Contextual considerations using the ′control-chaos continuum′ for return to sport in elite football - Part 1: Load planning

The ‘control-chaos continnum’ is an adaptable framework developed to guide the on-pitch rehabilitation process in elite football. One of the key objectives of the continuum is to progressively return players to their preinjury chronic running load, while incorporating the qualitative aspects of movement and cognitive stresses integral to competitive match-play. Whilst injury and player-specific considerations are key to an individualised rehabilitation approach, a host of contextual factors also play an important role in return to sport (RTS) planning. In this article, we highlight some key intrinsic and extrinsic contextual factors for the practitioner to consider in the RTS planning process to help mitigate reinjury risk upon a return to team training. While a return to chronic running load is generally a critical component of the framework, we highlight circumstances in elite football where it is a less relevant factor in RTS decision-making.     

Rehabilitation of an isolated Deltoid Ligament surgical reconstruction- A case report

ObjectivesIsolated deltoid ligament injuries are an uncommon injury within football with a lack of literature surrounding the rehabilitation processes for this injury. This case report looks to document the processes and considerations required for a successful rehabilitation of this specific injury to promote discussion surrounding optimal rehabilitation programming and subsequently better inform clinicians about best practice.MethodsA twenty-year-old professional footballer sustained an isolated Deltoid ligament injury to their right ankle following an eversion mechanism of injury when landing after performing a heading action. Eleven days post injury the player underwent reconstruction of the Deltoid ligament before then undergoing a sixteen-week rehabilitation program up to the point of return to training.ResultsThis complete deltoid ligament rupture was managed surgically with a reconstruction. Following sixteen weeks of rehabilitation the player was cleared for a return to training and has now been in full training and match play involvement for nine months without any reaction or reinjury.ConclusionThis case report summarises the injury management, rehabilitation and objective markers used in order to provide some early understanding of management strategies for this uncommon injury diagnosis.     

Recommendations for initial examination,differential diagnosis,and management of concussion and other head injuries in high-level football

Head injuries can result in substantially different outcomes, ranging from no detectable effect to transient functional impairments to life-threatening structural lesions. In high-level international football (soccer) tournaments, on average, one head injury occurs in every third match. Making the diagnosis and determining the severity of a head injury immediately on-pitch or off-field is a major challenge for team physicians, especially because clinical signs of a brain injury can develop over several minutes, hours, or even days after the injury. A standardized approach is useful to support team physicians in their decision whether the player should be allowed to continue to play or should be removed from play after head injury. A systematic, football-specific procedure for examination and management during the first 72 hours after head injuries and a graduated Return-to-Football program for high-level players have been developed by an international group of experts based on current national and international guidelines for the management of acute head injuries. The procedure includes seven stages from the initial on-pitch examination to the graduated Return-to-Football program. Details of the assessments and the consequences of different outcomes are described for each stage. Criteria for emergency management (red flags), removal from play (orange flags), and referral to specialists for further diagnosis and treatment (persistent orange flags) are provided. The guidelines for return to sport after concussion-type head injury are specified for football. Thus, the present paper presents a comprehensive procedure for team physicians after a head injury in high-level football.     

The Football Association Medical Research Programme: an audit of injuries in professional football--analysis of hamstring injuries

OBJECTIVE: To conduct a detailed analysis of hamstring injuries sustained in English professional football over two competitive seasons. METHODS: Club medical staff at 91 professional football clubs annotated player injuries over two seasons. A specific injury audit questionnaire was used together with a weekly form that documented each clubs' current injury status. RESULTS: Completed injury records for the two competitive seasons were obtained from 87% and 76% of the participating clubs respectively. Hamstring strains accounted for 12% of the total injuries over the two seasons with nearly half (53%) involving the biceps femoris. An average of five hamstring strains per club per season was observed. A total of 13 116 days and 2029 matches were missed because of hamstring strains, giving an average of 90 days and 15 matches missed per club per season. In 57% of cases, the injury occurred during running. Hamstring strains were most often observed during matches (62%) with an increase at the end of each half (p<0.01). Groups of players sustaining higher than expected rates of hamstring injury were Premiership (p<0.01) and outfield players (p<0.01), players of black ethnic origin (p<0.05), and players in the older age groups (p<0.01). Only 5% of hamstring strains underwent some form of diagnostic investigation. The reinjury rate for hamstring injury was 12%. CONCLUSION: Hamstring strains are common in football. In trying to reduce the number of initial and recurrent hamstring strains in football, prevention of initial injury is paramount. If injury does occur, the importance of differential diagnosis followed by the management of all causes of posterior thigh pain is emphasised. Clinical reasoning with treatment based on best available evidence is recommended.     

