Risk Of Running-related Injuries Research Articles

Comparison of Weekly Training Load and Acute: Chronic Workload Ratio Methods to Estimate Change in Training Load in Running.

Before examining the impact of training load on injury risk in runners, it is important to gain insight into the differences between methods that are used to measure change in training load. To investigate differences between 4 methods when calculating change in training load: (1) weekly training load; (2) acute : chronic workload ratio (ACWR), coupled rolling average (RA); (3) ACWR, uncoupled RA; (4) ACWR, exponentially weighted moving average (EWMA). Descriptive epidemiology study. This study is part of a randomized controlled trial on running injury prevention among recreational runners. Runners received a baseline questionnaire and a request to share global positioning system training data. Runners who registered for running events (distances 10-42.195 km) in the Netherlands. The primary outcome measure was the predefined significant increase in training load (weekly training loads ≥ 30% progression and ACWRs ≥ 1.5), based on training distance. Proportional Venn diagrams visualized the differences between the methods. A total of 430 participants (73.3% men; mean age = 44.3 ± 12.2 years) shared their global positioning system training data for a total of 22 839 training sessions. For the weekly training load, coupled RA, uncoupled RA, and EWMA method, respectively, 33.4% (95% CI = 32.8, 34.0), 16.2% (95% CI = 15.7, 16.6), 25.8% (95% CI = 25.3, 26.4), and 18.9% (95% CI = 18.4, 19.4) of the training sessions were classified as significant increases in training load. Of the training sessions with significant increases in training load, 43.0% from the weekly training load method were different than the coupled RA and EWMA methods. Training sessions with significant increases in training load based on the coupled RA method showed 100% overlap with the uncoupled RA and EWMA methods. The difference in the change in training load measured by weekly training load and ACWR methods was high. To validate an appropriate measure of change in training load in runners, future research on the association between training loads and running-related injury risk is needed.

Predictive Value of the KOJI AWARENESS Self-Evaluation System for Running Injuries in Elite Male Long-Distance Runners: A Prospective Cohort Study.

The KOJI AWARENESS (KA) test is a practical self-evaluation tool that assesses body movements and may help develop individual conditioning plans to improve movement function. However, the association between preseason KA scores and in-season injury occurrence remains unexplored. To investigate whether the KA self-screening test score can predict running-related injuries in elite long-distance runners. Cohort study; Level of evidence, 2. A total of 47 elite college male long-distance runners (age, 18-22 years) were enrolled in this study in June 2022. The participants underwent the KA self-screening test to assess preseason upper limb, core, and lower limb function. Running-related injuries with a training time loss of >3 weeks were tracked for 6 months during the season. The participants were divided into injury and noninjury groups, and between-group comparisons and receiver operating characteristic (ROC) curve analysis were used to determine the association between the KA scores and the injury incidence. Chi-square tests and risk ratios were calculated based on the cutoff value- and injury-based grouping. Among the runners, 10 (21.3%) sustained an injury. There were no significant differences in the demographic characteristics between the injury and noninjury groups. The injury group had significantly lower KA scores than the noninjury group (median, 44.5 [interquartile range, 43-46.8] vs median, 48 [interquartile range, 46-50], respectively; P = .009). The ROC curve analysis determined a cutoff value of 46.5 points (sensitivity, 73%; specificity, 63.6%), indicating that the KA scores exhibited a relatively high predictive value for running-related injuries (area under the ROC curve, 0.764 [95% CI, 0.600-0.930]). The risk ratio for group division based on the cutoff value was 2.590 (95% CI, 1.329-5.047). These findings demonstrated that the KA test is an effective self-screening tool for predicting the risk of running-related injuries in elite male long-distance runners.

Sex differences in body composition and shock attenuation during running

Running-related impact shock is absorbed via biological tissue deformation. Given known sex differences in body composition, shock attenuation may also differ between sexes thereby influencing sex-specific running-related injury risk. This study examined sex differences in body composition and shock attenuation during running. Seventeen female (mean ± 1SD age: 34.7 ± 16.1) and twenty-one male runners (age: 29.0 ± 13.8) ran overground as inertial measurement units with triaxial accelerometers measured impact shock at the distal tibia and low-back. Frequency-domain axial and resultant shock attenuation were calculated between the low-back relative to the tibia using a transfer function of the power spectral density within 9–20, 21–35, and 36–50 Hz. Bone mineral density and content, fat and lean mass were measured in the lower extremity and pelvis/gynoid regions using dual x-ray absorptiometry. The association between sex and shock attenuation was tested using age-adjusted linear regression models, adjusted and unadjusted for body composition as a post-hoc analysis (α = 0.05). Body composition variables normalized to body mass were compared between sexes using independent samples t-tests (α = 0.05). Body composition differed between sexes (p-range: <0.001–0.01, Cohen’s d range: 0.17–2.41). Before adjusting for body composition, sex was not significantly associated with axial or resultant shock attenuation (p > 0.05), but adjusting for select body composition variables like lower extremity lean and bone mass revealed greater attenuation in females than males (β-range: −124.76 to −46.42, negative indicates greater attenuation; p-range = 0.004–0.04). Sex may not influence shock attenuation during running, but body composition must be accounted for to better understand this association and consequently sex-specific tissue capacities relative to applied loads.

