Are You Running Too Much? The Science of Rest Days That Build Endurance

You know that itch you get on a rest day—the twitch in your legs, the internal argument about whether a walk still “counts,” the slight guilt that you're not out doing more? If that sounds familiar, you're in good company. Runners are notoriously bad at resting.

But the truth is: training doesn’t make you fitter. Recovering from training does.

What Actually Happens When You Rest?

Every time you train—whether it’s a long day in the hills, hard intervals, strength training or even strides—you’re applying stress to your system. Micro-tears form in muscle fibres, hormonal shifts take place, and your nervous system takes a hit. It’s not just a workout—it’s a stimulus your body now has to respond to.

That response doesn’t happen while you’re moving. It happens in recovery. That’s when your body gets to work—repairing tissue, replenishing glycogen, recalibrating hormones, and reinforcing neuromuscular patterns. The real fitness gains happen when you stop.

And it’s not just your muscles that need the break. Your central nervous system (CNS) plays a big role in coordination, balance, proprioception, and emotional regulation—especially when training gets mentally demanding. Back-to-back runs, technical descents, poor sleep, stress at work... it all loads the system.

Without time to reset, CNS fatigue builds quietly. That’s when your form starts to fall apart. You clip a rock, zone out on fuelling, or just can’t seem to switch on. No amount of caffeine or willpower fixes that kind of tired—it needs rest.

What Counts as a Rest Day?

Here’s where many runners (especially ultrarunners) go wrong: assuming “rest” just means “not running.”

If your idea of a rest day is bagging a Corbett, doing a 3-hour “recovery hike,” or chasing your 15K steps, you’re not actually resting—you’re just replacing one type of load with another.

A true rest day should feel like a noticeable drop in physical, mental, and emotional stress. For some people, that might look like:

• Doing as little as possible

• Walking the dog gently, not climbing a hill

• Pottering, napping, stretching

• Reading, journaling, getting a massage

• Low-effort movement only if it feels restorative (and not because your watch told you to)

If you finish the day feeling like you could definitely train tomorrow, you probably did it right.

What About Deload Weeks?

Just like rest days, deload weeks are where long-term training clicks into place. They’re planned periods (usually every 3–6 weeks) where overall volume and/or intensity drops to allow full recovery from accumulated fatigue.

These weeks might feel counterintuitive at first—you’re capable of doing more, so why pull back? Because adaptation takes time, and the body responds better to strategic undulations than constant pressure.

A good deload might include:

• Fewer runs or reduced mileage

• Swapping hard sessions for easy aerobic ones

• Lower volume strength work or skipping the gym altogether

• More sleep and low-stress routines

There’s No One-Size-Fits-All Rest Rhythm

Some runners need a full rest day every week. Others thrive with one every 10–14 days. Some need regular deloads; others can go longer before they start to fade.

What matters isn’t what your running friend is doing, or what an online plan says—it’s what you respond to. That’s why working with a coach helps: they can spot subtle signs of fatigue before they derail you and adjust the load accordingly. They’ll look at your life outside of running too—stress, sleep, energy, motivation—not just what your legs are doing.

Rest is individual. The sweet spot isn’t fixed, it’s dynamic. Learning where yours is—and listening when it shifts—is where sustainable progress lives.

If You’re Still Not Convinced...

If your training has stalled...If every run feels a bit harder than it should...If niggles are creeping in...If motivation has dipped for no clear reason...

It might not be your fitness. It might be your recovery.

Final Thought: Real Progress Isn’t Just About What You Do—It’s About What You Don’t

There’s a quiet discipline to rest. To stopping when you could keep going. To zooming out and seeing the full training picture—load, yes, but also pause.

Adaptation isn’t linear. Progress needs space to settle.

So next time you’re tempted to sneak in “just a wee run” on your rest day, ask yourself: what am I really training here—fitness, or fear?

Interested in getting a run coach?

If you’re tired of second-guessing whether you’re doing too much or not enough, working with a coach can take the guesswork out of your recovery—and help you find that sweet spot where progress actually sticks. Whether you’re training for your first ultra or chasing a breakthrough, I’ll help you balance the big days with the right kind of rest, so you’re not just running more, but running better.

Let’s chat about what that could look like for you.

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