Cruciate Ligament Injury Prevention Programs Research Articles

Anterior Cruciate Ligament Injury Prevention Programs in Welsh Netball: A Survey of Knowledge, Implementation and Barriers Amongst Players and Coaches.

Background Anterior cruciate ligament (ACL) injury prevention programs can reduce injury risk in various sports. The perception of ACL injury prevention programs amongst professional netball players and coaches has not been studied. Purpose The aim of this study was to determine (1) the level of awareness and experience of ACL injury prevention programs, (2) the use of ACL injury prevention programs, and (3) barriers and potential facilitators to implementing a sustainable ACL injury prevention program in netball. Materials and methods Female netball players representing Welsh senior and under-21 teams and elite and amateur coaches were invited electronically to participate in this web-based cross-sectional observational study between 1st May and 31st July 2021. Information on ACL injury susceptibility and seriousness, knowledge, experience, and implementation of ACL injury prevention programs were ascertained. Results Twenty-eight players (78%) and 29 coaches (13%) completed the questionnaire. Seventeen (61%) players and 15 (52%) coaches reported that female athletes were at greater risk of sustaining ACL injuries. Over 90% of respondents identified netball as high-risk, whilst 89% (n=25) of players and 76% (n=22) of coaches reported these injuries to be preventable. Only two (7%) players and six (21%) coaches utilised an ACL injury prevention program with a lack of time and engagement from coaches and players identified. The majority of respondents indicated that their club has neither promoted, advocated the use nor demonstrated exercises for ACL injury prevention. Over 90% of respondents would utilise an ACL injury prevention program if it minimised players' risk with appropriate information and demonstration of exercises. Conclusion This study highlights limited knowledge of female athletes' increased susceptibility to ACL injuries amongst players and coaches with a lack of communication and education on ACL injury prevention programs between sporting associations, coaches, and players. However, the results demonstrate willingness amongst both players and coaches to implement an ACL injury prevention program in netball.

Independent data collectors decrease bias in the measurement of adherence to anterior cruciate ligament injury prevention programs

ObjectivesStudies on adherence to neuromuscular training (NMT) for anterior cruciate ligament (ACL) injury prevention are frequently biased due to the use of self-reporting by coaches or the athletes themselves. Few NMT studies use data collectors (aside from the athletes or the individuals administering the NMT program) to decrease bias when assessing the adherence of coaches and sports teams. We hypothesized that the use of a data collector who is independent of the team to evaluate adherence to NMT programs would be reliable. MethodsIn a prior a cluster-randomized controlled trial evaluating adherence to NMT training trial, twelve boys' and nine girls' high school athletic teams in a variety of sports were enrolled. Eight data collectors (unaffiliated with the NMT program) were hired specifically to record adherence of the athletes to the NMT exercises at each team's warm-ups 2–3 times a week, prior to practices and games. In addition to the data collectors, a control group of independent observers made visits throughout the season to also record adherence (solely for the purpose of this study, alongside the data collectors and in the same fashion) in order to evaluate the data collectors' performance and determine inter-observer reliability. The inter-observer reliability between data collectors and independent observers was measured using the Kappa statistic. ResultsA total of 399 warm-ups for practices or games were observed by data collectors to obtain adherence data. Independent observers also measured adherence at 58 practices or games for inter-observer reliability. Exercise instruction and alignment cues for 29 different exercises were analysed. The Kappa values ranged from 0.63 to 1.0, indicating substantial to perfect agreement. The overall Kappa values of 0.89 and 0.90 for exercise instruction and alignment cues, respectively, indicated almost perfect agreement. ConclusionThe use of a data collector who is independent of the team to evaluate adherence to NMT programs (rather than athlete or coach self-reporting), was shown to be a reliable method for measurement of adherence in studies of NMT for injury prevention. Avoiding self-reporting in adherence research to NMT training may decrease bias. Level of EvidenceI.