Advancing our ability to quantify an individual’s habitual motion path and deviation when running

The habitual motion path theory states that exhibiting kinematic differences between running and habitual movement tasks may increase the risk of running-related injury. Staying near one’s habitual motion path when running has been shown to reduce compression of the knee joint cartilage, a proxy for decreased soft tissue loading. Previous efforts to quantify one’s habitual motion path and deviation when running have utilised just one habitual movement and one time point during the stance phase of running. The methodology advancement described in this manuscript focused on advancing habitual motion path theory research by (1) increasing the number of movements for quantifying an individual’s habitual motion path; and (2) utilising the entire stance phase when running to quantify deviations as opposed to one time point. We liken the advancements in the method described in this manuscript as with the first method we were using a ruler to assess one’s habitual motion path and deviations, and now we are using calipers; providing a more accurate understanding of an individual’s unique habitual movement and deviation when running. We also discuss future potential research avenues related to understanding running biomechanics and footwear effects that this tool will allow us to explore.

Predictors of Running-Related Injury Among Recreational Runners: A Prospective Cohort Study of the Role of Perfectionism, Mental Toughness, and Passion in Running.

The health benefits associated with recreational running are challenged by the occurrence of running-related injuries (RRIs). Effective preventive measures require knowledge of sport injury etiology. Psychological factors such as perfectionism, mental toughness, and passion are believed to predispose to sports injury by influencing training behaviors, motivation to run, and suppression of feelings of fatigue and pain. Yet their association with RRIs are understudied. Perfectionism, mental toughness, and passion predict an increased risk of RRIs in recreational runners. Prospective cohort study. Level 3. A total of 143 recreational runners (age 34.9 ± 13.9 years, 37% women) with a response rate of 76.5% answered an online questionnaire about their characteristics, running behaviors, and psychological variables (perfectionism, mental toughness, and running passion) as well as a sports injury survey. Then, as a primary outcome, RRIs were recorded biweekly for 6 months. The incidence of injuries was expressed as RRI per 1000 hours of running. The association between predictive factors and RRIs was estimated using logistic regression. The incidence of RRIs during follow-up was 5.16 per 1000 hours of running. The knee was the location injured most often (26.4%), followed by the foot (18.9%) and lower leg (13.2%). Higher obsessive passion (OP) for running (odds ratio [OR], 1.11; 95% CI, 1.04-1.20) and perfectionistic concerns (OR, 1.22; CI,1.05-1.41) were associated with a greater risk of RRIs, as were previous injury (OR, 2.49; CI,1.10-5.70), weekly running distance (OR,1.10; CI, 1.03-1.16), and both supinated (OR, 4.51; CI, 1.11-18.30) and pronated (OR, 3.55; CI, 1.29-9.80) foot type. Following a running schedule (OR, 0.24; CI, 0.09-0.66) was associated with a lower risk of RRIs. History of previous RRI, pronated and supinated foot type, weekly running distance, perfectionistic concerns, and OP increased RRI risk in recreational runners. Following a running schedule was a protective factor. Multiple factors, including runners' psychological characteristics, predict RRIs. These findings can inform the development of injury risk management strategies.

Gait asymmetry in spatiotemporal and kinetic variables does not increase running-related injury risk in lower limbs: a secondary analysis of a randomised trial including 800+ recreational runners

ObjectiveTo investigate asymmetry in spatiotemporal and kinetic variables in 800+ recreational runners, identify determinants of asymmetry, investigate if asymmetry is related to greater running injury risk and compare spatiotemporal and...

The Running Injury Continuum: A qualitative examination of recreational runners' description and management of injury.

