Running shoe cushioning properties at the rearfoot and forefoot and their relationship to injury: study protocol for a randomised controlled trial on leisure-time runners

Previous work has demonstrated the protective effect of shoe cushioning on injury risk in leisure-time runners, but most models currently available on the market have greater cushioning than those investigated so far. Also, the optimal level of cushioning and the role of cushioning on the forepart of the shoe for injury prevention are still unknown. The main aim of this study is to determine whether (1) current 'extra soft' cushioning material at the rear part of the shoe reduces injury risk compared with stiffer material and (2) cushioning under the forepart of the shoe also contributes to injury risk reduction. This randomised trial with a 6-month intervention will involve 1000+ healthy leisure-time runners who will randomly receive one of the three running shoe versions. Study shoe versions will differ in their cushioning properties (ie, stiffness) at the rear or the forepart. Participants will self-report any lower limb or lower back problems on a dedicated electronic system every week, while the system will collect training data from the participant's sports watch. Time-to-event analyses will be used to compare injury risk between the three study groups and to investigate the association between the runner's characteristics, cushioning level and position, training and injury risk. The study was approved by the National Ethics Committee for Research (Ref: 202405/02 v2.0), and the protocol has been registered on https://clinicaltrials.gov/ (NCT06384872, 02/08/2024). Outcomes will be disseminated through presentations at international conferences and publications in peer-reviewed journals, popular magazines and specialised websites.

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

Objective

To investigate asymmetry in spatiotemporal and kinetic variables in 800+ recreational runners, identify determinants of asymmetry, investigate if asymmetry is related to greater running injury risk and compare spatiotemporal and kinetic variables between the involved and uninvolved limb at baseline in runners having sustained an injury during follow-up.

Methods

836 healthy recreational runners (38.6% women) were tested on an instrumented treadmill at their preferred running speed at baseline and followed up for 6 months. From ground reaction force recordings, spatiotemporal and kinetic variables were derived for each lower limb. The Symmetry Index was computed for each variable. Correlations and multiple regression analyses were performed to identify potential determinants of asymmetry. Cox regression analyses investigated the association between asymmetry and injury risk. Analysis of variance for repeated measures was used to compare the involved and uninvolved limbs in runners who had sustained injuries during follow-up.

Results

107 participants reported at least one running-related injury. Leg length discrepancy and fat mass were the most common determinants of asymmetry, but all correlation coefficients were negligible (0.01-0.13) and explained variance was very low (multivariable-adjusted R2<0.01-0.03). Greater asymmetry for flight time and peak breaking force was associated with lower injury risk (HR (95% CI): 0.80 (0.64 to 0.99) and 0.96 (0.93 to 0.98), respectively). No between-limb differences were observed in runners having sustained an injury.

Conclusion

Gait asymmetry was not associated with higher injury risk for investigated spatiotemporal and kinetic variables.

Trial registration number

NCT03115437.

Reference Values and Determinants of Spatiotemporal and Kinetic Variables in Recreational Runners

Background

Identifying atypical lower limb biomechanics may help prevent the occurrence or recurrence of running-related injuries. No reference values for spatiotemporal or kinetic variables in healthy recreational runners are available in the scientific literature to support clinical management.

Purpose

To (1) present speed- and sex-stratified reference values for spatiotemporal and kinetic variables in healthy adult recreational runners; (2) identify the determinants of these biomechanical variables; and (3) develop reference regression equations that can be used as a guide in a clinical context.

Study Design

Descriptive laboratory study.

Methods

This study involved 860 healthy recreational runners (age, 19-65 years [38.5% women]) tested on an instrumented treadmill at their preferred running speed in randomly allocated, standardized running shoes with either hard or soft cushioning. Twelve common spatiotemporal and kinetic variables-including contact time, flight time, duty factor, vertical oscillation, step cadence, step length, vertical impact peak (VIP), time to VIP, vertical average loading rate, vertical stiffness, peak vertical ground-reaction force (GRF), and peak braking force-were derived from GRF recordings. Reference values for each biomechanical variable were calculated using descriptive statistics and stratified by sex and running speed category (≤7, 8, 9, 10, 11, 12, 13, 14, and ≥15 km/h). Correlations and multiple regression analyses were performed to identify potential determinants independently associated with each biomechanical variable and generate reference equations.

Results

The mean running speed was 10.5 ± 1.3 km/h and 9 ± 1.1 km/h in men and women, respectively. While all potential predictors were significantly correlated with many of the 12 biomechanical variables, only running speed showed high correlations (r > 0.7). The adjusted R2 of the multiple regression equations ranged from 0.19 to 0.88.

Conclusion

This study provides reference values and equations that may guide clinicians and researchers in interpreting spatiotemporal and kinetic variables in recreational runners.

