background
International sports bodies should protect the health of their athletes, and injury surveillance is an important pre-requisite for injury prevention. The Fédération International de Football Association (FIFA) has systematically surveyed all football injuries in their tournaments since 1998.
Aims
Analysis of the incidence, characteristics and changes of football injury during international top-level tournaments 1998–2012.
Methods
All newly incurred football injuries during the FIFA tournaments and the Olympic Games were reported by the team physicians on a standardised injury report form after each match. The average response rate was 92%.
Results
A total of 3944 injuries were reported from 1546 matches, equivalent to 2.6 injuries per match. The majority of injuries (80%) was caused by contact with another player, compared with 47% of contact injuries by foul play. The most frequently injured body parts were the ankle (19%), lower leg (16%) and head/neck (15%). Contusions (55%) were the most common type of injury, followed by sprains (17%) and strains (10%). On average, 1.1 injuries per match were expected to result in absence from a match or training. The incidence of time-loss injuries was highest in the FIFA World Cups and lowest in the FIFA U17 Women's World Cups. The injury rates in the various types of FIFA World Cups had different trends over the past 14 years.
Conclusions
Changes in the incidence of injuries in top-level tournaments might be influenced by the playing style, refereeing, extent and intensity of match play. Strict application of the Laws of the Games is an important means of injury prevention.
doi:10.1136/bjsports-2013-092205
PMCID: PMC3717759  PMID: 23632746
Soccer; Epidemiology; Sporting injuries; Injury Prevention
6.  BEHAVIORAL COACHING TO IMPROVE OFFENSIVE LINE PASS-BLOCKING SKILLS OF HIGH SCHOOL FOOTBALL ATHLETES 
We evaluated several behavioral coaching procedures for improving offensive line pass-blocking skills with 5 high school varsity football players. Pass blocking was measured during practice drills and games, and our intervention included descriptive feedback with and without video feedback and teaching with acoustical guidance (TAG). Intervention components and pass blocking were evaluated in a multiple baseline design, which showed that video feedback and TAG were the most effective procedures. For all players, improved pass blocking matched a standard derived by observing more experienced linemen and was evident in games. Additional intervention was required to maintain pass-blocking proficiency. Issues pertinent to behavioral coaching and sport psychology research are discussed.
doi:10.1901/jaba.2010.43-463
PMCID: PMC2938948  PMID: 21358905
behavioral coaching; football; performance feedback; teaching with acoustical guidance
7.  Short Communication on the Influence of Position on Anterior Cruciate Ligament Injury and Reconstruction in Recreational Rugby Football Union Participants 
The different player positions in rugby union may place varying demands on a reconstructed anterior cruciate ligament (ACL) in regards to ‘cutting manoeuvres’, this in turn may effect performance. In order to investigate sporting performance post reconstruction, a questionnaire was sent to amateur rugby clubs affiliated to the Oxfordshire Rugby Football Union (R.F.U). From the returned questionnaires player positions were placed into categories based on similar ‘cutting manoeuvre’ demands. Seventy five percent of Individuals playing in the category 1 (low ‘cutting manoeuvre’ demands at slow running speeds) could play a full game with a damaged ACL and post-reconstruction the majority returned to play at a higher level. Fifty percent of ACL injuries occurred on category 2 (high ‘cutting manoeuvre’ demands at medium running speeds) suggesting they may be more prone to ACL injury than other positions. The majority of individuals playing in category 3 (high ‘cutting manoeuvre’ demands at fast speeds) played at a lower level of rugby post reconstruction. Positional demands may influence ACL injury and post reconstruction sporting performance. However, more research is needed.
PMCID: PMC3937572  PMID: 24616607
Anterior cruciate ligament reconstruction; rugby football; player position
8.  American football injuries in Finland. 
American football is currently played in 14 European countries. It is a contact sport where injuries are inevitable. In this study, injuries causing more than one week of absence from game or practise were registered during the 1991 preseason and season. A total of 112 injuries was reported among 684 players. Knees were most vulnerable to injury (28.6%) followed by ankle injuries (16.7%). Operations were performed on 28 (25%) of the injured players. Catastrophic injuries can occur in this sport, but none has happened in Finland during the 12 years for which the sport has been practised. The skill level was not a contributing factor. The frequency of injuries and their profile closely resemble those in US-based studies so it is suggested that the precautions and preventive measures recommended in the USA should be applied and followed in Europe.
