A comparative video analysis of hamstring injuries mechanism and situational pattern in men's and women's football (soccer).

PURPOSE: To describe the injury mechanism and situational patterns of severe (absence >28 days) hamstring muscle injuries in professional male and female football (soccer) players. METHODS: The data for males were sourced from Serie A clubs participating in both national and international competitions from 2018 to 2021. For the female cohort, hamstring injuries were identified during matches of the top national/international competitions from 2017 to 2023. Video footage was obtained, and three raters categorised injury mechanisms and situational patterns. Injuries were also examined according to the month, minute and location. RESULTS: A total of 129 severe hamstring injuries were identified, with 64 occurring in females and 65 in males. Video analysis was possible for 29 (45%) female cases and 61 (94%) male cases. Female injuries had longer lay-off times (97.8 ± 77.1 days) than males (39.6 ± 20.9 days). Females had a higher proportion of indirect contact injuries (34%) than males (13%) and a lower proportion of non-contact injuries (66% vs. 87%). Four situational patterns were identified: running was the most common for both sexes, representing 59% of female injuries and 41% of male injuries. Over-stretching injuries were split across open and CKC scenarios but collectively explained nearly half (48%) of male injuries but only one in five (21%) female injuries. Kicking injuries had a higher proportion in females (17%) than males (10%). Injuries were more common in the second half for females and the first half for males. CONCLUSION: Females had a higher proportion of indirect contact, running and kicking injuries and a lower proportion of non-contact and stretch-type injuries than males. Understanding injury patterns can inform tailored prevention programs, considering sex-specific differences. LEVEL OF EVIDENCE: Level IV.

The Acute Effects of a Preload Upper-Body Power Exercise on 50-m Freestyle Performance in Youth Swimmers.

ABSTRACT: Hill, V, Patterson, S, Buckthorpe, M, and Legg, HS. The acute effects of a preload upper-body power exercise on 50-m freestyle performance in youth swimmers. J Strength Cond Res 38(7): 1295-1299, 2024-This study aimed to investigate the acute effects of a medicine ball slam and the optimal recovery time required to induce a postactivation performance enhancement (PAPE) response on 50-meter freestyle swimming performance. Twenty-four (13 female, 11 male) competitive, adolescent swimmers (mean ± SD: age, 16.7 ± 1.2 years; height, 173.3 ± 6.7 cm; mass, 63.1 ± 6.4 kg) participated in a randomized crossover study. After the PAPE intervention (3 × 5 medicine ball slams), subjects had 1-minute, 4-minute, and 8-minute recovery periods before a 50-m maximal freestyle swim. A 1-way repeated-measures ANOVA revealed that different recovery times elicited changes in 50-m performance (F = 12.12, p < 0.0005). After 4 minutes of recovery, 50-m performance was 1.6% (0.47 seconds) faster (95% confidence interval [CI] [0.17-0.77], p < 0.001). When the data were split by sex, after 4 minutes of recovery, 50-m performance was 2% (0.64 seconds) faster for women (95% CI [0.279-0.998], p < 0.001). In conclusion, an upper-body power exercise, before performance, can induce a PAPE response and enhance 50-m freestyle performance after a 4-minute recovery period.

Injury mechanisms and situational patterns of severe lower limb muscle injuries in male professional football (soccer) players: a systematic video analysis study on 103 cases.

OBJECTIVE: The objective of this study is to describe the mechanism of injury and situational patterns (based on ball possession and playing action leading to injury) of severe (lay-off time >28 days) lower limb muscle injuries in professional male football (soccer) players during match play. METHODS: Players experiencing a severe muscle injury of the lower limb during Italian first (Serie A) division male football matches over three consecutive seasons (2018-2021) were identified. Video footage was obtained and three raters independently categorised injury mechanism and situational patterns using a standardised checklist. Injury epidemiology (month), timing of injuries within the match and location of injuries on the pitch were also examined. RESULTS: We identified 121 lower limb severe muscle injuries. Videos of sufficient quality were available for 103 (85%) cases, including 61 (60%) hamstring, 17 (16%) calf, 16 (15%) adductor and 9 (9%) quadricep muscle injuries. Nearly two-thirds of injuries involved the dominant/kicking leg (n=65, 63%). Eighty-five (83%) injuries were non-contact and 18 (17%) indirect contact. Four main situational patterns were identified and accounted for 88% of injuries: (1) running/acceleration (n=35, 34%); (2) closed kinetic chain stretching (n=21, 20%); (3) open kinetic chain stretching (n=19, 18%) and (4) kicking (n=16, 16%), with differences between muscle groups. 71% of injuries occurred in the first half of the match (p<0.01), with a gradual increase through the first half. CONCLUSION: Most severe muscle injuries during football matches were non-contact and occurred in the first half during running/acceleration, open and closed kinetic chain stretching, or kicking.

