Biomechanical risk factors for running-related injury differ by sample population: A systematic review and meta-analysis

Biomechanical Changes During Running on a Lower Body Positive Pressure Treadmill in Competitive Runners

Lower body positive pressure treadmills (LBPPTs) offer precise body weight unloading for injury rehabilitation and performance training in runners. This study investigated biomechanical changes during running at varying body weight support (BWS) levels (0%-80%) in competitive runners, including sex-specific responses. Twenty-six runners (age: 33.6 ± 9.8 years; 15 female, 11 male) completed randomized 3-min running bouts at 12 km/h across nine BWS levels. Spatiotemporal parameters, plantar force, peak tibial acceleration, and running stability were measured using pressure insoles and inertial sensors placed at the tibia and foot. Our results revealed significant reductions in step rate (b = -0.24 steps•min-1/%BWS, p < 0.001), normalized ground contact time (b = -0.001 1/%BWS, p < 0.001), maximum plantar force (b = -0.010 BW/%BWS, p < 0.001), and peak tibial acceleration (b = -0.03 g/%BWS, p < 0.001) with increased BWS. Swing time increased (b = 1.50 ms/%BWS, p < 0.001), while stance time decreased (b = -0.41 ms/%BWS, p < 0.001). Running stability showed marginal changes (foot: b = -0.001 1/%BWS, p = 0.017; tibia: b = 0.001 1/%BWS, p = 0.009). Sex differences were observed in step rate (b = -6.79 steps•min-1, p = 0.045) and maximum plantar force (b = -0.128 BW, p = 0.034), but there were no significant sex × BWS interaction effects for any of the investigated parameters. Findings from this study highlight the effectiveness of LBPPTs for reducing musculoskeletal loading while revealing associated gait changes. Athletes, therapists, and coaches should consider individual biomechanical responses to optimize rehabilitation and performance strategies. Future research should explore long-term adaptations and injury prevention outcomes.

Optimal control simulations tracking wearable sensor signals provide comparable running gait kinematics to marker-based motion capture

Objective

Inertial measurement units (IMUs) offer a method for assessing gait beyond the confines of a laboratory. Signal noise and calibration errors pose significant obstacles to accurately estimating joint angles, particularly during dynamic activities such as running. Advancements in dynamic optimisation tools could enable a more comprehensive analysis with fewer sensors and/or low-quality data. The objective of this study was to compare two IMU-based modelling approaches (inverse kinematics and optimal control simulations) with optical marker-based motion capture in reconstructing running gait kinematics.

Methods

Six participants performed treadmill running at three speeds whilst marker trajectories and IMU signals were collected concurrently. The subject-specific biomechanical model consisted of a 3D representation of the lower body and torso, with contact spheres added to simulate ground contact in the optimal control simulations. The objective of the optimal control simulations was to track the accelerations, angular velocities, and orientations of eight sensors with simulated signals from the model sensors. Additional constraints were enforced, reflecting physiological and biomechanical principles and targeting dynamic consistency. The objective of the IMU-based inverse kinematics was to minimize the difference between the input and simulated sensor orientations. The joint kinematics derived from both methods were compared against optical marker-based motion capture across a range of running speeds, evaluating the absolute and normalized root mean square errors.

Results

Compared with motion-capture joint angles, optimal control simulations resulted in lower absolute errors (RMSE 8° ± 1) that were consistent across all speeds. IMU-based inverse kinematics exhibited greater differences with motion capture (RMSE 12° ± 1), which was more significant at faster speeds. The largest absolute inaccuracies were observed in the sagittal angles when not normalizing for the joint range of motion. The computational times for the optimal control were 46 ± 60 min, whereas they were 19.3 ± 3.7 s for the IMU-based inverse kinematics.

Conclusions

Compared with traditional IMU-based inverse kinematics, the optimal control approach provides a more comparative representation of joint kinematics from optical motion capture. This method can mitigate errors associated with closely tracking IMU noise and drift, and it offers a dynamic analysis that considers the underlying forces and torques producing movement. However, these advantages come at the expense of challenges in parameter selection and computational cost.

Significance

These findings highlight the potential of using IMUs with optimal control methods to provide a comprehensive understanding of gait dynamics across diverse applications. IMU-based inverse kinematics remains a viable option for faster computation and when model fidelity is less of a concern.

The influence of high-intensity interval running bouts on distal anterior femoral cartilage in competitive distance and middle-distance runners

Competitive runners compared with recreational runners have increased odds of osteoarthritis and running-related injury, potentially from different running types. We compared distal anterior femoral cartilage deformation in competitive runners following a continuous and high-intensity interval run (10 × 400 m, 300 m jog) and evaluated the association between running kinetics and cartilage deformation. Twenty-four competitive runners (11 females and 13 males), between 18 and 35 years old underwent femoral cartilage ultrasound imaging before and after both running conditions in a counterbalanced order 2-7 days apart. Footwear was instrumented with force-sensing insoles to extract peak ground reaction force, loading rate, and impulse. A 2 (time) by 2 (condition) ANOVA with repeated measures evaluated the change in cartilage thickness after running between conditions. The lateral cartilage region showed greater deformation after interval compared with continuous running (p = 0.003). A main effect of time was seen where cartilage was thinner after running compared with baseline regardless of condition (1.92 (1.82, 2.02) vs. 1.83 (1.73, 1.93) mm; mean difference = -0.094 (-0.147, -0.042) mm, p = 0.001). No significant associations were found between cartilage deformation and loading rate, peak ground reaction force, or impulse (all r < 0.32, all p > 0.05). Interval running contributed to greater lateral distal anterior femoral cartilage deformation.

Estimating Ground Reaction Forces From Inertial Sensors

OBJECTIVE

Our aim is to determine if data collected with inertial measurement units (IMUs) during steady-state running could be used to estimate ground reaction forces (GRFs) and to derive biomechanical variables (e.g., contact time, impulse, change in velocity) using lightweight machine-learning approaches. In contrast, state-of-the-art estimation using LSTMs suffers from prohibitive inference times on edge devices, requires expensive training and hyperparameter optimization, and results in black box models.

METHODS

We proposed a novel lightweight solution, SVD Embedding Regression (SER), using linear regression between SVD embeddings of IMU data and GRF data. We also compared lightweight solutions including SER and k-Nearest-Neighbors (KNN) regression with state-of-the-art LSTMs.

RESULTS

We performed extensive experiments to evaluate these techniques under multiple scenarios and combinations of IMU signals and quantified estimation errors for predicting GRFs and biomechanical variables. We did this using training data from different athletes, from the same athlete, or both, and we explored the use of acceleration and angular velocity data from sensors at different locations (sacrum and shanks).

CONCLUSION

Our results illustrated that lightweight solutions such as SER and KNN can be similarly accurate or more accurate than LSTMs. The use of personal data reduced estimation errors of all methods, particularly for most biomechanical variables (as compared to GRFs); moreover, this gain was more pronounced in the lightweight methods.

SIGNIFICANCE

The study of GRFs is used to characterize the mechanical loading experienced by individuals in movements such as running, which is clinically applicable to identify athletes at risk for stress-related injuries.

Incidence, severity, and risk factors for injuries in female trail runners - A retrospective cross-sectional study

OBJECTIVES

To determine the incidence, severity, and nature of injuries sustained by female trail runners and investigate selected training variables as risk factors for injuries.

DESIGN

Cross-sectional, retrospective cohort study.

SETTING

Online questionnaire (Jisc Online Surveys).

PARTICIPANTS

Female trail runners (n = 62) aged 39.1 ± 12.4 years.

