Running-related Overuse Injuries Research Articles

Association Between Running Characteristics and Lower Extremity Musculoskeletal Injuries in United States Military Academy Cadets.

Running-related overuse injuries are common among recreational runners; however, there is currently little prospective research investigating the role of running characteristics on overuse injury development. To investigate the relationship between running characteristics and lower extremity musculoskeletal injury (MSKI). Cohort study; Level of evidence, 2. The study included 827 incoming cadets of the class of 2020 at the United States Military Academy. Before cadet basic training, running spatiotemporal parameters (stride length, ground contact time, and cadence) were recorded for each participant, and foot-strike pattern was analyzed. Demographic data were recorded and analyzed as potential covariates. Lower extremity MSKIs sustained over the 9 weeks of cadet basic training were documented. Kaplan-Meier survival curves were estimated, with time to incident lower extremity MSKI as the primary outcome, by level of the independent predictor variables. Risk factors or potential covariates were carried forward into multivariate Cox proportional hazards regression models. Approximately 18.1% of participants incurred a lower extremity MSKI resulting in ≥3 days of activity limitation during cadet basic training. Univariate analysis indicated that participants with the shortest stride length (<133.0 cm) were 39% more likely to incur any lower extremity MSKI and 45% more likely to incur an overuse MSKI than those with the longest stride length (>158.5 cm), and that participants with the longest ground contact time (>0.42 seconds) were twice as likely to incur any MSKI than those with the shortest contact time (<0.28 seconds). After adjusting for sex, weekly distance running 3 months before cadet basic training, and history of injury, multivariate regression analysis indicated that participants with the longest contact times were significantly more likely to incur overuse lower extremity MSKI than those with the shortest contact times (hazard ratio, 2.15; 95% CI, 1.06-4.37). There was no significant difference in risk of MSKI associated with foot-strike pattern or cadence. Study participants running with the longest ground contact times were 2.15 times more likely to incur an overuse lower extremity MSKI during cadet basic training than those with the shortest contact times. Also, study participants with the shortest stride length were 45% more likely to incur an overuse MSKI than those with the longest stride length.

Managing lower extremity loading in distance running by altering sagittal plane trunk leaning

BackgroundTrunk lean angle is an underrepresented biomechanical variable for modulating and redistributing lower extremity joint loading and potentially reducing the risk of running-related overuse injuries. The purpose of this study was to systematically alter the trunk lean angle in distance running using an auditory real-time feedback approach and to derive dose–response relationships between sagittal plane trunk lean angle and lower extremity (cumulative) joint loading to guide overuse load management in clinical practice. MethodsThirty recreational runners (15 males and 15 females) ran at a constant speed of 2.5 m/s at 5 systematically varied trunk lean conditions on a force-instrumented treadmill while kinematic and kinetic data were captured. ResultsA change in trunk lean angle from –2° (extension) to 28° (flexion) resulted in a systematic increase in stance phase angular impulse, cumulative impulse, and peak moment at the hip joint in the sagittal and transversal plane. In contrast, a systematic decrease in these parameters at the knee joint in the sagittal plane and the hip joint in the frontal plane was found (p < 0.001). Linear fitting revealed that with every degree of anterior trunk leaning, the cumulative hip joint extension loading increases by 3.26 Nm·s/kg/1000 m, while simultaneously decreasing knee joint extension loading by 1.08 Nm·s/kg/1000 m. ConclusionTrunk leaning can reduce knee joint loading and hip joint abduction loading, at the cost of hip joint loading in the sagittal and transversal planes during distance running. Modulating lower extremity joint loading by altering trunk lean angle is an effective strategy to redistribute joint load between/within the knee and hip joints. When implementing anterior trunk leaning in clinical practice, the increased demands on the hip musculature, dynamic stability, and the potential trade-off with running economy should be considered.

