Running Habits and Injury Frequency Following COVID-19 Restrictions in Adolescent Long-Distance Runners.

PURPOSE: A decline in youth running was observed at the start of the COVID-19 pandemic. We investigated whether the resumption of organized running after social distancing restrictions changed running habits or injury frequency in adolescent runners. METHODS: Adolescents (age = 16.1 [2.1] y) who participated in long-distance running activities completed an online survey in the Spring and Fall of 2020. Participants self-reported average weekly running habits and whether they sustained an injury during the Fall 2020 season. Poisson regression models and 1-way analysis of variance compared running habits while Fisher exact test compared differences in frequencies of injuries during Fall 2020 among season statuses (full, delayed, and canceled). RESULTS: All runners, regardless of season status, increased weekly distance during Fall 2020. Only runners with a full Fall 2020 season ran more times per week and more high-intensity runs per week compared with their Spring 2020 running habits. There were no differences in running volume or running-related injury frequency among Fall 2020 season statuses. CONCLUSIONS: There were no significant differences in running-related injury (RRI) frequency among runners, regardless of season status, following the resumption of cross-country. Health care providers may need to prepare for runners to increase running volume and intensity following the resumption of organized team activities.

Clinical phenotype and musculoskeletal characteristics of patients with aggrecan deficiency.

Aggrecan is a proteoglycan within the physeal and articular cartilage. Aggrecan deficiency, due to heterozygous mutations in the ACAN gene, causes dominantly inherited short stature and, in many patients, early-onset osteoarthritis and degenerative disc disease. We aimed to further characterize this phenotypic spectrum with an emphasis on musculoskeletal health. Twenty-two individuals from nine families were enrolled. Histories and examinations focused on joint health, gait analysis, joint specific patient reported outcomes, and imaging studies were performed. All patients had dominantly inherited short stature, with the exception of a de novo mutation. Short stature was worse in adults versus children (median height -3.05 SD vs. -2.25 SD). ACAN mutations were not always associated with bone age advancement (median advancement +1.1 years, range 0 to +2 years). Children had subtle disproportionality and clinically silent joint disease-25% with osteochondritis dissecans (OD). Adults had a high prevalence of joint symptomatology-decline in knee function, disability from spinal complaints, and lower physical activity on outcome measures. Osteoarthritis (OA) and OD was detected in 90% of adults, and orthopedic surgeries were reported in 60%. Aggrecan deficiency leads to short stature with progressive decline in height SD, mild skeletal dysplasia, and increasing prevalence of joint pathology over time. Optimal musculoskeletal health and quality of life can be attained with timely identification of pathology and intervention.

Sport Specialization and Quality of Life among Middle- and High-School Long-Distance Runners of Different Injury Status: A Retrospective Study.

Running-related injuries are prevalent in adolescent long-distance runners. The aim of our retrospective study was to compare differences in sport specialization, running habits,quality of life, and sleep habits among middle-and high-school long-distance runners of different injury statuses. Middle- and high-school long-distance runners across the United States were recruited via cross-country coaches and athletic directors between January and May 2020. Participants completed an online survey with questions related to demographics, sport specialization, running habits, quality of life, sleep, and self-reported injury history. Overall, 306 participants completed the survey (male = 107, female = 176, unspecified = 23; age = 15.7 ± 1.1 years). Of the participants, 178 (58.2%) reported no history of injury, 101 (33.0%) reported a previous injury, and 27 (8.8%) reported a current injury. Middle- and high-school runners with a current injury reported significantly lower overall health (p= .01) and average distance per run (p = .05) than uninjured runners. No significant differences were found among injury status and sport specialization level, quality of life, sleep habits, or running volume (p> .05). Runners with a self-reported previous or current injury do not appear to be classified as high-specialized runners more frequently than uninjured runners.

Influence of hamstring flexibility on running kinematics in adolescent long-distance runners.

