What is the term used to describe a reduction in training load leading to decreased fitness?

Detraining refers to the phenomenon where an individual experiences a reduction in fitness levels due to a decreased training load or a cessation of regular physical activity. This term encapsulates the idea that when the body is not subjected to the same stimulus it received during consistent training, it cannot maintain the adaptations developed over time, such as cardiovascular endurance, muscle strength, or flexibility.

When a person reduces their training intensity, frequency, or duration—even for a short period—the body starts to revert to its pre-training state, leading to declines in performance and fitness. This is particularly evident in aerobic capacity, strength levels, and other physical attributes developed through regular training. The physiological response to this decreased training load results in less efficient muscular and cardiovascular systems, which exemplifies why the term "detraining" is appropriately applied in this context.

Other terms relate to different concepts; for instance, overtraining refers to excessive training without adequate recovery, leading to negative symptoms, while undertraining signifies insufficient training volume to achieve fitness gains. Recovery, on the other hand, is an essential component of training that allows the body to heal and adapt, but it does not imply a reduction in load that leads to fitness loss like detraining does.