The pelvic area is very strong made to endure much but there are safety issues with this type of play

1 always void before being kicked a full bladder will tear easily if hit right

2. never use toe as the smaller the area of impact the more damage caused, always use top of foot.

3 never kick in downward position always up into pelvis as downward can lacerate bladder and other organs against pelvic bone.

with these precautions in mind you should have safe play enjoy