Frequency of Injury and Illness in the Final 4 Weeks before a Trail Running Competition

) determine self-reported injury and illness frequency in trail runners 4 weeks preceding competition; (ii) compare athletes with and without injury/illness by sex, age, body mass index (BMI) and competition distance; (iii) describe mechanism of injury, anatomical region (injury)/organ system (illness) involved, consequences of injury on preparation and self- perception of injury severity; (iv) compare anatomical region (injury) and

to (i) determine self-reported injury and illness frequency in trail runners 4 weeks preceding competition; (ii) compare athletes with and without injury/illness by sex, age, body mass index (BMI) and competition distance; (iii) describe mechanism of injury, anatomical region (injury)/organ system (illness) involved, consequences of injury on preparation and self- perception of injury severity; (iv) compare anatomical region (injury) and organ system (illness) by sex. A total of 654 trail runners (age 36.2, IQR 30.6–43.0; 36.9% females) participated in this retrospective cross-sectional study by completing a self-reported questionnaire. Injury and illness frequency rates were 31.3% (n= 205, CI: 27.7–35.0%) and 22.3% (n= 146, CI: 19.1–25.7%), respectively. No signi cant difference was found between injured vs. non-injured or ill vs. non-ill study participants by sex, age, BMI and competition distance. Regarding injuries, gradual onset (41.6%) and knee (33.2%) were the most indicated mechanism and anatomical region of injury. At least 85.4% of trail runners changed their training following injury and 79% indicated that their injury would affect their competition performance. Regarding illness, the respiratory tract was the most frequent organ system involved (82.9%). Male and female participants reported similar proportions of anatomical regions (injury) and organ systems (illness) affected. These results could help to generate education strategies and appropriate medical support before and during these competitions. Keywords:athletic injuries; musculoskeletal injuries; disease; injury management; trail running 1. Introduction Running is one of the most popular forms of physical activity because of its accessibil- ity and low cost required for participation. Positive lifestyle changes including physical, psychological and social bene ts are attributed to running [1]. Trail running is one of the running disciplines that has grown worldwide over the last years [2]. According to the International Trail Running Association, trail running is a pedestrian race, in a natural environment (e.g., mountain, forest, prairie) containing a minimal of asphalted or paved routes (under 20% of the total route) and which ideally, though not necessarily should be Int. J. Environ. Res. Public Health2021,18, 5431.

a pedestrian race, in a natural environment (e.g., mountain, forest, prairie) containing a minimal of asphalted or paved routes (under 20% of the total route) and which ideally, though not necessarily should be Int. J. Environ. Res. Public Health2021,18, 5431.

Int. J. Environ. Res. Public Health2021,18, 5431 2 of 10 self-suf cient (i.e., the runner must be autonomous between helping or supplying stations regarding clothing, communication, food and drinks) [3]. Despite all the health bene ts associated with physical activity, the risk of medical encounters such as injuries and illness is relatively high. The incidence of running-related injuries in disciplines covering from track and eld athletes to marathon runners ranges from 19.4 to 79.3% [4] over twelve weeks to one year of follow-up. Kluitenberg et al. [5] described the prevalence of injuries in different populations of runners depending on their experience and type of competition, reporting a prevalence of 16.7 to 84.9% in novices, 21.6 to 55.0% in recreational runners, 1.4 to 94.4% in cross country runners and 21.0 to 90.6% in ultra-distance runners [5]. A recently published systematic review [6] showed an overall incidence range between 1.6–4285.0 injuries per 1000 h of running. Additionally, the prevalence of injuries in trail runners has been reported between 22.2% [7] during competition and 28.2% [8] over one year with the lower limbs the most susceptible to sustain injuries. Illnesses are also prevalent among athletes. Viljoen et al. [6] showed an overall incidence range between 65.0–6676.6 illnesses per 1000 h of running and the digestive system was the most common trail running illness reported. Moreover, upper respiratory illness that interfere with training and performance during competition has been reported in up to 10% of athletes [9]. Other systems commonly affected by illness are skin and subcutaneous tissues and the genitourinary system [10]. These injuries and illnesses have important consequences for the athletes' health, such as early-onset osteoarthritis in the long term, rising health costs [11], absenteeism from work, loss in training days, diminished performance in the short term and, in some cases, dropping out of sport participation [12] and a negative impact on performance [9]. Injuries related to trail running are multifactorial and generally described as gradual onset injuries (repetitive micro-trauma) and sudden onset injuries (muscle strain, ligament sprains, etc.) [13]. Bertelsen et al. [14] present an evidence-informed conceptual framework outlining the multifactorial

