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Background: 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. Purpose: To investigate whether the KA self-screening test score can predict running-related injuries in elite long-distance runners. Study Design: Cohort study; Level of evidence, 2. Methods: 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. Results: 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). Conclusion: 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. [ABSTRACT FROM AUTHOR]

Context: Understanding if roller massage prior to a run can mitigate fatigue-related decrements in muscle force production during prolonged running is important because of the association between fatigue and running-related injury. Objective: The authors investigated whether a bout of roller massage prior to running would (1) mitigate fatigue-related increases in vertical average load rate and free moment of the ground reaction force of running and (2) mitigate decreases in maximal countermovement jump height. Design: Repeated-measures study. Setting: Laboratory. Participants: A total of 14 recreational endurance athletes (11 men and 3 women) volunteered for the study. Interventions: A 12.5-minute foam roller protocol for the lower extremities and a fatiguing 30-minute treadmill run. Main Outcome Measures: Vertical average load rate, free moment, and maximal jump height before (PRE) and after (POST) the fatiguing treadmill run on separate experimental days: once where participants sat quietly prior to the fatiguing run (REST) and another where the foam roller protocol was performed prior to the run (ROLL). Results: A 2-way multiple analysis of variance found no significant differences in vertical average load rate, free moment, and jump height between PRE/POST times in both REST/ROLL conditions. Conclusions: The authors concluded that recreational endurance athletes maintain running mechanics and jump performance after a fatiguing run regardless of prerun roller massage and may not rely on prerun roller massage as a form of injury prevention. [ABSTRACT FROM AUTHOR]

Friction blisters are a common injury of the feet sustained by individuals participating in sporting, recreational, and military activities. The high incidence of friction blisters brings into question the effectiveness of common prevention strategies. The purpose of this article was to review current evidence for established blister-prevention strategies and to explore how these interventions address the factors that cause friction blisters. Preventive strategies, focusing on previously overlooked elements of the blister-causing mechanism, are proposed. Areas of future research that are much needed to reduce this common skin injury in active individuals are outlined. [ABSTRACT FROM AUTHOR]

Introduction: Running 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. Methods: This 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. Discussion: The 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 registration: ClinicalTrials.gov, NCT04269473. Registered 05 February 2020. [ABSTRACT FROM AUTHOR]

Abstract Introduction Running 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. Methods This 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. Discussion The 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 registration ClinicalTrials.gov, NCT04269473 . Registered 05 February 2020.

Iliotibial band friction syndrome is an overuse knee injury that is more common in runners. In IT band syndrome, pain, and tenderness are present over the lateral aspect of the knee. It is more common in females because of physiological and anatomical factors. The objective of this research was to determine and compare the effect of proximal to distal postural correction protocol with conventional physiotherapy program for IT band friction syndrome in female amateur runners. This study included 150 female amateur runners with IT band friction syndrome based on inclusion and exclusion criteria. Then the subjects were randomly allocated into group A and group B by simple random sampling method. Group A was given proximal to distal postural correction protocol and for group B conventional physiotherapy exercise program was given. Outcome measures used were a visual analog scale, postural assessment, tenderness assessment by palpation and Ober's test. Pre and post-assessment of the above measures was taken to conform the results. The results showed a statistically significant effect of the proximal to distal postural correction protocol as compared to a conventional exercise program for IT band friction syndrome in female amateur runners. There was a significant reduction in pain (<0.0001) in individuals in group A than the group B. Postural abnormalities in IT band friction syndrome were also significantly (<0.0001) resolved and the Ober's test came as 76% negative out of 100%positive patients. Based on results, it was concluded that the proximal to distal postural correction protocol is effective in female amateur runners. [ABSTRACT FROM AUTHOR]

Overuse injuries from running occur when the loading stimulus exceeds the tissue-specific loading capacity. Excessive running exposure (training errors) are important precursors to injury. Despite the intuitive relationship between loading, running volume, and injury, a definitive safe loading exposure that can reliably differentiate between injured and uninjured groups remains elusive. We propose that a singular focus on running-related factors such as gait, running surface change, sudden change in running volume, frequency of running, and acute-to-chronic workload make it difficult to identify reliable mechanisms of load-related running injury. Given that the accumulated loading from nonrunning exercise and physical activities of daily living can impose substantial and consequential load on the musculoskeletal system, we make the case for considering loading from all sources of physical activity as a contributor to running injury. [ABSTRACT FROM AUTHOR]

Two biomechanical mechanisms for the development of Achilles tendinopathy in runners have been proposed: A whipping mechanism characterized by prolonged and excessive rearfoot eversion, and a tearing mechanism characterized by high eccentric plantar flexor forces. The purpose of this pilot study was to determine if runners with and without a history of Achilles tendinopathy exhibited gait biomechanics consistent with either of these mechanisms. Seven male runners with previous or current Achilles tendinopathy and seven healthy male control runners were evaluated by three-dimensional gait analysis. Peak rearfoot eversion angle, rearfoot eversion excursion, duration of rearfoot eversion, and peak rearfoot inversion angle were compared between groups to evaluate the whipping mechanism of injury. Peak dorsiflexion angle, peak dorsiflexion velocity, and peak ankle power absorption were compared between groups to evaluate the tearing mechanism. Additionally, rearfoot eversion angle and sagittal plane ankle power waveforms were compared between groups using statistical parametric mapping. There were no differences in any rearfoot eversion, inversion, or dorsiflexion variables or waveforms during running in the Achilles tendinopathy group compared to controls. Rearfoot strike runners with Achilles tendinopathy do not exhibit running biomechanics consistent with either the whipping or tearing mechanisms of injury. • Peak rearfoot eversion is not different in runners with and without a history of Achilles tendinopathy. • Peak power absorption is not different in runners with and without a history of Achilles tendinopathy. • Peak dorsiflexion velocity and angle are not different in runners with and without a history of Achilles tendinopathy. • Rearfoot eversion and sagittal plane power waveforms are not different among runners with and without a history of Achilles tendinopathy. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to investigate short-interval intracortical inhibition (SICI) and muscle function in the triceps surae of runners with mid-portion Achilles tendinopathy (AT). Methods: Runners with (n = 11) and without (n = 13) AT were recruited. Plantar flexor isometric peak torque and rate of torque development (RTD) were measured using an isokinetic dynamometer. Triceps surae endurance was measured as single-leg heel raise (SLHR) to failure test. SICI was assessed using paired-pulse transcranial magnetic stimulation during a sustained contraction at 10% of plantar flexor isometric peak torque. Results: Triceps surae SICI was 14.3% (95% CI: −2.1 to 26.4) higher in AT than in the control group (57.9%, 95% CI: 36.2 to 79.6; and 43.6% 95% CI: 16.2 to 71.1, p = 0.032) irrespective of the tested muscle. AT performed 16 (95% CI: 7.9 to 23.3, p < 0.001) fewer SLHR repetitions on the symptomatic side compared with controls, and 14 (95% CI: 5.8 to 22.0, p = 0.004), fewer SLHR repetitions on the non-symptomatic compared with controls. We found no between-groups differences in isometric peak torque (p = 0.971) or RTD (p = 0.815). Perspective: Our data suggest greater intracortical inhibition for the triceps surae muscles for the AT group accompanied by reduced SLHR endurance, without deficits in isometric peak torque or RTD. The increased SICI observed in the AT group could be negatively influencing triceps surae endurance; thus, rehabilitation aiming to reduce intracortical inhibition should be considered to improve patient outcomes. Furthermore, SLHR is a useful clinical tool to assess plantar flexor function in AT patients. [ABSTRACT FROM AUTHOR]

