Incidence Of Lower Extremity Injuries Research Articles

Hip and core exercise programme prevents running-related overuse injuries in adult novice recreational runners: a three-arm randomised controlled trial (Run RCT)

ObjectiveThis study aims to investigate the efficacy of two exercise interventions in reducing lower extremity (LE) injuries in novice recreational runners.MethodsNovice runners (245 female, 80 male) were randomised into hip...

Spine Injuries Sustained After Falls While Crossing the U.S.-Mexico Border.

This study is to report the demographics, incidence, and patterns of spinal injuries associated with border crossings resulting from a fall from a significant height. A retrospective cohort study was performed at a Level I trauma center from January 2016 to December 2021 to identify all patients who fell from a significant height while traversing the U.S.-Mexico border and were subsequently admitted. A total of 448 patients were identified. Of the 448 patients, 117 (26.2%) had spine injuries and 39 (33.3%) underwent operative fixation. Females had a significantly higher incidence of spine injuries (60% vs. 40%; p < 0.00330). Patients with a spine fracture fell from a higher median fall height (6.1 vs. 4.6 m; p < 0.001), which resulted in longer median length of stay (LOS; 12 vs. 7 days; p < 0.001), greater median Injury Severity Score (ISS; 20 vs. 9; p < 0.001), and greater relative risk (RR) of ISS >15 (RR = 3.2; p < 0.001). Patients with operative spine injuries had significantly longer median intensive care unit (ICU) LOS than patients with non-operative spine injuries (4 vs. 2 days; p < 0.001). Patients with spinal cord injuries and ISS >15 sustained falls from a higher distance (median 6.1 vs. 5.5 m) and had a longer length of ICU stay (median 3 vs. 0 days). All patients with operative spine injuries had an ISS >15 relative to 50% of patients with non-operative spine injuries (median ISS 20 vs. 15; p < 0.001). Patients with spine trauma requiring surgery had a higher incidence of head (RR = 3.5; p 0.0353) and chest injuries (RR = 6.0; p = 0.0238), but a lower incidence of lower extremity injuries (RR = 0.5; p < 0.001). Thoracolumbar injuries occurred in 68.4% of all patients with spine injuries. Patients with operative spine injuries had a higher incidence of burst fracture (RR = 15.5; p < 0.001) and flexion-distraction injury (RR = 25.7; p = 0.0257). All patients with non-operative spine injuries had American Spinal Injury Association (ASIA) D or E presentations, and patients with operative spine injuries had a higher incidence of spinal cord injury: ASIA D or lower at time of presentation (RR = 6.3; p < 0.001). Falls from walls in border crossings result in significant injuries to the head, spine, long bones, and body, resulting in polytrauma casualties. Falls from higher height were associated with a higher frequency and severity of spinal injuries, greater ISS, and longer ICU length of stay. Operative spine injuries, compared with non-operative spine injuries, had longer ICU length of stay, greater ISS, and different fracture morphology. Spine surgeons and neurocritical care teams should be prepared to care for injuries associated with falls from height in this unique population.

Comparison of foot kinematics and ground reaction force characteristics during walking in individuals with highly and mildly pronated feet

BackgroundIndividuals with highly pronated feet (PF) are more prone to lower extremity injuries than those with mildly PF. However, whether foot kinematics and ground reaction force (GRF) characteristics differ according to the severity of PF deformity is unclear. Research questionAre there differences in foot kinematics and GRF characteristics during walking between individuals with mildly PF and those with highly PF? MethodsTen individuals with mildly PF and 10 with highly PF (six-item foot posture index scores: 6–9 and 10–12 points, respectively) participated in this study. A three-dimensional motion analysis system measured participants’ foot kinematics and GRF characteristics during gait trials. ResultsParticipants with highly PF exhibited significantly lower medial longitudinal arch heights than those with mildly PF from 0 % to 90 % of the stance phase (p < 0.05). No significant differences were observed in any of the angles between the foot segments. Additionally, participants with highly PF exhibited significantly larger posterior GRF than those with mildly PF from 2 % to 7 % of the stance phase (p < 0.05). Participants with highly PF also exhibited significantly larger anterior GRF than those with mildly PF, from 62 % to 82 % of the stance phase (p < 0.05). SignificanceThe results of this study suggest that the more severe the PF deformity, the more inefficient the foot ground force transmission, and the stronger the load applied to the foot. These results may be related to the higher incidence of lower extremity injuries in individuals with highly PF than in those with mildly PF.

