Research Article Musculoskeletal Injuries and Training Patterns in Junior Elite Orienteering Athletes

Hindawi Publishing Corporation BioMed Research International Volume 2015, Article ID 259531, 8 pages http://dx.doi.org/10.1155/2015/259531 Research Article Musculoskeletal Injuries and Training Patterns in Junior Elite Orienteering Athletes Lilian Roos,1,2 Wolfgang Taube,2 Peter Zuest,3 German Clénin,3 and Thomas Wyss1 1 Swiss Federal Institute of Sport Magglingen (SFISM), 2532 Magglingen, Switzerland 2Department of Medicine, Movement and Sport Science, University of Fribourg, 1700 Fribourg, Switzerland 3Swiss Orienteering Federation, 4600 Olten, Switzerland Correspondence should be addressed to Lilian Roos; [email protected] Received 29 May 2015; Accepted 1 July 2015 Academic Editor: Peter Krustrup Copyright © 2015 Lilian Roos et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Findings about the relation between musculoskeletal injuries and training patterns in orienteering athletes are sparse. Therefore, the musculoskeletal injuries and training patterns of 31 Swiss elite orienteering athletes aged 18-19 years were analyzed in a retrospective study. Individual training diaries and medical records were used to assess training data and injury history, respectively. Group comparisons and a multiple linear regression (MLR) were performed for statistical analysis. The junior elite orienteering athletes performed 7.38 ± 2.00 training sessions weekly, with a total duration of 455.75 ± 98.22 minutes. An injury incidence rate (IIR) of 2.18 ± 2.13 injuries per 1000 hours of training was observed. The lower extremity was affected in 93% of all injuries, and the knee (33%) was the most commonly injured location. The MLR revealed that gender and six training variables explained 60% of the variance in the injury severity index in this study. Supported by the low IIR in the observed age group, the training protocol of the junior elite orienteering athletes was generally adequate. In comparison to elite track, marathon, and orienteering athletes, the junior elite athletes performed less high-intensity interval training (HIIT). However, more frequent HIIT seems to be a protective factor against injuries. 1. Introduction limiting the preparation time for the competition season [12]. Characteristics of musculoskeletal injuries in running- Monitoring training is indispensable for competitive athletes relatedsportshavebeenwidelyinvestigatedandvarying whoaspiretoexcelatelitelevels.Basedonasystematic injury incidence rates (IIRs) per 1000 hours of training have collection of training data, planned and performed training been reported. In van Mechelen’s review [13], 2.5–12.1 injuries content and intensity can be compared [1, 2]. Further, per 1000 hours of running were reported for recreational and monitoring training supports holistic training regulations competing runners. Other authors have reported a similar and is, therefore, important to enable optimal individual range of IIRs between 1.7 and 10.0 injuries per 1000 hours of training adaptations [3]; hence, prevention or early detection running exposure [14, 15]. In a recent review, an IIR range of musculoskeletal injuries might be possible [4]. Since of 2.5–38.0 was reported [16]. Comparisons between studies musculoskeletal injuries are a major reason for premature that assess IIR must be made with caution due to the different career termination in elite athletes [5–7], every effort to use definitions of running-related injuries, the subjects included, training monitoring data for injury prevention is paramount. andthemethodsusedforinjuryassessment[9]. Competitive Musculoskeletal injuries are generally defined as injuries and elite athletes tend to have fewer IIRs per 1000 hours of or disorders of the muscle, tendon, bone, joint, ligament, exposure than recreational or inexperienced athletes [13, 15]. or nerves [8, 9]. Injuries can be defined further by the In a study with young competitive orienteering athletes, 3.0 location, type, grade of injury, or training days lost due to injuries per 1000 hours of training were reported [12]. an injury [10–12]. Injuries not only pose a problem to the Orienteering is a running-related endurance sport physiological system but can also be a psychological burden, comprised of physical and cognitive components. 