9 Reasons Why CrossFit and Running Are The Perfect Training Partners

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In this post, Amy Knutsen Whitson, M.D. talks through her experiences combining CrossFit and running:

Have you ever wondered how much and what type of strength training to work into your running life?

I am a lifelong athlete and a working mom training for my first marathon.

Like many of you, as the mileage increases, my training runs take longer, and it becomes more challenging to find time to train. 

At any point in the day, my runs are a necessary time and space for renewing my body, mind, and soul, so how does strength training fit in? 

I find CrossFit training sessions create the balance I need to keep running consistently and successfully. 

Mention CrossFit to a group of runners and you’ll usually be met with indifference, or comments about getting injured – but done correctly, CrossFit can be blended with your run training to make you a much more effective runner.

Here are nine points about how CrossFit can be the ultimate cross-training activity for runners of all backgrounds!


Let’s jump in!

crossfit and running

#1: CrossFit is For All Athletes

Long runs are the cornerstone of marathon training.

A great way to maintain strength and endurance is to incorporate a high-intensity interval training (HIIT) program like CrossFit into your routine. 

CrossFit is available to athletes at all levels, and an excellent addition to any endurance running program. 

It is remarkable to watch people of all ages working as a team in CrossFit classes.

They modify their workouts to accommodate individual athletic needs. I found CrossFit training sessions modifiable, accessible and FUN, even in my mid-forties! 

I was particularly inspired by my trainer’s parents who are in their 60s dominating their workout, maintaining their own level of health and fitness while working alongside much younger athletes. 

Everyone was working hard together but in their own way and having fun!

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#2: Injury Prevention – A Key to Runners’ Longevity

As we age, and the longer we ask our muscles, bones, and joints to support us there is an increased risk of injury due to wear and tear.

The best way to prevent injury is to maintain a strong core and large muscle groups

Due to hormonal changes, our muscle and bone mass decrease as we age, and this natural tissue loss can lead to injury unless maintained.

I suspect each of us seeks the perfect balance and combination of training activities to support our running habit.

My magic combination is CrossFit, yoga, stretching, and meditation, woven into the fabric of my monthly training goals. Each can improve a runner’s workouts in unique and complementary ways.

CrossFit is an excellent whole-body strength training program that keeps our runs stable and strong.

Related: How Stretching Is Sabotaging Your Running – Avoid These 5 Harmful Stretching Exercises

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#3: Does CrossFit Lead to Injury? It Shouldn’t

I must admit, I was a little intimidated at first, and warned by several people to avoid CrossFit if I didn’t want to get injured.

After consulting with a certified CrossFit coach and learning more about the philosophy, I gave it a try. 

The Workout of the Day (affectionately known as the WOD) is a whole-body combination of basic strength and cardiovascular movements that are modifiable for each individual’s level of fitness.

Even people rehabilitating from injury can perform modified movements and work on balance and flexibility to help hasten recovery. 

After overcoming the soreness that ensues from working new and different muscle groups, I found that my running form, endurance, effort, and mental focus all improved after adding CrossFit to my training routine.

crossfit and running

#4: A Brief History of CrossFit

CrossFit was established in 2000 by former gymnast Greg Glassman. According to The Box, there are ten key elements athletes are improving upon in CrossFit workouts: 

  • strength/stamina
  • balance/flexibility
  • speed/power
  • agility/coordination
  • accuracy 

These are elements that we as runners are improving with during every training/endurance run, just in a different way from the CrossFit training sessions.

And as we age, we may need to focus on a particular facet, such as flexibility, coordination, or balance. 

crossfit and running

#5: Anatomy of Strength Building

The basic anatomy and physiology of weight training and endurance training are simple when described in terms of short and fast-twitch muscle fibers. 

  • Red, Type I, or slow-twitch muscle fibers, are fatigue resistant and focused on sustained small movements and posture or proprioception as we move.

    They have a robust blood supply, hence the “red” appearance and contain more mitochondria, the powerhouse of our cells, and myoglobin, compared to white, or fast twitch fibers.

    Red muscle fibers are our endurance fibers and sustain us as we move for long periods of time. 
  • White muscle fibers, Type II, or fast-twitch muscle fibers give us bursts of activity and fatigue quickly.

    They have a small blood supply, hence the “white” appearance and early fatigue.  

Athletes engage BOTH types of muscle fibers because both are found in ALL skeletal muscle (the muscles we use voluntarily), but the amounts differ in different parts of the body.

