independent training; self-directed practice
Abbreviation of 自主トレーニング. Refers to voluntary, self-organized training, often by athletes outside of formal team or coach-led sessions.
See also: 自主トレーニング
オフシーズンは自主トレで体力を維持している。
During the off-season, I maintain my fitness through independent training.
彼は毎朝、自主トレとしてランニングをしている。
He goes running every morning as part of his self-directed practice.
Abbreviation of 自主トレーニング (jishu torēningu), itself a compound of 自主 (jishu, 'self-directed') and トレーニング (torēningu, 'training').