The Effect of Ball Heading and Subclinical Concussion On the Neuromuscular Control Of The Lower Limb: A Systematic Review.

Soccer is unique among sports because it is the only sport that involves purposeful use of the head to control, pass, or shoot the ball. Over the previous five years, a relationship between lower extremity (LE) injury and sports related concussion (SRC) has been established in various sporting populations. Athletes at the high school, collegiate, and professional levels have demonstrated a greater risk for sustaining a LE injury post SRC. The purpose of this systematic review was to examine the relationship of the SRC with the incidence of LE injuries. Ten databases were searched with the following keywords: Lower limb, ball heading, neuromuscular control, concussion, MEDLINE, Ovid MEDLINE(R) Daily, and Ovid MEDLINE(R), EMBASE, and Scopus. The search was limited to English-language and peer-reviewed publications, until 15/12/2022. The PEDro scale was used for the assessment of the risk of bias among the included studies. All included papers were qualitatively analyzed. A total of 834 studies were identified and 10 articles (four concussion-MSK biomechanics, six concussion-MSK injury) were included in the qualitative analyses. Included papers ranged from low to high quality. Due to the heterogeneous nature of the included study designs, quantitative meta-analysis was unable to be performed. All four of the included concussion-MSK biomechanics studies demonstrated, to some degree, that worse cognitive performance was associated with lower extremity MSK biomechanical patterns suggestive of greater risk for MSK injury. Among the six injury related studies, two investigations failed to determine group differences in cognitive performance between subsequently injured and non-injured athletes. More research is needed to better understand the relationship of SRC and lower extremity injuries and the extent to which they are related to concussions and/or repetitive neurotrauma after ball heading sustained in soccer. 2.

Association Between Injury History And Incidence Of Lower Extremity Injury During Canada Games Competition

Association Between Injury History And Incidence Of Lower Extremity Injury During Canada Games Competition

Association of Dynamic Knee Valgus and Bone Stress Injury in US Military Academy Cadets.

Early identification of incoming military personnel at elevated odds for bone stress injury (BSI) is important for the health and readiness of the US military. Prospective cohort study. Knee kinematic data of the incoming US Military Academy cadets were collected while performing a jump-landing task (The Landing Error Scoring System) using a markerless motion capture system and depth camera. Data on incidence of lower-extremity injury, including BSI, were collected throughout the study period. A total of 1905 participants (452 females, 23.7%) were examined for knee valgus and BSI status. A total of 50 BSI occurred during the study period (incidence proportion = 2.6%). The unadjusted odds ratio for BSI at initial contact was 1.03 (95% confidence interval [CI], 0.94-1.14; P = .49). Adjusted for sex, the odds ratio for BSI at initial contact was 0.97 (95% CI, 0.87-1.06; P = .47). At the instant of maximum knee-flexion angle, the unadjusted odds ratio was 1.06 (95% CI, 1.02-1.10; P = .01), and the odds ratio was 1.02 (95% CI, 0.98-1.07; P = .29) after adjusting for sex. This suggests that there was not a significant enough association for an increase in the odds of BSI based on either degree of knee valgus. Our results did not demonstrate an association between knee valgus angle data during a jump-landing task and future increased odds of BSI in a military training population. Further analysis is warranted, but the results suggests the association between kinematics and BSI cannot be effectively screened by knee valgus angle data in isolation.

Effect of the COVID-19 Pandemic on Lower Extremity Injuries in Japanese Collegiate Men's Basketball Players.