performance in the short term and, in some cases, dropping out of sport participation [12] and a negative impact on performance [9]. Injuries related to trail running are multifactorial and generally described as gradual onset injuries (repetitive micro-trauma) and sudden onset injuries (muscle strain, ligament sprains, etc.) [13]. Bertelsen et al. [14] present an evidence-informed conceptual framework outlining the multifactorial nature of running-related injury etiology. This framework hypothesizes that a running-related injury occurs when accumulated loads per running session exceed the structure-speci c load capacity when entering a running session. The structure-speci c load capacity when entering a running session can adapt positively or negatively over time. This ability to adapt can be in uenced by factors such as sex, age, or running distance. Loads associated with running could be quanti ed by the number of steps and the magnitude of the load in each step, so variables such as running distance, weight and BMI are also relevant to analyze. Some factors commonly associated with running injuries are the history of previous injuries and training programs with excessive overload [15]. Training load changes during the pre-competitive phase of an athlete's training plan. The volume and intensity of training increase and then progressively decrease before the competition, a phenomenon known as tapering [16]. This increase in training load could affect the athlete's stress levels, exposing them to a greater injury risk [17] and increases the risk of illness due to alterations to the immune system [9]. Athletes are particularly vulnerable during the season of major competitions when they continue their training despite having an injury or illness [15,18,19]. A four-step strategy for injury prevention has been proposed by van Mechelen et al. [20]: (i) to know the extent of the problem; (ii) to know the risk factors and in- jury mechanisms; (iii) to introduce a preventive measure; and (iv) to assess the effectiveness of this preventive measure. From the perspective of knowing the extent of the problem, studying the prevalence of injuries around a competition phase may be important to un- derstand the magnitude of the problem [11,15,18,19,21], with the ultimate

(ii) to know the risk factors and in- jury mechanisms; (iii) to introduce a preventive measure; and (iv) to assess the effectiveness of this preventive measure. From the perspective of knowing the extent of the problem, studying the prevalence of injuries around a competition phase may be important to un- derstand the magnitude of the problem [11,15,18,19,21], with the ultimate goal to generate education strategies and provide better medical support during competitions. Only a few studies have determined the frequency or prevalence of injuries or illnesses in trail runners [8,11,13,22,23] and no available studies have focused on the speci c stage before the competition. This study aimed to (i) determine the self-reported frequency of injuries and illnesses in athletes participating in a trail running competition over the four weeks preceding the competition; (ii) compare athletes with and without injury/illness by sex,

Int. J. Environ. Res. Public Health2021,18, 5431 3 of 10 age, body mass index (BMI) and competition distance; (iii) describe the mechanism of injury, the anatomical region (injury) or organ system (illness), consequences of injury on training features (i.e., volume, intensity and performance) and self-perception of the severity of injury for competition; and (iv) compare the anatomical region among injured athletes and the system affected among ill athletes by sex. 2. Materials and Methods 2.1. Study Design and Setting The study used a retrospective cross-sectional design. A total number of 1185 athletes entered the trail running event that occurred on 24 and 25 June 2017. The competition distances included continuous race distances over 11, 18, 24, 45 and 63 km and a two-phase distance Traves½a Crossing of 23 km and 22 km over two days. During the reception of the competition kit one day before the event, all athletes were personally invited to participate. 2.2. Participants Competition entrants 18 years and older that registered for the event and signed a participation informed consent were included in the study. All information was treated as strictly con dential and the injury and illness reports were anonymously recorded according to the guidelines of the Declaration of Helsinki. This research was assessed and approved by the Ethics Committee of the Medicine Faculty of Austral University of Chile (3003.2017) and followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Guidelines. 2.3. Data Sources and Variables A self-reported questionnaire in hard copy was completed the day before the competi- tion by all participants who agreed to participate in the study, regardless of if they competed or not. They were assisted by physiotherapists previously trained in the completion of the questionnaire. The questionnaire was based on preceding surveys used by the International Association of Athletics Federations and the F²d²ration Internationale de Natation during the World Championships in 2013 [15,19]. We used a forward translation and backward veri cation method to translate the English version into Spanish, adjusting the questions to trail runners. This process involved the translation of the questionnaire by a bilingual translator with

