Marathon runners

The Best Marathon Workout: ‘Alternating Miles’ Long Run

Avoid hitting the wall with this twist to your weekly long run.

Oh, the weekly long run — a staple of pretty much every runner. For those training for half-marathons or longer, long runs serve as the anchor to any sound training plan.

They provide the groundwork for a better cardiovascular system by improving your body’s ability to efficiently deliver and process blood and oxygen to your working muscles. They also help strengthen your soft tissue, muscle, and bones. Combined, these changes make you more apt to handle longer runs at faster paces.

However, a problem arises if you don’t change up your long runs: Your body stops adapting and improvement starts to stagnate. As a career running coach, this is where I see most runners make a mistake. They either try to run their long runs faster each week or keep pushing up the distance — or both in some cases.

While these tactics will force your body back into adaption mode, at some point you’ll hit a point of diminishing returns. Instead of broadly trying to better your previous long run’s pace or distance, try adding some structured pace work.

Marathon Training: Alternating Pace

One of my favorite workouts to spice up the long run for half-marathons up to 50K training is to add alternating pace miles on the tail end of long runs.

By alternating your pace for the later miles — between slightly faster and slightly slower than goal marathon pace — you’re teaching your body to effectively deal with and clear lactic acid while running around marathon pace.

Perhaps an even greater benefit is that, by alternating pace, it’s nearly impossible to get into any type of rhythm. This keeps you on your toes and helps you learn to push through discomfort.

Alternating Pace Running Workout

  • Run three-quarters to half of your long run distance at an easy-to-moderate pace.
  • Then, run the remainder of the long run alternating each mile between 10 to 15 seconds faster than goal marathon, and 15 to 20 seconds slower than marathon pace for the last 4 to 10 miles.

How to Implement in Training

This workout is best done at least twice a month for the 3 months leading up to the marathon. You’ll want to increase the difficulty each time by adding distance on either the front-end easy miles or during the alternating miles. A sample progression may be:

  • Run 6 miles at an easy-to-moderate pace, followed by 6 miles at an alternating pace.
  • Run 8 miles at an easy-to-moderate pace, followed by 6 miles at an alternating pace.
  • Run 6 miles at an easy-to-moderate, followed by 8 miles at an alternating pace.
  • Run 8 miles at an easy-to-moderate pace, followed by 8 miles at an alternating pace.
  • Run 10 miles at an easy-to-moderate pace, followed by 6 miles at an alternating pace.
  • Run 10 miles at an easy-to-moderate pace, followed by 8 miles at an alternating pace.
  • Run 8 miles at an easy-to-moderate pace, followed by 10 miles at an alternating pace.
  • Run 8 miles at an easy-to-moderate pace, followed by 12 miles at an alternating pace.

Don’t Skimp on Recovery

As with any long run, this workout is extremely taxing on the body. Not only does it put a lot of stress on your muscles, but it also depletes carbohydrate stores — the main fuel source for medium- to high-intensity running.

Refueling with a 4:1 carb-to-protein ratio shortly after the run assures your body gets the nutrients it needs to rebuild and recover. My favorite post-long run fuel is Endurox R4. It’s a tasty powder mix that’s easy on the stomach and has a 4:1 carb-to-protein ratio.


Cory Smith is a Santa Barbara, California-based athlete, online running coach, and freelance journalist specializing in running- and climbing-related content and gear reviews. He draws from over 25 years as an elite runner and rock climber for ideas, inspiration, and expertise. Check out his portfolio at www.storiesbycory.com. His work has been featured in Outside Magazine, Trail Runner, GearJunkie, Gear Patrol, Muscle and Fitness, Philadelphia Magazine, and Gear Institute.

Cory Smith
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Cory Smith is a Santa Barbara, California-based athlete, online running coach, and freelance journalist specializing in running- and climbing-related content and gear reviews. He draws from over 25 years as an elite runner and rock climber for ideas, inspiration, and expertise. Check out his portfolio here.

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