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

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

The effectiveness of telehealth gait retraining in addition to standard physical therapy treatment for overuse knee injuries in soldiers: a protocol for a randomized clinical trial

IntroductionRunning is the most common cardiovascular exercise in the military. However, there is a high incidence of running-related overuse injuries that reduces military readiness. Gait retraining is a common intervention to treat running-related injuries, but the high cost of equipment and lack of clinician expertise and availability reduces utilization. Gait retraining intervention in a telehealth format might improve feasibility. The purpose of this randomized clinical trial is to determine the effectiveness of a telehealth gait retraining intervention on pain, self-reported function, and biomechanical risk factors for injury in service members who present to a Military Health System physical therapy clinic with an overuse knee injury.MethodsThis is a parallel, two-arm, single-blind randomized clinical trial. The two independent variables are intervention (2 levels: telehealth gait retraining intervention with standard of care or only standard of care) and time (3 levels: baseline, 10 weeks or post-intervention, 14 weeks). Participants between the ages of 18 to 60 years will be included if they report knee pain during and/or after running to be anywhere from a 3 to a 7 on the numerical pain rating scale and demonstrate a rearfoot strike pattern. The primary dependent variables are as follows: (1) pain (worst pain during and/or after running) and (2) foot strike pattern (conversion rate from rearfoot to non-rearfoot foot strike pattern during running). Secondary outcomes include patient self-reported function and running biomechanics.DiscussionThe effectiveness of a telehealth gait retraining intervention to reduce pain and modify foot strike pattern is not known. The results of this study may help determine the effectiveness and feasibility of a telehealth gait retraining intervention to reduce pain, change foot strike, improve function, and improve running gait biomechanics.Trial registrationClinicalTrials.gov, NCT04269473. Registered 05 February 2020.

Running-Related Overuse Injuries and Their Relationship with Run and Resistance Training Characteristics in Adult Recreational Runners: A Cross-Sectional Study.

This study aimed to characterize running-related injuries (RRIs), explore their relationship with run and resistance training (RT) parameters, and identify perceived prevention measures among adult recreational runners. An anonymous online survey was designed and distributed via social media and email. Data were analyzed with chi-square, t-test, or analysis of variance (ANOVA), with significance accepted at p ≤ 0.05. Data from 616 participants (76.8% female, age: 42.3 ± 10.5 y) were analyzed. Most runners (84.4%) had an injury history, with 44.6% experiencing one in the past year. The most common RRI sites included the foot/ankle (30.9%) and knee (22.2%). RRI prevalence was higher in those running >19 miles weekly (48.4%, p = 0.05), but there were no differences based on RT participation status. Among those using RT, relatively more RRIs were observed in runners who trained the hip musculature (50.3%, p = 0.005) and did not include the upper body (61.6%, p < 0.001). A disproportionately high RRI prevalence was found for several of the other risk-reduction strategies. RRIs remain a substantial problem, particularly around the ankle/foot and knee. Higher run volume and performance motives were positively associated with RRIs. Most runners incorporated RRI risk-reduction techniques, with over half using RT. The current study did not determine whether preventative strategies were implemented before or after injury; therefore, prospective studies controlling for previous injuries are required to evaluate the effectiveness of RT in preventing future RRIs.

Increasing Step Frequency Reduces Patellofemoral Joint Stress and Patellar Tendon Force Impulse More at Low Running Speed.

Patellofemoral pain syndrome and patellar tendinopathy are important running-related overuse injuries. This study investigated the interaction of running speed and step frequency alterations on peak and cumulative patellofemoral joint stress (PFJS) and patellar tendon force (PTF) parameters. Twelve healthy individuals completed an incremental running speed protocol on a treadmill at habitual, increased and decreased step frequency. Peak PFJS and PTF, peak rate of PFJS and PTF development, and PFJS and PTF impulse per kilometer (km) were calculated using musculoskeletal modeling. With increasing running speed, peak PFJS ( P < 0.001) and PTF ( P < 0.001) and peak rate of PFJS ( P < 0.001) and PTF ( P < 0.001) development increased, whereas PFJS ( P < 0.001) and PTF ( P < 0.001) impulse per km decreased. While increasing step frequency by 10%, the peak PFJS ( P < 0.001) and PTF ( P < 0.001) and the PFJS ( P < 0.001) and PTF ( P < 0.001) impulse per kilometer decreased. No significant effect of step frequency alteration was found for the peak rate of PFJS ( P = 0.008) and PTF ( P = 0.213) development. A significant interaction effect was found for PFJS ( P < 0.001) and PTF ( P < 0.001) impulse per km, suggesting that step frequency alteration was more effective at low running speed. The effectiveness of step frequency alteration on PFJS and PTF impulse per km is dependent on the running speed. With regard to peak PFJS and PTF, step frequency alteration is equally effective at low and high running speeds. Step frequency alteration was not effective for peak rate of PFJS and PTF development. These findings can assist the optimization of patellofemoral joint and patellar tendon load management strategies.