Clinical Relevance

The reference values can be used as targets for clinicians working with recreational runners in cases where there is a clinical suspicion of a causal relationship between atypical biomechanics and running-related injury.

Lower impact forces but greater burden for the musculoskeletal system in running shoes with greater cushioning stiffness

In a recent randomised trial investigating running shoe cushioning, injury risk was greater in recreational runners who trained in the shoe version with greater cushioning stiffness (Stiff) compared to those using the Soft version. However, vertical impact peak force (VIPF) was lower in the Stiff version. To investigate further the mechanisms involved in the protective effect of greater cushioning, the present study used an intra-subject design and analysed the differences in running kinematics and kinetics between the Stiff and Soft shoe versions on a subsample of 41 runners from the previous trial. Data were recorded in the two shoe conditions using an instrumented treadmill at 10 km.h^-1. VIPF was confirmed to be lower in the Stiff version compared to the Soft version (1.39 ± 0.25 vs. 1.50 ± 0.25 BW, respectively; p = 0.009, d = 0.42), but not difference was observed in vertical loading rate (p = 0.255 and 0.897 for vertical average and instantaneous loading rate, respectively). Ankle eversion maximal velocity was not different (p = 0.099), but the Stiff version induced greater ankle negative work (-0.55 ± 0.09 vs. -0.52 ± 0.10 J.kg^-1; p = 0.009, d = 0.32), maximal ankle negative power (-7.21 ± 1.90 vs. -6.96 ± 1.92 W.kg^-1; p = 0.037, d = 0.13) and maximal hip extension moment (1.25 ± 0.32 vs.1.18 ± 0.30 N.m.kg^-1; p = 0.009, d = 0.22). Our results suggest that the Stiff shoe version is related to increased mechanical burden for the musculoskeletal system, especially around the ankle joint.Trial registration: ClinicalTrials.gov identifier: NCT03115437.

P07-07 Put the promotion of physical activity for people with non-communicable diseases on the political agenda in Luxembourg!

Issue/problem

In 1984, cardiologists and cardiac patients created an association offering physical activity (PA) for people with cardiovascular diseases in Luxembourg (0.6 million inhabitants). During the last 20 years, several associations created therapeutic PA for people with a wide range of non-communicable diseases (NCDs). Today more than 70 hours of therapeutic PA are weekly offered. Nevertheless, the organization of these PA is incomplete and not enough patients benefit from it.

Description of the problem

Sustainability of privately organized courses is challenging. Despite a governmental financial support, the organization of PA offer remains mainly based on the idealism of a limited number of volunteers. However, this kind of commitment is disappearing and jeopardizes a correct offer of therapeutic PA. Only a minority of physicians are referring their patients on a regular basis and only a minority of them are engaging in an active lifestyle.

Results

A project was launched in 2013 to compile, monitor and promote the therapeutic PA offered by different associations. As a result of this project, six associations created a sport federation in 2016 destined to improve the organization of therapeutic PA for people with NCDs. In 2018, the federation obtained an increase in the financial support from the Ministry of Health. The same year, a campaign promoted the therapeutic PA but had no impact on the number of patients counselled about therapeutic PA (26.6%) and on the physician's knowledge of the therapeutical PA offer (21%). The federation is now trying to develop and implement deeper actions, such as a PA referral scheme.

Lessons

The collaborative and synergetic work of the different associations offering PA for people with NCDs bundled their activities resulting in an increased consideration and support from the Ministry of Health. Nevertheless, structural improvements should be conducted to increase sustainably the number of physically active patients.

Main messages

Spatiotemporal and Ground-Reaction Force Characteristics as Risk Factors for Running-Related Injury: A Secondary Analysis of a Randomized Trial Including 800+ Recreational Runners

BACKGROUND

Running biomechanics may play a role in running-related injury development, but to date, only a few modifiable factors have been prospectively associated with injury risk.

PURPOSE

To identify risk factors among spatiotemporal and ground-reaction force characteristics in recreational runners and to investigate whether shoe cushioning modifies the association between running biomechanics and injury risk.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Recreational runners (N = 848) were tested on an instrumented treadmill at their preferred running speed in randomly allocated, standardized running shoes (with either hard or soft cushioning). Typical kinetic and spatiotemporal metrics were derived from ground-reaction force recordings. Participants were subsequently followed up for 6 months regarding running activity and injury. Cox regression models for competing risk were used to investigate the association between biomechanical risk factors and injury risk, including stratified analyses by shoe version.