MAIN OUTCOME MEASURES

Training metrics (average weekly number of running sessions, mileage (km), session duration (mins), pace (min/km), ascent (m) and descent (m), number of running doubles per week, number of cross training doubles per week, type of cross training), incidence, severity and nature of trail running injuries sustained in the previous 12 months.

RESULTS

The injury incidence was 14.3 injuries per 1000 h and mean severity score (OSTRC- H) was 80.95 ± 21.74. The main anatomical region affected was the lower limb (63.4%), primarily the ankle (13.9%), knee (13.0%) and lower leg (12.2%). The most common injury was tendinopathy (25.2%). A higher number of injuries sustained in the previous 12 months was weakly associated with a higher average duration of other (not trail) weekly running sessions (p = 0.017).

CONCLUSIONS

Findings from this study could inform future injury prevention and treatment strategies. Prospective, longitudinal data on injuries in female trail runners is needed.

Risk factors for running-related injuries: An umbrella systematic review

PURPOSE

This umbrella systematic review (SR) of SRs and meta-analysis seeks to comprehensively synthesize existing literature to identify and consolidate the diverse range of risk factors contributing to running-related injuries (RRIs).

METHODS

Systematic searches were conducted on June 28, 2023, across Web of Science, SPORTDiscus, Scopus, PubMed, and Cochrane Library. We included SRs, whether accompanied by meta-analyses or not, that focused on investigating risk factors for RRIs within observational studies. The methodological quality of the SRs was evaluated using the Assessing the Methodological Quality of Systematic Reviews II. To assess the extent of overlap across reviews, the corrected covered area metric was calculated.

RESULTS

From 1509 records retrieved, 13 SRs were included. The degree of overlap between SRs was low (4%), and quality varied from critically low (n = 8) to low (n = 5). Two hundred seven outcomes assessed in 148 primary studies were identified as being associated with the occurrence of RRIs. The effect sizes of the associations for which risk measures were reported (n = 131) were classified as large (n = 30, 23%), medium (n = 38, 29%), small (n = 48, 37%) or no effect (n = 15, 11%). Running/training characteristics, health and lifestyle factors, along with morphological and biomechanical aspects, exhibit large effect sizes in increasing the risk for RRIs.

CONCLUSION

Drawing from the outcomes of the low-quality SRs and associations with large effect sizes, our findings indicate that running/training characteristics and health and lifestyle factors, as well as morphological and biomechanical aspects, are all implicated in elevating the risk of RRIs, emphasizing the multifactorial basis of injury incidence in running. Given the low quality and heterogeneity of SR, individual findings warrant cautious interpretation.

The reliability of wearable commercial sensors for outdoor assessment of running biomechanics: the effect of surface and running speed

The aim of this study was to investigate the reliability of running biomechanics assessment with a wearable commercial sensor (RunScribeTM). Participants performed multiple 200-m runs over sand, grass and asphalt ground at the estimated 5-km tempo, with an additional trial with 21-km tempo at the asphalt. Intra-session reliability was excellent for all variables at 5-km pace (intra-class coefficient correlation (ICC) asphalt: 0.90-0.99; macadam: 0.94-1.00; grass: 0.92-1.00), except for shock (good; ICC = 0.83), and contact time and total power output (moderate; ICC = 0.68-0.71). Coefficient of variation (CV) were mostly acceptable in all conditions, except for horizontal ground reaction force (GRF) rate in asphalt 5-km pace trial (CV = 24.5 %), power (CV = 14.3 %) and foot strike type (CV = 30.9 %) in 21-km pace trial, and horizontal GRF rate grass trial (CV = 15.7 %). Inter-session reliability was high or excellent for the majority of the outcomes (ICC≥0.85). Total power output (ICC = 0.56-0.65) and shock (ICC = 0.67-0.75) showed only moderate reliability across all conditions. Power (CV = 12.5-13.8 %), foot strike type (CV = 14.9-29.4 %) and horizontal ground reaction force rate (CV = 12.4-36.4 %) showed unacceptable CV.

Incidence and biomechanical risk factors for running-related injuries: A prospective cohort study

Background

Injuries among runners is significant, yet the contributing risk factors remain elusive. The objective of this study was to examined the incidence and biomechanical elements associated with running-related injuries.

Methods

A 24-week prospective study was carried out. Injury incidence was calculated per 1000 h of running, with participants completing bi-monthly online questionnaires. Biomechanical risk factors, encompassing plantar pressure, muscle strength of hip and knee muscles, core stability, dorsiflexion, passive hip internal rotation, lower extremity length, Q-angle, and shank-forefoot alignment, were assessed at baseline. Logistic regression was used to investigate the relationship between injury incidence and these biomechanical risk factors.

Results

Ninety-eight runners participated in the study. Injury incidence was 8.1 per 1000 h of running, with 41 runners experiencing musculoskeletal injuries during the follow-up period. The knee emerged as the most commonly affected joint, constituting 28.4 % of injuries. The Odds Ratio for hip external rotator muscle strength was .84 (95 % Confidence Interval = .71 - .99).

Conclusion

Greater force during hip external rotation was identified as a protective factor against running injuries. These findings bear significance for the formulation and implementation of preventive strategies.

Evidence of spontaneous cardiac-locomotor coupling during daily activities in healthy adults

Introduction

One way to improve exercise performance and protect heart health is the extended synchronization of the stepping with the diastolic phase of the cardiac cycle. Cardiac-locomotor coupling (CLC) happens when the step rate (SR) equals the heart rate (HR). The extent of CLC in daily life is unknown. This study aims to analyze spontaneous occurrences of CLC during daily activities.

Methods

A retrospective analysis of daily life recordings from a wrist-worn sensor was undertaken (PMData, N = 16, 5 months duration). The deviation between HR and SR was used to define CLC (deviation ≤ 1%) and weak CLC (1%< deviation ≤ 10%). The occurrence and the probability of CLC during everyday life were computed from the recordings. The CLC occurrences were stratified depending on the duration and intensity of the physical activity. Finally, a Monte Carlo simulation was run to evaluate the probability of random occurrences of CLC vs. the observed recordings.

Results

Participants couple for 5% and weakly couple for 35% of the observational period. The ratio of 1:1 between HR and SR is the dominating occurrence across the study population and this overrepresentation is significant. CLC occurs mostly for long activities. The extent of CLC for various intensities of activity is subject-dependent. The results suggest that CLC is feasible for most people.

Conclusions

CLC occurs spontaneously during unsupervised daily activity in everyone in our cohort, which suggests a mechanistic interaction between the cardiac and the locomotor systems. This interaction should be investigated for medical rehabilitation and sports applications in the future.

Comparison of ground reaction forces as running speed increases between male and female runners

Introduction: The biomechanics associated with human running are affected by gender and speed. Knowledge regarding ground reaction force (GRF) at various running speeds is pivotal for the prevention of injuries related to running. This study aimed to investigate the gait pattern differences between males and females while running at different speeds, and to verify the relationship between GRFs and running speed among both males and females. Methods: GRF data were collected from forty-eight participants (thirty male runners and eighteen female runners) while running on an overground runway at seven discrete speeds: 10, 11, 12, 13, 14, 15 and 16 km/h. Results: The ANOVA results showed that running speed had a significant effect (p < 0.05) on GRFs, propulsive and vertical forces increased with increasing speed. An independent t-test also showed significant differences (p < 0.05) in vertical and anterior-posterior GRFs at all running speeds, specifically, female runners demonstrated higher propulsive and vertical forces than males during the late stance phase of running. Pearson correlation and stepwise multiple linear regression showed significant correlations between running speed and the GRF variables. Discussion: These findings suggest that female runners require more effort to keep the same speed as male runners. This study may provide valuable insights into the underlying biomechanical factors of the movement patterns at GRFs during running.

