Background Trail running is popular worldwide, but there is no preventive intervention for running-related injury (RRI).
Aim To evaluate the effectiveness of adding online tailored advice (TrailS6 ) to general advice on (1) the prevention of RRIs and (2) the determinants and actual preventive behaviour in Dutch trail runners.
Methods Two-arm randomised controlled trial over 6 months. 232 trail runners were randomly assigned to an intervention or control group. All participants received online general advice on RRI prevention 1 week after baseline. Every 2 weeks, participants in the intervention group received specific advice tailored to their RRI status. The control group received no further intervention. Bayesian mixed models were used to analyse the data.
Results Trail runners in the intervention group sustained 13% fewer RRIs compared with those in the control group after 6 months of follow-up (absolute risk difference −13.1%, 95% Bayesian highest posterior credible interval (95% BCI) −23.3 to −3.1). A preventive benefit was observed in one out of eight trail runners who had received the online tailored advice for 6 months (number needed to treat 8, 95% BCI 3 to 22). No significant between-group difference was observed on the determinants and actual preventive behaviours.
Conclusions Online tailored advice prevented RRIs among Dutch trail runners. Therefore, online tailored advice may be used as a preventive component in multicomponent RRI prevention programmes. No effect was observed on determinants and actual preventive behaviours.
Trial registration number The Netherlands National Trial Register (NTR5431).
- evidence-based practice
- health behavior
- risk reduction behavior
- sports injuries
- comparative effectiveness research
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- evidence-based practice
- health behavior
- risk reduction behavior
- sports injuries
- comparative effectiveness research
The world pandemic of physical inactivity is worrisome, and the reduction of its prevalence and burden is considered a public health priority.1–3 Running is a very popular mode of physical activity worldwide.4 5 Its related health benefits are well described in the literature,6–8 and there is evidence suggesting that implementing running as a means of promoting physical activity is cost-effective.9 10 According to VeiligheidNL (the Dutch Consumer Safety Institute), running was the third most practised sport in the Netherlands in 2013, with around 2.1 million people.5 A mode of running known as trail running is quickly gaining in popularity.11 Trail running consists of running in the outdoors, mainly on unpaved, rugged, muddy and/or hilly/mountain terrains.11 To illustrate the spike in popularity, according to MudSweatTrails (the largest trail running community in the Netherlands), there was no trail running event in the Netherlands and Belgium in 2010, and there were over 150 in 2015.
Nonetheless, the risk of running-related injuries (RRIs) is a matter of concern because RRIs may lower the motivation to run and RRIs can also reach severity levels that might lead to dropping out of running practice.11 12 This counteracts efforts to increase physical activity levels.3 The prevalence proportion of RRIs in Dutch trail runners is estimated at 22.4% (95% frequentist confidence interval (CI) 20.9 to 24.0), and the injury rate is 10.7 RRIs per 1000 hours of running (95% CI 9.4 to 12.1).11 Despite the burden of RRIs to the runners and for society,11–13 there is no substantial evidence on interventions to prevent RRIs.14–17 This is worrisome because RRI is an avoidable side effect of running, and therefore, preventive efforts are warranted.
Tailored online interventions are promising in promoting preventive behaviour in runners.18 They are attractive due to their convenience, availability, interactivity, relative low cost to develop and implement and their ability to reach a large number of people.18 19 There are no randomised controlled trials aimed at investigating the effectiveness of online tailored interventions on the prevention of RRIs, and the effects of such interventions on the determinants and actual preventive behaviour in periods longer than 3 months have never been described.18 In addition, there is no evidence on interventions to prevent RRIs in trail runners. Therefore, the purpose of this study was to evaluate the effectiveness of adding online tailored advice to general advice on the determinants and actual preventive behaviour and on the prevention of RRIs in Dutch trail runners.
This study was a two-arm pragmatic20 randomised controlled trial over 6 months with blind assessment and blind delivery of intervention. The inclusion of individuals in the study was performed electronically, based on the eligibility criteria procedure implemented in the baseline questionnaire. This procedure ensured that the allocation of the participants in the intervention and control groups was concealed. After the inclusion, all participants were randomly assigned to the intervention or control group according to a computer-generated simple randomisation scheme. The assessment and the delivery of the intervention were blinded as all data were collected via an online questionnaire, and the intervention was delivered online through the website of the project, ensuring no influence or bias of healthcare providers or assessors of outcomes. This study was approved by the medical ethics committee of the VU University Medical Center Amsterdam and has been prospectively registered in the Netherlands National Trial Register (NTR5431).
