Training watches … with a heart rate monitor

A guest post from David Carlson

This is an update to the article I wrote in October on training watches.

Since writing that article, I did buy a heart rate monitor (HRM). I’m sure that most of you will have seen me with my blue “bra strap” on many evening or weekend CMSC swims.

Here’s what I’ve learned:

• It’s a nuisance to wear, as it has to be just the right tightness. Too tight is uncomfortable, yet it will slip, particularly on a push off the wall, if it’s too loose. This may be less of an issue under a women’s swim suit, but I haven’t gone there: Rob ~already~ teases me unmercifully for just wearing the bra strap, that scurvy dog.
• My HRM does not easily show me my current heart rate during the workout. The heart rate monitor communicates with the watch using “ANT+”, which I think is like Bluetooth, but in any case it does work under water. So if I want to see my heart rate, I need to get both the watch and the hrm out of the water by standing up. Leigh has a Mio Fuse that does read instantaneous heart rate, but it doesn’t record the data for posterity.
• The hrm I have is brilliant at recording your heart rate for review afterwards. When I press ‘stop’ on the watch at the end of the workout, the heart rate data downloads to the watch. Then you can review the results in Strava, or better yet, Garmin Connect.

Here’s an example

This is part of the VO2 max workout we did on Sunday 13 March with Coach Kevin. The set was 4 x {8×50 @ 200 pace +1×200 smooth}. Each round decreased in time for the 50’s. Our lane started at 1:10 per 50m and then decreased to 1:05, 1:00 and 0:55 for each of the three following rounds.

Starting on the left, you can see my heart rate drop down to 100 bpm after the warmup, and then you can count the peaks of every successive 50, with four sets of 8 followed by a flatter 200. The peaks get more muddled as the rest decreases in the later sets. This is probably seen better if you overlay the swim times on top of the heart rate.

In this graph, the gray is the same heart rate as was shown in red in the first graph. The blue shows the times in an equivalent pace per 100m. The scale is ‘backwards’ (to me, anyway) in that the higher numbers are faster times. I was swimming in a range of 40-42 seconds per 50, so averaging 1:20-1:25 per hundred, which matches what you see on the right hand scale. You can clearly see the 8 narrow blocks of each 50, and then the wider band of the 200m. If you look at each 50, you’ll see it has two ‘steps’ in it – the first is the time of the first length, while the second is the time for the second length. Similarly, you should see 8 steps in the 200m. In a separate screen, you can see the detailed times.

So what?

Using an hrm puts you on a huge learning curve, and I wonder if most people lose interest after getting buried with data after a couple of swims.

Luckily, on the internet there are no shortage of experts to tell you their theories. You could spend hours, if not days or perhaps even weeks reading them all.

I’ll come back to the VO2 max example in a minute, but you need to know some basics first. I am definitely not an expert on this, and what you are seeing is the result of my reading articles form doctors, coaches and armchair experts on the internet.

Most sites agree on the heart rate being split into different zones. Some are 6 and some are 5 – I’m showing 5 just because that is the default for my garmin watch. The difference in heart rate zone corresponds to both workout intensity, and to aerobic vs anaerobic workouts. In aerobic workouts, your bloodstream can deliver the fuel and oxygen required to keep the muscles contracting without fatigue. In anaerobic workouts, muscles rely on other reactions to get their energy – producing fatigue and lactate. Sprinters will be anaerobic, while distance swimmers want to stay in the aerobic zone.

There are lots of internet sites that will help you split your heart rate into the 5 categories. To do it properly, you need a doctor, stress tests, and blood work looking at lactate levels. However the internet sites all present various ‘rules of thumb‘ to get an initial estimate.

The table above is based on the simple % of maximum heart rate. There are similar tables using heart rate reserve (the difference between max and resting heart rate). Then there are rules of thumb to calculate maximum heart rate, such as those based on age. Then there are a number of calculators on the internet to calculate your heart rate zones – just google it.

Rather than estimating my maximum heart rate, I can tell you the highest I’ve measured since November is 174bpm for swimming. This was a pace workout swimming broken 400’s, with Coach Kevin and his stopwatch on the pool deck: “Ready… Go”. It’s funny how you try harder when the coach is timing you.

So using 174 as a maximum, and using the % max HR as the method of calculating the zones, then my heart rate zones are:

• Zone 5 90%-100% 156-174 bpm
• Zone 4 80%-90% 139-156 bpm
• Zone 3 70%-80% 121-139 bpm
• Zone 2 60%-70% 104-121 bpm
• Zone 1 50%-60% 87-104 bpm

Yours will be different, and remember that this is only an approximation. The real numbers would need to be determined by medical testing, if you want to go that route.

OK – so now we’ve got something we can start to use as a training aid.

Don’t be ‘that guy’

Don’t be the guy that jumps in the pool at lunch hour and swims a 1500 every day. You’re probably hitting zone 2 and staying there. You spend lots of time in the water, but don’t really get in better shape.

A proper training regimen consists of various types of workouts from all heart rate zones, and the practices that our coaches have set for us can now start to make some sense: VO2 max, threshold, pace and distance all focus on different heart rate zones… and then technique, pull, IM, kick, and efficiency all to help with stroke mechanics. The mix of workouts depends on your goal: general fitness; weight control, sprints or distance/ open water.

OK – so I’ll leave the workout design to the coaches. What do I do with all this info?

The first thing I check when reviewing the workout afterwards is: “did I do the workout correctly?” Going back to our VO2 max example, the idea of VO2 max is that the more oxygen that your body can transport and use, the faster you’ll be able to go over longer distances. This article explains it. Given the time is takes to swim 50m, you can see that Coach Kevin’s workout was akin to what the article describes in the hill workout paragraph. In set 1 and 2, there was enough rest to put in a good effort every 50, but you can still see a pronounced recovery in the intervening time between every 50. You can see the VO2 max part of the workout in the latter half of set 3 & 4. There was no easily visible heart rate recovery between sets, but overall, I successfully kept my times around the same as the first two sets. My heart rate was certainly up in the “I’m trying really hard” range. Mission accomplished.

The second thing I check is: “could I have done it better?”. Here’s an example from a speed workout on May 15. The workout was 6 x {50 fast, 150 smooth, 100 fast, 100 smooth}. Set 3 & 4 were with fins.

You can see in the first 4 bumps that I took off too fast, like I always do, and did not leave enough time in the set to recover. My speed times suffered, so that the ‘fast’ was not that fast, and the ‘smooth’ was not that smooth. Coach Kevin noticed, and his advice was to take a bit more rest on the smooth swims – which you see in the next 8 bumps. The extra rest allowed me to recover more: my fast times were significantly faster and the smooth swim was really the start of the recovery. After an initial false start, I ended up swimming the workout much better – and the swim times (not shown! but available in Garmin Connect) prove it.

 

Should this article change the way you swim?

Not necessarily. My feeling is that the workouts at CMSC are really focused on swimmers who want to improve their race times in 50m-400m distances. If you have different goals, then you may wish to talk to the coaches.

However, if you just want to show up and swim the workouts, then you really don’t need to know about heart rates and zones. The practices put together by the coaches do take care of everything. Just swim.