Some beginners start out using a run/walk technique because they don't have the endurance or fitness to run for extended periods of time. Here’s what you should do for your walk intervals.
Don't wait too long to start your walk interval.
You should start your walk portion before your running muscles get too tired. This will allow your muscles to recover instantly, which extends the time and distance that you can cover. If you wait until you're very fatigued, you'll end up walking slowly and it will be difficult to start running again.
Maintain good form.
When walking, don't lose your good running form. Make sure you keep your arms at a 90 degree angle – don't drop them to your side and walk casually. Keep your stride short, so you're not putting stress on your hamstrings and your shin muscles.
Don't be tempted to take it easy and slow down too much during your walk breaks. You want to keep your heart rate elevated so it's easy to transition back to running.
Adjust your walk schedule, as necessary.You may need to alter your walk break frequency to adjust for breaks in your training, course conditions, and weather conditions. Don't stick to a rigid walk break schedule – take more frequent walk breaks if you need them.
Also see: Beginners' Guide to Run/Walk
Am I Allowed to Walk During a Race?