The sample size was estimated based on calculations for longitudinal studies with repeated measurements.21 The difference in change from baseline for warming up found in a previous study (13% in the intervention and 4% in the control group) investigating the effects of an online tailored intervention in runners was used as a reference effect size for preventive behaviours.18 The reference value for the mean proportion of trail runners sustaining RRIs (22.4%) was based on a previous prospective cohort study conducted with the same source population.11 The hypothesised reduction in the proportion of trail runners sustaining RRIs was 20% in the intervention and 10% in the control group, on average. Considering an α of 0.05, power of 0.8, three repeated measurements for preventive behaviours (at baseline and at 2 and 6 months after baseline), 13 repeated measurements for RRI (every 2 weeks during 6 months), a within-person correlation of 0.311 and a response rate of 70%,11 12 the sample size was estimated at 105 participants for each group for preventive behaviours (total of 210 participants) and 92 participants for each group for RRI (total of 184 participants).
This study was composed of a sample of Dutch trail runners registered in the MudSweatTrails database (http://www.mudsweattrails.nl). In order to assure that the participants were active in trail running, all participants of a recent trail running event organised by MudSweatTrails at the time of the recruitment (ie, ‘Salomon Koning van Spanje Trail’ held in May 2015) were invited to participate (n=1327). This trail is a traditional Dutch event that covers eight trail running races with distances varying from 15 to 62 km. In addition, the participants of a previous observational study conducted with the same source population were also invited to participate (n=185).11 Individuals who agreed to participate through online informed consent, aged 18 years or over, involved in trail running and who completed the baseline questionnaire were eligible to participate.
Development of the intervention
The five steps of the Knowledge Transfer Scheme (KTS)22 were followed in order to develop an intervention aimed at preventing RRIs in trail runners (table 1). The KTS process resulted in an evidence-based and practice-based online intervention, tailoring advice towards RRI prevention taking into account the RRI profile provided by the Oslo Sports Trauma Research Centre (OSTRC) Questionnaire on Health Problems.23 The online tailored intervention was named TrailS6 (online supplementary material appendix S1).
Supplementary file 1
One week after baseline, all participants received a general advice towards RRIs prevention. During the follow-up, tailored advice was delivered based on the RRI classification generated by the OSTRC questionnaire, that is, (1) no RRI, (2) non-substantial RRI or (3) substantial RRI (defined as RRIs resulting in moderate or major reductions in training volume, moderate or major reductions in running performance or complete inability to run).11 12 23 Participants who reported no RRI received advice aimed at maintaining their uninjured status (ie, primary prevention24). Participants who reported non-substantial RRIs received tailored advice aimed at promoting a fast recovery and to prevent the non-substantial RRI to become a substantial RRI (ie, secondary prevention24). Participants who reported substantial RRIs received tailored advice in order to prevent further consequences (ie, long-term burden and prolonged absence from running), permanent damage due to RRIs and subsequent RRIs (ie, tertiary prevention24).
The advice was instantaneously and automatically delivered after the completion of the RRI questionnaire by directing the participant to a web page hosted by the study website. This procedure was repeated every 2 weeks in order to monitor the RRI status and to adapt the tailored advice accordingly. Adherence to the intervention was assessed asking the participants which components of the tailored advice received in the last 2-week period they used.25
The participants assigned to the control group received a general advice towards RRIs prevention 1 week after baseline. This advice was equal and in the same form as received by the intervention group at this stage. The control group did not receive any further advice during the follow-up (figure 1). The general advice delivered to the control group only once (ie, 1 week after baseline) may be considered ‘usual care’26 because these are the pieces of advice that the trail runners usually receive from trainers, healthcare professionals, friends, online sources, and so on, without a systematic and prospective tailoring and/or reminder.
After giving informed consent, a secured link to an online baseline questionnaire was sent by email to the participants. This questionnaire asked about demographics, education level, running experience, trail running experience, history of RRIs (last 12 months) and current RRIs.
