Maybe in book by Kari, Bo et al 2015 Evidence based physiotherapy for pelvic floor muscles. Although I don't  see the connection because in horseback riding important muscle groups are thigh adductors, gluteals, guadriceps, core muscles...just my oppinion.

Hello Peggy

I had heard of this concept, but apart from non-academic sites, could not find any evidence. As mentioned above, Kari Bo has looked into this:

Bø, K., Hilde, G., Jensen, J. S., Siafarikas, F., & Engh, M. E. (2013). Too tight to give birth? Assessment of pelvic floor muscle function in 277 nulliparous pregnant women. International urogynecology journal, 24(12), 2065-2070.

This is the full text and below is the RG entry:

https://brage.bibsys.no/xmlui//bitstream/handle/11250/218678/KBoIntUrogynJ2013.pdf?sequence=1

https://www.researchgate.net/publication/237094350_Too_tight_to_give_birth_Assessment_of_pelvic_floor_muscle_function_in_277_nulliparous_pregnant_women

The conclusion is that: 'strong pelvic floor muscles are not disadvantageous for vaginal delivery'.

Very best wishes,

Mary

Article Too tight to give birth? Assessment of pelvic floor muscle f...

Thanks for your help, I've just asked Kari and she said also it's a mare. But it would be interesting to do some research in horseback riding women. And she agrees with Nebojšas comment.