Clustering analysis across different speeds reveals two distinct running techniques with no differences in running economy

Establishing the links between running technique and economy remains elusive due to high inter-individual variability. Clustering runners by technique may enable tailored training recommendations, yet it is unclear if different techniques are equally economical and whether clusters are speed-dependent. This study aimed to identify clusters of runners based on technique and to compare cluster kinematics and running economy. Additionally, we examined the agreement of clustering partitions of the same runners at different speeds. Trunk and lower-body kinematics were captured from 84 trained runners at different speeds on a treadmill. We used Principal Component Analysis for dimensionality reduction and agglomerative hierarchical clustering to identify groups of runners with a similar technique, and we evaluated cluster agreement across speeds. Clustering runners at different speeds independently produced different partitions, suggesting single speed clustering can fail to capture the full speed profile of a runner. The two clusters identified using data from the whole range of speeds showed differences in pelvis tilt and duty factor. In agreement with self-optimisation theories, there were no differences in running economy, and no differences in participants' characteristics between clusters. Considering inter-individual technique variability may enhance the efficacy of training designs as opposed to 'one size fits all' approaches.

Neuromuscular and trunk control mediate factors associated with injury in fatigued runners

This study aimed to determine how fatigue affects factors associated with injury, neuromuscular activity, and control in recreational runners. Previously identified injury risk factors were defined as peak vertical instantaneous loading rates (pVILR) for tibial stress fracture (TSF) and peak hip adduction (pHADD) for patellofemoral pain syndrome and iliotibial band syndrome. Kinematics, kinetics, and electromyography data were collected from 11 recreational runners throughout a fatiguing run. Three trials were collected in the first and final minutes of the run. Coactivation was quantified about the knee and ankle for the entire stance phase and anticipatory, weight acceptance (WA), and propulsion sub-phases of stance. Trunk control was quantified by the peak mediolateral lean, peak forward lean, and flexion range of motion (ROM). There were significant increases in pHADD and pVILR when fatigued. Significant decreases in coactivation around the knee were found over the entire stance phase, in the anticipatory phase, and WA phase. Coactivation decreased about the ankle during WA. Lateral trunk lean significantly increased when fatigued, but no significant changes were found in flexion ROM or lean. Mediation analyses showed changes in ankle coactivation during WA, and lateral trunk lean are significant influences on pVILR, a measure associated with TSF. Fatigue-induced adaptations of decreasing ankle coactivation during WA and increased lateral trunk lean may increase the likelihood of TSF. In this study, a fatiguing run influenced changes in control in recreational runners. Further investigation of causal fatigue-induced injuries is necessary to better understand the effects of coactivation and trunk control.

Evaluation of the optimal number of steps to obtain reliable running spatio-temporal parameters and their variability

BACKGROUND

Spatio-temporal running parameters and their variability help to determine a runner's running style. However, determining whether a change is due to the measurement or to a specific condition such as an injury is a matter of debate, as no recommendation on the number of steps required to obtain reliable assessments exists.

RESEARCH QUESTION

What is the optimal number of steps required to measure different spatio-temporal parameters and study their variability at different running speeds?

METHODS

Twenty-five runners performed three experimental sessions of three bouts of treadmill running at 8, 10 and 12 km/h separated by 24 h. We measured cadence, stride, step, contact and flight time. We calculated the duty factor and the leg stiffness index (Kleg). Mean spatio-temporal parameters and linear (coefficient of variation, standard deviation) and non-linear (Higuchi fractal index, α1 coefficient of detrended fluctuation analysis) analyses were computed for different numbers of steps. Relative reliability was determined using the intraclass coefficient correlation. The minimal number of steps which present a good reliability level was considered as the optimal number of steps for measurement. Absolute reliability was assessed by calculating minimal detectable change.

RESULTS

To assess the mean values of spatio-temporal running parameters, between 16 and 150 steps were required. We were unable to obtain an optimal number of steps for cadence, stride and step-time variabilities for all speeds. For the linear analyses, we deduced the optimal number of steps for Kleg and the contact time (around 350 steps). Non-linear analyses measurements required between 350 and 540 steps, depending on the parameter.

SIGNIFICANCE

Researchers and clinicians should optimize experimental conditions (number of steps and running speed) depending on the parameter or the variability analysis targeted. Future studies must use absolute reliability metrics to report changes in response to a specific condition with no bias due to measurement error.

Are Gait Patterns during In-Lab Running Representative of Gait Patterns during Real-World Training? An Experimental Study

Biomechanical assessments of running typically take place inside motion capture laboratories. However, it is unclear whether data from these in-lab gait assessments are representative of gait during real-world running. This study sought to test how well real-world gait patterns are represented by in-lab gait data in two cohorts of runners equipped with consumer-grade wearable sensors measuring speed, step length, vertical oscillation, stance time, and leg stiffness. Cohort 1 (N = 49) completed an in-lab treadmill run plus five real-world runs of self-selected distances on self-selected courses. Cohort 2 (N = 19) completed a 2.4 km outdoor run on a known course plus five real-world runs of self-selected distances on self-selected courses. The degree to which in-lab gait reflected real-world gait was quantified using univariate overlap and multivariate depth overlap statistics, both for all real-world running and for real-world running on flat, straight segments only. When comparing in-lab and real-world data from the same subject, univariate overlap ranged from 65.7% (leg stiffness) to 95.2% (speed). When considering all gait metrics together, only 32.5% of real-world data were well-represented by in-lab data from the same subject. Pooling in-lab gait data across multiple subjects led to greater distributional overlap between in-lab and real-world data (depth overlap 89.3-90.3%) due to the broader variability in gait seen across (as opposed to within) subjects. Stratifying real-world running to only include flat, straight segments did not meaningfully increase the overlap between in-lab and real-world running (changes of <1%). Individual gait patterns during real-world running, as characterized by consumer-grade wearable sensors, are not well-represented by the same runner's in-lab data. Researchers and clinicians should consider "borrowing" information from a pool of many runners to predict individual gait behavior when using biomechanical data to make clinical or sports performance decisions.

One-dimension statistical parametric mapping in lower limb biomechanical analysis: A systematic scoping review

BACKGROUND

Biomechanics significantly impacts sports performance and injury prevention. Traditional methods like discrete point analysis simplify continuous kinetic and kinematic data, while one-dimensional Statistical Parametric Mapping (spm1d) evaluates entire movement curves. Nevertheless, spm1d's application in sports and injury research is limited. As no systematic review exists, we conducted a scoping systematic review, synthesizing the current applications of spm1d across various populations, activities, and injuries. This review concludes by identifying gaps in the literature and suggesting areas for future research.

RESEARCH QUESTION

What research exists using spm1d in sports biomechanics, focusing on the lower limbs, in what populations, and what are the current research gaps?

METHODS

We searched PubMed, Embase, Web of Science, and ProQuest databases for the following search string: "(((knee) OR (hip)) OR (ankle)) OR (foot) OR (feet) AND (statistical parametric mapping)". English peer-reviewed studies assessing lower limb kinetics or kinematics in different sports or sports-related injuries were included. Reviews, meta-analyses, conference abstracts, and grey literature were excluded.

RESULTS

Our search yielded 165 papers published since 2012. Among these, 112 examined healthy individuals (67 %), and 53 focused on injured populations (33 %). Running (n = 45), cutting (n = 25), and jumping/landing (n = 18) were the most common activities. The predominant injuries were anterior cruciate ligament rupture (n = 21), chronic ankle instability (n = 18), and hip-related pain (n = 9). The main research gaps included the unbalanced populations, underrepresentation of common sports and sport-related injuries, gender inequality, a lack of studies in non-laboratory settings, a lack of studies on varied sports gear, and a lack of reporting standardization.

