Review of how we should define (and measure) adherence in studies examining older adults' participation in exercise classes

There was little consensus between studies on how adherence should be defined, and even when studies used the same conceptual measure, they measured the concept using different approaches and/or had different cut-off points. Adherence related to health outcomes requires multiple measurements, for example, attendance, duration and intensity. It is important that future studies consider the outcome of the intervention when considering their definition of adherence, and we recommend a series of definitions for future use.