ANTERIOR CRUCIATE LIGAMENT INJURY PREVENTION PROGRAMMES IN WELSH NETBALL: SURVEY OF KNOWLEDGE, IMPLEMENTATION, AND BARRIERS AMONG PLAYERS AND COACHES

IntroductionAnterior Cruciate Ligament (ACL) injury prevention programs can reduce injury risk in various sports. The perception of ACL injury prevention programs amongst professional netball players and coaches has not been studied. The purpose of the study was to determine (1) level of awareness and experience of ACL injury prevention programs; (2) use of ACL injury prevention programs; and (3) barriers and potential facilitators to implementing a sustainable ACL injury prevention program in netball.MethodsThis cross-sectional observational study was undertaken using the CHERRIES checklist. Female netball players representing Welsh senior and under-21 teams and elite and amateur coaches were invited electronically to participate in this web-based study between 1st May – 31st July 2021. Information on ACL injury susceptibility and seriousness, knowledge, experience, and implementation of ACL injury prevention programs were ascertained.ResultsTwenty-eight players (77.8%) and 29 coaches (13.2%) completed the questionnaire. Seventeen (60.7%) players and 15 (51.7%) coaches reported female athletes were at greater risk for sustaining ACL injuries. Over 90% of respondents identified netball as high-risk, whilst 89% of players and 76% of coaches reported these injuries to be preventable. Only two (7.1%) players and 6 (20.7%) coaches utilised an ACL injury prevention program with lack of time and engagement from coaches and players identified. Majority of respondents indicated that their club has neither promoted, advocated the use nor demonstrated exercises for ACL injury prevention. Over 90% of respondents would utilise an ACL injury prevention program if it minimised players risk with appropriate information and demonstration of exercises.ConclusionThis study highlights limited knowledge of female athletes' increased susceptibility of ACL injuries amongst players and coaches with lack of communication and education of ACL injury prevention programs between sporting associations, coaches, and players. However, the results demonstrate willingness amongst both players and coaches to implement an ACL injury prevention program in netball.

Higher Adherence to Anterior Cruciate Ligament Injury Prevention Programs Is Associated With Lower Injury Rates: A Meta-Analysis and Meta-Regression.

Background: Athletes who participate in sports that involve cutting and pivoting movements are particularly susceptible to anterior cruciate ligament (ACL) injury. Preventing this injury is the best way to combat its health consequences and costs. There may be a dose-response relationship between adherence and injury reduction. Purpose: We sought to examine whether athletes' adherence to injury prevention programs (IPPs) is associated with reductions in ACL and lower extremity (LE) injuries. Methods: We conducted a systematic review of the PubMed, EMBASE, and Cochrane Library databases, searching for studies published between 2011 and 2021. Studies were included if they reported on the use of an ACL IPP compared with a control group and recorded the rate of injuries to calculate a rate ratio, as well as adherence to the program as a percentage of sessions performed. For the meta-analysis, the rate ratios were pooled using the DerSimonian-Laird random-effects model. Results: For the 15 studies included (11 randomized controlled trials and 4 cohort studies), the random-effects model grouped athletes' adherence to an IPP as high (76% or more of the sessions), moderate (51%-75% of the sessions), and low (50% or fewer of the sessions). We found that athletes with the highest level of IPP adherence had a significantly lower incidence of ACL injury. The rate ratios for moderate and low adherence did not demonstrate a reduced incidence of ACL injury. Injury prevention program participation was also associated with a decrease in LE injury rates. Conclusion: This systematic review and meta-analysis found that athletes with high adherence to IPPs had reduced rates of ACL and LE injuries. Our findings suggest that educating coaches and athletes on the dose-dependent benefits of IPPs may promote the routine incorporation of these programs into warm-up sessions to decrease the risk of ACL and LE injuries.

Implementing ACL Injury Prevention in Daily Sports Practice\u2014It\u2019s Not Just the Program: Let\u2019s Build Together, Involve the Context, and Improve the Content

Although the benefits of current anterior cruciate ligament (ACL) injury prevention programmes have been demonstrated in efficacy studies, they, unfortunately, have had limited public health impact to date. For example, the incidence of ACL injuries continues to rise in adolescent athletes. Raising awareness and educating coaches and athletes is not enough to facilitate the widespread, sustained use of these programmes in the real-world setting. Considering the profound burden of ACL injuries, it is necessary to continue to improve the current ACL injury prevention programmes through co-creation. First, the uptake of the programmes should be optimized by a better appreciation and understanding of the individual, socio-cultural and environmental context (i.e., community). Second, the content of the programmes should be optimized to better reflect the demands of the sport by creating more ownership and increasing motivation (incorporating challenging, sport-specific and fun elements) with the end-users. In addition, implicit motor learning, random practice and differential learning are concepts that should be integrated when practising to obtain the most optimal results when learning or finetuning skills.

