Triathlon is a popular sport for both recreational and competitive athletes. This study investigated the rates and patterns of stress fractures in the German national triathlon squad. We developed a web-based retrospective questionnaire containing questions about the frequency of stress fractures, anatomic localisation and associated risk factors. The survey was conducted as an explorative cross-sectional study. Eighty-six athletes completed the questionnaire. Twenty athletes (23%) sustained at least one stress fracture. All documented stress fractures were located in the lower extremities. Factors associated with a higher risk for stress fractures were female gender, competitive sport prior to triathlon career, Vitamin D or iron deficiency, menstrual disturbances and a high number of annual training hours. Disseminating knowledge among athletes and their professional community in order to raise awareness about early symptoms and relevant risk factors could help to improve prevention and reduce the incidence of stress fractures.

Background: To date, it remains unclear which oral doses and preparation forms of melatonin should be recommended for children and adolescents with non-organic sleep disorders and autism spectrum disorder (ASD). We reviewed the current state of knowledge on this topic based on randomised placebo-controlled trials (RCTs) and diagnosis-related blood melatonin concentrations available in this age group. Method: Two investigators independently searched PubMed, PsycINFO, MEDLINE, and Cochrane CENTRAL on 1 March 2025 for the keywords “melatonin”, “autism”, and “randomised” in titles and abstracts in all languages, including an evaluation of the references of the reviews, systematic reviews, and meta-analyses published up to that date, some of which were based on searches in numerous databases. Based on this, additional in-depth searches were carried out in PubMed for pharmacokinetic, physiological, and pathophysiological data on melatonin in children and adolescents, with a special focus on ASD. Results: To date, five RCTs on non-organic sleep disorders in children and adolescents with the sole diagnosis of ASD or with subgroup analyses in the presence of several initial diagnoses such as ADHD, epilepsy, Smith–Magenis, or Fragile X syndrome are available. In these studies, rapid-release, non-delayed preparations were administered orally. In one of these studies, the clinical efficacy of a combination preparation with a sustained-release and a non-released active substance component was tested. Pharmacokinetic data with multiple determinations of melatonin concentrations in the blood are only available for children with ASD in the form of a case series (N = 9). Discussion: RCTs comparing the efficacy of delayed melatonin preparations with non-delayed rapid-release oral preparations are not yet available. Physiological data and clinical effects documented in five RCTs indicate that non-delayed melatonin preparations with an initial rapid onset of action are effective for non-organic sleep disorders in children and adolescents with ASD. Conclusions: From a clinical, pharmacokinetic, and physiological point of view, the RCTs available to date and the data on melatonin concentrations in the blood of children with ASD, measured several times over 24 h, suggest that a low oral melatonin dose and a non-delayed preparation with rapid onset should be started in children and adolescents with non-organic sleep disorders in ASD, if sleep hygiene advice and psychotherapeutic interventions have not demonstrated sufficient effects.