Chicago Marathon 2023 Training Plan

Running a Chicago Marathon Requires More Than Just Miles

I've done Chicago three times now. The course is famously flat and fast, which sounds like a gift until you're on mile 20 in late October and realize that flat means there's nowhere to hide from fatigue. You can't rely on downhills to sneak in recovery. Here's how I'd approach building a solid Chicago Marathon 2023 Training Plan, or any Chicago-focused program, based on what actually works and where people go wrong. The fundamentals haven't changed much since 2023. You still need 16 to 20 weeks depending on your base, you still need long runs that build progressively, and you still need to train your gut before you train your legs. What's different is how much you adjust for Chicago specifically.

Chicago Marathon 2023 Training Plan: The Core Structure

A proper plan has five types of runs, not just "easy" and "hard." The ones people skip are the ones that matter most for Chicago. Easy runs make up about 70 to 80 percent of your weekly mileage. These should be genuinely easy. If you're finishing an easy run and feel like you could have gone farther, you did it right. Most runners do these too aggressively because they're uncomfortable going slow. I've watched people crush their easy days and then blow up on Tuesday's tempo run. It happens constantly. Long runs are your anchor. In a Chicago plan, your top three long runs should be at or near race pace. This isn't theory. Chicago's flatness means you can hold marathon pace for a long time if you've practiced it. Your longest run should be around 20 to 22 miles, typically eight to ten weeks out from race day. After that, you're not building fitness anymore, you're just accumulating fatigue.

Tempo runs are comfortably hard. The standard is about 20 to 40 minutes at marathon pace or slightly faster, sandwiched between warm-up and cool-down. For Chicago specifically, I'd lean toward marathon pace or goal race pace rather than the traditional lactate threshold pace. You're training to hold that even split all day long, not to surge through intervals. Interval work keeps your cardiovascular system sharp without the cumulative toll of long runs. Things like 6 by 1 mile at 5K pace or 10 by 800 meters are standard. Two interval sessions per week is usually the ceiling before recovery suffers. Some quality plans drop interval work entirely in favor of tempo runs in the final four weeks, which is a reasonable approach if you're not a natural track workout person. Recovery runs on your rest days are non-negotiable for most runners. A 30 to 45-minute jog at an easy pace promotes blood flow and speeds up clearance of metabolic waste. Skipping them doesn't hurt—you'll still recover—but including them consistently improves your next hard session's quality.

What Actually Goes Wrong

I learned this the hard way during my second Chicago attempt. I was following a plan that peaked with a 20-mile long run at goal marathon pace eight weeks out, then tapered down. Sound standard. It was. The problem was that I'd spent ten weeks building fitness but never actually ran more than 15 miles at race pace. My body knew how to run 13.1 at that effort but completely shut down past mile 18 because it had zero experience there. I hit the wall at mile 20 and walked the last six. The plan wasn't wrong, but it wasn't specific enough to Chicago's demands. A flat course exposes every weak point in your preparation because there are no hills to relieve the mental pressure. After that, I changed my approach. Any run over 16 miles in the final eight weeks gets run at goal pace or slower. The last three long runs are strictly marathon pace. This means your longest run might feel underwhelming on paper, but by race day your body has already lived through what's coming.

Another thing nobody talks about enough is heat adaptation. Chicago in October can still hit 75 or 80 degrees on race morning. If your training has all been in comfortable 50-degree weather, your pacing will be off by 30 to 60 seconds per mile on race day because your body is working significantly harder at the same speed. I started doing some of my long runs in the summer months, even if it meant dropping the distance slightly. Running a 16-mile long run in 85-degree heat taught me more about pacing and fueling than any perfect 90-degree training day ever could.

Week-by-Week Breakdown

Here's how a typical 18-week plan looks when you strip away the filler and keep only what produces results. Weeks 1 through 4 are your base-building phase. If you already log 25 or more miles per week, you can start here. If you're below 20, add two weeks before moving forward. The goal is to establish a consistent weekly rhythm without injury. Don't increase total mileage by more than 10 percent per week. That guideline exists for a reason, and ignoring it is how people miss the second half of their training plan entirely. Weeks 5 through 8 introduce structured intensity. Add one tempo run per week. Long runs climb from 12 to 16 miles. Keep your easy runs easy. This is where most runners accidentally ramp up the intensity on easy days and accumulate too much fatigue for the hard sessions to actually be productive.

Weeks 9 through 12 are the peak block. Two quality sessions per week. Long runs reach 18 to 22 miles. Mileage hits its highest point. This is also where life starts interfering—work trips, family obligations, minor injuries. Plans that account for this build in one or two "flex" weeks where you can recover without derailing the entire progression. If you miss a workout, don't try to make it up. Just continue with the next scheduled session. Weeks 13 through 16 begin the taper. Mileage drops by roughly 20 to 30 percent each week. You maintain intensity but reduce volume. This is counter-intuitive for most runners because it feels like you're losing fitness. You're not. You're shedding fatigue so the fitness you've built can actually show up on race morning. Weeks 17 and 18 are the final cutback and race week. Your last long run should be around 10 to 12 miles, mostly at easy effort. Race week is about staying loose and preserving energy. Do not try to squeeze in any last fitness work. It won't help and it will cost you.

Things Most Plans Get Wrong About Chicago

First, most plans don't account for the fact that Chicago is so fast that your goal pace feels too easy for the first 10 miles. I've seen this repeatedly at the start. People run the first half a minute per mile faster than goal and then pay for it brutally. The plan needs to include practice at even splits, not just at goal pace. Run a few long runs where the first half is exactly 30 seconds per mile slower than your goal and the second half matches goal pace. It's uncomfortable, and it works. Second, fueling is where races are won or lost on this course. Chicago is flat and fast, which means you burn through glycogen quicker than on a hilly course at the same perceived effort. You need to practice taking in 60 to 90 grams of carbohydrates per hour during your long runs. Most people train at 40 to 50 grams and then hit the wall at mile 18 because their body has never processed more fuel than that during exercise. I carried two gels per hour during my last Chicago and finished strong because my stomach was trained, not just my legs. Third, there's a common misunderstanding about cross-training. Some plans prescribe significant cycling or swimming to supplement running. For Chicago specifically, I'd limit this. The course rewards running-specific endurance, and time spent cycling is time not spent building the specific muscular endurance you need for 26.2 miles on flat pavement. A little cross-training is fine if you're dealing with niggles, but it shouldn't replace running miles in a Chicago plan.

Where This Approach Falls Short

Being honest about limitations matters. This framework works well for runners who can handle 40 to 60 miles per week during peak training. If you're a beginner running less than 20 miles per week, you need a longer buildup phase, and the intensity portions will need to be scaled back significantly. The plan assumes you have a solid aerobic base already. It also assumes you can run in various weather conditions. If you live somewhere with extreme cold or limited safe running surfaces in the fall, your long runs may need to be supplemented with treadmill work, which changes the equation for pacing and fueling practice. Treadmill long runs at marathon pace don't translate 1-to-1 to road racing because there's no wind resistance and the surface is different. For runners who've struggled with injury in the past, the 10-percent mileage rule sometimes isn't enough. I've worked with runners who needed 5-percent increases or even flat weeks for several cycles before they could build safely. There's no shame in slowing the progression if your body is telling you to.

If you're looking for a downloadable version of this plan, the general structure above is something you can adapt into any spreadsheet or training app. I've used Garmin Connect and TrainingPeaks to map it out, and both handle the progression well. The key detail that no app auto-fills for you is the race-pace long runs and the even-splits practice. Make sure those are explicitly scheduled.