2 BioMed Research International Orienteering athletes compete on a timed run through 2.2. Training Diary and Medical History. The athletes pro- unknown cross-country terrain, checking in at vided their training diaries in digital or paper-pencil versions predetermined control sites while navigating with only as far retrograde as available. Every training session recorded amapandcompass[17, 18]. The most common events are in a paper-pencil training diary was digitized. Afterwards, sprint and middle and long distance races, with completion the variables were summarized for each training week. With times of 15–20, 40–50, and 70–90 minutes, respectively. the weekly data, the individual annual mean was calculated Different competition modes exist; however, most often the per age group. The variables were total duration, duration, athletes start individually within short time intervals [11, 19]. total frequency, and frequency for endurance running, HIIT, Switzerland has a history of successful orienteering athletes. orienteering, strength training, complementary endurance The final ranking of the 2014 International Orienteering training, and regeneration, with warm-up and cool-down Federation World Cup [19]displayedSwitzerlandasthebest and stretching subcategories included in the duration vari- nation, with 5 women classified in the top 12 and 7 men in able, training load, monotony in total duration, monotony the top 15. Due to the impressive international success of in training load, and proportion of HIIT within endurance Swiss orienteering athletes, an investigation of their injury running (Table 1). Training load was computed according to and training data is of great interest. Foster et al. [24]andEdwards[25]. A factor was assigned to Recently, training data of Norwegian elite orienteering each training intensity category (regenerative = 1; extensive athletes were published. Tønnessen et al. [20]reportedthe =2;moderate=3;intensive=4;supramaximal=5).To annual training periodization of eight Norwegian world calculate the training load, training duration in each intensity champions in orienteering. During their most successful category was multiplied with the corresponding factor and seasons, leading to a win at the World Orienteering Cham- summarized. Monotony in weekly training duration was pionship, the athletes recorded 9-10 training sessions and computed as “mean duration per week” divided by the 10.6–14.9 hours of training duration per week. A significant “standard deviation duration per week.” Similarly, monotony reduction in training duration from general preparation to in training load was computed as “mean training load per specific preparation and competition phase was observed. week” divided by the “standard deviation training load per This was primarily due to a reduction of training sessions week” [26]. The proportion of the HIIT within all endurance of low-to-moderate intensities, whereas the high-intensity running training sessions was computed as “duration of interval training (HIIT) duration was increased [20]. An HIIT” divided by the “sum of the duration of HIIT and older study with female elite orienteers reported 3–7 training endurance running.” sessions per week, with 63% of squad members training Injuries and illnesses were assessed from the athletes’ between 5.0 and 8.9 hours per week [11]. More research is personal medical records. The medical doctors of the Swiss availableforelitetrackandmarathonrunners,reportedto Orienteering Federation maintained these records. All entries train 10–13 training sessions per week and running an average concerning disorders of the musculoskeletal system, con- of 126–186 km per week [21, 22]. cussions, or illnesses to other body systems were included. Little is known about the relation between such training Illnesses were classified using the International Classification data and injury occurrence in the running-related sport of of Primary Care, Second Edition (ICPC-2) [27]. For injury orienteering. Therefore, the aim of this study was to inves- classification, the Orchard Sports Injury Classification System tigate the relationship between the data from the athletes’ version 10 (OSICS-10) was used [28]. The first letter of training diaries recorded at the ages of 18 and 19 years and the code determined the location of the injury and the injury occurrence in Swiss junior elite orienteering athletes. second letter defined the type of injury. Further, injuries were discriminated into acute and overuse injuries. Acute 2. Materials and Methods injuries were caused by a sudden single traumatic event, whereas overuse injuries originated from repetitive overload 2.1.StudyDesignandSelectionofParticipants.Aretro- of the same musculoskeletal structures without a clearly iden- spective study design was chosen in cooperation with the tifiableevent.Eachinjury’sseveritywasclassifiedastrivial Swiss Orienteering Federation, which has been monitoring (no consequences), minimal (1–3 training days lost, TDL), the injuries, illnesses, and performance changes of their mild (4–7 TDL), moderate (8–28 TDL), severe (>28 TDL), or elite athletes

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