A critical step in understanding and preventing running-related injuries (RRIs) is appropriately defining RRIs. Current definitions of RRIs may not represent the full process of injury development, failing to capture lower levels of injury that many athletes continue to train through. Understanding runners' description and management of the injury development process may allow for a more appropriate examination of all levels of injury. This study aimed to examine recreational runners' description and management of the injury development process. A qualitative focus group study was undertaken. Seven semi-structured focus groups with male (n = 13) and female (n = 18) recreational runners took place. Focus groups were audio and video recorded, and transcribed verbatim. Transcripts were reflexively thematically analysed. A critical friend approach was taken to data coding. Multiple methods of trustworthiness were executed. Runners describe injury on a nine-level continuum, ranging from injury-free to career-ending injury. There are lower and higher levels of injury. Each level of injury is described across four categories of descriptors; physical description, outcome (effect on running and daily life), psychological description, and management. The Running Injury Continuum is a tool that can be used for injury surveillance (for healthcare professionals and researchers) and for research investigating RRI risk factors. Healthcare professionals, researchers and coaches must ensure they monitor the development of all levels of RRIs, across all categories of descriptors. Runners need to be educated regarding appropriate self-management strategies for lower level injuries, with access to evidence-based information being a critical management tool.

Changes in Running Kinematics and Kinetics Following a 10 km Run.

Little is known about changes in kinetics or kinematics following a 10 km training run. This information has implications on risk of running-related injury. The purpose of this study was to examine the effect of a 10 km run on running kinematics and kinetics in a sample of experienced runners. Cross-Sectional Study. Nineteen runners ages 18-48 (7 female, 12 male) consented to participate including eight (3 female, 5 male) ultra-runners, and 11 (4 female, 7 male) recreational runners. Following collection of demographic data and completion of a short running survey, participants did a 6-minute run at their self-selected running speed to acclimate to the instrumented treadmill. Reflective markers were placed over designated anatomical landmarks on both sides of the pelvis as well as the left lower extremity and marked with a skin pen. Subjects then ran on the treadmill and 30 seconds of video data were recorded at 240 frames/sec using a high-speed camera for the sagittal plane and the frontal plane. Simultaneously, ground reaction forces (GRFs) were recorded at 1200 Hz through the treadmill's embedded force plates. Each runner then ran 10 km on a paved trail at their self-selected pace. Immediately following the run, reflective markers were reattached, guided by markings placed before the run, and a 30-second post-run trial of the video and GRF data were recorded. Video data were analyzed using Kinovea software to measure the kinematic variables of interest. Paired t-tests with Bonferroni corrections were used to find if significant differences existed between pre- and post-run data for all kinematic and kinetic variables. No significant or clinically relevant differences existed between the pre- and post-run measurements for the kinematic or kinetic variables. The only significant difference noted between the ultra-runners and recreational runners was that the ultra-runners had significantly higher cadence (p=0.045). A 10 km run at a self-selected pace did not result in change in the mean kinematic or kinetic variables in this group of experienced runners. Ultra-runners employ higher cadence than recreational runners, but their kinematics and kinetics are similar. Level 3.

PCA of Running Biomechanics after 5 km between Novice and Experienced Runners.

Increased running experience appears to lower the risk of running-related injuries, but the mechanisms underlying this are unknown. Studying the biomechanics of runners with different running experiences before and after long-distance running can improve our understanding of the relationship between faulty running mechanics and injury. The purpose of the present study was to investigate if there were any differences in lower-limb biomechanics between runners after a 5 km run. Biomechanical data were collected from 15 novice and 15 experienced runners. Principal component analysis (PCA) with single-component reconstruction was used to identify variations in running biomechanics across the gait waveforms. A two-way repeated-measures ANOVA was conducted to explore the effects of runner and a 5 km run. Significant runner group differences were found for the kinematics and kinetics of lower-limb joints and ground reaction force (GRF) with respect to the magnitude across the stance phase. We found that novice runners exhibited greater changes in joint angles, joint moments, and GRFs than experienced runners regardless of the prolonged running session, and those patterns may relate to lower-limb injuries. The results of this study suggest that the PCA approach can provide unique insight into running biomechanics and injury mechanisms. The findings from the study could potentially guide training program developments and injury prevention protocols for runners with different running experiences.

Instructions Promoting an External Focus Are More Effective for Altering Impact Forces in Female Runners.

