4 health metrics to start tracking today

The first rule of the EnduroLiving system is that no single metric tells a full story. The power of data comes from looking at patterns across multiple signals. How does your sleep shape your heart rate? Can your recovery keep up with your training load? All of these points paint an honest picture of your body, what it needs and where it’s going.

The good news is that you don't need many signals to start seeing that picture. Here are four metrics you can begin tracking on your devices today.

1. Heart rate variability (HRV)

A heart beating at 60 beats per minute (bpm) isn't actually beating exactly once per second like a metronome. The gaps between heart beats fluctuate. HRV is the tiny, natural variation in the time between each of your heartbeats, measured in milliseconds. 

Those fluctuations are governed by your autonomic nervous system, which means HRV offers a rare window into the tug-of-war between your sympathetic ("fight-or-flight") and parasympathetic ("rest-and-digest") systems. When your body is relaxed, recovered, and adapting well, the parasympathetic side has more say, and HRV tends to be higher. When you're under strain and stressed, variability drops as the sympathetic system prevails.

A good average HRV ranges widely from 20ms to 200ms but, as a rule of thumb, a higher HRV is better. This suggests your body handles stress well and is ready to absorb workload. A high HRV score is typically associated with good fitness and health, according to Harvard Medical School. But, as we said earlier, the occasional high HRV reading doesn’t tell us much. The real value of tracking HRV emerges over weeks and months, when it starts reflecting something both humbling and empowering: your nervous system responds to the lifestyle you give it. There will be stressful stretches and troughs — that's life. But invest consistently in the right habits, and the trend bends upward, along with your resilience.

2. Resting heart rate (RHR)

Simply put, this is your heart rate when your body is fully at rest, and it is typically measured first thing in the morning. The lower the number, the less work your heart is doing to keep your engine running at idle.

Research by Harvard Medical School reveals that RHR can offer a simple view of cardiovascular efficiency. According to the Mayo Clinic, a healthy average RHR is 60-100bpm. Fitter individuals tend to sit lower in the 40–60 bpm range, and elite endurance athletes can reach frankly ridiculous numbers. Five-time Tour de France winner Miguel Indurain, for example, was famously measured at 28bpm, though by his own account his everyday resting rate was a "normal" 30-32.

Don’t worry, you don't need to chase Miguel. RHR and heart rate are deeply individual, so a number without context won't tell you much. What matters is your baseline and your normal. If you wake up one morning and notice that your RHR is 5–10bpm above your usual, that could be a sign that your body is under significant stress. Maybe you're under-recovered, fighting something off, or simply carrying too much training load. 

Seen early, these readings can empower you to make small course corrections. Ignored, they could very well become the injury, illness, or burnout you "didn't see coming."

3. Sleep

Sleep is arguably the most important metric on this list, because it touches almost everything else. The average adult needs between seven and nine hours of sleep per night to function healthily, according to the National Sleep Foundation. Any less can have detrimental effects on many fronts.

There is plenty of scientific evidence showing the hidden cost of poor sleep. The Sleep Foundation revealed that accumulating a sleep debt – the difference between the sleep your body needs and how much it actually gets – can increase the risk of diabetes, hypertension, heart disease, and stroke. Sleep deprivation is also linked to reduced immune function, metabolic dysregulation and weight gain, and a greater risk of falls and accidents. Prolonged sleep deprivation also affects memory and cognitive functions. Columbia University’s Department of Psychiatry has also shown the effects of sleep deprivation on mental health.

The cost of bad sleep is enormous, and it compounds quietly. You can borrow against it for a while to get through the day, but you can't avoid paying forever.

The goal isn't perfection. Chasing a flawless eight hours every single night is its own kind of stress, and it misses the point. The goal is to improve the average. Track it honestly and you'll quickly see which behaviours move that needle. Then the choice, as always, is yours.

4. Training load

Training load is the the total amount of physical stress and strain that your training places on your body. It looks at how long and how often you train (volume) and how hard you train (intensity).

Keeping an eye on training load is the difference between working hard and working smart. It's easy to fall into the trap of believing that the harder a session feels, the more productive it is. But that's simply not true.

Think of it like heat in cooking. A red-hot pan will sear a steak beautifully — but it would ruin a stew. Sometimes what the dish needs is a long, slow simmer that lets the flavours develop. Sometimes it needs no heat at all. Your heart rate zones work the same way. Intensity is a tool to be used with purpose and precision. How much intensity you apply and how long you apply it depends entirely on what you're trying to build.

Once you start tracking training load, a pattern reveals itself. The biggest gains come from consistency and aerobic volume, not from forcing intensity into every session. It’s this simple truth that founded well-established training philosophies like the polarised 80/20 rule. Stack enough sensible weeks on top of each other and you build a genuine engine. Redline every workout and you're not building anything; you're just collecting fatigue.

The data won't do the work

Data does not create change on its own. That’s still your job. But tracking these four key metrics can show you an honest picture of what's working, what's quietly costing you, and where you might need to be more honest with yourself.

So, here's our challenge. Pick one of these four metrics and start tracking it today. Don't overhaul your life. Just watch. Pay attention to how the number responds when you make small tweaks to your habits. That connection between action and outcome is where everything starts. Once you can see it, you can steer it.