Epidemiology of National Collegiate Athletic Association Men's and Women's Cross-Country Injuries, 2009-2010 Through 2013-2014

An Investigation Into the Measurement of Injury Severity in Running-Related Injury Research: A Scoping Review

Understanding injury severity is essential to inform injury prevention practice. The aims of this scoping review were to investigate how running-related injury (RRI) severity is measured, compare how it differs across studies, and examine whether it influences study outcomes (i.e., injury rates and risk factor identification). This scoping review was prospectively registered with Open Science Framework. A systematic electronic search was conducted using PubMed, Scopus, SPORTDiscuss, MEDLINE, and Web of Science databases. Included studies were published in English between January 1980 and December 2023, investigated RRIs in adult running populations, and included a measure of injury severity. Results were extracted and collated. Sixty-six studies were included. Two predominant primary criteria are used to define injury severity: the extent of the effect on running and/or the extent of the physical description. When secondary definition criteria are considered, 13 variations of injury severity measurement are used. Two approaches are used to grade injury severity: a categorization approach or a continuous numerical scale. Overall, the measurement of RRI severity is relatively inconsistent across studies. Less than half of studies report incidence rates per level of injury severity, while none report specific risk factors across levels, making it difficult to determine if the approach to measuring injury severity influences these study outcomes. This lack of information is possibly contributing to inconsistent rates of RRIs reported, and the lack of clarity on risk factors.

Do we underestimate the frequency of ankle sprains in running? A systematic review and meta-analysis

OBJECTIVE

To provide a systematic review and meta-analysis of the proportion of ankle sprains in running practices.

DESIGN

Systematic review and meta-analysis.

MAIN OUTCOME MEASURES

We calculated the weighted summary proportion and conducted meta-analyses for runners, considering levels (elite/recreational) and disciplines (distance, track, cross-country, trail, and orienteering).

RESULTS

32 studies were included in the systematic review and 19 were included in the meta-analysis with a level of quality ranging from poor to good. Proportion of ankle sprains in runners was 13.69% (95%CI = 7.40-21.54; I2 = 98.58%) in global, 12.20% (95%CI = 5.24-21.53; I2 = 89.31%) in elite, 19.40% (95%CI = 10.05-30.90; I2 = 99.09%) in recreational, 8.51% (95%CI = 4.22-14.12; I2 = 96.15%) in distance, 67.42% (95%CI = 0.50-82.85; I2 = 99.36%) in track, 27.07% (95%CI = 12.48-44.81; I2 = 97.97%) in cross-country, and 25.70% (95%CI = 19.87-32.14; I2 = 0.00) in orienteering.

CONCLUSIONS

Running practice results in significant proportion rate of ankle sprains. Recreational runners exhibit higher proportion than elite. Running disciplines, especially track, cross-country, and orienteering, influence reported ankle sprain rates, surpassing those of distance runners.

Differences in Injury Profiles Between Female and Male Athletes Across the Participant Classification Framework: A Systematic Review and Meta-Analysis

BACKGROUND

Female sex is a significant determinant of anterior cruciate ligament (ACL) injury. It is not understood if sex is a key determinant of other sports-related injuries.

OBJECTIVE

The aim of this systematic review was to identify where differences in injury profiles are most apparent between the sexes in all sports across the six-tiered participant classification framework.

METHODS

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and the 'implementing PRISMA in Exercise, Rehabilitation, Sport medicine and SporTs science'(PERSiST) guidance. The databases PubMed, CINAHL, Web of Science, SPORTDiscus, Medline, Scopus, Cochrane Library and EBSCO were searched from database inception to 24 April 2023. Longitudinal, prospective and retrospective cohort studies and cross-sectional and descriptive epidemiology studies that used standard injury data collection were included. Studies were excluded if injuries were not medically diagnosed and if injuries were not reported and/or analysed by sex. Two reviewers independently extracted data and assessed study quality using the Downs and Black checklist.

RESULTS

Overall, 180 studies were included (8 tier-5, 40 tier-4, 98 tier-3, 30 tier-2, 5 tier-1 studies; one study included data in two tiers). Of those, 174 studies were of moderate quality and six studies were of limited quality. In sex-comparable sports, there was moderate evidence that female athletes had greater risk of knee injury (relative risk (RR) 2.7; 95% CI 1.4-5.5), foot/ankle injuries (RR 1.25; 95% CI 1.17-1.34), bone stress injury (RR 3.4; 95% CI 2.1-5.4) and concussion (RR 8.46; 95% CI 1.04-68.77) than male athletes. Male athletes were at increased risk of hip/groin injuries (RR 2.26; 95% CI 1.31-3.88) and hamstring injuries (RR 2.4; 95% CI 1.8-3.2) compared with females, particularly in dynamic sports. Male athletes were 1.8 (1.37-2.7) to 2.8 (2.45-3.24) times more likely to sustain acute fractures than female athletes, with the highest risk in competition.

DISCUSSION

Most studies in all cohorts were of moderate quality (mean/range of scores tier-5: 17 ± 2.2 [14-20], tier-4: 16.9 ± 1.9 [11-21], tier-3: 16.9 ± 1.5 [11-20], tier-2: 16.3 ± 2.2 [11-20], tier-1 studies: 15.6 ± 1.3 [14-17] out of 28 on the Downs and Black checklist), with only six studies of limited quality. Female athletes' propensity for bone stress injuries highlights opportunities to reinforce development of optimal bone health during adolescence and to outline the effects of energy availability. Earlier strength development and exposure to neuromuscular training programmes and modification of skill development in female athletes may be effective strategies for reducing lower limb injury risk. Key components of neuromuscular training programmes could be beneficial for reducing hip/groin and hamstring injury risk in male athletes. There may be a need for sex-specific prevention and return-to-sport protocols for sports-related concussion in female athletes.

CONCLUSIONS

Female sex was a key determinant of sports-related injuries beyond ACL injury including foot/ankle injury, bone stress injury and sports-related concussion. Male sex was a key determinant of hip/groin, hamstring injury and upper limb injury.

TRIAL REGISTRY

PROSPERO registration number: CRD42017058806 (last updated on 7th June 2023).

Transference of outdoor gait-training to treadmill running biomechanics and strength measures: A randomized controlled trial

Outdoor gait-training has been successful in improving pain and reducing contact time during outdoor running for runners with exercise-related lower leg pain (ERLLP). However, it is unclear if these adaptations translate to gold standard treadmill running and clinical strength assessments. The study purpose was to assess the influence of a 4-week outdoor gait-training intervention with home exercises (FBHE) on treadmill running biomechanics and lower extremity strength compared to home exercises alone (HE) among runners with ERLLP. Seventeen runners with ERLLP were randomly allocated to FBHE and HE groups (FBHE: 3 M, 6F, 23 ± 4 years, 22.0 ± 4.6 kg/m2; HE: 3 M, 5F, 25 ± 5 years, 24.0 ± 4.0 kg/m2). Both groups completed eight sessions of home exercises over 4 weeks. The FBHE group received gait-training through wearable sensors to reduce contact time. Treadmill running gait and clinical strength assessments were conducted at baseline and 4-weeks. Multivariate repeated measures analyses of variance were used to assess the influence of group and timepoint for all outcomes. The FBHE group demonstrated significantly decreased contact time at 4-weeks compared to baseline and the HE group (Mean Difference [MD] range: -42 ms - -39 ms; p-range: <0.001-0.02). The FBHE group had significantly increased cadence (MD: +21 steps/min; p = 0.003) and decreased loading impulse (MD: -51, p < 0.001) during treadmill running at 4-weeks compared to the HE group. Strength did not significantly differ adjusting for multiple comparisons (p > 0.007). The outdoor FBHE intervention transferred to favorable changes in treadmill running biomechanics. Clinicians treating runners with ERLLP patients should implement data-driven outdoor gait-training to maximize patient benefits across running locations.

Preinjury Knee and Ankle Mechanics during Running Are Reduced among Collegiate Runners Who Develop Achilles Tendinopathy

INTRODUCTION

Achilles tendinopathies (AT) are common in runners, but prospective data assessing running mechanics associated with developing AT are limited. Asymmetry in running mechanics is also considered a risk factor for injury, although it is unknown if the problematic mechanics occur on the injured limb only or are present bilaterally.

PURPOSE

This study aimed to prospectively identify differences in preinjury running biomechanics in collegiate runners who did and did not develop AT and determine if between-limb asymmetries were associated with which limb developed AT.

METHODS

Running gait data were obtained preseason on healthy collegiate cross-country runners, and AT incidence was prospectively recorded each year. Spatiotemporal, ground reaction forces, and joint kinematics and kinetics were analyzed. Linear mixed-effects models assessed differences in biomechanics between those who did and did not develop AT during the subsequent year. Generalized linear mixed-effects models determined if the asymmetry direction was associated with which limb developed an AT, with odds ratios (OR) and 95% confidence intervals (95% CI) reported.