Background: Variations in lower limb biomechanics can predispose to Achilles tendinopathy (AT). However, evidence on lower limb biomechanical factors associated with AT in runners is limited. Aims: This review aimed to examine the existing literature systematically to identify lower limb biomechanical factors associated with AT in runners. Methods: SCOPUS, ScienceDirect, and PUBMED databases were searched in April 2021 to investigate various lower limb biomechanics such as kinetics, kinematics, muscle activity, plantar pressure, and temporospatial parameter variables during running among AT patients. Results: Ten studies reported significant differences in knee flexion angle, ankle dorsiflexion, ankle eversion, touchdown angle, and plantarflexion moment between runners with and without AT. Plantar pressure and the ground reaction force variables were also found to be significant discriminators. Muscle activity of tibialis anterior, as well as medial and lateral gastrocnemius during various running phases showed significant differences associated with AT. Runners with AT displayed a longer duration of eversion and over-pronation compared to healthy controls. The mechanical effects of orthotic shoes in runners were able to reduce the incidence of AT. Conclusions: The findings of the current review indicated the biomechanical factors that could contribute to AT among runners. These factors can be assessed in clinical settings to minimise the injury risk among runners. The protocol of the review was registered at PROSPERO (CRD42021237500) on 18th March 2021. [ABSTRACT FROM AUTHOR]

Stressfrakturen und Stressreaktionen zählen zu den überlastungsbedingten Verletzungen („Overuse injuries") und können für betroffene Sportler mit erheblichen Trainings- und Wettkampfausfällen einhergehen. Repetitive, die Belastungs- und Anpassungsfähigkeit übersteigende Lasteinwirkungen verbunden mit intrinsischen und extrinsischen Risikofaktoren oder trainingstaktischen Fehlern gelten als Hauptursache für die Entstehung von Stressfrakturen. Diese und mögliche begleitende individuelle Risikoprofile stellen sich vielfältig dar und erfordern eine komplexe und oftmals interdisziplinäre Versorgung. Die Mehrheit der Stressfrakturen heilt unkompliziert aus und die Wiedererlangung der vollen Leistungs- und Belastungsfähigkeit ist in der Regel gegeben. Bei verzögerter oder inadäquater Diagnosestellung (einige Verletzungsentitäten erfordern eine konsequente Entscheidungsfindung zur operativen Therapie) oder bei fehlender Berücksichtigung sekundärer Risikofaktoren können jedoch prolongierte Heilungsverläufe, Rezidivverletzungen oder sogar multiple Verletzungslokalisationen gleichzeitig auftreten. Eine frühzeitige Diagnostik und der Beginn einer stadiengerechten Therapie, einschließlich der Berücksichtigung vorhandener Risikofaktoren, sind daher von essentieller Bedeutung. Stress fractures and stress reactions are among the injuries caused by overuse ("overuse injuries") and can result in significant training and competition failures for affected athletes. Repetitive load effects that exceed the ability to cope with stress and adaptability, combined with intrinsic and extrinsic risk factors or tactical training errors, are considered to be the main cause of stress fractures. These and possible accompanying individual risk profiles are diverse and require complex and often interdisciplinary care. The majority of stress fractures heal easily and the recovery of full performance and resilience is usually given. However, if the diagnosis is delayed or inadequate (some injury entities require consistent decision-making regarding surgical therapy) or if secondary risk factors are not taken into account, prolonged healing processes, recurrent injuries or even multiple injury locations can occur at the same time. An early diagnosis and the beginning of a stage-appropriate therapy, including the consideration of existing risk factors, are therefore of essential importance. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Willwacher, S, Fischer, KM, Rohr, E, Trudeau, MB, Hamill, J, and Brüggemann, G-P. Surface stiffness and footwear affect the loading stimulus for lower extremity muscles when running. J Strength Cond Res 36(1): 82–89, 2022—Running in minimal footwear or barefoot can improve foot muscle strength. Muscles spanning the foot and ankle joints have the potential to improve performance and to reduce overuse injury risk. Surface stiffness or footwear use could modify the intensity of training stimuli acting on lower extremity joints during running. The purpose of this study was to systematically investigate external ankle, knee, and hip joint moments during shod and barefoot running while considering the stiffness of the running surface. Two footwear conditions (barefoot and neutral running shoe) and 4 surface conditions (Tartan, Tartan + Ethylene Vinyl Acetate [EVA] foam, Tartan + artificial turf, Tartan + EVA foam + artificial turf) were tested at 3.5 m·s−1. Repeated measures analysis of variance revealed that barefoot running in general and running barefoot on harder surfaces increased and decreased ankle (between +5 and +26%) and knee (between 0 and −11%) joint moments, respectively. Averaged over all surfaces, running barefoot was characterized by a 6.8° more plantarflexed foot strike pattern compared with running shod. Foot strike patterns were more plantarflexed on harder surfaces; the effects, however, were less than 3°. Most surface effects were stronger in barefoot compared with shod running. Surface stiffness may be used to modulate the loading intensity of lower extremity muscles (in particular extrinsic and intrinsic foot muscles) during running. These results need to be considered when coaches advise barefoot running as a method to improve the strength of extrinsic and intrinsic foot muscles or when trying to reduce knee joint loading. [ABSTRACT FROM AUTHOR]

