Association between preseason functional tests and injuries in youth football: A prospective follow-up

Correlation between the biomechanical characteristics and stability of the 143D movement during the balance phase in competitive Tai Chi

Objective

To explore the biomechanical factors affecting the stability of athletes in the 143D balance phase of competitive Tai Chi.

Method

The Vicon 3D motion capture system, Kistler 3D force platform, and Noraxon surface electromyography (sEMG) system were used to measure the joint angle, joint moment, center of gravity, ground reaction force, and sEMG data of athletes. The stability index was then calculated according to the formula. Pearson's or Spearman's correlation tests were used to analyze the associations between the biomechanical factors and stability index.

Results

(1) Medial lateral stability index (MLSI): A significant negative correlation was found between the ankle inversion angle of the supporting leg (SL) and MLSI (p < 0.05). (2) Anterior posterior stability index (APSI): Significant negative correlations were observed between the ankle intorsion angle, integrated electromyography (iEMG) of the gastrocnemius, and muscle contribution rates of the tibialis anterior, external oblique, and gastrocnemius of the non-supporting leg (NL) with the APSI (p < 0.05). The ankle dorsiflexion moment, iEMG of the rectus femoris and tibialis anterior, muscle contribution rate of the biceps femoris, and root mean-squared (RMS) amplitude of the gluteus maximus of the SL also showed significant negative correlations with the APSI (p < 0.05). Strong and significant negative correlations were also identified between the hip intorsion angle, iEMG of the tibialis anterior, and RMS amplitude of the rectus femoris of the NL with the APSI (p < 0.01). Further strong and significant negative correlation was also found between the RMS amplitude of the biceps femoris of the SL and APSI (p < 0.01). The knee extorsion angle of the NL was positively correlated with the APSI (p < 0.05). (3) Dynamic postural stability index (DPSI): The knee adduction angle, iEMG of the tibialis anterior, and RMS amplitude of the erector spinae of the NL were significantly positively correlated with the DPSI (p < 0.05). The knee abduction and hip extension moments of the SL were also significantly positively correlated with the DPSI (p < 0.05).

Conclusion

The ankle inversion angle of the SL impacts left-right stability, while the NL's hip and ankle intorsion angles, knee extorsion angle, and exertion on the core muscle and SL's main muscles, as well as exertion of specific muscles of the NL affect anterior-posterior stability. The hip extension and knee abduction moments of the SL, knee adduction angle, exertion on the tibialis anterior, and activation of the erector spinae of the NL significantly affect the overall stability of an athlete.

Injury Risk in Elite Young Male Soccer Players: A Review on the Impact of Growth, Maturation, and Workload

ABSTRACT

Ribeiro, N, Martinho, DV, Pereira, JR, Rebelo, A, Monasterio, X, Gonzalo-Skok, O, Valente-dos-Santos, J, and Tavares, F. Injury risk in elite young male soccer players: a review on the impact of growth, maturation, and workload. J Strength Cond Res XX(X): 000-000, 2024-The long-term development of young male soccer players involves a prolonged period of significant adjustments, highlighting the importance of studying the complex interaction between dynamic variables, including workload, and inherent elements like growth and maturity. This analysis examines the intricate connections involving the development, maturity, workload, and susceptibility to injuries among adolescent male soccer players. Significantly, these connections become prominent at the peak height velocity (PHV) period, a crucial moment in maturation. Growth rates vary among individuals, and higher rates have been associated with an increased risk of injury in young soccer players, particularly during periods of rapid growth. Identifying possible risk factors and understanding the complex connections between them is crucial to developing specific methods for reducing the risk of injury. Sharing this valuable information with essential stakeholders is crucial for guaranteeing young athletes' comprehensive growth and maturation process. Furthermore, this review emphasizes the immediate need for long-term studies and thorough injury analyses to comprehend better the dynamic interactions that influence injury patterns in young male soccer players. This review will allow practitioners to better understand the main modifiable and nonmodifiable risk factors for injury and provide essential information focusing on practical strategies, facilitating more informed decision making by all stakeholders. The review aims to clarify these complexities and offer crucial insights that can assist in designing and implementing efficient strategies to reduce the risk of injury, specifically for the challenges faced during PHV and within the broader framework of long-term athletic development in young soccer.

