A training plan is a complex mix of many interventions that often change over time due to periodization. In contrast to a “drug or no drug” decision in medicine, it is virtually impossible to base all of the underlying decisions on scientific evidence.

An alternative to a fully evidence-based approach is an evidence-informed approach where only some training plan decisions are based on the currently best available evidence.

Many training adaptations vary greatly. Until robust trainability biomarkers are identified, practitioners should continue to test athletes, clients, or patients and monitor training variables to re-plan if a training prescription does not yield the desired adaptations.