Background Collegiate distance runners often suffer from running overuse injuries (ROI). The Y-Balance Test (YBT) has the potential to predict ROI risk in collegiate runners. Purpose To investigate whether a preseason clinical assessment of dynamic balance, through a modified version of the YBT (mYBT), can predict risk of ROIs during one NCAA Division I cross-country (XC) season. Study Design Prospective case-control study Methods Participants from a Division I XC team were screened for mYBT performance in four directions: anterior (AN), posteromedial (PM), posterolateral (PL), and posterior (PO). ROIs were tracked over the course of the XC season. Receiver operating characteristic (ROC) curve analysis (α = 0.05) was utilized to investigate the effectiveness of the mYBT in predicting injury risk. Results Nine (5 female, 4 male) of 29 runners developed an ROI during the XC season. Five components of the mYBT were found to predict injuries, including normalized nondominant PO score (AUC = 0.756, p = 0.03; RR = 1.90), AN raw difference and limb asymmetry (AUC = 0.808, p = 0.01), and PM raw difference and limb asymmetry in males (AUC = 0.958, p = 0.02). Conclusion Specific components of the mYBT can help predict the risk of developing a running overuse injury over one Division I XC season. Level of Evidence Screening, Level 3 [ABSTRACT FROM AUTHOR]

Iliotibial band syndrome (ITBS) is a common injury that is related to running biomechanics. This study aimed to determine the gait characteristics that easily induce ITBS and explore the gait changes after the occurrence of ITBS. Thirty healthy male recreational runners participated in our study. Amongst them, 15 developed ITBS and comprised the ITBS group; the other 15 were healthy and comprised the control group. All participants underwent two gait trials, namely, before the first day of their running and after eight weeks, during which a force platform and a motion capture system collected biomechanical data. After running, the ITBS group exhibited greater anterior pelvic tilt and hip flexion angle than the control group. The ITBS group showed increased trunk inclination angle, whereas the control group demonstrated lower hip flexion, hip adduction angle and hip abductor moment than those at the beginning of running. Decreasing hip flexion, adduction angle and abductor moment may be a reasonable strategy to avoid the occurrence of ITBS. The occurrence of ITBS may be due to the lack of timely gait adjustment. Excessive trunk inclination and anterior pelvic tilt angle may be risks factor in the development of ITBS during running. [ABSTRACT FROM AUTHOR]

There is a sex bias for common overuse running injuries that are associated with sex-specific hip kinematics. Gait retraining programs aimed at altering hip kinematics may be more efficient if they incorporated an understanding of how hip kinematics are correlated with the movement of the remaining body segments. We applied a principal component analysis to structure the whole-body running kinematics of 23 runners (12 ♀) into k = 12 principal movements (PMk), describing correlated patterns of upper and lower body movements. We compared the time-dependent movement amplitudes with respect to each PMk between males and females using a waveform analysis and interpreted our findings according to stick figure animations. The movement amplitudes of two PMs (PM6 and PM8) showed statistically significant effects of “sex,” which were independent of running speed. According to PM8, females showed more hip adduction, which correlated with increased transverse rotation of the pelvis and upper body compared to men. We propose that increased hip adduction and upper body rotation in female runners may be a strategy to compensate for a less efficient arm and upper body swing compared to men. Gait interventions aimed at reducing hip adduction and running-related injuries in female runners should consider instructions for both upper and lower body to maximize training efficacy.

Dynamical systems theory suggests that studying the complexity of biological signals could lead to a single gait metric that reliably predicts risk of running-related injury (RRI). The purposes of this pilot study were to examine center of mass (COM) acceleration complexity at baseline, prior to RRI, and the change between timepoints between collegiate runners who developed RRI during a competitive season and those who remained uninjured, and to determine if complexity at these timepoints was associated with increased odds of RRI. Twenty-two collegiate runners from the same cross-country team wore a waist-mounted triaxial accelerometer (100 Hz) during easy-intensity runs throughout the competitive season. RRIs requiring medical attention were reported via an online survey. Control entropy was used to estimate the complexity of the resultant COM acceleration recorded during each run. Associations between complexity and RRI were assessed using a frequency-matching strategy where uninjured participants were paired with injured participants using complexity from the most time-proximal run prior to RRI. Seven runners sustained an RRI. No significant differences were observed between injured and uninjured groups for baseline complexity (p = 0.364, d = 0.405), pre-injury complexity (p = 0.258, d = 0.581), or change from baseline to pre-injury (p = 0.101, d = 0.963). There were no statistically significant associations found between complexity and RRI risk. Although no significant associations were found, the median effect from the models indicated that an increase in baseline complexity, pre-injury complexity, and change in complexity from baseline each corresponded to an increased odds of sustaining an RRI [baseline: odds ratio (OR) = 1.560, 95% CI = 0.587–4.143, p = 0.372; pre-injury: OR = 1.926, 95% CI: 0.689–5.382, p = 0.211; change from baseline: OR = 1.119; 95% CI: 0.839–1.491, p = 0.445). Despite non-significance and wide confidence intervals that included both positive and negative associations, the point estimates for >98% of the 10,000 frequency-case–control-matched model fits indicated that matching strategy did not influence the directionality of the association estimates between complexity and RRI risk (i.e., odds ratio >1.0). This pilot study demonstrates initial feasibility that additional research may support COM acceleration complexity as a useful single-metric monitoring system for RRI risk during real-world training. Follow-up work should assess longitudinal associations between gait complexity and running-related injury in larger cohorts.

Exertion may alter running mechanics and increase injury risk. Effects of exertion following gait-retraining are unknown. Objectives: To determine how exertion effects load rates, footstrike, and cadence in runners following a transition to forefoot strike (FFS) or increased cadence (CAD) gait-retraining. Methods: 33 (9 M, 24 F) healthy rearfoot strike runners were randomized into CAD or FFS groups. All runners received strengthening exercises and gait-retraining. 3D kinetic and kinematic motion analysis with instrumented treadmill at self-selected speed was performed at baseline & 1-week post-intervention, including an exerted run. Exertion was ≥17 on Borg's Rating of Perceived Exertion scale or voluntary termination of running. Results: Within group comparisons between fresh and exerted running: Cadence not affected in either group. Foot angle at contact became less plantarflexed in FFS (−2.2°, ±0.4) and was unchanged in CAD. Both groups increased vertical average load rate (FFS +16.9%, CAD +13.6%). CAD increased vertical stiffness (+8.6 kN/m). FFS reduced ankle excursion (1.8°). (p ≤ 0.05 for all values listed). Conclusion: Both FFS and CAD exhibited increased load rates with exertion. Variables that may have increased load rates were different for each group. CAD runners had increased vertical stiffness while FFS runners had reduced plantarflexion at contact and reduced ankle dorsiflexion excursion. [ABSTRACT FROM AUTHOR]

