###### Abstract  
Virtual and augmented reality (VR/AR) exergames are promising tools for increasing training motivation. However, the use of exergames with mixed reality (MR) headsets remains under-researched. Older adults with hypertension could also benefit from the increased training adherence associated with MR. Endurance and strength endurance exercises are recommended for this group to lower blood pressure. The aim of the preliminary study (\(n=22\)) was to compare the usability and acceptance of two exergames, which represent two different training types--strength endurance training (SET) and endurance training (ET). The developed exergame prototypes were applied in \"simulated MR\" using a VR head-mounted display. We examined the following outcomes: usability (TUI), intention to use (TUI), subjective task load (NASA-TLX), frustration (NASA-TLX), and presence (PQ). The results showed that frustration was significantly greater in the ET than in the SET (\(p=0.038\)). Presence was significantly higher in the SET (\(p=0.002\)). No significant differences in usability and acceptance were found in the exergames. The results indicate that usability and acceptance are not related to the type of training when utilizing MR exergames. Whether the results are transferable with a real MR headset must be determined in further research. virtual reality; hypertension; rehabilitation; UX; presence; immersion +
Footnote †: journal: Medical Gerontology, Charite--Universitatsmedizin Berlin,  
this reason, a user-centered design (UCD) was developed in the project. As recommended in a systematic review by [PERSON] et al. (2018), it is advisable to involve elderly people from the initial steps onward, including collecting the essential specifications for the framework. The papers of [PERSON] et al. (2018) and [PERSON] et al. (2018) described the requirements for the system and movement training. In the current paper, the usability and acceptance of two types of training will be compared using a functional VR prototype developed based on the requirements gathered previously. In the requirements analysis, [PERSON] and [PERSON] showed that AR exergames should focus on the endurance component, as well as other concepts, and adapt training to the user's health profile and fitness level through precise training control via heart rate monitoring. The older adults wanted an interactive exergame with motivating, playful elements. The results suggest that many seniors would prefer an AR system to a VR system because of the lower risk of falls. Furthermore, a requirement of the experts was that four to five 30-min training sessions be carried out per week. A virtual agent was the first solution to the requirement of a multiplayer exergame. Due to the existing limitations of AR/MR headsets, such as the field of view in the HoloLens, the consortium decided to implement a high-fidelity prototype VR that simulates an ideal MR. Since the definition of MR is ambiguous in the scientific community, it is first necessary to define what is meant by it in this paper. [PERSON] and [PERSON]'s reality-virtuality continuum (2018) introduced the term \"mixed reality\". They defined MR as a subset of VR-related technologies that involve the merging of real and virtual worlds regardless of the environment. [PERSON] et al. (2018) revised [PERSON] and [PERSON]'s reality-virtuality continuum, considering the new technological possibilities, and provided a new taxonomy for describing MR experiences with dimensions including the extent of world knowledge, immersion, and coherence. [PERSON] et al. (2018) conducted expert interviews and a literature review from which six notions of MR were derived. As a consortium, we considered MR to be a \"stronger\" version of AR involving possible interactions between the user and the virtual objects as well as the latter and the real environment, as described by [PERSON] et al. (2018, 2019).