It wasn't easy!!!!!!
What a difference an extra 30 seconds make!! Not too bad with the huffing and puffing but due to my lack of fitness I tend to get this feeling that my calf and shin muscle/s are almost cramping, as if the blood can't get around enough???? It goes away when I walk and starts by about interval 4.
It has happened before so I know it's not long lasting, muscular or shin splints.
HOWEVER, I did it
Good luck Alliecat