I know that losing a nail occasionally is an occupational hazard from running. However, I find that I am losing a nail on almost every big run (40km+)
Sometimes there is an obvious injury to the nail, but often my nail just goes black and falls off
I haven’t experienced a repeat nail failure, it’s always a new nail that I lose. Now on my 6th nail. 3 this year
All normal, especially in trail running where your toes can get hammered on steep descents. Don’t think I’ve had a full set of toe nails for over two years now.
or do you mean you are losing the same nail over and over?
No I’ve never lost the same nail twice. Always a different one
Glad to hear that I am not alone
2 of my 3 losses this year were trail running
Only since i’ve started doing very long ultras. Had never lost one before my first 100miler. Don’t think i lost anything on the next one, but then lost 2 on my 3rd (almost) 100 miler. The latest lot took 10 months to totally grow back to normal (i had a nail under a nail for ages, and all sorts of interesting stuff going on).
I’ve had a couple of times before road running but nothing like when I took up trail running. Also, let them fall off, don’t be tempted to ‘help them’ because it really hurts afterwards!
No way am I ever pulling one off shuddering just thinking about it
That’s not normal. Are your shoes too small? Unlaced if you push your toes to the front of the shoe you should be able to get a finger between the back of the shoe and your heel.
Yeah, totally agree with that.
Are you using the “heel lock” lacing method to keep your foot back?
I know a few of your runs are fairly hilly, so you probably want to keep your foot back in the shoe, to leave a bit at the end.
My feet swell over duration, so after a marathon, they are a bit larger.
A well fitting shoe for 10km - half marathon is not a good shoe for anything over 2.5 hours, or at least that’s my experience.
I have recently sized up due to my feet getting wider, So shoes should be big enough. I have not tried heal lock lacing before, but will also give that a go.
Lots of my runs are hilly. the recent run I did, although pretty flat on average did gave one big decent on gravel and I pushed pretty hard down here, as I had a foot injury over the September, I left laces pretty loose near the the box, as a result I think that my feet may be moving forward and smashing against the front of the shoe on descents. Now I am fully recovered, I probably need to re-lace my shoes
Yeah, that’s what I do, but you lace them tighter at the top - where your heel/ankle are.
It’s this “tightness” that prevents the foot slipping forwards.
I always use heel lock lacing. It seems really common on trail running forums, so we need to make sure we aren’t mixing up road running with the demands of trail, as they are vastly different.
I size up half a size for some trail shoes, not others, it purely depends on the make and model.
or just stop braking on the descents and then your feet will stay where they’re supposed to be 
There is that. I also find things like very hard rutted single or narrow track have my feet at weird angles. Long grassy descents with rabbit holes and tussocks are where I find it hard not to brake and tend to descend them sideways and swap sides but that kills the sides of your feet also.
Alternatively are your shoes too big ?
If your shoes are not tight enough the foot can slip around a bit and the toes may hit the inside of the shoe. The heal lock lacing may help.
Both too small shoes and too big can cause problems.