Previous studies have found that instructions promoting an external focus (EF) tend to be more effective for movement pattern retraining compared to instructions promoting an internal focus (IF), for a variety of movement tasks. However, few studies have examined how different types of instructions affect running mechanics associated with running-related injury risk. Therefore, the purpose of this study was to compare the effects of instructions promoting different attentional foci on impact forces during running. Cross-sectional study. Twenty uninjured female recreational runners ran at a self-selected speed with their typical pattern (no instructions condition) on an instrumented treadmill that measured ground reaction forces. Next, they were given 2 sets of instructions intended to alter their running pattern; one promoted an IF and the other promoted an EF. Repeated-measures analysis of variance was used to compare impact peaks and loading rates across the conditions (no instructions, IF, and EF), with post hoc tests conducted in the case of a significant omnibus test. There were differences among the conditions in the impact peaks (P < .001) and loading rates (P < .001). Impact peaks were lower for the IF (P = .002) and EF (P < .001) conditions compared to the no instructions condition. Loading rates were lower for the EF condition compared to the no instructions (P < .001) and IF (P < .001) conditions; there was no difference between the IF and no instructions conditions (P = .24). Our findings indicate that instructions promoting an EF may be more effective at reducing loading rates during running compared to instructions promoting an IF. Clinicians should consider these findings when attempting to retrain a runner's running pattern.

Comparison of different machine learning models to enhance sacral acceleration-based estimations of running stride temporal variables and peak vertical ground reaction force

ABSTRACT Machine learning (ML) was used to predict contact () and flight () time, duty factor (DF) and peak vertical force () from IMU-based estimations. One hundred runners ran on an instrumented treadmill (9–13 km/h) while wearing a sacral-mounted IMU. Linear regression (LR), support vector regression and two-layer neural-network were trained (80 participants) using IMU-based estimations, running speed, stride frequency and body mass. Predictions (remaining 20 participants) were compared to gold standard (kinetic data collected using the force plate) by calculating the mean absolute percentage error (MAPE). MAPEs of did not significantly differ among its estimation and predictions (P = 0.37), while prediction MAPEs for , and DF were significantly smaller than corresponding estimation MAPEs (P ≤ 0.003). There were no significant differences among prediction MAPEs obtained from the three ML models (P ≥ 0.80). Errors of the ML models were equal to or smaller than (≤32%) the smallest real difference for the four variables, while errors of the estimations were not (15–45%), indicating that ML models were sufficiently accurate to detect a clinically important difference. The simplest ML model (LR) should be used to improve the accuracy of the IMU-based estimations. These improvements may be beneficial when monitoring running-related injury risk factors in real-world settings.

Wearable technology assessing running biomechanics and prospective running-related injuries in Active Duty Soldiers

ABSTRACT The purpose of this study was to determine if running biomechanical variables measured by wearable technology were prospectively associated with running injuries in Active Duty Soldiers. A total of 171 Soldiers wore a shoe pod that collected data on running foot strike pattern, step rate, step length and contact time for 6 weeks. Running-related injuries were determined by medical record review 12 months post-study enrollment. Differences in running biomechanics between injured and non-injured runners were compared using independent t-tests or ANCOVA for continuous variables and chi-square analyses for the association of categorical variables. Kaplan–Meier survival curves were used to estimate the time to a running-related injury. Risk factors were carried forward to estimate hazard ratios using Cox proportional hazard regression models. Forty-one participants (24%) sustained a running-related injury. Injured participants had a lower step rate than non-injured participants, but step rate did not have a significant effect on time to injury. Participants with the longest contact time were at a 2.25 times greater risk for a running-related injury; they were also relatively slower, heavier, and older. Concomitant with known demographic risk factors for injury, contact time may be an additional indicator of a running-related injury risk in Active Duty Soldiers.

Effects of long-term running on the structure and biochemical composition of knee cartilage in males: a cross-sectional study.

Running has been widely recognized as a beneficial activity for improving physical fitness, but it can also increase the risk of running-related injuries (RRIs). This study aims to assess the impact of long-term running on the structural and biochemical composition of the knee. This study recruited a total of 32 participants, including 16 male recreational runners, aged 28-49 years, with a running experience of 2-7 years, and 16 matched sedentary controls. Magnetic resonance (MR) scans of T2* mapping and three-dimensional double-echo steady-state (3D-DESS) were performed on all participants. The volumes, thickness, and T2* values of joint articular cartilage were obtained via automatic segmentation software. Compared with the sedentary controls, runners exhibited significant increases in the volumes of both the femoral medial articular cartilage and the tibial medial articular cartilage. Additionally, there were significant increases in the thickness of several cartilage regions, including femoral medial cartilage, femoral medial articular cartilage, femoral medial thickness, femoral lateral cartilage, and tibial medial articular cartilage. Notably, the T2* values in the femoral lateral and tibial lateral cartilage of runners decreased significantly, while those in the patellar cartilage and medial tibial cartilage increased significantly. Runner pace was negatively correlated with the overall knee cartilage thickness (r=-0.556; P=0.02), femoral cartilage thickness (r=-0.533; P=0.03), and volume (r=-0.532; P=0.03) but positively correlated with the T2* value of the patellar cartilage (r=0.577; P=0.01). Our study suggests that long-term mechanical stress from running may lead to increased thickness and volume in certain knee joint cartilage regions, possibly enhancing the functional adaptability of knee cartilage. The varying changes in T2* value in the tibial and fibular cartilage areas may indicate differing adaptability to pressure.

