I would appreciate any idea or tip(s) so as to overcome second toe black nails on my right and left foot under certain circumstances. Given the following: Foot length: 28cm I buy shoes at 29.5cm (size US 11.5 usually), Weight: 92Kg (approx.), Protective toe caps used for both toes, Running socks used (Adidas, New Balance, Mizuno, Nike).
The problem arises when running over 15Km (9,3miles) and not with all running shoes!!! I have noticed that shoes with a high flexibility factor (not stiff) in the longitudinal and torsional axis are better for me. I have run a Marathon and a Half-Marathon with no problem at all when I used i.e. Adidas Solarboost (Model: B96286, which is really very flexible in the forefoot). In contrary, using Hoka Clifton 8 even when running 15Km will end up with a second toe nail pain in either foot. In addition, Brooks Ghost 14 although they are quite flexible I have run two half-marathons (road races) of which the first ended up with black nails in second toes while the second didn’t!!! Is there any idea to overcome this problem?
Further info/sources: https://runrepeat.com/guides/flexible-vs-stiff-running-shoes https://runrepeat.com/guides/soft-vs-firm-running-shoes