A cross-sectional study was designed, involving Spanish male and female elite track and field athletes. The STROBE and CHERRIES guidelines were taken into account for this study (Additional files 1 and 2, respectively). The study was conducted according to the Code of Ethics of the World Medical Association (Declaration of Helsinki). The ethical committee of the Universidad Camilo José Cela (Spain) approved this study.
During the 2019 outdoor season, all national elite track and field athletes were invited to voluntarily and anonymously participate in this study by the national track and field federation through email. Participants were asked to complete an anonymous online questionnaire through the Survey Monkey® platform (CA, USA). The sample size was calculated as a proportion of finite population, considering a 99% confidence level to estimate an expected prevalence of 50% in the total population, for 5% accuracy in the study. At the time of the study, the National Sports Council certified 711 elite track and field athletes, so the estimated minimum sample size was 345 elite track and field athletes. Following the Spanish Royal Decree 971/2007, elite athletes were defined as those who had a valid certificate of being “high-level athlete” and/or “high-performance athlete.” As inclusion criteria, we considered elite athletes aged 14 years or older, who practice any of the track and field events. We excluded athletes who were pregnant when the study started or in the past year or did not have the ability to adequately understand instructions in Spanish as the national language. Prior to completing the questionnaire, all participants gave their consent to participate after having been informed of the purpose of the study, instructions, and expected time for completing the survey. They were also informed about the research team, location where responses would be stored, time during what data would be stored and data protection (anonymity) issues. Survey data were automatically processed by the platform and stored on an external device with a password-protected server. All information was always in the custody of the research team members, in line with new continental data protection and national norms. Incentives were not offered for participating in the study.
Although patients and members of the public were not involved in the design, management, or conduct of the research, once it has been published, participants will be informed of the results through a dedicated website and will be sent details of the results in a study newsletter suitable for a non-specialist audience.
The open online questionnaire was designed to be anonymous, and before being spread, usability and proper performance was verified. It was made up of adaptive items, which means that some items were conditionally displayed based on responses to previous items. Thus, total number of pages was variable based on the participants’ responses. To avoid dropouts, the number of items per page ranged from 2 to 6, as maximum. Before the final submission, participants were always able to review and change their responses through a back button. Uncompleted questionnaires were removed from the analysis. It contains four main sections to collect the following information: (a) socio-demographic and anthropometric data: age, sex, weight and height; (b) medical history: common diseases, constipation, urinary infection (urinary tract infection, diagnosed with laboratory tests), gynecological data and problems (i.e., polycystic ovarian syndrome, fibroids, endometriosis, or pelvic inflammatory disease; gynecological disorders related to menstrual disorders, vaginal infections, sexually transmitted diseases, or dyspareunia were analyzed independently), or prostatic problems (i.e., benign prostatic hyperplasia, prostatitis, prostate surgery, or prostate cancer); (c) training characteristics: track and field event specialization (i.e., the main event for which athletes train and compete during the season), years of experience, training volume (hours/day, days/week, weeks/years), and resting (hours between training sessions, weeks/year); (d) UI data: type, severity, and social impact according to International Urogynecological Association and International Continence Society recommendations, as assessed through the following validated questionnaires:
International Consultation on Incontinence Questionnaire-UI Short-Form (ICIQ-UI-SF) (Spanish version)
This questionnaire is a self-administered tool to determine if a subject has UI and, if so, its frequency, severity (according to the amount of urine leakage), and whether there are impacts on quality of life (QoL). It consists of 3 items that evaluate these three aspects, respectively. The occurrence of UI is established according to the response to items 3, 4, or 5; when the sum of values from these questions is ≥ 1, UI is considered to be present. The total score is the result of the sum of these 3 items, ranging from 0 to 21 points. Apart from these 3 items, the questionnaire contains 8 additional questions related to the type of UI; these questions are not part of the questionnaire score, but have a descriptive and guiding purpose for assessing the UI type .
Three Incontinence Questions Questionnaire (3IQ) (Spanish version)
Three questions are used to define whether a subject has had UI in the last 3 months and its type [stress urinary incontinence (SUI), urge urinary incontinence (UUI), or mixed urinary incontinence (MUI)] according to the trigger situation (stress, urge, or no physical activity) [18, 19]. The UI type is defined according to the responses to question 3, with the following possibilities and interpretation: A, “you leak urine most often when you were engaged in physical activity (e.g., coughing, sneezing, lifting, exercising)” (SUI or predominantly SUI); B, “you leak urine most often when you had the urge or feeling that you needed to empty your bladder but you could not get to the toilet fast enough” (UUI or predominantly UUI); C, “you leak urine most often without physical activity and without a sense of urgency” (other causes or predominantly other causes); or D, “you leak urine about equally as often with physical activity as with a sense of urgency” (MUI) .
Incontinence Severity Index (ISI) (Spanish version)
This consists of two questions about the subject’s experienced frequency of urine leakage (5 levels) and how much urine is lost (4 levels) described as none, drops, small splashes, or more . This incontinence severity is based on data after multiplying the results of the two questions, as follows: slight (score 1–2), moderate (score 3, 4 or 6), severe (score 8–9), or very severe (score 12) .
For athletes’ specialization, track and field events were grouped according to the main sport activity required. For the classification, Olympic events were considered as follows: sprint/hurdles (100 m, 200 m, 400 m, 100 m hurdles [mh], 110 mh, 400 mh, and relays); middle-distance running (800 m, 1500 m, 3000 m, and 3000 m steeplechase); long-distance running (> 3000 m); athletic walk (20 and 50 km); horizontal jumps (long jump and triple jump); vertical jumps (high jump and pole vault); throws (discus, javelin, hammer, and shot put); and combined events (decathlon).
All statistical tests were performed using the package IBM SPSS Statistics v.26.0 (New York, USA). Data are provided as the mean and standard deviation along with 95% confidence intervals (95%CI). When appropriate, data are provided as percentages. The Shapiro–Wilk test was used to check the normality of the data. Between sexes, means were compared using the Student's t test and proportions by the Chi-squared test. The estimated odds ratio (OR) and 95%CI for the OR were analyzed through the risk estimate of crosstabs. One-way ANOVA was used to test the profile of the values, depending on the track and field events in which they are specialized. Bivariate correlations among quantitative variables (demographic, training characteristics, number of pregnancies, and ICIQ-UI-SF) were assessed through Pearson’s coefficient. The level of confidence was set at 95% and significance at p < 0.05.