Growth, maturation and injuries in high-level youth football (soccer): A mini review

Understanding the challenges football (soccer) players face during adolescence is fundamental to avoid disruptions in their development due to injury. This mini review will describe basic concepts of somatic growth and biological maturity, examine data from 53 prospective epidemiological studies on high-level youth football players and discuss how age, growth and maturity may affect the injury patterns observed. Based on the existing evidence, at least every third player sustains an injury during a football season. The thigh (median for studies of boys: 25%, median for girls: 21%), ankle (b: 18%, g: 30%), knee (b: 17%, g: 18%) and hip/groin (b: 14%, g: 10%) are the body parts injured most often, while muscle strains (b: 31%, g: 25%), sprains (b: 20%, g: 27%) and contusions (b: 17%, g: 16%) are the most common injury types. Injury trends are, however, not consistent throughout adolescence, and players' age, maturity status and position relative to peak height velocity (PHV) have shown to influence the number, type and location of injuries sustained. Despite a high volume of observational injury studies published on high-level youth players, girls (7 studies) and settings outside of Europe (included in 23% of studies) are underrepresented and should receive extra attention in the future. Based on the available epidemiological data, tailored injury reduction programmes can be considered in youth football, alongside application of general training principles such as progression, variation and individualization which may be especially important during vulnerable phases such as the adolescent growth spurt.

Epidemiology of injuries in male and female youth football players: A systematic review and meta-analysis

BACKGROUND

To conduct a systematic review and meta-analysis of epidemiological data of injuries in male and female youth football players.

METHODS

Searches were performed in MEDLINE/PubMed, Web of Science, Cochrane Library, and SPORTDiscus databases. Studies were considered if they reported injury incidence rate in male and female youth (≤19 years old) football players. Two reviewers (FJRP and ALV) extracted data and assessed trial quality using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement and the Newcastle Ottawa Scale. The Grading of Recommendations Assessment, Development, and Evaluation approach determined the quality of evidence. Studies were combined using a Poisson random effects regression model.

RESULTS

Forty-three studies were included. The overall incidence rate was 5.70 injuries/1000 h in males and 6.77 injuries/1000 h in females. Match injury incidence (14.43 injuries/1000 h in males and 14.97 injuries/1000 h in females) was significantly higher than training injury incidence (2.77 injuries/1000 h in males and 2.62 injuries/1000 h in females). The lower extremity had the highest incidence rate in both sexes. The most common type of injury was muscle/tendon for males and joint/ligament for females. Minimal injuries were the most common in both sexes. The incidence rate of injuries increased with advances in chronological age in males. Elite male players presented higher match injury incidence than sub-elite players. In females, there was a paucity of data for comparison across age groups and levels of play.

CONCLUSION

The high injury incidence rates and sex differences identified for the most common location and type of injury reinforce the need for implementing different targeted injury-risk mitigation strategies in male and female youth football players.

Adiposity as a Risk Factor for Sport Injury in Youth: A Systematic Review

OBJECTIVE

To determine whether high or low adiposity is associated with youth sport-related injury.

DATA SOURCES

Ten electronic databases were searched to identify prospective studies examining the association between adiposity [body mass index (BMI) or body fat] and a future time-loss or medical attention sport-related musculoskeletal injury or concussion in youth aged 20 years and younger. Two independent raters assessed the quality (Downs and Black criteria) and risk of bias (Joanna Briggs Institute Critical Appraisal Tool). Random-effects meta-analyses were used to calculate pooled odds ratio [95% confidence interval (CI)] of injury.

MAIN RESULTS

Of 11 424 potentially relevant records, 38 articles were included with 17 eligible for meta-analyses. In qualitative synthesis, no clear association was identified between adiposity and any sport injury; however, 16/22 studies identified high adiposity as a significant risk factor for lower-extremity injury. Meta-analyses revealed higher BMI in youth with any sport-related injury and lower BMI in youth who developed a bone stress injury (BSI) compared with noninjured controls. The pooled OR (95% CI) examining the association of BMI and injury risk (excluding bone injury) was 1.18 (95% CI: 1.03-1.34). A major source of bias in included articles was inconsistent adjustment for age, sex, and physical activity participation.

CONCLUSIONS

Level 2b evidence suggests that high BMI is associated with greater risk of youth sport injury, particularly lower-extremity injury and excluding BSI or fracture. Although pooled mean differences were low, anthropometric risk of injury seems to be dependent on type and site of injury in youth sport.

Association Between Preseason Fitness Level and Risk of Injury or Illness in Male Elite Ice Hockey Players: A Prospective Cohort Study

BACKGROUND

Little is known about the association between physical fitness and the risk of injury or illness in ice hockey. The least-fit players may be more prone to injury and illness.

PURPOSE

To examine the association between preseason fitness level and injury or illness risk among elite ice hockey players during the regular season.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 133 male ice hockey players in the GET League (the premier professional league in Norway) completed 8 different exercises (40-m sprint, countermovement jump, 3000-m run, squat, bench press, chin-ups, brutal bench, and box jump) at the annual 1-day preseason testing combine. During the 2017-2018 competitive season, the players reported all health problems (acute injuries, overuse injuries, and illnesses) weekly (31 weeks) using the Oslo Sports Trauma Research Center Questionnaire on Health Problems.

