Training load

Training load is a quantified measure of how much physical stress a single workout, or a period of training, places on the body, combining how hard the effort was (intensity) with how long it lasted (duration). It is used to track how much work an athlete is accumulating over time, distinct from any single performance metric like pace or power output in isolation.

Load is calculated different ways depending on the sport and data available: a simple version multiplies session duration by a subjective effort rating (session RPE), while heart-rate- or power-based methods weight duration by intensity zone using heart rate or power data. Acute load (recent days) is often compared against chronic load (recent weeks) as an acute:chronic workload ratio, used to flag when training volume is rising faster than the body has adapted to.

Coaches and athletes use training load, alongside recovery signals like heart rate variability and resting heart rate, to guide load management decisions about when to push training and when to back off, since a rapid spike in load is associated with elevated injury risk. A common pitfall is comparing raw load values across different methods or devices, which are not interchangeable, and treating load alone, without recovery context or VO2 max trend, as sufficient to judge training readiness — this is fitness tracking, not medical guidance.