Predictors of time to return to play and re-injury following hamstring injury with and without intramuscular tendon involvement in adult professional footballers: A retrospective cohort study

ObjectivesIn one English Premier League football club over four seasons, 1) describe the number of hamstring strain injuries (HSI) sustained using the British Athletics Muscle Injury Classification (BAMIC); 2) determine if intramuscular tendon HSI influenced the time to return to play (TTRTP) and reinjury rate; 3) determine the predictors of TTRTP and reinjury.DesignRetrospective cohort design.MethodsAll first team players who sustained a HSI between 2014 and 2018 were included. Players underwent an MRI scan that was graded by a Radiologist using the BAMIC (0a-4) criteria. TTRTP, reinjury rate and information on suspected predictors were recorded.ResultsThirty-five HSI experienced by 24 players (age = 26 ± 4 years) were recorded over the 4 seasons. There was a difference in TTRTP between grades 1a and 2c (P = 0.007), but not between 2b and 2c (P = 0.845). Grade of HSI (P ≤ 0.001) and removal of the player (P < 0.001) were predictors of TTRTP, with each increase in grade resulting in an additional 3 days of TTRTP, and being removed, an additional 11 days. Grade and all other predictors did not influence reinjury rate, albeit higher odds were evident for previous HSI, experiencing the HSI during sprinting, passing a ball or stretching, and reported increase days of pain during walking.ConclusionsHSIs extending into the intramuscular tendon (2b cf. 2c) did not influence TTRTP or re-injury, albeit TTRTP was affected by the BAMIC grade and if the player was removed from activity.     

Association between eccentric knee flexor strength and hamstring injury risk in 185 elite Gaelic football players

Hamstring strains are the most common time-loss injury in elite Gaelic football affecting over 20% of players per season. Thus, there is a need to identify factors contributing to the onset of hamstring injuries in order to inform injury risk management strategies. The current study investigated whether eccentric knee flexor strength and between-limb imbalances were associated with increased risk of sustaining a time-loss hamstring injury in elite Gaelic football players. A total of 185 elite male players (26.9 ± 2.7 years, 86.4 ± 6.2 kg, 183.4 ± 5.6) were prospectively followed for 12 weeks from the day of testing. Injury data were provided by the team medical staff. Twenty-eight players (16%) sustained a time-loss hamstring injury following testing. Players that did not sustain a hamstring injury had greater average between-limb asymmetries (uninjured = 9.1%, 95% CI 7.8-10.1; injured = 5.1%, 95% CI 3.7-6.7; P = .001). Eccentric knee flexor strength profiles were not associated with increased or decreased risk of sustaining a hamstring injury and did not alter the post-test probability of sustaining a hamstring injury across the investigation period. These findings do not support the use of eccentric knee flexor strength metrics in managing hamstring injury risk in elite male Gaelic football players.     

The epidemiology of injury for an elite junior Australian Football cohort

ObjectivesTo implement an injury recording protocol in a junior elite Australian Football competition and determine the injury profile of this population.DesignLongitudinal cohort study.MethodsPlayers from an elite Under 18 Australian Football competition were tracked throughout one football season in terms of participation or non-participation in the football competition. Injury reporting forms were collected for all players who were not available for selection as a result of injury.ResultsThe cohort consisted of 532 players who provided consent for inclusion in the study (100% of players in the competition). There were 256 injuries sustained during the season. Results were standardised to a 40 man team to allow comparison with results from the Australian Football League. The injury incidence was 17.1 new injuries per club (95% CI 14.1–19.4), and prevalence 63.3 missed matches per club (95% CI 59.1–67.1). The category “Ankle joint injuries” was the most commonly reported (n = 34) and “Collision with another player” was the main injury mechanism (n = 75).ConclusionsThe most commonly injured region in junior elite Australian Football was the ankle and collision with another player was the most common injury mechanism. As with previous reports on junior Australian Football, injury incidence was low in comparison to the senior elite competition. Defining the injury profile guides injury prevention strategies. Analysis of injury in junior elite football may provide a unique opportunity to affect both junior and senior injury rates.     