Preventive behavioural questionnaire
The Theory of Planned Behaviour was used as the conceptual model of behaviour in this study.27 28 The determinants of performing the intervention and the behaviours towards RRI prevention were assessed at baseline, 2 months after baseline and at the end of the follow-up (online supplementary material appendix S2).
Preventive behaviour was assessed by a multiple-choice question. Five-point Likert scales were used to assess the determinants of performing the intervention. A single item was used to assess intention and subjective norm. Attitude was assessed by three items, and the average was used in the analysis.29 Perceived behavioural control was assessed by two items and the average was used in the analysis.29 30
A secured link to an online RRI questionnaire was sent by email every 2 weeks. The aims of this questionnaire were to collect information on running exposure and any complaint experienced in the preceding 2 weeks and to deliver the online tailored advice based on the RRI classification generated by the translated Dutch version of the OSTRC questionnaire.23 31 RRI was defined as any disorder of the musculoskeletal (eg, muscles, tendons, ligaments, nerves and bones) or integumentary (eg, blisters and nail injuries) systems, or concussions experienced or sustained by an individual during participation in running. A recurrent RRI was defined as an RRI at the same location and of the same type of the index RRI, even if it concerned reinjuries (after full recovery) or exacerbations (no full recovery).11 12 32 One investigator, who is also a physiotherapist (LCH), evaluated each self-reported complaint case by case. When the description of the complaint reported by the participant matched the RRI definition, the investigator classified the complaint as an RRI. The RRI registration and classification were performed according to previous studies on RRIs that used the OSTRC questionnaire, and the methods used can be found elsewhere.11 12
All analyses were performed in R 3.3.2 (R Foundation for Statistical Computing, Vienna, Austria) and followed the intention-to-treat principle. Descriptive analyses were performed to summarise the baseline data. Follow-up data were summarised using Bayesian linear mixed models (BLMMs) and Bayesian linear probability mixed models (BLPMMs)33 in order to account for repeated measurements. The injury rate was estimated using Bayesian inference,34 and the results were expressed as the number of RRIs per 1000 hours of running and its 95% Bayesian highest posterior density credible interval (95% BCI).
The main outcomes of this study were (1) the determinants of performing the intervention (intention, attitude, subjective norm and perceived behavioural control) as continuous variables, (2) preventive behaviours (online supplementary material appendix S2) as binary outcomes and (3) RRI as a binary outcome (ie, ‘0’=no RRI; ‘1’=RRI).
The effects of the intervention on the main outcomes were analysed as follows: (1) the determinants of performing the intervention were analysed using BLMM, (2) preventive behaviours were analysed using BLPMM and (3) the prevention of RRIs was analysed using BLPMM. Group, time and the interaction term composed of group and time were used as independent variables. Non-informative priors were used for the fixed35 and random effects.36 Calculations were based on sampling from the posterior distribution using the No-U-Turn Sampler37 with five chains, 20 000 interactions, and leaving out the 5000 initial interactions of each chain.
The Bayes factor (BF) was estimated by calculating the posterior probability of a preventive effect, divided by the posterior probability of no preventive effect.38 Preventive effects were defined as mean differences >0 for the BLMM models on determinants of performing the intervention, absolute risk differences (ARDs) >0 for the BLPMM models on preventive behaviours and ARD <0 for the BLPMM model on the prevention of RRIs. The strength of evidence favouring a preventive effect was classified as ‘barely worth mentioning’ (BF≤3), ‘positive’ (3<BF≤20), ‘strong’ (20<BF≤150) or ‘very strong’ (BF>150).38 The results were considered significant when the 95% BCI did not contain the null effect and when the BF >3 (ie, substantial evidence supporting the preventive effect in favour of the intervention group).39 The number needed to treat (NNT) was estimated by Bayesian inference for the significant results.40
Flow of participants, running exposure and RRI characteristics
From the 1512 trail runners who were invited to participate, 232 (15.3%) responded and were included in the study. The baseline results are summarised in table 2. The flow of participants can be found in figure 1. During the follow-up, 10 participants (four in the intervention and six in the control group) dropped out of the study. However, the data collected of these participants until the time they dropped out were included in the analysis. The median of the response rate during the follow-up was 78.6% (25% to 75% interquartile range (IQR) 74.8–85.2) for the intervention group and 83.9% (IQR 74.1–89.3) for the control group.
