Non-contact Lower Extremity Injuries Research Articles

Low back pain or injury before collegiate athletics, a potential risk factor for non-contact athletic injuries.

Majority of research surrounding the predictive value of clinical measurements and assessments for future athletic injury does not differentiate between contact and non-contact injuries. We assessed the association between clinical measures and questionnaire data collected prior to sport participation and the incidence of non-contact lower extremity (LE) injuries among Division III collegiate athletes. Prospective cohort study. University setting, NCAA Division III. 488 Division III freshmen athletes were recruited to participate in the study during their preseason physical examinations. 10,983 public schools. Prospective incidence of non-contact Lower extremity Injury. Athletes completed questionnaires to collect demographics and musculoskeletal pain history. Clinical tests, performed by trained examiners, included hip provocative tests, visual appraisal of a single leg squat to identify dynamic knee valgus, and hip range of motion (ROM). Injury surveillance for each athlete's collegiate career was performed. The athletic training department documented each athlete-reported, new onset injury and documented the injury location, type, and outcome (days lost, surgery performed). Univariable Generalized Estimating Equations (GEE) models were used to analyze the relationship between each clinical measure and the first occurrence of non-contact LE injury. An exchangeable correlation structure was used to account for repeated measurements within athletes (right and left limbs). Of the 488 athletes, 369 athletes (75%) were included in the final analysis. 69 non-contact LE injuries were reported. Responding "Yes" to "Have you ever had pain or an injury to your low back" was associated with an increased risk of non-contact LE, odds ratio = 1.59 (95%CI 1.03- 2.45, p=.04). No other clinical measures were associated with increased injury risk. A history of prior low back pain or injury was associated with an increased risk of sustaining a non-contact LE injury while participating in NCAA Division III athletics.

Using a Markerless Motion Capture System to Identify Preinjury Differences in Functional Assessments.

Functional assessments identify biomechanical issues which may indicate risk for injury and can be used to monitor functional recovery after an injury or surgery. Although the gold standard to assess functional movements is marker-based motion capture systems, these are cost prohibitive and have high participant burden. As such, this study was conducted to determine if a markerless motion capture system could detect preinjury differences in functional movements between those who did and did not experience a noncontact lower extremity injury (NCLEI). A three-dimensional markerless motion capture system comprised an area of 3 m × 5 m × 2.75 m was used. Participants were Division I collegiate athletes wearing plain black long-sleeve shirts, pants, and running shoes of their choice. Functional assessments were the bilateral squat, right and left squat, double leg drop vertical jump, static vertical jump, right and left vertical jump, and right and left 5 hop. Measures were recorded once and the first NCLEI was recorded during the first year after measurement. Two-factor analysis of variance models were used for each measure with factors sex and injury status. Preinjury functional measures averaged 8.4 ± 3.4 minutes capture time. Out of the 333 participants recruited, 209 were male and 124 were female. Of those, 127 males (61%) and 92 females (74%) experienced later NCLEI. The most common initial NCLEI was nonanterior cruciate ligament knee injury in 38 females (41.3%) and 80 males (62.0%). Females had decreased flexion and lower valgus/varus displacement during the bilateral squat (p < 0.006). In addition, knee loading flexion for those who were not injured were more than that seen in the injured group, and was more pronounced for injured females (p < 0.03). The markerless motion capture system can efficiently provide data that can identify preinjury functional differences for lower extremity noncontact injuries. This method holds promise for effectively screening patients or other populations at risk of injury, as well as for monitoring pre-/postsurgery function, without the large costs or participant burden.

