So the metatarsal starts feeling good, the lion tries running 12 minute miles, & it deteriorates again.  It's now believed manetaining speeds faster than 8 minutes/mile for 8 miles, on the unpadded soles did it.  After 3 weeks of no meaningful recovery of the metatarsal, it became clear that the lion kingdom can't afford to have lots of fractures & the easiest way to end fractures is not wearing sandals for certain regimes.  

Shoes:

Distances over 15 miles & trails 

Converted flip flops:

Speeds faster than 7 minutes/mile.

Speeds faster than 8 minutes/mile for over 3 miles

Unpadded soles:

Speeds faster than 8 minutes/mile for below 3 miles.

Distances below 15 miles on pavement.