Maybe try metatarsal pads?  If it's the ball of your foot, you might try those.

I have a neuroma in my left foot that causes the ball of that foot to go numb after about 5-6 miles, then it starts burning at around 10-11.  Both my PT and a podiatrist both recommended a metatarsal pad. These go into your shoes (and if you get the right ones, they'll stick right onto your existing inserts) and they get placed NOT on the ball of your foot, but just behind them. The purpose is to lift the metatarsal bones so they dont hit as hart .. (or something like that). I've only been wearing mine a few days but I am seeing some improvement. Not 100%, but it does seem a bit better.

I had read about these pads and got over the counter ones, but they moved all over the place in my shoes. The podiatrist I saw gave me medical grade ones. I've run in them 3-4 times now, and they have not budged. 

Here's the website where you can get them. They're much cheaper than one's you'd buy at like Walgreens or CVS and they stay put much better too.

hapad.com

(now granted, this is all assuming you have a neuroma too.....)

This has happened to me off and on over the years.   

It seems like it comes and goes and, but as a general rule, I have noticed that I will get numbness (foot going to sleep) around the 3rd mile under two circumstances.......1) I haven't been running much or consistently enough.....2) I get a new pair of running shoes.......

Normally some consistent running over a couple of weeks and the problem magically has gone away for me.....

In the off-chance that it's something shoe-related ... you might also look at Lydiard lacing or switching to elastic laces (I like the iBungee by Easy Laces, but Lock Laces and Yankz are out there, too).  You can relieve a lace-induced pressure point by alternative lacing patterns, or distributing the lace pressure via stretch laces (the latter is working really well for me).

As the comments in your log say, ease up!  A quicker cadence doesn't have to mean speeding up -- try running at ~9min/mi pace, then take shorter strides ... but more of them per mile.  You'll still be moving at 9min/mi pace, but with a cadence nearer to what you've been chasing.  And you'll put less strain on your lower legs, which may be the numbness culprit.

Good luck!

In the off-chance that it's something shoe-related ... you might also look at Lydiard lacing or switching to elastic laces   

YES I agree --- I forgot to mention (or completely forgot) that I did start using Lydiard lacing and that also made a big difference for me........you ought to consider trying that too....

http://www.lydiardfoundation.org/training/lacingthelydiardway.aspx

I just saw our local shoe guru/gait analysis expert (my running club buddies all call her the "Shoe Whisperer").  I have Morton's Neuroma, which causes your foot to go numb initially then turns to burning pain or other worse pain for some.

She recommended 3 things (assuming you have a neuroma)

1.  ProKinetics inserts.  These come with an optional additional lift that goes under your big toes that increases the lift to 6.0mm. Use it.  Most neuromas seem to be caused by a longer 2nd metatarsal bone, so you're pushing off with your smaller toes, versus your big toes like you're supposed to.  The ProKinetics inserts shifts things around to encourage your foot to push off with your big toe. (I'll warn you though, using this causes your body alignment to change -- which ultimately is good, but it makes you a bit sore for a while.  I also have gotten some blisters)

2.  Get Yoga Toes and use them 3--4 times per day while icing your foot.  The Yoga Toes spreads your toes out and exposes the nerves, giving them a chance to heal, especially when you ice them.

3.  Make sure you're wearing shoes with a wide toe box.  Wendi advised me to never again wear Nikes or Asics, as they have air and gel and tend to form to the foot and can compress nerves that are more surface in some people.

I'm only a few days into using all of the above. But ... I did my first 12 mile run in them on Sunday, and I actually got through all 12 miles without screaming pain.  My foot did start to go numb in the latr miles, as before -- but the more I focused on pushing off using my big toe instead of middle toes, the better it got.  And in the last 1/2 mile, it did start to hurt a bit -- but again, I focused on pushing off my big toe and the pain became more manageable.  I didnt expect or get a miracle cure, but it was definitely encouraging.

According to Wendi,  Dr Dudley Morton (I'm guessing this is where the "Morton" of "Morton's Neuroma" came from) solved for the problem by using a pad the size of a stick of gum under the big toe, and people were actually healed from the issue.  But after he died, orthotics came along -- but these are only temporary fixes and dont heal the problem, like the pad under the big toe does.  She also says metatarsal pads can help manage the pain, but that's all ... it does not heal the problem.  The inserts are the primary key to healing.

Just an update ... since getting the shoes, Prokinetic inserts and using yoga toes, I've been able to do my long runs with very little issues at all. I have an occasional flash of numbness -- but only lasts a minute or so at most. No pain at all.  And this was all with a full blown, fully podiatrist-diagnosed case of Morton's Neuroma in both feet. (I hobbled my last 3 miles of a half marathon in May from it!).

The inserts in particular were quite hard to get used to.  I had a lot of miscellaneous aches and pains in my back and hips, given the inserts essentially changed the way I was carrying myself and running ... but the "shoe whisperer" warned me of this.

Since getting the inserts, shoes, etc -- I've done numerous long runs, including several 14, 16, 18 and 20 milers.  Again, minimal numbness and no pain.

Dear Pete,

I have experienced occasional numbness, pain and swelling in my feet for years and I think I have finally pinpointed the main reason. 

I recently discovered that I have a genetic condition called Morton's Foot and you may have it also (as does 20-25% of the population).  It is a condition where the second metatarsal in the foot is longer than the first (big toe) which causes the weight to be improperly distributed when you walk/stand, leading to pain in the foot, weak ankles, leg, hip, back, neck and head pain.  You can read more about this and also see how to determine if you have inherited it through this link: http://www.triggerpointbook.com/mortons.htm.  It also explains what you can do to ease the condition.  You may find that this explains a lot about why, no matter what we try to do, we have chronic pain and dysfunction in these areas.  If the foundation is weak, the house begins to crumble! 

You can try to create your own corrective pads or insoles or purchase the ProKinetic Natural Body Balance ones from www.mortonsfoot.com.  Their website also has a lot of information about various conditions relating to the feet and legs, their causes and solutions. 

I first learned about Morton's Foot in the Trigger Point Therapy Workbook, which I highly recommend, as it illustrates all points on the body that can be massaged to relieve localized and referred pain.  Trigger points in the muscles of your feet and calves, activated by overwork or undue stress from misalignment, could also be a factor in the onset of numbnes in your feet that you have experienced.  The workbook is available at Amazon for $14.97.  A lot of information is also available online through the above link (see their side menu).

Best Wishes,

Nia