High loading impact associated with heel strikes causes running injuries. This study aimed to investigate how loading impact is affected by midsole hardness and running surface type. Twelve young rear-foot runners ran at a fixed speed along an 18 m runway wearing shoes with different midsole hardness (Asker C-45, C-50, C-55, C-60, from soft to hard) and on two different surfaces (rubber and concrete). We quantified vertical average loading rate (VALR) and vertical impact peak force (VIPF). We conducted midsole × surface repeated-measures ANOVA on loading impact measures, and one-sample t-tests to compare VALR with a threshold value (80 BW·s−1). Midsole hardness and surface type mainly affected VALR. Although no significant effect of these variables was observed for VIPF magnitude, there were effects on time to VIPF and steps with VIPF. Several combinations of midsole and surface hardness reduced VALR below 80 BW·s−1: Asker C-45 with both surfaces, and Asker C-50 with a rubber surface. The combination of softer midsole and surface effectively reduced loading rates as shown by increased time to VIPF and reduced VALR. Combining softer midsole and surface results in the greatest cushioning, which demonstrates the benefit of considering both factors in reducing running injuries. [ABSTRACT FROM AUTHOR]

Flatfoot is a common foot deformity, which could contribute to running injuries such as medial tibial stress syndrome. Intrafoot kinematics of flatfoot during walking have often been documented using multisegment foot models. However, the intrafoot kinematics of flatfoot during running remains unclear, despite the possible relationship between flatfoot and running injuries. We aimed to clarify rearfoot, midfoot, and forefoot kinematics when running in participants with normal foot and flatfoot. Participants with the normal foot (n = 14) and flatfoot (n = 14) were asked to runover‐ground at their preferred speed. Three‐dimensional kinematics of the rearfoot, midfoot, and forefoot during running were calculated based on the Rizzoli foot model. A two‐sample t‐test of statistical parametric mapping was performed to determine differences between normal foot and flatfoot in time histories of intrafoot kinematics during running. No differences were found between groups in characteristics and spatiotemporal parameters. In the frontal rearfoot angle, a significantly increased eversion from 24% to 100% (p <.001) was observed in the flatfoot compared to the normal foot. At the midfoot angle, a significantly increased eversion from 0% to 4% (p <.049) and 21% to 100% (p <.001) was observed in the flatfoot compared to the normal foot. At the forefoot angle, a significantly increased inversion from 6% to 17% (p <.047) was observed in the flatfoot compared to the normal foot. These findings may be useful to explain why flatfoot could contribute to running injuries such as medial tibial stress syndrome. [ABSTRACT FROM AUTHOR]

Background: Running-induced fatigue has received much attention in recent years. However, very few studies have investigated the effect of fatigue on lower limb biomechanics in three planes.Objective: This study was designed to investigate biomechanical changes in the lower limb in three planes following running-induced fatigue.Methods: Fifteen male novice runners were included in the study and performed three running trails pre- and post-fatigue. Wilcoxon signed-rank tests or paired-sample t tests were used to analyze the data.Results: Lower limb biomechanics significantly changed, especially kinetic parameters, when fatigue occurred. The peak ankle dorsiflexion angle and range of motion of the knee joint in the frontal plane increased. As for kinetic parameters, in the ankle joint, the peak external rotation moment, peak abduction power and peak internal rotation power increased. In the knee joint, the peak abduction and external rotation moment, peak flexion power, peak adduction and abduction power also increased. In the hip joint, the peak flexion moment was decreased, peak adduction and abduction moment, peak external rotation power, peak adduction and abduction power moment were increased.Conclusion: The findings of this study may contribute to our understanding of the impact of fatigue and provide some helpful information to prevent related injuries. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To investigate whether motion-control shoes reduce the risk of pronation-related injuries in recreational runners. DESIGN: Secondary analysis of a randomized controlled trial of the effect of shoes on running injuries. METHODS: Three hundred seventy-two recreational runners were randomized to receive either standard neutral or motion-control shoes and were followed up for 6 months regarding running activity and injury. Running injuries that occurred during this period were registered and classified as pronation-related injuries (Achilles tendinopathy, plantar fasciopathy, exercise-related lower-leg pain, and anterior knee pain) or other running-related injuries. With the use of competing risk analysis, the relationship between pronation-related and other running-related injuries and shoe type was evaluated by estimating the cause-specific hazard, controlling for other possible confounders like age, sex, body mass index, previous injury, and sport participation pattern. RESULTS: Twenty-five runners sustained pronation-related running injuries and 68 runners sustained other running-related injuries. Runners wearing the motion-control shoes had a lower risk of pronation-related running injuries compared with runners who wore standard neutral shoes (hazard ratio = 0.41; 95% confidence interval: 0.17, 0.98). There was no effect of shoe type (hazard ratio = 0.68; 95% confidence interval: 0.41, 1.10) on the risk of other running-related injuries. CONCLUSION: Motion-control shoes may reduce the risk of pronation-related running injuries, but did not influence the risk of other running-related injuries. [ABSTRACT FROM AUTHOR]

Introduction: Cross country is a popular high school and collegiate sport with a high rate of running-related injuries (RRI). Among high school runners, higher step rates have been associated with greater running experience and decreased body height, and lower step rates have been prospectively associated with increased risk of shin RRI. These associations have not been reported in collegiate cross country runners. The purpose of this study was to compare step rates between collegiate and high school cross country runners. Secondary objectives included determining if step rates in collegiate runners were related to experience and anthropometric variables, and whether their self-selected step rates were prospectively related to lower extremity RRI.Materials and methods: Twenty-nine NCAA Division III collegiate cross country runners (13 females, mean ± SD age 19.7 ± 1.3 years) completed a survey and ran at their self-selected speed. Step rate was assessed with Polar RCX5 wristwatches and S3+ Stride Sensors™ on the first day of the season. Runners were followed during the season for occurrence of time-loss lower extremity RRI. A cohort of 68 high school runners was used for comparison of step rates at their self-selected speeds.Results: Collegiate runners' self-selected step rates (177.1 ± 7.2 spm [steps per minute]) were higher than high school runners' (171.3 ± 8.3 spm) (p = 0.01). Collegiate runners ran at higher self-selected speeds (4.6 ± 0.5 m/s) than the high school runners (3.8 ± 0.5 m/s) (p < 0.001). A lower percentage of collegiate runners ran at ≤166 spm than high school runners. Body mass was negatively correlated with step rate in collegiate runners. During the season, 41.3% of collegiate runners experienced lower extremity RRI. Step rates for collegiate runners who did not experience RRI (178.9 ± 7.7 spm) were not significantly higher than runners who did experience RRI (174.5 ± 5.7 spm) (p = 0.10).Discussion: Higher step rates were found in collegiate than high school runners, but the difference was partially explained by higher self-selected running speeds. Thus, variations in step rate between high school and collegiate runners may be expected based on experience, speed, and body mass.

