Functional Threshold Testing - Heart rate and Power

Bike Test - If you only have a Heart Rate Montior

Functional Threshold Heart Rate (or FTHR) is the heart rate you can sustain for a one hour race effort. We use this heart rate as a physiological marker, from which we can work out certain zones with definite training purposes. For accurate heart rate based training, the first step is to accurately measure your functional threshold heart rate.

If you have a heart rate graph from a one hour race (like a cycling time trial), your heart rate average over the hour is your FTHR.

To test in training it's too hard to do an hour alone, so we use a 30 minute all out effort -  ideally on a turbo trainer. Your FTHR is the average heart rate for the last 20 minutes of the test. We can simply highlight the last 20 minutes of the test in the trainingpeaks software, and it will tell us the average over the last 20 mins. ( see our  trainingpeaks help videos section for more information.)

An ideal ride will have you riding at a constant speed through the whole test. This will 'feel like' an increasing effort, and be very taxing for the last ten minutes.

Bike Test - If you have a power meter

The good news is that the test is exactly the same! The only difference is that afterwards, when we look at the power data, your Functional Threshold Power (FTP) is the average power over the full 30 minutes. Again, we're assuming that you've held a consistent power through the test. Wear your heart rate monitor as well, as this information will be valuable to your coach as you do analysis.

Some coaches use different test durations, but over several seasons, we've settled on doing the test over a 30 minute period, as the results correlate almost exactly with the wattage that an athlete can put out on the road over an hour.

How threshold 'feels'

It's worth noting that most people can 'feel' Functional Threshold quite accurately, even without a heart rate monitor. It's that feeling of 'if I go a little bit harder, I'm going to have to stop exercising a whole lot sooner.'

However, in a race situation, when we're excited and our body is full of adrenaline, it's often hard to 'feel' things accurately. Similarly, in training, on your own especially, a heart rate monitor can be a useful tool to let you know that you should be working a bit harder in order to get the training effect you're after!

Powermeters can be very valuable in racing as the numbers never lie. With heart rate monitors, they often don't tell the whole story. They're affected by dehydration, tiredness, fatigue, whether you slept well, and most critically - excitement. The adrenaline of a race can make the numbers do funny things. You can see higher numbers than usual, yet feel great.