The coronavirus disease 2019 (COVID-19) pandemic significantly affected the lives of Japanese collegiate men's basketball players. To describe the incidence of lower extremity injuries in Japanese collegiate men's basketball during the COVID-19 pandemic and examine the effects of the pandemic on injury patterns. Descriptive epidemiological study. Using data from a surveillance project of the Department of Medicine and Science of the Kanto Collegiate Basketball Federation, the authors included data from 6 men's basketball teams during the 2020-21 and 2021-22 seasons (11 team seasons). Injury rates per 1000 athlete-exposures (AEs) were calculated according to injury type, location, and frequency. Injury burden was estimated by multiplying the injury rate by the mean days lost. Injuries from the 2020-21 to 2021-22 seasons were compared with those before the pandemic (2013-14 to 2019-20 seasons) using injury rate ratios (IRRs), with significant differences indicated when the 95% CI did not include 1.0. In total, 135 lower extremity injuries were reported during 27,249 AEs. The overall injury rate of the 2020-21 to 2021-22 seasons was significantly higher than that of the 2013-14 to 2019-20 seasons (IRR, 1.37; 95% CI, 1.12-1.67). Lateral ankle sprains (IRR, 1.37; 95% CI, 1.02-1.86), hamstring strains (IRR, 2.86; 95% CI, 1.34-6.12), jumper's knee (IRR, 2.68; 95% CI, 1.13-6.37), and stress fractures of the proximal fifth metatarsal (IRR, 7.16; 95% CI, 1.31-39.08) were significantly higher during the 2020-21 to 2021-22 seasons compared with the 2013-14 to 2019-20 seasons. The rate of lower extremity injuries increased significantly in Japanese collegiate men's basketball players during the COVID-19 pandemic. The results of this study emphasize the importance of optimal screening and specific loads for injury prevention when detraining periods are anticipated.

Examination of overhead and single-leg squat kinematics and lower extremity injury in female collegiate athletes.

Overhead squat (OHS) and single-leg squat (SLS) tests have been used as screening tools to identify injury risk in athletic populations. Yet, no study has examined the association between specific trunk and lower extremity (LE) kinematic measures acquired during OHS and SLS performance and LE injury incidence in female collegiate athletes. The purpose of this study was to examine the association between LE and trunk kinematics captured during OHS and SLS performance and LE injury in female collegiate athletes. This was a prospective cohort study. One hundred eight Division I female collegiate athletes underwent OHS and SLS testing before the start of their competitive season. A Microsoft Kinect sensor using Athletic Movement Assessment software (PhysiMax®) was used to capture kinematic variables: hip flexion, knee flexion, knee frontal plane projection angle (FPPA), and trunk flexion. Participants were tracked during one competitive season for incidence of LE injury. Logistic regression models were used to examine the association between OHS and SLS measures and injury. Twenty-three (21.3%) participants suffered a LE injury. No significant associations were found between any OHS (odds ratio [OR] range: 0.91-1.08) or SLS (OR range: 0.81-1.22) kinematic measure and incidence of LE injury. Sagittal plane LE and trunk kinematics and knee FPPA during OHS and SLS performance were not associated with LE injury in this cohort of athletes. Our findings do not support the use of these select kinematic measures captured during OHS and SLS testing as stand-alone injury risk assessments in female collegiate athletes.

A multicomponent neuromuscular warm-up program reduces lower-extremity injuries in trained basketball players: A cluster randomized controlled trial

Objective To assess the effects of a novel multicomponent neuromuscular warm-up program on lower-extremity injury incidence in basketball players competing at the regional level. Methods : A cluster randomized controlled experimental design was adopted to compare injury incidence between players exposed to the injury prevention warm-up program and those exposed to a typical warm-up program across an entire basketball season. Four teams consisting of 57 players (male: n = 42; female: n = 15) were allocated to the intervention group (age: 21.6 ± 2.5 years; height: 186.2 ± 8.8 cm; body mass: 80.0 ± 10.4 kg) and four teams consisting of 55 players (male: n = 43; female: n = 12) were allocated to the control group (age: 21.6 ± 2.6 years; height: 186.9 ± 9.1 cm; body mass: 81.5 ± 10.9 kg). The novel warm-up combined running exercises with active stretching, plyometrics, balance, strength, and agility drills. Coaching and medical staff provided details on injury incidence each week. Data analyses included the use of poisson regression analyses and the incidence rate ratio (IRR) with 95% confidence intervals (CI). Results The intervention group experienced a significantly lower ankle sprain incidence rate (IRR = 0.26, 95% CI = 0.05, 0.98, p = 0.02) and a tendency toward a lower knee injury incidence rate (IRR = 0.32, 95% CI = 0.03, 1.78, p = 0.07) compared to the control group. Considering only non-contact lower-extremity injuries of any type, the intervention group experienced a significantly lower incidence rate compared to the control group (IRR = 0.26, 95% CI = 0.05, 0.98, p <0.001). Conclusion This multi-team study demonstrated a novel multicomponent warm-up program resulted in less non-contact lower-extremity injuries, particularly ankle sprains and knee injuries, compared to a typical warm-up program in regional-level male and female basketball players.

