I don't disagree, and that is exactly my point, the difference between a lot of 20min 5km runners and a 15min 5km is not going to be cadence it is going to be stride length. Your speed is simply stride length * cadence. However a lot of athletes still hear the mantra that you have to run at 180spm and to do so they shorten their stride to achieve a cadence of around 180 thereby handicapping themselves. If you are running at your easy pace you should not generally be running at 180 spm, If you are running at 180 strides / min and your pace is say 6 min a km then your sl is going to be 0.92m/stride. Your limiter is not cadence your limiter is stride length. Can we train to improve stride length? Some Factors effecting Stride ( not exhaustive ) leg spring stiffness, ground contact time, range of motion, strength, muscle recruitment, running form, weight. and yes aerobic conditioning. Some of these automatically will improve over time with consistent training but others would benefit from applied specific training.