RESULTS

Data from 106 runners were analyzed and 15 developed AT. Preinjury biomechanics of runners who developed AT showed less peak knee flexion (noninjured: 45.9° (45.2°-46.6°), injured: 43.2° (41.5°-44.9°), P < 0.001), ankle dorsiflexion (noninjured: 28.7° (28.0°-30.2°), injured: 26.0° (23.8°-28.3°), P = 0.01), and knee extensor moment (noninjured: -2.18 (N·m)·kg -1 (-2.24 to -2.12 (N·m)·kg -1 ), injured: -2.00 (N·m)·kg -1 (-2.17 to -1.84 (N·m)·kg -1 ), P = 0.02). The limb demonstrating less peak knee flexion had greater odds of sustaining an AT (OR, 1.29 (1.00-1.65), P = 0.05).

CONCLUSIONS

Knee and ankle kinematics, in addition to knee kinetics, were associated with developing an AT. Monitoring these mechanics may be useful for prospectively identifying runners at risk of developing AT.

Adolescent and young adult hip and knee strength profiles relate to running gait biomechanics

OBJECTIVES

Compare and assess relationships between strength and running biomechanics among healthy adolescents and young adult males and females.

DESIGN

Retrospective cohort.

SETTING

Clinic.

PARTICIPANTS

802 healthy participants (570 F, 232 M; 16.6 ± 2.3 years).

MAIN OUTCOME MEASURES

Mass-normalized knee flexor and extensor strength, hip adductor and abductor strength, hamstrings-to-quadriceps (H:Q), and abductor-to-adductor (Abd:Add) ratios were obtained using hand-held dynamometry. Mass-normalized peak vertical ground reaction force (vGRF), %stance, cadence, and stride length were obtained using an instrumented treadmill. Multivariate analyses of variance were used to compare strength and biomechanics across ages and sexes. Linear regressions were used to assess the relationships between strength and biomechanics, accounting for speed, age, and sex. Independent t-tests were used to compare strength between strength ratio profiles.

RESULTS

Strength and running biomechanics significantly differed between sexes (p-range: <0.001-0.05) and age groups (p-range: <0.001-0.02). Strength and strength ratios were significantly associated with increased cadence (p-range:0.001-0.04) and stride lengths (p-range:0.004-0.03), and decreased vGRF (p < 0.001). Lower H:Q ratios had significantly lower strength measures (p < 0.001). Higher Abd:Add ratios had significantly increased abductor strength (p < 0.001).

CONCLUSIONS

Strength and running biomechanics differed by sexes and ages. Hip and knee strength and strength ratios were related to select spatiotemporal and kinetic biomechanical features.

A hierarchical clustering approach for examining the relationship between pelvis-proximal femur geometry and bone stress injury in runners

Bone stress injury (BSI) risk in runners is multifactorial and not well understood. Unsupervised machine learning approaches can potentially elucidate risk factors for BSI by identifying groups of similar runners within a population which differ in BSI incidence. Here, a hierarchical clustering approach is used to identify groups of collegiate cross country runners based on 2-dimensional frontal plane pelvis and proximal femur geometry, which was extracted from dual-energy X-ray absorptiometry scans and dimensionally reduced by principal component analysis. Seven distinct groups were identified using the cluster tree, with the initial split being highly related to female-male differences. Visual inspection revealed clear differences between groups in pelvis and proximal femur geometry, and groups were found to differ in lower body BSI incidence during the subsequent academic year (Rand index = 0.53; adjusted Rand index = 0.07). Linear models showed between-cluster differences in visually identified geometric measures. Geometric measures were aggregated into a pelvis shape factor based on trends with BSI incidence, and the resulting shape factor was significantly different between clusters (p < 0.001). Lower shape factor values, corresponding with lower pelvis height and ischial span, and greater iliac span and trochanteric span, appeared to be related to increased BSI incidence. This trend was dominated by the effect observed across clusters of male runners, indicating that geometric effects may be more relevant to BSI risk in males, or that other factors masked the relationship in females. More broadly, this work outlines a methodological approach for distilling complex geometric differences into simple metrics that relate to injury risk.

Changes in the incidence of stress reactions and fractures among intercollegiate athletes after the COVID-19 pandemic

PURPOSE

The purpose of this study was to characterize the impact of detraining due to the COVID-19 pandemic on incidence of bony injuries and stress fractures in collegiate athletes.

METHODS

A comprehensive collegiate athletic conference injury database was queried for all in-season, sport-related bony injuries (defined as all stress reactions and fractures) that occurred across all sports from January 2016 to June 2021. The bony injury rate per 1000 athlete exposure hours (AEH) was calculated and compared between the immediate post-hiatus season and historic rates from pre-hiatus seasons (2016-2019). Injury characteristics were also compared between the pre- and post-hiatus time periods.

RESULTS

A total of 868 bony injuries across 23 sports were identified. The sports with highest overall baseline bony injury rates in historic seasons were women's cross country (0.57 injuries per 1000 AEH) and men's cross country (0.32). Compared to historic pre-hiatus rates, female cross-country runners demonstrated a significantly lower bony injury incidence rate in the post-hiatus season (0.24 vs. 0.57, p = 0.016) while male swimming athletes demonstrated a statistically significant increase in bony injury rate (0.09 vs. 0.01, p = 0.015). The proportion of bony injuries attributed to repetitive trauma increased; while, the proportion of injuries attributed to running decreased between the pre- and post-hiatus seasons.

CONCLUSION

Across all sports, there was no consistent trend toward increased rates of bony injury in the immediate post-hiatus season. However, female cross-country runners demonstrated lower rates of bony injury in the post-hiatus season while male swimmers demonstrated higher rates. Furthermore, bony injuries in the post-hiatus season were more likely to be the result of repetitive trauma and less likely to be from running.

LEVEL OF EVIDENCE

Level III, retrospective, cross sectional study.

Untangling risk factors including discipline-specific exposure for injuries in preprofessional and professional circus artists in the USA

Objective

This prospective cohort study quantified injury patterns related to specific circus discipline exposure in preprofessional and professional circus artists.

Methods

Circus artists (n=201; ages 13-69; 172 female, 29 male assigned sex at birth) were enrolled in 10 cities across the USA. Participants were followed for 1 year from enrolment, completing a weekly training log and undergoing a physical therapist evaluation for injuries. The circus-specific extension of the International Olympic Committee 2020 consensus on recording injury and illness in sports was used to analyse injury patterns.

Results

The study completion rate was 77% (n=155). Data were analysed by participant subgroup (age, professional status, sex at birth). The highest injury rates in participant subgroups were for males (5.69/1000 exposures) and related to discipline subgroups, were in aerial with ground elements (5.93/1000 exposures) and aerial (4.26/1000 exposures). Adults had more injuries related to aerial, whereas adolescents had more related to ground disciplines (χ² (2)=10.62, p=0.005) and non-time loss injuries (χ² (1)=5.45, p=0.02). Females had a higher proportion of repetitive injuries (70% vs 55%) than males (χ² (1) = 4.43, p=0.035). Individuals with an eating disorder history had more (p<0.004) injuries (mean 2.27±2.29) than those without (mean=1.48±0.96).

Conclusions

This study showed that intrinsic factors (age, sex at birth and history of eating disorder) and extrinsic factors (circus discipline exposure) affect injury risk. We need to account for the intersectionality of these factors to address risk management at an individual and group level.

Kinetic and Spatiotemporal Characteristics of Running During Regular Training Sessions for Collegiate Male Distance Runners Using Shoe-Based Wearable Sensors

CONTEXT

Assessment of running mechanics has traditionally been conducted in laboratory settings; the advancement of wearable technology permits data collection during outdoor training sessions. Exploring changes in running mechanics across training-session types may assist runners, coaches, and sports medicine clinicians in improving performance and managing the injury risk.

OBJECTIVE

To examine changes in running mechanics on the basis of routine training-session types.

DESIGN

Descriptive observational study.

SETTING

Field based, university.

METHODS

Running mechanics data (ie, impact g, stride length, braking g, total shock g, cadence, and ground contact time) for National Collegiate Athletic Association Division I distance runners (n = 20 men) were collected using RunScribe sensors mounted to the laces during training sessions (long run [LR], interval run [IR], or recovery run [RR]) during a 1-week period.

RESULTS

Repeated-measures analysis of covariance with Greenhouse-Geisser correction and training-session pace as a covariate indicated no statistically significant differences in spatiotemporal or kinetic measures across the 3 training-session types. Cadence and stride length were inversely related in all training sessions (LR: r = -0.673, P = .004; IR: r = -0.893, P < .001; RR: r = -0.549, P = .023). Strong positive correlations were seen between impact g and total shock in all training sessions (LR: r = 0.894, P < .001; IR: r = 0.782, P = < .001; RR: r = 0.922, P < .001). Ground contact time increased with stride length during LR training sessions (r = 0.551, P = .027) and decreased with braking g in IR training sessions (r = -0.574, P = .016) and cadence in RR training sessions (r = -0.487, P = .048).

