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Marathon Base Building FAQs: What’s Normal vs. A Red Flag

You’re building mileage.

You’re doing the work.

You expected to feel fitter by now…


…but instead your legs feel heavy. Flat. And Kind of dead.

Let me answer your most commonly asked questions of "why do my legs feel like..." as you stack highly weekly miles.


Because there's a fine line (and a lot of googling done) between "I'm working hard and this is fatigue" and "is this turning into a injury and can I stop it?"


So let your friendly neighborhood physical therapist give you real life, practical, and immediately applicable, actionable answers to the running questions rolling around in your head.



“I’m increasing mileage, but my legs feel worse. Why isn’t this getting easier yet?”

First: this is normal to a point.


High mileage builds do come with fatigue. Your body is adapting to more volume, more impact, more time on feet.

However there’s a difference between “tired” legs which is expected and “toasted, lead, dead” legs which can be a lingering red flag

Before you spiral, make sure you're meeting your basics (yes, I’m making you do this):

  • Are you eating enough?

  • Sleeping 7–8+ hours?

  • Actually running your easy runs easy?


If those boxes are checked, here’s the big one most runners skip:

Your legs might not be strong enough for the mileage yet


If you’re not strength training 2–3x/week (and no, not booty banded circuits and quick 12 core workouts)...


Your muscles don’t have the capacity to handle what you’re asking them to do.


So what happens?

You don’t feel “fit" at all. You feel beat up.


What to do about it? Lift heavy 2–3x/week, prioritizing single-leg work (split squats, single squats, calf raise varations). I have a lot of exercise circuit options in my other blog posts.


But realize, mileage builds have a humbling way of exposing strength gaps, not necessarily creating them. So get to work ;)

“Are my legs just tired…or am I getting injured?”


Here's the exact checklist I take my runners through either in the clinic or strength or rehab coaching. Because when we have a plan, we work the plan, not the panic.


Step 1: Run & Rest

  • Cut mileage by 30–40% for one week

  • Take 1–2 extra unplanned rest days


Step 2: Wait & Watch

  • If things calm down and you start to feel stronger again, we can chalk things up to fatigue

  • If things only minimal improve and symptoms linger, we can say a potential injury may be brewing


Step 3: Reality Check

  • We ask the hard questions: have you been lifting consistently?

  • Or just kind of "spot treating" with random circuits when you have the time?


Step 4: Strength Targeting

  • This is obviously dependent on the niggle or brewing-running injury you're experiencing, but I pull out targeted, running specific strength to give to my runners.

  • Example: knee niggle. Focus on single-leg squats, especially the eccentric portion of the rep and bulgarian split squats (yes, they’re awful, but do them anyway)


"If I pulled my calf muscle, do I need to stop running or can I train through this? Can I still strengthen this muscle if it’s in recovery mode?”


Short answer: yes to running, yes to strengthening!

Long answer: be smart and pay attention to how it behaves.


If:

  • You’re not limping

  • Pain stays low (think mild tightness)

  • Easy runs feel okay

  • But speed work feels questionable (this is normal)


...Then yes, you can usually keep running. (obviously don't be trying to grit your teeth through speed sessions right now. It's NOT going to end well).


But pay attention to this next part:

“Training through it” does NOT mean ignoring it


We’re not comitting to a grind-it-out, suffer-through-everything mindset.


Your course of action is:

  • Keep mileage easy

  • Drop intensity (no chasing pace, no hero workouts)

  • Prioritize recovery


And most importantly: You still need to strength train

Because healing happens when overload is applied correctly

We don't rest forever or stretching endlessly.


Tissues only adapt, heal, and get stronger to run another day with consistent, progressive load.


And if you're looking for exactly HOW to do that and save your tight, unstretchable, and maybe achey Achilles, check out my 100% FREE Calf and Achilles Cure Toolkit:



“Is running on a 3/10 hamstring pain ok or too risky?”

Here’s your quick filter.


You’re generally okay to run if:

  • It shows up at the start of the run

  • It improves as you warm up

  • It stays at or below 3/10

  • It becomes just an occasional twinge, not constant pain


If that’s your situation, it's ok to keep running, but stay smart.

If it’s getting worse, sharper, or lingering after runs, that's a different story and your body is telling you it's rehab time.


“I know I'm adding more miles each week, but why are my calves so tight lately? Am I doing too much or am I not fit enough?”


Overuse: always a possibility

But more likely? Your calves just aren’t quite strong enough yet


Here’s the test I give my runners:

Can you do 35 single-leg calf raises?


Not kinda. Not sloppy. Full range.

If not, there’s your answer.

Often, tight calves are just underpreppared calves.


But why 35?

Because running is thousands of single-leg calf raises in disguise.

The old PT standard was ~25 reps.

But for runners, the bar is higher.


I've found that once runners hit that 30–35 range consistently, something clicks:

  • Less tightness

  • Better push-off

  • More endurance and less tightness at higher mileage


So what to do?

Make it easy and train calf raises 2x week with my Calf and Achilles Tookit. I've put all my best running-specific exercises inside of it. So you don't even have to decide which exercses you need to do. Just show up and get the work done.



WRAPPING UP

It's sanity-confirming to know that most of what you’re feeling right now isn’t random.


It’s just your body checking in and telling you one of three things. You need:

  1. more recovery

  2. more strength

  3. or better load management


My goal for you isn’t to have you stop running every time something feels off.

It's to understand what your body is telling you and adjust without losing momentum.


Because you don’t need perfect training.

You just need smart training that keeps you running.


Until next time running fit fam.


Dare to Train Differently,

Marie Whitt, PT, DPT // @dr.whitt.fit

 
 
 

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