BACKGROUND: Studies have found no or minimal differences in running kinematics between flexible and inflexible adult runners. The interaction between hamstring flexibility and running kinematics has not been reported in adolescent long-distance runners. RESEARCH QUESTION: Does hamstring flexibility influence running kinematics in adolescent long-distance runners? METHODS: Adolescent long-distance runners (n = 140, ages 9-19) were enrolled in our cross-sectional study. Hamstring flexibility was assessed with the forward bending Beighton task. Runners were categorized if they tested positive or negative on the forward bending task. Participants ran at a comfortable self-selected speed on a treadmill. Runners who tested positive on the forward bending task (n = 17) were matched with runners who tested negative on the task (n = 17) according to sex, physical maturation, and running speed. Statistical parametric mapping compared trunk, pelvis, hip, and knee kinematic waveforms throughout the gait cycle and independent sample t tests compared temporal-spatial parameters between the groups. RESULTS: Runners who tested positive on the forward bending task demonstrated significantly greater anterior pelvic tilt during stance (average difference = 4.8° ± 0.4°, p < .001) and swing (average difference = 4.3° ± 0.2°, p < .01) compared to runners who tested negative on the forward bending task. No significant differences were found between groups for the remaining kinematic waveforms or for any temporal-spatial parameters (p > .05). SIGNIFICANCE: This is the first study to report the interaction between hamstring flexibility and running kinematics in adolescent long-distance runners. The greater anterior pelvic tilt demonstrated by runners with greater hamstring flexibility may place more eccentric demands on the hamstring musculature. However, as there were no other differences in joint kinematics or temporal-spatial parameters between groups, greater hamstring flexibility does not appear to have a significant interaction with running kinematics when running at sub-maximal speeds. Our results suggest hamstring flexibility does not predispose adolescent long-distance runners to sub-optimal segment positions associated with running-related injuries.

Cadence in youth long-distance runners is predicted by leg length and running speed.

BACKGROUND: Lower cadence has been previously associated with injury in long-distance runners. Variations in cadence may be related to experience, speed, and anthropometric variables. It is unknown what factors, if any, predict cadence in healthy youth long-distance runners. RESEARCH QUESTION: Are demographic, anthropometric and/or biomechanical variables able to predict cadence in healthy youth long-distance runners. METHODS: A cohort of 138 uninjured youth long-distance runners (M = 62, F = 76; Mean ± SD; age = 13.7 ± 2.7; mass = 47.9 ± 13.6 kg; height = 157.9 ± 14.5 cm; running volume = 19.2 ± 20.6 km/wk; running experience: males = 3.5 ± 2.1 yrs, females = 3.3 ± 2.0 yrs) were recruited for the study. Multiple linear regression (MLR) models were developed for total sample and for each sex independently that only included variables that were significantly correlated to self-selected cadence. A variance inflation factor (VIF) assessed multicollinearity of variables. If VIF≥ 5, variable(s) were removed and the MLR analysis was conducted again. RESULTS: For all models, VIF was > 5 between speed and normalized stride length, therefore we removed normalized stride length from all models. Only leg length and speed were significantly correlated (p < .001) with cadence in the regression models for total sample (R2 = 51.9 %) and females (R2 = 48.2 %). The regression model for all participants was Cadence = -1.251 *Leg Length + 3.665 *Speed + 254.858. The regression model for females was Cadence = -1.190 *Leg Length + 3.705 *Speed + 249.688. For males, leg length, cadence, and running experience were significantly predictive (p < .001) of cadence in the model (R2 = 54.7 %). The regression model for males was Cadence = -1.268 *Leg Length + 3.471 *Speed - 1.087 *Running Experience + 261.378. SIGNIFICANCE: Approximately 50 % of the variance in cadence was explained by the individual's leg length and running speed. Shorter leg lengths and faster running speeds were associated with higher cadence. For males, fewer years of running experience was associated with a higher cadence.

The influence of maturation and sex on pelvis and hip kinematics in youth distance runners.