on preceding surveys used by the International Association of Athletics Federations and the F²d²ration Internationale de Natation during the World Championships in 2013 [15,19]. We used a forward translation and backward veri cation method to translate the English version into Spanish, adjusting the questions to trail runners. This process involved the translation of the questionnaire by a bilingual translator with a Spanish mother tongue, followed by the veri cation of the translated version by a bilingual person with an English mother tongue [24]. The questionnaire was divided into two sections. In the rst section, questions covered sociodemographic data (age, sex, height and weight), distance of competition, weekly training hours in the last 4 weeks and questions to determine health status (injuries and illnesses in the last 4 weeks). Injury was de ned as “injuries or physical complaints (such as pain, ache, stiff- ness, swelling, instability/giving way, locking or other symptoms) that athletes had in the four weeks prior to the championship, even if this had no major consequences for the athlete's participation in normal training and/or competition” [25]. Illnesses were de ned as “any symptoms implying infection, allergy, gastroenteritis, u, or dehydration that affected the competition preparation”. If the athletes did not report any injuries or illnesses in the 4 week period before the competition, the questionnaire was ended. The second section (if athletes reported an injury or illness) was composed of questions about injury mechanism, anatomical regions of injury, self-perceived impact of injury on training preparation for the event (i.e., volume, intensity and performance), self-perceived impact of injury on the competition (i.e., severity) and organ system affected by illness. 2.4. Statistical Methods The Shapiro–Wilk test was used to analyze whether quantitative variables had a normal distribution. Since this assumption was not reached by any variable, median and interquartile range (IQR) were reported. A 95% con dence interval (CI) was used in the frequency analyses. Missing data were ignored (complete case method) and we reported

was not reached by any variable, median and interquartile range (IQR) were reported. A 95% con dence interval (CI) was used in the frequency analyses. Missing data were ignored (complete case method) and we reported

Int. J. Environ. Res. Public Health2021,18, 5431 4 of 10 the extent of missing data. In order to assess the external validity of our ndings, the study participants and registered athletes in the event were compared using chi-square (sex and competition distance) and Mann–Whitney U tests (age). For aim 1, descriptive statistics were used to describe the frequency of injury and illness among athletes. For aim 2, injured and non-injured athletes and ill and non-ill athletes were compared by age and BMI using the Mann–Whitney test and by sex and competition distance using the chi-square test. For aim 3, descriptive statistics were used. For aim 4, anatomical regions and organ systems were compared within injured/ill athletes by sex (males/females) using the chi/square test. Data were analyzed using STATA 14 software. 3. Results Of the 1185 registered entrants, 654 (55.2%) runners, 241 (36.9%) females and 413 (63.1%) males accepted to participate and completed the questionnaire. There were no signi cant differences between the group of participants and total competition entrants regarding sex (p= 0.546), age (p= 0.508) and competition distance (p= 0.100). 3.1. Aim 1: Frequency of Injury and Illness Regarding injuries, 31.3% (n= 205, CI: 27.7–35.0%) of participants indicated they had an injury in the 4 weeks prior to the competition. Of those who reported injuries, 62 (30.2%) reported having more than one injury during the previous 4 weeks. Illness during the 4 weeks before competition was reported by 22.3% of participants (n= 146, CI: 19.1–25.7%). The frequency of injuries and illnesses in the 4 weeks before the event is shown in Table. Table 1.Demographic and race distance characteristics of participants. Totaln= 654 Injured Athletes n= 205 Non-Injured Athletes n= 449 p-Value Ill Athletes n= 146 Non-Ill Athletes n= 508 p-Value Sex ‡ Female 241 (36.9) 74 (30.7) 167 (69.3) 0.787 59 (40.4) 182 (35.8) 0.312 Males 413 (63.1) 131 (31.7) 282 (68.3) 87 (59.6) 326 (64.2) Age (years) † 36.2 [30.6–43.0] 36.7 [30.4–43.9] 35.9 [30.8–42.3] 0.595 36.4 [30.5–41.2] 36.1 [30.7–43.3] 0.632 Height (cm) †,§ 170.0 [163.0–175.0] 170.0 [163.0–175.0] 170.0 [163.0–175.3] 169.5 [162.3–176.0] 170.0 [164.0–175.0] Weight (kg) †,§§ 70.0 [60.0–78.0]