RESULTS

Overall, the players reported 191 acute injuries, 82 overuse injuries, and 132 illnesses. The least-fit tercile of players did not report more health problems (mean, 3.0; 95% CI, 2.2-3.8) compared with the most-fit (mean, 3.4; 95% CI, 2.6-4.2) or the medium-fit (mean, 2.7; 95% CI, 1.9-3.5) players. The most-fit players reported more substantial health problems (mean, 2.0; 95% CI, 1.6-2.5) compared with the medium-fit (mean, 1.3; 95% CI, 0.8 -1.8) and least-fit (mean, 1.8; 95% CI, 1.3-2.3) (P = .02) players. There was no association between low physical fitness and number of health problems when comparing the least-fit tercile of the players with the rest of the cohort (P > .05); however, there was an association between low physical fitness and greater severity of all health problems when comparing the least-fit tercile of players to the rest of the cohort after adjusting for time on ice per game, playing position, and age (P = .02).

CONCLUSION

Low physical fitness was not associated with increased rate of injury or illness but was associated with greater severity of all health problems after adjusting for time on ice per game, playing position, and age.

The Role of the Results of Functional Tests and Psychological Factors on Prediction of Injuries in Adolescent Female Football Players

Football is a popular sport among adolescent females. Given the rate of injuries in female footballers, identifying factors that can predict injuries are important. These injuries are often caused by complex reasons. The aim of this study was to investigate if the combination of demographic (age, number of training and match play hours/week), psychosocial (perceived stress, adaptive coping strategies) and physiological factors (functional performance) can predict a traumatic injury in adolescent female footballers. A cohort consisting of 419 female football players aged 13-16 years was established. Baseline questionnaires covered potential risk factors for sport injuries, and measurements included football-related functional performance tests. Data were collected prospectively with a weekly online questionnaire for 52 weeks covering, e.g., injuries, training, and match play hours/week. A total of 62% of the players reported at least one traumatic injury during the 52 weeks. The coping strategy "positive reframing" had the strongest association with the risk of traumatic injuries. The combination of more frequent use of the coping strategy, positive reframing, and high levels of physical performance capacity may prevent a traumatic injury in adolescent female footballers. Coaches are encouraged to adopt both physiological and psychological factors when preventing injuries in young female footballers.

Identification of Neuromuscular Performance Parameters as Risk Factors of Non-contact Injuries in Male Elite Youth Soccer Players: A Preliminary Study on 62 Players With 25 Non-contact Injuries

Introduction: Elite youth soccer players suffer increasing numbers of injuries owing to constantly increasing physical demands. Deficits in neuromuscular performance may increase the risk of injury. Injury risk factors need to be identified and practical cut-off scores defined. Therefore, the purpose of the study was to assess neuromuscular performance parameters within a laboratory-based injury risk screening, to investigate their association with the risk of non-contact lower extremity injuries in elite youth soccer players, and to provide practice-relevant cut-off scores. Methods: Sixty-two elite youth soccer players (age: 17.2 ± 1.1 years) performed unilateral postural control exercises in different conditions, isokinetic tests of concentric and eccentric knee extension and knee flexion (60°/s), isometric tests of hip adduction and abduction, and isometric tests of trunk flexion, extension, lateral flexion and transversal rotation during the preseason period. Non-contact lower extremities injuries were documented throughout 10 months. Risk profiling was assessed using a multivariate approach utilizing a Decision Tree model [Classification and Regression Tree (CART) method]. Results: Twenty-five non-contact injuries were registered. The Decision Tree model selected the COP sway, the peak torque for knee flexion concentric, the functional knee ratio and the path of the platform in that hierarchical order as important neuromuscular performance parameters to discriminate between injured and non-injured players. The classification showed a sensitivity of 0.73 and a specificity of 0.91. The relative risk was calculated at 4.2, meaning that the risk of suffering an injury is four times greater for a player, who has been classified as injured by the Decision Tree model. Conclusion: Measuring static postural control, postural control under unstable condition and the strength of the thigh seem to enable a good indication of injury risk in elite youth soccer players. However, this finding has to be taken with caution due to a small number of injury cases. Nonetheless, these preliminary results may have practical implications for future directions in injury risk screening and in planning and developing customized training programs to counteract intrinsic injury risk factors in elite youth soccer players.

Motor performance is not related to injury risk in growing elite-level male youth football players. A causal inference approach to injury risk assessment

OBJECTIVE

To identify the causal relation between growth velocity and injury in elite-level youth football players, and to assess the mediating effects of motor performance in this causal pathway.

DESIGN

Prospective cohort study.

