If you want help building your basic speed, why not enlist gravity? Doing striders on a slight downhill can enhance all the benefits of doing them on flat ground, especially your ability to maintain a relaxed, quick cadence at high speed.
The key is to do downhill striders on a relatively gentle descending grade. If it’s too steep, your form will be too different from how you run on flat or slightly uphill stretches. A 1 percent or 2 percent grade is good.
As on regular striders, focus on running fast but relaxed. Hold back a bit on the first couple to make sure you’re adequately warmed up, and then let ’er rip—on the last several of a set of 10 striders, see how fast of a turnover you can maintain without your form deteriorating. Walk or jog gently up the hill in between. After a month of weekly downhill striders, you should notice improvements in your form on your hard workouts and in your speed at the end of races.