RESULTS

In the crude analysis, greater injury risk was found for greater step length (subhazard rate ratio [SHR], 1.01; 95% CI, 1.00-1.02; P = .038), longer flight time (SHR, 1.00; 95% CI, 1.00-1.01; P = .028), shorter contact time (SHR, 0.99; 95% CI, 0.99-1.00; P = .030), and lower duty factor (defined as the ratio between contact time and stride time; SHR, 0.95; 95% CI, 0.91-0.98; P = .005). In the stratified analyses by shoe version, adjusted for previous injury and running speed, lower duty factor was associated with greater injury risk in those using the soft shoes (SHR, 0.92; 95% CI, 0.85-0.99; P = .042) but not in those using the hard shoes (SHR, 0.97; 95% CI, 0.91-1.04; P = .348).

CONCLUSION

Lower duty factor is an injury risk factor, especially for softer shoe use. Contrary to widespread beliefs, vertical impact peak, loading rate, and step rate were not injury risk factors in recreational runners.

REGISTRATION

NCT03115437 (ClinicalTrials.gov identifier).

Relevance of Frequency-Domain Analyses to Relate Shoe Cushioning, Ground Impact Forces and Running Injury Risk: A Secondary Analysis of a Randomized Trial With 800+ Recreational Runners

Cushioning systems in running shoes are used assuming that ground impact forces relate to injury risk and that cushioning materials reduce these impact forces. In our recent trial, the more cushioned shoe version was associated with lower injury risk. However, vertical impact peak force was higher in participants with the Soft shoe version. The primary objective of this study was to investigate the effect of shoe cushioning on the time, magnitude and frequency characteristics of peak forces using frequency-domain analysis by comparing the two study groups from our recent trial (Hard and Soft shoe group, respectively). The secondary objective was to investigate if force characteristics are prospectively associated with the risk of running-related injury. This is a secondary analysis of a double-blinded randomized trial on shoe cushioning with a biomechanical running analysis at baseline and a 6-month follow-up on running exposure and injury. Participants (n = 848) were tested on an instrumented treadmill at their preferred running speed in their randomly allocated shoe condition. The vertical ground reaction force signal for each stance phase was decomposed into the frequency domain using the discrete Fourier transform. Both components were recomposed into the time domain using the inverse Fourier transform. An analysis of variance was used to compare force characteristics between the two study groups. Cox regression analysis was used to investigate the association between force characteristics and injury risk. Participants using the Soft shoes displayed lower impact peak force (p < 0.001, d = 0.23), longer time to peak force (p < 0.001, d = 0.25), and lower average loading rate (p < 0.001, d = 0.18) of the high frequency signal compared to those using the Hard shoes. Participants with low average and instantaneous loading rate of the high frequency signal had lower injury risk [Sub hazard rate ratio (SHR) = 0.49 and 0.55; 95% Confidence Interval (CI) = 0.25–0.97 and 0.30–0.99, respectively], and those with early occurrence of impact peak force (high frequency signal) had greater injury risk (SHR = 1.60; 95% CI = 1.05–2.53). Our findings may explain the protective effect of the Soft shoe version previously observed. The present study also demonstrates that frequency-domain analyses may provide clinically relevant impact force characteristics.

Clinical Trial Registration:https://clinicaltrials.gov/, identifier: 9NCT03115437.

Smartphone-Based Interventions for Physical Activity Promotion: Scoping Review of the Evidence Over the Last 10 Years

Background

Several reviews of mobile health (mHealth) physical activity (PA) interventions suggest their beneficial effects on behavior change in adolescents and adults. Owing to the ubiquitous presence of smartphones, their use in mHealth PA interventions seems obvious; nevertheless, there are gaps in the literature on the evaluation reporting processes and best practices of such interventions.

Objective

The primary objective of this review is to analyze the development and evaluation trajectory of smartphone-based mHealth PA interventions and to review systematic theory- and evidence-based practices and methods that are implemented along this trajectory. The secondary objective is to identify the range of evidence (both quantitative and qualitative) available on smartphone-based mHealth PA interventions to provide a comprehensive tabular and narrative review of the available literature in terms of its nature, features, and volume.

Methods

We conducted a scoping review of qualitative and quantitative studies examining smartphone-based PA interventions published between 2008 and 2018. In line with scoping review guidelines, studies were not rejected based on their research design or quality. This review, therefore, includes experimental and descriptive studies, as well as reviews addressing smartphone-based mHealth interventions aimed at promoting PA in all age groups (with a subanalysis conducted for adolescents). Two groups of studies were additionally included: reviews or content analyses of PA trackers and meta-analyses exploring behavior change techniques and their efficacy.

