In an athlete's life, uncontrolled pain can have a negative effects as it may be source of further and more serious injuries as well as a trigger for -or a consequence of- psychosocial problems and illnesses (Putukian, 2016). Sports students are a special group of athletes, with diverse demands. There are multiple interactions between pain and students' biopsychosocial health (Bailer et al., 2008), an increased stress level due to the double burden of theoretical requirements and performance pressure. In consequence, an impairment of students' mental and physical health is likely (Putukian, 2016).
Injuries seem to be a key stress factor for sport students (Putukian, 2016), which are more often affected by injuries than other student groups (Dreiskamper et al., 2015). Most recent studies on the psychosocial state of German students point to a concerning development of mental symptoms and fear of failure among the students (Beiter et al., 2015). Studies show that higher resilience and increased resources of athletes, e.g. self-compassion, lead to a better ability to cope with pain and injury (Reis et al., 2015). Beyond that, mental resources, skills for pain management, and coping strategies can affect the healing process of an injury (Kleinert, 2001).
However, little is known about the prevalence of pain in sports students. So far there are only a few studies dealing with this topic, and there is a need for a systematic assessment of biopsychosocial factors in athletes and sports students based on the recommendations of the International Association for the Study of Pain (IASP) for pain assessment and management of pain (IASP, 2018).
The aim of the present survey was to evaluate the prevalence of existing pain and injuries, to obtain a more differentiated understanding of coping with pain and stress in sports, and also to pay adequate attention to mental health and quality of life for sports students.
We conducted an exploratory cross-sectional electronic survey based on the German Pain Questionnaire, and adapted to sports students' needs, taking into account demographic particularities of sports students. The study was approved by the Ethics Committee of the Goethe University of Frankfurt am Main (reference number 2017-22), and is in accordance with the Declaration of Helsinki (Version Fortaleza 2013).
Potential participants were all current students at faculties of sports sciences in Germany, Austria, and Switzerland (DACH region), as well as in Luxemburg and Liechtenstein. Faculties were retrieved by online research and according to the list of the German Society of Sport Science (DVS, 2016). All faculties (deans, course directors, student associations) were contacted by mail (in total 321 inquiries) and by announcement in social networks. According to country size and population, the number of contacted universities was highest in Germany (62) and less in Switzerland (21) and Austria (5). Interested candidates could participate online if they met the following inclusion criteria: Participants had to confirm to be a registered student in a sports science course or in a teacher training with the subject of sport at higher education institutions, universities, and colleges. Prior to participation, all candidates provided online consent.
Experimental design and outcome assessment
From June to November 2017, the survey was publicly accessible via web-based academic survey system (SoSci Survey GmbH, Munich, Germany) to get a period prevalence. To address the different dimensions of pain, we developed the German Sports Pain Questionnaire (see supplementary data 2), which is a modified version of the German Pain Questionnaire (Nagel et al., 2012) including own questions, not validated yet, of demographic and anthropometric data, sports activity, history of past and present injury and medication, as well as seven validated questionnaires (all in German versions): The Regional Pain Scale (RPS) to determine the localisation of pain (Hauser et al., 2010); The 12-item Short Form Health Survey (SF-12) for physical and mental quality of life; The NRS pain scale to specify the localisation and sensation of pain (10-scaled Numerical Rating Scale NRS, with 0 = no pain and 10 = maximum pain); The Quality of Life Impairment by Pain Inventory (QLIP), showing the intra-individual development of the patient's impairments (Nagel et al., 2012); Two questions of the Patient Health Questionnaire (PHQ) to monitor the quality of sleep (Grafe et al., 2004); The Depression, Anxiety and Stress Scales (DASS; Depression cut off 10, anxiety cut off 6, stress cut off 10, (Nilges and Essau, 2015)). In addition we assessed the Self-Compassion Scale Short Form (German Version; SCS-D SF) addressing the physical and mental health state (Hupfeld and Ruffieux, 2011). The sequence of all single questionnaires was in a standardised order: RPS, SF-12, NRS, QLIP, DASS, SCS-D SF. All participants could enter free comments concerning their experiences with pain and sports before submitting the survey that will be qualitatively analysed coping strategies for pain and injuries.