Biomechanical Risk Factors of Injury-Related Single-Leg Movements in Male Elite Youth Soccer Players

Altered movement patterns during single-leg movements in soccer increase the risk of lower-extremity non-contact injuries. The identification of biomechanical parameters associated with lower-extremity injuries can enrich knowledge of injury risks and facilitate injury prevention. Fifty-six elite youth soccer players performed a single-leg drop landing task and an unanticipated side-step cutting task. Three-dimensional ankle, knee and hip kinematic and kinetic data were obtained, and non-contact lower-extremity injuries were documented throughout the season. Risk profiling was assessed using a multivariate approach utilising a decision tree model (classification and regression tree method). The decision tree model indicated peak knee frontal plane angle, peak vertical ground reaction force, ankle frontal plane moment and knee transverse plane angle at initial contact (in this hierarchical order) for the single-leg landing task as important biomechanical parameters to discriminate between injured and non-injured players. Hip sagittal plane angle at initial contact, peak ankle transverse plane angle and hip sagittal plane moment (in this hierarchical order) were indicated as risk factors for the unanticipated cutting task. Ankle, knee and hip kinematics, as well as ankle and hip kinetics, during single-leg high-risk movements can provide a good indication of injury risk in elite youth soccer players.

Adherence to an Injury Prevention Warm-Up Program in Children's Soccer-A Secondary Analysis of a Randomized Controlled Trial.

This study examined the impact of high adherence to a neuromuscular training (NMT) warm-up on the risk of lower extremity (LE) injuries in children’s soccer. Twenty U11–U14 youth clubs (n = 92 teams, 1409 players) were randomized into intervention (n = 44 teams) and control (n = 48 teams) groups. The intervention group was advised to perform an NMT warm-up 2 to 3 times a week for 20 weeks. Team adherence, injuries, and exposure were registered throughout the follow-up. Primary outcomes were the incidence of soccer-related acute LE injuries and the prevalence of overuse LE injuries. Intervention teams conducted mean 1.7 (SD 1.0) NMT warm-ups weekly through follow-up. The seasonal trend for adherence declined significantly by −1.9% (95% CI −0.8% to −3.1%) a week. There was no difference in the incidence of acute injuries nor the prevalence of overuse LE injuries in high team adherence group (n = 17 teams) compared to controls. However, the risk for acute noncontact LE injuries was 31% lower in the high team adherence group compared to controls (IRR 0.69, 95% CI 0.49 to 0.97). In an efficacy analysis (n = 7 teams), there was a significant reduction of 47% in the rate of noncontact LE injuries (IRR 0.53, 95% CI 0.29 to 0.97). In conclusion, teams conducted NMT warm-up sessions regularly, but with a declining trend. A greater protective effect was seen in teams with the highest adherence to the NMT warm-up.

Concussion in National Football League Athletes Is Not Associated With Increased Risk of Acute, Noncontact Lower Extremity Musculoskeletal Injury.

Background:Impaired neuromuscular function after concussion has recently been linked to increased risk of lower extremity injuries in athletes.Purpose:To determine if National Football League (NFL) athletes have an increased risk of sustaining an acute, noncontact lower extremity injury in the 90-day period after return to play (RTP) and whether on-field performance differs pre- and postconcussion.Study Design:Cohort study, Level of evidence, 3.Methods:NFL concussions in offensive players from the 2012-2013 to the 2016-2017 seasons were studied. Age, position, injury location/type, RTP, and athlete factors were noted. A 90-day RTP postconcussive period was analyzed for lower extremity injuries. Concussion and injury data were obtained from publicly available sources. Nonconcussed, offensive skill position NFL athletes from the same period were used as a control cohort, with the 2014 season as the reference season. Power rating performance metrics were calculated for ±1, ±2, and ±3 seasons pre- and postconcussion. Conditional logistic regression was used to determine associations between concussion and lower extremity injury as well as the relationship of concussions to on-field performance.Results:In total, 116 concussions were recorded in 108 NFL athletes during the study period. There was no statistically significant difference in the incidence of an acute, noncontact lower extremity injury between concussed and control athletes (8.5% vs 12.8%; P = .143), which correlates with an odds ratio of 0.573 (95% CI, 0.270-1.217). Days (66.4 ± 81.9 days vs 45.1 ± 69.2 days; P = .423) and games missed (3.67 ± 3.0 vs 2.9 ± 2.7 games; P = .470) were similar in concussed athletes and control athletes after a lower extremity injury. No significant changes in power ratings were noted in concussed athletes in the acute period (±1 season to injury) when comparing pre- and postconcussion.Conclusion:Concussed, NFL offensive athletes did not demonstrate increased odds of acute, noncontact, lower extremity injury in a 90-day RTP period when compared with nonconcussed controls. Immediate on-field performance of skill position players did not appear to be affected by concussion.

