Tackling a triathlon: Speedo swim coach Dan Bullock on wearables and training

We get an expert's point of view on how useful wearables can be for the swim leg
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It's just a couple of months until Team Wareable takes on the AJ Bell London Triathlon (the relay version, that is). Executive editor James is on running duty, resident bike-lover Conor will be taking the cycling leg and I'll be pulling on my wetsuit and getting into the water for the swimming.

I'm a pretty confident swimmer in the pool and can cover the distance I need to do on the day, but I know full well that it's a different ball game when you're in the water, where there are no lanes to keep you from covering more distance than you need and there are a whole lot more people in water to contend with. I've swum in what felt like freezing cold temperatures at Hampstead Heath's ponds and taken a dip in Hyde Park's Serpentine lido in the scorching sun, and I know full well that there's still some training that needs to be done to make sure I'm where I need to be for my leg of the relay come race day.

Essential reading: Best sports watches to own right now

It's part of the reason why I've sought out some help and advice from someone that knows what it takes to get that open water swim done right. Dan Bullock is a fully certified swim coach for Speedo and has worked with triathletes of all levels. He also has plenty of personal accolades to make him an ideal man to talk to. He's been National Masters Openwater champion since 2008, has a European Masters medal to his name and competed in several Ironman triathlons, having swum 3.8km in just under 45 minutes.

Along with getting some useful advice on what I need to do to prepare for that day in August, I also wanted to get Bullock's thoughts on the role of wearables for triathlon training and racing, how well suited they are to the sport and how to make the most of the data that they dish out. But before we got into that, I wanted to know about his first experiences of using wearables for swimming.

"My first watch was a Polar from the late 90s when I raced triathlon more seriously after a long swim career," Bullock tells us. "This was before I started coaching. HR zone training was gaining traction and a King Cycle test and HR monitor would help me plan HR zones for rides and running.

"Later, V02 max tests became more accessible, rather then just for elite competitors in Labs, which meant accuracy improved. Getting accurate readings was not easy and frustrations were high. Measuring HR in the water can be trickier for several reasons – the chest straps would flap around and move and there would be issues with the conductivity. Readings would be hard to decipher since you would be measuring a mix of work being done and for more inefficient swimmers the excess drag being created."

Tri-friendly wearables

Tackling a triathlon: Speedo swim coach Dan Bullock on wearables and training

With Garmin, Polar and Suunto now all offering dedicated triathlete modes on their top end watches and smartwatches, including the Apple Watch, also trying to appeal to lovers of the multi sport event, there are more options now than ever before for triathletes. Serious athletes may well question whether smartwatches are equipped or built well enough for race day training, but Bullock's go-to wearables suggest they can have their place alongside the triathlon-friendly sports watches.

"It's the Apple Watch for everyday swim/bike/run set up with Speedo On and the Vitality Health system," Bullock says. "Last summer I used a Garmin to track most of my long swims and races (Lake Geneva relay, 24km, the Dart 10km). I am a late convert to using them regularly, I now love the accountability they bring when you don't necessarily have a coach overseeing your own training.

"I now swim a lot more, since I track weekly distance, average pace and swim economy scores. Bringing my heart rate down during a long run while maintaining or lowering my average KM pace is also key as I add more running. Stats make the training more relevant and more interesting. It is harder to leave a session unfinished when later you will have the cold, hard facts staring you from your laptop having logged into SpeedoOn and tracked the session."

While running and cycling seem to be the biggest beneficiaries of developments in the wearable tech space, Bullock believes that what is now at swimmers' disposal means the sport – and how it can be monitored and measured – has come a long way, and there are features that he can now rely on. Particularly from the wrist.

"The swim distance tracking ability from the wrist has improved tremendously compared to the old days, when we would attach watches to goggles on the back of heads since the arm movements back and forth were confusing things," he said. "This makes life easier, especially when I am coaching since 3-4 lanes of up to 30 people who will have slightly different sessions and amounts completed. Swimmers helping monitor their own stats can make my life easier as a coach.

"Personally, mapping routes and reviewing can be of use to see how well I tackled a course. I was quite proud of only adding 79m to the 10km event in the River Dart last year. Adding distance unnecessarily is wasted time, energy and losses to competitors."

When it's time to turn to coach mode, Bullock tells us that the most common tech he sees are watches and swim metronomes that beep to a swim speed to help swimmers find their pace or stick to a faster pace in training.

