Why are rest days part of the plan?

Explainer 2 min read Updated 6 October 2026

Short answer

Because fitness is built while you recover, not while you run. Training is the signal; rest is when your body responds to it. Rest days also lower the risk of the overuse injuries that end many training plans.

Your body adapts to training in the hours and days after it.
Rest days keep hard sessions effective.
A rest day can include walking or gentle stretching.

What rest does

A run puts stress on muscles, tendons and bones. Over the next day or two they repair and come back a little stronger. Without that time, stress keeps piling up, and the result is tiredness, stalled progress and often an injury.

What counts as rest

Full rest is fine. So is an easy walk, a gentle bike ride or some stretching, as long as it leaves you feeling fresher, not more tired.

When to take an extra one

If you feel unusually tired, your easy runs feel hard, or something aches in the same spot two runs in a row, take an extra rest day. It is almost always the right call.

In your plan

Your plan places rest days between harder sessions. Keep them, even in good weeks: they are part of the training, not a gap in it.

When to talk to a professional

Pain that is sharp, gets worse as you run, or is still there the next morning is a reason to stop and get it checked, not to rest a day and carry on.