Increased Knee and Meniscal Injury Incidence in Professional Baseball Pitchers With Wider, Positive Stride Width.

Professional baseball pitchers sustain 75% of knee injuries while at the pitcher's mound, yet no pitching motion has been associated directly with such injuries. Stride width is a potential, modifiable risk factor worth investigating. Increased stride width in both the positive and negative directions (deviations from neutral stride width) would correlate with increased incidence of knee injury in pitchers. Descriptive laboratory. Level 5. Professional pitchers (n = 199) were evaluated with motion capture (480 Hz) while pitching. Injury history over 10 years was recorded at face-to-face interviews with pitchers. Players were subsequently grouped into stride width tertiles, compared for previous injury incidence of the lower extremities. Regressions were performed to observe performance benefits of stride width with ball velocity, accuracy, or consistency in pitch location as secondary outcomes. Of the 40 lower extremity injuries reported, meniscal injury (27.5%) was the most common, followed by foot stress fracture (20.0%). Significant differences in injury incidence were noted between the least and most positive stride width tertiles: lower extremity (10.4% vs 25.8%, respectively; P = 0.03), knee (3.0% vs 15.2%, respectively; P = 0.02), and meniscal (0.0% vs 12.1%; P = 0.00). Stride width of pitchers with meniscal injury in the lead (32.6 ± 7.1 cm, n = 5; P = 0.02) and stance leg (33.5 ± 10.6 cm, n = 5; P = 0.03) was significantly more positive than that of uninjured pitchers (21.1 ± 11.5 cm, n = 164). No significant relationships were established between stride width and ball velocity (P = 0.54) or pitch location metrics (P > 0.05). Pitchers with increased positive, stride width had significantly higher incidence of lower extremity injury (knee and meniscus). Wider, positive stride width may increase the degree of external rotation on the lead knee in a loaded state, which can place the medial side of the knee (and meniscus) at higher risk of injury. Decreasing stride width may be beneficial for professional pitchers to reduce the rate of lower extremity injury, while also preserving performance metric outcomes.

Paper 22: Increased Lower Extremity Injury Associated with Player Load and Distance in Collegiate Women’s Soccer

Objectives:High cumulative workloads and spikes in player workloads have been associated with an increased risk of injury in soccer and other sports. These studies, however, have all been conducted with data from male soccer players or male athletes in other sports, with few studies investigating female athletes. Using metrics collected from GPS units to monitor cumulative load and distance may be valuable for injury prevention. The purpose of this study was to examine the relationship between injury risk and workload as collected from wearable GPS units in NCAA Division I women’s soccer players.Methods:Lower extremity injury incidence and GPS workload data (player load, total distance, and high-speed distance) of 65 NCAA Division I women’s soccer players were collected over 3 seasons. Accumulated 1-, 2-, 3- and 4-weekly loads and acute: chronic workload ratios (ACWR) were classified into discrete ranges by z-scores. ACWR was calculated using rolling averages and exponentially weighted moving averages (EWMA) models. Binary logistic regression models were used to compare the 7:28 rolling average and EWMA ACWRs between injured and non-injured players for all GPS/accelerometer variables. The prior 1-, 2-, 3-, and 4-weekly accumulated loads for all GPS/accelerometer variables were compared between the injured and uninjured cohorts using two-sample t-tests with an alpha level of 0.05 set as significant.Results:There were a total of 53 lower extremity injuries that resulted in lost time recorded (5.76/1000 hours ‘on-field’ exposure time; 34 non-contact and 19 contact injuries). The prior 2-week (7,242 vs 6,613; p=0.02), 3-week (10,533 vs 9,718; p=0.02), and 4-week (13,819 vs 12,892; p=0.04) accumulated player loads and 2-week (62.40 vs 57.25 km; p=0.04), 3-week (90.97 vs 84.10 km; p=0.03), and 4-week (119.31 vs 111.38 km; p=0.05) accumulated total distances were significantly higher for injured players compared to non-injured players during the same timeframes. There were no significant differences in player load, total distance, or high-speed distance ACWR between injured and non-injured players for both the rolling averages and EWMA calculations.Conclusions:Higher accumulated player load and total distance, but not ACWR, are associated with injury in women’s soccer players.

