Delayed Onset Muscle Soreness (DOMS) – The pain felt in the muscles the day after exercise

Her train was delayed, so she had to run, bringing about an onset of muscle soreness (delayed onset muscle soreness) the day after.

Delayed onset muscle soreness is caused by eccentric contractions of the muscles resulting in small-scale damage to the muscle fibres. This can be a sign of a good workout as well as a warning sign to ease off and prevent injury.