Question:
I was listening to a podcast today and they had some interesting thoughts about stride length/cadence, with the end result being that stride length is at least as important as cadence in marathon runners.

Matt has mentioned, though, that cadence is the strongest predictor of run performance in an IRONMAN. Could the reason for that be athletes are just not strong enough at the end of the race to take bigger steps with good form? Could it be a case of correlation and not a cause? Both are important, obviously (at least from a physics standpoint), but is there any type of athlete who should not shorten their stride length just to get the cadence up?

Answer: 

Speed is a combination of stride length (propulsive phase) and steps per minute (stride rate if you like?).

The same applies to swimming:

Stroke rate and length of stroke.

There is little value on increasing stride length to bounding-like leaps if your number of steps per minute radically reduces.  This also applies to swimming, although a common myth amplified by many poor coaches is that success comes from just that -- aiming to take fewer strokes each lap.  That’s like running around a track with your only barometer of success being reducing the number of steps. It would soon resemble the Ministry of Silly Walks (https://www.dailymotion.com/video/x2hwqki).

So, yes, we want a balance in the relationship between stroke rate/steps per minute and the length of stride/stroke.  The difference between swimming and running is that swimming is a pulling sport, while running is (or should be!) a pushing sport.  This has massive ramifications on your question.

Here is a simple way to think about things. 

• A long stride length is optimal, as long as the foot is at the hip line of the back (behind you).
• We want to minimize or eliminate any time that the foot is on the ground in front of the knee or hip line.
• The faster we can get through each running cycle and sustain, the better it is.

We should never shorten the stride length by picking up the foot early behind us. You will see many athletes flicking the foot up and not pushing through their big toe, almost like they are running while performing butt kicks.  This is less preferred.

The route to get to optimal stride length and foot speed is:

1. Great posture (stand tall with a strong and stable trunk)
2. Slight lean (from the ankles) to get the center of balance forward
3. Arms driving behind us and shoulders supple.

With these three elements, you can then pick up foot speed as much as possible while keeping it sustainable.   So lean into the very basic elements of good form instead of actively trying to ‘shorten the stride’ or even ‘lengthening the stride’. 

I should add that, with good basic form elements in place, the natural promoter of all of this is hill-based intervals.  Hill running and hill intervals are a wonderful opportunity to, well, improve!  They will make you better -- but -- only if you approach with vigor and intent.