Increased Risk of Musculoskeletal Injuries After Concussion

The incidence of lower extremity injury among athletes returning to play following concussion has been increasingly reported over the past several years. The literature investigating this association is robust and has been reported across sports, levels of competition, and ages. However, the underlying mechanisms for this increased risk of injury are not fully understood. This review will provide a summary of the current literature surrounding the association of concussion and lower extremity injury risk and discuss theories for why this relationship may exist, including lingering deficits that are not detected with common concussion assessments. Further, we will discuss clinical implications for the increased injury risk after concussion, including limitations of traditional concussion evaluation strategies for detecting individuals at high risk for future injury. In addition to discussing current knowledge gaps, we will explore potentially useful assessment strategies that may inform return to play decision making in the context of increased subsequent injury risk.

Increased Lower Extremity Injury Risk Associated With Player Load and Distance in Collegiate Women's Soccer.

Background:There is limited research regarding the impact of workload on injury risk specific to women’s soccer. Wearable global positioning system (GPS) units can track workload metrics such as total distance traveled and player load during games and training sessions. These metrics can be useful in predicting injury risk.Purpose:To examine the relationship between injury risk and player workload as collected from wearable GPS units in National Collegiate Athletic Association (NCAA) Division I women’s soccer players.Study Design:Case-control study; Level of evidence, 3.Methods:Lower extremity injury incidence and GPS workload data (player load, total distance, and high-speed distance) for 65 NCAA Division I women’s soccer players were collected over 3 seasons. Accumulated 1-, 2-, 3-, and 4-week loads and acute-to-chronic workload ratios (ACWR) were classified into discrete ranges by z-scores. ACWR was calculated using rolling averages and exponentially weighted moving averages (EWMA) models. Binary logistic regression models were used to compare the 7:28 rolling average and EWMA ACWRs between injured and noninjured players for all GPS/accelerometer variables. The prior 1-, 2-, 3-, and 4-week accumulated loads for all GPS/accelerometer variables were compared between the injured and uninjured cohorts using 2-sample t tests.Results:There were a total of 53 lower extremity injuries that resulted in lost time recorded (5.76/1000 hours “on-legs” exposure time; 34 noncontact and 19 contact injuries). The prior 2-week (7242 vs 6613 m/s2; P = .02), 3-week (10,533 vs 9718 m/s2; P = .02), and 4-week (13,819 vs 12,892 m/s2; P = .04) accumulated player loads and 2-week (62.40 vs 57.25 km; P = .04), 3-week (90.97 vs 84.10 km; P = .03), and 4-week (119.31 vs 111.38 km; P = .05) accumulated total distances were significantly higher for injured players compared with noninjured players during the same time frames. There were no significant differences in player load, total distance, or high-speed distance ACWR between injured and noninjured players for both the rolling averages and EWMA calculations.Conclusion:Higher accumulated player load and total distance, but not ACWR, were associated with injury in women’s soccer players.

Relationship Between Cognitive Performance and Lower Extremity Biomechanics: Implications for Sports-Related Concussion.

