The aim of this prospective study was to investigate differences in participant characteristics, previous injury, running dynamics during a long-distance run, and training between injured and uninjured runners in runners of different abilities. Center-of-mass acceleration data were collected during a long-distance overground run. Runners were then divided into four groups (elite, advanced, intermediate and slow) based on their finishing time. Participants completed training diaries and were monitored for 1 year. Seventy-six runners completed the prospective study with 39 (51.3%) sustaining a running injury (44% elite, 42% advanced, 54% intermediate, 59% slow). Differences between injured and uninjured runners within each group related to injury included: (1) elite injured runners ran with longer contact times and (2) more slow injured runners reported an injury in previous year, were heavier, had higher body mass and body mass index, ran with lower step frequencies, and ran a greater weekly distance. Advanced injured runners exhibited fatigue changes in step regularity and peak braking during the run that may be related to injury. These findings suggest that runners of different abilities may have different factors related to injury however due to the small sample sizes in the groups this needs to be explored further.

Background: Because of the complex and multifaceted nature of running injuries, a multifactorial approach when investigating running injuries is required. Hypothesis: Compared with uninjured runners, injured runners would exhibit different running biomechanics, display more fatigue changes, and would run a greater weekly running volume; more injured runners would also report having a previous injury. Study Design: Prospective cohort study. Level of Evidence: Level 4. Methods: At commencement of the study, data were collected on demographics, anthropometrics, training history, previous injury history, and center-of-mass accelerations during a long-distance overground run. Participants completed weekly training diaries and were monitored for 1 year for an injury. Results: A total of 76 runners completed the study, with 39 (22 male; 17 female) reporting an injury. Compared with male uninjured runners, male injured runners were heavier and ran a greater weekly distance. Male runners (injured and uninjured) exhibited increases in mediolateral center-of-mass accelerations during the run. Compared with female uninjured runners, female injured runners were heavier, ran with longer flight times and lower step frequencies, and more of them had reported an injury in the previous year and had increased speed training in the weeks prior to injury. Over 60% of male injured runners and over 50% of female injured runners had increased their weekly running distance by >30% between consecutive weeks at least once in the 4 weeks prior to injury. Conclusion: Factors that may be related to injury for male runners include being heavier, running a greater weekly distance, and exhibiting fatigue changes in mediolateral center-of-mass accelerations. Factors that may be related to injury for female runners include being heavier, having an injury in the previous year, running with longer flight times and lower step frequencies, and increasing speed training prior to injury. Increases in weekly running distance in 1 consecutive week (particularly >30%) needs to be monitored in training, and this along with the other factors found may have contributed to injury development. Clinical Relevance: This study found that multiple factors are related to running injuries and that some factors are sex specific. The findings can aid in injury prevention and management.

Journal of Physical Fitness, Medicine & Treatment in Sports is an interdisciplinary open access peer reviewed journal that publishes original research, reviews, short communication, case reports, news, commentaries etc., in the field of sports medicine, treatment and exercise medication.

Objective: The aim of this study was to assess for fatigue related changes in center-of-mass (COM) acceleration during a prolonged overground run in a group of healthy male runners using a tri-axial accelerometer attached to a runner’s low back. Methods: Thirty healthy male runners’ performed an eight kilometer (20 laps) overground time trial paced run on a 400 meter athletics track. Kinematic measures assessed regularly throughout the run included signal energy and acceleration impulse in the anteroposterior (AP), mediolateral (ML) and vertical (VT) directions, contact time (CT) and step frequency. A repeated measures analysis of variance comparing each data collection point to the initial was used to identify fatigue related changes. Results: Compared to initial measurement, CT significantly increased during laps six to 18 in addition to significant increases in ML signal energy and decreases in AP impulse identified from lap four to 20. Conclusion: A tri-axial accelerometer was able to identify changes in ML and AP COM acceleration measures plus a runner’s CT indicating fatigue was impacting a runner throughout a prolonged run. Limited changes in VT acceleration measures were identified suggesting biomechanical fatigue related running changes predominately occur in the horizontal plane. Future research investigating the effects of fatigue on running should use frequent and regular data collection to identify fatigue related running changes.

Background: The hamstring muscles are regularly injured during high risk sports involving sprinting and kicking activities. Currently there is inconclusive evidence regarding hamstring muscle length measurements as a predictor for hamstring injury using the active knee extension test. A more functional hamstring flexibility test may be a better measure of hamstring muscle length compared to the active knee extension test as it more closely represents the position of the hamstrings during high risk activities. Purpose: The aim of this study was to compare hamstring muscle length measurements determined using the traditional the active knee extension test and newly proposed functional hamstring flexibility test. Study Design: Comparative single group cohort study. Methods: Thirty seven healthy males aged 18-40 years currently involved in rugby union, Australian football, soccer or sprinting were included in the study. Hamstring muscle length was measured using the active knee extension test and the functional hamstring flexibility test on both right and left legs. Results: The functional hamstring flexibility test measured a significantly smaller knee extension angle (p<0.001) compared to the active knee extension test. Conclusion: A functional position such as that in the functional hamstring flexibility test results in a significantly smaller measure of knee extension than a non-functional assessment position, such as the active knee extension test.