CONCLUSIONS

Running mechanics in collegiate distance runners were not statistically different among training-session types when training-session pace was controlled. The use of wearable technology provides a tool for obtaining necessary data during overland training to inform training and program design.

Sex-related differences in hip and groin injuries in adult runners: a systematic review

OBJECTIVES

Hip/groin running-related injuries (RRIs) are relatively uncommon. It is unclear if runners of either sex are disproportionately affected. Our objective was to systematically review differences in hip/groin RRIs between males and females.

DATA SOURCES

A structured and comprehensive search of four medical literature databases was performed (PubMed, Embase, Ovid Medline, and CINAHL). Terms searched were as follows: risk, epidemiology, hip injury, groin injury, overuse injury, running, sprinting, and track and field.

STUDY SELECTION

Studies reporting sex-specific data on hip/groin RRIs in adult runners were included. Data was extracted and reviewed independently by two authors.

STUDY APPRAISAL AND DATA SYNTHESIS

Sex-specific injury rates, risk factors, and return to sport (RTS) following hip/groin RRI were extracted. Risk of bias was assessed using the Joanna-Briggs Institute Critical Appraisal Tool.

RESULTS

Ten studies with 7,353 total runners were included: 2,315 (47%) males and 2,559 (53%) females. The mean age of the included runners was 37.3 ± 8.9 years and the mean weekly running distance was 10.4 ± 8.4 km. Hip/groin injuries comprised 10.1% (491/4,874) of total RRIs, including 6.3% of RRIs sustained by males and 11.0% by females. Three studies reported significantly higher rates of hip/groin RRIs in female runners. One study reported significantly higher rates of gluteus medius and adductor RRIs for females and males, respectively. One study identified female sex as an independent risk factor for hip/groin RRIs. Three studies reported on RTS after hip/groin RRIs: the pooled RTS rate was 81.4% (57/70) at 1 to 368 days after injury.

LIMITATIONS

Data was pooled when possible; however, there was considerable clinical, methodological, and statistical heterogeneity across studies.

CONCLUSIONS

Hip/groin RRIs comprise a greater percentage of total injuries among injured female runners relative to males. Females may be at a higher risk for sustaining hip/groin RRIs though more research on risk factors and RTS is needed.

Gait asymmetry and running-related injury in female collegiate cross-country runners

BACKGROUND

Running biomechanics are commonly linked to injury. There is limited evidence on the effects of running speed on asymmetry and the prospective association of asymmetry and injury. The purposes of this study were to describe the degree in asymmetry in biomechanical variables commonly associated with injury, examine the effect of speed on asymmetry, and determine if there were any significant differences in pre-season measures of asymmetry between runners who went on to sustain an injury during the competitive season compared to those who remained healthy.

METHODS

Three-dimensional running biomechanics were obtained from twenty-two female collegiate cross-country runners at four different running speeds prior to their season. Asymmetry was quantified using the Symmetry Angle. Participants were followed over the twelve-week season and all time-loss injuries were identified.

FINDINGS

There was no significant effect of velocity on asymmetry. Additionally, there were no significant differences in symmetry between runners who sustained an injury (n = 7) and those that remained injury-free (n = 15) during the cross-country season.

INTERPRETATION

Clinicians working with runners should expect a high degree of symmetry in running biomechanics when performing gait analyses across running speeds. In regards to injury, caution should be used when linking injury to asymmetry.

Relationships between Running Biomechanics, Hip Muscle Strength, and Running-Related Injury in Female Collegiate Cross-country Runners

Background

Female collegiate cross-country (XC) runners have a high incidence of running-related injury (RRI). Limited reports are available that have examined potential intrinsic factors that may increase RRI risk in this population.

Purpose

To examine the relationships between RRI, hip muscle strength, and lower extremity running kinematics in female collegiate XC runners.

Study Design

Prospective observational cohort.

Methods

Participants included twenty female NCAA collegiate XC runners from Southern California universities who competed in the 2019-20 intercollegiate season. A pre-season questionnaire was used to gather demographic information. Hip muscle strength was measured with isokinetic dynamometry in a sidelying open-chain position and normalized by the runner's body weight (kg). Running kinematic variables were examined using Qualisys 3D Motion Capture and Visual 3D analysis. RRI occurrence was obtained via post-season questionnaires. Independent t-tests were used to determine mean differences between injured and non-injured runners for hip abductor muscle strength and selected running kinematics. Pearson correlation coefficients were calculated to examine relationships between hip muscle performance and kinematic variables.

Results

End-of-the-season RRI information was gathered from 19 of the 20 participants. During the 2019-20 XC season, 57.9% (11 of 19) of the runners sustained an RRI. There were no significant differences between mean hip abductor normalized muscle strength (p=0.76) or mean normalized hip muscle strength asymmetry (p=0.18) of injured and non-injured runners during the XC season. Similarly, no significant differences were found between mean values of selected kinematic variables of runners who did and who did not report an RRI. Moderate relationships were found between hip abductor strength variables and right knee adduction at footstrike (r=0.50), maximum right knee adduction during stance (r=0.55), left supination at footstrike (r=0.48), right peak pronation during stance (r=-0.47), left supination at footstrike (r=0.51), and right peak pronation during stance (r=-0.54) (all p≤0.05).

Conclusions

Hip abduction muscle strength, hip abduction strength asymmetry, and selected running kinematic variables were not associated with elevated risk of RRI in female collegiate XC runners.

Level of Evidence

Influence of exercise intensity and hypoxic exposure on physiological, perceptual and biomechanical responses to treadmill running

AbstractAcute physiological, perceptual and biomechanical consequences of manipulating both exercise intensity and hypoxic exposure during treadmill running were determined. On separate days, eleven trained individuals ran for 45 s (separated by 135 s of rest) on an instrumented treadmill at seven running speeds (8, 10, 12, 14, 16, 18 and 20 km.h^-1) in normoxia (NM, FiO₂ = 20.9%), moderate hypoxia (MH, FiO₂ = 16.1%), high hypoxia (HH, FiO₂ = 14.1%) and severe hypoxia (SH, FiO₂ = 13.0%). Running mechanics were collected over 20 consecutive steps (i.e., after running ∼25 s), with concurrent assessment of physiological (heart rate and arterial oxygen saturation) and perceptual (overall perceived discomfort, difficulty breathing and leg discomfort) responses. Two-way repeated-measures ANOVA (seven speeds × four conditions) were used. There was a speed × condition interaction for heart rate (p = 0.045, ηp²=0.22), with lower values in NM, MH and HH compared to SH at 8 km.h^-1 (125 ± 12, 125 ± 11, 128 ± 12 vs 132 ± 10 b.min^-1). Overall perceived discomfort (8 and 16 km.h^-1; p = 0.019 and p = 0.007, ηp² =0.21, respectively) and perceived difficulty breathing (all speeds; p = 0.023, ηp² =0.37) were greater in SH compared to MH, whereas leg discomfort was not influenced by hypoxic exposure. Minimal difference was observed in the twelve kinetics/kinematics variables with hypoxia (p > 0.122; η_p²= 0.19). Running at slower speeds in combination with severe hypoxia elevates physiological and perceptual responses without a corresponding increase in ground reaction forces.

A hierarchical clustering approach for examining potential risk factors for bone stress injury in runners

Bone stress injuries (BSI) are overuse injuries that commonly occur in runners. BSI risk is multifactorial and not well understood. Unsupervised machine learning approaches can potentially elucidate risk factors for BSI by looking for groups of similar runners within a population that differ in BSI incidence. Here, a hierarchical clustering approach is used to identify groups of collegiate cross country runners (32 females, 21 males) based on healthy pre-season running (4.47 m·s^-1) gait data which were aggregated and dimensionally reduced by principal component analysis. Five distinct groups were identified using the cluster tree. Visual inspection revealed clear differences between groups in kinematics and kinetics, and linear mixed effects models showed between-group differences in metrics potentially related to BSI risk. The groups also differed in BSI incidence during the subsequent academic year (Rand index = 0.49; adjusted Rand index = -0.02). Groups ranged from those including runners spending less time contacting the ground and generating higher peak ground reaction forces and joint moments to those including runners spending more time on the ground with lower loads. The former groups showed higher BSI incidence, indicating that short stance phases and high peak loads may be risk factors for BSI. Since ground contact duration may itself account for differences in peak loading metrics, we hypothesize that the percentage of time a runner is in contact with the ground may be a useful metric to include in machine learning models for predicting BSI risk.

