Training with heart rate vs. training with power - what should you use?
Want to add a new dimension to your training but don't know where to start?
Data-hungry cyclists have never had it so good. Power meters have tumbled in price and are no longer the preserve of pro cyclists, while heart rate monitors are becoming as common on the club run as they are in the peloton.
Becoming a stronger, faster rider is a common goal among many cyclists out there, and turning to data is a common move in a bid to train more intelligently, particularly if you've circled a specific race or sportive in the calendar.
But with the growth in popularity and hype surrounding the virtues of using a power meter weighed up against the benefits of time-tested heart rate training, which should you be using if you want to take your training to the next level? This guide will aim to shed light on training with heart rate and power, and help you decide which is right for you.
Why should you train using heart rate or power at all?
Fundamentally, training with metrics such as heart rate or power output allows you to better understand how hard you’re working at any given moment on a ride.
“Without heart rate or power data, the only measure of fitness or fatigue you have is your Rate of Perceived Exertion (RPE)," says cycling coach Pav Bryan. RPE - or training with 'feel' - is a scale between one and ten used to gauge effort level, from very light activity to max effort activity.
“This is still a viable way to measure your workouts, but can easily be misunderstood or misleading because it’s reliant on how you’re feeling on any given day."
Using your heart rate or power output as data-driven indicators of how much work you’re doing, you can tailor your training sessions to suit you and your goals, whether that's increasing your base endurance or top-end sprint.
"It gives you feedback on your training," says Dan Fleeman, a former professional rider and co-founder of Dig Deep Coaching. "If you’re aiming for an event, and investing a lot of time into it, it gives you a reference for your training.".
As a result, you can maximise the productivity and specificity of your rides when time is short or if you’ve got a specific target in mind, while you can also use data to pace your rides by understanding how hard to work and when.
Training with heart rate
One of the great advantages of training with heart rate is the ability to see just how hard your cardiovascular system is working. By knowing your resting heart rate and maximum heart rate, you can set the training zones on which to base your effort when working on a specific area of your fitness and form.
"Heart rate monitoring has been around for 25-30 years and it’s still a very useful tool," says Fleeman. "For someone who’s looking more at sportives, where it’s longer and steadier efforts in training, or for someone doing time trials, it’s not a bad thing to use at all."
Monitoring your heart rate is also a useful way to see if you’re on the cusp of being ill or if you're overtraining. Key indicators are a higher resting heart rate, while your ability to reach your usual higher limits, or generally control it with your exercise intensity, will be limited.
In short, heart rate gives you an indication of what's happening in your body, while power is the result of that effort.
“Additionally, heart rate monitors can be incredibly cheap, and the data you get back is easy to understand and interpret," says Bryan, "as long as you know your training zones."
- Easy to use & fit
- Easy to understand basic data
- Can be an indicator of fatigue, illness or overtraining
The problem with training with heart rate is it’s not always an accurate indicator of effort.
“If you’re feeling particularly fatigued, ill, stressed or on medication, it’s likely your resting heart rate will be higher, and your maximum heart rate altered too," says Bryan. This means your heart rate training zones are going to be compromised, and you may not be actually hitting the zone you intended, on top of not actually being able to perform at your best.
Heart rate lag can also work against you. Sometimes it can take a minute or two for you heart rate to initially rise to the level you’re aiming for and then stabilise.
"This means for certain periods of time you can be putting either too much or too little effort into your training at key periods, such as short, high intensity intervals," says Bryan.
It's why Fleeman recommends heart rate for long, steady efforts, but, he says, a power meter is a valuable tool if short, intense intervals are an important part of your training.
If you are training for cyclo-cross or criteriums, then you’ll need to do a lot of efforts where you’re going really hard for 20-30 seconds, back off for 20-30 seconds, hard again and repeat that cycle for up to an hour," he says.
"With power, as soon as you press the pedals you get that feedback but with heart rate, because there’s a lag, it makes it very difficult, almost impossible, to use heart rate for really short interval efforts. That’s the biggest drawback."
- Can be influenced by outside factors
- Susceptible to heart rate lag
- Heart rate straps can be uncomfortable
Training with power
Training with power is in vogue at the moment, and that’s primarily because it’s less affected by outside factors and it produces an absolute figure - 200 watts is 200 watts, whereas heart rate can fluctuate based on a range of factors.
"With a power meter, you can see progression," says Fleeman. "With heart rate you don’t see a definite progression, there are a lot of external factors influencing it - heat, altitude, sleep, dehydration - but with power it’s black and white.
"If you invest three months of training and you start off doing 200 watts for a set time, once you’ve put the hard work in, with a power meter you can see that you’re actually improving. It’s certainly good for motivation."
Bryan uses a Functional Threshold Power test to set training zones based on power and, like Fleeman, says using a power meter for training is most beneficial for short efforts.
“Having a power meter is a great way of monitoring your maximal or short interval efforts, because the output you’re generating is clearly visible in front of you immediately," he says.
Unlike heart rate, there's no lag with a power meter, and it gives you a consistent, reliable figure unaffected by external factors - the number of watts displayed on your computer screen is an exact reflection of how hard you're pushing on the pedals.