Systematic video analysis of ACL injuries in professional male football (soccer): injury mechanisms, situational patterns and biomechanics study on 134 consecutive cases.

BACKGROUND: A few small studies have reported on the mechanisms of ACL injury in professional male football. AIM: To describe the mechanisms, situational patterns and biomechanics (kinematics) of ACL injuries in professional male football matches. METHODS: We identified 148 consecutive ACL injuries across 10 seasons of professional Italian football. 134 (90%) injury videos were analysed for mechanism and situational pattern, while biomechanical analysis was possible in 107 cases. Three independent reviewers evaluated each video. ACL injury epidemiology (month), timing within the match and pitch location at the time of injury were also reported. RESULTS: 59 (44%) injuries were non-contact, 59 (44%) were indirect contact and 16 (12%) were direct contact. Players were frequently perturbed immediately prior to injury. We identified four main situational patterns for players who suffered a non-contact or an indirect contact injury: (1) pressing and tackling (n=55); (2) tackled (n=24); (3) regaining balance after kicking (n=19); and (4) landing from a jump (n=8). Knee valgus loading (n=83, 81%) was the dominant injury pattern across all four of these situational patterns (86%, 86%, 67% and 50%, respectively). 62% of the injuries occurred in the first half of the matches (p<0.01). Injuries peaked at the beginning of the season (September-October) and were also higher at the end of the season (March-May). CONCLUSIONS: 88% of ACL injuries occurred without direct knee contact, but indirect contact injuries were as frequent as non-contact injuries, underlying the importance of mechanical perturbation. The most common situational patterns were pressing, being tackled and kicking.

Central fatigue contributes to the greater reductions in explosive than maximal strength with high-intensity fatigue.

The study aimed to assess the influence of fatigue induced by repeated high-force explosive contractions on explosive and maximal isometric strength of the human knee extensors and to examine the neural and contractile mechanisms for the expected decrement. Eleven healthy untrained males completed 10 sets of voluntary maximal explosive contractions (five times 3 s, interspersed with 2 s rest). Sets were separated by 5 s, during which supramaximal twitch and octet contractions [eight pulses at 300 Hz that elicit the contractile peak rate of force development (pRFD)] were evoked. Explosive force, at specific time points, and pRFD were assessed for voluntary and evoked efforts, expressed in absolute terms and normalized to maximal/peak force. Maximal voluntary contraction force (MVCF) and peak evoked forces were also determined. Surface EMG amplitude was measured from three superficial agonists and normalized to maximal compound action potential area. By set 10, explosive force (47-52%, P < 0.001) and MVCF (42%, P < 0.001) had declined markedly. Explosive force declined more rapidly than MVCF, with lower normalized explosive force at 50 ms (29%, P = 0.038) that resulted in reduced normalized explosive force from 0 to 150 ms (11-29%, P ≤ 0.038). Neural efficacy declined by 34%, whilst there was a 15-28% reduction in quadriceps EMG amplitude during voluntary efforts (all P ≤ 0.03). There was demonstrable contractile fatigue (pRFD: octet, 27%; twitch, 66%; both P < 0.001). Fatigue reduced normalized pRFD for the twitch (21%, P = 0.001) but not the octet (P = 0.803). Fatigue exerted a more rapid and pronounced effect on explosive force than on MVCF, particularly during the initial 50 ms of contraction, which may explain the greater incidence of injuries associated with fatigue. Both neural and contractile fatigue mechanisms appeared to contribute to impaired explosive voluntary performance.

Neurocognitive Errors and Noncontact Anterior Cruciate Ligament Injuries in Professional Male Soccer Players.

