Introduction
Cardiorespiratory fitness, often expressed as maximal oxygen uptake (A recent meta-analysis [These findings highlight the profound effect of an individual’s genotype on the degree to which they respond to exercise. However, a major limitation in many of the studies included in the meta-analysis was that improvements in health-related fitness components were often linked to a particular gene, rather than any allelic variation of that gene. Accordingly, there is a relative paucity of research investigating the influence of gene-specific polymorphisms on exercise responses [The aim of this study was to engage a previously untrained population of UK adults in an 8-week endurance training program and investigate the influence of allelic variation on cardiorespiratory fitness responses through a proprietary chip containing 1,000 single nucleotide polymorphisms (SNPs). The objectives were to identify specific SNPs associated the increase in cardiorespiratory fitness, rather than the bias “handpicking” of common well explored ‘candidate genes’ and whether possessing multiple of these ‘favorable’ SNPs increased an individual’s training responsiveness. This study was performed during the onset of the COVID-19 pandemic and, therefore, had to be conducted in a field-based setting as opposed to a standard laboratory environment due to the inability to access the latter for an indefinite amount of time. However, there is a growing body of literature focused on how home-based exercise training can be implemented to combat physical inactivity and to promote improvements in health-related outcomes, including cardiorespiratory fitness [