Surface effects on kinematics, kinetics and stiffness of habitual rearfoot strikers during running.

The surface effects on running biomechanics have been greatly investigated. However, the effects on rearfoot strike runners remain unknown. The purpose of this study was to investigate the effects of surfaces on the running kinematics, kinetics, and lower-limb stiffness of habitual rearfoot strikers. Thirty healthy male runners were recruited to run at 3.3 ± 0.2 m/s on a customized runway covered with three different surfaces (artificial grass, synthetic rubber, or concrete), and their running kinematics, kinetics, and lower-limb stiffness were compared. Differences among the three surfaces were examined using statistical parametric mapping and one-way repeated-measure analysis of variance. There were no statistical differences in the lower-limb joint motion, vertical ground reaction force (GRF), loading rates, and lower-limb stiffness when running on the three surfaces. The braking force (17%-36% of the stance phase) and mediolateral GRF were decreased when running on concrete surface compared with running on the other two surfaces. The moments of ankle joint in all three plane movement and frontal plane hip and knee joints were increased when running on concrete surface. Therefore, habitual rearfoot strikers may expose to a higher risk of running-related overuse injuries when running on a harder surface.

Recognition System of Human Fatigue State Based on Hip Gait Information in Gait Patterns

Fatigue is a common phenomenon in sports and affects sports performance. The production of fatigue during running increases the risk of sports-related injury. People with high physical demands, such as construction workers, soldiers and athletes, are often in a state of muscle fatigue, which may have an adverse effect on health and safety. It is necessary to take effective preventive measures when muscle fatigue occurs. In this paper, a wearable system for monitoring hip dynamics during human walking is proposed, and a machine learning method is used to evaluate fatigue level. The fatigue level of each subject was determined by monitoring the percentage of maximum oxygen uptake. Different percentages of oxygen uptake correspond to different exercise levels. The hip joint angle sensor used herein can sense real-time changes in the angle of the human hip joint, and the data can be used to objectively evaluate the fatigue level of the human body to reduce the risk of running-related overuse injuries. This system can be applied to a human exoskeleton device without increasing the burden on the wearer.

Symptomatic and asymptomatic pronated feet show differences in the forefoot abduction motion during jogging, but not in the arch deformation

ABSTRACT Pronated feet have been associated with higher risks of running-related overuse injuries than neutral feet. However, it remains unclear why some pronated feet develop running-related injuries, while others do not. This study aimed to examine the differences in foot kinematics during jogging among individuals with symptomatic pronated feet (SP), asymptomatic pronated feet (AP) and asymptomatic neutral feet (AN). Thirty-nine recreational runners were recruited and classified into the SP, AP and AN groups. Statistical parametric mapping (SPM) and ANOVA were used to identify kinematic differences among three groups. The SPM results showed that the SP had larger forefoot abduction than the AN and AP during jogging, while three groups had similar rearfoot eversion during jogging. Both the AP and SP had larger forefoot sagittal range of motion (ROM) (mean difference = 3.5 and 4.8 deg, respectively) and smaller rearfoot sagittal ROM (mean difference = 5.0 and 3.5 deg, respectively) than the AN. Forefoot abduction during jogging may have the potential to identify pronated feet at greater risk of injury. Pronated feet, symptomatic or not, have comparable large forefoot sagittal ROM, i.e., arch deformation, compared to neutral feet. The findings could have implications for the injury aetiology and intervention strategies for SP.

