Your body needs rest to recover and get stronger from hard workouts. Rest and active recovery (including gentle cross-training) are both tools we can use to achieve our fitness goals.
A rest day doesn’t involve exercise at all. Think of these days like a good night of sleep. Plan to completely relax: sleep in, enjoy family time, or do light errands or housework. Avoid strenuous tasks like raking the yard, painting the house or helping a friend move.
An active recovery day, on the other hand, is more like a short nap. You’re including activity — running or cross-training — at an easy to moderate intensity to get blood flowing to your muscles to help them recover. Do low- or no-impact activities like cycling, swimming, yoga or strength training to complement the demands of your high-impact running workouts. Runners who run more than three days per week can use easy runs as active recovery, too.
Optimal recovery includes both complete rest and active recovery. Cross-training (that is, performing any exercise that isn’t running) can be part of that, but it doesn’t have to be, and more strenuous cross-training is too taxing to count as active recovery.
If you’re building up your training to reach a goal (a first-time finish at a new distance or a PR) or just getting back into running, you should only cross-train at easy to moderate effort levels to balance the demands of your running workouts. If you’re using running as active recovery, keep the duration and intensity easy.
If however, you’re running for fitness, you have more flexibility. For example, if you run three times per week, three to five miles at a time, for the health of it, you could make one run a high intensity interval workout, one a short, easy effort, and one a long, easy effort. Because you’re not building intensity and volume each week to work toward a race, you can fill in the gaps with cross-training at different effort levels. You might do a hill workout on your bike or go to a challenging yoga or strength class. The key is to include two or three harder workouts each week with plenty of easy and moderate activity to balance it out.