The Problem of Recurrent Injuries in Collegiate Track and Field

Background

As with most sports, participating in Track and Field (T&F) has inherent injury risks and a previous injury often predisposes athletes to a greater future injury risk. However, the frequency and burden of recurrent injuries in collegiate T&F have not been closely examined.

Purpose

The purpose of this study was to describe the frequency and burden of recurrent injuries in collegiate T&F and compare differences in the time loss associated with initial and recurrent injuries by sex and T&F discipline.

Study Design

Descriptive Epidemiology Study.

Methods

Data from the NCAA Injury Surveillance Program were analyzed to describe the frequency and burden of recurrent injuries in collegiate T&F between 2009 and 2014. Comparisons of recurrent injury proportions by T&F discipline were made using Injury Proportion Ratios (IPR) and injury-associated time loss comparisons by injury type and sex were made using Negative Binomial Regression.

Results

Four hundred and seventy-four injuries were reported, 13.1% of which were classified as recurrent injuries. T&F athletes who competed in jumps experienced a lower proportion of recurrent injuries (6.1%) than runners (14.6%) and throwers (19.2%) (Recurrent IPR 0.40, 95% CI 0.18-0.88, p<0.05). When controlling for sex and injury diagnosis, T&F athletes experienced 50% greater time loss from sport following a recurrent injury than an initial injury (95% CI 17%-107%, p<0.01).

Conclusions

Recurrent injuries in T&F athletes account for greater time loss than initial injuries, despite sex or injury diagnosis. The current study indicates a need for further research to assess factors contributing to time loss.

Level of Evidence

Level 3.

Epidemiology of NCAA Track and Field Injuries From 2010 to 2014

Background:

Track and field (T&F) athletes compete in a variety of events that require different skills and training characteristics. Descriptive epidemiology studies often fail to describe event-specific injury patterns.

Purpose:

To describe the epidemiology of injuries in National Collegiate Athletic Association (NCAA) T&F by sex, setting (practice vs competition), and time of season (indoor vs outdoor) and to compare injury patterns by events within the sport.

Study Design:

Descriptive epidemiology study.

Methods:

Data were obtained from the NCAA Injury Surveillance Program for all indoor and outdoor T&F injuries during the academic years 2009-2010 to 2013-2014. Injury rates, injury rate ratios, and injury proportion ratios (IPRs) were reported and compared by sex, injury setting, season, and event. Analysis included time-loss as well as no-time loss injuries.

Results:

Over the 5 seasons, the overall injury rate was 3.99 injuries per 1000 athletic-exposures (95% CI, 3.79-4.20). After controlling for injury diagnoses, women’s T&F athletes experienced an 18% higher risk of injury (95% CI, 7% to 31%) and missed 41% more time after an injury (95% CI, 4% to 93%) when compared with men. Among all athletes, the injury risk during competition was 71% higher (95% CI, 50% to 95%) compared with practice and required 59% more time loss (95% CI, 7% to 135%). Distance running accounted for a significantly higher proportion of overuse injuries (IPR, 1.70; 95% CI, 1.40-2.05; P < .05) and required 168% more time loss (95% CI, 78% to 304%) than other events. The hip and thigh were the body regions most commonly injured; injury type, however, varied by T&F event. Sprinting accounted for the greatest proportion of hip and thigh injuries, distance running had the greatest proportion of lower leg injuries, and throwing reported the greatest proportion of spine and upper extremity injuries.

Conclusion:

Injury risk in NCAA T&F varied by sex, season, and setting. Higher injury rates were found in women versus men, indoor versus outdoor seasons, and competitions versus practices. The hip and thigh were the body regions most commonly injured; however, injury types varied by event. These findings may provide insight to programs aiming to reduce the risk of injury and associated time loss in collegiate T&F.

Runner's Health Choices Questionnaire: Male College Cross-Country Runners' Perspectives on Health and Eating

CONTEXT

Competitive cross-country runners train at much higher loads and with greater demands than recreational runners, posing a unique set of physiological and psychological challenges. Thus, identification of factors influencing health and nutritional choices in male cross-country runners is needed to help combat energy-related health issues.

PURPOSE

To assess male college cross-country runners' perspectives regarding sport-related health and the factors impacting their eating behaviors.

DESIGN

Cross-sectional survey.

PARTICIPANTS/METHODS

The Runner's Health Choices Questionnaire was distributed to male college cross-country runners. Responses were analyzed using quantitative descriptive statistics.

RESULTS

One hundred nineteen runners completed the survey. Runners reported a diverse range of factors impacting eating and health behaviors from athletic performance enhancement to enjoyment of food. Less than 6% of athletes ranked athletic trainer, registered dietitian, or physician as often consulted for nutrition/health information. However, 75% of runners said they would be somewhat likely or very likely to make dietary or health changes if given new or additional information by a health care provider.

CONCLUSION

Male cross-country runners appear to try to balance a global desire to be healthy with individual preferences. Athletes may be receptive to nutritional education that utilizes a biopsychosocial model with mental and psychological health support, and intentional effort is needed to support runners' overall health.

A systematic review of running-related musculoskeletal injuries in runners

OBJECTIVE

Running-related musculoskeletal injuries (RRMIs), especially stemming from overuse, frequently occur in runners. This study aimed to systematically review the literature and determine the incidence and prevalence proportion of RRMIs by anatomic location and specific pathology.

METHODS

An electronic database search with no date beginning restrictions was performed in SPORTDiscus, PubMed, and MEDLINE up to June 2020. Prospective studies were used to find the anatomic location and the incidence proportion of each RRMI, whereas retrospective or cross-sectional studies were used to find the prevalence proportion of each RRMI. A separate analysis for ultramarathon runners was performed.

RESULTS

The overall injury incidence and prevalence were 40.2% ± 18.8% and 44.6% ± 18.4% (mean ± SD), respectively. The knee, ankle, and lower leg accounted for the highest proportion of injury incidence, whereas the knee, lower leg, and foot/toes had the highest proportion of injury prevalence. Achilles tendinopathy (10.3%), medial tibial stress syndrome (9.4%), patellofemoral pain syndrome (6.3%), plantar fasciitis (6.1%), and ankle sprains (5.8%) accounted for the highest proportion of injury incidence, whereas patellofemoral pain syndrome (16.7%), medial tibial stress syndrome (9.1%), plantar fasciitis (7.9%), iliotibial band syndrome (7.9%), and Achilles tendinopathy (6.6%) had the highest proportion of injury prevalence. The ankle (34.5%), knee (28.1%), and lower leg (12.9%) were the 3 most frequently injured sites among ultramarathoners.

CONCLUSION

The injury incidence proportions by anatomic location between ultramarathoners and non-ultramarathoners were not significantly different (p = 0.798). The pathologies with the highest incidence proportion of injuries were anterior compartment tendinopathy (19.4%), patellofemoral pain syndrome (15.8%), and Achilles tendinopathy (13.7%). The interpretation of epidemiological data in RRMIs is limited due to several methodological issues encountered.

Epidemiology of Injuries in National Collegiate Athletic Association Men's Cross-Country: 2014-2015 Through 2018-2019

CONTEXT

The National Collegiate Athletic Association has sponsored men's cross-country programs since 1938, and the sport has grown greatly in scope since then.

BACKGROUND

Routine examinations of men's cross-country injuries are important for identifying emerging temporal patterns.

METHODS

Exposure and injury data collected in the National Collegiate Athletic Association Injury Surveillance Program during 2014-2015 through 2018-2019 were analyzed. Injury counts, rates, and proportions were used to describe injury characteristics, and injury rate ratios were used to examine differential injury rates.

RESULTS

The overall injury rate was 4.01 per 1000 athlete-exposures (AEs). Most reported injuries were inflammatory conditions (30.2%), strains (18.7%), and sprains (11.5%); rates of inflammatory conditions were highest in preseason. The most commonly reported injuries were lateral ligament complex tears (ankle sprains; 8.2%).

SUMMARY

Findings of this study were not entirely consistent with existing evidence; continued monitoring of competition injury rates and rates of commonly reported injuries is needed beyond 2018-2019.

Epidemiology of Injuries in National Collegiate Athletic Association Women's Cross-Country: 2014-2015 Through 2018-2019

CONTEXT

Women's cross-country is a thriving sport at the National Collegiate Athletic Association (NCAA) level with over 1000 sponsored programs association-wide.

BACKGROUND

Routine examinations of women's cross-country injuries are important for identifying emerging time trends in injury incidence and outcomes.

METHODS

Exposure and injury data collected in the NCAA Injury Surveillance Program from 2014-2015 through 2018-2019 were analyzed. Injury counts, rates, and proportions were used to describe injury characteristics, and injury rate ratios were used to examine differential injury rates.

RESULTS

The overall injury rate was 3.96 per 1000 athlete-exposures. Most reported injuries were inflammatory conditions (33.6%), strains (17.7%), and fractures (9.1%). The most commonly reported injuries were medial tibial stress syndrome (10.0%) and lateral ligament complex tears (ankle sprains; 4.2%).

