## 1 Introduction  
Distance running performance can be influenced by a variety of shoe factors. Multiple studies have reported that certain footwear characteristics, such as shoe mass, midsole bending stiffness (MBS), and foam midsole material, can influence both physiological [1; 2; 3; 4; 5] and biomechanical variables [6; 7; 8]. This, in turn, may result in positive changes in distance running performance. Running economy (RE) is a determinant of distance running performance and is defined as the rate of oxygen consumption at a given velocity of submaximal running [9; 10]. Shoe mass is a frequently examined footwear property that is related to RE and performance. Greater shoe mass can lead to increased energy consumption and thus to a reduction in RE [1; 11]. In 3000 m time trials, [PERSON] et al. [1] showed that RE degrades and running time increases 0.78% for each additional 100 g per shoe. Furthermore, previous research found that heavier footwear has significant effects on biomechanical parameters such as ankle joint angles, ankle moments, and plantar pressure during running [12]. The effect of increased MBS is considered a key factor for optimizing running shoes. It is closely linked to individual runner characteristics (e.g., anthropometrics, strength capacities, running style), but also related to running speed [13; 14] and the rollover feeling [15]. It has become increasingly common to use carbon fiber plates in running shoesto increase MBS to improve distance running performance [6; 7]. Recent analyses have shown that these technological advances in running shoes have resulted in significant improvements in international half marathon and marathon best times among world-class athletes [16; 17]. However, research shows inhomogeneous results of the effects of MBS on RE. According to the findings of [PERSON] and [PERSON] [18], carbon fiber plates in running shoes can reduce the energy cost of running by approximately 1%. This varies depending on the plates' design (e.g., curved, flat, length) [19]. Recent studies have found that running with the \"Nike Vaporfly 4%\" can lead to an increased running economy of approximately 4% on average [6; 20]. In addition to varying MBS to improve running performance, several studies have investigated the effects of midsole stiffness [5; 21], midsole thickness [22] and midsole structure [23]. However, [PERSON] and [PERSON] [24] found that the curved carbon fiber plates only play a small role in the 4% metabolic savings generated by the \"Nike Vaporfly 4%\". The authors suggest that the savings likely result from a combination of and interaction between the midsole foam, shoe geometry, and plate. From a biomechanical perspective, research shows that increased MBS reduces negative work at the metatarsophalangeal (MTP) joint and influences joint mechanics in the ankle and knee [7; 25]. Furthermore, [PERSON] et al. [7] concluded that the energy savings from the curved carbon fiber plates provided a clever lever effect on the joint ankle mechanics, a stiffening effect of the plate on the MTP joint, and superior energy storage in the midsole foam. However, current studies have reported conflicting results in terms of biomechanical variables [26]. Results of spatiotemporal parameters (e.g., ground contact time or step frequency) were inhomogeneous [6; 7; 8; 20]. It can be concluded that there is currently no plausible explanation for improved running performance based on biomechanical parameters. To the best of the authors' knowledge, there are only few studies that have investigated the influence of different footwear conditions on both physiological and biomechanical variables simultaneously during endurance runs longer than 1 km. However, it seems necessary to examine the long-term effects of the different shoe components on running performance in order to be able to explain (half-) marathon personal best times using physiological and biomechanical variables.