p-Value Sex ‡ Female 241 (36.9) 74 (30.7) 167 (69.3) 0.787 59 (40.4) 182 (35.8) 0.312 Males 413 (63.1) 131 (31.7) 282 (68.3) 87 (59.6) 326 (64.2) Age (years) † 36.2 [30.6–43.0] 36.7 [30.4–43.9] 35.9 [30.8–42.3] 0.595 36.4 [30.5–41.2] 36.1 [30.7–43.3] 0.632 Height (cm) †,§ 170.0 [163.0–175.0] 170.0 [163.0–175.0] 170.0 [163.0–175.3] 169.5 [162.3–176.0] 170.0 [164.0–175.0] Weight (kg) †,§§ 70.0 [60.0–78.0] 70.0 [60.0–77.8] 70.0 [60.0–79.0] 70.0 [60.0–80.0] 70.0 [60.0–78.0] BMI †,§§§ 24.0 [22.2–26.0] 24.1 [22.3–25.8] 23.9 [22.2–26.1] 0.996 24.2 [22.6–26.1] 23.9 [22.2–25.9] 0.343 Distance ‡ 11 k 194 (29.7) 64 (33.0) 130 (67.0) 0.411 49 (33.6) 145 (28.5) 0.817 18 k 136 (20.8) 36 (26.5) 100 (73.5) 27 (18.5) 109 (21.5) 24 k 144 (22.0) 44 (30.6) 100 (69.4) 29 (19.9) 115 (22.6) 45 k 101 (15.4) 36 (35.6) 65 (64.4) 24 (16.4) 77 (15.2) 63 k 47 (7.2) 18 (38.3) 29 (61.7) 11 (7.5) 36 (7.1) Crossing (23 + 22 k) 32 (4.9) 7 (21.9) 25 (78.1) 6 (4.1) 26 (5.1) Note:n, number; cm, centimeters; kg, kilograms; BMI, body mass index; k, kilometers. † Median, Interquartile range [IQR]; ‡ absolute frequency, percentage (%); § missing data for 19 participants (5 females and 14 males; 4 injured and 15 non-injured athletes); §§ missing data for 19 participants (4 females and 15 males; 3 injured and 16 non-injured athletes); §§§ missing data for 22 participants (6 females and 16 males; 5 injured and 17 non-injured athletes). 3.2. Aim 2: Comparison of Injured and Ill Athletes by Sex, Age, BMI and Competition Distance There was no statistically signi cant difference between injured vs. non-injured or ill vs. non-ill athletes by sex, age, BMI, or competition distance (Table). 3.3. Aim 3: Description of the Mechanism of Injury, Anatomical Region (Injury) or Organ System (Illness), Consequences of Injury on Training (i.e., Volume, Intensity and Performance) and Self-Perception of the Severity of Injury for Competition Of the 205 athletes reporting an injury, most athletes (41.6%;n= 84) indicated that the injury had gradual onset, 26.7% (n= 54) reported sudden onset without trauma, 20.8% (n= 42) reported an identi able event such as a fall while running and

Consequences of Injury on Training (i.e., Volume, Intensity and Performance) and Self-Perception of the Severity of Injury for Competition Of the 205 athletes reporting an injury, most athletes (41.6%;n= 84) indicated that the injury had gradual onset, 26.7% (n= 54) reported sudden onset without trauma, 20.8% (n= 42) reported an identi able event such as a fall while running and 10.9% (n= 22) an incident unrelated to running. Nine participants (4 females and 5 males, 4.4%) did not report the injured anatomical region. The knee was the most affected site (33.2%) for both sexes, followed by the hips in females (14.3%) and the ankle in males (16.7%) (Figure). From the reported illnesses

This study investigates injury and illness prevalence among trail runners before competition.