Predictors of hamstring injury at the elite level of Australian football

BACKGROUND: Hamstring injuries are the most common injury sustained by elite Australian football players and result in substantial costs because of missed training time, unavailability for matches and lost player payments. Evidence to support proposed risk factors for hamstring injury is generally lacking, limiting the development of appropriate prevention strategies. AIM: To identify intrinsic risk factors for hamstring injury at the elite level of Australian football. METHODS: A prospective cohort of 222 players underwent baseline measurement in the form of a self-report questionnaire and a musculo-skeletal screen during the pre-season period of the 2002 Australian football season. Injury surveillance and exposure data were collected for the full season. Logistic regression analyses were used to identify independent predictors of hamstring injury in this group of players. RESULTS: Thirty-one players sustained a hamstring injury. A past history (previous 12 months) of hamstring injury and increasing age were found to be independent predictors of hamstring injury. CONCLUSIONS: Older players and those with a previous history of hamstring injury are target groups for further research and implementation of injury prevention strategies. Restricted ankle dorsiflexion range of movement warrants consideration in the development of prevention programs for hamstring injury.     

Clinical risk factors for hamstring muscle strain injury: a prospective study with correlation of injury by magnetic resonance imaging

OBJECTIVE: To prospectively establish risk factors for hamstring muscle strain injury using magnetic resonance imaging (MRI) to define the diagnosis of posterior thigh injury. METHOD: In a prospective cohort study using two elite Australian Rules football clubs, the anthropometric characteristics and past clinical history of 114 athletes were recorded. Players were followed throughout the subsequent season, with posterior thigh injuries being documented. Hamstring intramuscular hyperintensity on T2 weighted MRI was required to meet our criteria for a definite hamstring injury. Statistical associations were sought between anthropometric and previous clinical characteristics and hamstring muscle injury. RESULTS: MRI in 32 players showed either hamstring injury (n = 26) or normal scans (n = 6). An association existed between a hamstring injury and each of the following: increasing age, being aboriginal, past history of an injury to the posterior thigh or knee or osteitis pubis (all p<0.05). These factors were still significant when players with a past history of posterior thigh injury (n = 26) were excluded. Previous back injury was associated with a posterior thigh injury that looked normal on MRI scan, but not with an MRI detected hamstring injury. CONCLUSIONS: Hamstring injuries are common in Australian football, and previous posterior thigh injury is a significant risk factor. Other factors, such as increasing age, being of aboriginal descent, or having a past history of knee injury or osteitis pubis, increase the risk of hamstring strain independently of previous posterior thigh injury. However, as the numbers in this study are small, further research is needed before definitive statements can be made.     

The value of MRI STIR signal intensity on return to play prognosis and reinjury risk estimation in athletes with acute hamstring injuries

ObjectivesPrevious studies have shown low to moderate evidence for a variety of magnetic resonance imaging (MRI) features as prognostic factors in athletes with hamstring injuries. Short-tau inversion recovery (STIR) signal intensity has not yet been investigated for assessing the prognosis of acute muscle injuries. Our aim was to explore the relationship between MRI STIR signal intensity and time to return to play (RTP) and to investigate the association between MRI STIR and reinjury risk in athletes with acute hamstring injuries.Study designCase-control study.MethodsWe used MRI STIR to measure intramuscular signal intensity in patients with clinically diagnosed hamstring injuries at two time points: at injury and RTP. At injury, we calculated the association of MRI STIR signal intensity with the time to RTP and reinjury risk. At RTP, the association of MRI STIR signal intensity and reinjury risk and the change in MRI STIR signal intensity over time on reinjury risk was evaluated.Results51 patients were included. We found increased MRI STIR signal intensity: (1) at time of injury not to be associated with time to RTP, (2) at time of injury to be associated with a slightly lower risk for reinjury: odds 0.986 (0.975–0.998, p = 0.02) and (3) at RTP not to be associated with reinjury risk. (4) We found no association between the change in MRI STIR signal intensity over time and reinjury risk.ConclusionIncreased MRI STIR signal intensity at injury has no value in time to RTP prognosis, but is associated with a reduced reinjury risk.     