SUMMARY

Findings of this study were not entirely consistent with existing evidence. Future studies are needed to examine the nature of inflammatory conditions and fractures in this population, as well as temporal patterns in commonly reported injuries.

Use of wearable sensors to identify biomechanical alterations in runners with Exercise-Related lower leg pain

Exercise-related lower leg pain (ERLLP) is one of the most prevalent running-related injuries, however little is known about injured runners' mechanics during outdoor running. Establishing biomechanical alterations among ERLLP runners would help guide clinical interventions. Therefore, we sought to a) identify defining biomechanical features among ERLLP runners compared to healthy runners during outdoor running, and b) identify biomechanical thresholds to generate objective gait-training recommendations. Thirty-two ERLLP (13 M, age: 21 ± 5 years, BMI: 22.69 ± 2.25 kg/m²) and 32 healthy runners (13 M, age: 23 ± 6 years, BMI: 22.33 ± 3.20 kg/m²) were assessed using wearable sensors during one week of typical outdoor training. Step-by-step data were extracted to assess kinetic, kinematic, and spatiotemporal measures. Preliminary feature extraction analyses were conducted to determine key biomechanical differences between healthy and ERLLP groups. Analyses of covariance (ANCOVA) and variability assessments were used compare groups on the identified features. Participants were split into 3 pace bands, and mean differences across groups were calculated to establish biomechanical thresholds. Contact time was the key differentiating feature for ERRLP runners. ANCOVA assessments reflected that the ERLLP group had increased contact time (Mean Difference [95% Confidence Interval] = 8 ms [6.9,9.1], p < .001), and approximate entropy analyses reflected greater contact time variability. Contact time differences were dependent upon running pace, with larger between-group differences being exhibited at faster paces. In all, ERLLP runners demonstrated longer contact time than healthy runners during outdoor training. Clinicians should consider contact time when assessing and treating these ERLLP runner patients.

Evaluation of Athletes with Hip Pain

Hip pain is a common complaint in athletes and can result in a significant amount of time lost from sport. Diagnosis of the source of hip pain can be a clinical challenge because of the deep location of the hip and the extensive surrounding soft tissue envelope. Establishing whether the source of hip pain is intra-articular or extra-articular is the first step in the process. A thorough history and a consistent and comprehensive physical examination are the foundation for the proper management of athletes with hip pain.

Characteristics of Injuries Occurring During Cross-Country: A Report from the Athletic Training Practice-Based Research Network

CONTEXT

Cross-country is a popular sport activity, particularly in adolescent populations. Although epidemiologic investigations have provided insight into patient and injury characteristics associated with running injuries, little is known about how these injuries are managed at the point of care.

OBJECTIVE

To describe injury and treatment characteristics of injuries sustained during cross-country.

DESIGN

Cross-sectional study.

SETTING

High school athletic training clinics within the Athletic Training Practice-Based Research Network.

PATIENTS OR OTHER PARTICIPANTS

Patient cases were included if the patient was diagnosed with an injury that occurred during interscholastic cross-country participation. All patients received usual care by an athletic trainer.

MAIN OUTCOME MEASURE(S)

We used summary statistics to describe injury (sex, age, participation level, time of injury, mechanism of injury, body part, injury type, diagnosis) and treatment (type, amount, duration, number of services) characteristics.

RESULTS

Most cross-country injuries occurred to the lower extremity and were musculotendinous or ligamentous in nature. The most common injury types were sprain/strain (43.8%), tendinopathy (18.5%), and general pain (9.5%). Injured body parts and diagnoses were typically similar between sexes. The most frequently used treatment was therapeutic exercises or activities (28.7%), and patients received an average of 7.4 ± 17.4 total athletic training services during 5.5 ± 15.1 episodes of care over 27.8 ± 87.5 days.

CONCLUSIONS

Adolescent cross-country student-athletes frequently sustained non-time-loss injuries that required up to 1 month of treatment and management. These findings will generate awareness surrounding the role of athletic trainers in providing care for cross-country athletes.

A comparison of ground reaction force waveforms and step length between recreational endurance runners with hamstring injuries and healthy controls

BACKGROUND

Acute hamstring injuries during sprinting have been attributed, in part, to the ground reaction forces experienced during early stance. However, no studies have investigated the factors associated with overuse hamstring injuries in endurance runners. Our purpose was to compare early stance ground reaction forces and step length between runners with overuse hamstring injuries and healthy controls.

METHODS

23 runners (5 men/ 18 women) who presented to a running clinic with an overuse hamstring injury were matched with healthy controls for sex, running speed and age. All participants ran on an instrumented treadmill, embedded with force plates. A 3-min warm-up was given, at a self-selected training pace, followed by 16-s of ground reaction force data collection (≈20 strides). Statistical parametric mapping was used to compared ground reaction force waveforms. Additionally, discrete force variables were calculated, including vertical average/instantaneous. Mean comparisons for discrete ground reaction force variables and step length were performed.

FINDINGS

Differences in ground reaction force waveforms did not reach statistical significance (p > 0.05). However, mean vertical loading rates were found to be higher in the Hamstring Injury group compared to Controls (p = 0.03-0.04) with small to moderate effect sizes (d = 0.47-0.52). No differences were found in mean step length.

INTERPRETATION

These results provide evidence that vertical loading rates may be associated with overuse hamstring injuries. However, further research is needed to identify the contribution of joint kinematics/kinetics and muscle activity.

Running behaviors, motivations, and injury risk during the COVID-19 pandemic: A survey of 1147 runners

The COVID-19 pandemic has influenced activity behaviors worldwide. Given the accessibility of running as exercise, gaining information on running behaviors, motivations, and running-related injury (RRI) risk during the pandemic is warranted. The purpose of this study was to assess the influence of the COVID-19 pandemic on running volume, behaviors, motives, and RRI changes from the year prior to the pandemic to the timeframe during social isolation restrictions. Runners of all abilities were recruited via social media to complete a custom Qualtrics survey. Demographics, running volume, behaviors, motivations, and injury status were assessed for the year prior to the pandemic, and during social isolation measures. Descriptive statistics and Student’s t-tests were used to assess changes in running outcomes during the pandemic. Logistic regressions were used to assess the influence of demographics on running behaviors and injury. Adjusted RRI risk ratios were calculated to determine the odds of sustaining an injury during the pandemic. Alpha was set to.05 for all analyses. A total of 1147 runners (66% females, median age: 35 years) across 15 countries (96% United States) completed the survey. Runners reported increased runs per week (Mean Difference with Standard Error [MD]: 0.30 [0.05], p < .001), sustained runs (MD: 0.44 [0.05], p < .001), mileage (MD: 0.87 [0.33], p = .01), and running times of day (MD: 0.11 [0.03], p < .001) during the pandemic, yet reported less workouts (i.e. sprint intervals; MD: -0.33 [0.06], p < .001), and less motives (MD [SE]: -0.41 [0.04], p < .001). Behavior changes were influenced by running experience and age. There was 1.40 (CI: 1.18,1.61) times the RRI risk during the pandemic compared to prior to the social isolation period. The COVID-19 pandemic influenced runners’ behaviors with increased training volume, decreased intensity and motivation, and heightened injury risk. These results provide insights into how physical activity patterns were influenced by large-scale social isolation directives associated with the pandemic.

Predisposing Risk Factors for Stress Fractures in Collegiate Cross-Country Runners

ABSTRACT

Giffin, KL, Knight, KB, Bass, MA, and Valliant, MW. Predisposing risk factors and stress fractures in collegiate cross-country runners. J Strength Cond Res 35(1): 227-232, 2021-The purpose of this study was to explore factors associated with increased stress fractures in collegiate cross-country runners. Subjects in this study were 42 male and female cross-country runners at a Division I university. Each athlete completed a questionnaire regarding smoking status, vitamin/mineral intake, previous stress fracture history, birth control usage, menstrual status, and demographic information. Nutritional assessment using a 3-day food record and measurements of whole body, lumbar spine, and hip bone mineral densities (BMDs) were also conducted on each athlete. Results indicated that 40% of the female and 35% of the male runners reported a history of stress fracture, and that all of them did not meet the recommended daily energy intake or adequate intakes for calcium or vitamin D required for their amount of training. Two-tailed t-test found statistically higher incidences of lumbar spine BMD in male and female runners whose daily calcium and vitamin D intakes were below minimum requirements as well as for women whose caloric intake was below the required level. When data on the lumbar spine was evaluated, 31% of subjects (31.8% of the male and 30% of the female runners) were identified as having osteopenia and 4.8% with osteoporosis. Results warrant a need for future longitudinal studies.

Association Between Knee- and Hip-Extensor Strength and Running-Related Injury Biomechanics in Collegiate Distance Runners

CONTEXT

Running-related injuries are common in distance runners. Strength training is used for performance enhancement and injury prevention. However, the association between maximal strength and distance-running biomechanics is unclear.