Bilateral differences in coordination variability among injured and uninjured runners: A prospective study

This prospective cohort study aimed to identify bilateral differences in coordination variability (CAV) to determine if limb-specific CAV or CAV asymmetry is associated with running-related overuse injury (RRI) development in recreational runners. Lower limb kinematics were collected at enrollment. Runners were classified as injured (n = 14) or controls (n = 17) based on RRI incidence during a ≥ 6-month follow-up. Pelvis-thigh, knee-shank, knee-ankle, and shank-ankle CAV was quantified bilaterally within thirds of stance using modified vector coding. Wilcoxon Signed-Rank tests compared CAV between limbs within each group, and Wilcoxon Rank-Sum tests compared CAV asymmetry between groups (α ≤ 0.05). Injured runners displayed elevated injured versus uninjured limb CAV during initial-stance for all couplings (p < 0.010,d(effect size) = 0.51–1.31) except pelvis-thigh (p = 0.060,d = 0.36). During mid-stance, the injured limb exhibited restricted knee-ankle CAV (p < 0.010,d = 0.413) and elevated pelvis-thigh CAV (p < 0.010,d = 0.23). Controls also displayed bilateral differences specifically in pelvis-thigh CAV across stance, shank-ankle CAV during initial-stance, in all couplings during mid-stance, and shank-ankle CAV during late-stance (p < 0.010–0.025,d = 0.09–0.63). Comparing CAV asymmetry between groups revealed lower asymmetry among injured runners compared with controls for knee-ankle coupling in mid-stance and all couplings except pelvis-thigh during late-stance (p < 0.010,d = 0.85–1.87). Injured runners also displayed greater knee-shank CAV asymmetry in mid-stance versus controls (p < 0.010,d = 0.85). Logistic regression (α ≤ 0.05) revealed that between-limb CAV asymmetry did not predict RRI (p = 0.161), however, the odds of RRI were > 20% in the limb with either elevated shank-ankle CAV in initial-stance (p = 0.020) or elevated knee-ankle CAV in mid-stance (p = 0.043) than the contralateral limb. Therefore, limb-specific CAV rather than degree of CAV asymmetry may influence risk of RRI.

Plantar Injuries in Runners: Is There an Association With Weekly Running Volume?

Running is an athletic activity that is increasingly gaining popularity. Despite its benefits, there are many suspected risk factors for running-related overuse injuries. The objective of this study is to describe injuries and clinical symptoms observed on the sole of the foot in runners, giving special attention to the weekly running volume. The literature presented in this narrative review is based on a non-systematic search of the Medline, Google Scholar, and ResearchGate databases and focuses on foot injuries (the full spectrum of the foot pathology from bones to tendons and plantar fascia, nerve, and joint disorders) in runners, which represents an important topic for both professional and recreational runners. The weekly running distance appeared to be one of the strongest predictors for future overuse injuries. Marathon training and average weekly running of over 20 km are possible predictive factors in the development of plantar foot injuries. The plantar medial aspect of the foot is the anatomic area of the foot that most frequently experiences pain, with numerous pathologic conditions. As a result, diagnosis is always a challenging task. The ability to obtain an accurate medical history and carefully perform a physical examination, together with good knowledge of the foot anatomy and kinesiology, are also proven to be key players in ensuring proper diagnosis.

Segment coordination and variability among prospectively injured and uninjured runners

ABSTRACT Coordinative variability (CAV) and underlying coordinative patterns are potential running-related overuse injury (RROI) mechanisms, but prospective analyses are needed. This study compared lower limb CAV and coordinative patterns between prospectively injured and uninjured runners. Knee, shank, and ankle kinematics were collected for 39 recreational runners at the beginning of a 6-month follow-up period. Subjects were classified as injured (n=21) or controls (n=18) based on RROI incidence during follow-up. CAV was quantified using modified vector coding. Time spent in each coordinative pattern category was quantified using binning frequency analysis. Coordinative patterns were classified as mechanically unsound if underlying joint/segment motions opposed anatomically allowable running motion. Wilcoxon Rank-Sum tests compared CAV and binning frequencies between groups within different stance portions for knee-shank, shank-ankle, and knee-ankle couplings (α≤0.05). During initial-stance, the injured group displayed significantly greater knee-ankle CAV (effect size (ES)=1.1), knee-shank CAV (ES=0.97), and greater frequency of mechanically unsound knee-shank (ES=0.72) and shank-ankle (ES=0.63) motion. During mid-stance, the injured group displayed lower frequency of mechanically sound knee-ankle motion (ES=0.31). In late-stance, the injured group displayed greater shank-ankle CAV (ES=0.11). Mechanically unsound coordinative patterns along with greater knee-ankle and shank-ankle CAV potentially lead to RROI.

