According to RRCA (Road Runners Club of America)’s fundamentals of youth running, general guidelines per age group are as follows.
From ages 3-9 years – Regular exercise is encouraged along with organized running which is fun.
Children under 5 can participate in kids fun runs.
Ages 8 -12 years – can participate in a running group with systematic training which lasts 2 -3 months.
Around puberty – children can slowly increase training distances and participate in competitive training.
However, these guidelines can vary depending on each child’s abilities and fitness level.