Since this is a running forum, I thought I'd ask a running question since y'all are such sages:

I just retired a pair of Brooks Defyance 5 shoes (my 2nd pair) after about 700 miles.  Was fighting some PF and a bit of peroneal tendonitis so I switched into my back up pair of Brooks Glycerin 10's.  The latter is a fully cushioned neutral trainer that has about 250 miles on them.  My foot feels better and seems to recover faster in the Glycerins, so I am guessing that the Defyance's were probably worn out.  (I am cheap and try to stretch out my shoes as much as possible).

Anyway, this change in shoe had me looking at the 'house and some of their liquidation offerings and raised this thought to me.  The Glycerin's are considered a "heavy" shoe at 12.2oz per pair with a 10mm drop.  I often read about you guys with racing shoes and I read about how folks feel with lighter shoes.  Since I am only 3 pairs of shoes into my running life, and of them only 2 different styles, I am a noob when it comes to things like shoe weight.  Questions:

1. How much does a shoe weight affect a marathon performance?

2. Does a shoe weight impact your daily training runs?

3. Will a lighter shoe create a greater chance of injury such as PF or tendonitis?

4. For a newer runner (under 3 years) does shoe weight really matter?

I think shoe weight does play a part but not necessarily a big part in performance on race day.  Having said that, you have heard us talk about racers and that's all they are, for race day.  I personally do not train a lot in my racing shoe.  I do a couple of specific workouts if the shoe is relatively unknown on that distance, but I train in heavier shoes that I run.  Why?  To minimize injury and get more support to the foot throughout training (and less tired during marathon training).  And the difference in how the legs feel on race day is great.  I am running with less weight on my feet and after training, the racers feel like they are flying!

Not sure if this is scientifically proven, though.  Just my experience.

Of course this is my opinion:

1. Check out that link Kevin posted.

2. Yes, but it is dependent on the runner. I train in a 10oz shoe. It feels normal. If I go to a 12oz I feel like weights are on my feet.  If I go to my racing flats, 7oz, I feel super fast.  "However" - I my form breaks down faster in the flats.

3. See above: as form breaks down risk goes up. Depending on conditioning, body/ foot specifics, recovery ability etc. a runner may or may not be able to train in lighter shoes. Or may not be able to run/race in a lighter shoe at all!

4. Psychologically , yes. Feeling fast means a lot.  However in the grand scheme of things feeling better all race trumps the marginal gain you *could* get.

On a personal and related note:

I *want* to race my marathon in my racing flats, however I am concerned that they are not enough shoe for me for 26 miles. The next two months will help me decide.  If I race in my trainers, no big deal.

1. How much does a shoe weight affect a marathon performance?

2. Does a shoe weight impact your daily training runs?

3. Will a lighter shoe create a greater chance of injury such as PF or tendonitis?

4. For a newer runner (under 3 years) does shoe weight really matter?

Nice link.

Full disclosure; I am not qualified on this subject in any way, shape or form (and in other news, water is wet) however, I would like to speak about my experience with training/racing shoes and shoe weight.

After spending the entire year running easy in roughly 9 ounce shoes and racing and doing intervals/tempo runs in 8 and sub-7 ounce shoes for 5 and 10k training, I have found for MRT they simply do not cut the mustard.

So to answer question 2 yes, shoe weight does impact my training depending on what race distance I am training for.  I have found that a return to my big ass Kayanos (11 ounces plus) for long and easy runs has been just what the doctor ordered in terms of cushioning as it relates to the higher mileage and longer long runs.

I generally race in Kinvaras, and wore them for my last HM (plus warmup) with no issues.  So now I am trying to decide- do I run my marathon in my Kinvaras, since they're lighter and they are my "racing shoe," or would the extra cushion and support for form breakdown in the later miles make up for the extra 2 oz. that I'd be lugging around?

FWIW, I ran my last marathon in my Virattas even though they hurt my feet. I'd race in your Kinvaras. It's only 1 run.