When it comes to weekly mileage increases as you train for your next marathon, you can follow the general rule of adding one mile per week for each base run you complete. So if you get in four runs focused on aerobic conditioning, you should be able to increase weekly mileage by four miles. You’ll then need to hold steady at the new mileage for two to three weeks, with a focus on increasing your intensity during the second and third weeks.
Building miles and endurance is an essential part of training, but keep in mind that endlessly adding mileage is not a good aerobic training strategy. Many marathoners follow a “two up, one down” or “three up, one down” approach to adding mileage, dialing back every third or fourth week before adding mileage again. This strategy helps to push your aerobic conditioning while minimizing the risk of fatigue and giving your body a chance to rebuild.
As usual, it’s also a good idea to listen to your body as you decide when to increase mileage and by how much. If you bumped up your miles a few weeks ago, and you’re still feeling a bit sore and tired or having trouble meeting your pace goals, you may want to hold steady for a week or two longer than you originally planned. Also keep an eye on your running form and if it’s starting to break down as your mileage increases, that’s a clear sign that you need to hold steady or even take a step back temporarily. There’s no positive benefit that comes from compromising your technique just to get a few more miles on your odometer.
To help guard against adding mileage too aggressively, some runners add in a cross training regimen focused on building strength and flexibility. Consider adding strength training sessions, which will naturally help your body handle longer distances, and workouts such as yoga or Pilates to stay loose and limber.