PMCID: PMC1332137  PMID: 8358586
9.  The effects of exertion on the postural stability in young soccer players 
Acta Ortopedica Brasileira  2013;21(3):155-158.
OBJECTIVE
: Analyze the effects of physical exertion during a soccer match on the functional capacity and stability of the lower limbs of young soccer players.
METHODS
: We analyzed 10 soccer players who underwent functional capacity assessment of the lower limbs by a Hop Test protocol and evaluation of the level of postural stability in the Biodex Stability System (Biodex, Inc., Shirley, NY) before and immediately after a friendly game lasting 45 minutes.
RESULTS
: After the match, there was a decrease in overall stability index (F(1,23) = 7.29 P = .024) and anterior posterior index (APSI) (F(1,23) = 5.53 P = .043). Fatigue in the dominant limb was responsible for the significant deficit in OSI (F(1,23) = 3.16, P = .047) and APSI (F(1,23) = 3:49, P = .029), while the non-dominant limb did not cause any change in the pre and post-game.
CONCLUSION
: A football match can cause decreased stability and functional capacity of the lower limbs in young players. Level of Evidence III, Pre-test and Post-test Study (Case-control).
doi:10.1590/S1413-78522013000300005
PMCID: PMC3862001  PMID: 24453660
Soccer; Fatigue; Athletic injuries; Posture
10.  Physiological Responses and Physical Performance during Football in the Heat 
PLoS ONE  2012;7(6):e39202.
Purpose
To examine the impact of hot ambient conditions on physical performance and physiological responses during football match-play.
Methods
Two experimental games were completed in temperate (∼21°C; CON) and hot ambient conditions (∼43°C; HOT). Physical performance was assessed by match analysis in 17 male elite players during the games and a repeated sprint test was conducted after the two game trials. Core and muscle temperature were measured and blood samples were obtained, before and after the games.
Results
Muscle and core temperatures were ∼1°C higher (P<0.05) in HOT (40.3±0.1 and 39.5±0.1°C, respectively) compared to CON (39.2±0.1 and 38.3±0.1°C). Average heart rate, plasma lactate concentration, body weight loss as well as post-game sprint performance were similar between the two conditions. Total game distance declined (P<0.05) by 7% and high intensity running (>14 km⋅h−1) by 26% in HOT compared to CON), but peak sprint speed was 4% higher (P<0.05) in HOT than in CON, while there were no differences in the quantity or length of sprints (>24 km⋅h−1) between CON and HOT. In HOT, success rates for passes and crosses were 8 and 9% higher (P<0.05), respectively, compared to CON. Delta increase in core temperature and absolute core temperature in HOT were correlated to total game distance in the heat (r = 0.85 and r = 0.53, respectively; P<0.05), whereas, total and high intensity distance deficit between CON and HOT were not correlated to absolute or delta changes in muscle or core temperature.
Conclusion
Total game distance and especially high intensity running were lower during a football game in the heat, but these changes were not directly related to the absolute or relative changes in core or muscle temperature. However, peak sprinting speed and execution of successful passes and crosses were improved in the HOT condition.
doi:10.1371/journal.pone.0039202
PMCID: PMC3378691  PMID: 22723963
11.  Spectrum of acute clinical characteristics of diagnosed concussions in college athletes wearing instrumented helmets 
Journal of neurosurgery  2012;117(6):1092-1099.
Object
Concussive head injuries have received much attention in the medical and public arenas, as concerns have been raised about the potential short- and long-term consequences of injuries sustained in sports and other activities. While many student athletes have required evaluation after concussion, the exact definition of concussion has varied among disciplines and over time. The authors used data gathered as part of a multiinstitutional longitudinal study of the biomechanics of head impacts in helmeted collegiate athletes to characterize what signs, symptoms, and clinical histories were used to designate players as having sustained concussions.