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. [ABSTRACT FROM AUTHOR]

PurposeTo investigate changes in hip and knee strength, kinematics, and running variability following two energy expenditure matched training runs; a medium intensity continuous run (MICR) and a high intensity interval training session (HIIT).MethodsTwenty (10 Females, 10 Males) healthy master class runners were recruited. Each participant completed the HIIT consisting of six repetitions of 800 m with a 1:1 work: rest ratio. The MICR duration was set to match energy expenditure of the HIIT session. Hip and knee muscular strength were examined pre and post both HIIT and MICR. Kinematics and running variability for hip and knee, along with spatiotemporal parameters were assessed at start and end of each run-type. Changes in variables were examined using both 2 × 2 ANOVAs with repeated measures and on an individual level when the change in a variable exceeded the minimum detectable change (MDC).ResultsAll strength measures exhibited significant reductions at the hip and knee (P < 0.05) with time for both run-types; 12% following HIIT, 10.6% post MICR. Hip frontal plane kinematics increased post run for both maximum angle (P < 0.001) and range of motion (P = 0.003). Runners exhibited increased running variability for nearly all variables, with the HIIT having a greater effect. Individual assessment revealed that not all runners were effected post run and that following HIIT more runners had reduced muscular strength, altered kinematics and increased running variability.ConclusionRunners exhibited fatigue induced changes following typical training runs, which could potentially present risk of injury development. Group and individual assessment revealed different findings where the use of MDC is recommended over that of P-values.

To explore whether homogeneous subgroups could be discriminated within a population of recreational runners with a running-related injury based on running kinematics evaluated with marker-based two-dimensional video analysis. Cross-sectional. Research laboratory. Fifty-three recreational runners (15 males, 38 females) with a running-related injury. Foot and tibia inclination at initial contact, and hip adduction and knee flexion at midstance were measured in the frontal and sagittal plane with marker-based two-dimensional video analysis during shod running on a treadmill at preferred speed. The four outcome measures were clustered using K-means cluster analysis (n = 2–10). Silhouette coefficients were used to detect optimal clustering. The cluster analysis led to the classification of two distinct subgroups (mean silhouette coefficient = 0.53). Subgroup 1 (n = 39) was characterized by significantly greater foot inclination and tibia inclination at initial contact compared to subgroup 2 (n = 14). The existence of different subgroups demonstrate that the same running-related injury can be represented by different kinematic presentations. A subclassification based on the kinematic presentation may help clinicians in their clinical reasoning process when evaluating runners with a running-related injury and could inform targeted intervention strategy development. • Two homogeneous subgroups were identified in runners with running-related injuries. • Foot and tibia inclination were significantly different between subgroups. • The same injury can be represented by different kinematic presentations. • Similar kinematic presentations can be related to different injuries. • Marker-based 2D video analysis can be used to assist clinical reasoning. [ABSTRACT FROM AUTHOR]

Supplemental digital content is available in the text. Purpose: To increase awareness of the need for coordinated medical care at 10-km races and to help direct future medical planning for these events. Methods: We related medical encounter data from nineteen 10-km road races to runner, race, and environmental characteristics. We quantified the most commonly used resources and described the disposition of runners in these encounters. Results: Across the 19 races and 90,265 finishers, there were 562 medical events for a cumulative incidence of 6.2 events per 1000 finishers (95% confidence interval, 5.7–6.8). Race size was associated with an increased incidence of medical events. Overall, the most common diagnosis was heat-related illness (1.6 per 1000 finishers), followed by musculoskeletal complaints (1.3 per 1000 finishers) and fluid–electrolyte imbalances (1.2 per 1000 finishers). For all diagnoses, runners with finishing times in the first performance quintile and in the fifth performance quintile had greater representation in the medical tent than mid-pack runners. Most runners were treated with supportive care, basic first aid, and oral rehydration. Ninety-four runners (1.0 per 1000 finishers) required ice water immersion for exertional heat stroke. There were low rates of hospital transport (0.2 per 1000 finishers), and no fatalities. Conclusions: In 10-km road races, injury rates are low compared with longer races in similar weather conditions. Common medical issues can be managed with basic resources in the on-site medical tent. Green flag start race conditions may not predict race safety with regard to exertional heat stroke risk. There were no deaths in nearly 100,000 finishers. [ABSTRACT FROM AUTHOR]

It is believed that human ancestors evolved the ability to run bipedally approximately 2 million years ago. This form of locomotion may have been important to our survival and likely has influenced the evolution of our body form. As our bodies have adapted to run, it seems unusual that up to 79% of modern day runners are injured annually. The etiology of these injuries is clearly multifactorial. However, 1 aspect of running that has significantly changed over the past 50 years is the footwear we use. Modern running shoes have become increasingly cushioned and supportive, and have changed the way we run. In particular, they have altered our footstrike pattern from a predominantly forefoot strike (FFS) landing to a predominantly rearfoot strike (RFS) landing. This change alters the way in which the body is loaded and may be contributing to the high rate of injuries runners experience while engaged in an activity for which they were adapted. In this paper, we will examine the benefits of barefoot running (typically an FFS pattern), and compare the lower extremity mechanics between FFS and RFS. The implications of these mechanical differences, in terms of injury, will be discussed. We will then provide evidence to support our contention that FFS provides an optimal mechanical environment for specific foot and ankle structures, such as the heel pad, the plantar fascia, and the Achilles tendon. The importance of footwear will then be addressed, highlighting its interaction with strike pattern on mechanics. This analysis will underscore why footwear matters when assessing mechanics. Finally, proper preparation and safe transition to an FFS pattern in minimal shoes will be emphasized. Through the discussion of the current literature, we will develop a justification for returning to running in the way for which we were adapted to reduce running-related injuries.

Context: Before examining the impact of training load on injury risk in runners, it is important to gain insight in the differences between methods that are used to measure change in training load., Objective: To investigate differences between four methods to calculate 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 averages (EWMA)., Design: Descriptive epidemiology study., Setting: 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 GPS training data., Participants: Runners who registered for running events (distances 10-42.195 kilometers) in the Netherlands., Main Outcome Measures: 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., Results: 430 participants (73.3% men; age 44.3 years) shared their GPS training data with in total 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 increase in training load. Of the training sessions with significant increase in training load, 43.0% expressed in the weekly training load method showed a difference with the coupled RA and EWMA method. Training sessions with significant increase in training load based on the coupled RA method showed 100% overlap with the uncoupled RA and EWMA method., Conclusions: The difference in 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 RRI risk is needed.

