Hi Natalie8,
Amazing story, isn't it
Although I don't run I understand Kayla's experience. She is pushing beyond her limits and once she stops she collapses so she needs someone at the end of her run to catch her.
It's not much different than my own experience in walking beyond what is comfortable for my body. I have stressed to my husband I cannot stop when we go walking if I do I need to sit immediately or I will collapse.
I hope Kayla has the ability to run for many more years.