OBJECTIVES: This study aimed to investigate differences in stance phase pelvic and hip running kinematics based on maturation and sex among healthy youth distance runners. DESIGN: Cross-Sectional. METHODS: 133 uninjured youth distance runners (M = 60, F = 73; age = 13.5 ±â€¯2.7 years) underwent a three-dimensional running analysis on a treadmill at a self-selected speed (2.8 ±â€¯0.6 m·s-1). Participants were stratified as pre-pubertal, mid-pubertal, or post-pubertal according to the modified Pubertal Maturational Observation Scale. Stance phase pelvis and hip range of motion (RoM) and peak joint positions were extracted. Two-way ANCOVAs (sex, maturation; covariate of running velocity) were used with Bonferroni-Holm method to control for multiple comparisons with a target alpha level of 0.05. RESULTS: A two-way interaction between sex and maturation was detected (p = 0.009) for frontal plane pelvic obliquity RoM. Post-hoc analysis identified a maturation main effect only among females (p˂0.008). Pelvic obliquity RoM was significantly greater among post-pubertal (p = 0.001) compared to pre-pubertal females. Significant main effects of sex (p = 0.02), and maturation (p = 0.01) were found for hip adduction RoM. Post-hoc analysis indicated a significant increase in hip adduction RoM from pre-pubertal to post-pubertal female runners (p = 0.001). A significant main effect of sex was found for peak hip adduction angle (p = 0.001) with female runners exhibiting greater maximum peak hip adduction compared to males. CONCLUSIONS: Maturation influences pelvic and hip kinematics greater in female than male runners. Sex differences became more pronounced during later stages of puberty. These differences may correspond to an increased risk for running-related injuries in female runners compared to male runners.

Sport Specialization in Middle School and High School Long-Distance Runners.

CONTEXT: Previous reports suggested that highly specialized adolescent athletes may be at a higher risk of injury, worse sleep quality, and less sport enjoyment than low-level specialized athletes. To date, the sport specialization literature has primarily addressed adolescent athletes in a variety of sports. However, whether the findings on sport specialization in predominantly nonrunning athletes are generalizable to adolescent long-distance runners is unknown. OBJECTIVE: To compare injury history, running volume, quality of life, sleep habits, and running enjoyment among male and female middle school and high school long-distance runners at different sport specialization levels. DESIGN: Cross-sectional study. SETTING: Online survey. PATIENTS OR OTHER PARTICIPANTS: A total of 102 male (age = 15.8 ± 0.9 years) and 156 female (age = 15.6 ± 1.4 years) uninjured middle school and high school athletes who participated in long-distance running activities (completion rate = 50.7%). MAIN OUTCOME MEASURE(S): Participants were stratified by sex and sport specialization level (low, moderate, or high). Group differences were assessed in self-reported running-related injuries, running habits, EQ-5D-Y quality of life, Pittsburgh Sleep Quality Index sleep quality, sleep duration, and running enjoyment. RESULTS: Highly specialized male and female middle school and high school long-distance runners reported more months of competition per year (P < .001), higher weekly run distance (P < .001), more runs per week (P < .001), higher average distance per run (P < .001), and greater running enjoyment (P < .001) than low-level specialized runners. Adolescent boys reported a higher average weekly run distance (P = .01), higher average distance per run (P = .01), and better sleep quality (P = .01) than adolescent girls. No differences among sport specialization levels were found for running-related injuries (P = .25), quality of life (P = .07), sleep quality (P = .19), or sleep duration (P = .11) among male or female middle school and high school runners. CONCLUSIONS: Highly specialized male and female middle school and high school long-distance runners reported higher running volumes and running enjoyment than low-level specialized runners. However, high-level specialized runners did not describe a greater number of running-related injuries, lower quality of life, or lower sleep quality or duration as expected.

Changes in Motivation, Socialization, Wellness and Mental Health in Youth Long-Distance Runners During COVID-19 Social Distancing Restrictions.