Coach Education Improves Adherence to Anterior Cruciate Ligament Injury Prevention Programs: A Cluster-Randomized Controlled Trial.

To determine the effect of an educational workshop on adherence to neuromuscular training (NMT) among high-school coaches. Cluster-randomized controlled trial. High school. A total of 21 teams in 8 high schools (unit of randomization) were randomized to the intervention or control group. Twelve boys' and 9 girls' teams in a variety of sports were enrolled. Coaches in the intervention group participated in a 60-minute education workshop to teach effective implementation of a NMT program and also received print materials. Coaches in the control group received the same print materials. Eight data collectors were trained to observe each team's practice/game 2 to 3 times a week. They completed a study questionnaire to identify the NMT exercise and whether the coach (1) delivered exercise instructions and (2) provided alignment cues (both yes/no). A total of 399 practices/games were observed over 2 seasons. A greater proportion of coaches in the intervention group provided alignment cues to correct improper technique compared with the control group {difference = 0.04 [95% confidence interval (CI), 0.01-0.07], P = 0.006}. There was a similar proportion of coaches in the intervention and control groups who provided exercise instructions [difference = 0.01 (95% CI, -0.02 to 0.04), P = 0.44]. More coaches in the intervention group completed a full NMT program [OR = 4.62 (1.22, 17.50), P = 0.02]. Coach education can improve adherence to a NMT program and delivery of alignment cues. Coaches should receive in-person training on NMT and how to deliver alignment cues to their athletes while performing the exercises.

Effects of an Injury Prevention Program on Anterior Cruciate Ligament Injury Risk Factors in Adolescent Females at Different Stages of Maturation

The ideal timing to implement anterior cruciate ligament injury prevention programs with respect to maturation is unclear. The purpose of this study was to investigate the effects of an injury prevention program on knee mechanics in early-, late-, and post-pubertal females. In the study, 178 adolescent female basketball players were assigned to six groups: early-pubertal training, early-pubertal control, late-pubertal training, and late-pubertal control, post-pubertal training, and post-pubertal control. The training groups performed an injury prevention program for six months. Medial knee displacement, knee flexion range of motion, and the probability of high knee abduction moment were assessed before and after the training period. After the six-month training period, medial knee displacement was significantly increased in the early-pubertal control group whereas it was unchanged in the early-pubertal training group. Knee flexion range of motion was significantly decreased in the early-pubertal control group whereas it did not change in the early-pubertal training group. The probability of high knee abduction moment was increased in the early-pubertal control group whereas it was unchanged in the earl-pubertal training group. The probability of high knee abduction moment was also decreased in the post-pubertal training group whereas it did not change in the post-pubertal control group. The program limited the development of high-risk movement patterns associated with maturation in early puberty while improving the knee mechanics in post-pubertal adolescents. Therefore, an injury prevention program should be initiated in early puberty and continue through the post-puberty years.

Comparison Between Soccer and Basketball of Bone Bruise and Meniscal Injury Patterns in Anterior Cruciate Ligament Injuries.