Study Design: Repeated measures Background: Both clinicians and researchers often utilize treadmills to analyze spatiotemporal and biomechanical factors during running. However, there is question of whether or not treadmill running mimics overground running. The development of new wearable technology, such as pressure sensor insoles, presents an opportunity to compare the two running conditions. Purpose: To compare the spatiotemporal factors between overground and treadmill running in collegiate runners, using pressure sensor insoles. Methods: Twenty-one collegiate runners (age 20.1 ± 1.5 years, 81% female) were recruited from a Division I Cross Country team. Subjects participated in two 15-minute testing sessions. During the first session, subjects ran at their "easy run pace" for 200 meters, while wearing pressure sensor insoles. During the second session, subjects ran at a speed-matched pace on a treadmill for one minute at a level grade, and one minute at a 1% incline. Cadence, stance duration and swing duration were processed using Moticon Science Pro+ software (Munich, DE). Data between overground and treadmill running was compared using repeated measures analysis of variance with α = 0.05. Results: Compared to overground running, level and incline treadmill running was associated with increased cadence (mean difference [MD]=3.55-3.22 strides per minute; p< 0.01), decreased stance duration (MD=14-16 ms; p< 0.01), and decreased swing duration (MD=11-12 ms; p< 0.05). Conclusion: In collegiate runners, overground and treadmill running differ in spatiotemporal comparisons. Levels of Evidence: 3 [ABSTRACT FROM AUTHOR]

BACKGROUND Runners experience a high proportion of overuse injuries, with extended recovery periods involving a gradual, progressive return to preinjury status. A running-specific patient-reported outcome (PRO) measure does not exist, and a questionnaire assessing critical elements of runners' recovery processes may have excellent psychometric properties. OBJECTIVES To develop a valid, reliable, and responsive evaluative PRO measure to assess longitudinal change in running ability after running-related injury (RRI) for clinical practice and research applications. METHODS Self-identified runners and selected experts participated in an iterative, 6-step development process of the University of Wisconsin Running Injury and Recovery Index (UWRI) in this longitudinal clinical measurement study. Content-related validity was assessed using open comments. Reproducibility was assessed using Cronbach's alpha, the intraclass correlation coefficient (ICC), and standard error of measurement (SEM). An anchor-based construct validity assessment measured the association between the change in UWRI score and global rating of change (GROC). Responsiveness assessments included floor and ceiling effects. RESULTS The 9-item UWRI assesses running ability following an RRI, with the maximum score of 36 indicating a return to preinjury running ability. The UWRI demonstrated acceptable internal consistency (α = .82), test-retest reliability (ICC = 0.93), and SEM (1.47 points). Change in UWRI score was moderately correlated with the GROC (r = 0.61; 95% confidence interval: 0.4, 0.76). Floor and ceiling effects were absent. Completion required 3 minutes 15 seconds. CONCLUSION The UWRI is a reliable PRO measure and is responsive to changes in running function following an RRI, with minimal administrative burden. LEVEL OF EVIDENCE Therapy, level 2c [ABSTRACT FROM AUTHOR]

The current literature on footwear cushioning and pronation has suggested that there may not be a relationship between chronic injury risk and these parameters based on mixed findings and lack of evidence of an association with prospective injury rates. Since footwear has been designed and developed based on cushioning and pronation, we suggest that we have possibly been on a misguided path in footwear design for the last few decades. Current thought thus implies that a new method of footwear prescription is necessary if we are to guide runners toward appropriate footwear that accommodates their individual biomechanical patterns during running. Based on a series of studies investigating the response of the leg to movement and loading patterns, we developed a novel paradigm based on Nigg's 'preferred movement path'. The assumptions of the 'preferred motion path' were modified in the new method and refined as the 'habitual motion path'. We focused on knee motion in addition to foot and ankle motion since the greatest number of injuries to runners is at the knee. We utilized a kinematic method for developing a calculation to determine the deviation of a runner's joint motion path during running from their habitual motion path. We used this deviation as an index for the individual prescription of an appropriate running shoe. While this new method matches a runner based only on their biomechanics, there are other factors that need to be considered. For example, in footwear selection, the individual's training and injury history in addition to the experience that the runner is seeking from their run must also be considered. [ABSTRACT FROM AUTHOR]

• Coordination variability is a critical index for defining potential risk of injury. • SPM showed no significant differences in coordination variability between gender. • Variability may not be associated with gender difference of knee incidence rate. Female recreational runners are 2–3 times more likely to suffer from knee injury compared with male runners. However, the exact reason for this gender difference regarding knee injury remains unclear. Our study aimed to investigate gender differences in coordination variability between shank and rearfoot during running using statistical parametric mapping (SPM). Eleven healthy males and eleven healthy females ran on a treadmill. A modified vector coding technique procedure was used to create joint coupling between shank internal/external rotation and rearfoot eversion/inversion. The standard deviation of each coupling was computed as a measure of coordination variability during the stance phase. All trajectory data of coordination variability between genders were analyzed using a two-sample t -test of SPM. No differences in the normalized spatiotemporal parameters of speed, cadence and step length were found between males and females. SPM showed no significant differences between the genders in coordination variability. This study demonstrated that coordination variability between the shank and rearfoot during running may not be associated with the different incidence rates of knee injuries among male and female participants. [ABSTRACT FROM AUTHOR]

Supplemental digital content is available in the text. Running is a popular activity that results in high rates of overuse injury, with less-experienced runners becoming injured at higher rates than their more-experienced peers. Although measures of joint kinematics and kinetics and ground reaction forces have been associated with overuse running injuries, similar differences across levels of running experience have not been found. Because running is a motor skill that may develop with experience, an analysis of segment coordination and its variability could provide additional insight into why injury incidence decreases with increasing experience. Purpose: The purpose of this study was to determine if less-experienced runners have different segment coordination and lower segment coordination variability compared with their more-experienced peers. Methods: This retrospective analysis included 20 more-experienced (≥10 yr running) and 21 less-experienced (≤2 yr running) runners. Sagittal thigh versus shank and shank versus foot segment coordination and coordination variability were calculated using a modified vector coding approach as individuals ran on a treadmill at preferred pace. Coordination and its variability were compared between groups during terminal swing and early, mid, and late stance for both segment couples. Results: Segment coordination was similar between less- and more-experienced runners. Less-experienced runners had lower segment coordination variability compared with more-experienced runners for both the thigh versus shank and shank versus foot couples. This lower variability occurred during early and mid stance. Conclusions: Runners appeared to attain stable segment coordination patterns within 2 yr of consistent running, but had lower coordination variability compared with individuals who had been running for 10 or more years. These results suggest that assessment of movement patterns and their flexibility may help inform injury prevention or treatment strategies for less-experienced runners. [ABSTRACT FROM AUTHOR]