OBJECTIVE

To determine the relationship between maximal knee- and hip-extensor strength and running biomechanics previously associated with injury risk.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 36 collegiate distance runners (26 men, 10 women; age = 20.0 ± 1.5 years, height = 1.74 ± 0.09 m, mass = 61.97 ± 8.26 kg).

MAIN OUTCOME MEASURE(S)

Strength was assessed using the 1-repetition maximum (1RM) back squat and maximal voluntary isometric contractions of the knee extensors and hip extensors. Three-dimensional running biomechanics were assessed overground at a self-selected speed. Running variables were the peak instantaneous vertical loading rate; peak forward trunk-lean angle; knee-flexion, internal-rotation, and -abduction angles and internal moments; and hip-extension, internal-rotation, and -adduction angles and internal moments. Separate stepwise linear regression models were used to examine the associations between strength and biomechanical outcomes (ΔR2) after accounting for sex, running speed, and foot-strike index.

RESULTS

Greater 1RM back-squat strength was associated with a larger peak knee-flexion angle (ΔR2 = 0.110, ΔP = .045) and smaller peak knee internal-rotation angle (ΔR2 = 0.127, ΔP = .03) and internal-rotation moment (ΔR2 = 0.129, ΔP = .03) after accounting for sex, speed, and foot-strike index. No associations were found between 1RM back-squat strength and vertical loading rate, trunk lean, or hip kinematics and kinetics. Hip- and knee-extensor maximal voluntary isometric contractions were also not associated with any biomechanical variables.

CONCLUSIONS

Greater 1RM back-squat strength was weakly associated with a larger peak knee-flexion angle and smaller knee internal-rotation angle and moment in collegiate distance runners. Runners who are weaker in the back-squat exercise may exhibit running biomechanics associated with the development of knee-related injuries.

Achilles tendon single bout and season long adaptations during early and late collegiate cross-country season

AIMS

To examine single bout and season long Achilles tendon cross-sectional area (CSA) changes before and after running during the early and late cross-country season.

DESIGN

OBSERVATIONAL: repeated measures design study.

SETTING

Controlled laboratory setting.

PARTICIPANTS

This study consisted of 35 participants. The running group included 11 males and 9 females, the control group was 8 males and 7 females.

MAIN OUTCOME MEASURES

Diagnostic ultrasound images were taken before and after runners completed a common recovery run during the early and late cross-country season. Ultrasound images of control participants, who did not run, were taken following an averaged time that athletes spent running.

RESULTS

No significant tendon season long CSA increases occurred for runners (p = 0.453). Runners experienced significant Achilles tendon CSA decreases compared within subjects (p < 0.05) and between controls (p < 0.05). Significant CSA decreases occurred for runners during the early and late season run (p < 0.05) with greater percentages of decrease in the early season (p = 0.009). Male and female runners experienced similar CSA decreases while running (p = 0.696).

CONCLUSIONS

No Achilles tendon CSA increases occurred over the season. Significant Achilles tendon CSA decreases occurred while running during early and late season runs, but varied with larger CSA decreases occurring during the early season.

One in four trail running race entrants sustained an injury in the 12 months training preceding the 2019 SkyRun race

OBJECTIVE

To determine the epidemiology and clinical characteristics of RRIs among trail runners who entered the 2019 SkyRun races.

DESIGN

Descriptive cross-sectional study.

SETTING

2019 SkyRun races.

PARTICIPANTS

Consent for data analysis was given by 305 of 412 (74%) race entrants.

MAIN OUTCOME MEASURES

Retrospective annual incidence (RRIs/1000 h), point prevalence (%), frequency (%), characteristics (anatomical region, body area, tissue type, pathology type) and injury severity (mean severity score; 95% CI) of RRIs.

RESULTS

28.2% of participants reported at least one RRI. The retrospective annual incidence was 49.5 RRIs per 1000h and the point prevalence was 1.3%. Most injuries occurred in the lower limb (87.3%), with the knee (26.5%), ankle (21.6%), and foot (16.7%) reported as the most frequently injured body areas. Muscle/tendon accounted for 44.1% of tissue type injuries. Tendinopathy (27.5%), joint sprain (19.6%), and muscle injury (15.7%) were the most common pathology types reported. The mean injury severity score was 31.6.

CONCLUSIONS

One in 4 trail runners reported at least one RRI in the 12 months leading up to a race. RRIs mostly affected the lower limb specifically the knee, ankle and foot. Future research should establish injury risk factors to ultimately develop specific injury prevention strategies.

Relationship among maximum hip isometric strength, hip kinematics, and peak gluteal muscle force during running

OBJECTIVE

To determine if there is a relationship among isometric hip strength, hip kinematics, and peak gluteal muscle forces in cross-country runners during running.

DESIGN

Cross Sectional.

SETTING

University Biomechanics Laboratory.

PARTICIPANTS

Forty-six NCAA Division III collegiate cross-country runners (18 males, 28 females).

MAIN OUTCOME MEASURES

Pearson correlation coefficients were used to describe relationships among isometric hip strength, hip kinematics, and peak gluteal muscle forces during the stance phase of running. Strength of correlations were interpreted as little to no relationship (r < 0.25), fair relationship (0.25 ≤ r < 0.5), moderate relationship (0.5 ≤ r < 0.75), and strong relationship (r ≥ 0.75). Correlations were considered significant if p < 0.05.

RESULTS

Little to no relationships were found among isometric hip strength and gluteal muscle forces during running (r < 0.25). A fair relationship was present between prone external rotation isometric hip strength and peak hip adduction (0.25 <r < 0.5). Little to no relationship was shown between gluteus medius force and hip internal rotation. Moderate relationships were present among peak gluteus medius and minimus muscle forces and peak hip adduction (0.5 <r < 0.75).

CONCLUSION

Isometric hip strength does not appear to be related to gluteal muscle forces and hip kinematics during the stance phase of running while gluteal muscle force was moderately related to hip adduction. Factors other than strength may be related to muscle force production and hip kinematics during running.

Implementation of Injury and Illness Surveillance Protocols in Varsity Athletes

OBJECTIVE

To develop and implement a prospective varsity athlete surveillance system to identify injury and illness trends in a multisport varsity-level university setting.

DESIGN

Longitudinal prospective surveillance study.

SETTING

Varsity-level sport program at the University of Guelph, Guelph, ON, Canada.

PARTICIPANTS

Athletic therapists (ATs) (n = 35) from 17 varsity sports provided injury and illness information on 624 varsity-level athletes (381 men and 243 women) during the 2016/2017 competitive season.

INTERVENTIONS

Team ATs reported athlete health complaints weekly. Athletes reported additional details on the injury or illness that was reported.

MAIN OUTCOME MEASURES

The outcome measurements included when the injury or illness occurred, anatomical location, diagnosis, cause, perceived severity, treatment, estimated athlete exposure (AE) to training and competition, and time loss from sport. Measures were recorded from the teams' first competition through to the end the season and/or playoffs.

RESULTS

Twenty-nine of 30 varsity sports teams participated in this injury and illness surveillance protocol. The compliance of team ATs and varsity athletes was 89% (men: 94%, women: 82%). The overall injury and illness rates were 5.5 injuries and 1.7 illnesses per 1000 AEs, respectively. Men's injury rates were greater than women's, and injury rates of contact sports were greater than noncontact sports.

CONCLUSIONS

The utilization of a prospective injury and illness surveillance protocol in the Canadian University sport system is feasible with good athlete, AT, and coach acceptance. The surveillance data should inform future injury and illness prevention strategies.

THE EFFECT OF AN ANTI-GRAVITY TREADMILL ON RUNNING CADENCE

BACKGROUND

Running cadence, or step rate, is often measured in running gait analysis and manipulated in gait retraining. A lower body positive pressure treadmill, or anti-gravity treadmill, allows users to walk/run in a reduced gravity environment.

PURPOSE

The primary purpose of this study was to determine how natural running cadence is affected by running on an anti-gravity treadmill compared to a standard treadmill in a healthy, active population. The secondary purpose was to determine if natural and increased cadence is affected by amount of body weight support.

STUDY DESIGN

Cross-sectional study (convenience sample).

METHODS

Thirty participants were recruited to run on an anti-gravity treadmill (AlterG Anti-Gravity Treadmill^TM M320) at their pre-determined, self-selected, comfortable treadmill speed. Cadence was recorded at nine randomized bodyweight conditions, ranging from 100% of body weight to 20% of body weight, in 10% increments. An additional nine participants were recruited to try to replicate their natural, standard treadmill cadence, as well as increase it by 5% and 10%, while on an anti-gravity treadmill with the same randomized body weight conditions.

