A prospective study on time to recovery in 254 injured novice runners

Prediction of running-induced Achilles tendinopathy with pain sensitivity - a 1-year prospective study

Background and aims Achilles tendinopathy is common among runners, but the etiology remains unclear. High mechanical pain sensitivity may be a predictor of increased risk of developing Achilles tendinopathy in this group. The purpose of this study was to investigate whether local pain sensitivity could predict the development of Achilles tendinopathy in recreational male runners. The overall hypothesis was that high pain sensitivity would be related to a higher risk of developing Achilles tendinopathy among recreational male runners. Methods Ninety-nine recreational male runners were recruited and followed prospectively for 1 year. At baseline and after 500 km of running the pressure pain threshold (PPT) was assessed at the infraspinatus and at the Achilles tendon (AT-PPT). Based on the AT-PPT at baseline, a median split was used to divide the runners into two groups. The high pain sensitivity groups was defined as runners displaying a pain pressure threshold below 441 kPa on the Achilles tendon, while the low pain sensitivity group was defined as runners displaying a pain pressure threshold above 441 kPa on the Achilles tendon, respectively. Subsequently, the cumulative risk difference between the two groups was assessed by using the pseudo-observation method. Results High pain sensitivity runners sustained 5%-point (95% CI: -0.18 to 0.08) more Achilles tendinopathy episodes during the first 1,500 km. No significant group differences in risk were found at 100, 250, 500, 1,000 and 1,500 km of running. Conclusions No significant association was found between mechanical pain sensitivity in the Achilles tendon and the risk of developing Achilles tendinopathy. However, the risk difference indicated a association between a high mechanical pain sensitivity and an increased risk of developing Achilles tendinopathy. It is plausible that changes in pain sensitivity were masked by unmeasured covariates, such as the differences in progression/regression of training volume and running speed between the two groups. This study was limited in size, which limited the possibility to account for covariates, such as differences in progression/regression of running speed between runners. With the limitations in mind, future studies should control the training volume, speed and running shoes in the design or account for it in the analysis. Implications Pain sensitivity of the Achilles tendon seems not to be related to an increased risk of developing Achilles pain in relation to running.

THE START-TO-RUN DISTANCE AND RUNNING-RELATED INJURY AMONG OBESE NOVICE RUNNERS: A RANDOMIZED TRIAL

BACKGROUND/PURPOSE

High body mass index is associated with an increased risk of running-related injury among novice runners. However, the amount of running participation plays a fundamental explanatory role in regards to running-related injury development. Therefore, the purpose of the present study was to investigate if the risk of running-related injury among obese novice runners (BMI 30-35) was different when the start-to-run distance was 3km per week instead of 6km per week.

HYPOTHESIS

A start-to-run distance of 3km per week is associated with 20% fewer running-related injuries and significantly fewer symptoms of overuse injury than a start-to-run distance of 6km per week among obese novice runners.

STUDY DESIGN

Randomized trial.

METHODS

Fifty-six obese novice runners with a body mass index between 30-35 were enrolled and randomized to receive one of the two following Interventions: (i) a 4-week running program with a start-to-run distance of 3km per week including three sessions with 1km running per session (n=29), or (ii) a 4-week running program with a start-to-run distance of 6km per week including three sessions with 2km running per session (reference group, n=27). In both programs, the weekly running distance was increased by 10% each week throughout the follow-up.

RESULTS

The intention-to-treat analysis revealed a protective cumulative risk difference of -16.3% (95%CI: -43.8%; 11.3%, p=0.25) after four weeks. Importantly, some participants completed much more running than prescribed (n=5) and some never uploaded any training (n=15). Therefore, a supplementary per-protocol analysis was performed revealing a cumulative risk difference of -31.2% (95%CI: -57.0%; -5.2%, p=0.02) after four weeks. Furthermore, in the per-protocol analysis, the cumulative risk difference of overuse-injury symptoms was -47.8% (95%CI: -81.0%; -14.6%, p=0.01) after four weeks of running.

CONCLUSIONS

A 3km reduction from 6km per week to 3km per week in the start-to-run distance appears to be associated with fewer running-related injuries and significantly fewer symptoms of overuse injury.

LEVEL OF EVIDENCE

2b.

How Do Novice Runners With Different Body Mass Indexes Begin a Self-chosen Running Regime?