METHODS

We measured the body height of 378 male elite-level football players of the U13 to U15 age categories three to four months before and at the start of the competitive season. At the start of the season, players also performed a motor performance test battery, including motor coordination (Körperkoordinationstest für Kinder), muscular performance (standing broad jump, counter movement jump), flexibility (sit and reach), and endurance measures (YoYo intermittent recovery test). Injuries were continuously registered by the academies' medical staff during the first two months of the season. Based on the causal directed acyclic graph (DAG) that identified our assumptions about causal relations between growth velocity (standardized to cm/y), injuries, and motor performance, the causal effect of growth velocity on injury was obtained by conditioning on maturity offset. We determined the natural indirect effects of growth velocity on injury mediated through motor performance.

RESULTS

In total, 105 players sustained an injury. Odds ratios (OR) showed a 15% increase in injury risk per centimetre/year of growth velocity (1.15, 95%CI: 1.05-1.26). There was no causal effect of growth on injury through the motor performance mediated pathways (all ORs were close to 1.0 with narrow 95%CIs).

CONCLUSIONS

Growth velocity is causally related to injury risk in elite-level youth football players, but motor performance does not mediate this relation.

Utility of Kinetic and Kinematic Jumping and Landing Variables as Predictors of Injury Risk: A Systematic Review

Purpose

Jump-landing assessments provide a means to quantify an individual’s ability to attenuate ground reaction forces, generate lower limb explosive power and maintain joint alignment. In order to identify risk factors that can be targeted through appropriate training interventions, it is necessary to establish which (scalar) objective kinetic, kinematic, and performance measures are most associated with lower-extremity injury.

Methods

Online searches of MEDLINE, SCOPUS, EBSCOHost, SPORTDiscus and PubMed databases were completed for all articles published before March 2020 in accordance with PRISMA guidelines.

Results

40 articles investigating nine jump-landing assessments were included in this review. The 79% of studies using drop jump (n = 14) observed an association with future injury, while only 8% of countermovement jump studies (n = 13) observed an association with injury risk. The 57% of studies using unilateral assessments found associations with risk of injury (n = 14). Studies using performance measures (jump height/distance) as outcome measure were only associated with injury risk in 30% of cases. However, those using kinetic and/or kinematic analyses (knee abduction moment, knee valgus angle, knee separation distance, peak ground reaction force) found associations with injury in 89% of studies.

Conclusion

The landing element of jump-landing assessments appears to be superior for identifying individuals at greater risk of injury; likely due to a closer representation of the injury mechanism. Consequently, jump-landing assessments that involve attenuation of impact forces such as the drop jump appear most suited for this purpose but should involve assessment of frontal plane knee motion and ground reaction forces.

Effects of Aerobic and Anaerobic Fatigue Exercises on Postural Control and Recovery Time in Female Soccer Players

Sixteen female soccer players (age = 20.19 ± 1.52 years; body mass = 56.52 ± 4.95 kg; body height = 164.81 ± 4.21 cm) with no history of lower extremity injury participated in the study. The Biodex SD Balance system was used to determine the non-dominant single-leg stability. In anaerobic exercise, each subject performed four maximal cycling efforts against a resistance equivalent to 0.075 kg/body mass for 30 s with three-minute rest intervals. In aerobic exercise, subjects performed the Bruce protocol on a motorized treadmill. After each exercise, subjects subsequently performed a single-leg stability test and then repeated the same test for four times with five-minute passive rest periods. In accordance with the results, it was found that the impairment observed right after the aerobic loading was higher (p < 0.001) compared to the anaerobic one. However, the time-related deterioration in both aerobic and anaerobic loadings was similar. The B-pre value was lower than B_post and B₅ (p < 0.01) and B₁₀ (p < 0.05) in both conditions. Subjects could reach the initial balance level at B₁₅ after aerobic and anaerobic loadings. The lactate level did not reach resting value even after 20 min of both fatigue protocols. Although the fatigue after aerobic and aerobic exercise negatively affects a single-leg dynamic balance level, single leg balance ability returns to the baseline status after 10 min of passive recovery duration.

Are Functional Movement Screen Tests Performed at the Right Time, if It Is an Injury Risk Predictor?

CONTEXT

Sports injuries are more common when players are fatigued and occur more frequently at the end of matches; therefore, determining the right time for employing an injury screening test is important.

OBJECTIVE

To determine the role of timing (prematch vs postmatch fatigue) on the functional movement screen (FMS) scores, a frequently used injury risk screening method.

DESIGN

Cross-sectional study.

SETTING

Field.

PARTICIPANTS

Twenty-four women soccer players from a professional team were included.

MAIN OUTCOME MEASURES

The players were evaluated with a visual analog scale for perceived fatigue and with the FMS. Assessments were conducted before and after a 60-minute match.

RESULTS

The subtest scores for deep squat, hurdle line, in-line lunge, trunk stability push-up, and the total FMS scores showed a significant decrease following the match (P < .05). Compared with prematch, the number of players who could achieve the highest score of 3/3 postmatch was lower for all subtests except right shoulder mobility.