RESULTS

Thirty participants, 19 females and 11 males, mean age 27.3 years (range, 22-45), completed Part 1 of the study protocol, while nine additional participants (2 females and 7 males) with a mean age of 29.6 years old (range, 25-40 years) completed Part 2 of the protocol. There was a significant effect of natural running cadence on the anti-gravity treadmill at reduced body weight percentages (p<.01). Post-hoc t-tests revealed that every 10% bodyweight interval was significantly lower than the previous 10% interval (p<.01) on the anti-gravity treadmill, with cadence decreases ranging from 1.5%-3.5% between intervals. Seven of the nine (77.8%) participants in Part 2 were able to replicate and increase their cadence at all body weight levels on the anti-gravity treadmill.

CONCLUSIONS

Decreasing bodyweight level on an anti-gravity treadmill yields a significant and linear decrease in running cadence when performed at a self-selected, moderate intensity pace. Further, the vast majority of participants were able to successfully replicate and increase cadence at all levels of bodyweight percentage.

The Demographics of Fractures and Dislocations Across the Entire United States due to Common Sports and Recreational Activities

BACKGROUND

There exists little nationwide data regarding fracture and dislocation patterns across a wide variety of sporting activities for all ages and sexes.

HYPOTHESIS

Participant demographics (age and sex) will vary with regard to fracture and joint dislocation sustained during sport-related activities.

STUDY DESIGN

Descriptive epidemiology study.

LEVEL OF EVIDENCE

Level 3.

METHODS

The National Electronic Injury Surveillance System All Injury Program data 2005 through 2013 were accessed; 18 common sports and recreational activities in the United States were selected. Statistical software was used to calculate the numbers of fractures and dislocations, and incidence was calculated using US Census Bureau data. Multivariate logistic regression analysis determined the odds ratios (ORs) for the occurrence of a fracture or dislocation.

RESULTS

A fracture occurred in 20.6% and a joint dislocation in 3.6% of the emergency department visits for sports-related injuries; annual emergency department visit incidence was 1.51 for fractures and 0.27 for dislocations (per 1000 people). Most of the fractures occurred in football (22.5%). The OR for fracture was highest for inline skating (OR, 6.03), males (OR, 1.21), Asians, whites, and Amerindians compared with blacks (OR, 1.46, 1.25, and 1.18, respectively), and those older than 84 years (OR, 4.77). Most of the dislocations occurred in basketball (25.7%). The OR for dislocation was highest in gymnastics (OR, 4.08), males (OR, 1.50), Asians (OR, 1.75), and in those aged 20 to 24 years (OR, 9.04). The most common fracture involved the finger, and the most common dislocation involved the shoulder.

CONCLUSION

Inline skating had the greatest risk for fracture, and gymnastics had the greatest risk for joint dislocation.

CLINICAL RELEVANCE

This comprehensive study of the risks of sustaining a fracture or dislocation from common sports activities across all age groups can aid sports health providers in a better understanding of those sports at high risk and be proactive in prevention mechanisms (protective gear, body training).

Perceptions of Overuse Injury Among Swedish Ultramarathon and Marathon Runners: Cross-Sectional Study Based on the Illness Perception Questionnaire Revised (IPQ-R)

Background

Long-distance runners’ understandings of overuse injuries are not well known which decreases the possibilities for prevention. The common sense model (CSM) outlines that runners’ perceptions of a health problem can be described using the categories identity, consequence, timeline, personal control, and cause. The aim of this study was to use the CSM to investigate perceptions of overuse injury among long-distance runners with different exercise loads.

Methods

The study used a cross-sectional design. An adapted version of the illness perception questionnaire revised (IPQ-R) derived from the CSM was used to investigate Swedish ultramarathon and marathon runners’ perceptions of overuse injuries. Cluster analysis was employed for categorizing runners into high and low exercise load categories. A Principal Component Analysis was thereafter used to group variables describing injury causes. Multiple logistic regression methods were finally applied using high exercise load as endpoint variable and CSM items representing perceptions of injury identity, consequence, timeline, personal control, and causes as explanatory variables.

Results

Complete data sets were collected from 165/443 (37.2%) runners. The symptoms most commonly associated with overuse injury were pain (80.1% of the runners), stiff muscles (54.1%), and stiff joints (42.0%). Overuse injury was perceived to be characterized by the possibility of personal control (stated by 78.7% of the runners), treatability (70.4%), and that the injury context was comprehensible (69.3%). The main injury causes highlighted were runner biomechanics (stated by 78.3%), the runner’s personality (72.4%), and running surface biomechanics (70.0%). Among men, a belief in that personality contributes to overuse injury increased the likelihood of belonging to the high exercise load category [Odds ratio (OR) 2.10 (95% Confidence interval (95% CI) 1.38–3.19); P = 0.001], while beliefs in that running biomechanics [OR 0.56 (95% CI 0.37–0.85); P = 0.006) and mileage (OR 0.72 (95% CI 0.54–0.96); P = 0.026] causes injury decreased the likelihood. In women, a strong perception that overuse injuries can be controlled by medical interventions decreased the likelihood of high exercise load [OR 0.68 (95% CI 0.52–0.89); P = 0.005].

Conclusion

This study indicates that recognition among long-distance runners of the association between own decisions in overuse injury causation is accentuated by increased exercise loads.

The Proportion of Lower Limb Running Injuries by Gender, Anatomical Location and Specific Pathology: A Systematic Review

Running is associated with a higher risk of overuse injury than other forms of aerobic exercise such as walking, swimming and cycling. An accurate description of the proportion of running injuries per anatomical location and where possible, per specific pathology, for both genders is required. The aim of this review was to determine the proportion of lower limb running injuries by anatomical location and by specific pathology in male and female runners (≥800m - ≤ marathon). The preferred reporting items for systematic reviews and meta-analyses guidelines were followed for this review. A literature search was performed with no restriction on publication year in Web of Science, Scopus, Sport-Discus, PubMed, and CINAHL up to July 2017. Retrospective, cross-sectional, prospective and randomised-controlled studies which surveyed injury data in runners were included. 36 studies were included to report the overall proportion of injury per anatomical location. The overall proportion of injury by specific pathology was reported from 11 studies. The knee (28%), ankle-foot (26%) and shank (16%) accounted for the highest proportion of injury in male and female runners, although the proportion of knee injury was greater in women (40% vs. 31%). Relative to women, men had a greater proportion of ankle-foot (26% vs. 19%) and shank (21% vs. 16%) injuries. Patellofemoral pain syndrome (PFPS; 17%), Achilles tendinopathy (AT; 10%) and medial tibial stress syndrome (MTS; 8%) accounted for the highest proportion of specific pathologies recorded overall. There was insufficient data to sub-divide specific pathology between genders. The predominate injury in female runners is to the knee. Male runners have a more even distribution of injury between the knee, shank and ankle-foot complex. There are several methodological issues, which limit the interpretation of epidemiological data in running injury.

A systematic review of injuries in gymnastics

OBJECTIVES

To identify all studies of gymnastics injuries and assess injury rates, types, locations, and causes.

METHODS

Seven electronic and two grey literature databases were searched. Two reviewers independently assessed titles/abstracts, abstracted data, and calculated average rates weighted by study size.

RESULTS

One study (n = 963) of three Olympic games (2008,2012,2016) provided injury rates for females of 86.4/1000gymnasts and males 79.9. For 29 databases one study of males (n = 64) provided a rate of 8.8 injuries/1000hours/AE (AE = athletic-exposure) and three of females varied rates (8.5, 9.4, and 91). Three studies for males (n = 153) provided a weighted average rate of 1.4 injuries/1000hours/training, and for females six studies (n = 476) 1.5 injuries. Four studies of males (n = 286) provided a weighted average of 678 injuries/1000gymnasts per year and eight studies of females (n = 1,764) a rate of 306. Of 19 surveys, eight provided rates for females (n = 1,463) of 596 injuries/gymnast per year and two for males (n = 40) a rate of 1,036. In the Olympics injuries were preponderately lower limb (63%) then trunk (23%) and upper limb (14%); injury type was sprains (35%) followed by tendinopathy/arthritis/impingements (17%), contusions (10%), and fractures (7%). Five database studies provided injury location data for 274 males: averages weighted by study size were upper extremity 42.8%, lower extremity 33.6%, torso/spine 11.8%, and head/neck 4.9% and 12 studies with 843 females provided average rates for lower extremity 51%, upper extremity 30.8%, torso/spine 13% and head/neck 0.8%. Official gymnastics organizations' websites provide no readily available data about injury rates or methods of prevention.

CONCLUSIONS

Studies need to collect comprehensive data for injury rates by training/competitions, gender, age, injury location/type/cause. Studies could assess whether trainers and physiotherapists monitoring gymnasts closely for injury risk would reduce injuries. Studies including randomized controlled trials (RCTs) of interventions in training, videotaping and performance feedback to reduce injury rates would be helpful.