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 [CI]: -0.8, -0.2 km/h; P<.05) and obese runners (-1.7 km/h; 95% CI: -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% CI: -0.7, -0.2 km; P<.05). During the first week, overweight runners (-0.5 km/h; 95% CI: -0.7, -0.2 km/h; P<.05) and obese runners (-1.7 km/h; 95% CI: -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. J Orthop Sports Phys Ther 2018;48(11):873-877. Epub 22 Jun 2018. doi:10.2519/jospt.2018.8169.

Diagnoses and time to recovery among injured recreational runners in the RUN CLEVER trial

PURPOSE

The purpose of the present study was to describe the incidence proportion of different types of running-related injuries (RRI) among recreational runners and to determine their time to recovery.

METHODS

A sub-analysis of the injured runners included in the 839-person, 24-week randomized trial named Run Clever. During follow-up, the participants reported levels of pain in different anatomical areas on a weekly basis. In case injured, runners attended a clinical examination at a physiotherapist, who provided a diagnosis, e.g., medial tibial stress syndrome (MTSS), Achilles tendinopathy (AT), patellofemoral pain (PFP), iliotibial band syndrome (ITBS) and plantar fasciopathy (PF). The diagnose-specific injury proportions (IP) and 95% confidence intervals (CI) were calculated using descriptive statistics. The time to recovery was defined as the time from the first registration of pain until total pain relief in the same anatomical area. It was reported as medians and interquartile range (IQR) if possible.

RESULTS

A total of 140 runners were injured at least once leading to a 24-week cumulative injury proportion of 32% [95% CI: 26%; 37%]. The diagnoses with the highest incidence proportion were MTSS (IP = 16% [95% CI: 9.3%; 22.9%], AT (IP = 8.9% [95% CI: 3.6%; 14.2%], PFP (IP = 8% [95% CI: 3.0%; 13.1%]. The median time to recovery for all types of injuries was 56 days (IQR = 70 days). Diagnose-specific time-to-recoveries included 70 days (IQR = 89 days) for MTSS, 56 days (IQR = 165 days) for AT, 49 days (IQR = 63 days) for PFP.

CONCLUSION

The most common running injuries among recreational runners were MTSS followed by AT, PFP, ITBS and PF. In total, 77 injured participants recovered their RRI and the median time to recovery for all types of injuries was 56 days and MTSS was the diagnosis with the longest median time to recovery, 70 days.

Progression in Running Intensity or Running Volume and the Development of Specific Injuries in Recreational Runners: Run Clever, a Randomized Trial Using Competing Risks

BACKGROUND

It has been proposed that training intensity and training volume are associated with specific running-related injuries. If such an association exists, secondary preventive measures could be initiated by clinicians, based on symptoms of a specific injury diagnosis.

OBJECTIVES

To test the following hypotheses: (1) a running schedule focusing on running intensity (S-I) would increase the risk of sustaining Achilles tendinopathy, gastrocnemius injuries, and plantar fasciitis compared with hypothesized volume-related injuries; and (2) a running schedule focusing on running volume (S-V) would increase the risk of sustaining patellofemoral pain syndrome, iliotibial band syndrome, and patellar tendinopathy compared with hypothesized intensity-related injuries.

METHODS

In this randomized clinical trial and etiology study, healthy recreational runners were included in a 24-week follow-up, divided into 8-week preconditioning and 16-week specific-focus training periods. Participants were randomized to 1 of 2 running schedules: S-I or S-V. The S-I group progressed the amount of high-intensity running (88% maximal oxygen consumption [VO₂max] or greater) each week, and the S-V group progressed total weekly running volume. A global positioning system watch or smartphone collected data on running. Running-related injuries were diagnosed based on a clinical examination. Estimates were reported as risk difference and 95% confidence interval (CI).

RESULTS

Of 447 runners, a total of 80 sustained an injury (S-I, n = 36; S-V, n = 44). Risk differences (95% CIs) of intensity injuries in the S-I group were -0.8% (-5.0%, 3.4%) at 2 weeks, -0.8% (-6.7%, 5.1%) at 4 weeks, -2.0% (-9.2%, 5.2%) at 8 weeks, and -5.1% (-16.5%, 6.3%) at 16 weeks. Risk differences (95% CIs) of volume injuries in the S-V group were -0.9% (-5.0%, 3.2%) at 2 weeks, -2.0% (-7.5%, 3.5%) at 4 weeks, -3.2% (-9.1%, 2.7%) at 8 weeks, and -3.4% (13.2%, 6.2%) at 16 weeks.