Background:The varying effectiveness of anterior cruciate ligament (ACL) injury prevention programs between soccer and basketball may be due to differences in sport-specific injury mechanisms. Bone bruise patterns may provide information regarding injury mechanisms.Purpose:To compare bone bruise and meniscal injury patterns for ACL injuries sustained in soccer versus basketball.Study Design:Cross-sectional study; Level of evidence, 3.Methods:Clinical notes, operative reports, and magnetic resonance imaging scans were reviewed for patients who sustained a noncontact ACL rupture while playing soccer or basketball between August 2016 and August 2018. The presence, location, and signal intensity of bone bruises on the tibia and femur were documented, and patterns were classified according to the location of the bone bruise in the lateral-medial direction. The meniscal and bone bruise injury patterns and the specific bone bruise locations were compared between the soccer and basketball groups.Results:Overall, 138 patients were included (56 with soccer-related and 82 with basketball-related ACL injury). No significant difference between the groups was observed in bone bruise patterns (P = .743) or meniscal injury patterns (P = .952). Bone bruise on the lateral side only of both the femur and the tibia was the most common pattern in both soccer (41.9%) and basketball (47.0%) groups; the most common meniscal injury type was an isolated lateral meniscal injury in both soccer (50.0%) and basketball (45.0%) groups. For patients with bone bruises on both the lateral and the medial sides of both the femur and the tibia (BF+BT), the bone bruise signal intensity on the lateral side of the femur (P < .001) and tibia (P = .009) was significantly higher than that on the medial side for both groups. The bone bruises on the lateral side of the femur (P < .001) and tibia (P = .002) were significantly more anterior than those on the medial side for patients with the BF+BT pattern.Conclusion:No significant differences in bone bruise location or meniscal injury type were detected when comparing ACL injuries sustained during soccer versus basketball. The study results suggest a similar biomechanical loading pattern for ACL injuries in these sports.

Differences in Knee Shape between ACL Injured and Non-Injured: A Matched Case-Control Study of 168 Patients.

Objective: Anterior cruciate ligament (ACL) injury prevention programs could be more effective if we could select patients at risk for sustaining an ACL rupture. The purpose of this study is to identify radiographic shape variants of the knee between patients with and patients without an ACL rupture. Methods: We compared the lateral and Rosenberg view X-rays of 168 prospectively followed patients with a ruptured ACL to a control group with intact ACLs, matched for gender, after knee trauma. We used statistical shape modeling software to examine knee shape and find differences in shape variants between both groups. Results: In the Rosenberg view X-rays, we found five shape variants to be significantly different between patients with an ACL rupture and patients with an intact ACL but with knee trauma. Overall, patients who had ruptured their ACL had smaller, flatter intercondylar notches, a lower lateral tibia plateau, a lower medial spike of the eminence, and a smaller tibial eminence compared to control patients. Conclusion: Patients with an ACL rupture have smaller intercondylar notches and smaller tibial eminences in comparison to patients with an intact ACL after knee trauma.

Effect of Sand on Landing Knee Valgus During Single-Leg Land and Drop Jump Tasks: Possible Implications for ACL Injury Prevention and Rehabilitation.

Despite significant emphasis on anterior cruciate ligament injury prevention, injury rates continue to rise and reinjury is common. Interventions to reduce injury have included resistance, balance, and jump training elements. The use of sand-based jump training has been postulated as an effective treatment. However, evidence on landing mechanics is limited. To determine potential differences in landing strategies and subsequent landing knee valgus when performing single-leg landing (SLL) and drop jump (DJ) tasks onto sand and land, and to compare between both male and female populations. A randomized repeated-measures crossover design. University laboratory. Thirty-one participants (20 males and 11 females) from a university population. All participants completed DJ and SLL tasks on both sand and land surfaces. Two-dimensional frontal plane projection angle (FPPA) of knee valgus was measured in both the DJ and SLL tasks (right and left) for both sand and land conditions. FPPA was lower (moderate to large effect) for SLL in sand compared with land in both legs (left: 4.3° [2.8°]; right: 4.1° [3.8°]) for females. However, effects were unclear (left: -0.7° [2.2°]) and trivial for males (right: -1.1° [1.9°]). FPPA differences for males and females performing DJ were unclear; thus, more data is required. Differences in FPPA (land vs sand) with respect to grouping (sex) for both SLL left (4.9° [3.0°]) and right (5.1° [4.0°]) were very likely higher (small)/possibly moderate for females compared with males. The effects of sand on FPPA during DJ tasks in males and females are unclear, and further data is required. However, the moderate to large reductions in FPPA in females during SLL tasks suggest that sand may provide a safer alternative to firm ground for female athletes in anterior cruciate ligament injury prevention and rehabilitation programs, which involve a SLL component.

