The DANO-RUN study was a 1-year prospective follow-up study aiming at characterizing risk factors for injury in novice runners. Present paper describes a sub-analysis of the injured novice runners included in the DANO-RUN study. The procedure for enrolment, inclusion and exclusion criteria and main purpose of the DANO-RUN study has been presented elsewhere[5] –[7] . All participants provided informed written consent prior to inclusion and the research was conducted in accordance with the Helsinki Declaration. The Scientific committee, Central Denmark Region evaluated the protocol (M-20110114) but waived the request for approval because observational studies, according to the Danish law, do not require an ethical approval. The Danish Data Protection Agency approved the study.
A novice runner was defined as a person who had not been running on a regular basis for the past year. The cut-off to define a regular basis was set at 10 km of the total running distance in all training sessions during the past year prior to inclusion. If a total of 10 km was exceeded a person was ineligible for inclusion. For instance, a person was included if he/she had been running a total of 3 times 2 kilometers in the past year and excluded if he/she had been running 5 times 4 kilometers. A running-related injury was defined as any musculoskeletal complaint of the lower extremity or back caused by running, which restricted the amount of running (distance, duration, pace, or frequency) for at least 1 week. This definition of injury was a modified version of the injury definition used in the studies on novice runners [3] (link), [8] (link), [9] (link). The date of injury occurrence was based on the anamnesis where the injured runner was asked to recall the date at which the symptoms started.
Prior to the study, no consensus-based definition of time to recovery was found. The authors defined recovery from injury as no pain in the affected anatomical location following two consecutive running sessions of at least 500 meters. The time to recovery was calculated as time in days from injury occurrence to complete recovery. In the case a participant was free of pain in activities of daily living but refused to run in order to evaluate on their symptoms, the recovery was defined as the day they were free of pain.
All injured participants attended a clinical examination in case of injury. At the examination, the participant was examined and diagnosed, preferably no later than 1 week after the participant had requested an examination. In most examinations (more than 80%), at least two physiotherapists (of four assisting in the study) diagnosed the injured participant based on a consensus agreement. A standardized examination procedure was used in each of the following anatomical locations: foot/ankle, lower leg, knee, thigh, hip and back. Furthermore, guidelines for diagnostic criteria were used to classify the injuries into specific diagnoses/types of injuries. These non-validated guidelines were developed by the DANO-RUN research group prior to the study (Material S1 ). At each examination, the injured runner was asked if they believed the injury was caused by running. If they said “yes” the injury was included in the analysis, while the injury was excluded if they said “no”. If they said “no” the injury was not registered in the database and it is, therefore, not possible to present details about these types of injuries.
In case the physiotherapist was unable to diagnose the injured runner at the clinical examination or the participant did not recover as expected after being diagnosed, an additional examination including diagnostic imaging (most often MRI) was performed. Such examination was provided in approximately 25% of all injuries and was always offered if the physiotherapist at the first examination diagnosed injuries like medial meniscal injury, osteoarthritis or stress fractures. The additional examination and diagnostic imaging were performed at the Division of Sports Traumatology at Aarhus University Hospital, Denmark. Based on the clinical examination(s), the diagnoses were registered for all injuries occurring from inclusion in the study and in the following 1-year period. In cases where the examiners (Physiotherapist and medical doctors) were in doubt and the diagnostic imaging was negative, the injury was classified as unknown.
After the clinical examination, all injured participants were followed prospectively and contacted by phone or mail once every 2 to 3 weeks to follow-up on injury status. In case the participants recovered from injury, questions regarding the use of medication (yes/no), treatment assistance from health professional (yes/no), surgical treatment (yes/no) and missed days from work (number) were asked. In addition, participants had to report their motivation to start running again after having had an injury and this information was then dichotomized into: 1) Less motivated or not at all motivated or 2) motivated or very motivated. If a participant completely recovered from injury and sustained an additional running-related injury afterwards, the participant had to attend a clinical examination again. The possibility of clinical examinations was stopped after the participants had been included in the DANO-RUN study for 1-year. The follow-up on injured participants were stopped February 2013, eighteen months after the first participants were enrolled at a baseline investigation and 7 months after the last participants completed follow-up.