Neuromuscular Training Warm-up Prevents Acute Noncontact Lower Extremity Injuries in Children's Soccer: A Cluster Randomized Controlled Trial.

Background:Prevention of sports injuries is essential in youth, as injuries are associated with less future physical activity and thus greater all-cause morbidity.Purpose:To investigate whether a neuromuscular training warm-up operated by team coaches is effective in preventing acute lower extremity (LE) injuries in competitive U11-U14 soccer players.Study Design:Randomized controlled trial; Level of evidence, 1.Methods:Twenty top-level U11 to U14 soccer clubs in Finland were randomized into intervention and control groups and assessed for 20 weeks. Participants included 1403 players (280 female, 1123 male; age range, 9-14 years): 673 players (44 teams) in the intervention group and 730 players (48 teams) in the control group. The intervention group team coaches were introduced to a neuromuscular training warm-up to replace the standard warm-up 2 to 3 times per week. The control teams were asked to perform their standard warm-up. Injury data collection was done via weekly text messages. The primary outcome measure was a soccer-related acute LE injury, and the secondary outcome measure was an acute noncontact LE injury.Results:A total of 656 acute LE injuries occurred: 310 in the intervention group and 346 in the control group. The overall acute LE injury incidence was 4.4 per 1000 hours of exposure in the intervention group and 5.5 per 1000 hours of exposure in the control group, with no significant difference between groups (incidence rate ratio [IRR], 0.82 [95% CI, 0.64-1.04]). There were 302 acute noncontact LE injuries: 129 in the intervention group (incidence, 1.8 per 1000 hours) and 173 in the control group (2.7 per 1000 hours). A significant reduction in acute noncontact LE injuries of 32% (IRR, 0.68 [95% CI, 0.51-0.93]) was observed in the intervention group compared with the control group. Furthermore, significant reductions in injury incidence in favor of the intervention group were seen in the subanalyses of acute noncontact LE injuries, leading to ≤7 days of time loss and fewer ankle and joint/ligament injuries.Conclusion:A neuromuscular training warm-up operated by team coaches was found to be effective in preventing acute noncontact LE injuries in children’s soccer, but this was not seen in all acute LE injuries.Clinical Relevance:We encourage children’s soccer coaches and health care professionals to implement neuromuscular training warm-up in youth sports.Registration:ISRCTN14046021 (ISRCTN registry).

Can the Y balance test identify those at risk of contact or non-contact lower extremity injury in adolescent and collegiate Gaelic games?

ObjectivesLower extremity (LE) injuries are common in Gaelic games and lead to a significant economic and injury burden. Balance is considered a predictor of injury in other sports, however no research has examined its effect on LE injury in Gaelic games. This study aims to present normative data for the Y Balance Test (YBT), determine whether the YBT can identify those at risk of contact and non-contact LE and ankle injuries and generate population specific cut-off points in adolescent and collegiate Gaelic games. DesignProspective cohort study. MethodsA convenience sample of 636 male adolescent (n=293, age=15.7±0.7 years) and collegiate (n=343, age=19.3±1.9 years) Gaelic footballers and hurlers were recruited. The YBT was completed and injuries were assessed at least weekly over one season. Univariate and logistic regression was performed to examine if the YBT can classify those at risk of LE-combined and ankle injuries. ROC curves were used to identify cut-off points. ResultsGaelic players performed poorly in the YBT and between 31-57% of all players were identified as at risk of injury at pre-season using previously published YBT cut-off points. However, poor YBT scores were unable to ascertain those at risk of contact or non-contact LE-combined and ankle injuries with sufficient sensitivity. High specificity was noted for contact LE-combined and non-contact ankle injuries. ConclusionsThe YBT as a sole screening method to classify those at risk of LE and ankle injuries in Gaelic games is questionable. However, the YBT may be a useful preliminary screening tool to identify those not at risk of contact LE-combined or non-contact ankle injury. Generalising published cut-off points from other sports is not supported.

Altered hip control during a standing knee-lift test is associated with increased risk of knee injuries.

