We are regularly asked in both the bike shop and through our coaching should I train using power? In my opinion the answer for most people is no (it’s important to remember that I’m also selling power meters, so there’s a potentially large sale at the end of a yes answer) despite this the answer more often than not is still no.
But why am I reading everywhere that training by power is the most effective and efficient method of training?
I’m not for one minute saying it isn’t efficient and effective. What I’m saying is that it’s not necessarily the right tool for most athletes.
So how do I know if I’m better off with or without a power meter?


I believe that there are a couple of questions that you should ask yourself if you are wondering should you train by power.

1.The first is do you know anything about how to use the numbers that the power meter will give you?

If the answer is no then the next question is

2. Are you willing to learn how to use it?

If the answer is still no then your next question is…

3. Will you employ a coach or mentor to test you to establish your zones and set your training plan based on power?

If the answer is still no then you shouldn’t buy or don’t need a power meter. If you do buy one you are simply buying a €1000 ornament for your bike. If you would like a €1000 ornament for your bike then I can certainly sell you one of those but there are prettier bike ornaments to spend your money on than a power meter.

If on the other hand you’ve answered yes to the above questions and you either know how to set your zones and are going to build sessions based on those zones (or will use a coach to do it for you) then you can move on to the next question.

Related: How to train for an Ironman

Will you do what your told to do? If the sessions requires that your long Sunday ride is all done in zone 1 and 2 will you allow yourself to be dropped by the rest of your regular training group as they ride hard on the climbs or if the pace goes up on the flat as they ride up and overs?

This question is important and must be answered truthfully. If the answer is no, then again you are better off keeping your money in your pocket rather than shelling out for that power meter. Otherwise you will get as much value as if you stick your €1000 in a hole in the ground.

It’s not that I think training by power is a bad idea. Rather it’s that I don’t think it’s suitable for all recreational cyclists or triathletes. The enjoyment for a lot of athletes in the Sunday club ride is racing for the top of the climb or the speed limit sign at the edge of the next village. That enjoyment means that they get out and ride, it’s their motivation to train, it’s what gets them out of bed and out the door when the weather isn’t good. It’s what keeps them training.

If you’re not going to do what you’re told and instead just go out and enjoy riding your bike then again, don’t buy the power meter.

Related: How to train to do a faster Ironman

What about using heart rate?

I think all of the same criteria apply. It’s only suitable if you are either going to learn how to use it or get someone to test you, set your zones and then you must also be disciplined enough to do what you’re told by that little heart rate strap on your chest and the watch on your arm.

Metrics as a form of communication or control.

One area where a power meter or heart rate monitor is useful is in communication between the coach and athlete. It does away with any ambiguity. 200 watts is always 200 watts, a heart rate of 140 bpm is always 140bpm.

Where what feels like easy to me might be uncomfortable to someone else. What I call a 7/10 effort someone else might call 5/10

Having an unambiguous form of communication between coach and athlete will result in better results.
Metrics as a means of measuring progress and establishing if your training methods are effective.

Of course you can also use a power meter to measure your improvement but there are cheaper ways. Riding a time trial on the same course each month for example.
Why you need to combine two metrics.
As good as any of these tools are they all have limitations. Heart rate can be affected by a lot of external factors that can skew the numbers. For example stress, having a lot of caffeine before going out for a ride, or being tired.

Power similarly has it’s limitations. If you’re tired and are supposed to hit a certain number for your intervals and all you base the session on is those numbers then you will most likely go too hard.

If you are training by power it’s best to do so in conjunction with heart rate. If your heart rate is way off for a given wattage then you know that you might need to back off and instead of a hard session just do an easy one instead.

It’s important to remember that these are all of these are just measurements of your work. There is no one right answer as to which you should use and they are not magic bullets. Buying a power meter or heart rate monitor will not automatically make you faster.

A disciplined athlete who enjoys the very scientific and numbers based approach will very often work better when they train with combined power and heart rate. They can feel like their training is more specific, more exact and as a result will produce better results.

An example of a “numbers athlete” is a good friend and training partner of mine Cillian Moffat. Cillian is probably the best example of why the numbers matter but that the type of measure doesn’t.

Cillian discovered Phil Maffetone and what is called the “Maffetone Method” a couple of years ago and bought into the principles Phil teaches. Phil’s idea is to focus the largest part of an athletes training in what he calls zone two. He also gives the metric to calculate your heart rate zones. Maffetone focuses on your aerobic zone and for most athletes feels quite easy.

Once Cillian decided on a way forward he set his zones and with metronomic discipline he followed Maffetone’s training principle like his life depended on it. For months he trained alone so that he wasn’t dealing with the problems that group training present when you’re trying to do something very specific to yourself. The trust he showed in following the plan was rewarded with one of the most impressive debut Ironman seasons I’ve ever seen.

