Article Series
Understanding Fitness and Health Metrics
What do your fitness and health measurements reveal about your cardiovascular health, disease risk and longevity?
A fitness watch can estimate your VO₂ max and resting heart rate. A blood pressure monitor can measure the pressure in your arteries. Bathroom scales can tell you your weight.
These numbers are easy to collect. What's more interesting is what they reveal about your health—and which ones are worth improving.
Research has established strong relationships between several of these measurements and long-term health outcomes. Understanding those relationships can help you identify where you're doing well, where there may be risks, and what changes could make a difference.
VO₂ max: One of the strongest indicators of longevity
VO₂ max measures your body's maximum capacity to use oxygen during intense exercise. It's an indicator of cardiorespiratory fitness: how effectively your heart, lungs, circulation and muscles work together.
Its importance extends well beyond sporting performance.
A major 2024 review published in the British Journal of Sports Medicine brought together research representing more than 20 million observations. It found that people with high aerobic fitness had approximately half the risk of dying during the studies' follow-up periods compared with people with low fitness.
Across the studies, each additional MET of aerobic fitness—a standard unit used to measure exercise capacity—was associated with an 11–17% lower risk of death from any cause.
These findings don't guarantee that improving your VO₂ max will extend your life. But they provide strong evidence that aerobic fitness matters for long-term health.
What does this mean for you?
If your aerobic fitness is low, improving it is a worthwhile objective, even if you have no interest in athletic performance.
Walking briskly, cycling, swimming and other regular aerobic activities can help improve it.
Wearable devices can estimate VO₂ max, although their accuracy varies. They're useful for following changes over time, but the estimates aren't equivalent to laboratory measurements.
Explore: What Is VO₂ Max and Why It Matters
Resting heart rate: What your heart reveals about your fitness
Your resting heart rate measures how many times your heart beats each minute when you're resting.
Here's what makes it interesting.
Regular aerobic training can make your heart more efficient. As it becomes capable of pumping more blood with each beat, it may need fewer beats to supply your body while you're at rest.
That's one reason endurance athletes often have remarkably low resting heart rates.
For most adults, between 60 and 100 beats per minute is considered a typical resting range. Well-trained athletes may have resting rates substantially below 60.
But resting heart rate isn't simply a fitness score. Medications, stress, illness and other factors can influence it.
What does this mean for you?
As your aerobic fitness improves, your resting heart rate will often decrease. For example, if regular exercise brings your resting heart rate down from 75 to 65 beats per minute, that may be a sign that your heart has become stronger and more efficient.
That's what makes resting heart rate such a useful fitness measurement. It's easy to track, and changes over several months can help show how your cardiovascular system is responding to training.
For most people, a lower resting heart rate is associated with better aerobic fitness. Other factors can affect it, of course, and an unusually slow heart rate accompanied by dizziness or fainting needs medical assessment. But the main thing worth watching is how your resting heart rate changes as your fitness develops.
Explore: How to Measure Your Resting Heart Rate
Blood pressure: A major indicator of cardiovascular risk
Blood pressure deserves particular attention because high blood pressure is one of the leading preventable causes of heart disease and stroke.
When blood pressure remains elevated, the increased force against artery walls can damage blood vessels over time. This increases the risk of heart attack, stroke, heart failure and kidney disease.
And here's something important: you can have excellent aerobic fitness and still have high blood pressure.
Being able to run long distances or cycle up demanding hills doesn't necessarily mean your blood pressure is healthy. Aerobic fitness and blood pressure tell us different things about the cardiovascular system.
What do the numbers mean?
Blood pressure is recorded as two figures, such as 120/80 mmHg.
The first is systolic pressure, measured when the heart contracts. The second is diastolic pressure, measured when the heart relaxes between beats.
Australian guidance uses the following general categories for adults:
| Blood pressure | Interpretation |
|---|---|
| Below 120/80 | Optimal |
| 120–129 and/or 80–84 | Normal |
| 130–139 and/or 85–89 | High-normal |
| 140/90 or higher | High blood pressure |
The higher category applies when either number reaches that range. The figures are general guides; individual treatment targets may differ.
Source: Healthdirect Australia — Healthy blood pressure.
A single elevated reading doesn't necessarily mean you have high blood pressure. Doctors usually assess repeated measurements to establish whether the problem is persistent.