CONCLUSION

No difference in risk of hypothesized intensity- and volume-specific running-related injuries exists between the 2 running schedules focused on progression in either running intensity or volume.

LEVEL OF EVIDENCE

Etiology, level 1b. J Orthop Sports Phys Ther 2018;48(10):740-748. Epub 12 Jun 2018. doi:10.2519/jospt.2018.8062.

Study protocol of a 52-week Prospective Running INjury study in Gothenburg (SPRING)

INTRODUCTION

It is assumed that a running-related (overuse) injury occurs when a specific structure of the human body is exposed to a load that exceeds that structures' load capacity. Therefore, monitoring training load is an important key to understanding the development of a running-related injury. Additionally, other distribution, magnitude and capacity-related factors should be considered when aiming to understand the causal chain of injury development. This paper presents a study protocol for a prospective cohort study that aims to add comprehensive information on the aetiology of running-related injuries and present a new approach for investigating changes in training load with regard to running-related injuries.

METHODS AND ANALYSIS

This study focused on recreational runners, that is, runners exposed to a minimum weekly average of 15 km for at least 1 year. Participants will undergo baseline tests consisting of a clinical/anthropometrical examination and biomechanical measurements. Furthermore, participants will log all training sessions in a diary on a weekly basis for 1 year. The primary exposure variable is changes in training load. A medical practitioner will examine runners suffering from running-related pain and, if possible, make a clear diagnosis. Finally, additional time-varying exposure variables will be included in the main analysis, whereas the analysis for the secondary purpose is based on time-fixed baseline-related risk factors.

ETHICS AND DISSEMINATION

Ethical approval (DNR: 712-15) for the study and its design was obtained from the Gothenburg regional ethical review board. The results of the study will be published in peer-reviewed journals.

Health and Economic Burden of Running-Related Injuries in Dutch Trailrunners: A Prospective Cohort Study

Background

Trailrunning is becoming very popular. However, the risk and burden of running-related injuries (RRI) in trailrunning is not well established.

Objective

To investigate the prevalence, injury rate, severity, nature, and economic burden of RRIs in Dutch trailrunners.

Methods

This prospective cohort study included 228 trailrunners aged 18 years or over (range 23–67), and was conducted between October 2013 and December 2014. After completing the baseline questionnaire, the Oslo Sports Trauma Research Center Questionnaire on Health Problems was administered every 2 weeks to collect data on RRIs. Participants who reported RRIs were asked about healthcare utilization (direct costs) and absenteeism from paid work (indirect costs). RRI was defined as disorders of the musculoskeletal system or concussions experienced or sustained during participation in running.

Results

The mean prevalence of RRIs measured over time was 22.4 % [95 % confidence interval (CI) 20.9–24.0], and the injury rate was 10.7 RRIs per 1000 h of running (95 % CI 9.4–12.1). The prevalence was higher for overuse (17.7 %; 95 % CI 15.9–19.5) than for acute (4.1 %; 95 % CI 3.3–5.0) RRIs. Also, the injury rate was higher for overuse (8.1; 95 % CI 6.9–9.3) than for acute (2.7; 95 % CI 2.0–3.4) RRIs. The median of the severity score was 35.0 [25–75 %, interquartile range (IQR) 22.0–55.7], and the median of the duration of RRIs was 2.0 weeks (IQR 2.0–6.0) during the study. The total economic burden of RRIs was estimated at €172.22 (95 % CI 117.10–271.74) per RRI, and €1849.49 (95 % CI 1180.62–3058.91) per 1000 h of running. An RRI was estimated to have a direct cost of €60.92 (95 % CI 45.11–94.90) and an indirect cost of €111.30 (95 % CI 61.02–192.75).

Conclusions

The health and economic burden of RRIs presented in this study are significant for trailrunners and for society. Therefore, efforts should be made in order to prevent RRIs in trailrunners.

Electronic supplementary material

The online version of this article (doi:10.1007/s40279-016-0551-8) contains supplementary material, which is available to authorized users.

How (not) to interpret a non-causal association in sports injury science

OBJECTIVE

To discuss the interpretability of non-causal associations to sports injury development exemplified via the relationship between navicular drop (ND) and running-related injury (RRI) in novice runners using neutral shoes.

DESIGN

1-year prospective cohort study.