He was on the podium in every middle and full distance race he did including Ironman UK, Ironman Wales, Ironman 70.3 Dublin and the Challenge Half in Galway. If his collection of perspex MDot trophies isn’t enough to impress you then the fact that he qualified for the Ironman World Championships in Kona, the Ironman 70.3 World Championships and the new Challenge Championships in Poland all training almost exclusively in zone 2 probably should. And he did it all without the benefit of a power meter.

This season, 2017, Cillian has switched to training using power as well as heart rate and because of his incredible training discipline he is the perfect athlete to use it. This year his coach sets all of his bike sessions using either heart rate or power or a combination of the two and again he just does exactly what he is told.

Cillian didn’t need to use a power meter to qualify for Kona. He needed to train in a consistent and disciplined manner. He now feels that using power will improve his training this year by adding a higher level of accuracy but this only helps if you have the discipline to do what that little computer tells you to do.

The drawbacks of training with power and how to overcome them.

Power like all training metrics has it’s downside or limitations. These include but are not limited to the following.

1. 100 watt’s is always 100 watts regardless of whether you are feeling good, bad, tired or fresh. This makes training by power very accurate but it can also make it wildly inaccurate. The problem with aiming for a number while training for Ironman, triathlon or cycling is that some days you feel great and some days you feel rubbish and this can have as much to do with what’s going on in your life outside of training as what sessions you’ve done this week. It can of course also be a result of a heavy or light training load. Anyone who’s ever ridden a bike knows that some days you just have magic legs and can ride anyone off your wheel and the following week you are hanging off the back of the group. Power doesn’t allow for these good or bad days. If you’re lucky enough to have magic legs on race day a power meter will constrain you and limit your performance. Conversely if for whatever reason you are struggling a little on race day then trying to hit a pre designated number will most likely fry your legs.

– If you try to stick rigidly to hitting an arbitrary number in a training session it may mean that you have an excellent session but it may also mean that you tip yourself over the edge if you are close to your physical limit. The number on your computer doesn’t allow for anything other than what’s happening at the pedals. It doesn’t know if you’ve had three hours sleep, are recovering from a bug or head cold or are in the early stages of one and maybe don’t yet know. If by aiming for a number just because it’s in the plan you may do more damage than good.

When I was training for Kona in 2013 I like a lot of athletes who I qualified at a late Summer race had a very short window to rest, recover, train and then taper for Hawaii. As a result I spent quite a bit of time right on that razors edge of over reaching

Related: Over reaching & over training

Some day’s I’d be flying but some days it was enough stress on the body just to get time in the saddle. I’d often make a call an hour into a ride that this wasn’t the day to do any intervals but that getting four hours of steady riding was ok. Knowing when to ignore the numbers and go on how you feel is a big part of learning how to train. And just because you aren’t hitting the numbers doesn’t mean that you pull the plug and go home. It often just means that you log the time in the saddle but at an easier effort.
Combining HR and power

When you combine two or more metrics is often when you really see a significant improvement in training. By using both heart rate and power as a measure of your effort and how your body is coping with it you can really start to make the most of power as a metric.

For example if you are down to do a 90 minute session with 6 x 5 minutes at threshold and you know both what your threshold power and heart rate are then if for example your heart rate was much higher than normal and you couldn’t reach the target power you would know that maybe you’re fatigued or ill and that pushing to reach the power number is a bad idea. If you were only using power you wouldn’t necessarily realise this as quickly.

Working with both power and heart rate is also a good way to see and measure improvements. If you are putting out 200 watts at a given heart rate and one month later when you test again and your power is up at the same heart rate then you know definitively that what you are doing is working.

Another problem with racing by heart rate or power is that you can become too reliant on that little screen. If you exit T1 and for whatever reason it doesn’t come on you may be in big trouble if you rely on it as your way of controlling pace. You would essentially be riding blind without probably the most important metric needed for IM, a way to measure your pace particularly at the start of the bike when most of the pacing mistakes happen.

Learning to train and race using perceived effort does away with these issues. Hard always feels hard, easy always feels easy. When you learn just how easy it should feel in the first hour of an Ironman bike and conversely how hard it feels in the last hour at the same power output or speed then you can pace an regulate your effort without relying on any external tools but this must be learned in the same way as you would learn how to train using a power meter or heart rate training.

Chasing Kona eBook available

From smoker to back of the pack triathlete to the Ironman World Championships.

Read about how I overcame all of the odds and discovered what it would take to get to the Ironman World Championships – my eBook is now available to buy on Amazon UK and Amazon US.