Purpose: The COVID-19 pandemic impacted the sporting and exercise activities of millions of youth. Running is an activity that could be maintained while social distancing restrictions were implemented during the pandemic. However, a recent study has indicated that youth runners reported lower running distance, frequency, and intensity during COVID-19. The reason for this reduction and the impact on overall well-being is unknown. Therefore, the purpose of this study was to determine if the social distancing restrictions during the 2020 COVID-19 pandemic influenced running motives, socialization, wellness and mental health in youth long-distance runners. Methods: A customized, open online questionnaire was provided to runners 9-19 years of age who participated in long-distance running activities including team/club cross-country, track and field (distances ≥800 m), road races, or recreational running. Participants responded to questions about demographics, motive for running, and wellness (sleep quality, anxiety, running enjoyment, food consumption quality) 6-months before as well as during social distancing restrictions due to COVID-19. Wilcoxon signed rank tests compared differences for ratio data and Chi-square tests were used to compare proportions before and during COVID-19 social distancing restrictions. Statistical significance was set at p ≤ 0.05. Results: A total of 287 youth long-distance runners (male = 124, female = 162, unspecified = 1; age = 15.3 ± 1.7 years; running experience = 5.0 ± 2.3 years) participated. Compared to their pre-COVID-19 responses, youth long-distance runners reported lower overall motivation to run (p < 0.001) and changes to most motive rankings (p < 0.001 to p = 0.71). The proportion of youth running alone increased during COVID-19 (65.8%) compared to pre-COVID-19 (13.8%, p < 0.001). Youth long-distance runners also reported less running enjoyment (p = 0.001), longer sleep duration (p < 0.001), lower sleep quality (p = 0.05), more anxiety (p = 0.043), and lower food quality consumed (p < 0.001) during COVID-19 social distance restrictions. Conclusion: The COVID-19 social distancing restrictions resulted in significant decreases in motivation and enjoyment of running. The removal of competition and team-based interactions likely had a role in these decreases for this population. Continuing team-based activities (e.g., virtual) during social distancing may help with maintaining motivation of youth long-distance runners. Reduced running occurred concurrently with reduced overall well-being of youth long-distance runners during the COVID-19 pandemic.

Assessment of waveform similarity in youth long-distance runners.

BACKGROUND: Although unimpaired gait is typically assumed to be symmetrical, side-to-side differences in discrete instances of time have been reported in adult and youth runners. These previous results fail to account for the entirety of the motion. RESEARCH QUESTION: Are waveform pattern similarities strong in youth long-distance runners and are the waveform pattern similarities influenced by sex and maturation? METHODS: A cohort of injury-free children and adolescents (n = 103) who participated in long-distance running activities were recruited for the study. Three-dimensional kinematics were collected as participants ran on a treadmill at a self-selected speed. Lower extremity side-to-side waveform symmetries were assessed using the Linear Fit Model. Unpaired t-tests and one-way ANOVA with post-hoc analysis were calculated to determine if sex and/or maturation influenced waveform symmetries. RESULTS: As a whole, waveform similarities were found to be strongest in the sagittal plane and weaker, but still of appropriate strength, in the coronal and transverse planes. Hip rotation and knee varus/valgus measures were found to have the weakest waveform similarities. High waveform similarity variability was measured within the cohort, particularly in the coronal and transverse planes. Waveform similarities were not found to be influenced by either sex or maturation. SIGNIFICANCE: While the group as a whole demonstrated strong waveform similarities, some level of asymmetry in a population of uninjured, long-distance youth runners is normal as none of the measures demonstrated perfect symmetry. Prospective study is warranted to identify thresholds of waveform similarity and to determine if these findings can be used to predict running performance and injury risk.

ALTERED SAGITTAL PLANE HIP BIOMECHANICS IN ADOLESCENT MALE DISTANCE RUNNERS WITH A HISTORY OF LOWER EXTREMITY INJURY.

