Most runners strive to run faster. At least ones who find themselves huddled around results page after the race, trying to figure out their finishing time and comparing it to the last race. In order to increase the running speed, we first need to understand the components of running speed.
Running Speed (RS) is a simple function of Stride Frequency (SF) and Stride Length (SL). The simple equation looks like this :
Running Speed (RS) = Stride Frequency (SF) X Stride Length (SL)
SF represents the leg turnover or the number of strides you make over a period of time (usually measured in strides (steps) per minute). You may have read and/or heard that 180 steps/min is the magic number when it comes to SF, but there is no exact science to it. Most elite runners average around that number with some of them capable of a much higher turnover at the end of the race. Average (age group) runners typically range 150-170 steps per minute. The simple way to measure your SF is to count the number of times your right foot hits the ground in one minute and multiply it by 2.
SL represents the distance you cover (in feet, inches or meters) with each stride. SL depends on your biomechanics, your fitness level, muscle strength (particularly your glutes), hip mobility and flexibility of the muscles in your lower body. The simple way to measure your SL is to measure off 50 meters, run for 5 minutes at your easy pace then run the area and count the number of steps required to cover that 50 meter distance. Divide the distance by the number of steps and there you have it (SL = 50m / #of steps). You may want to do it at differents speeds and compare the results.
Lets look at these 2 examples.
If we compare runner A, who has a SF of 150 steps/min and covers 1.8 meters of space with each stride, to runner B, who has a SF of 150 steps/min (same SF as runner A) and covers 1.6 meters of space with each stride, runner A will run a 5K in just over 18 minutes, whereas runner B will require close to 21 min to do the same thing.
If we compare runner A, who has SF of 160 steps/min and covers 1.8 meters of space with each stride, to runner B who has a SF of 150 steps/min and covers 1.8 meters of space (same SL as runner A) with each stride, runner A will run the 5K in just over 17 min, where as runner B will require over 18 minutes to do the same thing.
Looking back at our equation from earlier (RS=SF X SL) and our two examples, we can conclude that in order to increase running speed we can either increase one of the two or both, SF and/or SL. Which way you go about it is really a matter of choice and the method of training you choose. I do not recommend you become biased towards any of these particular methods, because all three can work. One may work better for you, but it does not mean it works best for everyone. Try (I recommend) all of them and decide (conclude) which worked the best for you.