I swam virtually the same practice, five days apart, Wed Apr 28 and Mon  May 3. (In between I swam 5 miles in the Hudson River on Sat May 1.)

Why do the same practice twice? To learn the effect of a small, but perhaps meaningful change.  Coaches commonly aim for variety in training, but in many instances it’s hard to see that the variety has a purpose other than to relieve tedium. I never experience tedium in my training because every practice and set has a clear purpose. The variation I included to distinguish these two sets was subtle, but I wanted to learn whether a slight change in rest interval could produce a meaningful change in how I swam.

Here’s the basic practice:

3 rounds of 10 x 100 Free (scy).

And here’s the variation. On Apr 28, I swam the three rounds on intervals of 1:30, 1:35 and 1:40. On May 3, I swam identical sets on intervals of 1:35, 1:40, 1:45.

The question: Would an increase in rest of just 5 seconds per 100 lead to a measurable improvement in my swimming?

Here’s how I swam each practice:

1^st round: Hold all 100s  at average of 14 SPL, aim for best average pace.

2^nd round: Increase rest interval 5 seconds. Hold same SPL but gradually improve pace on 1-5 and 6-10. I increased pace on each set (of 5×100)  by adding power to my stroke, while aiming to keep same Stroke Length or SPL

• 1^st & 6^th 100.  Easy and light.
• 2^nd & 7^th 100. Add power last 25.
• 3^rd & 8^th 100: Add power last 50.
• 4^th & 9^th 100: Add power last 75.
• 5^th & 10^th 100: Add power full 100.
• I added power by increasing pressure on hand and forearm and adding snap to each “toe-flick” on 2BK.

3^rd round: Increase rest interval by additional 5 seconds.  Aim to swim as well or better as in 1st round, but with slightly greater ease.

(On May3, having more time, I swam a 600-yard tuneup before the 1^st round [4 x 25 + 4 x 50 + 4 x 75, @ 13-14SPL, aiming to hold same average pace as distance increased]. Then I finished the practice with 12 x 25 on :30, holding 13 SPL and aiming to swim as fast as possible. I swam those 25s mostly in 17 seconds, with 2 or 3 at 18 seconds.)

How did an additional 5 seconds rest change my swimming? I found it noticeably easier to hold my intended Stroke Length.

On Apr 30 I swam the 1^st round in 1:22 to 1:21, but it was a strain to hold 14SPL after the 3^{rd or 4th} 100. On May 3, I swam the same paces but was far more consistent at 14SPL.

On Apr 30, I descended the 2^nd round from 1:22 to 1:17 on 1-5 and 6-10, but my SPL frequently went to 15. On May 3, I descended from 1:22 to 1:17 on 1-5 and 6-10 again, but held 14 SPL consistently, adding a stroke on only one or two lengths.

On April 30, on the 3^rd round, I held 14 SPL throughout and swam with slightly greater ease, but my pace slowed from the 1^st round to 1:23-1:24. On May 3, I held 14 SPL and swam with increased ease, but my pace equaled the 1^st round, improving gradually from 1:22 to 1:21.

What did I learn? That even a modest increase in rest interval can measurably improve ease and efficiency. And that this can translate into an improved pace near the end of  an extended (3000 yard) set.

I plan to swim a virtually similar set at least one more time in the next several days.  Next time I’ll convert the 100s into 200s (i.e. 5 x 200 in each round, rather than 10 x 100). I’ll keep the rest interval  similar. What I hope to learn is how closely I can match my 100 pace and SPL when my repeat distance doubles.  I’ll let you know how that goes.