Methods
Players on 3 college football teams and 4 ice hockey teams (male and female) wore helmets instrumented with Head Impact Telemetry (HIT) technology during practices and games over 2–4 seasons of play. Preseason clinical screening batteries assessed baseline cognition and reported symptoms. If a concussion was diagnosed by the team medical staff, basic descriptive information was collected at presentation, and concussed players were reevaluated serially. The specific symptoms or findings associated with the diagnosis of acute concussion, relation to specific impact events, timing of symptom onset and diagnosis, and recorded biomechanical parameters were analyzed.
Results
Data were collected from 450 athletes with 486,594 recorded head impacts. Forty-eight separate concussions were diagnosed in 44 individual players. Mental clouding, headache, and dizziness were the most common presenting symptoms. Thirty-one diagnosed cases were associated with an identified impact event; in 17 cases no specific impact event was identified. Onset of symptoms was immediate in 24 players, delayed in 11, and unspecified in 13. In 8 cases the diagnosis was made immediately after a head impact, but in most cases the diagnosis was delayed (median 17 hours). One diagnosed concussion involved a 30-second loss of consciousness; all other players retained alertness. Most diagnoses were based on self-reported symptoms. The mean peak angular and rotational acceleration values for those cases associated with a specific identified impact were 86.1 ± 42.6g (range 16.5–177.9g) and 3620 ± 2166 rad/sec2 (range 183–7589 rad/sec2), respectively.
Conclusions
Approximately two-thirds of diagnosed concussions were associated with a specific contact event. Half of all players diagnosed with concussions had delayed or unclear timing of onset of symptoms. Most had no externally observed findings. Diagnosis was usually based on a range of self-reported symptoms after a variable delay. Accelerations clustered in the higher percentiles for all impact events, but encompassed a wide range. These data highlight the heterogeneity of criteria for concussion diagnosis, and in this sports context, its heavy reliance on self-reported symptoms. More specific and standardized definitions of clinical and objective correlates of a “concussion spectrum” may be needed in future research efforts, as well as in the clinical diagnostic arena.
doi:10.3171/2012.8.JNS112298
PMCID: PMC3716254  PMID: 23030057
concussion; traumatic brain injury; biomechanics; athletes; football; hockey
12.  A National Survey About Parent Awareness of the Risk of Severe Brain Injury From Playing Football 
Journal of Athletic Training  1993;28(4):306-311.
A survey was conducted to determine the level of awareness among parents of high school football players about the risk of severe brain injury. A national sample of 1007 randomly selected households was interviewed by telephone during February, 1992. All interviewees were parents of high school football players who either were currently playing football or had played within the previous 5 years. Survey questions measured the extent to which parents were aware both of the risks associated with playing high school football and the existing helmet warnings about those risks. Overall, the survey results demonstrated that parents of high school football players were uninformed about both the risk of severe brain injury from playing high school football and the football helmet warnings about that risk. Specifically, unprompted, most parents mentioned broken bones, knee injuries, sprains, or shoulder injuries as hazards associated with playing football. Few parents mentioned severe brain damage, even when prompted. Further, the overwhelming majority of parents incorrectly believed that wearing a football helmet generally eliminated the risk of severe brain injury. Very few parents had received information from any source about the risks of head injury or had heard that no football helmet can provide complete protection against this hazard. Few parents were aware of the warning label on the helmet or knew what the label said, even when prompted. In short, parents were unaware of the risk of severe brain damage, misinformed about a football helmet's ability to protect against this risk, and uninformed about the football helmet warning label about this risk.
