Strength and limitations
hypotension
A strength of the study is that the comparability of HR and BP between the two VR sessions is very high due to the identical study population.However, there are also several limitations. Unfortunately, the calculated sample size could not be met due to the refusal of certain potential participants to take part in the study as a result of the COVID-19 pandemic.The study's main limitation is the absence of a control group. Without a control group or session for comparison, it is challenging to attribute the observed changes in the dependent variables solely to the experimental treatment. This absence introduces potential threats to internal validity, such as maturation and selection bias. Despite this limitation, the study provides valuable insights into the effects of the treatment within the VR sessions.Another limitation of the study is the lack of randomization of the two VR sessions. Although each participant had the VR-SET in the first week (visit 1) and the VR-ET in the second week (visit 2), the order of the VR sessions may still have had an influence on the perception of them. The order of the sessions could potentially confound the results as the experience gained influences the behavior of the participants during the second session. By not employing randomization, the study may be prone to allocation bias.One further limitation was the lack of blinding in the study. Blinding of studies in physical and rehabilitation medicine is particularly complex compared to other areas of medicine [Furthermore, there are recommendations for the determination of postexercise hypotension, which state that a measurement should be taken at least up to 20 min, or even better 120 min after training, to assess the effect [In addition, at this stage of the project, the VR exergame was not yet completely developed, which meant that the ACSM recommendations of a minimum of 30 min of aerobic exercise or moderate-intensity strength exercise [Another point of concern relates to the individuals chosen to take part in the VR sessions, which could have an impact on HR and BP. Conjectures suggest that older people might be afraid or excited due to the low acceptance of VR technologies. However, the results from other publications suggest that VR applications with regard to the health of older adults are not affected by negative attitudes [A further significant limitation in the consideration of the load intensity and BP relates to the medication. In the evaluation of the results, a more detailed consideration of the influence was omitted. However, as described, β-blockers and angiotensin II receptor blockers, among others, lead to a reduced HR at rest as well as during exercise [Although the results of the Simulator Sickness Questionnaire (SSQ) [Furthermore short signal interferences of the VR headset, which resulted in additional breaks, could lower the load intensity. Even though the Polar M600 is considered suitable, erroneous measurements cannot be excluded. However, to preserve internal validity, the same watch was always used.