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

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. 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. 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. 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.

Resistance Exercise for Improving Running Economy and Running Biomechanics and Decreasing Running-Related Injury Risk: A Narrative Review.

It is well-accepted that at least a certain amount of resistance exercise (RE) is recommended for most endurance athletes. In this review, we aim to summarize the evidence regarding the effects of RE on running economy, running biomechanics, and running-related injury risk in endurance runners. The evidence robustly shows that lower limb RE is effective for improving running economy and performance, with a combination of strength and plyometric training being recommended to improve RE. Isometric training is also emerging as a possible alternative to implement during periods of high overall training load. Lower limb RE may change some aspects of joint kinematics during running; however, the evidence regarding the effects on kinetics is limited. Lower limb RE may help reduce running-related injury risk, but further evidence is needed.

Gait and Neuromuscular Changes Are Evident in Some Masters Club Level Runners 24-h After Interval Training Run.

PurposeTo examine the time course of recovery for gait and neuromuscular function immediately after and 24-h post interval training. In addition, this study compared the impact of different statistical approaches on detecting changes.MethodsTwenty (10F, 10M) healthy, recreational club runners performed a high-intensity interval training (HIIT) session consisting of six repetitions of 800 m. A 6-min medium intensity run was performed pre, post, and 24-h post HIIT to assess hip and knee kinematics and coordination variability. Voluntary activation and twitch force of the quadriceps, along with maximum isometric force were examined pre, post, and 24-h post significance HIIT. The time course of changes were examined using two different statistical approaches: traditional null hypothesis significance tests and “real” changes using minimum detectable change.ResultsImmediately following the run, there were significant (P < 0.05) increases in the hip frontal kinematics and coordination variability. The runners also experienced a loss of muscular strength and neuromuscular function immediately post HIIT (P < 0.05). Individual assessment, however, showed that not all runners experienced fatigue effects immediately post HIIT. Null hypothesis significance testing revealed a lack of recovery in hip frontal kinematics, coordination variability, muscle strength, and neuromuscular function at 24-h post, however, the use of minimum detectable change suggested that most runners had recovered.ConclusionHigh intensity interval training resulted in altered running kinematics along with central and peripheral decrements in neuromuscular function. Most runners had recovered within 24-h, although a minority still exhibited signs of fatigue. The runners that were not able to recover prior to their run at 24-h were identified to be at an increased risk of running-related injury.

A Re-examination of the Measurement of Foot Strike Mechanics During Running: The Immediate Effect of Footwear Midsole Thickness.

PurposeMidsole cushioning thickness (MT) is a key component of running footwear that may influence the stiffness setting of the joints, performance enhancement, and injury prevention. Most studies that have investigated the influence of manipulating shoe midsole characteristics on foot strike patterns and vertical force loading rates have not considered the dynamic conditions of initial landing and the associated initial lower limb joint stiffness. In this study, we examined the effect of running in shoes with large changes in MT on both the posture and dynamics associated with foot strike.Methods12 injury-free runners with habitual rearfoot strike patterns ran at 4.5 m/s along a 40-m runway in shoe conditions with MT of 30, 42, and 54 mm, respectively. Ground reaction force and the right leg kinematic data were collected. One-way repeated measures ANOVA was conducted to statistically analyze the effect of MT on key variables linked to foot strike.ResultsIncreased midsole thickness resulted in a slightly flatter foot strike posture (p < 0.05), a decreased shank retraction velocity (p < 0.05), and an increase in forward horizontal foot velocity (p < 0.05), all at initial ground contact. Vertical force loading rates were reduced with increasing MT (p < 0.05), but this was associated with large increases in the initial ankle and knee joint stiffness (p < 0.05).ConclusionAdjustments in the initial conditions of contact with the ground during running were seen in both the posture and dynamics of the lower limbs. To help to mitigate the impact severity from foot-ground collision with the thinnest shoe condition, there was an increased shank retraction velocity and decreased forward velocity of the foot at landing. These active impact-moderating adaptations likely served to reduce the changes in impact severity expected due to midsole material properties alone and should be considered in relation to altering the risk of running-related injuries.

