Stride Length & Cadence
The two variables affecting running speed is stride length (SL) & stride rate/cadence (SR). There's been some debate & research over the last ten years and the here are the conclusions I've collated.
It seems athletes favour either longer strides or increased cadence. It maybe due to differences in the nervous system or power generation. Powerful athletes may rely on generating a large amount of force thru' their stride and become stride length dependent. Or runners that rely on the nervous system's ability to rapidly turns the legs over become reliant on stride frequency.
In conclusion SL is related more to increased force production & SF is associated with faster leg turn over and neural activation.
So to enhance performance we can individualise training. Stride length dependent athletes might need to do more turnover workout/neuromuscular work to improve their SR and therefore speed. If we can run sub-maximally with our natural strategy and then be able to switch strategies when fatigued you can change the muscle fibres that are recruited slightly, and thereby changing how they work (powerful as in a long swing stride or rapidly as in a short swing stride).
The 180 steps/minute is just a guideline, even elite runners vary off this number a little. Increasing your cadence if it's a lot less than 180, helps because:
To eliminate over striding.
To give you another weapon in your running arsenal.
For example nearing the end of a race if you change to a faster turnover rate you recruit fresh muscle fibres capable of producing a sprint finish. But this takes practice, adding weekly doses of speed training, teaches the nervous system to fire and apply force in a quicker amount of time. Speed work teaches the body to push off against the ground more powerfully in a short period of time.
If you want to increase your stride length do not reach forward this may lead to over striding and produce a breaking force. Better to lengthen it out the back side. Use your gluteus & hamstrings to create propulsion.
Several ways to do this:
Plyometrics; explosive exercises, jumps produces more force with less ground contact time, for us distance runners this would translate to a more powerful stride.
Bounding; exercises like single leg bounds increase your running economy and teach you to extend your stride out the back.
Avoid Over Striding
Over striding is sometimes seen in runners with low cadence, it not only can slow you down (breaking force) but puts undue stress on your joints increasing risk of injury. If you're prone to this, the easiest and most efficient way to cut down on over-striding is to increase your cadence. Tools to help achieve this:
We ideally hold our arms at 90-degree angle, but if you increase this it creates a smaller arc for the arms to swing thru' forcing the legs to turn over quicker.
Try some barefoot running in grass field for several minutes, then pop on your trainers and mimic these shorter barefoot strides.