Results

Included articles (N=148) were categorized into 10 groups: commercial smartphone app content analyses, smartphone-based intervention review studies, activity tracker content analyses, activity tracker review studies, meta-analyses of PA intervention studies, smartphone-based intervention studies, qualitative formative studies, app development descriptive studies, qualitative follow-up studies, and other related articles. Only 24 articles targeted children or adolescents (age range: 5-19 years). There is no agreed evaluation framework or taxonomy to code or report smartphone-based PA interventions. Researchers did not state the coding method, used various evaluation frameworks, or used different versions of behavior change technique taxonomies. In addition, there is no consensus on the best behavior change theory or model that should be used in smartphone-based interventions for PA promotion. Commonly reported systematic practices and methods have been successfully identified. They include PA recommendations, trial designs (randomized controlled trials, experimental trials, and rapid design trials), mixed methods data collection (surveys, questionnaires, interviews, and focus group discussions), scales to assess app quality, and industry-recognized reporting guidelines.

Conclusions

Smartphone-based mHealth interventions aimed at promoting PA showed promising results for behavior change. Although there is a plethora of published studies on the adult target group, the number of studies and consequently the evidence base for adolescents is limited. Overall, the efficacy of smartphone-based mHealth PA interventions can be considerably improved through a more systematic approach of developing, reporting, and coding of the interventions.

Can the "Appropriate" Footwear Prevent Injury in Leisure-Time Running? Evidence Versus Beliefs

Leisure-time running is one of the most popular forms of physical activity around the world. It can be practiced almost everywhere and requires mainly a pair of "appropriate" running shoes. However, the term appropriate is ambiguous, and the properties of running footwear have always generated hot debates among clinicians, coaches, and athletes, whatever the level of practice. As the main interface between the runner's foot and the ground, the shoe potentially plays an important role in managing repetitive external mechanical loads applied to the musculoskeletal system and, thus, in injury prevention. Consequently, over the last decades, running shoes have been prescribed based on matching shoe features to foot morphology. This strategy aligns with the popular belief that footwear is one of the main extrinsic factors influencing running-related injury risk. Despite a seemingly sound strategy for shoe prescription and constant progress in running-footwear technology, the injury rate remains high. Therefore, our aim in this narrative literature review is to clarify whether the prescription of appropriate footwear to prevent injury in running is evidence based, the result of logical fallacy, or just a myth. The literature presented in this review is based on a nonsystematic search of the MEDLINE database and focuses on work investigating the effect of shoe features on injury risk in runners. In addition, key elements for a proper understanding of the literature on running footwear and injury risk are addressed. In this literature review, we outline (1) the main risk factors and the mechanisms underlying the occurrence of running-related injury, (2) important methodologic considerations for generating high-level evidence, (3) the evidence regarding the influence of running-shoe features on injury risk, (4) future directions for research, and (5) final general recommendations.

Association between a national public health campaign for physical activity for patients with chronic diseases and the participation in Phase III cardiac rehabilitation in Luxembourg

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National public health campaign may increase participation to Phase III cardiac rehabilitation.

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National public health campaign increases visibility of a website displaying the Phase III cardiac rehabilitation.

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A more integrated and synergized strategic approach may help to sensitize the patients.

Background

A 2-stage national campaign promoting physical activity for patients with chronic diseases (including cardiovascular disease) was implemented in the Grand-Duchy of Luxembourg in 2018. The first stage consisted of national TV and radio advertisements broadcasted from June 15, 2018 to July 29, 2018. The second stage was a promotional mail sent to all medical doctors on September 3, 2018. This study investigated the association between this campaign and the participation of cardiac patients in Phase III cardiac rehabilitation as well as the visibility of a dedicated website (www.sport-sante.lu).

Methods

The daily numbers of participants in the classes of the Phase III cardiac rehabilitation and the visits on www.sport-sante.lu were collected from January 1, 2016 to December 31, 2018. Segmented regression analysis was used to assess the association between the promotional campaign and the participation in the Phase III cardiac rehabilitation as well as the website visibility.

Results

The baseline participation rate, which was 30 participants/day, increased temporarily by 11 (p = 0.0267) and 18 (p = 0.0030) participants/day after the first and second stages of the campaign, respectively. The baseline visit rate on www.sport-sante.lu, which was 12 visits/day, increased temporarily by 20 (p < 0.0001) and 15 (p = 0.0002) visits/day after the first and second stages of the campaign, respectively.

Conclusions

The national public health campaign was associated with a limited increased participation in the Phase III cardiac rehabilitation and the website visibility. However, no conclusion can be drawn about causality due to the long and difficult process from health promotion to patient’s behavior change.