BACKGROUND: Overweight and obese novice runners are subjected to a higher load per stride than their normal-weight peers. Do they reduce their running dose accordingly when beginning a self-chosen running regime? OBJECTIVES: To describe and compare the preferred running dose in normal-weight, overweight, and obese novice runners when they commence a self-chosen running regime. METHODS: In this exploratory, 7-day prospective cohort study, 914 novice runners were categorized into 1 of 3 exposure groups, based on their body mass index (BMI): (1) normal weight (BMI less than 25 kg/m², n = 405; reference group), (2) overweight (BMI of 25 to less than 30 kg/m², n = 341), and (3) obese (BMI of 30 kg/m² or greater, n = 168). All runners were equipped with a global-positioning- system running watch, which provided information about distance, duration, speed, and date of each running session during the first week of a self-chosen running regime. RESULTS: During the first session, overweight runners (difference, -0.5 km/h; 95% confidence interval [Cl]: -0.8, -0.2 km/h; P<.05) and obese runners (-1.7 km/h; 95% Cl: -2.0, -1.4 km/h; P<. 05) ran slower than normal-weight runners. Obese runners also ran a shorter distance compared to normal-weight runners (-0.4 km; 95% Cl: -0.7, -0.2 km; P<.05). During the first week, overweight runners (-0.5 km/h; 95% Cl: -0.7, -0.2 km/h; P<. 05) and obese runners (-1.7 km/h; 95% Cl: -2.0, -1.4 km/h; P<.05) ran slower than normal-weight runners, while running distance and duration were similar. CONCLUSION: Overweight and obese runners selected a similar training dose to that of normal-weight runners when starting a self-chosen running regime. This may partly explain the higher running-injury risk among overweight and obese runners compared with normal-weight runners observed by other studies. [ABSTRACT FROM AUTHOR]

The free moment is considered an important variable during running in lower extremity transverse plane loading of the support leg. The effect of current footwear technology on free moment application has not been widely studied despite evidence that greater free moment amplitudes may be related to common lower extremity overuse injuries. Therefore, the purpose of this study was to determine the effect of current running shoe types on the free moment application in running and to identify which design features specifically influence free moment waveforms. The free moments and lower extremity kinematics of 103 recreational runners were collected when running at 3.5 m/s using force plates embedded in the ground. Six conditions were analysed, ranging from minimalistic to motion-control footwear. Runners were classified into three groups of different free moment pattern using functional principal component and cluster analysis techniques. The results revealed that the free moment application can be affected by footwear technologies used in modern running shoes. Nonetheless, the free moment application was influenced to a greater extent by the overall running technique highlighted by the greater effect sizes for pattern membership compared to footwear effects. Footwear may affect the free moment application as a function of its torsional flexibility and to a lesser extent by means of motion-control features. Future studies should address the effect of footwear design features (such as shoe-mass and traction) on free moment application in greater detail to improve the running style with respect to injury prevention and performance enhancement. [ABSTRACT FROM PUBLISHER]

Introduction: There is a need for an ecological and complex systems approach for better understanding the development and prevention of running-related injury (RRI). In a previous article, we proposed a prototype model of the Australian recreational distance running system which was based on the Systems Theoretic Accident Mapping and Processes (STAMP) method. That model included the influence of political, organisational, managerial, and sociocultural determinants alongside individual-level factors in relation to RRI development. The purpose of this study was to validate that prototype model by drawing on the expertise of both systems thinking and distance running experts.Materials and Methods: This study used a modified Delphi technique involving a series of online surveys (December 2016- March 2017). The initial survey was divided into four sections containing a total of seven questions pertaining to different features associated with the prototype model. Consensus in opinion about the validity of the prototype model was reached when the number of experts who agreed or disagreed with survey statement was ≥75% of the total number of respondents.Results: A total of two Delphi rounds was needed to validate the prototype model. Out of a total of 51 experts who were initially contacted, 50.9% (n = 26) completed the first round of the Delphi, and 92.3% (n = 24) of those in the first round participated in the second. Most of the 24 full participants considered themselves to be a running expert (66.7%), and approximately a third indicated their expertise as a systems thinker (33.3%). After the second round, 91.7% of the experts agreed that the prototype model was a valid description of the Australian distance running system.Conclusion: This is the first study to formally examine the development and prevention of RRI from an ecological and complex systems perspective. The validated model of the Australian distance running system facilitates theoretical advancement in terms of identifying practical system-wide opportunities for the implementation of sustainable RRI prevention interventions. This 'big picture' perspective represents the first step required when thinking about the range of contributory causal factors that affect other system elements, as well as runners' behaviours in relation to RRI risk. [ABSTRACT FROM AUTHOR]

Background The metatarsal bones of the foot are particularly susceptible to stress fracture owing to the high strains they experience during the stance phase of running. Shoe cushioning and stride length reduction represent two potential interventions to decrease metatarsal strain and thus stress fracture risk. Methods Fourteen male recreational runners ran overground at a 5-km pace while motion capture and plantar pressure data were collected during four experimental conditions: traditional shoe at preferred and 90% preferred stride length, and minimalist shoe at preferred and 90% preferred stride length. Combined musculoskeletal – finite element modeling based on motion analysis and computed tomography data were used to quantify metatarsal strains and the probability of failure was determined using stress-life predictions. Findings No significant interactions between footwear and stride length were observed. Running in minimalist shoes increased strains for all metatarsals by 28.7% (SD 6.4%; p < 0.001) and probability of failure for metatarsals 2–4 by 17.3% (SD 14.3%; p ≤ 0.005). Running at 90% preferred stride length decreased strains for metatarsal 4 by 4.2% (SD 2.0%; p ≤ 0.007), and no differences in probability of failure were observed. Interpretations Significant increases in metatarsal strains and the probability of failure were observed for recreational runners acutely transitioning to minimalist shoes. Running with a 10% reduction in stride length did not appear to be a beneficial technique for reducing the risk of metatarsal stress fracture, however the increased number of loading cycles for a given distance was not detrimental either. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background Iliotibial band syndrome is a common overuse running injury which results in altered mechanics. While injuries alter discrete mechanics, they may also cause a change in coordination variability, the stride-to-stride organization of runners' movement patterns. Uninjured and injured runners may experience a change in coordination variability during a run to exertion due to fatigue, pain, or a combination of these factors. The aim of the current study was to determine if runners with iliotibial band syndrome and uninjured runners display different segment coordination variability across the course of a run to exertion. Methods 3D kinematics were collected as 13 uninjured runners and 12 runners with iliotibial band syndrome ran on a treadmill. A modified vector coding technique was used to calculate coordination variability during stance for segment couples of interest. Coordination variability was compared between uninjured and injured runners at the beginning and end of the run. The influence of pain on coordination variability was also examined. Findings There were no differences in coordination variability at the beginning or end of the run between uninjured runners and those with iliotibial band syndrome. The change in coordination variability due to the run was not different between uninjured runners, injured runners who experienced no change in pain, and injured runners who did experience a change in pain. Interpretation Runners do not constrain the patterns of segment motion they use in response to exertion nor does it appear that occurrence of pain during running results in a differential change in coordination variability. [ABSTRACT FROM AUTHOR]