A few prospective studies have investigated hip and pelvic control as a risk factor for lower extremity (LE) injuries. The purpose of this study was to investigate whether deficits in hip and lumbopelvic control during standing knee-lift test are associated with increased risk of acute knee and LE injuries in youth team sports. At baseline, 258 basketball and floorball players (aged 12-21years) participated in a standing knee-lift test using 3-dimensional motion analysis. Two trials per leg were recorded from each participant. Peak sagittal plane pelvic tilt and frontal plane pelvic drop/hike were measured. Both continuous and categorical variables were analyzed. New non-contact LE injuries, and match and training exposure, were recorded for 12months. Seventy acute LE injuries were registered. Of these, 17 were knee injuries (eight ACL ruptures) and 35 ankle injuries. Risk factor analyses showed that increased contralateral pelvic hike was significantly associated with knee injury risk when using categorical variable (HR for high vs low group 4.07; 95% CI 1.32-12.6). Furthermore, significant association was found between high lateral pelvic hike angles and ACL injury risk in female players (HR for high vs low group 9.10; 95% CI 1.10-75.2). Poor combined sensitivity and specificity of the test was observed. In conclusion, increased contralateral pelvic hike is associated with non-contact knee injury risk among young team sport players and non-contact ACL injuries among female players. More research to determine the role of pelvic control as a risk factor for knee injuries is needed.

Using Motion Sensor Technology to Manage Risk of Injury in a Strength and Conditioning Program for Female Collegiate Athletes

Background of Study: Females generally have a 6-8 times higher risk for lower extremity injury compared to male counterparts due to biomechanical differences and/or poor landing strategies. In recent years, a great deal of focus has been placed on prevention and reduction of non-contact lower extremity injuries. This has spurred the development of assessment methods to determine how athletes move and tools with which those motions are measured. Efforts have been made to measure and quantify movement strategies, which have given rise to multiple movement tests and measurement devices. One approach is the use of wearable technologies used in conjunction with a movement screening. Objective: Demonstrate a practical approach of using wearable technologies to guide training regimens in a population of female athletes that would be considered at risk for lower extremity injuries. Methods: A cohort of Division I female volleyball athletes were screened using wearable technology then assigned an intervention based on screening results. Comparisons were made between injury rates during the season when the intervention was applied compared to previous seasons. Results: All lower extremity injury rates were reduced after the intervention was applied. Conclusions: The use of wearable technology aids in quantifying movement to then assign a strategic intervention to reduce injuries in an at risk athletic population.

Jump and Landing Biomechanical Variables and Methods: A Literature Review.

Noncontact lower extremity injuries are commonly related to jumping and landing activities. This review presents an overview of relevant biomechanical variables that can be modified in training to improve jumping performance, landing mechanics, and consequently, reduce injury risks. Relevant studies from the last 2 decades in the Compendex, Pubmed, and Scopus databases were considered for this review. Studies related to jumping and landing kinetics, kinematics, injuries, performance, and/or simulation were included. The use of experimental methods as the drop jump landing and jumping countermovement are widely used to measure biomechanical variables. At the same time, there has been a continuous development of simulation models that could present results without the need for testing on human subjects, with the final objective of exploring the limits of an athlete's performance without increasing the risk of any injury. The most common injuries occur in the knee and ankle ligaments and are directly related to joint angles and moments (i.e., torque or joint loading) at the hip, ankle, and knee joints. Jumping and landing biomechanics are considerably different between male and female subjects for different experimental methods and in both cases, these kinematics factors can be improved over shorter- or longer-time training to develop a better landing strategy.

