Marathon Training Guide

Whether you have questions about how much to run, how to recover, or what pace to run your race at, you've come to the right place. To make your training even easier, our expert coaches have designed free marathon training plans available at the bottom of this guide.

How to Build Running Volume

Marathon training is all about building endurance without breaking down. One simple rule: Increase mileage by 10% per week, and keep your long run under 30% of total weekly volume to reduce injury risk. Start with where you are, work backward from race day, and give yourself 8-20 weeks to build. If you’re running 20 miles per week now, aim for 22 next week, with a long run no more than 7 miles. Small, incremental progress adds up to big race-day results.

COROS Education: The Training Status metric is an easy tool to monitor if you are training the right amount. Athletes should aim to keep their Training Status in the "Optimized" category while building their volume.

Track Your Changes in Fitness

Every run you perform impacts your progress, but not all runs are created equal. Some place higher stress on your body than others, and tracking that stress is the key to unlocking progress. Once you can measure it, you can improve it.

Within the COROS App, you have access to a trendline called "Base Fitness". The higher the score, the more stress your body can handle. During your marathon training, it is important to see improvement and ensure your training is actually working.

An example of the Base Fitness metric increasing over time

COROS Education: Base Fitness is a rolling average of your daily Training Load. With every run you complete, training load measures the stress on your body. When your Base Fitness is improving, and recovery is being monitored, you are in a great spot to excel in your training.

Monitor Your Recovery

Training breaks you down—recovery builds you up. Every hard effort needs proper recovery to make you stronger. Ignore it, and you risk injury or stagnation.

A simple approach is to train hard for 3-4 weeks, then scale back for a recovery week. However, with COROS recovery metrics, you don’t have to guess. Tracking these metrics will help you know when to push and when to rest—so you can train smarter and avoid burnout.

COROS Education: Heart Rate Variability (HRV) and Resting Heart Rate (RHR) are key indicators of recovery. A declining HRV or an increasing RHR can signal that your body needs more rest. Read more on all of our recovery metrics

Plan Your Race Pace

The surge of adrenaline at the start makes it easy to go out too fast, but smart pacing ensures you finish strong. Relying on feel can be difficult, so COROS has developed features to stay locked into your goal pace.

COROS Race Predictor:
Your watch learns from every run, refining your predicted finishing times as you train. The more you improve, the faster your marathon projection becomes.

COROS Virtual Pacer:
On race day, set yourself up for success. Before hitting start, scroll to “Pacer,” select “Marathon,” and enter your goal time. Your watch will then provide real-time pace alerts, keeping you steady from the first mile to the last—helping you avoid early mistakes and maximize your potential.

COROS Training Plans to Help

Now that you understand how to train effectively, having a structured plan can help you execute with confidence. To better help athletes of all abilities, COROS has created a number of free marathon training plans.

Once you've found the right plan for you, sync it to your COROS watch for a step-by-step guide on every run along the way.

Beginner Plans

20-Week Beginner Marathon Plan

16-Week Beginner Marathon Training Plan

Intermediate Plans

20-Week Intermediate Marathon Plan

16-Week Intermediate Marathon Training Plan

Advanced Plans

16-Week Advanced Marathon Training Plan

20-Week Advanced Marathon Plan

Plans Based on Goal Time

12-Week Marathon Plan (4:00-4:30)

12-Week Marathon Plan (3:15-3:35)

12-Week Marathon Plan (2:45-3:00)

Personalized Marathon Plan

Looking for something more specific? Personalized Marathon Plans with COROS will create a marathon training plan that utilizes your past training data to automatically build a plan to help you reach your goals.

Whether you opt for a personalized plan or a pre-built plan from the COROS Training Library, having a roadmap ensures you are training effectively and efficiently.

Ready to Train? Get the Right Gear

To make the most of your marathon training, equip yourself with the right tools. The COROS PACE series provides accurate tracking and advanced training metrics, while accessories like the COROS Heart Rate Monitor and COROS POD 2 offer precision and accuracy for all of your running needs. Check out the COROS products page to find the perfect gear for your training journey.