"Most watch data needs to be interpreted once you finish a swim block in-between lengths, which is okay for pool training but has its limitations," he tells us. "There are some tagging systems that track your movements accurately while you swim but again you read the data later. Sometimes swimming needs the watch to be left on the poolside, as they can be distracting while concentrating on technical work, so all have pros and cons."

Swimming metrics that really matter

Tackling a triathlon: Speedo swim coach Dan Bullock on wearables and training

While there's an acceptance that wearables built for swim tracking have improved vastly in the way they can accurately monitor performance both in the pool and open water, that is only one piece of the puzzle. Like tracking runs or cycles, it's really about getting to grips with the data these wearables and trackers dish out. Which metrics matter? How can you put them to use? Bullock feels there are a couple that stand out for swimmers.

"SWOLF or any swim economy measurement is useful," he tells us. "A popular metric is adding the time taken per 25m to strokes taken over the same distance. Attempting to lower this value can help you monitor your swim technique. Reduce one at the expense of the other and the total will stay high.

"Distance covered is another. Knowing I am confident of achieving and completing a previously never achieved distance is important. If the London Tri is your first attempt at a 1500m swim you should be confident of being able to complete this distance plus 10% for contingencies."

Tracking HR is useful to help quantify your swim especially if you are on a recovery swim and need to keep it easy ahead of a hard bike or run later

Heart rate monitoring is commonplace in running and cycling training, and has its place in swimming too. That's mostly through the use of heart rate chest straps, simply due to the fact that water is a big obstacle for measuring heart rate in the pool or the sea. Wearables that lie away from the chest and promise accurate readings are starting to emerge, like Scosche's Rhythm24 armband. But is heart rate a useful metric for swim training?

"It can be very useful to observe," says Bullock. "Water is a tricky medium to work with and your swimming technique can have its good and bad days. Some days it feels dreadful but is fast, sometimes your timing clicks and it feels easy but delivers some less speedy results. Tracking HR is useful to help quantify your swim, especially if you are on a recovery swim and need to keep it easy ahead of a hard bike or run later.

"Back in the 80s one of my swim coaches had an early attempt at a HR monitor where two sponges attached to wires would be put on the chest. He was keen on personalising training and allowing you to rest and recover down to a reduced HR which was interesting. Up to this point a lane of swimmers of similar ability would rest for a time period for the lane, meaning the session would be harder or easier for some and not at all unique to the specific swimmer. Be careful of this if training in a club environment where the lane is coached rather than the individuals."

Building that dream swim wearable

Tackling a triathlon: Speedo swim coach Dan Bullock on wearables and training

As alluded to in our Wareable 50 tech predictions for 2018, swimming is still ripe for truly groundbreaking innovation, and with talk of smart swimming goggles and incoming smartwatches from Samsung, Apple, Garmin and others to look forward to, there's definitely more to come in 2018 and beyond.

But what if you had all the resources at your disposal to make a wearable that was built for the water? What would that look like? What would it track?

"When it comes to swimming we are limited with how we engage with wearable tech," Bullock tells us. "We can look at it or hear it but water provides for a hostile environment. We also, ideally, need it to be streamlined – especially in racing. Audible devices could help with technical instructions and metronomes have proved useful for pacing. Visual repetition of technical skills have appeared on special videos/goggles which neuroplasticity suggests we can use to improve our ability to perform a new skill.

"HR levels have been flashed to us via a lighting/colour system on a special pair of goggles. So far, all have been clumsy and bolt ons rather than sleekly integrated. At some point a head ups display in the goggle will be done really well, as I see that being the least intrusive to your swim technique. Pace, stroke count, distance covered, HR, countdown to finish line in a race, compass or mapping function to finish or the next buoy, water temperature could all be of definitely be of use here."

Thanks to Speedo for getting us time to talk to Dan Bullock for this piece.

How we test

Michael Sawh


Michael Sawh has been covering the wearable tech industry since the very first Fitbit landed back in 2011. Previously the resident wearable tech expert at Trusted Reviews, he also marshaled the features section of T3.com.

He also regularly contributed to T3 magazine when they needed someone to talk about fitness trackers, running watches, headphones, tablets, and phones.

Michael writes for GQ, Wired, Coach Mag, Metro, MSN, BBC Focus, Stuff, TechRadar and has made several appearances on the BBC Travel Show to talk all things tech. 

Michael is a lover of all things sports and fitness-tech related, clocking up over 15 marathons and has put in serious hours in the pool all in the name of testing every fitness wearable going. Expect to see him with a minimum of two wearables at any given time.

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