Author Archives: Bryan Allott

Using Swimsense™ to Understand Workout Details On the Fly

You’ve been using the Swimsense for a couple of weeks now and getting used to analysing the data. You’re comfortable wearing the watch while you swim and you are happy with the recording capabilities and feedback available. The Swimsense dashboard is a great tool in this regard and if you spend some time reflecting on specific sessions, you start getting used to your numbers. For example, I know without thinking too hard that my average stroke count is 9 cycles per 25m, I have an average distance per cycle of 2.5m; my training pace is around 1min 20sec per 100m; my stroke rate is 0.90. These numbers are important to keep in mind, here’s why…

You’re putting in a repeat interval with a particular goal. Maybe it’s 20 x 100m and you need to keep a count on strokes. How many strokes are you still taking at number 14? Or, if you’re doing a slightly longer interval and you need to know: what was your average pace for that last 800m effort? Or even need to check if you’ve done 1200m or 1250m of you current 1500m interval. Don’t you hate it when that happens? Swimsense can answer all these questions perfectly, and on the fly.

The first thing you will notice about the Swimsense is the different color modes it uses to display active recording versus a paused state. In the pool, this contrast is easy to spot, even at a glance underwater. In paused mode, the background goes dark with the text taking on a highlighted effect.

The image on the left is running, and the image on the right is paused

A quick note on the different times displayed on the face. The time in the center, in large font, is the overall accumulating swim time, including rest periods. The smaller time above that is either the interval time or the rest time. When swimming, or when initially paused, the interval time is displayed and is marked with an “I#”, where the # is the number of that interval. When paused, the accumulating rest time is marked with a “P”.

The other detail you need to know is the ALT button on the top left of the watch. This button will become your friend for quickly reviewing data on the fly.

In the next photo, you will notice two values below the time; in this case, 1.33 p and 3.7 m/st. The 1.33p is your 100m pace and in this case, it’s 1 minute 33 seconds. The 3.7 m/st is your average distance per stroke on the last interval. The abbreviation may suggest per single strokes, but after referencing the user guide, this distance per stroke value is in “meters per stroke cycle.”

If you toggle through the ALT options, you will notice the numbers below the time change. Below, we see 75 m and 7 st. The 75m is the distance swum on the last interval where 7st represents your stroke count per length (i.e. 25m, 50m or one of the other allowable variations you configured on your Swimsense). Also remember, this stroke count is the number of cycles you have taken per length. This view is particularly useful over the longer intervals where you might need to check if you’ve completed that 1500m or not.

Alos take note of the I1 on the top left-hand side of the display. This represents your first interval. That number will increment as you start and stop the watch to record your swims.

The next screen below shows two more numbers, 3.5 s/st and 33 sw.

The number 3.5s/st represents your stroke rate. Again, you need to refer to your tempo trainer workout card ( to convert between tempo trainer numbers and displayed values. The important detail to keep in mind is that the “per stroke” reading on the Swimsense is a “per cycle” value. 33sw represents your SWOLF score. This is a very useful number for determining the efficiency of your last interval. The SWOLF score is calculated as the sum of the stroke count per length plus time per length. The higher the SWOLF score, the less efficient your last effort was. A good tip is to correlate your SWOLF score with your golf score. The lower the number, the better!

You will continue to press ALT and come across the numbers like this: 10 cal and 1 lps. This is a calories burnt estimate along with the number of laps swum in this interval. Remember, 1 lap is out and back (i.e. 2 lengths). This is a variation on the distance swum theme previously seen.

Another variation on the distance theme is the total distance in the workout. The “W” logo will show you your total distance along with the total calories burnt estimate for your workout thus far.

Now you should have a good idea of the features the Swimsense has available while in the pool to help you along with your set. At a glance, you can get a factual account of your last interval and use that information to motivate the next effort. Swim fast!

- Bryan


Making Sense of Fatigue with the Swimsense™

My name is Bryan Allott and I’m the founder of, a site that looks at using technology and equipment to aide your training. In evaluating gadgets, I try to look for gadgets that embody simplicity and friendliness in ease of use while taking care of the really complex details. This usually requires a healthy mix of innovation and imagaintion on the manufacturer’s part. The Swimsense, in this regard, is the perfect model. Having used the Swimsense to understand pacing and evaluate swim efficiency, I next used the Swimsense on a negative split set to better understand the effects of fatigue and pacing.

The set: 3 x 10 x 100 (various) leaving every 2 minutes. Three 100s in each 10 were to be swum as a negative split; i.e. each length faster than the previous. This was the focus of the set while the surrounding 100s were designed to tax the swimmer (IMs, drills, kicks, fins). The objective: maintain a smooth negative split, working towards building a better finish in races especially when fatigued.

The first group of negative split 100s went swimmingly well.

Each lap was faster than the previous, and at this early point in the set, the objective of putting in a fast finish was being met. The SWOLF score sums up the effort quite nicely and showed me that the last length really was a great finish.

In the chart below, you can also see how clearly a negative split effort differs from my usual pacing effort. The negative split effort is in dark blue, while my usual pacing is underlaid in a light blue. Interestingly, wether I start out hard finish slow, or start out slow finish hard, I end up with more or less the same result; but this is only 100m. If we experimented over 200m, 400m or even 3km, reason (and research and history) tells me that the “go out slow, finish hard” is a much more sustainable strategy.

So what exactly happens after 2km with the negative splits?

Wait a minute? That’s not a negative split at all!

Exactly. In fact, when I underlay a regular effort with a negative split effort, you can’t really tell them apart. Hello, fatigue.

You might think you’re swimming fast (or on pace) while the reality is very different. The difference between perception and reality also tends to grow as fatigue sets in. The more tired you are, the harder you’re think you’re swimming, yet the slower you’re actually going. So, unless you have a dedicated coach giving you feedback on every effort in every swim, there’s no way for you to know just exactly how you are doing.

But with the Swimsense, I can give my swim the best effort possible and then once I’ve showered, warmed up and had a cup of coffee, I can sit down and look back on my swim with a clear mind and evaluate the goals of the set against the performances recorded. Knowing exactly how you’re progressing with your training, and how far you still need to go, will make a huge impact when lining up your next set. It allows you to build on measurable outcomes towards achieving your season’s goals.

But there’s still more. Where is the critical area that needs improvement?

If I take a closer look at the distance per stroke and stroke rate charts, I glean some important clues.

Starting out with a negative split, I can finish strong with just a little over 3m per stroke.

Interestingly, even on the last negative split (fatigued), I can still finish with just over 3m per stroke, whereas with a “normal” paced swim, I consistently get less than 3m per stroke.

The difference between the two comes in with work rate. For a “normal” swim, I’ll turn my arms quicker (but get less distance with each stroke) in order to move faster. However, when I’m focused on pacing, I turnover much slower but get much better mileage with each stroke (hence a lower SWOLF score) in order to move faster. Now if I can only turn over quicker with the same distance per stroke… :)

Knowing all this and monitoring the results, I can take to the pool more condfidently and purposefully armed with knowledge about myself based on fact, and not just on what I “feel” the set was like. Next time, I will look at how to use the Swimsense to monitor progress in the pool while swimming, and not just after the set.