Drill design using the ’control-chaos continuum’: Blending science and art during return to sport following knee injury in elite football

Establishing the level of risk, planning and adapting the return to sport (RTS) process following a complex knee injury involves drawing on a combination of relevant high-quality evidence and practitioner experience. On-pitch rehabilitation is a critical element of this process, providing an effective transition from rehabilitation to team training. The ‘control-chaos continuum’ (CCC) is an adaptable framework for on-pitch rehabilitation moving from high control to high chaos, progressively increasing running load demands and incorporating greater perceptual and neurocognitive challenges within sport-specific drills. Drills are a key element of the CCC, and are designed to ensure specificity, ecological validity and maintaining player interest. We showcase drill progression through the phases of the CCC, highlighting the use of constraints to create drills that incorporate the physical, technical, tactical and injury-specific needs of the player. We also provide recommendations to help practitioners create training session content using the CCC to help replicate the demands of team training within their own environment.     

Hamstring injuries in England and Wales elite men's domestic cricket from 2010 to 2019

ObjectivesDescribe hamstring injury incidence across competition formats, activity at time of injury, and time of season, facilitating the identification of injury risk factors in elite men's senior First-Class County Cricket.DesignProspective cohort.MethodsHamstring time loss injury incidence (between format, activity, and time of season) calculated for elite men's senior First-Class County Cricket seasons 2010 to 2019.ResultsThe diagnosis with the highest seasonal incidence was ‘Biceps femoris strain grade 1–2’ (2.5 injuries/100 players). Hamstring injury incidence was highest in One-Day cricket (mean 27.2 injuries/1000 team days). Running between wickets when batting was the activity associated with the highest incidence in the shorter competition formats (8.4 and 4.8 injuries/1000 team days for One-Day and T20, respectively). Bowling delivery stride or follow through was the activity with the highest incidence for longer multi-day Test format (mean 2.3 injuries/1000 team days), although similar incidence was observed across all formats for this activity. Most injuries were sustained at the start of the season (April; 22.7 injuries/1000 team days), with significantly fewer injuries at end of the season (September; 4.1 injuries/1000 team days).ConclusionsSimilar bowling injury incidence across formats suggests hamstring injury risk is associated more with the activity itself, whereas injury risk when batting was susceptible to changes in match intensity. The notably higher (albeit non-significant) incidence in April may allude to a lack of preparedness to meet the physical demands of the start of the season. The findings have practical relevance for practitioners, identifying potential opportunities for preventative strategies.     

Incidence, risk, and prevention of hamstring muscle injuries in professional rugby union

BACKGROUND: The incidence of hamstring muscle injuries in professional rugby union is high, but evidence-based information on risk factors and injury-prevention strategies in this sport is limited. PURPOSE: To define the incidence, severity, and risk factors associated with hamstring muscle injuries in professional rugby union and to determine whether the use of hamstring strengthening and stretching exercises reduces the incidence and severity of these injuries. STUDY DESIGN: Cohort study (prevention); Level of evidence, 3. METHODS: Team clinicians reported all hamstring muscle injuries on a weekly basis and provided details of the location, diagnosis, severity, and mechanism of each injury; loss of time from training and match play was used as the definition of an injury. Players' match and training exposures were recorded on a weekly basis. RESULTS: The incidence of hamstring muscle injuries was 0.27 per 1000 player training hours and 5.6 per 1000 player match hours. Injuries, on average, resulted in 17 days of lost time, with recurrent injuries (23%) significantly more severe (25 days lost) than new injuries (14 days lost). Second-row forwards sustained the fewest (2.4 injuries/1000 player hours) and the least severe (7 days lost) match injuries. Running activities accounted for 68% of hamstring muscle injuries, but injuries resulting from kicking were the most severe (36 days lost). Players undertaking Nordic hamstring exercises in addition to conventional stretching and strengthening exercises had lower incidences and severities of injury during training and competition. CONCLUSION: The Nordic hamstring strengthening exercise may reduce the incidence and severity of hamstring muscle injuries sustained during training and competition.     

