In competitive swimming, training is often described by distance completed per practice or per week. Sports science literature, however, uses the broader concept of training load to describe how much stress training places on an athlete (International Olympic Committee, 2016).
Training load is typically divided into external load and internal load. External load refers to the measurable work performed, such as total distance swum, number of repetitions, intensity of intervals, and duration of training sessions (USA Swimming, 2023). Internal load reflects how the athlete’s body responds to that work, including physiological strain, fatigue, and perceived effort (IOC, 2016).
In swimming, external load is often tracked through total yardage or meters, stroke distribution, and intensity zones. Internal load may be monitored through heart rate data, rating of perceived exertion scales, and recovery indicators reported by the athlete (World Aquatics, 2022). Research across endurance sports shows that two athletes completing the same external workload can experience very different internal responses based on age, training history, sleep, and recovery status (IOC, 2016).
Because performance adaptations occur only when training stress is followed by adequate recovery, understanding training load is central to responsible program design. Excessive load without sufficient recovery has been associated with performance stagnation and increased injury or illness risk, while insufficient load may fail to stimulate adaptation (USA Swimming, 2023).