NON-CONTACT ANTERIOR CRUCIATE LIGAMENT AND LOWER EXTREMITY INJURY RISK PREDICTION USING FUNCTIONAL MOVEMENT SCREEN AND KNEE ABDUCTION MOMENT: AN EPIDEMIOLOGICAL OBSERVATION OF FEMALE INTERCOLLEGIATE ATHLETES

Modifiable risk factors associated with non-contact anterior cruciate ligament (ACL) injuries are highly debated, yet the incidence rate of ACL injury continues to increase. Measures of movement quality may be an effective method for identifying individuals who are at a high risk of injury. The purpose of this study was to investigate whether a movement screen and/or a drop-jump landing (DJL) task identifies female individuals at a higher risk for sustaining non-contact lower extremity (LE) injuries, particularly ACL injuries. Cohort study. 187 women (mean age 19.5 ± 1.21 years) who played collegiate soccer, volleyball, or basketball completed the Functional Movement Screen (FMS™) and a drop-jump landing task. Weekly injury reports of participants who sustained a non-contact LE injury were collected. FMS™ scores (both total score and individual screens) and Knee Abduction Moment (KAM) values from the DJL task, were compared between injured and uninjured sample populations. A statistically significant difference (t = 1.98, p = 0.049) was observed in the FMS™ scores between the injured (ACL and LE injury) and uninjured groups. Prior ACL injury was also a significant predictor of LE injury (OR = 4.4, p = 0.01). The FMS™ can be used to identify collegiate female athletes who are at an increased risk of sustaining a non-contact ACL or LE injury. Female collegiate athletes that score 14 or less on the FMS™ have a greater chance of sustaining a non-contact LE injury than those who score above 14. 3b.

The Effect of Dynamic Balance Performance on Lower Extremity Injury in Division III Football Players

Identifying and implementing evidence based prevention programs present a significant challenge for athletic trainers. Despite encouraging results in research, individual interventions are often specific to a setting or population and dependent on identifying accurate injury risk factors. This practice-based research is an attempt to apply current evidence in prevention to a population of division three football athletes. The clinical staff reviewed national and site-specific injury data and identified lower extremity (LE) injury as the area of focus. Evidence was searched to identify modifiable risk factors and valid measurement tools that could be addressed in our setting. Dynamic balance has been well documented as a risk factor for LE injury and the Y balance test (YBT) has been shown to be an accurate measure of balance and increased risk of injury. The purpose of our investigation was to determine if our population exhibited similar injury rates in those with balance deficits as documented in other settings. We chose the football program within our setting due to the high number of athletes and consistent injuries that occur throughout the season. All returning football athletes were measured for dynamic balance using the YBT during the annual screening process. Injury record keeping through electronic medical record (EMR) system was consistent with current procedures and non-contact LE injuries were analyzed to remove non-modifiable risk factors. Comparisons were made between YBT results and incidence of injury in 46% of our athletes. Statistical analysis revealed no relationship between YBT measurements and LE injury. Our results are contradictory to those reported in recent studies from differing populations. Implementation difficulties and population differences are theorized reasons for our inability to achieve similar results. Clinically, our results underscore the need for clinicians to measure interventions within their own settings to determine usefulness and make the best decision for their patients.

Association between Y Balance Test Performance and Noncontact Lower Extremity Injury in High School Athletes

Association between Y Balance Test Performance and Noncontact Lower Extremity Injury in High School Athletes

Association between the Functional Movement Screen and Noncontact Lower Extremity Injury in Collegiate Football Players

Association between the Functional Movement Screen and Noncontact Lower Extremity Injury in Collegiate Football Players

Footwear Traction and Lower Extremity Noncontact Injury

Football is the most popular high school sport; however, it has the highest rate of injury. Speculation has been prevalent that foot fixation due to high footwear traction contributes to injury risk. Therefore, the purpose of the study was to determine whether a relationship exists between the athlete's specific footwear traction (measured with their own shoes on the field of play) and lower extremity noncontact injury in high school football. For 3 yr, 555 high school football athletes had their footwear traction measured on the actual field of play at the start of the season, and any injury the athletes suffered during a game was recorded. Lower extremity noncontact injury rates, grouped based on the athlete's specific footwear traction (both translational and rotational), were compared. For translational traction, injury rate reached a peak of 23.3 injuries/1000 game exposures within the midrange of translational traction, before decreasing to 5.0 injuries/1000 game exposures in the high range of traction. For rotational traction, there was a steady increase in injury rate as footwear traction increased, starting at 4.2 injuries/1000 game exposures at low traction and reaching 19.2 injuries/1000 game exposures at high traction. A relationship exists between footwear traction and noncontact lower extremity injury, with increases in rotational traction leading to a greater injury rate and increases in translational traction leading to a decrease in injury. It is recommended that athletes consider selecting footwear with the lowest rotational traction values for which no detriment in performance results.