What does this mean for you?
You can have high blood pressure for years without knowing it. It often causes no noticeable symptoms, even while increasing your risk of heart disease and stroke. That's why regular blood pressure checks are important. See the Australian Heart Foundation's guidance.
If your blood pressure is consistently elevated, there are effective ways to reduce it. Regular exercise, reducing excess salt, improving your diet, limiting alcohol and managing body weight where appropriate can all help.
Some people also need medication. Treating high blood pressure can substantially reduce the risk of serious cardiovascular problems.
Explore: How to Measure Your Blood Pressure
Weight: What matters beyond the scales?
Body weight is often used as an indicator of health, but weight alone cannot tell you how aerobically fit someone is.
Research comparing body weight, fitness and longevity has produced some striking findings.
A 2024 systematic review published in the British Journal of Sports Medicine examined 20 studies covering nearly 400,000 observations.
The researchers compared mortality rates among people of different weights and fitness levels.
They found that people with poor aerobic fitness had approximately twice the risk of dying during the studies' follow-up periods compared with aerobically fit people of normal weight. This was true whether the unfit participants were classified as normal weight, overweight or obese.
Among people who were aerobically fit, the researchers found no statistically significant difference in mortality risk between the weight categories.
The finding is striking: aerobic fitness was strongly associated with longevity, independently of body weight.
This doesn't mean excess body fat is harmless or that weight never matters. It means the number on the scales can overlook an important part of someone's health.
What does this mean for you?
Improving aerobic fitness is a valuable health objective regardless of your current weight.
Whether weight loss itself should be a priority depends on your circumstances and health risks. It shouldn't be assumed that everyone needs a particular number on the scales.
Our article Weight Goals, Health, and When to Skip the Numbers examines the limitations of weight-based targets and when they may or may not be helpful.
What do these measurements tell us together?
Good aerobic fitness doesn't rule out high blood pressure, and normal blood pressure doesn't guarantee good aerobic fitness.
Someone who runs regularly might have excellent aerobic fitness but high blood pressure. Their exercise capacity is a health advantage, but their blood pressure still increases their risk of heart disease and stroke.
Someone else might have perfectly normal blood pressure but poor aerobic fitness. They don't have the same blood-pressure concern, but improving their aerobic fitness could offer substantial long-term health benefits.
Each measurement reveals something different:
- VO₂ max indicates aerobic capacity, which is strongly associated with longevity.
- Resting heart rate can reflect cardiovascular conditioning and how your heart responds to training.
- Blood pressure reveals an important risk factor for heart disease and stroke that can often be treated.
- Body weight, considered alongside fitness and other health information, can help identify risks that may warrant attention.
The practical message is straightforward: improving aerobic fitness and maintaining healthy blood pressure are both important, and neither replaces the other.
Body weight and resting heart rate can provide additional information, helping you build a more complete understanding of your health.
Explore the four articles
Read further about each measurement and what it can—and cannot—tell you.
What Is VO₂ Max and Why It Matters
What VO₂ max measures, how it relates to aerobic fitness and why it matters for long-term health.
Read article →Resting Heart Rate
How resting heart rate relates to cardiovascular conditioning and responds to regular exercise.
Read article →How to Measure Your Blood Pressure
What blood pressure readings mean and how to obtain reliable measurements.
Read article →Weight Goals, Health, and When to Skip the Numbers
When weight goals are helpful, when they are not, and why health involves more than a number on the scales.
Read article →Use optimal to follow your progress
optimal helps you record activities, set fitness goals and explore changes in your health and fitness data.
You can use your activity history alongside measurements such as resting heart rate and estimated VO₂ max to see how your fitness develops.
For medical measurements such as blood pressure, recording results can also provide useful information to discuss with your GP.
Research and further reading
- Cardiorespiratory fitness and health outcomes in adults: an overview of systematic reviews. British Journal of Sports Medicine, 2024.
- Cardiorespiratory fitness, body mass index and mortality: a systematic review and meta-analysis. British Journal of Sports Medicine, published online 2024.
- What is a healthy blood pressure? Healthdirect Australia.
- High blood pressure and how to lower it. Healthdirect Australia.
- Blood pressure and your heart. Australian Heart Foundation.