CONTEXT: Evidence is emerging that core neurocognitive functions such as working memory and inhibitory control (ie, motor-response and attentional inhibition) are linked to the anterior cruciate ligament (ACL) injury risk. Research has been conducted in laboratory settings, but the contribution of neurocognition to actual ACL injuries under real-world conditions is unknown. OBJECTIVE: To describe the possible neurocognitive errors involved in noncontact ACL injury mechanisms. DESIGN: Case series. SETTING: Soccer matches. PATIENTS OR OTHER PARTICIPANTS: A total of 47 professional male soccer players. MAIN OUTCOME MEASURE(S): Three independent reviewers evaluated 47 videos of players sustaining noncontact ACL injuries. Neurocognitive errors in inhibitory control were operationalized as follows: (1) motor-response inhibition was scored when a player demonstrated poor decision-making and approached the opponent with high speed that reduced the ability to stop or change the intended action and (2) an attentional error was scored when a player shifted his selective attention away from the relevant task to irrelevant stimuli. RESULTS: Of 47 noncontact ACL injuries, 26 (55%) were related to a pressing-type injury, 19 (73%) of which involved a deceiving action made by the opponent, suggesting poor inhibitory control of the defender. Of the remaining 21 noncontact ACL injuries (45%), 16 (76%) could be attributed to attentional errors. Agreement among the 3 raters was very good for all items except poor decision-making, which showed fair to good agreement (Fleiss κ = 0.71). Interrater reliability was excellent (intraclass correlation coefficient = 0.99-1.00). CONCLUSIONS: Errors in motor-response inhibitory control and attentional inhibition were common during noncontact ACL injury events in professional male soccer players. The interrater agreement in detecting neurocognitive errors in general was very good.

Optimising the Early-Stage Rehabilitation Process Post-ACL Reconstruction.

Outcomes following anterior cruciate ligament reconstruction (ACLR) need improving, with poor return-to-sport rates and a high risk of secondary re-injury. There is a need to improve rehabilitation strategies post-ACLR, if we can support enhanced patient outcomes. This paper discusses how to optimise the early-stage rehabilitation process post-ACLR. Early-stage rehabilitation is the vital foundation on which successful rehabilitation post-ACLR can occur. Without high-quality early-stage (and pre-operative) rehabilitation, patients often do not overcome major aspects of dysfunction, which limits knee function and the ability to transition through subsequent stages of rehabilitation optimally. We highlight six main dimensions during the early stage: (1) pain and swelling; (2) knee joint range of motion; (3) arthrogenic muscle inhibition and muscle strength; (4) movement quality/neuromuscular control during activities of daily living (5) psycho-social-cultural and environmental factors and (6) physical fitness preservation. The six do not share equal importance and the extent of time commitment devoted to each will depend on the individual patient. The paper provides recommendations on how to implement these into practice, discussing training planning and programming, and suggests specific screening to monitor work and when the athlete can progress to the next stage (e.g. mid-stage rehabilitation entry criteria).

Video Analysis of Anterior Cruciate Ligament Injuries in Male Professional Basketball Players: Injury Mechanisms, Situational Patterns, and Biomechanics.

Background: Improving our understanding of the situations and biomechanics that result in an anterior cruciate ligament (ACL) injury in basketball players may support the design of more effective programs to mitigate the risk of injury. Purpose: To (1) describe the mechanisms, situational patterns, and gross biomechanics (kinematics) of ACL injuries in professional basketball matches using video analysis and (2) document the distribution of ACL injuries according to player position, phase of the match, and location on the court. Study Design: Case series; Level of evidence, 4. Methods: A total of 38 ACL injuries in professional male European basketball leagues from the 2013-2014 to 2019-2020 seasons were identified. There were 36 (95%) injury videos analyzed for injury mechanisms and situational patterns, while biomechanical analysis was possible in 32 cases. Overall, 3 independent reviewers evaluated each video. Data according to player position (n = 38), phase of the match (n = 38), and location on the court (n = 36) were evaluated. Results: More injuries occurred while attacking (n = 25 [69%]) than defending (n = 11 [31%]). There was 1 (3%) direct contact injury, 21 (58%) indirect contact injuries, and 14 (39%) noncontact injuries. Most injuries (83%) occurred during 3 main situations: offensive cut (n = 17 [47%]), landing from a jump (n = 8 [22%]), and defensive cut (n = 5 [14%]). Injuries generally involved knee flexion (with minimal hip/trunk flexion and reduced plantarflexion) in the sagittal plane and knee valgus loading in most cases (75%). A similar number of injuries occurred during the first (53%) and second (47%) halves of the match, with a higher prevalence in the second (37%) and fourth (34%) quarters. Half of the injuries occurred during the first 10 minutes of effective playing time. More injuries occurred in guards (58%), and 73% of all injuries occurred in the scoring zone. Conclusion: Indirect contact was the main injury mechanism found in male professional basketball players. The offensive cut was the most common situational pattern. Biomechanical analysis confirmed a multiplanar mechanism, with knee loading in the sagittal plane accompanied by dynamic valgus. More injuries occurred in the first 10 minutes of a player's effective playing time, within the scoring zone, and among guards.

