The term 'sweet spot' refers to an intensity of training that is hard enough to elicit substantial physiological benefit but not so hard as to be unsustainable. It lies at around 90 percent of threshold power. Functional threshold power, or FTP, is typically defined as the highest output you can sustain for an hour.
If you don’t have a power meter (see why power measurement is important), this roughly equates to 95 percent of your threshold heart rate. Note that your functional threshold heart rate is not your maximum heart rate; as with FTP power, your FTP heart rate is the highest that you could hold for an hour time trial.
Training at this sweet spot is more sustainable than threshold work and less time consuming than endurance training, so cyclists can repeat it frequently and see real improvements.
Turbo training session
The video below shows a sweet spot training session that uses a turbo trainer. It was put together by James McCallum, and aims to help you improve your riding speed and burn fat.
Video: Sweet spot turbo trainer workout
Free-form sweet spot session
This workout, and those that follow it, come from Frank Overton of FasCat Coaching.
The 90-minute free-form session involves going out and riding hard.
Start at 95 percent of your threshold power. As you fatigue, let your wattage fall slightly but continue to push. You should accept that your wattage will rise and fall as the fatigue sets in, but at about 90 percent power, you will be riding in the sweet spot.
Look at the data from your ride afterwards. Each consecutive time you repeat this ride you should aim to hold the sweet spot for a longer period – this will eventually increase your threshold power.
When you’re in a group, take longer stints in the front rather than drafting. Do more work, be aggressive. Check your power meter to confirm you are working at around 90 percent – or 95 percent on your heart rate monitor — of your FTP.
If you find your group is holding you back, try to ride with cyclists who are better than you. Don’t be disheartened if this means you have to sit at the back, just know you are bettering yourself.
Riding with stronger riders makes you stronger – often because you are pushing your sweet spot watts. Download your data after each ride and monitor your improvements.
A hilly group ride – two training techniques ticked off in one go!
If you’re fortunate enough to live in a hilly or mountainous region, climbs are an excellent way to train. Try to remain within the sweet spot from the bottom to the top of any climb you do. Remember to keep track of the total time you spend climbing so that you are able to note improvements.
This workout offers more freedom and motivation than structured intervals such as 3x15 minutes. A good example is an 18-minute climb followed by a 10-minute climb and finished off with a 15-minute climb. This provides a good block of solid work in a stimulating format.