SIGNIFICANCE

This review spotlights crucial gaps in spm1d research within sports biomechanics. Key issues include a lack of studies beyond laboratory settings, underrepresentation of various sports and injuries, and gender disparities in research populations. Addressing these gaps can significantly enhance the application of spm1d in sports performance, injury analysis, and rehabilitation.

Validity and reliability of two-dimensional video-based assessment to measure joint angles during running: A systematic review and meta-analysis

Two-dimensional video analysis systems (2DVAS) are commonly used by clinicians and researchers to determine angles during running. The aim of this systematic review (PROSPERO: CRD42022322798) was to synthesize the literature on the criterion validity and reliability of 2DVAS for measuring angles during running compared to three-dimensional motion analysis systems (3DMAS). We searched for articles on MEDLINE/Pubmed, EMBASE, SciELO, and LILACS up to October/2022. We included studies that evaluated the validity of 2DVAS (when compared to 3DMAS) and/or the reliability of 2DVAS measurements of lower limb and trunk angles during running. Qualitative and quantitative analyses were performed. Seven hundred and five studies were found and 17 were included. Ten studies analysed criterion validity between 2DVAS and 3DMAS and the results ranged from poor to excellent, with most of the parameters assessed presenting poor or moderate validity. Inter-rater reliability of 2DVAS was assessed in nine studies and most of the parameters investigated had good to excellent reliability. Intra-rater reliability (between-day processing) of angular running parameters - investigated in ten studies - was considered excellent for most of the parameters analysed. Inter-session reliability was assessed in three studies and was defined as good or excellent for most of the variables assessed. 2DVAS is a reliable method for measuring joint angles during running. However, the validity of 2DVAS compared to 3DMAS ranges from low to moderate for most running parameters. Therefore, based on the available evidence, caution should be taken when applying 2DVAS, particularly for frontal and transverse plane angles.

Asymmetries of foot strike patterns during running in high-level female and male soccer players

BACKROUND

Foot strike pattern (FSP) is defined by the way the foot makes initial ground contact and is influenced by intrinsic and extrinsic factors. This study investigated the effect of running speed on asymmetries of FSP.

METHODS

Seventeen female and nineteen male soccer players performed an incremental running test on an instrumented treadmill starting at 2.0 m/s until complete exhaustion. Force plate data were used to categorize foot strikes into rearfoot (RFS) and non-rearfoot strikes. Additionally, peak vertical ground reaction force (peakGRF) and stride time were calculated. The symmetry index (SI) was used to quantify lateral asymmetries between legs.

RESULTS

The SI indicated asymmetries of the rate of RFS (%RFS) of approximately 30% at slow running speed which decreased to 4.4% during faster running speed (p = 0.001). There were minor asymmetries in peakGRF and stride time at each running stage. Running speed influenced %RFS (p < 0.001), peakGRF (p < 0.001) and stride time (p < 0.001). Significant interaction effects between running speed and sex were shown for %RFS (p = 0.033), peakGRF (p < 0.001) and stride time (p = 0.041).

CONCLUSION

FSP of soccer players are asymmetric at slower running speed, but symmetry increases with increasing speed. Future studies should consider that FSP are non-stationary and influenced by running speed but also differ between legs.

The "impacts cause injury" hypothesis: Running in circles or making new strides?

Some of the earliest biomechanics research focused on running and the ground reaction forces generated with each step. Research in running gait accelerated in the 1970's as the growing popularity in running increased attention to the musculoskeletal injuries sustained by runners. Despite decades of high-quality research, running remains the most common cause of exercise-related musculoskeletal injuries and rates of overuse running-related injuries (RRI) have not appreciably declined since the research began. One leading area of running gait research focuses on discrete variables derived from the vertical ground reaction force, such as the vertical loading rate. Across sub-disciplines of running gait research, vertical loading rate is often discussed as the primary and undisputed variable associated with RRI despite only low to moderate evidence that retrospectively or prospectively injured runners generate greater vertical loading rates than uninjured counterparts. The central thesis of this review is that relying on vertical loading rate is insufficient to establish causal mechanisms for RRI etiology. To present this argument, this review examines the history of the 'impacts cause injury' hypothesis, including a historical look at ground reaction forces in human running and the research from which this hypothesis was generated. Additionally, a synthesis of studies that have tested the hypothesis is provided and recommendations for future research are discussed. Although it is premature to reject or support the 'impacts cause injury' hypothesis, new knowledge of biomechanical risk factors for RRI will remain concealed until research departs from the current path or adopts new approaches to previous paradigms.

Dynamic postural control in injured collegiate cross-country runners is not associated with running-related injury

BACKGROUND

Biomechanical factors have been associated with running-related injury, but associations are unclear. Dynamic postural stability may be a factor related to injury that has not been studied extensively.

RESEARCH QUESTION

Does dynamic postural control differ in those with a history of running-related injury or those who go on to sustain a running-related injury?

METHODS

Sixty-five (45 injured; 20 uninjured) and fifty-eight (13 injured; 45 uninjured) collegiate cross-country runners were available for our retrospective and prospective analyses. Time to stabilization and dynamic postural stability index were collected during two separate jump landing tasks (forward and lateral direction) for each leg. Retrospective injury was tabulated by a running history survey. Prospective injuries were recorded by a licensed athletic trainer during the competitive season. Differences in postural stability were compared between injured and uninjured groups and between limbs using two-way ANOVA's. An overall group by leg comparison was completed for each task.

RESULTS

The non-dominant limb demonstrated better postural stability indices regardless of injury history. An interaction was observed between limbs and history of injury for the anterior-posterior time to stabilization for the lateral task. The non-dominant limb demonstrated better medio-lateral postural stability indices and time to stabilization during the lateral task, regardless of prospective injury.

SIGNIFICANCE

Dynamic postural stability was reduced in the dominant limb, but no clear differences were seen between injured and uninjured runners. This suggests dynamic postural stability may be altered in individuals with a history of a running-related injury, but no relationship to subsequent injury was substantiated. Further work is needed to understand how dynamic postural stability may be related to running-related injury.

Kinematic and muscle force asymmetry in healthy runners: How do different methods measure up?

BACKGROUND

Comparing the performance of one leg to another is a common means of assessing running gait to help inform clinical management strategies. Various methods are employed to quantify asymmetries between limbs. However, limited data is available describing the amount of asymmetry that may be expected during running and no index has been identified as preferable for making a clinical determination of asymmetry. Therefore, this study aimed to describe amounts of asymmetry in collegiate cross-country runners and compare different methods of calculating asymmetry.

RESEARCH QUESTION

What can be expected as a normal amount of asymmetry in biomechanical variables in healthy runners when using different indices to quantify limb symmetry?

METHODS

Sixty-three (29 male and 34 female) runners participated. Running mechanics were assessed during overground running using 3D motion capture and a musculoskeletal model using static optimization to estimate muscle forces. Independent t-tests were utilized to determine statistical differences in variables between legs. Different methods of quantifying asymmetry were then compared to statistical differences between limbs to determine cut-off values and the sensitivity and specificity of each method.

RESULTS

A large portion of runners demonstrated asymmetry during running. Kinematic variables can be expected to have small differences (2-3 degrees) between limbs while muscle forces may show greater amounts of asymmetry. The sensitivities and specificities for each method of calculating asymmetry were similar, however, different methods led to different cut-off values for each variable investigated.

SIGNIFICANCE

Asymmetry can be expected between limbs during running. However, when assessing asymmetry, practitioners should consider the joint, variable, and method of calculating asymmetry when determining differences between limbs.