Explosive neuromuscular performance of males versus females.

The purpose of the study was to investigate sex-related differences in explosive muscular force production, as measured by electromechanical delay (EMD) and rate of force development (RFD), and to examine the physiological mechanisms responsible for any differences. The neuromuscular performance of untrained males (n = 20) and females (n = 20) was assessed during a series of isometric knee extension contractions; explosive and maximal voluntary efforts, as well as supramaximal evoked twitches and octets (eight pulses at 300 Hz). Evoked and voluntary EMD were determined from twitch and explosive contractions. The RFD was recorded over consecutive 50 ms time windows from force onset during evoked and explosive contractions, and normalized to maximal strength. Neuromuscular activity during explosive voluntary contractions was measured with EMG of the superficial knee extensors normalized to maximal M-wave. Muscle size (thickness) and muscle-tendon unit (MTU) stiffness were assessed using ultrasonic images of the vastus lateralis at rest and during ramped contractions. Males and females had similar evoked and voluntary EMD. Males were 33% stronger (P < 0.001) and their absolute RFD was 26-56% greater (all time points P < 0.05) compared with females. Muscle size (P < 0.001) and absolute MTU stiffness were also greater for males (P < 0.05). However, normalized RFD was similar for both sexes during the first 150 ms of the explosive voluntary contractions (P > 0.05). This was consistent with the similar normalized twitch and octet RFD, MTU stiffness and agonist EMG (all P > 0.05). When differences in maximal strength were accounted for, the evoked capacity of the knee extensors for explosive force production and the ability to utilize that capacity during explosive voluntary contractions was similar for males and females.

Reliability of neuromuscular measurements during explosive isometric contractions, with special reference to electromyography normalization techniques.

INTRODUCTION: This study determined the between-session reliability of neuromuscular measurements during explosive isometric contractions, with special consideration of electromyography (EMG) normalization. METHODS: Following familiarization, 13 men participated in 3 identical measurement sessions involving maximal and explosive voluntary contractions of the knee extensors, while force and surface EMG were recorded. Root mean square EMG amplitude was normalized to different reference measures: (evoked maximal M-wave peak-to-peak amplitude and area, maximum and sub-maximum voluntary contractions). RESULTS: Explosive voluntary force measurements were reliable on a group level, whereas within-subject reliability was low over the initial 50 ms and good from 100 ms onward. Normalization of EMG during explosive voluntary contractions, irrespective of the reference method, did not reduce the within-subject variability, but it did reduce substantially the variability between-subject. CONCLUSIONS: The high intra-individual variability of EMG and early phase explosive voluntary force production may limit their use to measuring group as opposed to individual responses to an intervention.

Validity of vertical jump measurement devices.

Vertical jump height is thought to provide a valuable index of muscular power, which is an important factor in sports performance and for assessing the mobility and functional capacity of injured or aged individuals. The purpose of the present study was to investigate the criterion validity of four popular devices for measuring vertical jump height. A belt mat, contact mat, portable force plate, and Vertec were compared to a criterion device, a laboratory force plate. Forty participants performed three maximal countermovement jumps on each device in a counterbalanced order, using block randomization. The criterion device presented the highest mean value (50.3 cm). The portable force plate and belt mat devices recorded similar jump height values to the criterion device (within 1 cm). The contact mat and Vertec devices recorded significantly lower values than the criterion device (P < 0.001). The mean difference ± limits of agreement were: belt mat -0.1 ± 5.5 cm, contact mat -11.7 ± 6.4 cm, portable force plate -0.8 ± 3.9 cm, and Vertec -2.4 ± 6.6 cm. In conclusion, the portable force plate and belt mat devices provided valid measures of vertical jump height, whereas the Vertec and contact mat devices did not.