Changes in spatiotemporal parameters, joint and CoM kinematics and leg stiffness in novice runners during a high-intensity fatigue protocol.

Even though running enjoys growing popularity, the effects of fatigue on the running kinematics of novices have rarely been studied. This is surprising, given the risk of running-related injuries when detrimental movement patterns are adopted. Therefore, the goal of the present study was to characterize the effects of fatigue induced by a high-intensity running protocol on spatiotemporal and stiffness parameters as well as on joint kinematics and center of mass (CoM) motion in novice runners. 14 participants performed a standardized treadmill familiarization and ran at 13 km/h until voluntary exhaustion. Kinematics were captured using a 3D motion capture system. Spatiotemporal and stiffness parameters as well as the range of motion (RoM) of the joints and CoM were compared by use of paired t-tests. Time series of the joint angles and CoM motion were analyzed by the statistical parametric mapping method. The results revealed that novice runners did not change spatiotemporal or stiffness parameters, but showed adaptations in joint kinematics, e.g. decreased dorsiflexion and increased pronation in the ankle joint during the swing phase. The findings of this study underline the importance of strengthening the ankle joint to prevent excessive pronation and increase its stability in novice runners.

Vertical Loading Rate Is Not Associated with Running Injury, Regardless of Calculation Method.

Loading rate (LR), the slope of the vertical ground reaction force (vGRF), is commonly used to assess running-related injury risk. However, the relationship between LR and running-related injuries, including bone stress injuries (BSI), is unclear. Inconsistent findings may result from the numerous LR calculation methods that exist and their application across different running speeds. This study aimed to assess the influence of calculation method and running speed on LR values and to determine the association of LR during healthy running with subsequent injury. Healthy preseason running data and subsequent injury records from Division I cross-country athletes ( n = 79) over four seasons (2015-2019) at 2.68 m·s -1 , preferred training pace, and 4.47 m·s -1 were collected. LR at each speed was calculated four ways: 1) maximum and 2) average slope from 20% to 80% of vGRF magnitude at impact peak (IP), 3) average slope from initial contact to IP, and 4) average slope from 3% to 12% of stance time. Linear mixed effects models and generalized estimation equations were used to assess LR associations. LR values differed depending on speed and calculation method ( P value <0.001). The maximum slope from 20% to 80% of the vGRF at 4.47 m·s -1 produced the highest LR estimate and the average slope from initial contact to IP at 2.68 m·s -1 produced the lowest. Sixty-four injuries (20 BSI) were observed. No significant association was found between LR and all injuries or BSI across any calculation method ( P values ≥0.13). Calculation method and running speed result in significantly different LR values. Regardless of calculation method, no association between LR and subsequent injury was identified. Thus, healthy baseline LR may not be useful to prospectively assess running-related injury risk.

Is self-regulation key in reducing running-related injuries and chronic fatigue? A randomized controlled trial among long-distance runners

Runners have a high risk of getting injured compared to practitioners of other sports, and reducing this risk appears challenging. A possible solution may lie in the self-regulatory behavior of runners and their passion for running, which are promising predictors of runners' risk of running-related injuries (RRIs) and chronic fatigue. Therefore, in the present study, we investigated to what extent a mobile application (“app”), called REMBO, could reduce the risk of RRIs and chronic fatigue by externally supporting self-regulation in a personalized fashion. Long-distance runners (N = 425; 243 men, 182 women; M age = 44.7 years), training for half and whole marathon distances, took part in our randomized controlled trial. Runners were randomly allocated to theintervention group with access to the app (n = 214) or to the control group with no access to the app (n = 211). We tested the effectiveness of the app according to the intention-to-treat protocol and via a dose-response analysis, finding no statistically significant effects with regard to RRIs and chronic fatigue. Furthermore, an exploratory latent risk profile subgroup analysis found no evidence that any reductions in RRIs or chronic fatigue due to the app intervention differed across low-risk, medium-risk, and high-risk psychological profiles of runners. Across our study, adherence was relatively low, reasons for which are discussed based on feedback from participants. In our discussion, we outline the implications of the app intervention not achieving its intended effect and list several recommendations that might steer toward more success in preventing RRIs and chronic fatigue in the future.