LISS cardio vs HIIT: what each one does for you

LISS cardio, low-intensity steady state, is the least glamorous training on the internet. Walk on an incline. Ride a bike at a pace that lets you hold a conversation. Row for 40 minutes without dying. HIIT gets the videos and the before-and-afters. LISS gets the results nobody films.

The honest answer to LISS vs HIIT isn't "pick one". Both improve fitness, they do it at very different recovery costs, and a good week uses mostly one and a little of the other. Here's what each does, the right LISS cardio heart rate, and how to fit both into a plan that balances both sports when you also lift or run.

What is LISS cardio?

LISS cardio is any continuous aerobic exercise done at an easy, steady effort for a while, usually 30 to 60 minutes. Brisk or incline walking, easy cycling, rowing, the ski erg, swimming, easy running. The machine doesn't matter. The effort does: steady, sustainable, and easy enough to talk in full sentences.

In the five-zone model we use on this blog, LISS is zone 2, with the occasional zone 1 recovery day. If you'd rather have LISS slotted into a week for you, our hybrid program does that, alongside the lifting and the hard sessions.

For runners, LISS mostly is the easy running. For lifters, it's usually the bike or the incline treadmill. Either way, it's the backbone of strength and conditioning for distance runners and of most hybrid programs: the work that builds the engine without wrecking tomorrow.

LISS cardio heart rate: where it should sit

The right LISS cardio heart rate is roughly 60–70% of your max heart rate, which is zone 2 in the standard five-zone model you'll find from watch makers like Polar. Recovery sessions sit lower, at 50–60%.

The max heart rate estimate comes from Tanaka, Monahan and Seals (2001). It's a population average, so use the table as a starting point, not a verdict.

Cross-check it with the talk test. If you can speak in full sentences, you're in LISS territory. If you're down to a few words at a time, you've drifted into a harder zone, and that's a different session.

The most common LISS mistake is doing it slightly too hard. It feels more productive. It isn't. It just turns an easy day into a medium day.

What is HIIT?

HIIT, high-intensity interval training, is hard efforts separated by easy recovery. Four minutes hard and three easy. Thirty seconds all-out and a few minutes of soft pedaling. A rotating circuit with a clock running. Effort sits in zones 4 and 5, where you can manage a few words at most.

The formats vary a lot. An AMRAP workout is a kind of HIIT with a fixed time and as many rounds as you can fit in. An assault bike workout plan is HIIT on the most honest machine in the gym. What they share: they're hard days, and they cost recovery.

LISS vs HIIT: what the research says

For aerobic fitness, both work

A meta-analysis of 28 studies in healthy adults (Milanović, Sporiš and Weston, 2015) found both continuous endurance training and HIIT produced large improvements in VO2max, with somewhat bigger gains after HIIT.

The more striking result is how little HIIT can take. In Gillen et al. (2016), sedentary men either did three 20-second all-out cycle sprints within a 10-minute session, or 45 minutes of continuous cycling at about 70% of max heart rate, three times a week for 12 weeks. Peak oxygen uptake rose 19% in both groups, along with similar improvements in insulin sensitivity, despite the five-fold difference in time.

And in moderately trained men, Helgerud et al. (2007) found 4 × 4-minute intervals at 90–95% of max heart rate improved VO2max more than the same total work done as long slow distance at 70% of max or at threshold.

So if VO2max is your only target and time is tight, HIIT is efficient. But that's rarely the whole story.

For endurance athletes, mostly easy wins

Across descriptive studies of competitive endurance athletes, Seiler (2010) found the typical pattern was about 80% of sessions at low intensity and about 20% dominated by high-intensity work. In a nine-week trial in well-trained athletes, a polarized mix (mostly easy, some very hard, little in between) improved key endurance variables more than threshold, high-volume or HIIT-only training (Stöggl and Sperlich, 2014).

That's the case for LISS: not that it beats HIIT session for session, but that it's the only intensity you can do a lot of. Volume needs a lot of easy work. Intensity needs fresh legs. LISS supplies the first and protects the second.

For fat loss, it's closer than the internet thinks

The search bar asks whether LISS or HIIT burns more fat. The evidence is mixed. A meta-analysis in overweight and obese adults (Wewege et al., 2017) found HIIT and moderate-intensity continuous training had similar effects on body composition, with HIIT taking less time. Another (Viana et al., 2019) found both reduced body fat percentage, with interval training producing greater reductions in absolute fat mass.

Two caveats. Those studies compared HIIT with moderate continuous training, which is a little harder than most people's LISS. And fat loss over months depends far more on total activity, food and consistency than on which intensity you picked on Tuesday. Pick the one you'll keep doing.

The real difference: recovery cost

For anyone who also lifts or runs, this matters more than any VO2max number.

Hard sessions compete with each other. Hard intervals the day before heavy squats is a recipe for a bad squat day, and same-session pairings are where the interference research gets loudest: a meta-analysis found explosive strength gains were blunted most when aerobic and strength training shared a session (Schumann et al., 2022). LISS is the cardio that doesn't pick that fight.

That's the core rule of how to combine running and lifting: easy work goes anywhere, hard work gets placed carefully.

LISS for runners, lifters and Hyrox

Runners: your easy runs are your LISS. Extra off-feet LISS (bike, rower) is a way to add aerobic volume without more impact. Your HIIT is your interval session. Don't add more on top.

Lifters: two or three LISS sessions of 30–45 minutes a week is a solid start. After an upper-body day or on a rest day is ideal. Save HIIT for one session a week, well away from leg day.

Hyrox racers: the race is long and sustained, so the aerobic base does most of the work, and most of that base is easy. That's how to train for Hyrox explained in one sentence: build the base with easy volume, then layer station work and race-pace running on top.

Plenty of popular conditioning is HIIT in disguise, however casual the name sounds:

• ›A kettlebell workout routine done as a fast circuit is a hard day. Done slowly and heavy, it's strength work.
• ›A murph workout is a test, not a weekly habit.
• ›Tabata training running intervals are short, but they're not easy. The original protocol was seven to eight 20-second efforts at about 170% of VO2max with 10 seconds of rest between them (Tabata et al., 1996), done to exhaustion.

How much LISS vs HIIT per week?

A simple starting point for someone who runs and lifts:

Count hard runs as HIIT. If you already do intervals and a tempo run, you've done your HIIT for the week, and extra conditioning should be LISS.

How exrsz handles it

exrsz builds a periodized plan from your goal, schedule, level and equipment, with easy aerobic work as the base and hard sessions placed deliberately. It balances running, lifting and conditioning in one plan, adapts each week to how you actually trained, and reshuffles missed sessions so hard days don't stack.

FAQ

What is LISS cardio?

LISS stands for low-intensity steady state: continuous aerobic exercise at an easy effort, usually for 30 to 60 minutes. Incline walking, easy cycling, rowing and easy running all count.

What heart rate should LISS cardio be?

Roughly 60–70% of your max heart rate, which is zone 2 in the standard five-zone model. You should be able to talk in full sentences.

Is LISS or HIIT better?

Neither, on its own. A meta-analysis of 28 studies found both improved VO2max, with slightly bigger gains after HIIT. LISS recovers faster and supports volume; HIIT is time-efficient but costs more recovery.

Is LISS cardio good for fat loss?

It can help, but so can HIIT, and the evidence is mixed: one meta-analysis found similar body composition effects, with HIIT taking less time. Total activity, food and consistency matter more than intensity.

How often should I do LISS cardio?

As often as your schedule allows without it getting in the way of your hard sessions. Two to four sessions a week is common for people who also lift or run.