PMCID: PMC1317733  PMID: 16558245
13.  The physiological demands of Gaelic football. 
Match-lay demands of Gaelic football and fitness profiles were assessed at club competitive level. English Gaelic football club championship players (n = 11) were assessed for anthropometry, leg strength and time to exhaustion on a treadmill run. A similar test battery was administered to a reference group of University competitive soccer players (n = 12). Heart rate was recorded during match-play using radio telemetry and blood lactate concentrations were determined at half-time and after full-time. No differences (p > 0.05) were observed between the Gaelic and soccer players in: body mass (70.7 +/- 10.3 vs 76.6 +/- 10.3 kg); height (176 +/- 5.9 vs 177.7 +/- 6.4 cm); leg to trunk ratio (0.53 +/- 0.01 vs 0.54 +/- 0.03); adiposity (12.2 +/- 2.1 vs 13.5 +/- 3.2% body fat); mean somatotype (2.8 - 4.3-2.0 vs 2.4-4.2-2.4); leg strength measures; and performance on the treadmill. The percentage muscle mass values were lower for the Gaelic players compared to the soccer players (41.9 +/- 5.4 vs 47.3 +/- 5.2%; p > 0.005). For the Gaelic and soccer players, respectively, mean heart rate recorded during each half of match-play were (157 +/- 10 and 158 +/- 12 beats/min) and (164 +/- 10 and 157 +/- 11 beats/min), whilst blood lactates measured at the end of each half, were (4.3 +/- 1 and 3.4 +/- 1.6 mmol/l) and (4.4 +/- 1.2 and 4.5 +/- 2.1 mmol/l). Gaelic footballers at English club championship level seem to exhibit similar fitness profiles, and are subject to broadly similar physiological demands as University-level competitive soccer players.
Images
PMCID: PMC1332217  PMID: 7788217
14.  Specific incremental field test for aerobic fitness in tennis 
Objectives
To compare metabolic and cardiorespiratory responses between subjects undergoing incremental treadmill (non‐specific) and tennis field based (sport specific) tests.
Methods
Nine junior competitive tennis players randomly performed two incremental protocols to exhaustion: a treadmill test (TT) and a tennis specific fitness test (FT). The FT consisted of repeated displacements replicating the game of tennis at increasing speed on a court. In both tests, ventilatory variables and heart rate (HR) were determined at the ventilatory threshold (VT), respiratory compensation point (RCP), and maximal loads (max). Blood lactate concentration was determined at the point of volitional fatigue.
Results
Percentage (mean (SD)) maximal HR (83.6 (5.1) v 83.0 (2.8) and 92.1 (2.1) v 92.3 (2.1)%, respectively) and percentage maximal oxygen uptake (VO2max) (69.4 (8.1) v 73.5 (6.1) and 84.4 (6.5) v 85.5 (8.7)%, respectively) at the VT and RCP were not different between the FT and TT subjects, whereas VO2max was higher in the FT than in the TT (63.8 (3.0) v 58.9 (5.3) ml/min/kg; p<0.05). Blood lactate concentration (10.7 (3.0) v 10.6 (4.3) mmol/l) did not differ between the TT and FT.
Conclusions
Although cardiorespiratory variables were not different at submaximal intensities between the two tests, VO2max values derived from laboratory measurements were underestimated. Using field testing in addition to treadmill testing provides a better measurement of a player's individual fitness level and may be routinely used to accurately prescribe appropriate aerobic exercise training.
doi:10.1136/bjsm.2006.027680
PMCID: PMC2564396  PMID: 16855066
field testing; performance; physiological responses; racquet sport; training
15.  Effect of incorporating low intensity exercise into the recovery period after a rugby match 
Background: The psychological and physiological condition of athletes affect both their performance in competitions and their health. Rugby is an intense sport which appears to impose psychological and physiological stress on players. However, there have been few studies of the most appropriate resting techniques to deliver effective recovery from a match.
Objectives: To compare the difference in recovery after a match using resting techniques with or without exercise.
Methods: Fifteen Japanese college rugby football players were studied. Seven performed only normal daily activities and eight performed additional low intensity exercise during the post-match rest period. Players were examined just before and immediately after the match and one and two days after the match. Blood biochemistry and two neutrophil functions, phagocytic activity and oxidative burst, were measured to assess physiological condition, and the profile of mood states (POMS) scores were examined to evaluate psychological condition.
Results: Immediately after the match, muscle damage, decreases in neutrophil functions, and mental fatigue were observed in both groups. Muscle damage and neutrophil functions recovered with time almost equally in the two groups, but the POMS scores were significantly decreased only in subjects in the low intensity exercise group.
Conclusions: Rugby matches impose both physiological and psychological stress on players. The addition of low intensity exercise to the rest period did not adversely affect physiological recovery and had a significantly beneficial effect on psychological recovery by enhancing relaxation.
doi:10.1136/bjsm.2002.004309
PMCID: PMC1724892  PMID: 15273179
16.  Frequency and Location of Head Impact Exposures in Individual Collegiate Football Players 
Journal of Athletic Training  2010;45(6):549-559.
