Are Sweet Spot Cycling Sessions Better Than Threshold Workouts?

Published October 27, 2021 07:00AM

It’s a question asked by many, from first-time riders to experienced professionals: Are sweet spot sessions or threshold workouts more effective for improving cycling fitness? Cycling coaches, scientists, and physiologists seem to come up with new training protocols every few years; but are the ones we have now actually better than what we had before?

The advancements in training efficiency have certainly improved over time, and you can now find amateur cyclists with 350 watt FTPs who train 8 hours per week. How do they do it? A mix of high-intensity intervals, structured training, and effective rest periods.

There are many different training philosophies to choose from, and sweet spot training has become one of the most popular. Threshold training is now a more traditional, old-school-style that few riders use, even though the benefits are there. In fact, when you dive into the science, you may be convinced to give threshold training a try. In this column, we’ll be diving into the similarities and differences between sweet spot and threshold training, and help you find out which style is best for you.

Defining sweet spot and threshold training

According to Frank Overton, the founder of FasCat Coaching and creator of the term ‘sweet spot,’ “the Sweet Spot is located between high Zone 3 and low Zone 4: between 84-97 percent of your FTP.” Using a five-zone training model, the sweet spot is a sub-threshold effort. It’s enough to elicit a significant physiological training response, without putting us into the red zone.

Using more than just power and your Functional Threshold Power (FTP) — the average power output that you can theoretically hold for an hour — we can define sweet spot in a few different ways. According to Rate of Perceived Exertion (RPE), sweet spot intervals should be completed at 6-7 out of 10, and at 75-85 percent of your maximum heart rate (HRmax). In plain English, sweet spot can be described as, “comfortably uncomfortable,” or “hard but sustainable.”

Threshold training, on the other hand, is done at an 8-9 out of 10 on the RPE scale, and 85-95 percent of HRmax. This corresponds to 91-105 percent FTP, and Zone 4 in the five-zone training model. While only a few percentage points above sweet spot training, threshold training can feel exponentially harder because it is pushing the boundaries of your aerobic threshold, which is where blood lactate begins building up at a rate faster than your muscles can clear it. This is when your legs and lungs start to burn, and your legs start to feel like they’re running on empty.

Most threshold workouts use interval lengths of 8-20 minutes and have enough sets to total 20-60 minutes of time at threshold within the session. Beginners should shoot for 3 sets of 8 minutes at threshold, while better training and more experienced riders can challenge themselves with three 20-minute threshold blocks during a workout.

Sweet spot intervals are typically longer than threshold intervals – a typical sweet spot workout consists of multiple sets of 12-60 minutes at sweet spot (84-97 percent FTP) – and they can stimulate a number of significant physiological adaptations such as:

All of these metrics have a huge effect on cycling performance, but there are also a number of limits to sweet spot training. With so much time spent below your FTP, which is the target of threshold training, you will miss out on a number of short-duration power efforts such as sprints and explosive anaerobic efforts.

In addition to the benefits of sweet spot training, threshold training can also lead to:

These additional physiological adaptations can help increase your sprint power and maximal anaerobic output, as well as increase your lactate threshold, VO₂ Max, and overall fitness.

It seems as though threshold training is the clear winner. Greater benefits from one type of interval over the other. But it’s not as simple as that. There are a number of other considerations with sweet spot and threshold training that can affect your recovery, longevity, and even your mental health.

The good and bad of sweet spot training

The number one reason that cyclists choose sweet spot training is that it is repeatable and sustainable. Your body can recover faster from sweet spot training than other forms of high-intensity interval training (HIIT) such as threshold, Tabatas, or VO₂ Max intervals, which helps you build your fitness faster over a long period of time. According to Overton, “the underlying principle of sweet spot training is a balanced amount of intensity and volume.”

While threshold training can be extremely taxing, both physically and mentally, sweet spot training is manageable so that you can repeat it multiple times per week, and sometimes day after day. With sweet spot training, you can complete more intervals, increase your training load, and increase your cycling performance in less overall training time. The benefits of sweet spot training are numerous, as outlined above, and many riders have been able to increase their FTP by five percent, 10 percent, or even 20 percent using sweet spot training alone.

However, sweet spot training can be dull and boring. During sweet spot intervals, you’re basically pedaling ‘kind of hard’ for anywhere from 20 minutes to an hour. There are no variations in pace or things to think about, you’re just sitting at prescribed power output and focusing on keeping a steady effort. Anecdotally, I know many athletes who have become burnt out on sweet spot training because of the mental aspect alone. As competitive cyclists, we want to challenge ourselves, feel the burn, and race as fast as we can whether it’s for a Strava KOM or the national criterium championship. By nature, sweet spot training is very limiting, and it leaves you feeling like there’s something missing.

The good and bad of threshold training

Threshold training includes all the same benefits of sweet spot training and then some – so what’s not to love?

To start, threshold training is exponentially harder than sweet spot training as you approach and then exceed your FTP during targeted intervals. There is simply more physiological and psychological strain on the body during threshold intervals versus sweet spot intervals, enough so that it is impossible to fully recover from a threshold interval session in less than 24 hours.

Cyclists choose sweet spot training because it is sustainable and repeatable, whereas threshold training is so hard that it can/should only be done once or twice per week. Because you’ll need more time to recover between threshold training sessions, you won’t be able to train as much in total, or complete as many high-intensity intervals compared to sweet spot training. Thus, your overall workload will be lower, and your fitness won’t be able to reach the heights it is capable of with sweet spot training.

How to choose between threshold and sweet spot workouts

It is important to point out that both sweet spot and threshold training work. Both types of intervals stimulate different – and sometimes overlapping – physiological training effects, as well as carrying different loads of fatigue. When it comes to choosing between one or the other, it really depends on what type of rider you are.

Sweet spot intervals are better for building your FTP from the bottom up, sustainably increasing your overall fitness over a long period of time. For gravel riders, stage racers, or cyclists looking to complete their first century, sweet spot training is the way to go. You’ll get the most out of your training using sweet spot intervals, and continually build your fitness on the way to reaching your goal.

Threshold training is great for crit racers, time trial riders, and track cyclists because of its focus on high-intensity training coupled with longer rest periods. While gravel riders and road racers need sustainable power for hours at a time, track riders and crit racers need short bursts of super high-intensity power for less than an hour. The additional benefits of threshold training versus sweet spot training – such as increased neuromuscular power and hypertrophy of fast-twitch muscle fibers – will be of great benefit to these styles of riders who focus on short and explosive power outputs.

Like many of the hottest debates in cycling – disc brakes vs rim brakes, or tubeless vs clinchers – both options work. What matters the most is that you commit to your choice and execute it to the best of your ability. Whether you pick the sweet spot approach or threshold training, make sure you create a structured training plan that balances fatigue and recovery so that you can get the most out of your training, and you’ll be well on your way to reaching your cycling goals.