Differences in kinetic variables between injured and uninjured rearfoot runners: A hierarchical cluster analysis

Running is a popular form of physical activity with a high incidence of running-related injuries. However, the etiology of running-related injuries remains elusive, possibly due to the heterogeneity of movement patterns. The purpose of this study was to investigate whether different clusters existed within a large group of injured and uninjured runners based on their kinetic gait patterns. A sample of 134 injured and uninjured runners were acquired from an existing database and 12 discrete kinetic and spatiotemporal variables which are commonly associated with running injuries were extracted from the ground reaction force waveforms. A principal components analysis followed by an unsupervised hierarchical cluster analysis was performed. The results revealed two distinct clusters of runners which were not associated with injury status (OR = 1.14 [0.57, 2.30], χ²  = 0.143, p = 0.706) or sex (OR = 1.72 [0.85, 3.49], χ²  = 2.3258, p = 0.127). These results suggest that while there appeared to be evidence for two distinct clusters within a large sample of injured and uninjured runners, there is no association between the kinetic variables and running related injuries.

Between-day reliability and minimum detectable change of the Conventional Gait Model 2 and Plug-in Gait Model during running

BACKGROUND

The Plug-in Gait model (PiG) is commonly used in 3D motion analysis but has limited reliability. Although an improved version of PiG has been developed, called the Conventional Gait Model 2 (CGM2), there is limited evidence on its between-day reliability for running.

RESEARCH QUESTION

What is the between-day intraclass correlation coefficient (ICC3,k) and minimum detectable change (MDC) of lower limb kinematics and kinetics for CGM2 during running and does reliability differ between CGM2 and PiG.

METHODS

Twenty-three healthy participants performed running at a comfortable speed in two identical test sessions at least 5 days apart. Lower limb kinematic and kinetic data in the three planes of motion were calculated using CGM2 and PiG. The ICC and MDC were calculated for the kinematic and kinetic parameters at initial contact and peak during the stance phase of running.

RESULTS

CGM2 kinematics showed good-to-excellent reliability (ICC: 0.75-0.93), except for hip extension and ankle internal rotation, and less than 5° MDC (1.8°-4.9°) of the coronal and sagittal planes, except for hip extension. PiG showed poor-to-moderate reliability (ICC: -0.15 to 0.72) in the coronal and transverse planes and greater than 5° MDC (5.0°-21.8°), except for knee extension, adduction, and ankle dorsiflexion. CGM2 showed good-to-excellent reliability for peak kinetics (ICC: 0.75-0.97), except for hip internal rotation and knee extension. The ICC and MDC were higher for CGM2 than PiG, with significant differences in the coronal plane of the hip and knee joints and transverse plane of the hip joint in kinematics and in the sagittal and coronal plane of the hip and knee joints in kinetics.

SIGNIFICANCE

The between-day reliability of CGM2 was mostly good to excellent for lower limb kinematics and kinetics during running. We believe that CGM2 can more accurately assess kinematic differences between the coronal and transverse planes than the PiG.

Quantifying and correcting for speed and stride frequency effects on running mechanics in fatiguing outdoor running

Measuring impact-related quantities in running is of interest to improve the running technique. Many quantities are typically measured in a controlled laboratory setting, even though most runners run in uncontrolled outdoor environments. While monitoring running mechanics in an uncontrolled environment, a decrease in speed or stride frequency can mask fatigue-related changes in running mechanics. Hence, this study aimed to quantify and correct the subject-specific effects of running speed and stride frequency on changes in impact-related running mechanics during a fatiguing outdoor run. Seven runners ran a competitive marathon while peak tibial acceleration and knee angles were measured with inertial measurement units. Running speed was measured through sports watches. Median values over segments of 25 strides throughout the marathon were computed and used to create subject-specific multiple linear regression models. These models predicted peak tibial acceleration, knee angles at initial contact, and maximum stance phase knee flexion based on running speed and stride frequency. Data were corrected for individual speed and stride frequency effects during the marathon. The speed and stride frequency corrected and uncorrected data were divided into ten stages to investigate the effect of marathon stage on mechanical quantities. This study showed that running speed and stride frequency explained, on average, 20%-30% of the variance in peak tibial acceleration, knee angles at initial contact, and maximum stance phase knee angles while running in an uncontrolled setting. Regression coefficients for speed and stride frequency varied strongly between subjects. Speed and stride frequency corrected peak tibial acceleration, and maximum stance phase knee flexion increased throughout the marathon. At the same time, uncorrected maximum stance phase knee angles showed no significant differences between marathon stages due to a decrease in running speed. Hence, subject-specific effects of changes in speed and stride frequency influence the interpretation of running mechanics and are relevant when monitoring, or comparing the gait pattern between runs in uncontrolled environments.

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.

Clinical Application of Gait Retraining in the Injured Runner

Despite its positive influence on physical and mental wellbeing, running is associated with a high incidence of musculoskeletal injury. Potential modifiable risk factors for running-related injury have been identified, including running biomechanics. Gait retraining is used to address these biomechanical risk factors in injured runners. While recent systematic reviews of biomechanical risk factors for running-related injury and gait retraining have been conducted, there is a lack of information surrounding the translation of gait retraining for injured runners into clinical settings. Gait retraining studies in patients with patellofemoral pain syndrome have shown a decrease in pain and increase in functionality through increasing cadence, decreasing hip adduction, transitioning to a non-rearfoot strike pattern, increasing forward trunk lean, or a combination of some of these techniques. This literature suggests that gait retraining could be applied to the treatment of other injuries in runners, although there is limited evidence to support this specific to other running-related injuries. Components of successful gait retraining to treat injured runners with running-related injuries are presented.

The effect of sex, stature, and limb length on the preferred walk-to-run transition speed

BACKGROUND

The preferred walk-to-run transition speed (PTS) for healthy adults is approximately 2 m∙s^-1, however, PTS is influenced by anthropometric factors. Yet despite known sex differences in anthropometrics, studies have reported no sex differences in PTS.

RESEARCH QUESTION

Do stature and limb length affect PTS in the same way for both male and female healthy adults?

METHODS

Thirty-seven (19 female) non-injured adults volunteered for this study. Participants completed a walk-to-run transition protocol, where the treadmill speed was increased from 1.2 m∙s^-1 to 2.2 m∙s^-1, in increments of 0.1 m∙s^-1 every two minutes. An independent t-test compared PTS between sexes. Multiple regression analysis determined the effect of sex and stature and sex and limb length on PTS.

RESULTS

Female participants transitioned at a lower PTS than male participants (1.8 (0.2) m∙s^-1 versus 1.9 (0.1) m∙s^-1; p ≤ 0.026). Sex and stature explained 19% of the variance in PTS, while sex and limb length explained 21% of the variance. Including interactions increased the variance explained by 23% and 2% for sex and stature and sex and limb length, respectively. The significant interaction between sex and stature showed PTS was inversely proportional to stature for male participants but directly proportional for female participants.

SIGNIFICANCE

These findings suggest that the extent to which stature and limb length influence the preferred transition speed may differ between sexes.

Are models of plantar heel pain suitable for competitive runners? A narrative review

Background

Plantar heel pain (PHP), or plantar fasciopathy, is a common condition in active and sedentary populations, contributing to short- and long-term reductions in quality of life. The condition's aetiology and pathophysiology are the subjects of a significant body of research. However, much of this research has been conducted with sedentary participants, and comparatively little research exists in a population of highly-trained athletes focused on performance outcomes. Models for PHP and proposed mechanisms, such as high body mass index or systemic disease, are mostly absent from an athletic population. Even less is known about the origins of pain in PHP. Pain is believed to be a complex multifactorial process and may be experienced differently by sedentary and highly active populations, particularly endurance athletes. Consequently, conservative through to surgical treatment for athletes is informed by literature for a different population, potentially hindering treatment outcomes.

Aims

The aim of this review, therefore, is to summarise what is known about PHP in athletic populations and propose potential directions for future research.

