If you’re serious about your running and love the challenge of the marathon, it’s tempting to sign up for every race that excites you. The problem? Running too many marathons in a year will cost you your top-end speed.
I see this all the time—runners grinding through back-to-back marathons, wondering why their speed has vanished. It’s not just fatigue. It’s science. If you want to keep your speed sharp while still chasing those marathon finish lines, you need to be strategic. Let’s break it down.
Why Too Many Marathons Slow You Down
1. Marathon Training Builds Endurance, Not Speed
Marathon training is all about aerobic capacity and fatigue resistance. You spend months logging miles at submaximal efforts, training your body to be efficient over long distances. The tradeoff? You’re not training for pure speed. Shorter, high-intensity efforts that recruit fast-twitch muscle fibers take a backseat. Over time, those fibers lose their explosiveness and coordination.
2. Recovery Takes Longer Than You Think
A marathon is not just another long run. It’s a brutal test of endurance that leaves microtears in your muscles, taxes your nervous system, and drains your glycogen stores. Even if you feel fine after a few weeks, deep tissue recovery and neuromuscular recalibration take months. If you’re always bouncing from one marathon cycle to another, your body never gets the reset it needs to regain power and speed.
3. Cumulative Fatigue Blunts Your Ability to Train Fast
Speed work requires fresh legs and a responsive nervous system. If you’re constantly in a state of recovery or training for endurance, your body adapts by prioritizing efficiency over explosiveness. Those track workouts that used to feel smooth start feeling forced. Your turnover slows. You lose the ability to generate and sustain top-end speed.
4. You’re Neglecting Your Fast-Twitch Fibers
Marathon training is a slow-twitch dominant activity. You train your body to rely on slow-burning energy systems, which is great for endurance but terrible for raw speed. Fast-twitch muscle fibers, which are responsible for sprinting and acceleration, atrophy if they aren’t used. If you’re not deliberately training them, you’re losing them.
5. Your Hormones and Nervous System Need a Break
Marathon training places a significant load on your endocrine system, particularly cortisol and other stress hormones. Over time, chronic high training loads can lead to burnout, decreased muscle power, and sluggish neuromuscular responses. This is why elite runners cycle their training, taking time to rebuild their speed and power before ramping up endurance again.
How to Keep Your Speed While Running Marathons
If you love the marathon and don’t want to sacrifice your speed, you need a smarter approach. Here’s how:
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Limit Yourself to Two Marathons Per Year
This gives your body enough time to fully recover and allows you to dedicate part of the year to speed-focused training in between them. -
Build a Speed Block Into Your Training
Take at least 8 to 12 weeks each year to focus on shorter, faster running. Think sprint work, short intervals, and 5K/10K training. This will help maintain your fast-twitch muscle activation. -
Incorporate Strength and Power Training
Heavy lifting, plyometrics, and explosive drills are essential for keeping your legs powerful. This is even more important as we age, since we naturally lose muscle fiber recruitment over time. -
Prioritize Full Recovery Between Marathon Cycles
Give yourself at least 6 to 8 weeks of lower mileage and varied workouts before jumping into another marathon build. Use this time to regain sharpness. -
Work With a Coach Who Understands the Balance
Not every coach gets this. Many will just pile on mileage without considering the long-term tradeoffs. I specialize in helping runners—especially masters and menopausal athletes—find the right mix of endurance and speed.
If you’re tired of feeling sluggish despite all your training, let’s talk. I’ll help you structure your year so you can perform at your best without running yourself into the ground.
Reach out and let’s get to work.