Background:Collegiate athletes with prior sports-related concussion (SRC) are at increased risk for lower extremity (LE) injuries; however, the biomechanical and cognitive mechanisms underlying the SRC-LE injury relationship are not well understood.Purpose:To examine the association between cognitive performance and LE land-and-cut biomechanics among collegiate athletes with and without a history of SRC and to determine the association among multiple cognitive testing batteries in the same athlete cohort.Study Design:Controlled laboratory study.Methods:A cohort of 20 collegiate athletes with prior SRC (9 men, 11 women; mean ± standard deviation [SD] age, 20.5 ± 1.3 years; mean ± SD time since last SRC, 461 ± 263 days) and 20 matched controls (9 men, 11 women; mean ± SD age, 19.8 ± 1.3 years) completed land-and-cut tasks using the dominant and nondominant limbs. LE biomechanical variables and a functional visuomotor reaction time (FVMRT) were collected during each trial. Athletes also completed the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT) and Senaptec Sensory Station assessments.Results:In the SRC cohort, Pearson correlation coefficients indicated slower FVMRT was moderately correlated with decreased dominant limb (r = –0.512) and nondominant limb (r = –0.500) knee flexion, while increased dominant limb knee abduction moment was moderately correlated with decreased ImPACT Visual Memory score (r = –0.539) and slower ImPACT Reaction Time (r = 0.515). Most computerized cognitive measures were not associated with FVMRT in either cohort (P > .05).Conclusion:Decreased reaction time and working memory performance were moderately correlated with decreased sagittal plane knee motion and increased frontal plane knee loading in collegiate athletes with a history of SRC. The present findings suggest a potential unique relationship between cognitive performance and LE neuromuscular control in athletes with a history of SRC injury. Last, we determined that computerized measures of cognitive performance often utilized for SRC management are dissimilar to sport-specific cognitive processes.Clinical Relevance:Understanding the relationship between cognitive performance and LE biomechanics in athletes with prior SRC may inform future clinical management strategies. Future research should prospectively assess cognitive and biomechanical measures, along with LE injury incidence, to identify mechanisms underlying the SRC-LE injury relationship.

Relationship between Core Strength, Core Endurance and Balance in Folk Dancers – A Pilot Study

Background: Dance performance requires lower extremity muscle strength and endurance, sufficientcore stabilization, dynamic balance during dance movements. Diminished core strength and coreendurance has been shown lead to a higher incidence of lower extremity injuries and to low backinjuries. Greater core muscle strength, increased core endurance and good dynamic balance havebeen reported to be associated with reduced lower extremity injury risk. Still, the exact relationshipsamong these factors remain unclear. Most of studies have examined ballet and modern dancers but folkdance is not studied adequately in the literature as different genres of dance have different physicaldemands, it is important to examine whether the relationships among Core stability, balance, injuries,and performance are similar across the various dance genres.Objectives: Weak core and poor balance are said to be associated with lower limb and low back injuries.Thus the correlation between core stabilization and balance need to be evaluated in details to reducethe risk of injuries.Methods: It is a cross-sectional observational study, with a total of 30 folk dancers. Core endurancewas measured by using plank tests and core strength was measured by the Bent Knee Lowering Test(BKLT).Balance was measured via the Star Excursion Balance Test (SEBT) which was co-related withcore strength and core endurance.Conclusion: There is no correlation between core strength and balance in folk dancers. Core enduranceis weakly correlated with balance.

Effect of Achilles Tendon Rupture on Player Performance and Longevity in Women's National Basketball Association Players.

