I’m an Exercise Physiologist. These Are the Health Metrics I Actually Track
By Fredrick Peters, Ph.D., ACSM-EP
We have access to more health data than ever before.
Your smartwatch can estimate your stress, sleep, heart rate variability, calories burned, recovery, “body battery,” and even your VO₂max.
Your bathroom scale can estimate body fat, muscle mass, water weight, visceral fat, and metabolic age.
But more data doesn’t necessarily mean better health.
As an exercise physiologist, I’m much more interested in a relatively small number of measurements that tell me something meaningful about cardiovascular health, metabolic health, physical function, and how well we are likely to age.
Some require laboratory testing. Others can be measured at home. And some don't need to be tracked every day, or even every year.
Here are the health metrics I believe are actually worth paying attention to.
1. Cardiorespiratory Fitness
If I had to choose one fitness-related measurement that deserves more attention, it would be cardiorespiratory fitness.
Cardiorespiratory fitness reflects how effectively your cardiovascular and respiratory systems can supply oxygen to your working muscles and how effectively those muscles can use it. It is commonly expressed as VO₂max or VO₂peak.
Why do I care so much about it?
Because cardiorespiratory fitness is consistently associated with health outcomes, including cardiovascular disease and all-cause mortality. Across large populations, people with greater fitness generally have substantially better long-term outcomes than those with very low fitness.
And unlike your age or genetics, fitness is modifiable.
You improve it through exercise.
Moderate-intensity aerobic exercise builds your aerobic foundation, while appropriately prescribed higher-intensity exercise can provide a powerful stimulus for improving VO₂max.
A laboratory exercise test provides the most accurate assessment. Wearables can provide useful estimates, but I treat those numbers primarily as trends rather than laboratory-grade measurements.
What matters most: Don't become obsessed with whether your watch says your VO₂max is 42 or 44. Pay attention to whether your cardiorespiratory fitness is improving, declining, or remaining strong as you age.
2. Strength and Muscle Function
We tend to associate strength training with appearance.
I think that dramatically undersells its importance.
As we age, maintaining skeletal muscle and (perhaps even more importantly) our ability to produce force becomes increasingly important for physical function and independence.
This is where the distinction between sarcopenia and dynapenia becomes important. Sarcopenia refers broadly to age-related deterioration involving skeletal muscle, while dynapenia specifically describes the age-related loss of muscular strength.
You don't need to become a competitive powerlifter to benefit from resistance training.
I want to see people maintain the ability to push, pull, squat, carry, get off the floor, climb stairs, and perform the activities that make an independent life possible.
That is why I view resistance training as an investment in longevity, not simply aesthetics.
What matters most: Track performance over time. Are you maintaining or improving your strength? Can you perform the same tasks at 50, 60, and 70 that you could years earlier?
3. Blood Pressure
Blood pressure isn't exciting.
It is, however, extraordinarily important.
Hypertension is a major modifiable risk factor for cardiovascular disease, stroke, kidney disease, and other adverse health outcomes.
A normal blood pressure is generally considered below 120/80 mm Hg, while persistent measurements above the normal range warrant attention and, depending on the values and overall cardiovascular risk, discussion with a healthcare professional.
One advantage of blood pressure is that it is inexpensive and relatively easy to measure.
If you're monitoring it yourself, use a validated upper-arm cuff, follow proper measurement procedures, and look at your average readings rather than reacting to one isolated measurement.
What matters most: Know your blood pressure. This is one of those simple numbers that can provide genuinely important information.
4. Blood Lipids and Cardiovascular Risk
Most people have heard of LDL cholesterol.
It remains important, but cardiovascular risk assessment has become considerably more sophisticated.
A standard lipid panel provides LDL-C, HDL-C, triglycerides, and total cholesterol. Non-HDL cholesterol can also be useful because it captures cholesterol contained within atherogenic particles beyond LDL alone.
Another marker receiving increasing attention is apolipoprotein B, or ApoB. Because each major atherogenic particle generally contains one ApoB molecule, ApoB can provide information about the number of circulating atherogenic lipoprotein particles.
Then there is lipoprotein(a), or Lp(a).
Lp(a) is largely genetically determined and is an independent cardiovascular risk factor. Importantly, current cardiovascular guidelines recommend that adults have Lp(a) measured at least once during their lifetime.
