Seeking concrete training advice

I'm going to vote for 'coincidence'. The cushion in your shoes evens out the vast majority of the difference between concrete and asphalt.  And cramping is very unlikely to be due to slightly higher impact forces (due to a harder surface) in any case.

If I were you, I'd continue my training for NYC as planned.  You are headed for a great race...

Thanks, guys. I was inclined to write it off as a coincidence, but the road surface difference was so noticeable when I was running yesterday, that it made me reconsider. It's certainly the case that there is a major difference in the hardness of concrete and asphalt (imagine banging a hammer against either material), though I'm not sure how much difference that makes to a runner with well cushioned shoes.

I know that the road surface was an issue for some of the athletes preparing for January's Olympic Trials marathon in Houston, because much of that route was on concrete. The week before the race I was visiting with an old friend who currently works at Nike with a number of the elite runners, and he said that some of the leading athletes were considering ditching their normal racing shoes because of concerns about the concrete beating up their legs.

I think I'll stick with the general plan (adjusted for the week that I lost), but perhaps follow the advice to seek out a couple of opportunities to calm my mind. And I'll continue to aggressively massage my calf, which has helped a lot in recent days.

when I run on hard surfaces I try to focus on my form, to keep my feet low to the ground to minimize unnecessary impact, to keep a mid-foot strike, higher cadence, very light push-off, and even weight distribution.  this combination seems to help with long distance running for me.

Yeah, it's true that the less cushioning your shoes have, the more difference the surface could make.  So elites (or anybody) running in very un-cushioned flats will feel it more than those running in 'normal' running shoes.  Still, I'd vote for coincidence.  (Banging a hammer on the surface is more or less like running without even the cushioning of your own skin and flesh -- i.e., bone on road.)

You are running at a pretty good clip, and that makes a difference too.

I think you are best off making most of your runs on soft surfaces, but the occasional run on a harder surface.  The former will continue to strengthen your soft tissue while allowing it to recover for the next run, while the latter will acclimate you to the hard surface on which you'll be running.  My 2c.

Quick update: the race turned out to be 8 miles of asphalt followed by 5 miles of concrete. I was feeling some calf tightness before hitting the concrete, but within a couple of hundred yards of hitting the concrete I felt the tightening get worse. I managed to stave off full-on cramp until afterwards, but it was a close call.

So now I'm more inclined to take race-pace prep on race-like surfaces more seriously. It seems that the more I do this, the more that I learn that it's all about training to withstand the pounding on the legs.

A lot of the "pounding" aspect of running on concrete can be solved with better running form.  The effects of profound heal striking and over-striding (mid-foot not landing under the center of gravity) will be felt quicker and more severely when running on concrete.

Not an engineer (but did stay at a Holiday Inn Express last night) and asphalt is "softer" than concrete...have you ever driven on a asphalt highway and notice that there are slight indentations in the tire tracks?  Semis and heavy vehicles will actually make grooves in asphalt where as on concrete highways that does not happen.  Granted semis weigh a lot more than the an average runner but it does show that the density and hardness of asphalt is less than concrete.

One foot after the other,

Running Q

And I've heard a marathon runniner / material scientist explain the exact opposite. "For each expert there is an equal and opposite expert".

Yes, asphalt pavement is a bit softer than concrete pavement. It does not matter a whit because your shoes, feet, and legs are far softer by comparison.  Imagine running on soft sand vs. grass vs. rubberized running track vs. hard packed dirt vs. asphalt vs. concrete.  At some point along that hardness spectrum, the surface stops moving under your footstrike, and that point is reached long before the hardness of asphalt.

Asphalt vs. concrete is a myth.

I run on and off concrete regularly and do notice the difference. Not huge, but there was a little something there. At first I didn't think there would be since they're both very hard, but did notice some soreness from the sidewalk sections that went away on the asphalt (or at least didn't increase at times). My stride has much improved over time (more so due to other training things than running on concrete), and it's a non-issue now. I think it really depends on the individual and their stride.

Keep practicing on it. Shouldn't hurt to do it.