In the first Week 1 post, we talked about setting your paces. Now let’s talk about building your mileage without wrecking your body, your career, or your social life.
At some point in this training cycle, you will hit peak mileage, usually 5, 4, 3, and sometimes even 2 weeks before race day. That peak might be as modest as 40 miles per week or as wild as 100. My biggest weeks have been in the 90s, and while it made me feel like a Kenyan Olympian for about five minutes, I still had to pay the bills, take calls, and answer emails. In other words, you are not a full-time runner. So the goal is to build mileage strategically while keeping the rest of your life intact.
The Two Types of Endurance You Need
Marathoners need two kinds of endurance:
1. Cardiovascular Endurance – Your heart, lungs, and blood vessels working in perfect harmony to pump oxygen to your muscles. This is where things like VO₂ max and lactate threshold live. Higher cardio fitness = faster pace without feeling like you’re dying.
2. Leg Endurance – The ability of your legs to keep moving for hours without mutiny. This is about your muscles, tendons, and joints tolerating the pounding over 26.2 miles.
Here’s the key: both easy runs and fast runs build leg endurance. If you run for an hour, it’s still an hour on your feet whether you covered 8 miles or 6.5. The faster run improves your cardio more, but both build the resilience your legs will need late in the race.
And this is why I believe there’s no such thing as garbage miles. Slow miles still count. In fact, they’re the safest way to increase your mileage without flirting with injury.
How to Ramp Without Breaking Yourself
The most widely accepted rule in endurance training: increase weekly mileage by no more than 10 to 20 percent for 2 to 3 consecutive weeks, then take a cutback week where you run about 10 percent less than the previous week.
Why? Because your body is essentially remodeling itself during training. Muscles adapt faster than tendons and ligaments, which is why runners who skip the cutback weeks often wind up with overuse injuries. The cutback week is where your body catches up and locks in the gains.
Think of it as three steps forward, one step back, except the “back” step is really a springboard.
Practical Ways to Add Miles
Add one extra mile to your regular runs.
Jog slowly between intervals in a speed session instead of walking.
Run one more day per week.
Let your long run naturally grow by a mile or two each week.
Some runners even double running twice in one day or use run commutes to pad mileage. I personally never loved run commuting because it requires two showers, a change of clothes, and an extra logistical headache. Plus, I have a life outside of training. If you can make it work, great. If not, there are plenty of other ways.
The Busy Professional’s Takeaway
Mileage builds fitness, but it also eats time. The key is to find your sweet spot, high enough to build both cardio and leg endurance, low enough to keep your boss, your partner, and your sanity happy. Remember: slow miles count, cutback weeks are sacred, and the goal is to arrive at peak weeks feeling strong, not like you’ve been run over by your own training plan.
You are not just building miles, you’re building a base you’ll cash in on race day. Do it right, and you’ll be standing on the start line fit, fresh, and ready to go.