Unlike something such as daily steps, this isn't a metric you need to continuously track. For most people, the important first step is simply knowing whether it is elevated.
What matters most: Don't evaluate cardiovascular health from total cholesterol alone. Understand your overall risk profile and discuss appropriate testing with your healthcare professional.
5. Body Composition and Waist Circumference
I care about body weight.
I just don't think body weight tells the whole story.
Two people can weigh exactly the same amount and have very different amounts of skeletal muscle, adipose tissue, and abdominal fat.
That is why I prefer to think in terms of body composition rather than simply scale weight.
Waist circumference can also provide useful information because abdominal adiposity is associated with cardiometabolic risk.
There is an important caveat here: consumer smart scales are not particularly precise instruments for measuring body-fat percentage. Hydration status and other variables can influence their estimates.
If you use one, look at long-term trends rather than celebrating because your body fat supposedly fell 0.4% overnight.
It didn't.
What matters most: Consider weight, waist circumference, body composition, and physical performance together rather than allowing a single number on the scale to define progress.
6. Daily Movement
You've probably heard that everyone needs 10,000 steps per day.
There is nothing magical about 10,000.
Recent evidence reinforces that substantial health benefits occur below that threshold.
A large 2025 meta-analysis published in The Lancet Public Health found that approximately 7,000 steps per day was associated with substantial health benefits compared with very low daily step counts.
That doesn't mean 7,000 is a magic number either.
If you're averaging 2,500 steps per day, getting to 5,000 is meaningful progress. If you're already averaging 8,000 or 10,000, there's no reason to deliberately walk less.
The broader principle is more important:
Move frequently and avoid spending most of your waking hours sedentary.
And remember that steps and structured exercise aren't interchangeable. Walking is excellent physical activity, but it doesn't eliminate the value of resistance training and exercise performed at intensities sufficient to challenge cardiorespiratory fitness.
What matters most: Use step counts as a practical measure of habitual movement, not as a daily pass/fail test.
7. Sleep
Sleep belongs in the conversation about health and performance.
Most adults should generally aim for approximately 7–9 hours of sleep per night, but duration isn't the only consideration.
Regularity, quality, timing, sleep efficiency, and the presence of sleep disorders all matter.
This is another area where wearables can become counterproductive.
Your watch may provide useful information about sleep duration and trends, but I wouldn't allow a proprietary sleep score to determine how you think you're supposed to feel that morning.
If you slept reasonably well, feel rested, and are functioning normally, a watch telling you that you received a sleep score of 68 doesn't suddenly make it a bad night.
What matters most: Prioritize sufficient, regular, restorative sleep and address persistent sleep problems rather than chasing a perfect wearable score.
The Health Metrics I Don't Obsess Over
Technology has made health monitoring easier. It has also made it easier to become distracted by numbers that aren't particularly actionable.
I don't put much weight on:
Daily fluctuations in body weight
Exact calorie-burn estimates from wearables
Small day-to-day changes in HRV
Proprietary readiness or “body battery” scores
One unusually good or bad night of sleep
Tiny changes in smart-scale body-fat estimates
Hitting exactly 10,000 steps every single day
That doesn't mean these measurements are completely useless.
The distinction is between data that provides context and data that should drive decisions.
Measure What Matters
The goal of tracking your health shouldn't be to generate as much data as possible.
It should be to identify meaningful variables, understand what they tell you, and use that information to make better decisions.
For me, that means paying particular attention to cardiorespiratory fitness, strength and physical function, blood pressure, cardiovascular risk markers, body composition, habitual movement, and sleep.
You don't need perfect numbers.
You want favorable trends, and, ideally, you want to preserve those favorable trends for decades.
Because ultimately, the objective isn't to produce the best-looking health dashboard.
It's to remain healthy, capable, and physically independent for as much of your life as possible.
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Fredrick Peters, Ph.D., ACSM-EP, is an exercise physiologist, university professor, health and fitness expert, and media contributor specializing in exercise science, health, performance, and longevity.
This article is for educational purposes and is not intended to diagnose, treat, or replace individualized medical advice. Discuss laboratory testing, cardiovascular risk, and changes to your exercise or medical management with an appropriate healthcare professional.
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