I recently developed a new pain in the middle of my foot. It feels like a bruise deep in the ball area of the foot under the third metatarsal. From what I’ve read, I suspect Metatarsalgia.
Has anyone had this? If so, what’s the treatment? Can I train through it? Biking versus running? Any advice would be apprecitated.
As is usual, you “should” rest it. As a realist, triathlete and Podiatrist: yes, you can train through it. Obviously, more swimming now is good, etc…
Get some 1/4" sticky felt - cut it in the shap of a horseshoe. Place the “arms” towards the toes with the metatarsal head (sore bruised spot) in the middle of the horseshoe. Stick it directly to your foot. Play around a bit until you get it right. Ice the ball of the foot with a frozen styrofoam cut of water. Should be better within 10-14 days.
This is, of course, the presuming diagnosis is correct. Can’t do much harm with the above advise so … 
Spot tenderness plantar to the 3rd met is usually this, although Metatarsalgia is a “junk” medical term used for any “ball of the foot” pain that is not more specifically classified (i.e. Morton’s neuroma, capsulitis, stress fx, plantar (volar) plate tear, etc.)
good, 1/4" adhesive felt is hard to find and I stand by my offer before, anyone that needs some, I’ll send some over for free - just paypal me a couple of bucks for shipping (rroof@cinci.rr.com). Nothing brings a smile to my face like happy triathlete’s feet Really, I’m weird that way (although I don’t have a true foot fetish, but I sure wish I did)
Thank you for the help and advice. Check your paypal acct.
– joe
Jobo: i did have same experience - accelerated by forefoot of my shoes breaking down prematurely.
So i came up with the same engineering solution as rroof; but rather than 1 layer of 1/4" felt, i put on 3 or 4 layers of Dr. Scholls’s Moleskin Plus on the insole, partly overlapping.
Another difference: i cut an ellipse (approx. 1" x 3/4") of this felt-like moleskin that i stick on the insole, behind the metatarsal head that’s bothering. The point of this is to unload that metatarsal head by loading the arch behind it slightly (without having any other material under the ball of my foot).
this worked well for me and some other folks that had the same issue - although rest, icing etc. works best … if i ramp up long runs, then i need this felt in my shoe. I have not had side-effects or irritation from this otherwise.