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

Damsted et al. Injury Epidemiology 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 Camma Damsted 0 Erik Thorlund Parner 2 Henrik Sørensen 0 Laurent Malisoux 1 Rasmus Oestergaard Nielsen 0 0 Section of Sport Science, Department of Public Health, Aarhus University , Dalgas Avenue 4, 8000 Aarhus C, DK , Denmark 1 Sports Medicine Research Laboratory, Department of Population Health, Luxembourg Institute of Health , L-1460 Luxembourg , Luxembourg 2 Section of Biostatistics, Department of Public Health, Aarhus University , 8000 Aarhus, DK , Denmark 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 halfmarathoners 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 halfmarathon 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. Half-marathon; Running schedule; Running-related injury; Load capacity; Training load Background After more than two decades with a steadily increase in the engagement into running (Billat, 2005; Pilgaard & Rask, 2016) the popularity of running now ranks in the top of the most popular physical activities (Pilgaard & Rask, 2016; Cave & Miller, 2016) . Further, thanks to its high practical feasibility, running has reached out broadly in a multitude of countries (Billat, 2005; Cave & Miller, 2016; Buist et al., 2010) . Historically, the five and 10 km running distances have been the main standard distances, demonstrated by a continually high number of runners participating in race events on these distances (DAF & MotionDANMARK, 2014). Currently, a tendency towards an inversion of this picture seems to be ongoing, with a growing interest towards longer distances such as half-marathon and marathon. Since 2000, a particular attractiveness of running a half-marathon has been steeply increasing (DAF & MotionDANMARK, 2014; Running USA, 2014) , showed by a 307% growth in United States half-marathon finishers (from 482,000 in 2000 to 1,960,000 in 2014). In parallel, an increasing number of official half-marathon racing events have been organized (Running USA, 2014) . This popularization of half-marathon is also reflected by the surface of a vast number of free half-marathon running schedules that now are available in sports magazines and on the Internet. Similarly to other forms of physical activity, training for half-marathon has advantageous impacts on healthrelated factors, including reduced all-cause mortality (Evenson et al., 2016; Lee et al., 2014) , increased quality of life (Pedersen & Saltin, 2015) , and reduced risk of many chronic- and lifestyle diseases (Pedersen & Saltin, 2015) . Furthermore, through its high positive influence on the cardiovascular and respiratory systems (Warburton et al., 2004) it has direct effects on variables lik (...truncated)