It is often a struggle to find a balance between training for a marathon and the rest of your life's demands. Work and/or weather constraints can often lead runners to train on treadmills.
Running on the treadmill is not quite the same thing as running outside. The treadmill is easier since the belt assists your legs in moving forward and in turnover. The surface of the treadmill is also softer than that of outdoor surfaces, so your body doesn't have a chance to get accustomed to the running on harder surfaces.
I would reserve treadmill running for shorter distances during the week or for speed work. Speed work on the treadmill is great since you have to keep up with the pace of the belt. Many runners use the various programs on the treadmill for a challenging indoor workout, and you have no choice but to keep up with the changing speeds or inclines.
For your long runs leading up to the marathon, I would advise you to head outside. That way, you’ll get accustomed to the harder surfaces and the weather, and you can practice your fueling strategies. Another suggestion, since you mentioned that you can only train at night, is to find a local running club. Many clubs run in the evening, and perhaps you can find one that works with your schedule.
If you’re really limited to the treadmill, I would advise running on a 1-percent to 2-percent incline, trying to maintain your long run pace, and changing the incline to simulate the hills that you will encounter during the marathon.
Whether you run outdoors or on the treadmill, remember to stay hydrated and well fueled for your training.
Julie Khan is a physical therapist in the HSS Rehab Department. Julie graduated from Columbia University with a Masters and a Doctorate of Physical Therapy. Her clinical interests include post-surgical sports-related injuries and running mechanics. Julie is a runner and has completed more than 20 half marathons and five marathons; she is currently training for her sixth, which will be the ING New York City Marathon this fall.