Common Marathon Training Mistakes I See New Runners Make (and what to do instead)

Most marathon training problems don’t come from effort. They come from doing the right things in the wrong order.
Every training cycle, I see the same patterns show up—early fatigue, long runs falling apart, and race day feeling harder than expected.
Here are the most common mistakes behind it, and what to do instead.

Mistake #1: Doing too much, too soon

You feel good early in the plan. Mileage climbs quickly. Long runs stretch earlier than scheduled. Recovery weeks get skipped because nothing hurts yet.

At first, it feels productive.

Then easy runs stop feeling easy. Small aches linger longer than they should. Fatigue sticks around even after rest days.

This is where training starts to unravel.

Your aerobic system adapts gradually. Tendons, bones, and connective tissue adapt even more slowly. When training load jumps too fast, fitness can’t keep up with fatigue.

That doesn’t build durability. It just makes every week harder than it needs to be.

The fix isn’t backing off completely. It’s building progressively enough for adaptations to stack.

That might look like:

• Weekly mileage increasing in small, planned steps.
• Long runs grow only after shorter runs feel stable
• Scheduled lighter weeks instead of pushing straight through

Mistake #2: All Your Runs Look the Same

This one is harder to notice.

You’re running most days. You’re not racing workouts. Nothing feels extreme. Every run ends up at the same pace.

That’s the issue.

When all your runs feel the same, none of them do their job particularly well.

Easy runs aren’t easy enough to support recovery. Hard sessions aren’t hard enough to create a meaningful training signal. You accumulate fatigue without clear adaptation.

Easy days create space to absorb training. Hard days give your body a reason to change. When those lines blur, progress slows.

The solution isn’t more intensity. It’s a clearer separation.

That might look like:

• Easy runs that truly feel relaxed
• Hard sessions with a specific purpose
• Fewer “in-between” efforts that just add fatigue

Mistake #3: Never Practicing Marathon Pace

Marathon pace is one of the most misunderstood parts of training.

Some runners avoid it entirely. Others force it too early and too often.

Both approaches miss the point.

Marathon pace isn’t just a speed. It’s a specific metabolic and muscular demand that your body has to learn how to sustain.

If you never practice it, race day becomes a guessing game. If you overuse it, fatigue accumulates before your body is ready.

Timing matters.

As race day approaches, training should become more specific. That’s when marathon pace work earns its place.

Not all season. Not every week.

Controlled exposures teach your body what “sustainable” actually feels like without overwhelming the system.

That might look like:

• Marathon pace blocks inside runs
• Controlled marathon pace segments rather than workouts built entirely around it
• Gradually increasing duration as fitness stabilises

The goal isn’t to prove fitness. It’s to prepare your body for the demands you’ll face late in the race.

Mistake #4: Underfueling Long Runs (and Never Practicing Race Fueling)

This mistake usually shows up later in the build.

Long runs start well. Then energy drops sharply after 90 minutes. Pace fades. Form slips. The run turns into survival mode.

Most runners assume this means they’re not fit enough.

But it can also be a fueling issue.

Once runs extend beyond 90–120 minutes, carbohydrate availability can become a limiting factor for many new marathoners. Without fuel coming in, training quality drops, and fatigue rises.

Just as important, race day fueling isn’t something you want to experiment with for the first time on race morning.

Fueling is part of training.

Practising carbohydrate intake during long runs supports the session itself and helps your gut adapt over time. That reduces the risk of GI issues when it matters most.

This is where familiar options runners already use can help—higher-carb gels for longer efforts, or smaller, more frequent doses while tolerance builds.

That might look like:

• Taking in carbs during long runs, not just races
• Practising timing and formats well before race day
• Treating fueling as a skill you train, not a last-minute detail

If you’re wondering what this looks like in practice, many runners use lower-dose options like GO Isotonic Energy Gels earlier in the build, then transition to higher-carb options like BETA Fuel as long runs get longer.

The product matters less than practising timing, tolerance, and consistency well before race day.

If long runs consistently fall apart late, fitness isn’t always the missing piece.

A simple checklist to keep training on track

If you want to avoid most marathon training mistakes, focus here:

• Build gradually, even when motivation is high
• Separate easy and hard days so each can do its job
• Earn marathon pace work as race day approaches
• Fuel long runs like race rehearsals, not tests of willpower

Marathon training doesn’t need to be complicated.

Most problems come from stacking too much stress, too quickly, without enough structure or preparation.

Get the order right, and training gets simpler. Ignore it, and even a good effort starts working against you.