One of the best changes to come out of the minimalist running movement has been an increase in stride frequency. By increasing frequency, the "over-stride" is prevented as runners have to decrease the stride length as they increase their foot turnover speed. Higher foot turnover can also decrease impact forces on the leg compared with a higher stride frequency (longer stride length) at any given speed.
The study found that increasing stride frequency by 17-18% decreased impact. For example if your foot cadence is 160 strides/minute, increasing by 18% (160 x 1.18 = 188) would yield a stride frequency of 188 strides/minute.
In this study, a metronome was used to help the subjects keep in step with their selected foot cadence.
To count your foot cadence, keep track of the number of times your foot hits the ground in 1 minute. Multiply by 1.18 to find your ideal cadence for decreasing impact forces.
Not everyone needs to decrease impact forces, however. Most running injuries are not directly impact related, but rather, are related to how well we deal with impact.