A technical note on challenge tests in human volunteers for multidimensional phenotyping

Challenge tests are used to reveal the adaptability and resilience of humans to get insight in their health. When contrasting challenge tests are used, various forms of adaptability can be tested and this gives a multidimensional view on the health of these individuals. Here we introduce a methodology to describe the similarities and differences on how individuals are positioned in the health space based on the responses to different challenge tests. Results show that anabolic and catabolic challenges differentiate healthy subjects in rather different ways. Considering these results we hypothesize that combining challenge tests can improve the understanding of the underlying multidimensional phenotype.