SETTING

Denmark.

PARTICIPANTS

926 novice runners, representing 1852 feet, were included.

MAIN OUTCOME MEASURE

The outcome was "a musculoskeletal complaint of the lower extremity or back caused by running, which restricted the amount of running for at least a week".

RESULTS

Fewer feet with small ND than those feet with a reference ND sustained injuries at 50 (risk difference (RD) = -4.1% [95%CI = -7.9%;-0.4%]) and 100 km (RD = -5.3% [95%CI = -9.9%;-0.7%]). Similarly, fewer feet with a large ND sustained injuries than the feet with a reference drop at 250 (RD = -7.6% [95%CI = -14.9%;-0.3%]) and 500 km (RD = -9.8% [95%CI = -19.1%;-0.4%]).

CONCLUSION

Non-causal associations can help to identify sub-groups of athletes at an increased or decreased risk of sports injury. Based on the current results, those with a small or large navicular drop sustain fewer injuries than those with a reference drop. Importantly, navicular drop does not cause RRIs, but influences the relationship between training load and RRI. This illustrates that non-causal associations are unsuitable to respond to the question: Why do sports injury develop?

Achilles Pain, Stiffness, and Muscle Power Deficits: Midportion Achilles Tendinopathy Revision 2018

The Orthopaedic Section of the American Physical Therapy Association (APTA) has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). The purpose of these revised clinical practice guidelines is to review recent peer-reviewed literature and make recommendations related to midportion Achilles tendinopathy. J Orthop Sports Phys Ther 2018;48(5):A1-A38. doi:10.2519/jospt.2018.0302.

Injury prevalence across sports: a descriptive analysis on a representative sample of the Danish population

Background

Physical activity plays an important role in public health, owing to a range of health-related benefits that it provides. Sports-related injuries are known to be an important barrier to continued physical activity. Still, the prevalence of injuries on a general population level has not yet been explored in a descriptive epidemiological investigation. The purpose of the questionnaire-based study, therefore, was to describe the prevalence of injury in a representative sample of the Danish population.

Methods

Two samples of 10,000 adults (> 15 years) and 6500 children and adolescents (7–15 years) were invited to respond to a web-based questionnaire. Of these, 3498 adults (35.0%) and 3221 children (49.6%) responded successfully. The definition of sports injury was time-loss and medical attention-based, inhibiting participants from sports activity for at least 7 days, and/or involved contact with a healthcare professional, respectively.

Results

Amongst adults, 642 (18.4% [95%CI: 17.1%; 19.6%]) reported to have had an injury within the past 12 months. Males reported significantly more injuries than females (difference in prevalence proportion: 9.2%-points [95%CI: 6.7%-points; 11.8%-points]). The prevalence of injuries was greatest in running (n_inj = 198), football (n_inj = 94) and strength training (n_inj = 89).

Amongst children, 621 (19.3% [95%CI: 17.9%; 20.6%]) had been injured. No difference in injury prevalence proportion existed between boys and girls. The prevalence of injuries was greatest in football (n_inj = 235), handball (n_inj = 86) and gymnastics (n_inj = 66).

Conclusions

Sports injuries seem to be very frequent in Denmark, since a total of 18.4% of the adults and 19.3% of the children reported having had one or more injuries within the past 12 months, equal to either time lost with physical activity and/or contact to the health care system.

Design of ProjectRun21: a 14-week prospective cohort study of the influence of running experience and running pace on running-related injury in half-marathoners

BACKGROUND

Participation in half-marathon has been steeply increasing during the past decade. In line, a vast number of half-marathon running schedules has surfaced. Unfortunately, the injury incidence proportion for half-marathoners has been found to exceed 30% during 1-year follow-up. The majority of running-related injuries are suggested to develop as overuse injuries, which leads to injury if the cumulative training load over one or more training sessions exceeds the runners' load capacity for adaptive tissue repair. Owing to an increase of load capacity along with adaptive running training, the runners' running experience and pace abilities can be used as estimates for load capacity. Since no evidence-based knowledge exist of how to plan appropriate half-marathon running schedules considering the level of running experience and running pace, the aim of ProjectRun21 is to investigate the association between running experience or running pace and the risk of running-related injury.