Effect of shoe cushioning on landing impact forces and spatiotemporal parameters during running: results from a randomized trial including 800+ recreational runners

AbstractIn a recent randomized trial including 800+ recreational runners, injury risk was lower in those who received the Soft shoe version compared to those using the Hard version (Hazard ratio = 1.52; 95% Confidence Interval = 1.07-2.16). Here, we investigated the effect of shoe cushioning on ground reaction forces (GRF) and spatiotemporal parameters in the same cohort, with a special focus on Vertical Impact Peak Force (VIPF) and Vertical Instantaneous Loading Rate (VILR). Healthy runners (n = 848) randomly received one of two shoe prototypes that differed only in their cushioning properties (Global stiffness: 61 ± 3 and 95 ± 6 N/mm in the Soft and Hard versions, respectively). Participants were tested on an instrumented treadmill at their preferred running speed. GRF data was recorded over 2 min. VIPF was higher in the Soft shoe group compared to the Hard shoe group (1.53 ± 0.21 vs. 1.44 ± 0.23 BW, respectively; p < 0.001). However, the proportion of steps with detectable VIPF was lower in the Soft shoe group (84 vs. 97%, respectively; p < 0.001) and Time to VIPF was longer (46.9 ± 8.5 vs. 43.4 ± 7.4 milliseconds, respectively; p < 0.001). No significant differences were observed for VILR (60.1 ± 13.8 vs. 58.9 ± 15.6 BW/s for Soft and Hard shoe group, respectively; p = 0.070) or any other kinetic variable. These results show that the beneficial effect of greater shoe cushioning on injury risk in the present cohort is not associated with attenuated VIPF and VILR. These GRF metrics may be inappropriate markers of the shoe cushioning-injury risk relationship, while delayed VIPF and the proportion of steps displaying a VIPF could be more relevant.Trial registration: ClinicalTrials.gov identifier: NCT03115437..

Shoe Cushioning Influences the Running Injury Risk According to Body Mass: A Randomized Controlled Trial Involving 848 Recreational Runners

BACKGROUND

Shoe cushioning is expected to protect runners against repetitive loading of the musculoskeletal system and therefore running-related injuries. Also, it is a common belief that heavier runners should use footwear with increased shock absorption properties to prevent injuries.

PURPOSE

The aim of this study was to determine if shoe cushioning influences the injury risk in recreational runners and whether the association depends on the runner's body mass.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Healthy runners (n = 848) randomly received 1 of 2 shoe prototypes that only differed in their cushioning properties. Global stiffness was 61.3 ± 2.7 and 94.9 ± 5.9 N/mm in the soft and hard versions, respectively. Participants were classified as light or heavy according to their body mass using the median as a cut-off (78.2 and 62.8 kg in male and female runners, respectively). They were followed over 6 months regarding running activity and injury (any physical complaint reducing/interrupting running activity for at least 7 days). Data were analyzed through time-to-event models with the subhazard rate ratio (SHR) and their 95% confidence interval (CI) as measures of association. A stratified analysis was conducted to investigate the effect of shoe cushioning on the injury risk in lighter and heavier runners.

RESULTS

The runners who had received the hard shoes had a higher injury risk (SHR, 1.52 [95% CI, 1.07-2.16]), while body mass was not associated with the injury risk (SHR, 1.00 [95% CI, 0.99-1.01]). However, after stratification according to body mass, results showed that lighter runners had a higher injury risk in hard shoes (SHR, 1.80 [95% CI, 1.09-2.98]) while heavier runners did not (SHR, 1.23 [95% CI, 0.75-2.03]).

CONCLUSION

The injury risk was higher in participants running in the hard shoes compared with those using the soft shoes. However, the relative protective effect of greater shoe cushioning was found only in lighter runners.

REGISTRATION

NCT03115437 (ClinicalTrials.gov identifier).

Motivational Interviewing to Increase Physical Activity Behavior in Cancer Patients: A Pilot Randomized Controlled Trials

OBJECTIVE

This pilot randomized controlled trial (RCT) aimed at evaluating the feasibility and potential efficacy of a motivational interviewing (MI) intervention to increase physical activity (PA) behavior in cancer patients.

METHODS

Participants were randomly assigned to an experimental group with standard care plus 12 MI sessions within 12 weeks or a control group with standard care only. The number of recruited participants and the modality of recruitment were recorded to describe the reach of the study. The acceptability of the study was estimated using the attrition rate during the intervention phase. The potential efficacy of the intervention was evaluated by analyzing the PA behavior.

RESULTS

Twenty-five participants were recruited within the 16-month recruitment period (1.6 participants per month). Five participants (38.5%) from the experimental group (n = 13) and one participant (8.3%) from the control group (n = 12) dropped out of the study before the end of the intervention phase. No group by time interaction effect for PA behavior was observed at the end of the intervention.

