BigBoy wrote:
... But it brings me to think, does weight honestly matter? Or would you think it would be more concentrated on true fat loss? Since you see all these pro's looking thin as can be. Interesting to think about... any thoughts?
I've run similar times in college (30 years ago). I've since run 36 marathons, and realized that there are 2 factors that influence my marathon times: (1) weight, (2) weekly mileage:
At 173 lbs and 70 mpw, I can run a 3:05 marathon (185 mins). But at 188 lbs (15 lbs heavier) and 36.7 mpw (33.3 mpw less), I only managed to run a 3:40 marathon (220 mins). I think the extra 15 lbs slowed me down by 13 mins (2sec/mile or 0.867). The 33 mpw less, slowed me down the other 22 minutes (.667 min/mpw). So the formula for me is:
PRnew = PRold +0.867*(wt gain) - 0.667(mpw gain)
PRnew =185 +0.867*(15) - 0.667(-33)
PRnew =185 +13 + 22 = 205 mins = 3:40
I'm sure the above formula breaks down if you get your BMI below 20, which is where most elite marathon runners are. There are also some diminishing returns on increasing mileage above 70 mpw, which the formula does not take into account. However, using this formula for a modest weight and mileage change, assume that you can lose 11 lbs and get your weight to 179 lbs (a similar BMI to Chris Solinsky) and bump your mpw up by 5, you may be able to improve on your 2:41 marathon (161 mins) to a 2:28 marathon (148 mins) as follows:
PRnew = PRold +0.867*(wt gain) - 0.667(mpw gain)
PRnew = 161 +0.867*(-11) - 0.667(5) = 148 mins = 2:28
Thus, weight matters if your BMI is above 20.
Weekly mileage also matters most if your mpw is less than 70.