Background:Women’s National Basketball Association (WNBA) players have a greater incidence of lower extremity injury compared with male players, yet no data exist on functional outcomes after Achilles tendon rupture (ATR).Purpose:To evaluate the effect of Achilles tendon repair on game utilization, player performance, and career longevity in WNBA athletes.Study Design:Cohort study; Level of evidence, 3.Methods:WNBA players from 1997 to 2019 with a history of ATR (n = 12) were matched 1:2 to a healthy control group. Player characteristics, game utilization, and in-game performance data were collected for each athlete, from which the player efficiency rating (PER) was calculated. Statistical analysis was performed comparing postinjury data to preinjury baseline as well as cumulative career data. Changes at each time point relative to the preinjury baseline were also compared between groups.Results:Of the 12 players with ATR, 10 (83.3%) returned to play at the WNBA level at a mean (±SD) of 12.5 ± 3.3 months. Four players participated in only 1 WNBA season after injury. There were no differences in characteristics between the 10 players who returned to play after injury and the control group. After return to play, the WNBA players demonstrated a significant decrease in game utilization compared with preinjury, playing in 6.0 ± 6.9 fewer games, starting in 12.7 ± 15.4 fewer games, and playing 10.2 ± 9.1 fewer minutes per game (P < .05 for all). After the index date of injury, the players with Achilles repair played 2.1 ± 1.2 more years in the WNBA, while control players played 5.35 ± 3.2 years (P < .01) Additionally, the players with Achilles repair had a significant decrease in PER in the year after injury compared with preinjury (7.1 ± 5.3 vs 11.0 ± 4.4; P = .02). The reduction in game utilization and decrease in PER in these players was maintained when compared with the matched controls (P < .05 for both).Conclusion:The majority of WNBA players who sustained ATR were able to return to sport after their injury; however, their career longevity was shorter than that of healthy controls. There was a significant decrease in game utilization and performance in the year after return to play compared with healthy controls.

Core Strength Training Can Alter Neuromuscular and Biomechanical Risk Factors for Anterior Cruciate Ligament Injury

Background: Core stability is influential in the incidence of lower extremity injuries, including anterior cruciate ligament (ACL) injuries, but the effects of core strength training on the risk for ACL injury remain unclear. Hypothesis: Core muscle strength training increases the knee flexion angle, hamstring to quadriceps (H:Q) coactivation ratio, and vastus medialis to vastus lateralis (VM:VL) muscle activation ratio, as well as decreases the hip adduction, knee valgus, and tibial internal rotation angles. Study Design: Controlled laboratory study. Methods: A total of 48 male participants were recruited and randomly assigned to either the intervention group (n = 32) or the control group (n = 16). Three-dimensional trunk, hip, knee, and ankle kinematic data and muscle activations of selected trunk and lower extremity muscles were obtained while the participants performed side-step cutting. The core endurance scores were measured before and after training. Two-way analyses of variance were conducted for each dependent variable to determine the effects of 10 weeks of core strength training. Results: The trunk endurance scores in the intervention group significantly increased after training (P < .05 for all comparisons). The intervention group showed decreased knee valgus (P = .038) and hip adduction angles (P = .032) but increased trunk flexion angle (P = .018), rectus abdominis to erector spinae coactivation ratio (P = .047), H:Q coactivation ratio (P = .021), and VM:VL activation ratio (P = .016). In addition, the knee valgus angle at initial contact was negatively correlated with the VM:VL activation ratio in the precontact phase (R2 = 0.188; P < .001) but was positively correlated with the hip adduction angle (R2 = 0.120; P < .005). No statistically significant differences were observed in the trunk endurance scores, kinematics, and muscle activations for the control group. Conclusion: Core strength training altered the motor control strategies and joint kinematics for the trunk and the lower extremity by increasing the trunk flexion angle, VM:VL activation ratio, and H:Q activation ratio and reducing the knee valgus and hip adduction angles. Clinical Relevance: Training core muscles can modify the biomechanics associated with ACL injuries in a side-step cutting task; thus, core strength training might be considered in ACL injury prevention programs to alter the lower extremity alignment in the frontal plane and muscle activations during sports-related tasks.