A 2-yr Biomechanically Informed ACL Injury Prevention Training Intervention in Female Field Hockey Players

ABSTRACT Purpose Anterior cruciate ligament (ACL) injury prevention programs have been shown to have mixed success in reducing injury rates, raising the question whether these programs are effectively targeting biomechanical mechanisms of injury. The current study examined the efficacy of a biomechanically informed ACL injury prevention training program in reducing injury risk and injury incidence and investigated its effect on athletic performance. Participants Twenty-six elite female field hockey players participated in this study. Methods Athletes participated in a 2-yr injury prevention training program. Injury incidence (i.e., lower limb and ACL) and athletic performance (i.e., strength, speed, and aerobic power) were measured during a control season and after two intervention seasons. Biomechanical ACL injury risk factors were recorded during unplanned sidestepping at baseline and after intensive (9 wk: 4 × 20 min·wk−1) and maintenance (16 wk: 3 × 10 min·wk−1) training phases for a subset of athletes (n = 17). Results Training was effective in reducing ACL and lower limb injury incidence after the 2-yr program, where zero ACL injuries occurred after implementation (vs 0.4 per 1000 player hours in the control year). High-risk athletes reduced their peak knee valgus moments by 30% (P = 0.045) and demonstrated improvements in desirable muscle activation strategies after intensive training. The majority of benefits elicited in intensive training were retained during the maintenance phase. One-repetition max strength, beep test scores, and sprint times improved or were maintained over the 2-yr intervention period. Conclusions Biomechanically informed injury prevention training was successful in reducing both biomechanical ACL injury risk factors and ACL injury incidence while maintaining and/or improving athletic performance. It is important to consider the biomechanical mechanisms of injury when designing injury prevention programs.

A Majority of Anterior Cruciate Ligament Injuries Can Be Prevented by Injury Prevention Programs: A Systematic Review of Randomized Controlled Trials and Cluster–Randomized Controlled Trials With Meta-analysis

Background: Anterior cruciate ligament (ACL) injury prevention programs (IPPs) are generally accepted as being valuable for reducing injury risk. However, significant methodological limitations of previous meta-analyses raise questions about the efficacy of these programs and the extent to which meeting current best-practice ACL IPP recommendations influences the protective effect of these programs. Purpose: To (1) estimate the protective effect of ACL IPPs while controlling for common methodological limitations of previous meta-analyses and (2) systematically categorize IPP components and factors related to IPP delivery to assess the validity of current best-practice IPP recommendations. Study Design: Systematic review with meta-analysis. Methods: A systematic search of 5 electronic scientific databases was conducted to identify studies testing the efficacy of ACL IPPs. Studies were included if (1) the intervention aimed to prevent ACL injury, (2) the incidence rate (IR) or other outcome data that made it possible to calculate the IR for both the intervention and control groups were reported, and (3) the study design was a prospective randomized controlled trial (RCT) or cluster-RCT. Results: Of the 2219 studies screened, 8 studies were included in the quantitative synthesis, and their analysis revealed a significant reduction in ACL IR when athletes received IPPs (IR ratio = 0.47; 95% CI, 0.30-0.73; P < .001). The majority of included IPPs tended to meet minimum best-practice recommendations and incorporated plyometric, strengthening, and agility exercises along with feedback on proper landing technique. However, the specific exercises included in each IPP and key factors related to IPP delivery were highly variable. Conclusion: Despite limiting the analysis to only high-quality studies and controlling for time at risk and potential clustering effects, the study showed that ACL IPPs had a significant protective effect and reduced injury rates by 53%. However, significant variability in the specific exercises and the manner of program delivery suggests that ACL IPPs may be able to be designed within an overarching best-practice framework. This may allow practitioners the flexibility to develop IPPs that meet the specific characteristics of the target population and potentially increase the likelihood that these programs will be widely adopted and implemented.

Neuromuscular Control of Vertical Jumps in Female Adolescents.