Abstract
Context:
Measuring head impact exposure is a critical step toward understanding the mechanism and prevention of sport-related mild traumatic brain (concussion) injury, as well as the possible effects of repeated subconcussive impacts.
Objective:
To quantify the frequency and location of head impacts that individual players received in 1 season among 3 collegiate teams, between practice and game sessions, and among player positions.
Design:
Cohort study.
Setting:
Collegiate football field.
Patients or Other Participants:
One hundred eighty-eight players from 3 National Collegiate Athletic Association football teams.
Intervention(s):
Participants wore football helmets instrumented with an accelerometer-based system during the 2007 fall season.
Main Outcome Measure(s):
The number of head impacts greater than 10g and location of the impacts on the player's helmet were recorded and analyzed for trends and interactions among teams (A, B, or C), session types, and player positions using Kaplan-Meier survival curves.
Results:
The total number of impacts players received was nonnormally distributed and varied by team, session type, and player position. The maximum number of head impacts for a single player on each team was 1022 (team A), 1412 (team B), and 1444 (team C). The median number of head impacts on each team was 4.8 (team A), 7.5 (team B), and 6.6 (team C) impacts per practice and 12.1 (team A), 14.6 (team B), and 16.3 (team C) impacts per game. Linemen and linebackers had the largest number of impacts per practice and per game. Offensive linemen had a higher percentage of impacts to the front than to the back of the helmet, whereas quarterbacks had a higher percentage to the back than to the front of the helmet.
Conclusions:
The frequency of head impacts and the location on the helmet where the impacts occur are functions of player position and session type. These data provide a basis for quantifying specific head impact exposure for studies related to understanding the biomechanics and clinical aspects of concussion injury, as well as the possible effects of repeated subconcussive impacts in football.
doi:10.4085/1062-6050-45.6.549
PMCID: PMC2978006  PMID: 21062178
biomechanics; concussions; accelerometers
17.  Epidemiology of injuries in typical Scandinavian team sports. 
An investigation by questionnaire was undertaken in a group of 480 football players and 288 handball players (768 players). Of these 803 were injured, giving a player incidence of 4.1 injury/1000 football hours and 8.3 injury/1000 handball hours. The lower extremities were involved in 82% of the football injuries, whereas handball injuries were evenly distributed on both upper and lower extremities. The football injury prevalence was 0.36 per player, the handball injury prevalence 0.71 per player. Medical attention was given to 62% of the injured footballers and 47% of the injured handballers. Based on the injury pattern, some modifications to the rules and equipment in the two sports is suggested: The "boot-type" footwear should be tried out, and the soles in both games should correspond to the different playing surfaces that may be encountered. Stricter enforcement of the rules, and the use of a maximum size playing ground in both sports. Last, but not least a modification of the football rules concerning substitution is a must.
Images
PMCID: PMC1859202  PMID: 6466931
18.  Direct Versus Indirect Supervision of Fellows Covering Football Events: A Survey of Fellows and Program Directors 
Background
The Accreditation Council for Graduate Medical Education (ACGME) program requirements mandate “adequate supervision,” of residents, but there is little guidance for sports medicine fellowship directors regarding the transition from direct to indirect supervision of fellows covering football games.
Objective
We sought to gather evidence of current supervision practices in the context of injury outcomes.
Methods
Fellows and program directors of ACGME-accredited sports medicine fellowship programs were invited to complete an online survey regarding their experience and current supervision practice at football games. Criteria for transition to autonomy and desired changes in supervision practice were elicited. Player safety was quantified by noting the number of field-side emergencies, whether an attending was present, and whether better outcomes might have resulted from the presence of an attending.
Results
A total of 80 fellows and 50 program directors completed the online survey. Direct supervision was lacking in about 50% of high school games and 20% of college games. A resulting cost in terms of player safety was estimated to apply to 5% of serious injuries by fellows' report but less than 0.5% by directors' report. Written criteria for transitioning from direct supervision to autonomy were the exception rather than the rule. The majority of fellows and directors expressed satisfaction with the current level of supervision, but 20% of fellows would prefer more supervision through postgame review.
