If you run on a treadmill, be sure to add in some elevation and speed changes to avoid overuse injuries.
If you run on an indoor track, go easier on the curves, and faster on the straight-aways to protect knees and ankles.
Remember not to overdo it. Your total mileage this week should not be more than 10% higher than your average over the past 3 weeks. Do not do a significantly longer run than your longest run in the past 3 weeks.
Fartleks (Swedish for “Speed Play”
About 10 minutes into your run, you will do a series of faster paces followed by an equal recovery.
It could be 30 seconds fast/30 seconds slow, or 1 short block fast/1 short block slow. The time does not need to be exact, but try to keep it close.
You should be able to jog your recovery. If you have to walk, slow down your “fast” section.
“Fast” is not an all-out sprint. It should be fast enough that you can’t have a conversation, but you could give 1-2 word answers.
Finish by running at least 10 more minutes at a comfortable pace.