Methods

Embase, PubMed, and Scopus using MeSH search terms for PHP and competitive sport and common synonyms.

Discussion

Two explanatory models for PHP were found. These primarily propose mechanical factors for PHP. It remains unclear how gait, body composition, and psychological factors may differ in an athletic population with and without PHP. Therefore, research in these three areas is needed to inform clinical and training interventions for this population.

A qualitative examination of the factors affecting the adoption of injury focused wearable technologies in recreational runners

Purpose

Understanding the perceived efficacy and ease of use of technologies will influence initial adoption and sustained utilization. The objectives of this study were to determine the metrics deemed important by runners for monitoring running-related injury (RRI) risk, and identify the facilitators and barriers to their use of injury focused wearable technologies.

Methods

A qualitative focus group study was undertaken. Nine semi-structured focus groups with male (n = 13) and female (n = 14) recreational runners took place. Focus groups were audio and video recorded, and transcribed verbatim. Transcripts were thematically analysed. A critical friend approach was taken to data coding, and multiple methods of trustworthiness were executed.

Results

Excessive loading and inadequate recovery were deemed the most important risk factors to monitor for RRI risk. Other important factors included training activities, injury status and history, and running technique. The location and method of attachment of a wearable device, the design of a smartphone application, and receiving useful injury-related information will affect recreational runners’ adoption of injury focused technologies.

Conclusions

Overtraining, training-related and individual-related risk factors are essential metrics that need to be monitored for RRI risk. RRI apps should include the metrics deemed important by runners, once there is supporting evidence-based research. The difficulty and/or ease of use of a device, and receiving useful feedback will influence the adoption of injury focused running technologies. There is a clear willingness from recreational runners to adopt injury focused wearable technologies whilst running.

A Comparison of a Novel Stretchable Smart Patch for Measuring Runner’s Step Rates with Existing Measuring Technologies

A novel wearable smart patch can monitor various aspects of physical activity, including the dynamics of running, but like any new device developed for such applications, it must first be tested for validity. Here, we compare the step rate while running in place as measured by this smart patch to the corresponding values obtained utilizing ‘‘gold standard’’ MEMS accelerometers in combination with bilateral force plates equipped with HBM load cells, as well as the values provided by a three-dimensional motion capture system and the Garmin Dynamics Running Pod. The 15 healthy, physically active volunteers (age = 23 ± 3 years; body mass = 74 ± 17 kg, height = 176 ± 10 cm) completed three consecutive 20-s bouts of running in place, starting at low, followed by medium, and finally at high intensity, all self-chosen. Our major findings are that the rates of running in place provided by all four systems were valid, with the notable exception of the fast step rate as measured by the Garmin Running Pod. The lowest mean bias and LoA for these measurements at all rates were associated consistently with the smart patch.

Biomechanics of running: A special reference to the comparisons of wearing boots and running shoes

Boots are often used in sports, occupations, and rehabilitation. However, there are few studies on the biomechanical alterations after wearing boots. The current study aimed to compare the effects of running shoes and boots on running biomechanics. Kinematics and ground reaction forces were recorded from 17 healthy males during running at 3.3 m/s with shoe and boot conditions. Temporal distance gait variables, ground reaction force components as well as lower limb joints angle, moment, and power were compared using Paired t-test and Statistical Parametric Mapping package for time-series analysis. Running with boots was associated with greater stride, step, flight, and swing times, greater flight length, and smaller cadence (p<0.05). The only effect of boots on lower limb joints kinematics during running was a reduction in ankle range of motion (p<0.05). Significantly greater hip flexor, abductor, and internal rotator moments, greater knee extensor and abductor moments, and ankle plantar flexor moments were observed at push-off phase of running as well as greater ankle dorsiflexor moment at early-stance in boot condition (p<0.05). Also, knee joint positive power was greater with a significant temporal shift in boot condition, suggesting a compensatory mechanism in response to limited ankle range of motion and the inability of the ankle joint to generate the required power. Our findings showed that running with boots is physically more demanding and is associated with a greater net contribution of muscles spanning hip and knee joints in order to generate more power and compensate for the ankle joint limitations, consequently, may increase the risk of both musculoskeletal injuries and degenerative joint diseases.

Running Footwear and Impact Peak Differences in Recreational Runners

Running is a physical activity and the investigation of its biomechanical aspects is crucial both to avoid injuries and enhance performance. Recreational runners may be liable to increased stress over the body, particularly to lower limb joints. This study investigates the different running patterns of recreational runners by analyzing characteristics of the footwear impact peak, spatiotemporal, and kinematic parameters among those that present with a peak impact and those that do not, with a 3D markerless system. Thirty recreational runners were divided into two groups: impact peak group (IP) (n = 16) and no impact peak group (n = 14) (n-IP). Kinematic and spatiotemporal parameters showed a large Cohen's d effect size between the groups. The mean hip flexion was IP 40.40° versus n-IP 32.30° (d = -0.82). Hip extension was IP 30.20° versus n-IP 27.70° (d = -0.58), and ankle dorsiflexion was IP 20.80°, versus n-IP 13.37° (d = -1.17). Stride length was IP 117.90 cm versus n-IP 105.50 cm (d = -0.84). Steps per minute was IP group 170 spm, versus n-IP 163 spm (d = -0.51). The heel-to-toe drop was mainly 10-12 mm for the IP group and 4-6 mm for the n-IP group. Recreational runners whose hip extension is around 40°, ankle dorsiflexion around 20°, and initial foot contact around 14°, may be predisposed to the presence of an impact peak.

A machine learning approach to identify risk factors for running-related injuries: study protocol for a prospective longitudinal cohort trial

BACKGROUND

Running is a very popular sport among both recreational and competitive athletes. However, participating in running is associated with a comparably high risk of sustaining an exercise-related injury. Due to the often multifactorial and individual reasons for running injuries, a shift in thinking is required to account for the dynamic process of the various risk factors. Therefore, a machine learning approach will be used to comprehensively analyze biomechanical, biological, and loading parameters in order to identify risk factors and to detect risk patterns in runners.

METHODS

The prospective longitudinal cohort study will include competitive adult athletes, running at least 20 km per week and being free of injuries three months before the start of the study. At baseline and the end of the study period, subjective questionnaires (demographics, injury history, sports participation, menstruation, medication, psychology), biomechanical measures (e.g., stride length, cadence, kinematics, kinetics, tibial shock, and tibial acceleration) and a medical examination (BMI, laboratory: blood count, creatinine, calcium, phosphate, parathyroid hormone, vitamin D, osteocalcin, bone-specific alkaline phosphatase, DPD cross-links) will be performed. During the study period (one season), continuous data collection will be performed for biomechanical parameters, injuries, internal and external load. Statistical analysis of the data is performed using machine learning (ML) methods. For this purpose, the correlation of the collected data to possible injuries is automatically learned by an ML model and from this, a ranking of the risk factors can be determined with the help of sensitivity analysis methods.

DISCUSSION

To achieve a comprehensive risk reduction of injuries in runners, a multifactorial and individual approach and analysis is necessary. Recently, the use of ML processes for the analysis of risk factors in sports was discussed and positive results have been published. This study will be the first prospective longitudinal cohort study in runners to investigate the association of biomechanical, bone health, and loading parameters as well as injuries via ML models. The results may help to predict the risk of sustaining an injury and give way for new analysis methods that may also be transferred to other sports.

TRIAL REGISTRATION

DRKS00026904 (German Clinical Trial Register DKRS), date of registration 18.10.2021.

