HIIT for Over-65s: What a New Six-Month Study Found

HIIT can be a good option for many healthy people over 65: in a six-month Australian trial of 123 adults with an average age of 72, every exercise group lost a little fat, but only the high-intensity interval training (HIIT) group held on to its lean mass. That matters for everyday exercisers because keeping muscle as you get older helps with strength and getting about, although the volunteers were healthy and supervised, so the safest first step is a chat with your GP.

The study was led by exercise physiologist Dr Grace Rose at the University of the Sunshine Coast (UniSC), working with the University of Queensland. It was published in the journal Maturitas and has been back in the headlines this October. Below, we explain what the researchers did, what the results do and do not show, and a gentle way to try intervals if your GP is happy for you to.

What did the new HIIT study actually find?

The researchers recruited 123 healthy older adults from the Greater Brisbane area. Their average age was 72 and their average BMI was about 26. The work was part of a larger randomised controlled trial, which means people were put into a group by chance rather than picking their own. That makes it a fairer way to compare different types of exercise.

Everyone trained three times a week for six months, in supervised 45-minute gym sessions, with the effort set using each person's heart rate. There were three groups:

• High-intensity interval training (HIIT): short bursts of very hard work, where breathing is heavy and chatting is difficult, separated by easier recovery.
• Moderate intensity: steady, continuous training at a moderate effort.
• Low intensity: a gentler group that acted as the comparison.

Body composition was measured with DXA scans, a low-dose X-ray scan that splits the body into fat, lean tissue and bone, at the start, after three months and after six months.

All three groups lost a modest amount of fat. Dr Rose summed it up by saying the three intensities all “led to modest fat loss but only HIIT retained lean muscle”. The moderate group reduced fat mass too, but also saw a small dip in lean mass. The HIIT group was the only one whose body fat percentage improved overall, and both the high and moderate groups improved the fat carried around the middle. The researchers say the low-intensity results need further analysis.

Why does keeping muscle matter after 65?

Most of us gradually lose some muscle as we get older. The UniSC team point out that this loss can chip away at strength, mobility and independence, and that it is linked with a higher risk of falls and some long-term health conditions. So a way of exercising that trims fat without trimming muscle is genuinely interesting.

It also shows why the number on the scales does not tell the whole story. Two people can lose the same weight, but if one loses mostly fat and the other loses fat plus some muscle, the first has kept more of what helps them climb stairs, carry shopping and get up from a chair. That is why this study looked at body composition, not just weight.

What does this study not show?

It is a useful study, but it is easy to read too much into a headline. Here is what to keep in mind:

• The volunteers were healthy. The results may not apply to people with heart conditions, joint problems, frailty or other health conditions.
• It lasted six months. We do not know what happens over several years, and the authors call for more research on long-term outcomes.
• The differences were small. In the paper, the authors say the HIIT group's changes were small and may not be clinically meaningful compared with lower-intensity exercise once measurement error is taken into account.
• Lean mass is not the same as strength. Lean mass on a DXA scan includes muscle but also water and other tissue, and the study measured body composition rather than strength, balance or everyday movement.
• The sessions were supervised. Staff were on hand and heart rate guided the effort. Doing hard intervals alone at home is a different situation.
• Moderate exercise still helped. The moderate group lost fat and improved their waistline too, so steady exercise is far from wasted.

The fair takeaway is this: if you are healthy and your GP agrees, adding some harder intervals may help you hold on to muscle while you lose fat. But steady exercise is still valuable, and the best plan is the one you will keep doing week after week.

What does HIIT actually mean when you are over 65?

HIIT sounds intimidating, but it does not have to mean sprinting or jumping. In this study, the hard parts were short bursts where breathing gets heavy and talking becomes difficult, followed by easier recovery. What counts as “hard” is personal. For one person it is a jog, for another it is a brisk walk up a gentle hill.

Low-impact ways to do intervals include:

• Brisk uphill walking, outdoors or on a treadmill with a slight incline.
• An exercise bike, pedalling harder for 20 to 30 seconds, then easily.
• A rowing machine or cross-trainer at the gym.
• A few faster lengths in the pool with easy lengths in between, if you are a confident swimmer.

If you want more ideas that are kind on the joints, our guide to low-impact cardio for beginners has plenty. And if intervals are new to you, start with what HIIT is and whether it suits beginners.

How can you start HIIT safely after 65?

Speak to your GP first, especially if you have not exercised for a while, have a heart or blood pressure condition, take regular medication or have had a fall. The NHS gives the same advice to anyone over 65 who has not been active for some time or has health concerns. Then follow a few simple rules:

• Build a base first. Spend a few weeks doing regular brisk walking or easy cycling before you add hard efforts.
• Warm up and cool down. Give yourself 5 to 10 minutes of easy movement before, and about 5 minutes after.
• Keep efforts short at first. Start with 20 to 30 seconds of work and much longer recoveries.
• Use the talk test. During an effort you should only manage a few words. In the recovery you should get back to chatting.
• Leave a day between interval sessions. Recovery is where your body adapts.
• Know when to stop. If you feel chest pain, dizziness or unusual breathlessness, stop and seek medical help.

Here is a gentle eight-week build-up you can take to your GP or a coach:

Keep up strength and balance work on 2 days a week throughout. If a week feels like too much, repeat it rather than moving on. There is no prize for rushing.

Should you still do strength training if you do HIIT?

Yes. The NHS recommends that adults aged 65 and over aim for 150 minutes of moderate activity a week, or 75 minutes of vigorous activity if they are already active, or a mix of both. On top of that, it recommends activities that improve strength, balance and flexibility on at least 2 days a week. Interval training counts towards your vigorous minutes, but it does not replace working your muscles against resistance.

Simple moves such as sit-to-stands from a chair, wall press-ups, step-ups and carrying shopping bags are a good place to begin. Our guide to strength training over 60 walks you through a safe first routine.

A balanced week might include two short interval sessions, two strength sessions, a little balance practice and plenty of everyday walking. That mix covers the NHS guidelines and gives you the possible benefits of intervals without relying on them alone.

How can Edge help you train well at any age?

Edge is a free fitness app with 20,000+ members. Edge Pro gives you a fully personalised plan across running, strength, HIIT and mobility, ready within 24 hours, so intervals, strength and easier days sit together in one plan rather than in separate apps. You can message a real coach anytime, which helps when you are starting later in life and want to talk through what feels right, including anything your GP has told you.

Edge Pro is from £19.99 a month, with a free 7-day trial (you need a card to start it). Edge syncs with Strava, Garmin, Apple Health and Coros, and you can log sessions manually too. Edge does not give medical advice, so your GP or physio always has the final say on what is right for you.

This article is general guidance, not medical advice. If you are new to exercise, returning from injury, or managing a health condition, speak to your GP before starting, and see a physio for any niggle that does not settle.