CONCLUSION

Due to the low recruitment rate and compliance, no conclusion can be drawn regarding the efficacy of MI to increase PA behavior in cancer patients. Moreover, the current literature cannot provide any evidence on the effectiveness of MI to increase PA in cancer survivors. Future RCTs should consider that the percentage of uninterested patients to join the study may be as high as 60%. Overrecruitment (30% to 40%) is also recommended to accommodate the elevated attrition rate.

Randomised controlled trials (RCTs) in sports injury research: authors—please report the compliance with the intervention

Background

In randomised controlled trials (RCTs) of interventions that aim to prevent sports injuries, the intention-to-treat principle is a recommended analysis method and one emphasised in the Consolidated Standards of Reporting Trials (CONSORT) statement that guides quality reporting of such trials. However, an important element of injury prevention trials—compliance with the intervention—is not always well-reported. The purpose of the present educational review was to describe the compliance during follow-up in eight large-scale sports injury trials and address compliance issues that surfaced. Then, we discuss how readers and researchers might consider interpreting results from intention-to-treat analyses depending on the observed compliance with the intervention.

Methods

Data from seven different randomised trials and one experimental study were included in the present educational review. In the trials that used training programme as an intervention, we defined full compliance as having completed the programme within ±10% of the prescribed running distance (ProjectRun21 (PR21), RUNCLEVER, Start 2 Run) or time-spent-running in minutes (Groningen Novice Running (GRONORUN)) for each planned training session. In the trials using running shoes as the intervention, full compliance was defined as wearing the prescribed running shoe in all running sessions the participants completed during follow-up.

Results

In the trials that used a running programme intervention, the number of participants who had been fully compliant was 0 of 839 (0%) at 24-week follow-up in RUNCLEVER, 0 of 612 (0%) at 14-week follow-up in PR21, 12 of 56 (21%) at 4-week follow-up in Start 2 Run and 8 of 532 (1%) at 8-week follow-up in GRONORUN. In the trials using a shoe-related intervention, the numbers of participants who had been fully compliant at the end of follow-up were 207 of 304 (68%) in the 21 week trial, and 322 of 423 (76%), 521 of 577 (90%), 753 of 874 (86%) after 24-week follow-up in the other three trials, respectively.

Conclusion

The proportion of runners compliant at the end of follow-up ranged from 0% to 21% in the trials using running programme as intervention and from 68% to 90% in the trials using running shoes as intervention. We encourage sports injury researchers to carefully assess and report the compliance with intervention in their articles, use appropriate analytical approaches and take compliance into account when drawing study conclusions. In studies with low compliance, G-estimation may be a useful analytical tool provided certain assumptions are met.

Physical activity promotion in primary care: a Utopian quest?

The health benefits of physical activity (PA) are acknowledged and promoted by the scientific community, especially within primary care. However, there is little evidence that such promotion is provided in any consistent or comprehensive format. Brief interventions (i.e. discussion, negotiation or encouragement) and exercise referral schemes (i.e. patients being formally referred to a PA professional) are the two dominant approaches within primary care. These cost-effective interventions can generate positive changes in health outcomes and PA levels in inactive patients who are at increased risk for non-communicable diseases. Their success relies on the acceptability and efficiency of primary care professionals to deliver PA counselling. To this end, appropriate training and financial support are crucial. Similarly, human resourcing and synergy between the different stakeholders must be addressed. To obtain maximum adherence, specific populations should be targeted and interventions adapted to their needs. Key enablers include motivational interviewing, social support and multi-disciplinary approaches. Leadership and lines of accountability must be clearly delineated to ensure the success of the initiatives promoting PA in primary care. The synergic and multisectoral action of several stakeholders, especially healthcare professionals, will help overcome physical inactivity in a sustainable way.

Correction to: Rotational profile alterations after anatomic posterolateral corner reconstructions in multiligament injured knees

The original article can be found online.

Intrahepatic diffuse periportal enhancement patterns on hepatobiliary phase gadoxetate disodium-enhanced liver MR images: Do they correspond to periportal hyperintense patterns on T2-weighted images?