CONCLUSIONS

Our results suggest a negative relationship between perceived fatigue level and performance on the deep squat, hurdle line, in-line lunge, and trunk stability push-up subtest scores and in the total FMS score. Therefore, the authors suggest that screening tests such as the FMS should be employed following a match when players present with fatigue.

Improving predictor selection for injury modelling methods in male footballers

Objectives

This objective of this study was to evaluate whether combining existing methods of elastic net for zero-inflated Poisson and zero-inflated Poisson regression methods could improve real-life applicability of injury prediction models in football.

Methods

Predictor selection and model development was conducted on a pre-existing dataset of 24 male participants from a single English football team's 2015/2016 season.

Results

The elastic net for zero-inflated Poisson penalty method was successful in shrinking the total number of predictors in the presence of high levels of multicollinearity. It was additionally identified that easily measurable data, that is, mass and body fat content, training type, duration and surface, fitness levels, normalised period of 'no-play' and time in competition could contribute to the probability of acquiring a time-loss injury. Furthermore, prolonged series of match-play and increased in-season injury reduced the probability of not sustaining an injury.

Conclusion

For predictor selection, the elastic net for zero-inflated Poisson penalised method in combination with the use of ZIP regression modelling for predicting time-loss injuries have been identified appropriate methods for improving real-life applicability of injury prediction models. These methods are more appropriate for datasets subject to multicollinearity, smaller sample sizes and zero-inflation known to affect the performance of traditional statistical methods. Further validation work is now required.

Effects of a multifactorial injuries prevention program in young Spanish football players

BACKGROUND

The high injury rate in football has highlighted the need to research strategies that allow the modification of the dynamic risk factors. Most of the preventive proposals have focused on standardized protocols. However, the aim of this study was to evaluate the effect of a multifactorial injuries prevention program (MC-7) in Spanish football players.

METHODS

A total of 219 Spanish football male players aged 16-23 were enrolled. The study was conducted over two consecutive seasons (2012-2013, 2013-2014). The first season was the control season (SC) and the second one was the experimental season (ES). Injuries were recorded prospectively during the two seasons in accordance with the criteria established by the consensus statement. During CS the injuries were just observed, while during ES, the players participated in the MC-7: training methodology, specific warm-up protocol (FIFA 11+), basic injury recovery strategies, continuous training of coaches, conferences for parents/family and education sessions for players.

RESULTS

The frequency of injuries was significantly reduced by 63.8% in the ES. Muscle-tendon and joint injuries were reduced by 65% and 56.7% respectively, with a significant decrease in the lower-limbs injuries. The incidence of injuries was reduced by 71.4%, with significant differences in the typology, location and severity of injuries.

CONCLUSIONS

The rate of injury in football is reduced when multifactorial strategies are applied. Reducing the frequency and severity of injuries allowed players to greatly increase their available for sports practice.

Muscle Strength Is a Poor Screening Test for Predicting Lower Extremity Injuries in Professional Male Soccer Players: A 2-Year Prospective Cohort Study

BACKGROUND

Lower extremity muscle strength tests are commonly used to screen for injury risk in professional soccer. However, there is limited evidence on the ability of such tests in predicting future injuries.

PURPOSE

To examine the association between hip and thigh muscle strength and the risk of lower extremity injuries in professional male soccer players.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Professional male soccer players from 14 teams in Qatar underwent a comprehensive strength assessment at the beginning of the 2013/2014 and 2014/2015 seasons. Testing consisted of concentric and eccentric quadriceps and hamstring isokinetic peak torques, eccentric hip adduction and abduction forces, and bilateral isometric adductor force (squeeze test at 45°). Time-loss injuries and exposure in training and matches were registered prospectively by club medical staff throughout each season. Univariate and multivariate Cox regression analyses were used to calculate hazard ratios (HRs) with 95% CIs.

RESULTS

In total, 369 players completed all strength tests and had registered injury and exposure data. Of these, 206 players (55.8%) suffered 538 lower extremity injuries during the 2 seasons; acute muscle injuries were the most frequent. Of the 20 strength measures examined, greater quadriceps concentric peak torque at 300 deg/s (HR, 1.005 [95% CI, 1.00-1.01]; P = .037) was the only strength measure identified as significantly associated with a risk of lower extremity injuries in multivariate analysis. Greater quadriceps concentric peak torque at 60 deg/s (HR, 1.004 [95% CI, 1.00-1.01]; P = .026) was associated with the risk of overuse injuries, and greater bilateral adductor strength adjusted for body weight (HR, 0.75 [95% CI, 0.57-0.97; P = .032) was associated with a lower risk for any knee injury. Receiver operating characteristic curve analyses indicated poor predictive ability of the significant strength variables (area under the curve, 0.45-0.56).