INTRODUCTION: Understanding kinematic and kinetic changes with fatigue during running is important to assess changes that may influence performance and injury. The aim of this systematic review was to identify, critique and summarize literature about the effects of fatigue on kinematics and kinetics during a fatiguing overground run and present the reported influence on performance and injury.EVIDENCE ACQUISITION: An electronic search was conducted of MEDLINE, SPORTDiscus, CINAHL and PubMed databases. Two reviewers assessed articles for inclusion, and evaluated the quality of articles included using a modified version of the Downs and Black Quality Index.EVIDENCE SYNTHESIS: A total of twelve articles were identified for review. The mean quality assessment score was seven out of a possible 12. Kinematic and kinetic changes reported to affect performance included decreased speed, step or stride frequency and length, increased trunk flexion, lower leg position at heel strike, mediolateral acceleration, changes in hip and knee ranges, and decreased stride regularity, heel lift, maximum knee rotation and backward ankle velocity. Alterations reported to increase risk of injury included decreased step frequency, increased upper body rotation and lower leg position at heel strike, and decreased knee flexion during stance. Reduced risk of injury has been linked to decreased step length and hip ranges, and increased trunk flexion.CONCLUSIONS: This review found limited evidence regarding changes in kinematic and kinetic during a fatiguing run in relation to performance and injury. Higher quality studies are warranted, with a larger sample of homogenous runners, and type of run carefully selected to provide quality information for runners, coaches and clinicians.

Introduction: The purpose of this study was to validate acceleration data from a single inertial sensor containinga tri-axial accelerometer, whilst running overground during a prolonged run against a motion analysis system. Methods: An inertial sensor was placed on the low back of 10 runners who performed an 8 km run on a treadmill.To provide validation of the sensor, data were collected as runners ran along a runway through a motion analysis system at the beginning and throughout the run.Results: High levels of agreement between the two systems were found in the craniocaudal and mediolateral acceleration, with antero posterior having the least agreement with greatest Typical Error of the Estimate (0.66 sample points). Very high to extremely high correlations across all testing times were found in all three directions of accelerations (r=0.75 to 0.95). Heel strike and toe off events were identified in anteroposterior and craniocaudal acceleration, with high levels of agreement and extremely high correlations (r=0.99) between the two systems.Minimal variation and change in agreement and correlation between the data at each testing time were found. Discussion: This study provides evidence that a single inertial sensor placed on the low back is valid for measuring three-dimensional acceleration in overground running during a prolonged run. Further analysis identified specific events of heel strike and toe off and were comparable between the two systems. The minimal variation and change in agreement between the two systems during the run indicates the adherence method of the inertial sensor was suitable. Conclusions: The results of this study indicate that data collected from a single inertial sensor is highly correlated with simultaneous data collected using a motion analysis system, and has the capability to identify heelstrike and toe off events in overground running throughout a prolonged fatiguing run.

BACKGROUND: The relationship between low back pain (LBP) and reduced hip rotation has been well established. However, there is a lack of studies investigating the effect of treatment targeted at the hip in people with LBP.OBJECTIVE: The aim of this study was to assess the level of effectiveness that different types of exercises targeted at the hip had on pain and function in individuals with non-specific chronic or recurrent LBP with concurrent reduced hip rotation.METHOD: Thirty participants were assigned to one of three exercise groups: hip rotation stretching, multi-directional hip stretching and hip strengthening. All groups participated in a six week home exercise program. Pain (numerical rating scale), functional disability (Modified Oswestry Disability Questionnaire; MOD), and hip rotation measurements were assessed at baseline and post intervention.RESULTS: Results revealed that all exercise groups were effective in improving pain and function (MOD) (P < 0.05). Between group comparisons revealed that hip strengthening was more effective than hip rotation exercises in improving functional disability (P = 0.03). The majority of participants in all groups (60-70%) demonstrated clinical improvements in pain, but only the hip strengthening group had the majority of participants (80%) exhibit clinical improvements in function.CONCLUSION: In individuals with non-specific LBP and reduced hip rotation, clinical intervention of providing exercises targeted at the hip can be beneficial in improving pain and function, with strengthening exercises most beneficial for improving function.