BACKGROUND: Lower extremity overuse injuries, including bone stress injuries (BSI), are common in runners and may result in prolonged recovery and time off from running. Identifying risk factors for running-related overuse injuries may have a clinically relevant role in prevention of these injuries. PURPOSE: The purpose of this study was to compare an adolescent and young adult population of male runners known to have a history of BSI with an injury-free cohort and retrospectively assess for kinematic differences that may differentiate the two cohorts. STUDY DESIGN: Controlled laboratory case control investigation. LEVEL OF EVIDENCE: Level 3. METHODS: 25 male high school and collegiate cross-country runners were enrolled. Ten self-reported a prior history of BSI consisting of lower extremity stress fracture or shin splints/medial tibial stress syndrome and were categorized as injured (INJ). Fifteen self-reported no prior history of lower extremity injury and were categorized as uninjured (UNINJ). All runners were pain-free at time of testing. Runners ran at a self-selected speed on a treadmill with retro-reflective markers attached to thorax, pelvis, and each lower extremity segment. Three-dimensional kinematic calculations were made during stance phase (initial treadmill heel contact to toe off) and averaged over 20 steps. One-way ANCOVA was used to compare kinematic differences at the hip and knee between the INJ and UNINJ cohort. RESULTS: Runners in the INJ group demonstrated greater peak hip flexion during stance phase on both the right limb [INJ = 32.5°(±3.8°) vs. UNINJ = 26.9°(±4.6°); p<0.01] and the left limb [INJ = 31.2°(±4.8°) vs. UNINJ = 26.8°(±3.1°); p = 0.01] when compared to the UNINJ group. No significant difference in step length or step rate between the INJ and UNINJ cohorts was noted when normalized to height and weight (p = 0.39 and 0.39). CONCLUSIONS: The results of this study demonstrate increased peak stance phase hip flexion in a population of young adult male runners with a previous history of BSI. This association may represent an important preliminary finding in the development of a clinically relevant tool to identify risk of BSI. Due to the retrospective nature of this study, future prospective investigations are warranted to validate these findings to determine if these alterations are compensatory following an injury or predictive of a future injury.

Concurrent validity and reliability of 2d kinematic analysis of frontal plane motion during running.

PURPOSE: Three-dimensional motion analysis is the "gold standard" for evaluating kinematic variables during treadmill running. However, its use is limited by temporal and financial restraints. Therefore, the purpose of this study was to assess the concurrent validity and reliability of 2D video analysis for frontal plane kinematic variables during treadmill running. METHODS: Twenty-four healthy male and female collegiate cross-country runners completed a running protocol at a self-selected speed. Frontal plane kinematic data were collected using 3D and 2D motion analysis systems. Variables of interest included contralateral pelvic drop (CPD), peak hip adduction angle (HADD), and peak knee abduction angle (KABD). Pearson Product Correlation Coefficients were used to determine the relationship between the 3D and 2D systems for each variable. Intra-Class Correlation Coefficients (ICC) were used to assess intra-rater reliability of the user of the 2D software. RESULTS: The 2D testing method demonstrated excellent intra-rater reliability for peak HADD (ICCs: 0.951-0.963), peak CPD (0.958-0.966), and peak KABD (ICCs: 0.955-0.976). Moderate correlations between 2D and 3D measures of HADD on the left (0.539; p=0.007) and the right (0.623; p=0.001) and peak KABD on the left (0.541; p=.006) lower extremity were found. No statistically significant correlation of CPD was found between the 2D and 3D systems. The 2D measure of CPD had a strong correlation to the 2D assessment of HADD on both the left (0.801; p=0.0001) and the right (0.746; p=0.0001) extremity. CONCLUSION: These findings and the ease of data capture using 2D software provide support for the utility of 2D video analysis in the evaluation of frontal plane variables, specifically HADD. LEVEL OF EVIDENCE: 2B.

Reduced hip strength is associated with increased hip motion during running in young adult and adolescent male long-distance runners.

