The stroke-count height index, otherwise known as the Green Zone for your SPL, has been created from observation of thousands of accomplished swimmers and statistical analysis. It is only an estimate of where you may expect to find your optimal SPL range.
Even once a swimmer develops his stroke control enough to move into his Green Zone, he still has to do some experimentation to find out precisely where inside the zone he should train (a smaller ‘sweet spot’ within that larger range).
But there are definitely exceptions to following these estimated Green Zone charts. We cannot say for you which factors apply, but here is a list of the common things that might urge you to consider aiming for a slightly shorter stroke length (slightly higher SPL range):
- You are a female.
- You are older than 50.
- You do not have a competitive swimming background.
- You have a history of shoulder problems, or injury.
- You are swimming in cold water and need to generate more heat (below 60 F, 15 C).
- You are training solely for extremely short sprint racing events (like 100 or 50m).
- You have smaller hands and feet.
- You do not have much swim-specific muscle strength and conditioning yet (training seriously for less than a year)
- You have mobility limitations in your spine, shoulders or hips.
Note a couple things:
- It is often a combination of some of these that may urge a shorter stroke, not just a single one.
- Some of these are improvable or correctable situations.
These factors are listed to help you be realistic about your expectations, but they are not intended to be used as excuses for not improving your stroke length.
If you think any of these factors (or others not listed) are affecting your stroke length, it may be helpful to discuss your specific situation with your coach to think about how these could be tested and your actual potential more accurately estimated.