Background: Behavioral science methods have rarely been used in running injury research. Therefore, the attitudes amongst runners and their coaches regarding factors leading to running injuries warrants formal investigation. Purpose: To investigate the attitudes of middle- and long-distance runners able to compete in national championships and their coaches about factors associated with running injury development. Methods: A link to an online survey was distributed to middle- and long-distance runners and their coaches across 25 Danish Athletics Clubs. The main research question was: "Which factors do you believe influence the risk of running injuries?". In response to this question, the athletes and coaches had to click "Yes" or "No" to 19 predefined factors. In addition, they had the possibility to submit a free-text response. Results: A total of 68 athletes and 19 coaches were included in the study. A majority of the athletes (76% [95%CI: 66%; 86%]) and coaches (79% [95%CI: 61%; 97%]) reported "Ignoring pain" as a risk factor for running injury. A majority of the coaches reported "Reduced muscle strength" (79% [95%CI: 61%; 97%]) and "high running distance" (74% [95%CI: 54%; 94%]) to be associated with injury, while half of the runners found "insufficient recovery between running sessions" (53% [95%CI: 47%; 71%]) important. Conclusion: Runners and their coaches emphasize ignoring pain as a factor associated with injury development. The question remains how much running, if any at all, runners having slight symptoms or mild pain, are able to tolerate before these symptoms develop into a running-related injury. Level of Evidence: 3b [ABSTRACT FROM AUTHOR]

The popularity of running as a form of exercise continues to increase dramatically worldwide. Alongside this participation growth is the burden of running-related injury (RRI). Over the past four decades, traditional scientific research applications have primarily attempted to isolate discrete risk factors for RRI using observational study designs as commonly used in public health epidemiology. Unfortunately, only very few randomised controlled trials have evaluated the efficacy associated with a well-specified RRI prevention intervention. Even though the knowledge about risk factors as generated in observational studies is valuable for better understanding why RRI develops, it nonetheless means that there remains a major knowledge gap about how best to prevent it, especially in a way that fully addresses all causal factors. Alongside the continuing use of traditional scientific approaches, a particular systems ergonomics methodology should also be considered in light of its potential to visualise the complete distance running system. This article adapts the Systems Theoretic Accident Mapping and Processes (STAMP) model to the RRI research prevention context. The direct application of STAMP might offer new knowledge about how to prevent RRI, such as exposing questions around the feasibility of adopting novel injury prevention interventions that do not directly target runners themselves. [ABSTRACT FROM PUBLISHER]

It is believed that human ancestors evolved the ability to run bipedally approximately 2 million years ago. This form of locomotion may have been important to our survival and likely has influenced the evolution of our body form. As our bodies have adapted to run, it seems unusual that up to 79% of modern day runners are injured annually. The etiology of these injuries is clearly multifactorial. However, 1 aspect of running that has significantly changed over the past 50 years is the footwear we use. Modern running shoes have become increasingly cushioned and supportive, and have changed the way we run. In particular, they have altered our footstrike pattern from a predominantly forefoot strike (FFS) landing to a predominantly rearfoot strike (RFS) landing. This change alters the way in which the body is loaded and may be contributing to the high rate of injuries runners experience while engaged in an activity for which they were adapted. In this paper, we will examine the benefits of barefoot running (typically an FFS pattern), and compare the lower extremity mechanics between FFS and RFS. The implications of these mechanical differences, in terms of injury, will be discussed. We will then provide evidence to support our contention that FFS provides an optimal mechanical environment for specific foot and ankle structures, such as the heel pad, the plantar fascia, and the Achilles tendon. The importance of footwear will then be addressed, highlighting its interaction with strike pattern on mechanics. This analysis will underscore why footwear matters when assessing mechanics. Finally, proper preparation and safe transition to an FFS pattern in minimal shoes will be emphasized. Through the discussion of the current literature, we will develop a justification for returning to running in the way for which we were adapted to reduce running-related injuries. [ABSTRACT FROM AUTHOR]

Chronic Achilles tendinopathy (AT) is an overuse condition seen among runners. Eccentric exercise can decrease pain and improve function for those with chronic degenerative tendon changes; however, some individuals have continued pain requiring additional intervention. While joint mobilization and manipulation has not been studied in the management in Achilles tendinopathy, other chronic tendon dysfunction, such as lateral epicondylalgia, has responded well to manual therapy (MT). Three runners were seen in physical therapy (PT) for chronic AT. They were prescribed eccentric loading exercises and calf stretching. Joint mobilization and manipulation was implemented to improve foot and ankle mobility, decrease pain, and improve function. Immediate within-session changes in pain, heel raise repetitions, and pressure pain thresholds (PPT) were noted following joint-directed MT in each patient. Each patient improved in self-reported function on the Achilles tendon specific Victorian Institute for Sport Assessment questionnaire (VISA-A), pain levels, PPT, joint mobility, ankle motion, and single-leg heel raises at discharge and 9-month follow-up. The addition of MT directed at local and remote sites may enhance the rehabilitation of patients with AT. Further research is necessary to determine the efficacy of adding joint mobilization to standard care for AT. Level of Evidence: Case series. Therapy, Level 4. [ABSTRACT FROM PUBLISHER]

Objectives: To examine the effects of shoe type and stride length reduction on lower-extremity running mechanics and cumulative loading.Design: Within-subject with four conditions: (1) control shoe at preferred stride length; (2) control shoe at 90% preferred stride length; (3) minimalist shoe at preferred stride length; (4) minimalist shoe at 90% preferred stride length.Methods: Fourteen young healthy males ran overground at their preferred speed while motion capture, force platform, and plantar pressure data were collected. Peak moments, impulse, mechanical work, and cumulative impulse were calculated at the metatarsophalangeal, ankle, and knee joint, and compared between conditions using a 2×2 factor repeated measures ANOVA.Results: In general, running in minimalist footwear increased measures of loading at the metatarsophalangeal joint and ankle joint (mean increases of 7.3% and 5.9%, respectively), but decreased measures of loading at the knee (mean decrease of 7.3%). Conversely, running with reduced stride length decreased single-stance measures of loading at the ankle and knee joint (ranging from -0.9% to -20.5%), though cumulative impulse was higher at the ankle and lower at the knee.Conclusions: Running in minimalist shoes increased loads at the metatarsophalangeal and ankle joint, which may explain some of the incidence of overuse injuries observed in minimalist shoe users. Decreased ankle loads at 90% preferred stride length were not necessarily sufficient to reduce cumulative loads when impulse and loading cycles were weighted equally. Knee loads decreased more when running at 90% preferred stride length (16.2% mean reduction) versus running in a minimalist shoe (7.3% mean reduction), but both load reduction mechanisms appeared to have an additive effect (22.2% mean reduction). [ABSTRACT FROM AUTHOR]