Field‐expedient screening and injury risk algorithm categories as predictors of noncontact lower extremity injury

In athletics, efficient screening tools are sought to curb the rising number of noncontact injuries and associated health care costs. The authors hypothesized that an injury prediction algorithm that incorporates movement screening performance, demographic information, and injury history can accurately categorize risk of noncontact lower extremity (LE) injury. One hundred eighty-three collegiate athletes were screened during the preseason. The test scores and demographic information were entered into an injury prediction algorithm that weighted the evidence-based risk factors. Athletes were then prospectively followed for noncontact LE injury. Subsequent analysis collapsed the groupings into two risk categories: Low (normal and slight) and High (moderate and substantial). Using these groups and noncontact LE injuries, relative risk (RR), sensitivity, specificity, and likelihood ratios were calculated. Forty-two subjects sustained a noncontact LE injury over the course of the study. Athletes identified as High Risk (n = 63) were at a greater risk of noncontact LE injury (27/63) during the season [RR: 3.4 95% confidence interval 2.0 to 6.0]. These results suggest that an injury prediction algorithm composed of performance on efficient, low-cost, field-ready tests can help identify individuals at elevated risk of noncontact LE injury.

Effect of Neuromuscular Warm-up on Injuries in Female Soccer and Basketball Athletes in Urban Public High Schools

To determine the effectiveness of coach-led neuromuscular warm-up on reducing lower extremity (LE) injuries in female athletes in a mixed-ethnicity, predominantly low-income, urban population. Cluster randomized controlled trial. Chicago public high schools. Of 258 coaches invited to participate, 95 (36.8%) enrolled (1558 athletes). Ninety coaches and 1492 athletes completed the study. We randomized schools to intervention and control groups. We trained intervention coaches to implement a 20-minute neuromuscular warm-up. Control coaches used their usual warm-up. Coach compliance was tracked by self-report and direct observation. Coaches reported weekly athlete exposures (AEs) and LE injuries causing a missed practice or game. Research assistants interviewed injured athletes. Injury rates were compared between the control and intervention groups using χ(2) and Fisher exact tests. Significance was set at P < .05. Poisson regression analysis adjusted for clustering and covariates in an athlete subset reporting personal information (n = 855; 57.3%). There were 28 023 intervention AEs and 22 925 control AEs. Intervention coaches used prescribed warm-up in 1425 of 1773 practices (80.4%). Intervention athletes had lower rates per 1000 AEs of gradual-onset LE injuries (0.43 vs 1.22, P < .01), acute-onset noncontact LE injuries (0.71 vs 1.61, P < .01), noncontact ankle sprains (0.25 vs 0.74, P = .01), and LE injuries treated surgically (0 vs 0.17, P = .04). Regression analysis showed significant incidence rate ratios for acute-onset noncontact LE injuries (0.33; 95% CI, 0.17-0.61), noncontact ankle sprains (0.38; 95% CI, 0.15-0.98), noncontact knee sprains (0.30; 95% CI, 0.10-0.86), and noncontact anterior cruciate ligament injuries (0.20; 95% CI, 0.04-0.95). Coach-led neuromuscular warm-up reduces noncontact LE injuries in female high school soccer and basketball athletes from a mixed-ethnicity, predominantly low-income, urban population. TRIAL REGISTRATION CLINICALTRIALS.ORG IDENTIFIER: NCT01092286.

