PUBLISHED 03/03/2005
You've seen them before: runners bending over after hard speed intervals, gasping for air. You've probably done it yourself. That's because your body knows that the heart has to pump harder when you're standing at full height. Putting your head at the same height or lower than your heart gets blood to your brain faster--and makes those blasted spots go away.
But your body doesn't know everything. It doesn't know that lying on the track's infield between quarter-mile repeats will actually make things tougher for your heart. Your tired legs act as a passive pump when you run, helping to move the blood toward the heart. So, when you suddenly stop moving your legs, the heart loses a powerful pumping ally.
In fact, the best way to help your body recover between hard intervals is to keep moving--something exercise physiologists call "active recovery." And a recent study has confirmed that incorporating active recovery segments into your speed sessions will also help you get a better workout.
Spanish researchers had 10 healthy students perform four intervals of cycling at 120 percent of their VO2 max until they were exhausted. Between the work intervals, the subjects either pedaled lightly at 20 percent of their VO2 max, stretched lightly, or lay down, all for five minutes. Active recovery won the gold medal, with stretching and lying down taking a distant silver and bronze.
When the students pedaled easily between work intervals, they performed 13 percent more work in subsequent intervals than when they lay down, and nine percent more work than when they stretched between segments. Active recovery also enhanced "peak and mean VO2." In English that means the subjects were able to use more oxygen after active recovery, allowing them to reach higher levels of aerobic intensity and get a better workout.
To replicate the active recovery used in this study, simply jog slowly but steadily between work intervals. However, more is not necessarily better: If your heart rate fails to drop below 60 to 65 percent of your maximum heart rate, your active recovery pace is too fast or you need more time between work intervals.
