Once your child is at least 9 months old and is able to sit upright unassisted, they should be ready to ride in the Avi while it is being pushed at a running pace. However, every child is unique and develops at a different rate. If you are uncertain whether your child is ready to ride in the Avi, please consult your pediatrician prior to running. The seat unit is not suitable for children under 6 months. If you would like to use the Avi at an earlier stage, you can simply attach any CYBEX or gb car seat with adapters (sold separately). In this way, the Avi can be used as a conventional stroller at a normal walking pace. The Avi must never be used for jogging or running when an infant car seat is attached. Specific running instructions can be found in the warning booklet supplied with the product.