Conclusions
Football games covered by fellows are often not directly supervised. Absence of an attending affected the outcomes of 5% or less of serious injuries. Transition to autonomy does not usually require meeting written criteria. Fellows might benefit from additional off-site supervision.
doi:10.4300/JGME-D-10-00038.1
PMCID: PMC2951787  PMID: 21976096
19.  Cytokines and Oxidative Stress Status Following a Handball Game in Elite Male Players 
Background. Handball is considered an intermittent sport that places an important stress on a player's aerobic and anaerobic metabolism. However, the oxidative stress responses following a handball game remain unknown. We investigated the responses of plasma and erythrocyte antioxidant system and oxidative stress biomarkers following a single handball game. Methods. Fourteen male elite Brazilian handball athletes were recruited in the present study. Blood samples were taken before, immediately, and 24 hours after the game. Results. After the game and during 24 hours of recovery, the concentration of all oxidative stress indices changed significantly in a way indicating increased oxidative stress in the blood (thiol groups and reduced glutathione decreased, whereas TBARS and plasma antioxidant capacity was increased) as well as in erythrocyte (increased levels of TBARS and protein carbonyls). Erythrocyte antioxidant enzyme activities were also significantly changed by handball. Muscle damage indices (creatine kinase and lactate dehydrogenase) increased significantly after exercise. In addition, IL-6 increased after the game, whereas TNF-α decreased during recovery. Conclusion. This study demonstrates that a single handball game in elite athletes induces a marked state of oxidative stress evidenced by the oxidative modification in plasma and erythrocyte macromolecules, as well as by changes in the enzymatic and nonenzymatic antioxidant system.
doi:10.1155/2011/804873
PMCID: PMC3172986  PMID: 21922038
20.  A congested football calendar and the wellbeing of players: correlation between match exposure of European footballers before the World Cup 2002 and their injuries and performances during that World Cup 
Objectives: To investigate the correlation between exposure of footballers in European clubs to match play in the months before the World Cup 2002 and their injuries and performances during that World Cup.
Methods: The team doctors at 11 of the best football clubs in Europe prospectively recorded players' exposure and injuries during the 2001–2002 season (July 2001–May 2002). Sixty five players participated in the World Cup in Korea/Japan (June 2002). During the World Cup, the clubs reported injuries sustained by these players, and their performance was evaluated by three international experts.
Results: The number of team matches during the season varied between 40 and 76 for the different countries involved. The individual player had a mean of 36 matches during the season. Top players played more matches, especially during the final period of the season. Players who participated in the World Cup played more matches during the season than those who did not (46 v 33 matches). World Cup players did not show any increased risk of injury during the season. About 29% incurred injuries during the World Cup, and 32% performed below their normal standard. The players who underperformed had played more matches during the 10 weeks before the World Cup than those who performed better than expected (12.5 v 9, p<0.05). Twenty three (60%) of the 38 players who had played more than one match a week before the World Cup incurred injuries or underperformed during the World Cup.
Conclusions: There is considerable variation in the number of matches played per season in European professional football leagues. Top level players are obliged to play many matches especially during the final period of the season.
doi:10.1136/bjsm.2003.009134
PMCID: PMC1724854  PMID: 15273193
21.  Squash ball to eye ball: the likelihood of squash players incurring an eye injury. 
The records of the 118 patients treated as Southampton Eye Hospital during 1978-9 for injuries incurred while playing squash, badminton, tennis, table tennis, cricket, and football show that for squash the main cause of eye injury was the player being hit by the ball. Severe eye injuries--those requiring treatment as an inpatient--were rare but much more frequent than such injuries in other sports. Less serious injuries--those requiring treatment as an outpatient--were also rare, with a frequency comparable with that of similar injuries in football and badminton. Squash players are most unlikely to incur an eye injury, but should this occur it has far-reaching consequences both in the short and the long term. Each individual player must weigh these chances and consequences against the possible inconvenience of using some form of eye protection.
PMCID: PMC1507155  PMID: 6793167
22.  Stress fracture risk factors in female football players and their clinical implications 
British Journal of Sports Medicine  2007;41(Suppl 1):i38-i43.