Poor landing mechanics are considered deficits in neuromuscular control and risk factors for lower extremity injury. The Landing Error Scoring System (LESS) has been used to assess the neuromuscular control of landing mechanics for the first landing in a drop vertical jump (DVJ) task. However, the second DVJ landing may provide different results, warranting assessment. (1) LESS scores will differ between first and second DVJ landings across all female participants with (2) greater intraparticipant variability among the second landing compared with the first landing scores. Cross-sectional study. Level 4. A total of 13 gymnasts and 31 softball players (N = 44) performed 3 DVJ trials. The mean ± SD age of 44 female athletes was 16.46 ± 2.59 years. The LESS was scored using 2-dimensional video of each trial. There was a significant difference between the first and second DVJ landings (P < 0.01). All participants demonstrated higher LESS scores (worse landing mechanics) during the second DVJ landing (10.10 ± 2.25) than the first landing (6.97 ± 2.72). The initial landing in a DVJ has been the focus of neuromuscular control studies using the LESS. This study found worse neuromuscular control during the second DVJ landing, which highlights the importance of evaluating landing mechanics beyond the initial landing. LESS analysis of both DVJ landings might improve neuromuscular control screening in female athletes and augment lower extremity and anterior cruciate ligament injury prevention programs.

The Effects of Instruction Exercises on Performance and Kinetic Factors Associated With Lower-Extremity Injury in Landing After Volleyball Blocks.

Female volleyball players are more predisposed to anterior cruciate ligament injury in comparison with their male counterparts. Recent research on anterior cruciate ligament injury prevention strategies has shown the positive results of adopting the external focus (EF) of attention in sports. To determine the effect of 6-week EF instruction exercises on performance and kinetic factors associated with lower-extremity injury in landing after the volleyball blocks of female athletes. Pretest and posttest control study. University research laboratory. Thirty-two female volleyball players (18-24y old) from the same team randomly divided into experimental (n = 16) and control (n = 16) groups. The experimental group performed a 6-week exercise program with EF instructions. The control group continued its regular volleyball team schedule. To assess function, single-leg triple hop test for distance was used. A force plate was used to evaluate kinetic variables including vertical ground reaction forces, the rate of loading, and dynamic postural stability index. All data were assessed at baseline and after the intervention. There was a significant increase in single-leg triple hop test (P < .05) and in the first and second peak ground reaction force, rate of loadings, dynamic postural stability index (P < .05). According to the results of this study, anterior cruciate ligament injury prevention programs should incorporate EF instruction exercises to enhance the kinetics and to increase athletes' functional performance.

Training rugby athletes with an external attentional focus promotes more automatic adaptions in landing forces

ABSTRACT Training to reduce landing forces is a common component of anterior cruciate ligament injury prevention programmes. The purpose of this study was to compare the effects of training incorporating instructions promoting an internal versus external attentional focus on landing forces in adolescent rugby athletes. Twenty-two rugby athletes were randomly allocated to groups that received instructions promoting an internal versus an external focus during a two week training programme. Landing forces were recorded before and after completion of the programme. During follow-up testing, landings were performed with and without a secondary cognitive task. Both groups exhibited a similar reduction in landing forces following training for trials performed without the secondary cognitive task. However, the groups responded differently when the secondary cognitive task was imposed. Athletes who were trained with an internal focus demonstrated a prominent increase in landing forces for trials that included the secondary cognitive task (vs. trials performed without the secondary cognitive task), whereas the secondary cognitive task had minimal influence for athletes who were trained with an external focus. It appears that training with an external focus may promote adaptations in landing mechanics that can be implemented more automatically.

Hip biomechanics differ in responders and non-responders to an ACL injury prevention program.

To investigate the differences in demographic, anthropometric, biomechanical, and/or performance variables between those that do (responders) and do not (non-responders) exhibit reductions in knee abduction moments after an anterior cruciate ligament injury prevention program (ACL-IPP). Forty-three adolescent female athletes completed biomechanical (3D motion analysis of a drop vertical jump) and performance testing before and after randomization into a 6-week ACL-IPP. Participants were classified into responders and non-responders based on their level of reduction of knee abduction moment from pre- to post-test. Compared to non-responders, responders exhibited increased hip adduction excursion at baseline (p = 0.02) and trended towards attending more training sessions (p = 0.07) and participating in soccer and not basketball (p = 0.07). Responders also showed greater improvements in hip flexion angles (p = 0.02) and moments (p < 0.001), and knee abduction angles (p < 0.001) and excursions (p = 0.001). There were no significant differences in age or experience with prior injury prevention programs (n.s.). After anACL-IPP, athletes that exhibit the greatest reduction in knee abduction moments exhibit greater hip adduction excursion at baseline and show corresponding improvements in hip flexion and knee abduction kinematics and hip flexion moments. These results can help clinicians prospectively identify individuals that may not respond to an ACL-IPP and target individualized training for those at risk of injury. I. Clinicaltrials.gov NCT02530333.