METHODS

Healthy runners using Global Positioning System (GPS) watch between 18 and 65 years will be invited to participate in this 14-week prospective cohort study. Runners will be allowed to self-select one of three half-marathon running schedules developed for the study. Running data will be collected objectively by GPS. Injury will be based on the consensus-based time loss definition by Yamato et al.: "Running-related (training or competition) musculoskeletal pain in the lower limbs that causes a restriction on or stoppage of running (distance, speed, duration, or training) for at least 7 days or 3 consecutive scheduled training sessions, or that requires the runner to consult a physician or other health professional". Running experience and running pace will be included as primary exposures, while the exposure to running is pre-fixed in the running schedules and thereby conditioned by design. Time-to-event models will be used for analytical purposes.

DISCUSSION

ProjectRun21 will examine if particular subgroups of runners with certain running experiences and running paces seem to sustain more running-related injuries compared with other subgroups of runners. This will enable sport coaches, physiotherapists as well as the runners to evaluate their injury risk of taking up a 14-week running schedule for half-marathon.

RUNNING INJURY DEVELOPMENT: THE ATTITUDES OF MIDDLE- AND LONG-DISTANCE RUNNERS AND THEIR COACHES

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.

DO GENERAL MEDICAL PRACTITIONERS EXAMINE INJURED RUNNERS?

BACKGROUND

General Medical Practitioners (GMP) in Denmark perform clinical examinations of patients with musculoskeletal pain. However, the prevalence proportion of examinations caused by running-related injuries remains unknown.

PURPOSE

The primary purpose of the present study was to estimate the prevalence proportion of consultations in general medical practice caused by running-related injuries. The secondary purpose was to estimate the prevalence proportion of injured runners, who consult their GMP, that are referred to additional examinations or treatments.

STUDY DESIGN

A survey-based study.

METHODS

An online survey was distributed in October and November 2015 to more than 370 GMPs in Denmark and completed by 27.

RESULTS

The median prevalence proportion of consultations caused by running-related injuries in the prior two weeks was 0.80% [25th percentile = 0.00%; 75th percentile = 1.43%]. Ten (37%) GMPs reported to refer between 0-24% of the injured runners to additional examination or treatment, whereas thirteen (48%) of GMPs referred between 25-49% and four (15%) referred 50-74% of injured runners.

CONCLUSION

Although a very small part (<1%) of the GMPs consultations were related to running injuries, this result suggests that injured runners seek advice in the primary health-care system in Denmark. As a consequence, physiotherapists willing to treat runners with running-related injuries may inform the GMPs in their local community about the treatment possibilities they offer. The low response-proportion highlights the challenges recruiting GMPs willing to respond to questionnaires on running-related injuries. It is plausible to assume that the estimates reported in the present study are overestimated owing to selection bias.

LEVEL OF EVIDENCE

3.

Plantar fasciitis in athletes: diagnostic and treatment strategies. A systematic review

BACKGROUND

Plantar fasciitis (PF) is reported in different sports mainly in running and soccer athletes. Purpose of this study is to conduct a systematic review of published literature concerning the diagnosis and treatment of PF in both recreational and élite athletes. The review was conducted and reported in accordance with the PRISMA statement.

METHODS

The following electronic databases were searched: PubMed, Cochrane Library and Scopus. As far as PF diagnosis, we investigated the electronic databases from January 2006 to June 2016, whereas in considering treatments all data in literature were investigated.

RESULTS

For both diagnosis and treatment, 17 studies matched inclusion criteria. The results have highlighted that the most frequently used diagnostic techniques were Ultrasonography and Magnetic Resonance Imaging. Conventional, complementary, and alternative treatment approaches were assessed.

CONCLUSIONS

In reviewing literature, we were unable to find any specific diagnostic algorithm for PF in athletes, due to the fact that no different diagnostic strategies were used for athletes and non-athletes. As for treatment, a few literature data are available and it makes difficult to suggest practice guidelines. Specific studies are necessary to define the best treatment algorithm for both recreational and élite athletes.

LEVEL OF EVIDENCE

Ib.

