Do’s and Don’ts of Building Leg Strength in Runners

Marc Lindsay
by Marc Lindsay
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Do’s and Don’ts of Building Leg Strength in Runners

Whether you’re a new runner or an experienced marathoner, it’s common to feel like the pain and discomfort in your legs is what’s holding you back. While you can definitely expect to fatigue as the distance increases, there are ways you can mitigate this dead feeling in your legs to run longer distances and get faster.

Recently we got together with Angela Tieri, a coach at McMillan Running and founder of the Marathon Legs training program, to get her advice on the do’s and don’ts for building the leg strength necessary to run farther while staying injury-free.

It makes sense that if you want to run farther distances, you’ll need to up your weekly mileage. Unfortunately, conditioning your legs to handle the stress of longer distances is more complicated. Because, while cardiovascular fitness can normally be developed quickly, your physical body can take months, if not years, to get used to the strain of higher mileage.

“It takes the body’s muscles and tendons much longer to adapt to the load of training than it does for the cardiovascular system,” Tieri says. “Runners will feel really fit and ready to run fast, but their body isn’t quite ready to handle that stress yet. I see this challenge most often in newer runners who unfortunately end up getting injured. It’s the classic case of too much too soon.”

One common strategy for many ultrarunners looking to step up to the 50-mile or beyond distance is to link up back-to-back long runs to simulate that tired and fatigued feeling in the legs that’s common in longer running events. While this strategy may be valuable for experienced runners and help develop the necessary mental toughness needed for longer events, Tieri cautions against this approach for most runners.

“Doing workouts on tired legs can be counterproductive, as you either won’t be able to hit the correct paces or you’ll have to work too hard to hit your targets. Form can get sloppy under intense fatigue, and that can lead to compensation and injury, so it’s best to avoid running when you can’t maintain proper form,” Tieri says.

When you’re training to run longer, being patient and building your weekly mileage slowly is key. This allows your body to adapt gradually and prevents overuse injuries from popping up and derailing your training plan. According to Tieri, this involves mostly long, slow, distance mileage that doesn’t focus on building speed.

“The first step in training for a marathon or ultramarathon is to slowly build up a solid foundation of base miles. Focus on stacking successful week on successful week, and over time the body will adapt to the challenge of running farther,” Tieri says. “Runners can start this base-building up to 24 weeks before their goal race. Intense track workouts often aren’t necessary, especially in the first few months of training, as the goal is on increasing endurance, not speed. Speed will naturally increase as the runner gets more aerobically fit.”

While mental training might not seem like it has anything to do with conditioning your legs, building base mileage first can help you become acquainted with what it takes mentally to move past common discomfort. Believe it or not, the less you focus on the bad parts of going longer, the more you’ll enjoy long runs and learn to be comfortable with less than ideal circumstances.

“Getting accustomed to the focus required to run for hours is very important for having a successful marathon or ultra,” Tieri says. “Learning that you can keep running, even when you want nothing more than to quit, is a very valuable experience that runners can call upon on race day when they inevitably get to that moment when they want to stop.”

Once you’ve built up base mileage and have become more comfortable with the mental aspects of going longer, you’ll be able to move on to the next phase of your training plan.

Even though running gets your legs stronger — particularly your quads and calves — you’ll still need to incorporate strength training into your routine to condition your legs to tackle longer distances. This becomes more important as you start to tire in the latter stages of a race or training run. If you have the necessary strength it will help you get through those tough miles. One way Tieri incorporates strength training is to combine sessions with a weekly long run.

“Using strength training to simulate fatigue and heavy legs is a tool I sometimes use with athletes training for longer races who can’t handle lots of mileage,” Tieri says. “I have them complete a longer strength session the day before or a shorter session the same day as their run. Their legs often feel “heavy” in the first few miles but by the end of the run, their legs feel full of pop. But again, these are only used with long runs or easy runs and not (more intense) workouts.”

Tieri also recommends runners start with bodyweight exercises that focus on eccentric loading to build strength during the lengthening phase. This can help to strengthen connective tissue instead of only focusing on the muscle.

“When starting out a strength-training program, focus on nailing proper form on all the fundamental movements without weight. Then, just like with running, slowly add load and intensity over time,” Tieri says. “[It’s important] to select a strengthening program that progressively loads runners’ legs in a way that won’t detract from their running and helps to avoid potential injury.”

An ideal strength-training program focuses on your weaknesses and corrects imbalances, whether it’s the hamstrings, glute medius or the core. For that reason, there’s no set exercise routine that works for all runners, making the need for individualized coaching an important choice for anyone who is serious about longer distances.

Whether you want to run your first mile or set a PR, having a plan gets you there faster. Go to the MapMyRun app, tap “Training Plans” and set your next goal — you’ll get a schedule and coaching tips to help you crush it. 

About the Author

Marc Lindsay
Marc Lindsay

Marc is a freelance writer based in Scottsdale, Arizona. He holds a master’s degree in writing from Portland State University and is a certified physical therapy assistant. An avid cyclist and runner of over 20 years, Marc contributes to LAVA, Competitor and Phoenix Outdoor magazines. He is the former cycling editor for


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