Relationship between interchange usage and risk of hamstring injuries in the Australian Football League

ObjectivesTo study risk factors for hamstring injury in the Australian Football League (AFL), in particular the effect of recent changes in match participation (increased use of the interchange bench) on hamstring injury.DesignAnalysis of hamstring match injury statistics extracted from an injury database combined with match participation statistics extracted from a player statistics database.Methods56,320 player matches in the AFL over the period 2003–2010 were analyzed, in which 416 hamstring injuries occurred.ResultsIn a Generalized Estimating Equation (GEE) analysis accounting for clustering of different teams, significant predictors of hamstring injuries were recent hamstring injury (RR 4.16, 95% CI 3.19–5.43), past history of ACL reconstruction (RR 1.69, 95% CI 1.09–2.60), past history of calf injury (RR 1.58, 95% CI 1.37–1.82), opposition team making 60 or more interchanges during the game (RR 1.38, 95% CI 1.12–1.68) and player having made 7 or more interchanges off the field in the last 3 weeks (protective RR 0.74, 95% CI 0.59–0.93).ConclusionsThese findings suggest that regular interchanges protect individual players against hamstring injuries, but increase the risk of hamstring injury for opposition players. These findings can be explained by a model in which both fatigue and average match running speed are risk factors for hamstring injury. A player who returns to the ground after a rest on the interchange bench may himself have some short-term protection against hamstring injury because of the reduced fatigue, but his rested state may contribute to increased average running speed for his direct opponent, increasing the risk of injury for players on the opposition team.     

Acute hamstring injuries in Danish elite football: A 12‐month prospective registration study among 374 players

The purpose of the present study was to examine the incidence rates of acute hamstring injuries in Danish elite football sustained during training or match play. Furthermore, it was our intention to document details about the recurrence, severity and the injury seasonal distribution. Hamstring injuries among 374 elite football players were registered prospectively during a 12‐month period. A total of 46 first‐time and eight recurrent hamstring injuries were registered. The incidence rates for incurring a first‐time hamstring injury showed a significantly (P<0.01) greater incidence rate per 1000 h during match play compared with training. Of 32 players who reported a hamstring injury in the 12‐month period before the study, eight (25%) incurred an injury that fulfilled the criteria for a recurrent injury. In 69% of the injuries, the severity of injury was categorized as moderate (8–28 days from injury to injury free) and 18% as severe (>28 days from injury to injury free). Each team sustained a mean of 3.4 hamstring injuries per season, with a mean of 21.5 days missed per injury (range 3–136; median 16 days per injury). The seasonal distribution showed an accumulation of injuries in the first 2 months after a 3.5‐month mid‐season winter break.     

Motor control and strength as predictors of hamstring injury in elite players of Australian football

Objectives. To investigate motor control as a possible contributing factor in hamstring injuries using a test movement similar to the injury-critical phase during running. Leg swing movement discrimination (MD), thigh muscle strength as tested by Cybex isokinetic dynamometry and previous hamstring injury history were all assessed to determine any association with subsequent hamstring injury.Design. Prospective and retrospective observational and analytical cohort study.Setting. A professional football club and a university laboratory.Participants. Twenty elite level players of Australian football.Results. In the 2 years prior to testing, 7 subjects had sustained a hamstring injury. At the time of testing, there were no significant differences between subjects never injured and those previously injured. In the two years following testing, 6 players sustained a hamstring injury. Mean MD score and concentric hamstring-to-quadriceps strength ratio of subsequently injured subjects were significantly worse than those uninjured (p<0.05). Optimum cutoffs on these measures were determined.Conclusion. Both a lower MD ability score for the backward swinging leg and an imbalance of thigh muscle strength were predictive of hamstring injury.     