Risk Of Running-related Injury Associated With Center Of Mass Acceleration Complexity

Dynamical systems theory suggests that examining the complexity of biological signals may be more sensitive in differentiating between groups of varying health status, including predicting who may develop a running-related overuse injury (RROI). This theory has yet to be tested in prospective running studies. PURPOSE: To evaluate if changes in complexity, quantified by mean control entropy, of center of mass (COM) resultant acceleration during running is associatedwith RROI development. METHODS: 30 collegiate runners wore an ActiGraph GTX3+ during ‘easy’ training runs throughout a cross-country season. Clinician-diagnosed RROI were reported via an online survey. Complexity was calculated on the resultant acceleration time series from each run. Cox proportional hazards analysis assessed injury risk as a function of the mean complexity for each runner across the season and the change in complexity per week. RESULTS: Seven runners sustained an injury. Across all 30 participants over the season, the mean ± 1SD complexity was 0.623 ± 0.086 units. The mean change in complexity over the course of the cross country season was -0.0014 ± 0.0043 units per week. Although not statistically significant, each 0.1-unit increase in complexity was associated with a 1.65-fold increase in injury rate (95% CI 0.70-3.89, p=0.30) and a 0.01-unit increase in complexity per week was associated with a 1.50-fold increase in injury rate (95% CI 0.06-35.5, p = 0.80). CONCLUSION: These preliminary findings suggest that COM complexity could at least contribute to RROI detection strategies in cross-country runners. Given these preliminary results, additional prospective studies with larger sample sizes are necessary to further assess relationships between baseline complexity and changes in complexity during running training that can be monitored with wearable technology.

Running on the hypogravity treadmill AlterG® does not reduce the magnitude of peak tibial impact accelerations

Summary Background Hypogravity treadmills like the AlterG® have become a popular exercise tool especially in return-to-sports and return-to-competition rehabilitation programmes for distance runners, triathletes, footballers and further sports disciplines. By applying a slight positive air pressure in a chamber around the lower limbs, the effective bodyweight force is reduced, thereby reducing gravity load to the musculoskeletal system. So far it was unclear in how far that hypogravity unloading also affects peak accelerations at the tibiae, a common site of running-related overuse injuries. Material and Methods Fifteen well-trained male runners (peak oxygen consumption of 60 ± 4 ml min-1 kg-1) completed three incremental treadmill tests until volitional exhaustion in randomised order, two of which on the hypogravity treadmill AlterG® at 80% and 60% effective bodyweight, respectively, and the third on a conventional treadmill, i.e. at 100% gravity. Triaxial accelerations at the distal portions of both tibiae were captured throughout the three (hypo-)gravity conditions and all running speeds, along with the physiological cost of running in terms of heart rate, oxygen consumption and rating of perceived exertion. Results Mean peak tibial accelerations at impact and active push-off amounted to 12.9 ± 2.3 g0, 12.6 ± 1.9 g0 and 12.5 ± 2.3 g0 for 12–18 km h-1 at 100%, 80% and 60% effective bodyweight, respectively (g0 ≈ 9.81 m s-2). They were not reduced by hypogravity unloading within measurement uncertainty (p = 0.668). However, they exhibited a clear dependence on running speed (p elevated on the AlterG® (p Conclusions Distal tibial accelerations are not reduced in hypogravity running on the AlterG® treadmill in terms of absolute speeds, and are elevated in terms of relative speeds, i.e. at running speeds demanding the same physiological effort. Thus, precaution should be taken by clinicians and coaches when planning rehabilitation programmes for athletes with a recent injury background at the distal tibiae. The cause for the ineffectiveness of hypogravity running in reducing tibial acceleration load is most probably a subconscious energetic optimisation in human running motor control: For energetic reasons, the leaps of each step become flatter under hypogravity instead of steeper, whereas the latter would have intuitively been expected because of the lower effective acceleration of free fall. Level of Evidence: Ib

