A planned walk break changes how you cover a marathon. You decide where walking fits before the start, alongside your running pace, rather than leaving it as a decision for the final miles.
Run-walk pacing alternates the two movements throughout the session. Walking makes that section slower, but your finish time also depends on the pace of the running sections and how that pace changes over the distance. The complete pattern is what you need to assess.
In a small randomised trial published in 2016, 42 recreational runners completed a marathon using either a run-walk strategy or continuous running.
The run-walk group averaged 4:14:25; the continuous runners averaged 4:07:40. The difference was not statistically significant. That does not prove the strategies are equally fast: a small study can miss a meaningful difference. It also cannot predict your own finish time.
The run-walk group reported less muscle pain and fatigue immediately afterwards. The study did not demonstrate lower cardiovascular stress, however. Its comfort finding should not become a claim that walk breaks protect the heart or prevent injury.
Finish time and the experience of covering the distance are separate outcomes. For a recreational marathoner, both can be worth considering when choosing a pacing approach.
The arithmetic needs to include the walking. Nine minutes running and one minute walking form a ten-minute block; its average pace includes both parts. That is an illustration, not a recommended ratio. Looking only at running pace leaves part of the race out of the calculation.
Rehearsing the approach during familiar training gives you something more useful than a theoretical target. Keep the session within your existing programme and agree any changes with your coach if you have one. Notice whether restarting feels smooth and how the later running sections feel. Avoid speeding up automatically after every walk to chase the display on your watch.
Planned walking is a pacing choice to evaluate across the whole distance. Give it a fair rehearsal, count every minute and judge the result against the finish you want.