A framework for the etiology of running-related injuries

The etiology of running-related injury is important to consider as the effectiveness of a given running-related injury prevention intervention is dependent on whether etiologic factors are readily modifiable and consistent with a biologically plausible causal mechanism. Therefore, the purpose of the present article was to present an evidence-informed conceptual framework outlining the multifactorial nature of running-related injury etiology. In the framework, four mutually exclusive parts are presented: (a) Structure-specific capacity when entering a running session; (b) structure-specific cumulative load per running session; (c) reduction in the structure-specific capacity during a running session; and (d) exceeding the structure-specific capacity. The framework can then be used to inform the design of future running-related injury prevention studies, including the formation of research questions and hypotheses, as well as the monitoring of participation-related and non-participation-related exposures. In addition, future research applications should focus on addressing how changes in one or more exposures influence the risk of running-related injury. This necessitates the investigation of how different factors affect the structure-specific load and/or the load capacity, and the dose-response relationship between running participation and injury risk. Ultimately, this direction allows researchers to move beyond traditional risk factor identification to produce research findings that are not only reliably reported in terms of the observed cause-effect association, but also translatable in practice.

Influence of custom-made and prefabricated insoles before and after an intense run

Each time the foot contacts the ground during running there is a rapid deceleration that results in a shock wave that is transmitted from the foot to the head. The fatigue of the musculoskeletal system during running may decrease the ability of the body to absorb those shock waves and increase the risk of injury. Insoles are commonly prescribed to prevent injuries, and both custom-made and prefabricated insoles have been observed to reduce shock accelerations during running. However, no study to date has included a direct comparison of their behaviour measured over the same group of athletes, and therefore great controversy still exists regarding their effectiveness in reducing impact loading during running. The aim of the study was to analyse the acute differences in stride and shock parameters while running on a treadmill with custom-made and prefabricated insoles. Stride parameters (stride length, stride rate) and shock acceleration parameters (head and tibial peak acceleration, shock magnitude, acceleration rate, and shock attenuation) were measured using two triaxial accelerometers in 38 runners at 3.33 m/s before and after a 15-min intense run while using the sock liner of the shoe (control condition), prefabricated insoles and custom-made insoles. No differences in shock accelerations were found between the custom-made and the control insoles. The prefabricated insoles increased the head acceleration rate (post-fatigue, p = 0.029) compared to the control condition. The custom-made reduced tibial (pre-fatigue, p = 0.041) and head acceleration rates (pre-fatigue and post-fatigue, p = 0.01 and p = 0.046) compared to the prefabricated insoles. Neither the stride nor the acceleration parameters were modified as a result of the intense run. In the present study, the acute use of insoles (custom-made, prefabricated) did not reduce shock accelerations compared to the control insoles. Therefore, their effectiveness at protecting against injuries associated with elevated accelerations is not supported and remains unclear.

Validity of Self-Reported Running Distance

It is unclear whether there is a difference between subjective evaluation and objective global positioning systems (GPS) measurement of running distance. The purpose of this study was to investigate if such difference exists. A total of 100 participants (51% men; median age, 41.5; body mass, 78.1 kg ±13.8 SD) completed a run of free choice, then subjectively reported the distance in kilometer (km). This information was subsequently compared with the distance derived from a nondifferential GPS watch using paired t-tests and Bland-Altman's 95% limits of agreement. No significant difference was found between the mean paired differences between subjective evaluations and GPS measurements (1.86%, 95% confidence interval = -1.53%; 5.25%, p = 0.96). The Bland-Altman 95% limits of agreement revealed considerable variation (lower limit = -28% and upper limit = 40%). Such variation exceeds the clinical error range of 10%. In conclusion, the mean running distance (km) is similar between self-reporting and GPS measurements. However, researchers should consider using GPS measurements in favor of subjective reporting of running distance because of considerable variation on an individual level.

The design of the run Clever randomized trial: running volume, -intensity and running-related injuries

Background

Injury incidence and prevalence in running populations have been investigated and documented in several studies. However, knowledge about injury etiology and prevention is needed. Training errors in running are modifiable risk factors and people engaged in recreational running need evidence-based running schedules to minimize the risk of injury. The existing literature on running volume and running intensity and the development of injuries show conflicting results. This may be related to previously applied study designs, methods used to quantify the performed running and the statistical analysis of the collected data. The aim of the Run Clever trial is to investigate if a focus on running intensity compared with a focus on running volume in a running schedule influences the overall injury risk differently.

Methods/design

The Run Clever trial is a randomized trial with a 24-week follow-up. Healthy recreational runners between 18 and 65 years and with an average of 1–3 running sessions per week the past 6 months are included. Participants are randomized into two intervention groups: Running schedule-I and Schedule-V. Schedule-I emphasizes a progression in running intensity by increasing the weekly volume of running at a hard pace, while Schedule-V emphasizes a progression in running volume, by increasing the weekly overall volume. Data on the running performed is collected by GPS. Participants who sustain running-related injuries are diagnosed by a diagnostic team of physiotherapists using standardized diagnostic criteria. The members of the diagnostic team are blinded. The study design, procedures and informed consent were approved by the Ethics Committee Northern Denmark Region (N-20140069).

