Transitioning from CrossFit to marathon training

Last year, I decided to pursue a long time goal of mine: running the New York City Marathon. In preparation for the 2023 race, I've gradually exchanged my 5 weekly CrossFit workouts for long, easy runs with a bit of strength training sprinkled in.

Since I'm currently in the thick of a training block, I want to take the opportunity to share the biggest lessons I have learned along the way. While running is my modality of choice this year, the following concepts should be relevant for making the shift to any form of endurance training.

Don't exceed your maximum recoverable volume

For many reasons, it is critical to ramp up slowly when starting any new training program. Even though aerobic work may seem easier and may not make you as sore as lifting does, your body still needs lots of time to adjust to a new training stimulus.

A rule of thumb in the running world is not to increase total mileage by more than 10% each week as you increase the length and frequency of your runs. Similarly, the length of your longest individual run should not increase by more than 10% either compared to the previous week.

An additional consideration for strength athletes is that running plans were not necessarily designed to be performed on top of your previous exercise routine. That's not to say that you need to drop all your other workouts overnight, but prepare to reduce them significantly if you're serious about your running goal.

The total training load that you can tolerate depends on your background and your current level of fitness. Just to throw an example out there, this is how I personally scaled down my CrossFit training as I scaled up my weekly running mileage:

0 - 10 miles/week  →  5 CrossFit sessions/week
10 - 20 miles/week  →  4 CrossFit sessions/week
20 - 30 miles/week  →  Gradual transition from CrossFit to pure strength training
30 - 40 miles/week  →  3 strength training sessions/week
40 - 50 miles/week  →  2 strength training sessions/week

Although your body does adapt to a higher volume of training with time, there comes a point of diminishing returns where progress begins to taper off. For me, that point came at around 25 miles per week. I found that the combined cardiovascular load from running and CrossFit became too much for my body at that time. Since my ability to recover had declined, my progress slowed down as well.

As a result, I decided to switch gears and eliminate any cardiovascular exercise that was not running-specific. Swapping CrossFit for bodybuilding-style strength workouts (and limiting their intensity and frequency) has worked well for me, but your mileage may vary.

Intra-workout fueling is key for long sessions

If you've never had to eat during a workout before, developing a strategy for intra-workout fueling can be quite a challenge. After about 90 minutes of moderate intensity activity, your body's stored energy (glycogen) gets depleted, so you will need to eat something on the go in order to sustain your output.

Most runners prefer taking in fast digesting carbohydrates in forms of gels or chews. As a general guideline, it's recommended to consume about 100 calories for every 30-45 minutes of activity. However, everyone's GI tract responds differently here, so it may take some trial and error to determine the timing that works best for you.

Another crucial element of the intra-workout fueling is hydration. You will likely need to replenish your fluids and electrolytes during longer efforts. The optimal dose and frequency for you depends on outdoor conditions such as temperature, elevation, and humidity, as well as the amount of salt and water you personally lose as sweat. In a similar vein as carbohydrate intake, it's important to adjust your hydration strategy based on how you respond as an individual.

Go slower to go faster

CrossFit athletes will understand that it can be often be harder to hold back than to push yourself to the max. As opposed to most metcons which require all-out effort for 10 to 20 minutes, endurance events test your ability to maintain a consistent pace over several hours. Thus, training for endurance requires a dramatically different approach than training for maximal power output.

While it may be counterintuitive at first, performing most of your runs slower than you think you should is the key to getting faster with time. Many of the top running coaches believe that it's optimal to keep 80% of your runs at a conversational pace (i.e. you are breathing easy and can hold a conversation while running). This pace puts your body the best position to improve its ability to utilize oxygen and fat for energy. It also greatly reduces the risk of injury, which keeps you in the game as your training sessions get longer.

Keep strength training in the picture

Although I just recommended scaling back on strength training to maximize recovery, strength is still a vital component for runners who want to stay healthy and maintain their competitive edge.

The number one reason to continue lifting while on a running program is that it improves your movement quality and decreases your risk of injury. When you limit yourself to only running, you're committing to the same repetitive movement pattern and this can exaggerate small muscular imbalances you have over time. Incorporating a variety of exercises in the weight room does a lot to strengthen and activate muscles that are weaker and balance out your running form.

Furthermore, strength training can improve your running efficiency by making your muscles stiffer. A stiff leg muscle can store more energy and thus requires less effort to shorten and propel you forward after you hit the ground. You can see this clearly by comparing a thick rubber band to a thin and flimsy one. It is harder to stretch out the thick band, but it unleashes a lot more force than the thin one when you let go.

Focus on the positives and enjoy the process

Since I started training like a runner, there have been many moments when I've missed my former CrossFit routine. On some mornings, I catch myself mourning the muscle mass that I have lost by trading reps for miles. On other days, I have started 2 hour runs only to have my earbuds die 10 minutes in. Left to face the tyranny of silence and my own thoughts, I questioned why I had signed up for this.

Luckily, there have been many positives in my running journey that outweigh the negatives. For instance, my stress level has gone way down since I lowered the intensity of my training. Furthermore, the many hours I've spent on the road have given me time and space to process my thoughts and find mental clarity.

At the end of the day, I believe that challenging yourself physically in different ways is almost always worth it. While my muscles may grow and shrink during different seasons of my life, the satisfaction and wisdom that come with conquering a new goal last forever.