A summary of the average running exposure and RRI characteristics can be found in table 3. A total of 87 participants (75.7%) reported 135 RRIs in the intervention group, and 91 (77.8%) reported 151 RRIs in the control group. Most RRIs were overuse injuries, either for the intervention (74.1%, n=100) or the control group (74.2%, n=112). A breakdown list with all RRIs reported per group can be found in the online supplementary material appendix S3.
Effects of the intervention on determinants of behaviour
The intervention presented a trend in decreasing the level of intention, attitude, subjective norm and perceived behavioural control towards performing the intervention after 2 and 6 months of follow-up, although the 95% BCI contained the null effect and the BFs suggested ‘barely worth mentioning’ preventive effects (table 4). Therefore, the effects on the determinants of performing the intervention are considered non-significant.
Effects of the intervention on preventive behaviours
The intervention presented a trend in increasing the probability of performing three out of seven preventive behaviours included in the intervention (warming up, cooling down and the use of specialised trail running shoes) after 2 and 6 months of follow-up, although the 95% BCI contained the null effect (table 4). Therefore, the effects of the intervention on preventive behaviours are considered non-significant.
Preventive effects of the intervention on RRIs
There was a ‘very strong’ evidence (BF 194.3) supporting a preventive effect on RRIs after 2 and 6 months of follow-up (table 4). Also, the 95% BCI for the ARD estimates did not contain the null effect. Therefore, the preventive effect of the online tailored advice on RRIs was significant. The NNT after 2 and 6 months of follow-up was 30 (95% BCI 14 to 87) and 8 (95% BCI 3 to 22), respectively.
Adherence to the intervention
The results regarding the adherence of the intervention group to the online tailored advice can be found in table 5. The adherence to at least one advice and to the ‘longer recovery period’ advice was higher for those reporting substantial RRIs than for those reporting no RRI. The percentage of participants taking no advice was lower for the participants reporting substantial RRIs than for those reporting no RRI. The ‘reduction of running exposure’ advice presented a lower adherence for those reporting no RRI than for those reporting non-substantial and substantial RRIs. The adherence to the ‘medical attention’ advice was higher for those reporting substantial RRIs than for those reporting non-substantial RRIs.
Effectiveness of the intervention on determinants and actual preventive behaviour
The evidence supporting a change on the determinants of performing the intervention and on promoting preventive behaviours towards RRI prevention was considered non-significant after 2 and 6 months of follow-up. A recent study found a statistically significant effect after 3 months of follow-up of an online tailored intervention on determinants (intention, attitude and risk perception) and on actual preventive behaviour (ie, warming up before training, before competitions and performing a proper workout regimen) in Dutch runners.18 These conflicting results may be explained by differences in the content (eg, informative videos) and in the delivery of the intervention (eg, exposure to the intervention of 30 min) evaluated in the study of Adriaensens et al.18 Also, the delivery of general advice to the control group at the beginning of the current study could have suppressed the effects of the intervention on preventive behaviours.
Effectiveness of the intervention on RRIs
In contrast to no effect on preventive behaviour, online tailored advice was effective for the prevention of RRIs after 6 months of follow-up. The mechanism of the preventive effect of the online tailored advice on the prevention of RRIs cannot be certainly determined in a behavioural perspective, while the intervention was not effective in changing preventive behaviour. Maybe 6 months of implementation of online tailored advice was too short to yield effects on individual preventive behaviours. Nonetheless, the small and/or non-significant effects on several preventive behaviours combined (eg, warming up, cooling down and the use of specialised trail running shoes) could have resulted in the significant preventive effect on RRIs.
Strengths and limitations of this study
This was the first study to investigate the effects of an online intervention to prevent RRIs. The allocation of the participants to the intervention and control groups was concealed, reducing the risk of selection bias.41 The assessment of the outcomes and the delivery of the intervention were blinded, reducing the risk of detection bias.41 Reducing the risk of bias increases the internal validity of the results.42 The adherence of each component of the intervention was reported in order to tailor future prevention programmes to the components with higher adherence, or to create strategies to increase the adherence of those less performed. This study can be classified as a pragmatic randomised controlled trial, in other words an effectiveness trial, due to its characteristics such as20 26 (1) a non-restrictive eligibility criteria, (2) the participatory approach applied during the development of the TrailS6 intervention, (3) the intervention flexibility (ie, the participants could choose to perform the most suitable advice to them), (4) the ‘usual care’ characteristic of the control group (explained in the methods), (5) the adherence flexibility to the intervention (a reality in ‘real world’) and (6) the intention-to-treat analyses.