Discussion

The Run Clever trial will provide insight into possible differences in injury risk between running schedules emphasizing either running intensity or running volume. The risk of sustaining volume- and intensity-related injuries will be compared in the two intervention groups using a competing risks approach. The trial will hopefully result in a better understanding of the relationship between the running performed and possible differences in running-related injury risk and the injuries developed.

Trial registration

Clinical Trials NCT02349373 – January 23, 2015.

What are the Differences in Injury Proportions Between Different Populations of Runners? A Systematic Review and Meta-Analysis

BACKGROUND

Many runners suffer from injuries. No information on high-risk populations is available so far though.

OBJECTIVES

The aims of this study were to systematically review injury proportions in different populations of runners and to compare injury locations between these populations.

DATA SOURCES

An electronic search with no date restrictions was conducted up to February 2014 in the PubMed, Embase, SPORTDiscus and Web of Science databases. The search was limited to original articles written in English. The reference lists of the included articles were checked for potentially relevant studies.

STUDY ELIGIBILITY CRITERIA

Studies were eligible when the proportion of running injuries was reported and the participants belonged to one or more homogeneous populations of runners that were clearly described. Study selection was conducted by two independent reviewers, and disagreements were resolved in a consensus meeting.

STUDY APPRAISAL AND SYNTHESIS METHODS

Details of the study design, population of runners, sample size, injury definition, method of injury assessment, number of injuries and injury locations were extracted from the articles. The risk of bias was assessed with a scale consisting of eight items, which was specifically developed for studies focusing on musculoskeletal complaints.

RESULTS

A total of 86 articles were included in this review. Where possible, injury proportions were pooled for each identified population of runners, using a random-effects model. Injury proportions were affected by injury definitions and durations of follow-up. Large differences between populations existed. The number of medical-attention injuries during an event was small for most populations of runners, except for ultra-marathon runners, in which the pooled estimate was 65.6%. Time-loss injury proportions between different populations of runners ranged from 3.2% in cross-country runners to 84.9% in novice runners. Overall, the proportions were highest among short-distance track runners and ultra-marathon runners.

LIMITATIONS

The results were pooled by stratification of studies according to the population, injury definition and follow-up/recall period; however, heterogeneity was high.

CONCLUSIONS

Large differences in injury proportions between different populations of runners existed. Injury proportions were affected by the duration of follow-up. A U-shaped pattern between the running distance and the time-loss injury proportion seemed to exist. Future prospective studies of injury surveillance are highly recommended to take running exposure and censoring into account.

High eccentric hip abduction strength reduces the risk of developing patellofemoral pain among novice runners initiating a self-structured running program: a 1-year observational study

STUDY DESIGN

Observational prospective cohort study with 1-year follow-up.

OBJECTIVES

To investigate the relationship between eccentric hip abduction strength and the development of patellofemoral pain (PFP) in novice runners during a self-structured running regime.

BACKGROUND

Recent research indicates that gluteal muscle weakness exists in individuals with PFP. However, current prospective research has been limited to the evaluation of isometric strength, producing inconsistent findings. Considering that hip muscles, including the gluteus maximus and medius, activate eccentrically to control hip and pelvic motion during weight-bearing activities such as running, the potential link between eccentric strength and PFP risk should be evaluated.

METHODS

Eight hundred thirty-two novice runners were included at baseline, and 629 participants were included in the final analysis. Maximal eccentric hip abduction strength was measured using a handheld dynamometer prior to initiating a self-structured running program. The diagnostic criteria to classify knee pain as PFP were based on a thorough clinical examination. Participants were followed for 12 months and training characteristics were gathered with a global positioning system.

RESULTS

Results from the unadjusted generalized linear regression model for cumulative risk at 25 and 50 km indicated differences in cumulative risk of PFP between high strength, normal strength, and low strength (P<.05), with higher strength associated with reduced risk.

CONCLUSION

Findings from this study indicate that, among novice runners, a level of peak eccentric hip abduction strength that is higher than normal may reduce the risk of PFP during the first 50 km of a self-structured running program.