When Should I Worry About...

How to Avoid Undertraining for a Marathon

Dec. 18, 2019 - Katie McCallum

Training for a marathon or half-marathon takes dedication. Without it, you run the risk of beginning the race undertrained and underprepared. But, when it comes to training, you may have some questions.

How early should I start training? How often do I need to train? Am I undertraining?

“The best way to train for a marathon is to start early, take it slow and be consistent,” says Dawn Stuckey, athletic trainer at Houston Methodist. “If you try to run a marathon while undertrained, your risk of injury, such as stress fractures and muscle strain, increases.”

Whether this is your first marathon or you’re a few races in but always feel underprepared, consider Stuckey’s tips for avoiding being undertrained.

Be realistic about your fitness level, timeline and goals

The key a successful race is to know your fitness level and give yourself plenty of time to get in shape for the race. Stuckey recommends beginning training about 4 months before a half-marathon and 6 months before a full marathon.

“If you start training early, it means you don’t have to get in a hurry,” explains Stuckey. “You can gradually increase your mileage, building stamina and endurance — without being forced to fit a long run in every single weekend.”

If you’re new to racing, Stuckey recommends setting yourself up for success by choosing a beginner’s race.

“Pick an obtainable race distance to start off with, like a 5K fun run,” says Stuckey. “The smartest way to train for a marathon is to build up over time.”

If your marathon is fast-approaching and you think you’re already behind, consider adjusting your approach to the race.

“Everyone is different, but if you’re a month out from your marathon and you haven’t run more than 5 or 6 miles, you should probably consider switching to a half-marathon,” Stuckey recommends. “Running a marathon while undertrained increases your risk of injury.”

Find a training plan (and stick to it)

There are tons of elaborate training plans you can find online, but Stuckey recommends keeping your training plan as simple as possible. Here is the basic formula for a great weekly training plan:

  • Run three or four days a week. Focus on a speed workout one day, a long run another day and keep your runs for less than an hour for the remaining two days
  • Plan a longer run once per weekend, gradually increasing your distance
  • Cross-train (swimming, cycling or elliptical) two days a week, on non-running days
  • Rest for one day every week
  • Incorporate core strengthening and stretching into your plan to promote flexibility and stabilization

During your training runs, Stuckey recommends running at a casual pace and taking regular walking breaks. She also recommends developing a warm-up and cool-down routine of jogging and stretching.

“For example, start by jogging at a slower-than-normal pace for about 10 minutes, then stop and stretch for 5 to 10 minutes — then begin your run,” explains Stuckey. “Finish your training session with some dynamic stretching, and think positive thoughts about your workout.”

And, don’t forget to refuel after your run. Chocolate milk, which is high in protein, is a great post-workout snack. You should also follow your run with a well-balanced meal that contains a lot of protein.

Tips for staying on track with your training

Even with a good plan, it can be tough to stay consistent throughout your months of training. Here are Stuckey’s tips for maintaining your training program all the way up to race day.

  • Train virtually with a friend. As soon as you feel yourself starting to slide off the training bandwagon, find a friend who can help you keep up with your running schedule virtually.
  • Take a break and walk. Don’t be afraid to try the run/walk method. Allow yourself 1 to 3 minutes of walking (even when you’re not tired) and consistently follow this for the entire training run. Not only can intermittent walking serve as a mental break, allowing you to refocus, it’s proven to improve overall running time.
  • Change your route. Enjoy your runs by trying different routes that are stimulating and enjoyable.
  • Shoes matter. Selecting the correct pair of running shoes is critical for injury-free training.


Above all, Stuckey recommends that you know your starting fitness level and stay realistic about your training and race goals in the time frame you have.

“Some people can get in racing shape in just two months if they’ve already been running. But, if you’re starting from couch to 5K and try to rush your training, you could hurt yourself,” says Stuckey. “Plus, the stress of trying to get in shape that month may also affect you.”

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