If you spend a lot of time exploring fitness content online, you might have come across the concept of heart rate zones. Heart rate zone training has become more popular in recent years partly because of the boom in wearable technology which, among other functions, allows people to easily track their heart rates.

Heart rate zones reflect different levels of intensity during aerobic exercise. They’re most often based on a percentage of your maximum heart rate, which is the highest number of beats your heart can achieve per minute.

But what are the different heart rate zones, and how can you use these zones to optimise your workout?

The three-zone model

While there are several models used to describe heart rate zones, the most common model in the scientific literature is the three-zone model, where the zones may be categorised as follows:

• zone 1: 55%–82% of maximum heart rate
• zone 2: 82%–87% of maximum heart rate
• zone 3: 87%–97% of maximum heart rate.

If you’re not sure what your maximum heart rate is, it can be calculated using this equation: 208 – (0.7 × age in years). For example, I’m 32 years old. 208 – (0.7 x 32) = 185.6, so my predicted maximum heart rate is around 186 beats per minute.

There are also other models used to describe heart rate zones, such as the five-zone model (as its name implies, this one has five distinct zones). These models largely describe the same thing and can mostly be used interchangeably.

What do the different zones involve?

The three zones are based around a person’s lactate threshold, which describes the point at which exercise intensity moves from being predominantly aerobic, to predominantly anaerobic.

Aerobic exercise uses oxygen to help our muscles keep going, ensuring we can continue for a long time without fatiguing. Anaerobic exercise, however, uses stored energy to fuel exercise. Anaerobic exercise also accrues metabolic byproducts (such as lactate) that increase fatigue, meaning we can only produce energy anaerobically for a short time.

On average your lactate threshold tends to sit around 85% of your maximum heart rate, although this varies from person to person, and can be higher in athletes.

In the three-zone model, each zone loosely describes one of three types of training.

Zone 1 represents high-volume, low-intensity exercise, usually performed for long periods and at an easy pace, well below lactate threshold. Examples include jogging or cycling at a gentle pace.

Zone 2 is threshold training, also known as tempo training, a moderate intensity training method performed for moderate durations, at (or around) lactate threshold. This could be running, rowing or cycling at a speed where it’s difficult to speak full sentences.

Zone 3 mostly describes methods of high-intensity interval training, which are performed for shorter durations and at intensities above lactate threshold. For example, any circuit style workout that has you exercising hard for 30 seconds then resting for 30 seconds would be zone 3.

Striking a balance

To maximise endurance performance, you need to strike a balance between doing enough training to elicit positive changes, while avoiding over-training, injury and burnout.

While zone 3 is thought to produce the largest improvements in maximal oxygen uptake – one of the best predictors of endurance performance and overall health – it’s also the most tiring. This means you can only perform so much of it before it becomes too much.

Training in different heart rate zones improves slightly different physiological qualities, and so by spending time in each zone, you ensure a variety of benefits for performance and health.

So how much time should you spend in each zone?

Most elite endurance athletes, including runners, rowers, and even cross-country skiers, tend to spend most of their training (around 80%) in zone 1, with the rest split between zones 2 and 3.

Because elite endurance athletes train a lot, most of it needs to be in zone 1, otherwise they risk injury and burnout. For example, some runners accumulate more than 250 kilometres per week, which would be impossible to recover from if it was all performed in zone 2 or 3.

Of course, most people are not professional athletes. The World Health Organization recommends adults aim for 150–300 minutes of moderate intensity exercise per week, or 75–150 minutes of vigorous exercise per week.

If you look at this in the context of heart rate zones, you could consider zone 1 training as moderate intensity, and zones 2 and 3 as vigorous. Then, you can use heart rate zones to make sure you’re exercising to meet these guidelines.

What if I don’t have a heart rate monitor?

If you don’t have access to a heart rate tracker, that doesn’t mean you can’t use heart rate zones to guide your training.

The three heart rate zones discussed in this article can also be prescribed based on feel using a simple 10-point scale, where 0 indicates no effort, and 10 indicates the maximum amount of effort you can produce.

With this system, zone 1 aligns with a 4 or less out of 10, zone 2 with 4.5 to 6.5 out of 10, and zone 3 as a 7 or higher out of 10.

Heart rate zones are not a perfect measure of exercise intensity, but can be a useful tool. And if you don’t want to worry about heart rate zones at all, that’s also fine. The most important thing is to simply get moving.

Hunter Bennett, Lecturer in Exercise Science, University of South Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

From today, February 3, pregnant women in Australia will be eligible for a free RSV vaccine under the National Immunisation Program.

This vaccine is designed to protect young infants from severe RSV (respiratory syncytial virus). It does so by generating the production of antibodies against RSV in the mother, which then travel across the placenta to the baby.

While the RSV vaccine is a new addition to the National Immunisation Program, it’s one of three vaccines provided free for pregnant women under the program, alongside ones for influenza and whooping cough. Each offers important protection for newborn babies.