The purpose of this study was to investigate the findings of diffuse periportal enhancement in the liver on hepatobiliary phase gadoxetate disodium-enhanced magnetic resonance images by comparing with the finding of periportal hyperintensity on T2-weighted images and to reveal their clinical significance.Nineteen consecutive patients with diffuse periportal enhancement on hepatobiliary phase images constituted the study population. The intrahepatic diffuse periportal enhancement finding was assessed on whether it corresponded to periportal hyperintense patterns on T2-weighted images or not in the location, and the cases were classified into 2 groups according to this characteristic. Signal intensities at the periportal areas were also assessed on T1-, T2-, diffusion-weighted and dynamic images. Furthermore, possible associations between these image findings and the final diagnoses were explored.In 7 of the 19 patients, periportal enhancement area corresponded with the periportal hyperintensity area on T2-weighted images. In the remaining 12 patients, the finding of periportal T2-hyperintensity was absent or the periportal enhancement differed from the periportal T2-hyperintensity in the location. Diseases of the former group comprised autoimmune hepatitis, acute exacerbation of chronic hepatitis and acute alcoholic steatohepatitis, and those of the latter group primary sclerosing cholangitis, autoimmune hepatitis-primary biliary cirrhosis overlap syndrome, and liver cirrhosis with miscellaneous etiology.Diffuse periportal enhancement during the hepatobiliary phase did not always correspond to periportal hyperintensity on T2-weighted images. In the classification based on whether enhancement area corresponded or not, each enhancement pattern appeared in different groups of liver diseases. Specifically, the former (corresponding) was associated with active inflammation such as hepatitis and the latter (not corresponding) was predominantly associated with a chronic change such as cirrhosis. Appropriate recognition of these periportal enhancement patterns may contribute to the improved diagnosis of diffuse liver diseases.

Time-to-event analysis for sports injury research part 1: time-varying exposures

BACKGROUND

'How much change in training load is too much before injury is sustained, among different athletes?' is a key question in sports medicine and sports science. To address this question the investigator/practitioner must analyse exposure variables that change over time, such as change in training load. Very few studies have included time-varying exposures (eg, training load) and time-varying effect-measure modifiers (eg, previous injury, biomechanics, sleep/stress) when studying sports injury aetiology.

AIM

To discuss advanced statistical methods suitable for the complex analysis of time-varying exposures such as changes in training load and injury-related outcomes.

CONTENT

Time-varying exposures and time-varying effect-measure modifiers can be used in time-to-event models to investigate sport injury aetiology. We address four key-questions (i) Does time-to-event modelling allow change in training load to be included as a time-varying exposure for sport injury development? (ii) Why is time-to-event analysis superior to other analytical concepts when analysing training-load related data that changes status over time? (iii) How can researchers include change in training load in a time-to-event analysis? and, (iv) Are researchers able to include other time-varying variables into time-to-event analyses? We emphasise that cleaning datasets, setting up the data, performing analyses with time-varying variables and interpreting the results is time-consuming, and requires dedication. It may need you to ask for assistance from methodological peers as the analytical approaches presented this paper require specialist knowledge and well-honed statistical skills.

CONCLUSION

To increase knowledge about the association between changes in training load and injury, we encourage sports injury researchers to collaborate with statisticians and/or methodological epidemiologists to carefully consider applying time-to-event models to prospective sports injury data. This will ensure appropriate interpretation of time-to-event data.

Time-to-event analysis for sports injury research part 2: time-varying outcomes

BACKGROUND

Time-to-event modelling is underutilised in sports injury research. Still, sports injury researchers have been encouraged to consider time-to-event analyses as a powerful alternative to other statistical methods. Therefore, it is important to shed light on statistical approaches suitable for analysing training load related key-questions within the sports injury domain.

CONTENT

In the present article, we illuminate: (i) the possibilities of including time-varying outcomes in time-to-event analyses, (ii) how to deal with a situation where different types of sports injuries are included in the analyses (ie, competing risks), and (iii) how to deal with the situation where multiple subsequent injuries occur in the same athlete.

CONCLUSION

Time-to-event analyses can handle time-varying outcomes, competing risk and multiple subsequent injuries. Although powerful, time-to-event has important requirements: researchers are encouraged to carefully consider prior to any data collection that five injuries per exposure state or transition is needed to avoid conducting statistical analyses on time-to-event data leading to biased results. This requirement becomes particularly difficult to accommodate when a stratified analysis is required as the number of variables increases exponentially for each additional strata included. In future sports injury research, we need stratified analyses if the target of our research is to respond to the question: 'how much change in training load is too much before injury is sustained, among athletes with different characteristics?' Responding to this question using multiple time-varying exposures (and outcomes) requires millions of injuries. This should not be a barrier for future research, but collaborations across borders to collecting the amount of data needed seems to be an important step forward.

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?

Ramp lesions associated with ACL injuries are more likely to be present in contact injuries and complete ACL tears

PURPOSE

The purpose of this study was to analyse patient and injury characteristics as well as arthroscopic findings in a prospective cohort of ACL-injured patients with or without an associated ramp lesion.

METHODS

Two hundred and twenty-four patients undergoing a primary (n = 196) or revision (n = 28) ACL reconstruction were included. The presence of a ramp lesion was determined by a systematic arthroscopic inspection of the posteromedial compartment. Chi-square tests were used to compare the population of ACL-injured patients with and without a ramp lesion regarding sex, age, body mass index, previous ACL injuries, sport before injury, and injury characteristics. Significance was set at p < 0.05.

