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Factors Influencing Iron Metabolism in Female and Male Athletes
(2026-01) Nolte, Svenja
“Athletes are at risk for iron deficiency” has long been the dominant narrative in sport science when bringing iron and athletic performance together. This perspective is not unsupported, prevalence data speak for themselves, but it seems to shrink a highly complex physiology into a single outcome. Iron metabolism represents a tightly regulated network that underlies complex regulatory mechanisms. Its involvement spreads across multiple physiological systems, including the hematological and immune system, energy metabolism and oxygen transport. This large involvement creates a platform that increases its susceptibility to influencing factors. Athletes with their extraordinary lifestyle place unique stress on iron homeostasis, often have elevated iron requirements and may therefore be particularly susceptible to iron deficiency. High training loads, exposure to hypoxia, altered energy availability, and sex-specific factors are only a few factors placing substantial influence on iron balance. Therefore, this dissertation project set out to investigate these interacting dynamics, rather than treating iron deficiency as an isolated endpoint. The aim was to advance the mechanistic understanding of iron regulation, and to inform evidence-based practical guidelines. To address this aim, the dissertation integrates evidence from a narrative review and multiple original empirical studies conducted in athletic populations. The project opened with a narrative review synthesizing current knowledge iron-related challenges and practical prevention methods for iron deficiency in athletes. This background guided three original studies on distinct but interrelated stressors of iron homeostasis. Under controlled normobaric hypoxia, athletes demonstrated increased erythropoietic iron demand alongside alterations in immune-related markers, highlighting competition for iron between physiological systems. Menstrual blood loss appeared as a recurrent iron stressor in female athletes, showing that despite chronically lower ferritin concentrations, hematological function and oxygen transport capacity were maintained, indicative of adaptive iron redistribution. Finally relative energy availability was identified as a key determinant of systemic iron status in elite athletes, linking metabolic strain to reduced iron stores independent of dietary iron intake. Taken together, this cumulative work places iron within the framework of network physiology. Iron emerges not as an isolated hematological variable, but as a dynamic mediator within an interconnected system of adaptations, in which influencing factors force a regulated symmetry under sustained demand. This perspective provides a conceptual basis for a broader yet more specific monitoring and management strategies that account systemic interactions.
Utilization of Hydrometeorological Participatory Monitoring in Data-Scarce Remote Tropical Mountainous Regions
(2026-01) Mitze, Fabian
Climate change is an ever‑present anthropogenic problem that affects all regions of the earth. Reliable hydrometeorological data are essential for the evaluation of the impacts of climate change, with a robust data basis providing a foundation for climate research and the development of mitigation and adaptation measures. Ground-based monitoring stations that provide such data are distributed very unevenly across the globe, and remote sensing methods may be limited in terms of spatial or temporal resolution for specific applications. This is why there is clearly a need for alternative monitoring approaches, particularly in remote tropical mountainous regions that may lack the necessary resources. Participatory monitoring, in which the public is involved in data collection, might be part of a cost-effective solution. Therefore, this work aims to investigate, how hydrometeorological participatory monitoring can be used for (1) efficient hydrological model calibration, (2) alternative observation of different hydrometeorological parameters and (3) enhancing the accuracy of other observational datasets. This methodology was tested in remote tropical mountainous regions in Ecuador, Honduras, Kenya and Tanzania, where conventional data collection methods are severely limited or unavailable. The first chapter of this dissertation analyzes how many daily participatory monitoring water level measurements at what stages of the hydrological cycle are required to achieve satisfactory hydrological model performance. A simple rainfall-runoff model was used to test this in a tropical mountainous catchment in Kenya. The analysis shows that the starting conditions of the monitoring (wet vs. dry season) influence the required amount of data. Good model performance was achieved within one month when monitoring started in the wet season, while multiple months were required when starting in the dry season. The subsequent chapter evaluates (1) how the ability of measuring air temperature, relative humidity, rainfall and water level using simple analog sensors differs between frequent and non-frequent participants and (2) how suitable the analog sensors are in terms of accuracy compared to automatic sensors. Between May 2023 and May 2025, 2,982 hydrometeorological observations were received from 52 low-cost stations in Ecuador, Honduras and Tanzania, of which frequent participants submitted the majority (84.4%), with slightly better accuracy. The analog sensor measurements showed mixed results when compared to automatically measured data. Air temperature and water level performed best with the lowest mean absolute errors (0.74 – 1.65 °C; 0.04 – 0.08 m) while relative humidity data required correction to obtain moderate accuracy (5.45 – 9.50 %) and rainfall was generally underestimated (2.55 to 3.10 mm). In the final chapter, the use of the participatory monitoring air temperature data from the previous chapter to bias‑correct a large‑scale continuous air temperature data was tested. Simple linear regression models were trained using ERA5-Land reanalysis and participatory monitoring air temperature measurements from one station in Ecuador (n = 67), Honduras (n = 23) and Tanzania (n = 275). The models were then used to correct the ERA5-Land air temperature bias over a period for which automatically measured hourly reference air temperature data was available (up to one and a half years). ERA5-Land air temperature bias was reduced at all stations, but with varying degrees. The most significant reduction was obtained in Ecuador, with the mean absolute error decreasing from 5.49°C to 1.76°C. To conclude, this research shows that hydrometeorological participatory monitoring has the potential to improve overall data availability in remote tropical regions with limited financial resources. The knowledge gained from this research could help to inform future participatory monitoring programs and strengthen the acceptance of data collected using such alternative approaches.
Zimmer 9 - Ein persönlicher Case Report
(2026-06-26) Kalic, AmmarUncovering Medicine
Ein Jahr ohne Hilfe - Auswirkungen des Verlusts von USAID auf Malawis Gesundheitssystem
(2026-06-25) Melin-Filz, JuliusUncovering Medicine
Wohlstand und seine blinden Flecken - Gesundheit im Strafvollzug
(2026-06-24) Jecht, Katharina HenrietteUncovering Medicine