Descriptive data were presented as counts and percentage dichotomous or categorical data. Data on time to recovery were presented as medians and the range between minimum and maximum because data on injury were considered non-parametric evaluated by histograms and quartile-quartile plots. Contra wise, data on the log scale was normally distributed. Therefore, the student's t-test was used to test if time to recovery (days) was different between those motivated to take up running again after having had an injury compared with those being less motivated. The Wilcoxon rank sum test was used to test if the time to recovery was different across gender and across age (dichotomized into less than or above 40 years because masters runners typically are defined as persons above 40 and face subtle differences in injury rate and location[10] (link)) because the data were not normally distributed on original scale or on the log scale. All analyses were performed using STATA/SE version 12.1. A result was considered significant at p<0.05.
A novice runner was defined as a person who had not been running on a regular basis for the past year. The cut-off to define a regular basis was set at 10 km of the total running distance in all training sessions during the past year prior to inclusion. If a total of 10 km was exceeded a person was ineligible for inclusion. For instance, a person was included if he/she had been running a total of 3 times 2 kilometers in the past year and excluded if he/she had been running 5 times 4 kilometers. A running-related injury was defined as any musculoskeletal complaint of the lower extremity or back caused by running, which restricted the amount of running (distance, duration, pace, or frequency) for at least 1 week. This definition of injury was a modified version of the injury definition used in the studies on novice runners [3] (link), [8] (link), [9] (link). The date of injury occurrence was based on the anamnesis where the injured runner was asked to recall the date at which the symptoms started.
Prior to the study, no consensus-based definition of time to recovery was found. The authors defined recovery from injury as no pain in the affected anatomical location following two consecutive running sessions of at least 500 meters. The time to recovery was calculated as time in days from injury occurrence to complete recovery. In the case a participant was free of pain in activities of daily living but refused to run in order to evaluate on their symptoms, the recovery was defined as the day they were free of pain.
All injured participants attended a clinical examination in case of injury. At the examination, the participant was examined and diagnosed, preferably no later than 1 week after the participant had requested an examination. In most examinations (more than 80%), at least two physiotherapists (of four assisting in the study) diagnosed the injured participant based on a consensus agreement. A standardized examination procedure was used in each of the following anatomical locations: foot/ankle, lower leg, knee, thigh, hip and back. Furthermore, guidelines for diagnostic criteria were used to classify the injuries into specific diagnoses/types of injuries. These non-validated guidelines were developed by the DANO-RUN research group prior to the study (
In case the physiotherapist was unable to diagnose the injured runner at the clinical examination or the participant did not recover as expected after being diagnosed, an additional examination including diagnostic imaging (most often MRI) was performed. Such examination was provided in approximately 25% of all injuries and was always offered if the physiotherapist at the first examination diagnosed injuries like medial meniscal injury, osteoarthritis or stress fractures. The additional examination and diagnostic imaging were performed at the Division of Sports Traumatology at Aarhus University Hospital, Denmark. Based on the clinical examination(s), the diagnoses were registered for all injuries occurring from inclusion in the study and in the following 1-year period. In cases where the examiners (Physiotherapist and medical doctors) were in doubt and the diagnostic imaging was negative, the injury was classified as unknown.
After the clinical examination, all injured participants were followed prospectively and contacted by phone or mail once every 2 to 3 weeks to follow-up on injury status. In case the participants recovered from injury, questions regarding the use of medication (yes/no), treatment assistance from health professional (yes/no), surgical treatment (yes/no) and missed days from work (number) were asked. In addition, participants had to report their motivation to start running again after having had an injury and this information was then dichotomized into: 1) Less motivated or not at all motivated or 2) motivated or very motivated. If a participant completely recovered from injury and sustained an additional running-related injury afterwards, the participant had to attend a clinical examination again. The possibility of clinical examinations was stopped after the participants had been included in the DANO-RUN study for 1-year. The follow-up on injured participants were stopped February 2013, eighteen months after the first participants were enrolled at a baseline investigation and 7 months after the last participants completed follow-up.
Descriptive data were presented as counts and percentage dichotomous or categorical data. Data on time to recovery were presented as medians and the range between minimum and maximum because data on injury were considered non-parametric evaluated by histograms and quartile-quartile plots. Contra wise, data on the log scale was normally distributed. Therefore, the student's t-test was used to test if time to recovery (days) was different between those motivated to take up running again after having had an injury compared with those being less motivated. The Wilcoxon rank sum test was used to test if the time to recovery was different across gender and across age (dichotomized into less than or above 40 years because masters runners typically are defined as persons above 40 and face subtle differences in injury rate and location[10] (link)) because the data were not normally distributed on original scale or on the log scale. All analyses were performed using STATA/SE version 12.1. A result was considered significant at p<0.05.
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