The NRS was also used to split the sample according to the World Health Organisation (WHO) and the standard criteria of expert standard Pain Management in care into two subgroups perceiving current pain lower or higher than "3" on the NRS (Schmidt, 2016). In addition, data was analysed for chronic pain, abuse of drugs and alcohol, training loads, and sex differences.
To allow interpretations, all results were compared to age-controlled reference and norm data (see Table 1).
Statistical data processing was performed using SPSS (Version 24; IBM Deutschland GmbH, Ehningen). Since all data had a normal distribution (Kolmogoroff-Smirnoff-Lilliefors test), data are expressed as means and standard deviations (95%-CI). For statistical analysis between different subgroups, the T-test for independent samples and the [Chi.sup.2] test for categorised data were applied. The level of statistical significance was set at p
Free comments were classified into categories, as follows: (i) Performing sports despite pain and injury, (ii) Physiological contexts, (iii) Pain tolerance and pain sensitivity, (iv) Decision-making process concerning injury break, (v) Personal statements and coping strategies, (vi) Conditions for sports studies and (vii) Comments on positive effects of sport. Twenty-nine comments were considered being non-substantial in regard to pain and injury, or contained personal communications as well as positive feedback, and are not reported in this file.
In total, about 2,500 clicks on the website have been recorded, while 865 sports students (23.35 [+ or -] 2.98 years; BMI 22.49 [+ or -] 2.41; 526 female, 339 male) gave consent to participate. 664 participants (78%) completed the full survey, 768 students finished at least the main part of pain-related questions. Most of the students were registered at German universities (88%). 12.8 % of the participants studied at Swiss and Austrian universities. The majority planned to graduate as a teacher (state exam 52%) or while receiving a Bachelor degree (44%). The mean progress in terms (2 terms/year) was 5.18 [+ or -] 3.02.
The scores of the different pain items are summarised in Table 1. The RPS reported an average of 3.84 [+ or -] 2.98 (rating scala "0" no region of pain to "19" pain in all sites mentioned) sites of current, acute pain or tenderness, with a focus on: Neck (48 %), lower back (45 %), right (38 %) and left (26 %) shoulder, right (24 %) and left thigh (21 %), and knees (21 %; see Table 2). The mean value of the mental component score (MCS-12) was 47.64 [+ or -] 9.51 (range: 0-100; 100 = very good health), of the physical component score (PCS-12) 48.88 [+ or -] 6.59 (range: 0-100; 100 = very good health). The average current pain intensity was 1.83 [+ or -] 1.93 NRS (rating scala "0" no pain to "10" worst pain imaginable), while 91 students (13%) reported ongoing pain (polar question: yes or no). The pain-induced limitations of global quality of life (QLIP) scored 31.98 [+ or -] 6.54 (43 = excellent quality of life). The results of the DASS were as follows: Depression 3.20 [+ or -] 3.55, anxiety 1.87 [+ or -] 2.45, stress 3.79 [+ or -] 3.67 (0 = little risk for each sub-cale). Self-compassion was rated 38.40 [+ or -] 7.35 (60 = excel lent self-compassion)). Figure 1A shows an extrapolated spider diagram of all pain-related scores.
Workload, injuries and pain
93% of sports students reported performing sports regularly, and only 2.0 % stated being inactive. The focus of the main training load was in the students' recreational sports: 29.5 % are five to seven hours active per week, 26.1 % three to five hours per week, while 17.7 % are practicing sports even for nine to twelve hours per week. Nevertheless, looking at the training load in preparation for practical tests at university, 25.8 % stated one to three hours per week, 18.2 % five to seven hours, 10.3 % five to seven hours while 34.3 % reported not preparing actively for university tests. Neither training load nor adherence to a youth league revealed significant differences between scores (p > 0.05). Most rated disciplines in recreational sports were weight training and fitness (21.07 %), running (16.71 %), ball games (18.52 %) water sports (11.02 %) and mountain sports (10.29 %). Being in a club or practicing on a competitive level was found mostly for these disciplines: Soccer (23.88 %), handball (13.06 %), beach-/volleyball (8.77 %), gymnastics (8.58 %) and water sports (5.41 %). Still, 69% of the students had one or more practical sports courses. Within the previous eight weeks, almost three of four students suffered an accident or injury (of any kind), received a medical diagnosis related to pain, or perceived...