CONCLUSION

There was a weak association with the risk of lower extremity injuries for 2 strength variables: greater quadriceps concentric muscle strength at (1) high and (2) low speeds. These associations were too small to identify an "at-risk" player. Therefore, strength testing, as performed in the present study, cannot be recommended as a screening test to predict injuries in professional male soccer.

"I never made it to the pros…" Return to sport and becoming an elite athlete after pediatric and adolescent anterior cruciate ligament injury-Current evidence and future directions

The management of anterior cruciate ligament (ACL) injuries in the skeletally immature and adolescent patient remains an area of controversy in sports medicine. This study, therefore, summarizes and discusses the current evidence related to treating pediatric and adolescent patients who sustain an ACL injury. The current literature identifies a trend towards ACL reconstruction as the preferred treatment option for ACL injuries in the young, largely justified by the risk of further structural damage to the knee joint. Worryingly, a second ACL injury is all too common in the younger population, where almost one in every three to four young patients who sustain an ACL injury and return to high-risk pivoting sport will go on to sustain another ACL injury. The clinical experience of these patients emphasizes the rarity of an athlete who makes it to elite level after a pediatric or adolescent ACL injury, with or without reconstruction. If these patients are unable to make it to an elite level of sport, treatment should possibly be modified to take account of the risks associated with returning to pivoting and strenuous sport. The surveillance of young athletes may be beneficial when it comes to reducing injuries. Further research is crucial to better understand specific risk factors in the young and to establish independent structures to allow for unbiased decision-making for a safe return to sport after ACL injury. Level of evidence V.

Effects of lower extremity injuries on aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function in high school soccer players

[Purpose] The study investigated the effects of lower extremity injuries on aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function in high school soccer players. [Subjects and Methods] The study assessed U High School soccer players (n=40) in S area, South Korea, divided into 2 groups: a lower extremity injury group (n=16) comprising those with knee and ankle injuries and a control group (n=24) without injury. Aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function were compared and analyzed. [Results] Regarding the aerobic exercise capacity test, significant differences were observed in maximal oxygen uptake and anaerobic threshold between both groups. For the anaerobic power test, no significant difference was observed in peak power and average power between the groups; however, a significant difference in fatigue index was noted. Regarding the knee isokinetic muscular test, no significant difference was noted in knee flexion, extension, and flexion/extension ratio between both groups. [Conclusion] Lower extremity injury was associated with reduced aerobic exercise capacity and a higher fatigue index with respect to anaerobic exercise capacity. Therefore, it seems necessary to establish post-injury training programs that improve aerobic and anaerobic exercise capacity for soccer players who experience lower extremity injury.

Effects of Precompetitive Preparation Period on the Isokinetic Muscular Characteristics in World Class Handball Players

Maurelli, O, Bernard, PL, Dubois, R, Ahmaidi, S, and Prioux, J. Effects of precompetitive preparation period on the isokinetic muscular characteristics in world class handball players. J Strength Cond Res 33(4): 1065-1074, 2019-The aim of this study was to describe the effects of 8 weeks of precompetitive preparation period (Pc2P) on the isokinetic muscular characteristics in world-class handball players. Nineteen male professional players (age, 26.6 ± 5.4 years) participated in the study. Two bilateral isokinetic tests of knee joint flexors (H; hamstring) and extensors (Q; quadriceps) were performed before and after Pc2P to determine the peak torque (PT), the mean power (MP), and the ratios (agonist-antagonist, dominant-nondominant, and combined). For the PT, Q at low angular velocity (60°·s) in concentric mode revealed no significant increase for the dominant or nondominant legs. For H, results showed a significant increase for both legs (p < 0.001). At the higher angular velocity (240°·s), Q was significantly increased for the dominant (p < 0.005) and nondominant (p < 0.002) legs and also H for both sides (p < 0.001). Eccentric mode (30°·s) showed a significant increase for dominant (p < 0.005) and nondominant (p < 0.01) legs. For MP, results showed significant increase at low angular velocity (p < 0.003) and high angular velocity (p < 0.01) for both legs. In eccentric mode, values showed a significant increase after Pc2P for dominant (p < 0.001) and nondominant (p < 0.02) legs. The ratios showed significant increase for the agonist-antagonist ratio at 60°·s for dominant leg (p < 0.003) and the nondominant leg (p < 0.01). At 240°·s, the values showed a significant difference for both side (p < 0.02). From an injury risk perspective, in addition to optimizing performance, these results demonstrated that 8 weeks of Pc2P increased the maximum strength and muscle power of international handball players, even if the ratios of the knee joint muscles did not change during this period.

Preseason Aerobic Fitness Predicts In-Season Injury and Illness in Female Youth Athletes

Background:

Although preseason aerobic fitness has been suggested as a modifiable risk factor for injury in adult athletes, the relationship between aerobic fitness, injury, and illness in youth athletes is unknown.