Hamstring to Quadriceps Strength ratio and Non-contact Leg Injuries: A Prospective Study During one Season

Previous studies have proposed that thigh muscle imbalance is a critical risk factor for the athletic non-contact knee injuries. However, there is a little consensus among prospective studies with regard to the correlation between isokinetic hamstring to quadriceps (H:Q) strength ratio and the non-contact knee injury rates. Most of athletic movements at risk are closed kinetic chain movements, and compensatory effect among ankle, knee, and hip joints during the closed kinetic chain movement was observed in the previous literatures. Therefore, it is assumed that H:Q imbalance can cause non-contact lower extremity injuries without necessarily causing knee injuries. PURPOSE: To prospectively investigate the relationship between H:Q strength imbalance and overall non-contact lower extremity injuries. A prospective cohort study was conducted on NCAA division III basketball and soccer players during one season. METHODS: A total of eighty-two NCAA Division III athletes (41 female [19.56±1.34 yrs, 68.2±10.84 kg, 166.3±6.78 cm] and 40 male [19.97±1.43 yrs, 75.45±8.23 kg, 173.21±7.65 cm]) volunteered to participate in this study. Isokinetic dynamometer was used to assess H:Q strength balance at an angular velocity of 60°/s. RESULTS: The result of a chi-square test showed a trend (p < 0.05) that lower than 60% of H:Q was associated with non-contact leg injuries. CONCLUSION: This suggests that research and prevention strategies of athletic non-contact leg injuries require holistic examination. Consideration of bi-articulate nature of the lower leg muscles and compensatory roles between joints will give us more insights regarding non-contact leg injury mechanism and future preventative strategies.

Hamstring to quadriceps strength ratio and noncontact leg injuries: A prospective study during one season

Previous studies have proposed that thigh muscle imbalance is a critical risk factor for the athletic non-contact knee injuries. However, there is a little consensus among prospective studies with regard to the correlation between isokin etic hamstring to quadriceps strength ratio (HQR) and the non-contact knee injury rates. Most of athletic movements at risk are closed kinetic chain movements, and compensatory effect among ankle, knee, and hip joints during the closed kinetic chain movement was observed in the previous literatures. Therefore, it is a ssumed that hamstrings and quadriceps (H:Q) imbalance can cause non-contact lower extremity injuries without necessarily causing knee injuries. The purpose of this study was to prospectively investigate the relationship between H:Q strength imbalance and overall non-contact lower extremity injuries. A prospective cohort study was conducted on NCAA division III basketball and soccer players during one season. A total of eighty two NCAA Division III athletes (41 female (19.56 ± 1.34 yrs, 68.2 ± 10.84 kg, 166.3 ± 6.78 cm) and 40 male (19.97 ± 1.43 yrs, 75.45 ± 8.23 kg, 173.21 ± 7.65 cm)) volunteered to participate in this study which tested Q and H strength at 60 � /s. A trend (p < 0.05) indicating that lower than 60% of HQR was associated with non-contact leg injuries was apparent. This suggests that the H:Q imbalance may be of significance in athletic non-contact leg injuries.

Whole body, long-axis rotational training improves lower extremity neuromuscular control during single leg lateral drop landing and stabilization

Background Poor neuromuscular control during sports activities is associated with non-contact lower extremity injuries. This study evaluated the efficacy of progressive resistance, whole body, long-axis rotational training to improve lower extremity neuromuscular control during a single leg lateral drop landing and stabilization. Methods Thirty-six healthy subjects were randomly assigned to either Training or Control groups. Electromyographic, ground reaction force, and kinematic data were collected from three pre-test, post-test trials. Independent sample t-tests with Bonferroni corrections for multiple comparisons were used to compare group mean change differences (P ≤ 0.05/21 ≤ 0.0023). Findings Training group gluteus maximus and gluteus medius neuromuscular efficiency improved 35.7% and 31.7%, respectively. Training group composite vertical–anteroposterior–mediolateral ground reaction force stabilization timing occurred 1.35 s earlier. Training group knee flexion angle at landing increased by 3.5°. Training group time period between the initial two peak frontal plane knee displacements following landing increased by 0.17 s. Training group peak hip and knee flexion velocity were 21.2°/s and 20.1°/s slower, respectively. Time period between the initial two peak frontal plane knee displacements following landing and peak hip flexion velocity mean change differences displayed a strong relationship in the Training group (r 2 = 0.77, P = 0.0001) suggesting improved dynamic frontal plane knee control as peak hip flexion velocity decreased. Interpretation This study identified electromyographic, kinematic, and ground reaction force evidence that device training improved lower extremity neuromuscular control during single leg lateral drop landing and stabilization. Further studies with other populations are indicated.