Association Between Running Shoe Characteristics and Lower Extremity Injuries in United States Military Academy Cadets

Background: Running-related overuse injuries are very common among recreational runners, with the reported annual injury rates ranging from 39% to 85%. Relatively few large prospective cohort studies have been conducted to investigate injury risk associated with different running shoe characteristics, and the results of the existing studies are often contradictory. Purpose/Hypothesis: The purpose was to investigate the relationship between running shoe characteristics and lower extremity musculoskeletal injury. It was hypothesized that the risk of injury would be increased in individuals wearing shoes with minimal torsional stiffness and heel height compared with those wearing shoes with greater levels of torsional stiffness and heel height. Study Design: Cohort study; Level of evidence, 2. Methods: The study included 1025 incoming cadets. Shoe torsional stiffness and heel height were calculated and recorded. Demographic data were recorded and analyzed as potential covariates. Lower extremity injuries sustained over 9 weeks during cadet basic training were documented by use of the Armed Forces Health Longitudinal Technology Application and the Cadet Illness and Injury Tracking System. Kaplan-Meier survival curves were estimated, with time to incident lower extremity injury as the primary outcome by level of the independent predictor variables. Risk factors or potential covariates were carried forward into multivariable Cox proportional hazards regression models. Absolute and relative risk reduction and numbers needed to treat were calculated. Results: Approximately 18.1% of participants incurred a lower extremity injury. Cadets wearing shoes with moderate lateral torsional stiffness were 49% less likely to incur any type of lower extremity injury and 52% less likely to incur an overuse lower extremity injury than cadets wearing shoes with minimal lateral torsional stiffness, both of which were statistically significant observations. Injury risk was similar among cadets wearing shoes with minimal and extreme lateral torsional stiffness. Conclusion: Shoes with mild to moderate lateral torsional stiffness may be appropriate in reducing risk of lower extremity injury in cadets. Shoes with minimal lateral torsional stiffness should be discouraged in this population.

Measuring biomechanical loads and asymmetries in junior elite long-distance runners through triaxial inertial sensors

Summary Background Despite its various positive health effects, long-distance running implies substantial biomechanical loads on the musculoskeletal system, especially in a competitive context. The incidence of running-related overuse injuries is high, especially for the tibia being one of the predominant injury localisations. Tibial impact accelerations are an established valid proxy measure for impact forces and, as such, considered a more direct estimate of tibial bone load than ground reaction forces. Assessing individual tibial and upper-body impact accelerations may help balancing biomechanical loads during training for long-distance running and triathlon. Material and methods We employed inexpensive, wireless, lightweight, triaxial inertial measurement units (IMUs) as wearables for measuring tibial, sacral and scapular impact loads and asymmetries in 45 healthy junior-elite long-distance runners at submaximal running speeds. Moreover, we investigated the effects of ground surface vs. running speed on tibial load in 8 well-trained, healthy runners and triathletes. Results Mean peak tibial accelerations in junior elite long-distance runners ranged between 14 ± 3 and 16 ± 3 g (g ≈ 9.81 m s−1) for running speeds of 14–16 km h−1. Corresponding mean peak sacral and scapular accelerations amounted to 4 ± 1 g to 5 ± 1 g (32 ± 8% of tibial load) and 4 ± 1 g (27 ± 6%), respectively. Observed lateral asymmetries in tibial and scapular accelerations yielded mean absolute values of 9 ± 8% (95th percentile of 24%) and 9 ± 10% (32%). The effect of running speed on tibial accelerations was approximately twice as large as the effect of ground surface. Among asphalt, tartan, treadmill and turf, only turf induced a significantly lower tibial load in well-trained runners. Conclusions IMU sensors represent a promising tool for assessing biomechanical loads and asymmetries in running under field conditions. With the orientation values derived in this study, they may be used to reduce individual risks of overuse injuries and, in future, possibly to assess running efficiency. Level of evidence Ib.