Purpose:

To determine whether preseason aerobic fitness predicts in-season injury and illness risk in female adolescent soccer players.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Fifty-four female adolescent soccer players underwent preseason evaluation to determine years of experience, body mass index (BMI), maximal aerobic capacity (VO_2max), and time to exhaustion (T_max) during cycle ergometer testing. All injuries and illnesses during the subsequent 20-week season were recorded. Variables were compared between individuals with and without a self-reported injury and individuals with and without a self-reported illness. Separate Poisson regression models were developed to predict number of injuries and illnesses for each individual by use of age, years of experience, BMI, VO_2max, and T_max.

Results:

Twenty-eight injuries and 38 illnesses in 23 individuals were recorded during the season. Although not a statistically significant finding, individuals who reported an in-season injury had lower VO_2max than those who did not (54.9 ± 7.3 vs 58.3 ± 8.5 mL/kg/min, P = .13). Individuals who reported an illness had significantly lower VO_2max than those who did not (54.5 ± 9.9 vs 58.8 ± 6.2 mL/kg/min, P = .014). With the Poisson regression models, VO_2max was a significant predictor of both injury (odds ratio [OR], 0.95; P = .046) and illness (OR, 0.94; P = .009), while no significant relationships were identified between injury or illness and age, years of experience, T_max, or BMI (all P > .05).

Conclusion:

Among adolescent female soccer players, greater preseason aerobic fitness is associated with a reduced risk of in-season injury and illness. Off-season intervention to promote aerobic fitness may help reduce the risk of lost time during the season due to injury and illness.

Perceptions of football players regarding injury risk factors and prevention strategies

Current approaches regarding injury prevention focus on the transfer of evidence into daily practice. One promising approach is to influence attitudes and beliefs of players. The objective of this study was to record player’s perceptions on injury prevention. A survey was performed among players of one German high-level football (soccer) club. 139 professional and youth players between age 13 and 35 years completed a standardized questionnaire (response rate = 98%). It included categories with (1) history of lower extremity injuries, (2) perceptions regarding risk factors and (3) regularly used prevention strategies.

The majority of players (84.2%) had a previous injury. 47.5% of respondents believe that contact with other players is a risk factor, followed by fatigue (38.1%) and environmental factors (25.9%). The relevance of previous injuries as a risk factor is differently perceived between injured (25%) and uninjured players (0.0%). Nearly all players (91.5%) perform stretching to prevent injuries, followed by neuromuscular warm up exercises (54.0%). Taping is used by 40.2% of previously injured players and 13.6% of players without a history of injuries. In conclusion, the perception of risk factors and performed preventive strategies are inconsistent with scientific evidence. Future transfer strategies should incorporate the players beliefs and attitudes.

Timing of Lower Extremity Injuries in Competition and Practice in High School Sports

Background:

Laboratory-based experiments demonstrate that fatigue may contribute to lower extremity injury (LEI). Few studies have examined the timing of LEIs during competition and practice, specifically in high school athletes across multiple sports, to consider the possible relationship between fatigue and LEIs during sport events.

Hypothesis:

The purpose of this study was to describe the timing of LEIs in high school athletes within games and practices across multiple sports, with a hypothesis that more and severe injuries occur later in games and practices.

Study Design:

Descriptive epidemiologic study.

Level of Evidence:

Level 4.

Methods:

Using the National High School RIO (Reporting Information Online) sport injury surveillance system, LEI severity and time of occurrence data during practice and competition were extracted for 9 high school sports.

Results:

During the school years 2005-2006 through 2013-2014, 16,967,702 athlete exposures and 19,676 total LEIs were examined. In all sports surveyed, there was a higher LEI rate, relative risk for LEI, and LEI requiring surgery during competition than practice. During practice, the majority of LEIs occurred over an hour into practice in all sports. In quarter-based competition, more LEIs occurred in the second (31% to 32%) and third quarters (30% to 35%) than in the first (11% to 15%) and fourth quarters (22% to 26%). In games with halves, the majority (53% to 66%) of LEIs occurred in the second half. The greater severity LEIs tended to occur earlier in games.

Conclusion:

Fatigue may play a role in the predominance of injuries in the second half of games, though various factors may be involved. Greater severity of injuries earlier in games may be because of higher energy injuries when athletes are not fatigued.

Clinical Relevance:

These findings can help prepare sports medicine personnel and guide further related research to prevent LEIs.

Functional Assessment and Injury Risk in a Professional Soccer Team

At the last World Conference on Sport and Physical Therapy celebrated in Bern (Switzerland, 2015), it was confirmed that the functional skills of an athlete are a very important variable to be considered in the recovery of an injury. On the other hand, its use as a predictive risk tool still lacks solid evidence. The purpose of this study was to determine whether a battery of functional tests (FPT) could be used as a preliminary measure for the season in order to identify the injury risk in a professional soccer team in the Spanish Second Division B League. Fifty-two soccer players (ages of 25.3 ± 4.6 years, 10.33% ± 0.9% fat) were functionally assessed during two seasons (2012–2013 and 2013–2014) and analyzed from an injury perspective. A total of 125 injuries were recorded. The sample was grouped based on the number of injuries and the required absence days. Except for the bipodal vertical jump (CMJ), none of the functional tests revealed differences among the groups. The correlation study between the functional condition and the suffered injuries did not show any significant results.