The RSV vaccine

RSV is the most common cause of lower respiratory infections (bronchiolitis and pneumonia) in infants. It’s estimated that of every 100 infants born in Australia each year, at least two will be hospitalised with RSV by six months of age.

RSV infection is most common roughly between March and August in the southern hemisphere, but infection can occur year-round, especially in tropical areas.

The vaccine works by conferring passive immunity (from the mother) as opposed to active immunity (the baby’s own immune response). By the time the baby is born, their antibodies are sufficient to protect them during the first months of life when they are most vulnerable to severe RSV disease.

The RSV vaccine registered for use in pregnant women in Australia, Abrysvo, has been used since 2023 in the Americas and Europe. Real-world experience there shows it’s working well.

For example, over the 2024 RSV season in Argentina, it was found to prevent 72.7% of lower respiratory tract infections caused by RSV and requiring hospitalisation in infants aged 0–3 months, and 68% among those aged 0–6 months. This research noted three deaths from RSV, all in infants whose mothers did not receive the RSV vaccine during pregnancy.

This was similar to protection seen in a large multinational clinical trial that compared babies born to mothers who received this RSV vaccine with babies born to mothers who received a placebo. This study found the vaccine prevented 82.4% of severe cases of RSV in infants aged under three months, and 70% under six months, and that the vaccine was safe.

In addition to the maternal vaccine, nirsevimab, a long-acting monoclonal antibody, provides effective protection against severe RSV disease. It’s delivered to the baby by an intramuscular injection, usually in the thigh.

Nirsevimab is recommended for babies born to women who did not receive an RSV vaccine during pregnancy, or who are born within two weeks of their mother having received the shot (most likely if they’re born prematurely). It may also be recommended for babies who are at higher risk of RSV due to a medical condition, even if their mother was vaccinated.

Nirsevimab is not funded under the National Immunisation Program, but is covered under various state and territory-based programs for infants of mothers who fall into the above categories.

But now we have a safe and effective RSV vaccine for pregnancy, all pregnant women should be encouraged to receive it as the first line of prevention. This will maximise the number of babies protected during their first months of life.

Flu and whooping cough

It’s also important pregnant women continue to receive flu and whooping cough vaccines in 2025. Like the RSV vaccine, these protect infants by passing antibodies from mother to baby.

There has been a large whooping cough outbreak in Australia in recent months, including a death of a two-month-old infant in Queensland in November 2024.

The whooping cough vaccine, given in combination with diphtheria and tetanus, prevents more than 90% of whooping cough cases in babies too young to receive their first whooping cough vaccine dose.

Similarly, influenza can be deadly in young babies, and maternal flu vaccination substantially reduces hospital visits associated with influenza for babies under six months. Flu can also be serious for pregnant women, so the vaccine offers important protection for the mother as well.

COVID vaccines are safe in pregnancy, but unless a woman is otherwise eligible, they’re not routinely recommended. You can discuss this with your health-care provider.

When and where can you get vaccinated?

Pregnant women can receive these vaccines during antenatal visits through their GP or in a specialised antenatal clinic.

The flu vaccine is recommended at any time during pregnancy, the whooping cough vaccine from 20 weeks (ideally before 32 weeks), and the RSV vaccine from 28 weeks (before 36 weeks).

It’s safe to receive multiple vaccinations at the same clinic visit.

We know vaccination rates have declined in a variety of groups since the pandemic, and there’s evidence emerging that suggests this trend has occurred in pregnant women too.

A recent preprint (a study yet to be peer-reviewed) found a decrease of nearly ten percentage points in flu vaccine coverage among pregnant women in New South Wales, from 58.8% in 2020 to 49.1% in 2022. The research showed a smaller drop of 1.4 percentage points for whooping cough, from 79% in 2020 to 77.6% in 2022.

It’s important to work to improve vaccination rates during pregnancy to give babies the best protection in their first months of life.

We know pregnant women would like to receive information about new and routine maternal vaccines early in pregnancy. In particular, many pregnant women want to understand how vaccines are tested for safety, and their effectiveness, which was evident during COVID.

GPs and midwives are trusted sources of information on vaccines in pregnancy. There’s also information available online on Sharing Knowledge About Immunisation, a collaboration led by the National Centre for Immunisation Research and Surveillance.

Archana Koirala, Paediatrician and Infectious Diseases Specialist, University of Sydney; Bianca Middleton, Senior Research Fellow, Menzies School of Health Research; Margie Danchin, Professor of Paediatrics and vaccinologist, Royal Childrens Hospital, University of Melbourne and Murdoch Childrens Research Institute (MCRI); Associate Dean International, University of Melbourne, Murdoch Children’s Research Institute; Peter McIntyre, Professor in Women’s and Children’s Health, University of Otago, and Rebecca Doyle, Adjunct Research Fellow, School of Nursing, Midwifery and Social Work, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.