Running Injury Paradigms and Their Influence on Footwear Design Features and Runner Assessment Methods: A Focused Review to Advance Evidence-Based Practice for Running Medicine Clinicians

Many runners seek health professional advice regarding footwear recommendations to reduce injury risk. Unfortunately, many clinicians, as well as runners, have ideas about how to select running footwear that are not scientifically supported. This is likely because much of the research on running footwear has not been highly accessible outside of the technical footwear research circle. Therefore, the purpose of this narrative review is to update clinical readers on the state of the science for assessing runners and recommending running footwear that facilitate the goals of the runner. We begin with a review of basic footwear construction and the features thought to influence biomechanics relevant to the running medicine practitioner. Subsequently, we review the four main paradigms that have driven footwear design and recommendation with respect to injury risk reduction: Pronation Control, Impact Force Modification, Habitual Joint (Motion) Path, and Comfort Filter. We find that evidence in support of any paradigm is generally limited. In the absence of a clearly supported paradigm, we propose that in general clinicians should recommend footwear that is lightweight, comfortable, and has minimal pronation control technology. We further encourage clinicians to arm themselves with the basic understanding of the known effects of specific footwear features on biomechanics in order to better recommend footwear on a patient-by-patient basis.

Biomechanical and Musculoskeletal Measurements as Risk Factors for Running-Related Injury in Non-elite Runners: A Systematic Review and Meta-analysis of Prospective Studies

BACKGROUND

Running-related injury (RRI) is highly prevalent among recreational runners and is a key barrier to participation. Atypical lower limb alignment and mechanical function have been proposed to play a role in development of lower extremity injury. The purpose of this study was to investigate relationships between incidence of running-related injury (RRI) in non-elite runners with biomechanical and musculoskeletal variables.

METHODS

A systematic review and meta-analysis of prospective studies. Published research indexed in MEDLINE, EMBASE, CINAHL, SPORTDiscus, AMED, and The Cochrane library until 13th January 2021, grey literature, and reference lists of included studies were screened to identify prospective studies of non-elite adult runners that measured a relationship between biomechanical or musculoskeletal measures and incidence of RRI.

RESULTS

Thirty studies (3404 runners), testing over 100 discrete biomechanical and musculoskeletal risk factors for RRI, were included. Nineteen studies were pooled in twenty-five separate meta-analyses. Meta-analysis of four studies detected significantly less knee extension strength among runners who developed a RRI (SMD - 0.19, 95% CI - 0.36 to - 0.02, p = 0.03), though this may not be clinically important. A meta-analysis of two studies detected significantly lower hip adduction velocity among runners who developed a RRI (MD - 12.80, 95% CI - 25.22 to - 0.38, p = 0.04). Remaining meta-analyses found no significant relationship between biomechanical or musculoskeletal variables and RRI.

CONCLUSION

This systematic review and meta-analysis found the currently available literature does not generally support biomechanical or musculoskeletal measures as risk factors for RRI in non-elite runners. While meta-analysis findings for knee extension strength and hip adduction velocity as risk factors for RRI were statistically significant, the associated trivial to small effects sizes suggest these findings should be treated with caution. Until further evidence emerges, recommendations for injury prevention in non-elite runners cannot be made based on biomechanical and musculoskeletal measurements alone.

Internet Survey of Risk Factors Associated With Training and Competition in Dogs Competing in Agility Competitions

Objective: To describe risk factors associated with training and competition in relation to frequency and severity of injuries experienced by agility dogs.

Procedures: An internet-based survey collected data on competition level variables and training level variables. The primary outcome was history of any injury and a secondary outcome considered history of severe injury (injury lasting > 3 months). Logistic regression was used to estimate associations and final models were obtained via backward selection to identify the strongest associations within variables.

Results: There were 4,197 dogs included in this analysis. Injury was reported for 1,737 (41.4%) dogs and severe injury was reported for 629 (15.0%). In the model with competition level factors, jumping 4” (OR: 1.50) or 2–4” (OR: 1.31) over shoulder height compared to jumping 0–2” lower and competing at national events was associated with increased injury risk, while competing 6+ times on rubber matting was associated with lower risk (OR: 0.62). Training level variables associated with injury risk were age starting jump, teeter, and weave training, with the highest risk observed for dogs starting jump training between 3 and 18 months but starting weave and teeter training after 18 months of age.

Conclusion and Clinical Relevance: Many variables thought to be associated with injury risk were not significant in the final model. Starting jump training at an earlier age was associated with greater risk of injury relative to starting after 18 months. It is possible that the high impact of jump training before skeletal maturity may increase the risk of injuries or musculoskeletal conditions. The increased risk of injury in dogs that jump 2–4, or 4+ inches higher than shoulder height may be due to increased biomechanical forces during takeoff and landing. Faster dogs may be at higher risk of injury; handlers planning competition around big events or competing at the national level are likely to have faster dogs, and may be less likely to compete on rubber matting. These data provide valuable current insight into the possible effects that training and competition variables may have on injury risk in agility dogs.

The Use of a Single Trunk-Mounted Accelerometer to Detect Changes in Center of Mass Motion Linked to Lower-Leg Overuse Injuries: A Prospective Study

Movement dynamics during running was previously characterized using a trunk-mounted accelerometer, and were associated with a history of overuse injuries. However, it remains unknown if these measures are also linked to the development of overuse injuries. The aim of this study was therefore to determine how movement dynamics alter in response to fatigue, and the possible link with developing lower-leg overuse injuries during a six-month follow-up period. Two hundred and eight movement science university students completed a 12-min all-out run while wearing a trunk-mounted accelerometer. Dynamic stability, dynamic loading and spatiotemporal measures were extracted from the accelerometer. Participants sustaining an injury within the 6-month period demonstrated significantly higher RMS ratio values in the vertical direction and lower RMS ratio values in the anteroposterior direction, and lower impact acceleration values in the anteroposterior direction in an unfatigued state compared to the uninjured group. They also demonstrated an increase in dynamic loading in the horizontal plane during the run. In addition, with running fatigue both groups exhibited changes in dynamic stability and loading measures. These results show the potential of using a single trunk-mounted accelerometer to detect changes in movement dynamics that are linked to lower-leg overuse injuries.

The Epidemiology, Risk Factors, and Nonsurgical Treatment of Injuries Related to Endurance Running

ABSTRACT

Running is a popular form of exercise that is easily accessible to various populations; endurance running, defined as distances beyond 5 km, continues to grow within the sport. Endurance running-related injuries are common in the lower extremities and are primarily overuse related. A multitude of risk factors for injury exist, including extrinsic factors, such as running distance and frequency, and intrinsic factors, such as biomechanics and nutrition status. Training and rehabilitation techniques vary with a general focus on strengthening and gradual increase in activity, but evidence is mixed, and it is difficult to generalize programs across different running populations. Management of specific running groups, including youth runners, is an area in which additional research is needed. New treatments, such as orthobiologics and wearable technology, have promising potential to optimize performance and recovery and minimize injury. However, they need to be further evaluated with high-quality studies.

Effect of Increasing Running Cadence on Peak Impact Force in an Outdoor Environment

BACKGROUND

An estimated 56% of recreational runners sustain a running-related injury related to the high impact forces in running. Increasing step frequency (cadence) while maintaining a consistent speed has been shown to be an effective way to lower impact forces which may reduce injury risk.

PURPOSE

To examine effects of increased cadence on peak impact force during running in an outdoor setting. It was hypothesized that as cadence increases, peak force would decrease.

STUDY DESIGN

Repeated measures, quasi-experimental.

METHODS

Peak force and cadence measurements were collected from 15 recreational runners (8 females, 7 males) during two 2.4-mile outdoor runs. Peak force was measured using an insole-based load measuring device. Baseline session run was completed at participant's naturally preferred cadence and cadence session run was completed at a cadence targeted to be 10% greater than baseline. Pace was monitored with a GPS watch. Cadence was cued by an auditory metronome and measured with both GPS watch and insoles. Repeated-measures ANOVA's examined the differences in average peak force, GPS-reported cadence, and insole-reported cadence between mile 1 and mile 2, and across the two cadence conditions.