STUDY DESIGN: Controlled laboratory study. BACKGROUND AND PURPOSE: Anterior knee pain is one of the most common running symptoms reported in the literature. While the exact etiology is unknown, a lack of hip strength is suggested to contribute to abnormal running mechanics. The purpose of this research study was to evaluate the association between isokinetic hip strength and 3-D running kinematics. METHODS: 33 male high school and collegiate cross country runners participated in this study. Peak isokinetic hip abductor and hip extensor strength were assessed. Each subject also completed a treadmill running protocol at a self-selected speed (mean = 3.8 m/s). 3-D kinematic data were collected at 240 Hz using a 10-camera motion capture system. Pearson correlation coefficients were used to determine the relationship between hip strength and hip range of motion (ROM) during the stance phase of running (p<0.05). RESULTS: Peak isokinetic hip extensor torque was inversely correlated with transverse plane hip ROM (r = -.387, p = .026) but was not significantly related to sagittal plane hip ROM or frontal plane hip ROM. Peak isokinetic hip abductor torque was inversely correlated with frontal plane hip ROM (r=-.462, p=.008) but was not significantly related to either sagittal plane hip ROM or transverse plane hip ROM. Peak isokinetic hip extensor torque and peak isokinetic hip abductor torque were not significantly related to knee kinematics in any plane. CONCLUSIONS: Peak isokinetic hip extensor torque and peak isokinetic hip abductor torque are associated with transverse plane and frontal plane hip kinematics, but not knee kinematics. LEVELS OF EVIDENCE: Level 3b.

Relationship between hip strength and trunk motion in college cross-country runners.

PURPOSE: Hip strength may directly relate to abnormal running mechanics and contribute to the high incidence of overuse injuries in distance runners. The purpose of this study was to determine the relationship between hip isokinetic strength and thorax and pelvic motion during treadmill running. METHODS: Isokinetic hip strength and treadmill running kinematics were collected on 24 collegiate cross-country runners (14 males and 10 females). Each subject completed a running protocol on a treadmill at a self-selected speed (3.58 ± 0.26 m·s) and prescribed speed (3.58 ± 0.0 m·s). Kinematic data were collected with retroreflective markers attached to the thorax, pelvis, and each lower extremity segment (thigh, shank, and foot). Thorax and pelvis range of motion (ROM) were calculated from initial ground contact to toe-off. Pearson correlation coefficients were used to determine the relationship between strength and ROM (P < 0.05). Differences between male and female athletes were tested with mixed-design ANOVAs (P < 0.05). RESULTS: Isokinetic hip extension and abduction torque had significant inverse correlations to thorax axial rotation ROM during stance phase of running (r = -0.60 and r = -0.53) at self-selected speed. Frontal plane pelvic obliquity ROM was also significantly correlated to hip strength (extension r = -0.49; abduction r = -0.44). Similar correlations were found during the prescribed speed condition. Female runners had significantly decreased normalized strength (hip extension 1.8 ± 0.4 N·m·kg, P < 0.05; hip abduction 1.0 ± 0.2 N·m·kg, P < 0.05), increased pelvic obliquity (13.1° ± 2.6°, P < 0.05), and thorax axial rotation (34.5° ± 7.0°, P < 0.05) ROM compared to males (hip extension 2.5 ± 0.5 N·m·kg; hip abduction 1.3 ± 0.2 N·m·kg; pelvic obliquity 8.9° ± 1.9°; thorax axial rotation 22.6° ± 3.5°). CONCLUSIONS: Moderate correlations were found in hip extensor and hip abductor strength and pelvic and thorax motion during running in collegiate runners.

Prevention of overuse sports injuries in the young athlete.

The purpose of this article is to review the current theories regarding prevalence, mechanism, and prevention strategies for overuse injuries in a young athletic population. This information provides valuable insight into the state of the current evidence regarding overuse injuries in young athletes as well as the potential future directions in the development of overuse injury prevention interventions.

Femoral neck stress fracture and femoroacetabular impingement.

The patient was a 34-year-old male recreational marathon runner referred to a physical therapist with a chief complaint of worsening right lateral hip pain of 3 months duration that was insidious in nature. Following a physical examination, the physical therapist discussed his suspicions with the referring physician. Magnetic resonance imaging revealed findings consistent with a stress fracture at the inferomedial right femoral neck, a mild cam-type deformity of the right femoral neck, and a mild degree of heterogeneity of the right superior anterior labrum, representing a possible tear.