Effect of Maturation on Heart Rate During a Six-Week Plyometric Training in Female Soccer Players

Implementation of an anterior cruciate ligament (ACL) injury prevention program (IPP) has been recommended to coincide with the adolescent growth spurt as risk factors increase during and following this phase of maturation. Physiological responses to load during this stage of growth may result in a differing maximum heart rate (HRmax) during intense exercise. Understanding the relationship between physiological responses to load and maturation stage may result in more effective IPP in youth athletes. PURPOSE: To examine the effects of maturation on HRmax in adolescent soccer players over a six-week training program. METHODS: 34 female soccer players participated in a 6-week training study (age 13.3±1.5yrs; height 158.7±6.9cm; mass 50.0±9.6kg). Maturation groups were determined based on percent of adult stature (PAS) with 88-94% representing pubertal (n=9, PAS 91.6±2.0%) and 95-100% representing post-pubertal (n=25, PAS 97.7±1.7%). Three 30 minute sessions, separated into plyometric, resistance, and core strength training, were completed each visit for a total training time of 90 minutes three times per week. Participants wore HR monitors during each plyometric session. The initial exercises were adapted from ACL IPP, and intensity of each exercise was progressed weekly following the second week of training (5 total phases). HRmax was calculated for each participant during each session and averaged weekly. A linear mixed model (p<0.05) was used to determine the effects of HRmax over the six-week intervention in pubertal and post-pubertal female soccer players. Average HR during the first week of training was used as a covariate. RESULTS: A significant interaction of maturational group and training week was found (p<0.04) with HRmax. A main effect of training week was found in both pubertal (p<0.001) and post-pubertal (p<0.01) groups. HRmax was significantly increased in both groups (week 1 to week 3, p<0.05) following the first two technique focused weeks of plyometric program with the pubertal group (184.3±4.7 BPM) having greater HRmax compared to the post-pubertal group (172.7±2.2 BPM) during week 3. CONCLUSIONS: Physiologic responses to load was dependent on maturation stage and should be further examined in relation to reduced risk of injury following IPP. Funding supported by NIAMS/NIH R21AR069873

Sport-specific biomechanical responses to an ACL injury prevention programme: A randomised controlled trial

ABSTRACTAnterior cruciate ligament (ACL) injury prevention programmes have not been as successful at reducing injury rates in women’s basketball as in soccer. This randomised controlled trial (ClinicalTrials.gov #NCT02530333) compared biomechanical adaptations in basketball and soccer players during jump-landing activities after an ACL injury prevention programme. Eighty-seven athletes were cluster randomised into intervention (6-week programme) and control groups. Three-dimensional biomechanical analyses of drop vertical jump (DVJ), double- (SAG-DL) and single-leg (SAG-SL) sagittal, and double- (FRONT-DL) and single-leg (FRONT-SL) frontal plane jump landing tasks were tested before and after the intervention. Peak angles, excursions, and joint moments were analysed using two-way MANCOVAs of post-test scores while controlling for pre-test scores. During SAG-SL the basketball intervention group exhibited increased peak knee abduction angles (p = .004) and excursions (p = .003) compared to the basketball control group (p = .01) and soccer intervention group (p = .01). During FRONT-SL, the basketball intervention group exhibited greater knee flexion excursion after training than the control group (p = .01), but not the soccer intervention group (p = .11). Although women’s soccer players exhibit greater improvements in knee abduction kinematics than basketball players, these athletes largely exhibit similar biomechanical adaptations to ACL injury prevention programmes.