Evidence based prevention of hamstring injuries in sport

A common soft tissue injury in sports involving sprinting and jumping is the hamstring strain. A major problem with hamstring strains is the high incidence of reinjury. Muscle injuries can be classified as direct or indirect and are typically grouped into three categories according to severity. A number of potential risk factors have been proposed for hamstring strains. Only a few are evidence based and some are mainly based on theoretical assumptions. There is a lack of clinical research on the effectiveness of rehabilitation programmes for hamstring strains. Although the initial treatment of rest, ice, compression, and elevation is accepted for muscle strains, no consensus exists for their rehabilitation. Not much evidence based research has been carried out on prevention of hamstring strain. To our knowledge only two prospective studies have so far been published. As the injuries are common in football and other sports involving sprinting and jumping, there is a need for further research preferably in the form of randomised controlled trials.     

The association football medical research programme: an audit of injuries in professional football

OBJECTIVES: To undertake a prospective epidemiological study of the injuries sustained in English professional football over two competitive seasons. METHODS: Player injuries were annotated by club medical staff at 91 professional football clubs. A specific injury audit questionnaire was used together with a weekly form that documented each club's current injury status. RESULTS: A total of 6,030 injuries were reported over the two seasons with an average of 1.3 injuries per player per season. The mean (SD) number of days absent for each injury was 24.2 (40.2), with 78% of the injuries leading to a minimum of one competitive match being missed. The injury incidence varied throughout the season, with training injuries peaking during July (p<0.05) and match injuries peaking during August (p<0.05). Competition injuries represented 63% of those reported, significantly (p<0.01) more of these injuries occurring towards the end of both halves. Strains (37%) and sprains (19%) were the major injury types, the lower extremity being the site of 87% of the injuries reported. Most injury mechanisms were classified as being non-contact (58%). Re-injuries accounted for 7% of all injuries, 66% of these being classified as either a strain or a sprain. The severity of re-injuries was greater than the initial injury (p<0.01). CONCLUSIONS: Professional football players are exposed to a high risk of injury and there is a need to investigate ways of reducing this risk. Areas that warrant attention include the training programmes implemented by clubs during various stages of the season, the factors contributing to the pattern of injuries during matches with respect to time, and the rehabilitation protocols employed by clubs.     

Readiness for return to sport in non-surgically treated patients with anterior cruciate ligament injury following a public municipal rehabilitation program

ObjectivesTo investigate the proportion of patients that pass a return to sport (RTS) test battery and assess changes in patient-reported outcomes and lower extremity muscle strength following three months of exericse-based rehabilitation in non-surgically treated patients with anterior cruciate ligament (ACL) injury.DesignProspective cohort study.SettingClinical environment (public municipal).ParticipantsThirty-nine ACL injured patients (54% female, median age (IQR) 28 years (24–35).Main outcome measuresThe Knee Injury and Osteoarthritis Outcome Score, Knee Outcome Survey Activities of Daily Living Scale, single hop for distance, crossover hop for distance, side hop test, the Agility T-test, and quadriceps and hamstrings isometric maximal voluntary contraction (MVC).ResultsFollowing 3 months of rehabilitation, patients had statistically significant improvements in all patients-reported outcomes and in quadriceps and hamstring MVC. Of 28 patients who completed all RTS tests, 11% passed six RTS criteria, 14% five criteria, 11% four criteria, 4% three criteria, 18% two criteria, 21% one criterion, and 21% none of the criteria.ConclusionsThe results suggest that three months of public municipal rehabilitation improves patient-reported outcomes and lower extremity muscle strength in non-surgically treated patients with ACL injury. However, only one in every 10 patients passed all RTS criteria.     

Calf injuries in professional football: Treat the patient or the scan? – A case study

ObjectiveTo describe a case of a professional football player with significant imaging findings despite a rather innocuous clinical presentation with gradual onset of calf pain and who was able to continue training and playing with minor medical intervention. To discuss some of the limitations of existing muscle injury grading systems and their potential to cover the full range of injury presentations for calf injuries.DesignCase report.SettingA professional football player was assessed by physical examination, clinical testing and imaging (MRI) after a gradual onset of a calf injury. After returning to training and competition, a follow-up of his symptoms was performed with regular ultrasound imaging assessments.ParticipantA professional football player (35 years, 1.90 m, 88 kg) male, African, striker, playing in the Professional Arabian Gulf League.ConclusionThe discordance between the clinical presentation and the imaging findings resulted in a challenging situation regarding the decision of whether to allow the player to train and compete. In addition, existing muscle injury grading systems do not seem to cover the full range of injuries seen in clinical practice.