RESULTS

Cadence differences of 7.3% were observed between baseline and cadence sessions (p<0.001). A concurrent decrease in average peak force of 5.6% was demonstrated during the cadence run (p<0.05). Average cadences measured by GPS watch and insoles were found to be the same at both baseline (p=0.096) and during cadence (p=0.352) sessions.

CONCLUSION

Increasing cadence by an average of 7% in an outdoor setting resulted in a decrease in peak force at two different time points during a 2.4-mile run. Furthermore, using a metronome for in-field cadence manipulation led to a change in cadence. This suggests that a metronome may be an effective tool to manipulate cadence for the purpose of decreasing peak impact force in an outdoor setting.

LEVEL OF EVIDENCE

3b.

Performance goals of runners are associated with the occurrence of running-related injuries

OBJECTIVE

The aim of this study was to evaluate the relationship between running performance goals and running-related injuries (RRIs).

DESIGN

Retrospective cross-sectional study.

SETTING

A total of 970 recreational runners filled in an online questionnaire to collect data on personal characteristics, their running activities, RRIs, and running goals.

PARTICIPANTS

970 recreational runners, 1) without a running performance goal, who 2) trained to complete a certain distance, and who 3) trained to complete a certain distance and to participate in a specific running event.

MAIN OUTCOME MEASURES

RRI, defined as any physical complaint developed during running in the previous 12 months.

RESULTS

A statistically significant relationship was found between runners who trained for a specific running event and who also wanted to run a certain distance (OR 2.0, 95%CI 1.23-2.98) compared with runners without a running goal. (Hinder from a) Previous injury (OR 3.9, 95%CI 2.79-5.42), overweight (OR 1.6, 95%CI 1.10-2.21), and training for more than 22.5 h/year (OR 1.7, 95%CI 1.04-2.72 and OR 2.3, 95%CI 1.42-3.81) were also associated with RRIs.

CONCLUSION

Running to achieve running goals, specifically running to complete a certain distance and to participate in an event, is associated with the occurrence of an RRI.

Normative measures of hip strength and relation to previous injury in collegiate cross-country runners

CONTEXT

Running related injury occurs frequently in collegiate cross-country runners. Hip strength is one factor that may be important in the rehabilitation and training of cross-country runners. However, no normative values exist to inform these strategies.

OBJECTIVE

Establish normative values for hip abduction and external rotation isometric strength in collegiate cross-country runners and explore the association between strength and previous injury.

DESIGN

Mixed methods using descriptive epidemiology and retrospective cross-sectional designs.

SETTING

University Laboratory Patients or Other Participants: Eighty-two NCAA Division III cross-country runners (38 males, 44 females) participated in this study.

MAIN OUTCOME MEASURE(S)

Isometric hip strength and reported injury Results: Males demonstrated greater absolute hip strength than females. Measures of hip strength were not different between sexes when normalized to height and mass. Hip abduction asymmetry was associated with previous injury in males. A combination of at least one leg with hip abduction weakness and bilateral external rotation weakness was associated with previous injury in females.

CONCLUSIONS

Knowledge of normative values of hip strength may help inform rehabilitation strategies in collegiate cross-country runners. Males and females may demonstrate differing strength profiles following running related injury.

The effect of changing foot progression angle using real-time visual feedback on rearfoot eversion during running

Atypical rearfoot in/eversion may be an important risk factor for running-related injuries. Prominent interventions for atypical rearfoot eversion include foot orthoses, footwear, and taping but a modification derived from gait retraining to correct atypical rearfoot in/eversion is lacking. We aimed to investigate changes in rearfoot in/eversion, subtalar pronation, medial longitudinal arch angle, and selected lower limb joint biomechanics while performing toe-in/toe-out running using real-time visual feedback. Fifteen female runners participated in this study. Subjects performed toe-in/toe-out running using real-time visual feedback on foot progression angle, which was set ±5° from habitual foot progression angle. 3D kinematics of rearfoot in/eversion, subtalar supination/pronation, medial longitudinal arch angle, foot progression angle, hip flexion, ab/adduction and internal/external rotation, knee flexion, ankle dorsiflexion, and ankle power were analyzed. A repeated-measures ANOVA followed by pairwise comparisons was used to analyze changes between three conditions. Toe-in running compared to normal and toe-out running reduced peak rearfoot eversion (mean difference (MD) with normal = 2.1°; p<0.001, MD with toe-out = 3.5°; p<0.001), peak pronation (MD with normal = -2.0°; p<0.001, MD with toe-out = -3.4; p = <0.001), and peak medial longitudinal arch angle (MD with normal = -0.7°; p = 0.022, MD with toe-out = -0.9; p = 0.005). Toe-out running significantly increased these kinematic factors compared to normal and toe-in running. Toe-in running compared to normal running increased peak hip internal rotation (MD = 2.3; p<0.001), and reduced peak knee flexion (MD = 1.3; p = 0.014). Toe-out running compared to normal running reduced peak hip internal rotation (MD = 2.5; p<0.001), peak hip ab/adduction (MD = 2.5; p<0.001), peak knee flexion (MD = 1.5; p = 0.003), peak ankle dorsiflexion (MD = 1.6; p<0.001), and peak ankle power (MD = 1.3; p = 0.001). Runners were able to change their foot progression angle when receiving real-time visual feedback for foot progression angle. Toe-in/toe-out running altered rearfoot kinematics and medial longitudinal arch angle, therefore supporting the potential value of gait retraining focused on foot progression angle using real-time visual feedback when atypical rearfoot in/eversion needs to be modified. It should be considered that changes in foot progression angle when running is accompanied by changes in lower limb joint biomechanics.

Sex-Specific Differences in Running Injuries: A Systematic Review with Meta-Analysis and Meta-Regression

BACKGROUND

Running is a popular sport with high injury rates. Although risk factors have intensively been investigated, synthesized knowledge about the differences in injury rates of female and male runners is scarce.

OBJECTIVE

To systematically investigate the differences in injury rates and characteristics between female and male runners.

METHODS

Database searches (PubMed, Web of Science, PEDro, SPORTDiscus) were conducted according to PRISMA guidelines using the keywords "running AND injur*". Prospective studies reporting running related injury rates for both sexes were included. A random-effects meta-analysis was used to pool the risk ratios (RR) for the occurrence of injuries in female vs. male runners. Potential moderators (effect modifiers) were analysed using meta-regression.

RESULTS

After removal of duplicates, 12,215 articles were screened. Thirty-eight studies were included and the OR of 31 could be pooled in the quantitative analysis. The overall injury rate was 20.8 (95% CI 19.9-21.7) injuries per 100 female runners and 20.4 (95% CI 19.7-21.1) injuries per 100 male runners. Meta-analysis revealed no differences between sexes for overall injuries reported per 100 runners (RR 0.99, 95% CI 0.90-1.10, n = 24) and per hours or athlete exposure (RR 0.94, 95% CI 0.69-1.27, n = 6). Female sex was associated with a more frequent occurrence of bone stress injury (RR (for males) 0.52, 95% CI 0.36-0.76, n = 5) while male runners had higher risk for Achilles tendinopathies (RR 1. 86, 95% CI 1.25-2.79, n = 2). Meta-regression showed an association between a higher injury risk and competition distances of 10 km and shorter in female runners (RR 1.08, 95% CI 1.00-1.69).

CONCLUSION

Differences between female and male runners in specific injury diagnoses should be considered in the development of individualised and sex-specific prevention and rehabilitation strategies to manage running-related injuries.