Video analysis of Achilles tendon rupture in male professional football (soccer) players: injury mechanisms, patterns and biomechanics.

Background: Achilles tendon rupture (ATR), while rare in football, is a severe career-threatening injury associated with long-layoff times. To date, no study has documented ATR's mechanism in professional football players. Aim: To describe the mechanisms, situational patterns and gross biomechanics (kinematics) of ATR injuries in professional male football players. Methods: Eighty-six (n=86) consecutive ATR injuries in professional football players during official matches were identified. Sixty (70%) injury videos were identified for mechanism and situational pattern, with biomechanical analysis feasible in 42 cases. Three independent reviewers evaluated the injury videos. Distribution of ATR during the season, the match play and on the field were also reported. Results: Fifty (n=50, 83%) injuries were classified as non-contact and 10 (17%) as indirect contact. ATRs are injuries occurring during accelerations; three main situational patterns were identified: (1) forward acceleration from standing (n=25, 42%); (2) cross-over cutting (n=15, 25%) and (3) vertical jumping (n=11, 18%). Biomechanically, ATR injuries were consistent with a multiplanar loading at the injury frame consisting of a slightly flexed trunk (15.5°), extended hip (-19.5°), early flexed knee (22.5°) and end-range dorsiflexed (40°) ankle in the sagittal plane and foot pronation; 27 (45%) ATRs occurred in the first 30 min of effective match time. Conclusions: All ATRs in professional football were either non-contact (83%) or indirect contact (17%) injuries. The most common situational patterns were forward acceleration from standing, cross-over cutting and vertical jumping. Biomechanics was consistent and probably triggered by a multiplanar, although predominantly sagittal, loading of the injured Achilles tendon.

The exchange of health and performance information when transitioning from club to National football teams: A Delphi survey of National team practitioners.

OBJECTIVES: To establish agreement in National team contexts when players transition from club to National team about (i) what medical and physical information to collect, (ii) how to use information (iii) identifying challenges to collection and (iv) collection methods. DESIGN: Delphi survey. METHODS: A series of sequential online questionnaires were sent to heads of medical and performance of the 32 National teams following the FIFA 2018 World Cup. Two separate Delphi's; 'Medical' and 'Physical' were administered. The 'Medical' respondent was the person responsible for player health. 'Physical' referred to the person responsible for physical performance. Content analyses were performed, with subsequent rounds designed according to responses of the previous. Agreement was considered at ≥70%. RESULTS: Twenty-three Medical (72%) and 14 (44%) Physical heads participated in Round 1 (3 rounds total). Seventeen Medical and 12 Physical respondents completed all rounds. Medical information agreed upon injury epidemiology, screening and injury treatment strategies. Physical information included training/match-loads, fatigue, wellness and current exercise programmes. Both Medical and Physical agreed information should be used to plan and individualise player programmes. Additionally medical information should guide coaches' national team selection. Communication, willingness to share and quality/completeness of information were agreed as main challenges. Medical and Physical respondents agreed a standardised reporting form and electronic shared database as best option to collect information. CONCLUSIONS: Our findings highlight the importance of health and performance information exchange between national and club teams. Further, this exchange should be cooperative, symbiotic and a two-way process to assist with improving player health.

Return to sports after ACL injury 5 years from now: 10 things we must do.

BACKGROUND: The outcome after ACL reconstruction (ACLR) is in general disappointing with unacceptable number of athletes that do not return to pre-injury level of sports, high re-injury rates, early development of osteoarthritis and shorter careers. Athletes after ACLR have high expectation to return to sports which is in contrast with the current outcomes. The aim of this manuscript is to present an overview of factors that are needed to be incorporated and to personalize the rehabilitation process for an athlete who has undergone an ACLR.