Longitudinal Study Evaluating Postural Balance of Young Athletes

Repeated anaerobic conditions during athletic performance may cause general and local fatigue that result in postural balance deficit. Evidence suggests that improved postural balance during athletic training may decrease the risk for fallings and traumatic injuries among athletes. Twenty athletes (12 girls, 8 boys) and 20 controls (12 girls, 8 boys) ages 10–15 years participated in the current study. All athletes were active in an 8-month physical activity program, 3 times per week for 90 min., specific to basketball, soccer, or athletic training. The control children participated in physical education at school only, with no involvement in organized extracurricular sports. All participants were evaluated for postural balance in three assessments over one year (at 4-mo intervals); the Interactive Balance System machine (Tetrax device) was used to assess balance at three test times (pre-, post-, and 10 min) after a session of a repeated sprint anaerobic test, consisting of 12 × 20 m run starting every 20 sec. The athletes had better postural balance than controls. There were different group patterns of change over the sessions; a significant interaction of session and group indicated that postural balance of the groups differed. The contribution of low sway frequencies (F1) and high sway frequencies (F6) differed between the controls and the athletes group. Results suggested that although athletes had better postural balance, improvement should be encouraged during training over the sessions and seasons, with special awareness of the balance deficit that occurs immediately after anaerobic stress and at the end of the season, to decrease the risk of injuries.

Fatigue-induced balance impairment in young soccer players

CONTEXT

Although balance is generally recognized to be an important feature in ensuring good performance in soccer, its link with functional performance remains mostly unexplored, especially in young athletes.

OBJECTIVE

To investigate changes in balance induced by fatigue for unipedal and bipedal static stances in young soccer players.

DESIGN

Crossover study.

SETTING

Biomechanics laboratory and outdoor soccer field.

PATIENTS OR OTHER PARTICIPANTS

Twenty-one male soccer players (age = 14.5 ± 0.2 years, height = 164.5 ± 5.6 cm, mass = 56.8 ± 6.8 kg).

INTERVENTION(S)

Static balance was assessed with postural-sway analysis in unipedal and bipedal upright stance before and after a fatigue protocol consisting of a repeated sprint ability (RSA) test (2 × 15-m shuttle sprint interspersed with 20 seconds of passive recovery, repeated 6 times).

MAIN OUTCOME MEASURE(S)

On the basis of the center-of-pressure (COP) time series acquired during the experimental tests, we measured sway area, COP path length, and COP maximum displacement and velocity in the anteroposterior and mediolateral directions.

RESULTS

Fatigue increased all sway values in bipedal stance and all values except COP velocity in the mediolateral direction in unipedal stance. Fatigue index (calculated on the basis of RSA performance) was positively correlated with fatigue/rest sway ratio for COP path length and COP velocity in the anteroposterior and mediolateral directions for nondominant single-legged stance.

CONCLUSIONS

Fatigued players exhibited reduced performance of the postural-control system. Participants with better performance in the RSA test appeared less affected by balance impairment, especially in single-legged stance.

Effects of knee injury primary prevention programs on anterior cruciate ligament injury rates in female athletes in different sports: a systematic review

BACKGROUND

Anterior Cruciate Ligament (ACL) injury is frequently encountered in sports.

PURPOSE

To analyze the effects of ACL injury prevention programs on injury rates in female athletes between different sports.

METHODS

A comprehensive literature search was performed in September 2012 using Pubmed Central, Science Direct, CINAHL, PEDro, Cochrane Library, SCOPUS, SPORTDiscus. The key words used were: 'anterior cruciate ligament', 'ACL', 'knee joint', 'knee injuries', 'female', 'athletes', 'neuromuscular', 'training', 'prevention'. The inclusion criteria applied were: (1) ACL injury prevention training programs for female athletes; (2) Athlete-exposure data reporting; (3) Effect of training on ACL incidence rates for female athletes.

RESULTS

13 studies met the inclusion criteria. Three training programs in soccer and one in handball led to reduced ACL injury incidence. In basketball no effective training intervention was found. In season training was more effective than preseason in ACL injury prevention. A combination of strength training, plyometrics, balance training, technique monitoring with feedback, produced the most favorable results.

CONCLUSION

Comparing the main components of ACL injury prevention programs for female athletes, some sports-dependent training specificity issues may need addressing in future studies, related primarily to the individual biomechanics of each sport but also their most effective method of delivery.