Affect-Guided Interval Training

A new twist on familiar format might make your interval workouts more effective by making them more fun

Matt Fitzgerald and Endurance Mastery by MG

Feb 23, 2026

Zachary Zenko is an assistant professor in the Department of Kinesiology at the University of California-Bakersfield. He was educated at Edinboro University, the University of Pittsburgh, and Iowa State University, and his current research is focused on getting more people to exercise regularly. Mostly recently, Zenko developed and tested a new workout format called affect-guided interval training (AIT), where intensity is self-regulated by the exerciser based on feelings of comfort and discomfort.

For this latest study, Zenko recruited thirty moderately active college students to serve as subjects. The AIT workout was a 20-minute interval session in which one-minute efforts at the highest intensity that still felt pleasurable to the individual were alternated with one-minute efforts at the lowest pleasurable intensity. On separate occasions, the subjects also completed a 20-minute high-intensity interval (HIIT) session in which they alternated between 90 percent and 20 percent of peak power, and a 30-minute self-guided continuous exercise session (SELF). All of the workouts were done on stationary bikes.

The HIIT session proved to be the most intense overall, with subjects ranging between 78 and 97.5 percent of maximum heart rate. In the self-guided session, intensity ranged from 70.6 to 83 percent of HRmax, and in the AIT session it ranged from 71.3 to 84.8 HRmax. Physiologically, then, all three workouts were deemed vigorous. But there were significant differences in the subjects’ experience of the different formats. Specifically, “The AIT session was experienced as more pleasant, remembered as more pleasant, forecasted to be more pleasant if repeated again, and perceived as more enjoyable than HIIT and SELF conditions,” according to Zenko.

What’s In It for Me?

For people who want the benefits of intense exercise but avoid it because they find it unpleasant, affect-guided intervals might offer a realistic entry point to a lasting exercise habit As an endurance athlete, you’re already exercising, but affect-guided intervals might deserve a place in your workout repertoire too. Indeed, I myself reinvented the method in the course of preparing for the 2026 racing season.

Devoted readers of this blog will know that I suffered a fibular stress fracture last October. While I was rehabilitating the injury, I bought a Schwinn indoor bike to facilitate my winter cross-training. After completing a couple of easy spins on the new machine to familiarize myself with it, I got on it with the intention of completing a set of ten, one-minute intervals at high intensity. The bike lacks a power meter, so there was no practical way to set objective performance targets, the intervals being too short for heart rate to have any relevance.

Nor was I in the mood to push super hard and suffer accordingly, as I was just beginning the process of rebuilding my fitness. So, I decided to regulate the intervals by feel, aiming for the hardest effort that didn’t suck. After the workout, curious to know if I was onto something, I did some googling and learned there was a name for what I had just come up with. That’s right: affect-guided intervals.

Enjoyment, Autonomy, and Body Awareness

I’ve just shown you one use case for the method in endurance training, but are there others? Yes! Zenko’s study showed that AIT made interval training more enjoyable for exercisers without making it easier. What athlete wouldn’t want to make their training more enjoyable if they could do so without decreasing its effectiveness? In fact, I’ll go one step further: Enjoyment itself improves training effectiveness, so you might even come out ahead fitness-wise by incorporating AIT into your training.

Besides the fun factor, there are two things that, as a coach, I really like about affect-guided intervals. The first is autonomy. Zenko measured subjects’ perceived autonomy after all three workouts and found it was highest in the AIT session, which is unsurprising because the subjects were forced to act autonomously in executing it. This is important because when athletes are supported in their autonomy, they learn more and become better self-regulators, and as devoted readers know, self-regulatory prowess is the essence of sport mastery. Affect-guided intervals put more responsibility on the athlete than traditional ones do, and that’s a good thing.

The other thing I like about AIT is that it requires athletes to tune in to their internal perceptions instead of mindlessly enslaving themselves to external data. Today’s endurance athletes are grossly overdependent on technology, and as a result they essentially cannot feel their own bodies. This wouldn’t be a problem of sports watches could reliably guide athletes to their performance limit in competition, but they can’t, nor will they ever be able to, because our performance limit is defined by internal perceptions.

Athletes need to be challenged to hit performance targets in some of their workouts, but I plan to substitute some of my athletes’ traditional interval sets with AIT going forward, and I encourage you to give them a try. Here’s a sample format to get you started:

10:00 easy
10 x 1:00 at the highest effort that still feels enjoyable/2:00 easy
10:00 easy

Tell me how it goes!