Using the Math of Speed to Achieve A ‘Dream Swim’
by Terry Laughlin

Posted on October 12th, 2015

This post provides a ‘real life’ example of how one swimmer can improve her speed–and achieve a dream–by using the TI Principles-based approach I’ve described in several recent posts.

This month I’ll spend a ‘fortnight’ in the UK leading workshops and training coaches. While there I’ll also spend a couple of hours with Helen Webster, editor of 220, the UK triathlon magazine, introducing her to the TI Method in TI Coach Tracey Baumann’s Endless Pool.

A happy Helen après swim

A happy Helen après swim

I queried Helen on her swimming history and perceived needs or priorities to ensure we would focus on her priorities. Here are her responses:

I hadn’t swum before coming to work at 220 magazine two years ago, so I’m a complete newbie! I’ve had a few lessons so I can swim front crawl now and have completed around 10 triathlons, swimming up to 1500m in open water. I’m keen to get all the advice and help I can. I may be slow, but I’ve really fallen in love with swimming and have lots of enthusiasm!

 My endurance is pretty good, but I’ve hit a plateau. I swim 2k in about 55mins, but can’t seem to get faster. I swim 4x a week for an hour but don’t have a structured plan and thus I mainly just do lengths.

 I’ve gotten feedback from coaches of areas I need to focus on, but I struggle to prioritise them. Besides swimming faster, being able to complete a 5km swim in the Lake District next summer, in a reasonable time, is the dream!

Helen also included a link to a video shot by Gabriel Lombriser at a training camp several days earlier.

I replied

I’m delighted that you’ve fallen in love with swimming. I’ll do my best to deepen those feelings. Your video provided invaluable information and insight—both on your form, and on the ‘math’ of the speed at which you’ve plateaued. By ‘math” I mean that your pace is the exact product of how far you travel on each stroke (Stroke Length) and how frequently you take them (Stroke Rate).

Though the video didn’t show complete lengths, I estimate you took about 36 strokes per 25 meters. I timed 10 strokes at two points to learn your Stroke Rate, which was .83 sec/stroke both times. [For sake of comparison, my tempo while racing 1500 meters in open water is about 10 percent slower–between .95 and 1.0 sec/stroke–but I’ve worked many years to acquire the skill to keep my stroke efficient at that rate.]

I see you use a kind of ‘windmill’ action. Look for this in the video: Your arm is at full extension when it first appears beneath the surface and immediately begins pushing back. There is no lengthening component in your stroke. This is highly typical of new swimmers.

How long should your stroke be? Our Green Zone chart gives a height-indexed range of efficient counts for 25 meters.

In TI technique, your arm’s most important role is to lengthen your bodyline . . . and to ‘separate’ the molecules in front of you–the function performed by the sharply tapered nose of an F-15 fighter jet, bullet train or barracuda. Both help in significantly reducing drag.

Like all human swimmers, your upside on reducing drag is almost limitless, while that on increasing propulsion is quite finite.

Thus we’ll focus on significantly increasing your stroke efficiency by adding a lengthening-and-separating phase. We’ll start with Balance, the ‘non-negotiable’ pre-requisite to a long—and far more relaxed–stroke.

Helen replied

I counted strokes this morning in a 25m pool and you’re right; I range from 33 to 36 SPL. According to your Green Zone chart, at my height of 67 inches, I should be taking 17 to 21 strokes. Quite a difference!

 I’ve heard before that I swim with a ‘windmill’ stroke but haven’t had a clue about how to fix this. Even when I understand I’m doing something wrong, trying to make my arms do something different often seems pretty near impossible!

I wrote back

I’m glad this makes sense. Here’s how an increase in stroke efficiency will enable you to improve speed almost effortlessly. We’ll apply the Math of Speed formula (Velocity = Stroke Length x Stroke Rate or V = SL x SR) to what the video reveals about your swimming.

Allowing 3 to 4 seconds for the pushoff, your pace at 33 strokes and .83 tempo should be about 31 seconds. (.83 seconds/stroke x 33 strokes/length = 27.4 seconds per length [swimming] + 3.5 seconds [pushoff] per length = 31 total seconds per length.)

If you continued beyond 25m, within a length or two–feeling fatigued from your high stroke rate—you probably slow your stroke a bit, but your SPL has increased to 36. This mathematically produces a pace of 37 to 38 sec per 25—or approximately 2:30 per 100m. Is this reasonably close to your actual training paces? [After receiving this message, Helen timed herself for 100m repeats and found she does indeed start at 2:30, then slows to about 2:38 per 100.]

If you bring your stroke count into your Green Zone by improving the TI ‘foundation’ skills of Balance, Core Stability and Streamline, here’s how the math changes. Suppose our initial goal is for you to be able to swim a pace of 2:00/100m (30 sec/25m) with such ease that you can maintain it indefinitely.

Calculating as above tells us that at 21 SPL—the highest count in your Green Zone–you need only stroke at a tempo of 1.24 sec/stroke. At this strikingly more relaxed tempo, you’re likely to feel far more ease . . . and consequently, maintain that pace almost indefinitely without fatigue. Improving by 25 seconds per 100m would project to an improvement of about 8:00 in your current 2K time—from 55 to 47 minutes. And with further practice I would expect two changes in your swimming.

  1. You should lower your average SPL at a 1.24 tempo. A 1-stroke improvement (to 20 SPL) would carve an additional 4 seconds/100 or 1 minute 20 seconds for 2K from your pace.
  2. OR being able to hold 21 SPL at, say, 1.14 tempo (a tenth of a second per stroke faster) would result in the same pace improvement. In practice, it will probably be a little of each.

Step One is to develop a strong efficiency foundation that 10 to 20 hours of practice should bring you to comfortably and consistently swimming at 20 to 21 SPL. A few months of ‘encoding’ new skills over the winter should put you in a place to swim sub-50 minutes for 2K . . . and confidently undertake your ‘dream swim’ of 5K in the Lake District.


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