Exploring individual adaptations to an anterior cruciate ligament injury prevention programme

BackgroundIndividual responses to anterior cruciate ligament injury prevention programmes (ACL IPPs) have received little attention. This study examined the effects of an ACL IPP on neuromuscular control and lower limb biomechanics during landing at the group and individual levels. MethodsSixteen female athletes were randomly allocated to training (n=8) or control (n=8) groups. Electromyography, and three-dimensional kinematic and kinetic data were collected during landing at two testing sessions. Repeated measures ANOVA and effect sizes (Cohen's d) examined the effect of the IPP at the group and individual levels. A sub-group analysis comparing the effect of the IPP on ‘high-’ (i.e. large peak knee abduction moment at baseline) versus ‘low-risk’ individuals was also conducted. ResultsAt the group level; the IPP increased activation of the medial hamstrings prior to landing (p<0.001; d=0.264) and the medial gastrocnemius at landing (p<0.001; d=0.426), and increased hip external rotation early after initial contact (p<0.001; d=0.476). Variable adaptations were seen across individuals within the training group for all variables (p<0.001). The IPP had a large effect in reducing frontal plane knee moments for ‘high-risk’ individuals (d>0.91), however these results did not reach statistical significance (p>0.05). ConclusionsThe IPP induced adaptations during landing, however, individual data revealed dissimilar responses to the programme. Individuals displaying a pre-existing high-risk strategy may incur greater benefits from IPPs, yet only if the programme targets the relevant high-risk strategy.

Age Influences Biomechanical Changes After Participation in an Anterior Cruciate Ligament Injury Prevention Program

Background: The prevalence of anterior cruciate ligament (ACL) injuries increases during maturation and peaks during late adolescence. Previous studies suggested an age-related association between participation in injury prevention programs and reduction of ACL injury. However, few studies have investigated differences in biomechanical changes after injury prevention programs between preadolescent and adolescent athletes. Purpose/Hypothesis: The purpose was to investigate the influence of age on the effects of the FIFA Medical and Research Centre (F-MARC) 11+ injury prevention warm-up program on differences in biomechanical risk factors for ACL injury between preadolescent and adolescent female soccer players. It was hypothesized that the ACL injury risk factors of knee valgus angle and moment would be greater at baseline but would improve more after training for preadolescent athletes than adolescent athletes. It was further hypothesized that flexor-extensor muscle co-contraction would increase after training for both preadolescent and adolescent athletes. Study Design: Controlled laboratory study. Methods: Institutional Review Board–approved written consent was obtained for 51 preadolescent female athletes aged 10 to 12 years (intervention: n = 28, 11.8 ± 0.8 years; control: n = 23, 11.2 ± 0.6 years) and 43 adolescent female athletes aged 14 to 18 years (intervention: n = 22, 15.9 ± 0.9 years; control: n = 21, 15.7 ± 1.1 years). The intervention groups participated in 15 in-season sessions of the F-MARC 11+ program 2 times per week. Pre- and postseason motion capture data were collected during 4 tasks: preplanned cutting, unanticipated cutting, double-legged jump, and single-legged jump. Lower extremity joint angles and moments were estimated through biomechanical modeling. Knee flexor-extensor muscle co-contraction was estimated from surface electromyography. Results: At baseline, preadolescent athletes displayed greater initial contact and peak knee valgus angles during all activities when compared with the adolescent athletes, but knee valgus moment was not significantly different between age groups. After intervention training, preadolescent athletes improved and decreased their initial contact knee valgus angle (–1.24° ± 0.36°; P = .036) as well as their peak knee valgus moment (–0.57 ± 0.27 percentage body weight × height; P = .033) during the double-legged jump task, as compared with adolescent athletes in the intervention. Compared with adolescent athletes, preadolescent athletes displayed higher weight acceptance flexor-extensor muscle co-contraction at baseline during all activities (P < .05). After intervention training, preadolescent athletes displayed an increase in precontact flexor-extensor muscle co-contraction during preplanned cutting as compared with adolescent intervention athletes (0.07 ± 0.02 vs –0.30 ± 0.27, respectively; P = .002). Conclusion: The F-MARC 11+ program may be more effective at improving some risk factors for ACL injury among preadolescent female athletes than adolescent athletes, notably by reducing knee valgus angle and moment during a double-legged jump landing. Clinical Relevance: ACL prevention programs may be more effective if administered early in an athlete’s career, as younger athletes may be more likely to adapt new biomechanical movement patterns.