Has LISS Overtaken HIIT The Shift In Modern Fitness

If you’ve followed a fitness influencer or stepped inside a gym in the past decade or so, you’ll be aware: HIIT dominates the fitness. But recently, there’s been a shift, and low intensity steady state training is gaining momentum. Here’s why

For years, intensity ruled the fitness world.

Workouts were designed to be fast, explosive and exhausting. Classes promised maximum burn in minimum time. Sprints replaced jogs, circuits replaced steady cardio, and the phrase high intensity interval training became almost synonymous with getting fit.

But lately, the energy in gyms and on fitness feeds has shifted. The treadmill pace has slowed. The heart rate zones look calmer. Walks are being tracked with the same pride once reserved for brutal interval sessions.

Low intensity steady state training, better known as LISS, is quietly reclaiming space in the fitness conversation.

So has LISS actually overtaken HIIT, or are we simply rediscovering balance? 

What HIIT Promised

HIIT rose to prominence for good reason. Short bursts of intense effort followed by recovery periods were shown to improve cardiovascular fitness and metabolic health in relatively little time.

For busy schedules, the appeal was clear: 20 minutes of intense intervals could deliver similar aerobic benefits to longer moderate sessions.

The format also suited the digital era. Fast paced workouts translated well into classes, apps and social media. The sweatier the better. The harder the session, the more impressive it looked. Strava communities rewarded each other with kudos for “savage” or “brutal” workouts. 

But over time, something else became clear. Not everyone thrives on constant intensity.

The Rise Of LISS

LISS training focuses on sustained, lower intensity activity performed at a steady pace. Think brisk walking, cycling, swimming or incline treadmill sessions. Your heart rate remains elevated but manageable. The kind of intensity where you can (in theory) hold a conversation.

Unlike HIIT, the goal is not maximum effort. It is consistency.

It is easier to recover from, easier to maintain (or indeed find motivation for), and easier to incorporate into daily life. A long walk can be social, calming and restorative in ways that a maximal sprint session rarely is. And for many people, especially those already dealing with demanding work schedules and high stress levels, lower intensity movement feels more sustainable.

The Nervous System Factor

Another reason for the LISS resurgence is growing awareness of how training interacts with the nervous system.

High intensity training activates the sympathetic nervous system, the body’s fight or flight mode. This is not inherently negative, but when combined with chronic life stress it can contribute to fatigue and burnout.

LISS, by contrast, tends to support the parasympathetic state associated with recovery and regulation. Many people find steady movement helps reduce stress while still improving cardiovascular health.

In a culture increasingly focused on nervous system balance, slower training has newfound appeal.

The Fat Burning Conversation

One of the traditional arguments for LISS relates to fat oxidation. At lower intensities, the body tends to rely more heavily on fat as a fuel source.

While total energy expenditure remains the most important factor in body composition, steady cardio can be an effective way to increase daily movement without excessive fatigue.

For those combining strength training with cardio, LISS also interferes less with recovery between sessions.

Why HIIT Is Not Disappearing

Despite the current LISS enthusiasm, HIIT is far from obsolete. High intensity intervals remain an efficient way to improve cardiovascular capacity, speed and anaerobic power.

For athletes or individuals who enjoy pushing their limits, HIIT delivers benefits that slower training cannot fully replicate.

Fundamentally, the issue was never HIIT itself. It was the idea that every workout needed to feel maximal to be worthwhile. If HIIT works for you, keep at it. But try incorporating a few LISS sessions into your training plan for some variety.

The most effective training approach is rarely the loudest. Sometimes the quietest workouts are the ones that last the longest.