RESULTS

Fifty-three out of 224 patients had a ramp lesion (24%). The presence of the latter was not related to any of the analysed patient characteristics. The prevalence of the lesion was higher in contact injuries (n = 19; 41%) compared with non-contact injures (n = 34; 19%; p < 0.001). It was higher in patients with complete ACL ruptures (n = 49; 27%) as opposed to partial ruptures (n = 1; 4%; p = 0.01). A patient was 2.98 [95% CI 1.49-5.98] times more likely to have a ramp lesion if the ACL injury was declared to have been caused by direct contact and 8.71 [95% CI 1.15-66.12] times more likely if the ACL tear was complete.

CONCLUSION

Ramp lesions may be anticipated in almost one out of four patients undergoing ACL reconstruction, especially if a patient sustained a contact injury and in the presence of a complete ACL tear.

LEVEL OF EVIDENCE

III.

Effect of cognitive challenge on the postural control of patients with ACL reconstruction under visual and surface perturbations

Our study aimed to evaluate the effect of cognitive challenge on double-leg postural control under visual and surface perturbations of patients with anterior cruciate ligament reconstruction (ACLR) cleared to return to sport. Double-leg stance postural control of 19 rehabilitated patients with ACLR (age: 24.8 ± 6.7 years, time since surgery: 9.2 ± 1.6 months) and 21 controls (age: 24.9 ± 3.7 years) was evaluated in eight randomized situations combining two cognitive (with and without silent backward counting in steps of seven), two visual (eyes open, eyes closed) and two surface (stable support, foam support) conditions. Sway area and sway path of the centre of foot pressure were measured during three 20-s recordings for each situation. Higher values indicated poorer postural control. Generally, postural control of patients with ACLR and controls was similar for sway area and sway path (p > 0.05). The lack of visual anchorage and the disturbance of the plantar input by the foam support increased sway area and sway path (p < 0.001) similarly in both groups. The addition of the cognitive task decreased sway area and sway path (p < 0.001) similarly in both groups. Patients with ACLR who recently completed their rehabilitation have normalized postural control during double-leg stance tests. The use of a dual task paradigm under increased task complexity modified postural control, but in a similar way in patients with ACLR than in healthy controls. Double-leg stance tests, even under challenging conditions, are not sensitive enough to reveal postural control differences between rehabilitated patients with ACLR and controls.

Side-to-side asymmetries in landing mechanics from a drop vertical jump test are not related to asymmetries in knee joint laxity following anterior cruciate ligament reconstruction

PURPOSE

Asymmetries in knee joint biomechanics and increased knee joint laxity in patients following anterior cruciate ligament reconstruction (ACLR) are considered risk factors for re-tear or early onset of osteoarthritis. Nevertheless, the relationship between these factors has not been established. The aim of the study was to compare knee mechanics during landing from a bilateral drop vertical jump in patients following ACLR and control participants and to study the relationship between side-to-side asymmetries in landing mechanics and knee joint laxity.

METHODS

Seventeen patients following ACLR were evaluated and compared to 28 healthy controls. Knee sagittal and frontal plane kinematics and kinetics were evaluated using three-dimensional motion capture (200 Hz) and two synchronized force platforms (1000 Hz). Static anterior and internal rotation knee laxities were measured for both groups and legs using dedicated arthrometers. Group and leg differences were investigated using a mixed model analysis of variance. The relationship between side-to-side differences in sagittal knee power/energy absorption and knee joint laxities was evaluated using univariate linear regression.

RESULTS

A significant group-by-leg interaction (p = 0.010) was found for knee sagittal plane energy absorption, with patients having 25% lower values in their involved compared to their non-involved leg (1.22 ± 0.39 vs. 1.62 ± 0.40 J kg^-1). Furthermore, knee sagittal plane energy absorption was 18% lower at their involved leg compared to controls (p = 0.018). Concomitantly, patients demonstrated a 27% higher anterior laxity of the involved knee compared to the non-involved knee, with an average side-to-side difference of 1.2 mm (p < 0.001). Laxity of the involved knee was also 30% higher than that of controls (p < 0.001) (leg-by-group interaction: p = 0.002). No relationship was found between sagittal plane energy absorption and knee laxity.

CONCLUSIONS

Nine months following surgery, ACLR patients were shown to employ a knee unloading strategy of their involved leg during bilateral landing. However, this strategy was unrelated to their increased anterior knee laxity. Side-to-side asymmetries during simple bilateral landing tasks may put ACLR patients at increased risk of second ACL injury or early-onset osteoarthritis development. Detecting and correcting asymmetric landing strategies is highly relevant in the framework of personalized rehabilitation, which calls for complex biomechanical analyses to be applied in clinical routine.

LEVEL OF EVIDENCE

III.