"As soon as you step on the pedals it goes up, and as soon as you step off the gas the power drops," says Fleeman.
This ensures you're working in exactly the right zones and you can be very specific with your training - and get the most out of it. Also, if you find you can’t generate your usual levels of power, you can objectively work out if it’s because you’re tired, over trained or if some other life event is distracting you from the task at hand.
- Less influenced by outside factors
- More accurate reflection of effort or work
- Enables you to be more specific with training
- Makes motoring progression and fitness easier
While there’s potentially more accurate and representative data to be gained from measuring power, that data comes at a cost to your bank balance. Even if they have dropped significantly in price, power meters remain far more expensive than heart rate monitors, and for this reason they’ve tended to become the preserve of professionals, keen amateur racers and riders with extra disposable income.
While the affordability of a heart rate monitor allows you to dip your toe into training with data, a power meter is a much more significant purchase, and some riders find training with power to be too prescriptive.
"A rigid training plan doesn’t suit everybody," says Fleeman, who also emphasises that it's important not to neglect other areas of training, like technique, whether it's cornering at speed or riding in a group.
"I think a lot of people get into structured training and do really enjoy it but other people don’t and you shouldn’t force them. On the other hand, some people get a bit obsessed with it, too. You don’t want to become a slave to your power meter and some people go too far the other way – they literally don’t stop pedalling on a downhill because they don’t want their power to go down. That’s going too far and you need to find a happy medium."
Fleeman and Bryan also both agree that power data can be difficult to interpret and analyse - and it's the ability to use a power meter to its full potential which will ultimately allow the rider to make the biggest strides forward.
“Power data can be easily misread or misinterpreted, not least because it tends to spike with each pedal stroke," adds Bryan, who recommends Hunter Allen and Andrew Coggan's book, Training and Racing with a Power Meter, as an invaluable guide.
Naturally, both Bryan and Fleeman say a coach can help a rider get the most out of their power meter, and, as coaches, it gives them a cast iron insight into how their riders' training.
"Interpreting data can be complicated and fraught with confusion," says Bryan. "Knowing how to read power data and understand what it means is vital to getting the most out of a power meter."
- Can be difficult to fit
- Data can be difficult to interpret
- Potential for reliability issues
Using both heart rate and power
Ultimately, it needn't be a case of one or the other, and heart rate and power can be used side-by-side to track all your training and progression, and to monitor your fitness and fatigue.
“I believe that if you have a power meter, you should also heart rate monitor too," says Bryan, while Fleeman also advises his coaching clients to wear a heart rate strap alongside using a power meter.
Bryan adds: "A perfect example of this in action is, depending on where a rider is in their training cycle, a 300-watt effort may be easier to produce on one day than another. So, using a heart rate monitor can help athletes understand what’s happening in the body [in terms of fatigue] with that effort of 300 watts."
While a power meter may provide more accurate, real-time training data, Bryan believes it shouldn't be used in isolation and, in fact, it's when using both a power meter and heart rate monitor in tandem that you get the most valuable picture of what you're doing on the bike.
"Without using heart rate or accounting for how you’re feeling it would be difficult to understand why it is you’re able to produce figures on a given day," Bryan adds.
"When advising coaching clients, I like to give repeatable sessions so that we can see their progression and what their bodies are doing in power for any given heart rate (or vice versa). You can introduce benchmarks like three-minute aerobic, 20-minute Functional Threshold Power or incremental ramp tests to set training zones and accurately monitor progression.
“Also, as you approach your target event you can tailor your training sessions to replicate the stresses of that event. That means you can really train specifically for the power you need to climb that hill, bridge that gap, complete that 10-mile time trial and so on, while matching this up with your heart rate to ensure you’re not overtraining."
What's right for you?
These days, the most highly regarded and fashionable way to train is with a power meter - pros love it for the immediacy of data output, and how accurate it is down to the individual pedal stroke, and amateurs love it because, well, the pros do.
However, while Fleeman and Bryan both agree that a power meter is an invaluable training tool when used correctly, it doesn't mean you're not able to train effectively without one.
“I’d argue that most training sessions done with power can be reliably done with a heart rate monitor, except maximal or short intervals where your heart rate takes too long to respond to the given effort, in which case using RPE to gauge effort is the most effective method," Bryan says.
Bryan, who recommends performing a maximal heart rate test to set training zones based on heart rate, says some riders strike the balance by training with heart rate, then undergoing regular testing, whether it be at the gym, on a WattBike, or with a coach, to back that up with power data.
For amateur riders, owning a power meter full-time means more than trying to hit the biggest figure possible, and in order to get the most from the device, it takes commitment on behalf of the rider.
Ultimately, Fleeman says, the discipline and structure required to use a power meter effectively depends on the individual rider and their goals - some riders thrive on numbers and a training plan, and will see the fitness gains to match, others want to 'just ride' and enjoy the form which comes as a result of that.
"If you do want to improve, then getting a power meter is a big help," he says. "But if you’re the sort of person who doesn’t want that structure and just wants to ride for fun then that’s different and it's not a worthwhile investment. At the end of the day, you’ve got to use it as a tool to give you feedback and help you improve what you do - if that's your goal then a power meter is invaluable."