A stress fracture represents the inability of the skeleton to withstand repetitive bouts of mechanical loading, which results in structural fatigue, and resultant signs and symptoms of localised pain and tenderness. Reports of stress fractures in female football players are not prevalent; however, they are probably under‐reported and their importance lies in the morbidity that they cause in terms of time lost from participation. By considering risk factors for stress fractures in female football players it may be possible to reduce the impact of these troublesome injuries. Risk factors for stress fractures in female football players include intrinsic risk factors such as gender, endocrine, nutritional, physical fitness and neuromusculoskeletal factors, as well as extrinsic risk factors such as training programme, equipment and environmental factors. This paper discusses these risk factors and their implications in terms of developing prevention and management strategies for stress fractures in female football players.
doi:10.1136/bjsm.2007.037804
PMCID: PMC2465247  PMID: 17584950
23.  Effects of posting self-set goals on collegiate football players' skill execution during practice and games. 
The effects of self-set goals and public posting on athletic performance of 5 collegiate football players was studied. All players were linebackers on a National Association of Intercollegiate Athletics Division II football team. The dependent variables were the percentage of correct occasions when the linebacker (a) positioned himself to cover a specified area on the field during a pass or from the line of scrimmage during a run; (b) moved to the correct position in response to the positioning of the offense; and (c) tackled and stopped the progress of the ball carrier. A multiple baseline design across behaviors showed an immediate increase in the practice performance of the players and a corresponding increase in game performance following introduction of the independent variable. This study extends research using public posting in sport by demonstrating the effects of player-determined goals and public posting of goal attainment.
doi:10.1901/jaba.2002.35-1
PMCID: PMC1284356  PMID: 11936542
24.  Update in the understanding of altitude-induced limitations to performance in team-sport athletes 
British Journal of Sports Medicine  2013;47(Suppl 1):i22-i25.
The internationalism of field-based team sports (TS) such as football and rugby requires teams to compete in tournaments held at low to moderate altitude (∼1200–2500 m). In TS, acceleration, speed and aerobic endurance are physical characteristics associated with ball possession and, ultimately, scoring. While these qualities are affected by the development of neuromuscular fatigue at sea level, arterial hypoxaemia induced by exposure to altitude may further hinder the capacity to perform consecutive accelerations (CAC) or sprint endurance and thereby change the outcome of a match. The higher the altitude, the more severe the hypoxaemia, and thus, the larger the expected decline in aerobic endurance, CAC and match running performance. Therefore, it is critical for athletes and coaches to understand how arterial hypoxaemia affects aerobic endurance and CAC and the magnitude of decline they may face at altitude for optimal preparation and increased chances of success. This mini review summarises the effects of acute altitude/hypoxia exposure on aerobic endurance, CAC and activity profiles of TS athletes performing in the laboratory and during matches at natural altitude, and analyses the latest findings about the consequences of arterial hypoxaemia on the relationship between peripheral perturbations, neural adjustments and performance during repeated sprints or CAC. Finally, we briefly discuss how altitude training can potentially help athletes prepare for competition at altitude.
doi:10.1136/bjsports-2013-092834
PMCID: PMC3903141  PMID: 24282202
Altitude; Exercise physiology; Fatigue; Soccer
25.  A behavioral approach to coaching football: improving the play execution of the offensive backfield on a youth football team 
Because of the emphasis on winning, the difficulties involved in assessing performance, and the lack of frequent and contingent reinforcement, a behavioral approach to coaching football was used. The players, all nine- or ten-year-old males, were members of an offensive backfield on a Pop Warner football team. Three frequently-run offensive plays were broken down into a series of five behaviorally defined stages, permitting construction of checklists suitable for observing the players during both game and scrimmage sessions. The intervention consisted of the presentation and explanation of the appropriate checklist, and frequent contingent reinforcement in the form of feedback and recognition for instances of desired play execution. Performance gains averaging 20% occurred for each of the three plays after, and not before, the staggered introduction of each intervention. The results suggest that behavioral specification and positive reinforcement of desired play execution is a viable approach to the coaching of football.
doi:10.1901/jaba.1977.10-657
PMCID: PMC1311243  PMID: 16795571
physical education; sports; football; coaching; behavioral approach; reinforcement; multiple baseline; feedback; youths

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