Using wearable sensors to classify subject-specific running biomechanical gait patterns based on changes in environmental weather conditions.

Running-related overuse injuries can result from a combination of various intrinsic (e.g., gait biomechanics) and extrinsic (e.g., running surface) risk factors. However, it is unknown how changes in environmental weather conditions affect running gait biomechanical patterns since these data cannot be collected in a laboratory setting. Therefore, the purpose of this study was to develop a classification model based on subject-specific changes in biomechanical running patterns across two different environmental weather conditions using data obtained from wearable sensors in real-world environments. Running gait data were recorded during winter and spring sessions, with recorded average air temperatures of -10° C and +6° C, respectively. Classification was performed based on measurements of pelvic drop, ground contact time, braking, vertical oscillation of pelvis, pelvic rotation, and cadence obtained from 66,370 strides (~11,000/runner) from a group of recreational runners. A non-linear and ensemble machine learning algorithm, random forest (RF), was used to classify and compute a heuristic for determining the importance of each variable in the prediction model. To validate the developed subject-specific model, two cross-validation methods (one-against-another and partitioning datasets) were used to obtain experimental mean classification accuracies of 87.18% and 95.42%, respectively, indicating an excellent discriminatory ability of the RF-based model. Additionally, the ranked order of variable importance differed across the individual runners. The results from the RF-based machine-learning algorithm demonstrates that processing gait biomechanical signals from a single wearable sensor can successfully detect changes to an individual’s running patterns based on data obtained in real-world environments.

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

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

The Role Of Off-axis Force In Running-related Overuse Injury

The Role Of Off-axis Force In Running-related Overuse Injury

Does Non-Running Physical Activity Contribute to the Risk of Developing a Running Related Overuse Injury?

Running related overuse injury (RROI) affects a significant proportion of runners annually. To date, only running mileage has been considered when quantifying the amount of loading that may elicit tissue micro-damage and injury, while the loading that occurs from activities of daily living and non-running physical activity has been ignored. By ignoring non-running physical activity (PA), we may be severely underestimating the amount of loading that leads to RROI. PURPOSE: To determine the role of daily non-running PA on the risk of RROI development among recreational and competitive runners. METHODS: As part of a larger prospective running injury pilot study, 50 recreational and competitive male and female runners will be enrolled and complete questionnaires regarding running history, injury history, and all forms of non-running daily PA. Participants will receive a FitBit Charge activity monitor to track PA for 24 hrs/day over 12 months. To date, questionnaires and a typical running gait analysis had been completed by 21 participants (9 male, 12 female; 27.5±6.3 years; BMI = 22.6±2.0 kg/m^2). RESULTS: Participants had mean±SD running experience of 8.6±5.6 years and run 24.1±15.2 mi/wk. Among n = 21 participants, RROI occurred within the past year in n = 4, within the past two years in n = 11, and in their lifetime in n = 16. Current mi/wk was 54% greater in those that had sustained a RROI in their lifetime compared with those that had not (No RROI = 15.3±4.5 mi/wk; Yes RROI 26.9±16.4 mi/wk, P=0.02). Total PA was not different between those who had and had not sustained a RROI in their lifetime or in the past 1-2 years (P>0.05). Non-running PA was greater in those that did not sustain a RROI in each time period, but the differences were not significant with this initial sample size (No RROI vs Yes RROI: lifetime 11.8±8.3 vs 7.1±7.2 hrs/wk, P>0.05; 1 yr: 8.7±8.2 vs 6.1±3.9 hrs/wk, P>0.05; 2 yr: 9.2±8.6 vs 7.3±6.8 hrs/wk, P>0.05). CONCLUSIONS: Results from the first 21 participants enrolled in this study support previous reports that running mi/wk may increase RROI risk. Given that total PA was the same between injured and non-injured runners in this sample, more hrs/wk spent in non-running PA vs running PA may reduce RROI risk. Continuous monitoring of PA collected in this 12 month study will provide evidence to support or reject this hypothesis.