Activities requiring high intensity and short duration, like CrossFit, build up our supply of white muscle fibers while endurance activities such as distance running increase red muscle fibers. 

Activities such as CrossFit when sustained can also allow the fast-twitch fibers to recruit slow-twitch fibers which improve overall aerobic power.

A well-conditioned, lifelong athlete is best served by optimizing both types of fibers, which is another reason cross-training is so important. 

Related: 6 Downsides of ONLY Running: Why Runners Need To Cross Train

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#6: How Much Strength Training Is Enough?

Have you ever found yourself wondering, “how much strength training should I add to my running routines?”

Well, the answer varies from person to person but is generally “more than you think you should”, and more as you age. 

Consider Karly Wilson, the 32-year-old marathon runner, and CrossFit athlete. 

According to a 2017 article in the CrossFit Journal, Karly runs a marathon a month, and in her late 20s added strength training to decrease her marathon time and increase her endurance.

Her magic combination is a morning CrossFit workout, then an evening lower body workout or run. After incorporating CrossFit, her form and endurance improved, and she qualified for the 2018 Boston Marathon below the qualifying time for her age group. 

Each run is different, unique, and perceived success and running mood depend on my ability to focus.

The amount of strength training you need depends on your age and overall fitness level. I usually don’t have time for two-a-day training sessions, so I currently alternate a run day with a strength day, with one day a week off, for recovery.

Consider starting your strength routine with 1-2 days a week and increase as you build strength and ability. 

crossfit and running

#7: CrossFit is Efficient

Now, not all of us have four hours a day to devote to training.

One of the beautiful aspects of CrossFit is the efficiency of the workouts. 

A typical CrossFit WOD is a 10-minute warm up, 15-20 minutes of high-intensity cardio and strength work, and a 5-10-minute stretching and cool down.

CrossFit sessions are typically held in spaces called “boxes”, which are small contained spaces with a limited amount of equipment for isometric and cardio work. 

I can be in and out of the “box” (CrossFit sessions are often held in small spaces called boxes) in 30 minutes and feel as though I’ve just conquered 2 hours of a hard run. 

And each WOD is different, so you are always engaged and learning something new with every session! Another secret to longevity: life-long learning.

With CrossFit you are working harder, and smarter!

crossfit and running

#8: Strength Training for Runners, It’s Not All About the Legs!

There is something empowering and energizing about being able to settle into a run, then find yourself conquering the elements without feeling drained.

When your legs are gassed on a hill, your arm swing picks up the pace and will pull you through. 

Many CrossFit sessions focus on core and upper body muscle groups by working on pull-ups, kettlebell swings, push-ups, overhead presses and burpees (how we love the burpees!). 

All of these moves strengthen your shoulders, back, and arms which when fully engaged will pull you up those mountains!

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#9: How to Add CrossFit to Your Running Routine

Running is a total body, energizing, lifelong labor of love.

CrossFit requires mental toughness, which is business as usual for runners, and the training is widely available in all places and for all people, in most places around the world all days of the week and on weekends. 

Consider these tips:

  • Try a CrossFit workout before your run, on a low mileage day.
  • Tell your CrossFit coach that you are supplementing your running routine with CrossFit training.
  • Incorporate CrossFit on a Saturday or Sunday, opposite your long-run day.
  • Start with 1-2 classes per week, and add as you feel more comfortable and gain strength.
  • Make sure to incorporate stretching after CrossFit training.

So, if you’re wondering about adding or changing up your training routine consider trying a CrossFit session or two and watch your focus and your miles increase.

Photo of author
I am a native Texan, born to run, enjoy and live life outdoors. My medical career has allowed me to live in Philadelphia, Boston, San Antonio, Minneapolis, and now Columbus Ohio. I am trained as a general surgeon, have practiced acute care, trauma, burn, and general surgery. I've traveled and found running groups throughout Europe and Singapore. My favorite sports are whatever my kids are playing. I run to feel great! Favorite running companion is CrossFit, favorite hobbies are cooking and travel! Goal: Can't wait to run my first International Marathon!

2 thoughts on “9 Reasons Why CrossFit and Running Are The Perfect Training Partners”

  1. CrossFit is fun. Staying safe and achieving your fitness goals is important, but you can actually improve both of those elements with a training partner.

    This blog addresses some reasons why Crossfit and running are great training partners, which is likely unknown to many of us. But they should be considered. The information you shared with us seems useful, so thank you for sharing it.


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