According to Grant Robison, 2004 Olympic 1500m runner, three-time NCAA champion, 10-time All-American at Stanford University and co-developer of Good Form Running, cadence, the rate at which your feet move while running, is arguably the most effective tool for maximizing the efficiency of your stride.
"The goal of cadence," Robison says, "is simply to eliminate overstriding [when your feet reach out too far in front of your body, causing you to land on your heels], so every ounce of energy put into your stride moves you forward efficiently. Cadence is effective in achieving this by providing a simple, measurable tool to focus on. Overstriding creates braking and rotational forces that make you both inefficient and more susceptible to injury."
To begin refining your cadence, go for a run. A few minutes into it, count how many times your left foot touches the ground in 20 seconds. Multiply this number by three to determine your "strides per minute." For improved cadence, try to get a few more touches into those 20 seconds without speeding up your pace. "Again, cadence is about making your stride extra efficient, not just running harder," Robison says.
Many running experts, including the legendary Jack Daniels, argue for a prime cadence of 180. To achieve this, get your strides per minute up to 85-90 left foot touches (170-180 steps per minute).
According to Robison, leg length does not play a large role in striding. "Pace is more controlled by length of stride as [your legs] pull through and out behind your body," he says. "During sprinting, longer legs may equate to having a potentially higher top-end speed, like Usain Bolt, but it certainly doesn’t guarantee it. During aerobic activity, cadence works regardless of body makeup."
If your cadence needs improving, focus on tweaking it during your easy runs, and build that muscle memory, so at race time your body will recognize the difference a quicker stride makes. If you’ve already achieved successful cadence, focus on keeping your head level when you run.