Epidemiologic comparison of ankle injuries presenting to US emergency departments versus high school and collegiate athletic training settings

BACKGROUND

Ankle sprains account for a large proportion of injuries presenting to both United States (US) emergency departments (EDs) as well as high school (HS) and collegiate school athletic training settings. The epidemiologic differences across these settings by both sport and diagnosis have not been well differentiated. Ankle injury data from 3 national surveillance datasets. Athletic training setting data from the National High School Sports-Related Injury Surveillance System and the National Collegiate Athletic Association Injury Surveillance Program was from academic years 2009/10 through 2013/14 and the US Consumer Product Safety Commission's National Electronic Injury Surveillance System (ED setting) data was from calendar years 2009 through 2013. Data was analyzed for patients 14-22 years old participating in 12 sports (male football, baseball, basketball, lacrosse, soccer, and wrestling, and female softball, basketball, lacrosse, soccer, volleyball, and field hockey). We calculated sport-specific injury rates, proportions, and rate ratios (RRs) with 95% confidence intervals (CI).

RESULTS

During the study period, the surveillance systems captured 20,261 ankle injuries presenting to EDs plus 5546 HS and 2725 collegiate injuries presenting to school athletic training settings. Rates were higher in collegiate compared to HS athletes presenting in the athletic training setting. Football accounted for the largest proportion of ankle injuries presenting to HS (31.2%) and college (41.0%) athletic training settings; male basketball accounted for the largest proportion presenting to EDs among both HS (41.0%) and college (65.8%) aged patients. Sprains/strains accounted for over 80% of injuries in all three settings. Fractures accounted for a larger proportion of ankle injuries presenting to EDs (9.5%) compared to HS (3.8%) and college (0.8%) athletic training settings. There was no change in injury rates during the study period across the three settings.

CONCLUSIONS

Injury rates and patterns varied by sport and presentation setting, with athletic trainers evaluating more ankle injuries overall in the collegiate setting compared to the high school setting. Ankle injuries presenting to EDs were more commonly fractures, suggesting that more severe injuries present to this setting. Understanding the epidemiology of such patterns will help readers interpret differences in publications reporting data from varied clinical settings.

Epidemiology of Hip and Groin Injuries in Collegiate Athletes in the United States

Background:

Hip and groin pain is a common complaint among athletes. Few studies have examined the epidemiology of hip and groin injuries in collegiate athletes across multiple sports.

Purpose:

To describe the rates, mechanisms, sex-based differences, and severity of hip/groin injuries across 25 collegiate sports.

Study Design:

Descriptive epidemiology study.

Methods:

Data from the 2009-2010 through 2013-2014 academic years were obtained from the National Collegiate Athletic Association Injury Surveillance Program (NCAA ISP). The rate of hip/groin injuries, mechanism of injury, time lost from competition, and need for surgery were calculated. Differences between sex-comparable sports were quantified using rate ratios (RRs) and injury proportion ratios (IPRs).

Results:

In total, 1984 hip/groin injuries were reported, giving an overall injury rate of 53.06 per 100,000 athlete-exposures (AEs). An adductor/groin tear was the most common injury, comprising 24.5% of all injuries. The sports with the highest rates of injuries per 100,000 AEs were men’s soccer (110.84), men’s ice hockey (104.90), and women’s ice hockey (76.88). In sex-comparable sports, men had a higher rate of injuries per 100,000 AEs compared with women (59.53 vs 42.27, respectively; RR, 1.41 [95% CI, 1.28-1.55]). The most common injury mechanisms were noncontact (48.4% of all injuries) and overuse/gradual (20.4%). In sex-comparable sports, men had a greater proportion of injuries due to player contact than women (17.0% vs 3.6%, respectively; IPR, 4.80 [95% CI, 3.10-7.42]), while women had a greater proportion of injuries due to overuse/gradual than men (29.1% vs 16.7%, respectively; IPR, 1.74 [95% CI, 1.46-2.06]). Overall, 39.3% of hip/groin injuries resulted in time lost from competition. Only 1.3% of injuries required surgery.

Conclusion:

Hip/groin injuries are most common in sports that involve kicking or skating and sudden changes in direction and speed. Most hip/groin injuries in collegiate athletes are noncontact and do not result in time lost from competition, and few require surgery. This information can help guide treatment and prevention measures to limit such injuries in male and female collegiate athletes.

Biomechanical, metabolic and cardiopulmonary responses of masters recreational runners during running at different speeds

This study tested interactions between age and running speed on biomechanics, metabolic responses and cardiopulmonary responses. Three-hundred participants ran at preferred and standardized speeds. Age group (younger, masters [≥40 years]) by speed (self-selected 8.8 km/h, 11.2 km/h and 13.6 km/h) interactions were tested on main outcomes of sagittal kinematic, temporal spatial, metabolic and cardiopulmonary parameters. At all speeds, angular displacements of the ankle, pelvis and knee were less in masters than younger runners (Hedges g effect size range = 0.30-1.04; all p < 0.05). A significant age group by speed interaction existed for hip angular displacement (Wald χ² = 10.753; p = 0.013). Masters runners ran at higher relative heart rates (p < 0.05) but at similar rates of oxygen use and energy expenditure. Masters runners used hip-dominant motion and step lengthening as running speed increased, but did not change centre of mass vertical displacement. This may increase mechanical stresses on tissues of the lower extremity in masters runners, especially hamstrings, hip joint and Achilles.

Perception of Health Problems Among Competitive Runners: A Qualitative Study of Cognitive Appraisals and Behavioral Responses

BACKGROUND

Approximately 2 of every 3 competitive runners sustain at least 1 health problem each season. Most of these problems are nontraumatic injuries with gradual onset. The main known risk indicator for sustaining a new running-related injury episode is a history of a previous injury, suggesting that behavioral habits are part of the causal mechanisms.

PURPOSE

Identification of elements associated with purposeful interpretations of body perceptions and balanced behavioral responses may supply vital information for prevention of health problems in runners. This study set out to explore competitive runners' cognitive appraisals of perceived symptoms on injury and illness and how these appraisals are transformed into behavior.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

The study population consisted of Swedish middle- and long-distance runners from the national top 15 list. Qualitative research methods were used to categorize interview data and perform a thematic analysis. The categories resulting from the analysis were used to construct an explanatory model.

RESULTS

Saturation of the thematic classification required that data from 8 male and 6 female runners (age range, 20-36 years) were collected. Symptoms interpreted to be caused by illness or injury with a sudden onset were found to lead to immediate action and changes to training and competition programs (activity pacing). In contrast, perceptions interpreted to be due to injuries with gradual onset led to varied behavioral reactions. These behavioral responses were planned with regard to short-term consequences and were characterized by indifference and neglect of long-term implications, consistent with an overactivity behavioral pattern. The latter pattern was consistent with a psychological adaptation to stimuli that is presented progressively to the athlete.

CONCLUSION

Competitive runners appraise whether a health problem requires immediate withdrawal from training based on whether the problem is interpreted as an illness and/or has a sudden onset. The ensuing behaviors follow 2 distinct patterns that can be termed "activity pacing" and "overactivity."

Epidemiology of 3825 injuries sustained in six seasons of National Collegiate Athletic Association men's and women's soccer (2009/2010-2014/2015)

AIM

To describe the epidemiology of National Collegiate Athletic Association (NCAA) men's and women's soccer injuries during the 2009/2010-2014/2015 academic years.

METHODS

This descriptive epidemiology study used NCAA Injury Surveillance Program (NCAA-ISP) data during the 2009/2010-2014/2015 academic years, from 44 men's and 64 women's soccer programmes (104 and 167 team seasons of data, respectively). Non-time-loss injuries were defined as resulting in <24 h lost from sport. Injury counts, percentages and rates were calculated. Injury rate ratios (RRs) and injury proportion ratios (IPRs) with 95% CIs compared rates and distributions by sex.

RESULTS

There were 1554 men's soccer and 2271 women's soccer injuries with injury rates of 8.07/1000 athlete exposures (AE) and 8.44/1000AE, respectively. Injury rates for men and women did not differ in competitions (17.53 vs 17.04/1000AE; RR=1.03; 95% CI 0.94 to 1.13) or practices (5.47 vs 5.69/1000AE; RR=0.96; 95% CI 0.88 to 1.05). In total, 47.2% (n=733) of men's soccer injuries and 47.5% (n=1079) of women's were non-time loss. Most injuries occurred to the lower extremity and were diagnosed as sprains. Women had higher concussion rates (0.59 vs 0.34/1000AE; RR=1.76; 95% CI 1.32 to 2.35) than men.

CONCLUSIONS

Non-time-loss injuries accounted for nearly half of the injuries in men's and women's soccer. Sex differences were found in competition injuries, specifically for concussion. Further study into the incidence, treatment and outcome of non-time-loss injuries may identify a more accurate burden of these injuries.