Although the sample of trail runners included in this study is likely to be representative of the Dutch trail running community,11 this study was composed of a convenience sample. Blinding of participants was not possible because of the impossibility to develop a sham intervention mimicking the online tailored intervention evaluated in this study. Because the effects of the intervention included primary, secondary and tertiary prevention,24 specific effects on each prevention level might be latent in the results. However, this study had no sufficient power for a subgroup analysis in order to investigate the effects of the intervention in each level of prevention. Last but not least, the implementation of a minimal intervention in the control group may have resulted in an attenuation of the effectiveness of the online tailored intervention.
Implications for practice and recommendations
The strength of evidence supporting a significant preventive effect of online tailored advice on RRIs was classified as ‘very strong’, suggesting that its implementation in practice may be supported by this evidence. This is relevant because online interventions are inexpensive, easy to implement and reachable for a large number of people.18 19 Tailored advice may constitute a basic preventive component in a multicomponent prevention programme, including, for example, supervised strengthening and proprioceptive training.43 44 Adding the preventive effects of these interventions may enhance the likelihood of preventing RRIs. Therefore, online tailored advice may be used as a tool to RRI prevention, but maybe it should not be used as a stand-alone approach. However, multicomponent interventions aimed at preventing RRIs still need to be developed and evaluated in randomised controlled trials.
The average adherence to the intervention found in the current study varied from 66.6% to 90.1%, suggesting that online tailored advice may be successfully implemented in practice.45 Nonetheless, future efforts on adapting, developing or implementing tailored advice on RRI prevention should focus on the components with the highest adherence presented in this study and/or develop additional strategies to enhance the components with lower adherence. Adding informative videos and/or online instantaneous feedback with human interaction (eg, live video consultations) may be suggestions to increase adherence. In addition, long-term effects (≥12 months) and implementation outcomes of online tailored interventions should be investigated.
There was a ‘very strong’ evidence (BF 194.3) supporting a significant (ARD −13.1%, 95% BCI −23.3 to −3.1) preventive effect (NNT 8, 95% BCI 3 to 22) of adding online tailored advice to general advice on the prevention of RRIs after 6 months of follow-up. Therefore, online tailored advice may be used as a preventive component in RRI prevention programmes. No effect was observed on determinants and actual preventive behaviours towards RRI prevention.
What are the findings?
The addition of online tailored advice adjusted every 2 weeks for the running-related injury (RRI) classification generated by the Oslo Sports Trauma Research Centre Questionnaire on Health Problems (ie, no injury, non-substantial injury or substantial injury) to general advice was effective on preventing RRIs when compared with online general advice given only at baseline.
The addition of online tailored advice to general advice seems to be ineffective for changing individual preventive behaviours towards the prevention of RRIs when compared with online general advice given only at baseline.
How might it impact on clinical practice in the future?
Online tailored advice may constitute a preventive component in multicomponent prevention programmes in order to enhance the likelihood of preventing RRIs.
One out of eight trail runners receiving online tailored advice (TrailS6 ) every 2 weeks rather than receiving general advice given only at baseline may benefit from an RRI preventive effect over 6 months.
The authors wish to thank MudSweatTrails and Marc Weening for their assistance during the recruitment, and all trail runners who participated in this study.
Contributors All authors were involved in the conceptualisation, design and conduction of the study. LCH cleaned, analysed and interpreted the data. All authors were involved in the drafting and revision of the manuscript for intellectual content, and all approved the final version of the article. All authors had full access to the data (including statistical reports and tables) and can take responsibility for the integrity of the data and the accuracy of the data analysis.
Funding LCH was granted with a CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) PhD scholarship, process number 0763/12-8, Ministry of Education of Brazil.
Competing interests WvM is a director-share holder of VU University Medical Center Amsterdam spin-off company Evalua Nederland (http://www.evalua.nl) and non-executive board member of Arbo Unie (http://www.arbounie.nl). Both companies operate on the Dutch occupational healthcare market, and they have no relationship with the TrailS6 intervention.
Ethics approval This study was approved by the medical ethics committee of the VU University Medical Center Amsterdam, the Netherlands.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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