Rearfoot, Midfoot, and Forefoot Motion in Naturally Forefoot and Rearfoot Strike Runners during Treadmill Running

Different location and incidence of lower extremity injuries have been reported in rearfoot strike (RFS) and forefoot strike (FFS) recreational runners. These might be related to functional differences between the two footstrike patterns affecting foot kinematics and thus the incidence of running injuries. The aim of this study was to investigate and compare the kinematic patterns of foot joints between naturally RFS and FFS runners. A validated multi-segment foot model was used to measure 24 foot kinematic variables in long-distance recreational runners while running on a treadmill. These variables included the three-dimensional relative motion between rearfoot, midfoot, and forefoot segments. The footstrike pattern was identified using kinematic data and slow-motion videos. Functional analysis of variance was used to compare the time series of these variables between RFS (n = 49) and FFS (n = 25) runners. In FFS runners, the metatarsal bones were less tilted with respect to the ground, and the metatarsus was less adducted with respect to the calcaneus during stance. In early stance, the calcaneus was more dorsiflexed with respect to the shank and returned to a more plantarflexed position at push-off. FFS runners showed a more adducted calcaneus with respect to the shank and a less inverted midfoot to the calcaneus. The present study has showed that the footstrike angle characterizes foot kinematics in running. These data may help shed more light on the relationship between foot function and running-related injuries.

Impact of foot arch type and minimalist footwear on static postural stability

Intrinsic factors such as foot arch type and extrinsic factors such as footwear are among the main contributors for a higher lower extremity injury incidence due to their impact on postural stability. The purpose of this study was to investigate the impact of foot type and two types of Vibram™ five fingers footwear on static postural stability. Twenty-four healthy males (age 21.38 ± 2.50 years, height 1.74 ± 0.06 m, mass 71.24 ± 10.37 kg) were recruited and categorized into neutral, pronated and supinated categories according to the foot posture index 6. Participants were tested on the barefoot condition first, followed by two types of minimalist Vibram™ footwear [Vibram™ Bikila (VB) and Vibram™ Trek ascent (VT)] in a counterbalanced manner. Static balance was tested on a stable and unstable surface under the following conditions: bilateral eyes open (BL EO), bilateral eyes closed (BL EC), unilateral eyes open (UL EO) and unilateral eyes closed (UL EC)]. The results revealed a significant footwear main effect for the stable BL EO, stable UL EC, and unstable UL EC conditions with greater balance performance in the barefoot condition compared to shod conditions. In the unstable UL EO condition, shod conditions elicited greater balance performance compared to bare feet. Overall, VT had greater balance performance compared to VB. Foot type did not demonstrate a significant impact on static balance. In conclusion, the barefoot condition elicited greater static balance performance in all conditions except during extremely challenging sensory conditions where VT was found to be the footwear of choice, which can be attributed to its design characteristics.

Incidence of Lower Extremity Injury in the National Football League: 2015 to 2018

Background: Lower extremity injuries are the most common injuries in professional sports and carry a high burden to players and teams in the National Football League (NFL). Injury prevention strategies can be refined by a foundational understanding of the occurrence and effect of these injuries on NFL players. Purpose: To determine the incidence of specific lower extremity injuries sustained by NFL players across 4 NFL seasons. Study Design: Descriptive epidemiology study. Methods: This retrospective, observational study included all time-loss lower extremity injuries that occurred during football-related activities during the 2015 through 2018 seasons. Injury data were collected prospectively through a leaguewide electronic health record (EHR) system and linked with NFL game statistics and player participation to calculate injury incidence per season and per 10,000 player-plays for lower extremity injuries overall and for specific injuries. Days lost due to injury were estimated through 2018 for injuries occurring in the 2015 to 2017 seasons. Results: An average of 2006 time-loss lower extremity injuries were reported each season over this 4-year study, representing a 1-season risk of 41% for an NFL player. Incidence was stable from 2015 to 2018, with an estimated total missed time burden each NFL season of approximately 56,700 player-days lost. Most (58.7%) of these injuries occurred during games, with an overall higher rate of injuries observed in preseason compared with regular season (11.5 vs 9.4 injuries per 10,000 player-plays in games). The knee was the most commonly injured lower extremity region (29.3% of lower body injuries), followed by the ankle (22.4%), thigh (17.2%), and foot (9.1%). Hamstring strains were the most common lower extremity injury, followed by lateral ankle sprains, adductor strains, high ankle sprains, and medial collateral ligament tears. Conclusion: Lower extremity injuries affect a high number of NFL players, and the incidence did not decrease over the 4 seasons studied. Prevention and rehabilitation protocols for these injuries should continue to be prioritized.