When training for a marathon, some long runs go exactly according to plan. (We love those). Some don't. How you handle the ones that don't can have a big impact on how you perform on race day. If you have a sub-par day, there are three ways to handle things:
1 - Go home.
2 - Hold onto your goal pace for as long as possible, but cut the run short.
3 - Go slower than your originally intended pace, but finish the distance.
Option #1 should be exercised if you're sick, injured, or otherwise undermining your long term efforts by continuing to run. It sucks, but fighting it usually just slows your recovery.
But if there's no injury or illness and you're just having a lousy day, you're faced with the choice of hanging on for as long as possible at your goal pace, or slowing the hell down and shuffling through the miles. Far more often than not when an athlete reports back to me that they improvised and changed the workout on their own, they opt to shorten the workout. And far more often than not, I tell them that's the wrong approach. Here's why.
As I mentioned in yesterday's post, my main concern with the long run is "time on your feet". Sure, I'd prefer that it's at the prescribed pace, but for marathoners, there's value even if it's slower. Conceptually it makes sense. On race day if you plan to run a 3:10 marathon and you set out at 7:15/mile but you're a little off your game and come in at 3:20, so be it. You may not get your BQ, but you still get your space blanket and your name in the list of finishers. On the other hand, if you hold your 7:15's until you can't and then walk off the course at mile 20, you'd better hope you have a Metro Card with you.