Why Are My First Lengths Faster?
If you’ve ever noticed that your first length in your intervals is faster than your other lengths, you’re not imagining it. There are two key reasons behind this, and both result from swim behaviour and how lengths are measured.
1. Fresh Starts Are Faster
Our research and data analysis show that swimmers actually do swim their first length faster, on average, by about 2.7 seconds compared to subsequent lengths. That’s roughly a 5–10% difference in speed. But why?
You’re fresher and more powerful at the start of an interval, and many swimmers (especially those who are newer to swimming) naturally push off the wall too hard and go out too fast. Think of it as a burst of energy that is not then able to be sustained through the rest of the set.
2. How Our Turn Times Are Counted
FORM Smart Swim Goggles calculate your speed with precision, but the type of turn you do changes how your lengths are timed:
Touch turns: Your full turn (from the moment your hand first touches the pool wall until your feet leave at push off) gets added to the subsequent length. That means the very first length doesn’t include any turn time, making it look faster.
Flip turns: Turn time is split between the previous and next length. As a result, both your first and last lengths can appear slightly quicker since each only carries half a turn.
What About Smartwatches?
Smartwatches often struggle to detect turns accurately, especially if you switch which hand touches the wall. Many watches simply lump turn time into the previous length, which can make pacing data less reliable. FORM’s approach, by contrast, is scientifically proven, built on extensive video validation to ensure turns and lengths are measured consistently and precisely.
The Takeaway
Rest assured, that “speed boost” at the beginning of your interval isn’t a bug. It’s due to freshness and recovery - a totally normal and naturally occurring swim phenomenon - combined with how your turn times are distributed. With FORM goggles, you’re getting the clearest, most accurate picture of your pace in the water, and that fast first length you’ve questioned is definitely earned, not an anomaly.
