The Basics of HRV and RHR (And How Tracking Them Can Help)

You wake up feeling “fine”… but is your body really ready for another hard session?

Most people rely on how they feel to decide if they’re recovered.

But feelings lie.

That’s where heart rate variability (HRV) and resting heart rate (RHR) come in.

Two simple numbers that can offer powerful insight into your recovery, training readiness, and even early illness.

But here’s the catch: not all readings are created equal.

HRV vs. RHR: what they measure

Resting Heart Rate (RHR) is the number of times your heart beats per minute while you’re at complete rest, ideally when you first wake up.

A lower RHR generally indicates better cardiovascular fitness and recovery.

When your RHR is higher than normal, it’s often a sign of stress, poor sleep, dehydration, or that you're not fully recovered.

Heart Rate Variability (HRV) measures the variation in time between each heartbeat.

A higher HRV typically reflects a more responsive, adaptable nervous system and better recovery.

A lower HRV means your body may be under stress or not bouncing back well from training.

In simple terms:

• Normal+ RHR + Normal+ HRV = Recovered, ready to train.
• High RHR + Low HRV = Likely stressed or under-recovered.

This becomes even more important if you’re chasing multiple goals, the kind I broke down in Can You Build Muscle, Get Stronger, and Improve Endurance at the Same Time?

Morning vs. overnight readings: what’s better?

This is where a lot of people get tripped up.

Morning HRV and RHR readings (like those taken with HRV4Training or a chest strap upon waking) are consistent and reliable if you do them the same way every day: same time, same position, same breathing.

They reflect your recovery state right before you start your day, which makes them more useful for training readiness decisions.

If your morning HRV is lower than usual, it’s a strong signal that your body might not be ready to push hard.

The downside?

They’re also easy to mess up.

Forget to measure?

Bad posture?

Drank coffee first?

All of these can skew your numbers.

Overnight readings (like those from WHOOP, Oura, or 8 Sleep) track your data passively while you sleep.

They’re less prone to user error and provide a full-night view of recovery, sleep quality, and stress.

That said, overnight HRV is typically lower than a morning HRV taken under ideal conditions, and that’s completely normal.

So which is better?

• For daily training decisions → Morning readings are better.
• For general recovery trends → Overnight data is more hands-off and (usually) more consistent.

The key is consistency.

Personally, I use both.

HRV4Training is used every morning for same-day training readiness.

On a day-to-day basis, I essentially ignore overnight readings.

BUT, overnight readings are useful for viewing trends, and overnight readings will typically show a clear downward trend before morning readings.

In that sense, overnight readings are sort of an early warning system for overtraining.

If you see overnight HRV trending down over weeks or months but morning readings are still, for the most part, good, you should strongly consider reducing training volume and/or prioritizing recovery/sleep/nutrition.

Once morning readings start consistently trending down, you are in quite a hole.

How to actually use HRV and RHR

Here’s a simple way to use these numbers to guide your training:

1. Track your baseline. Don’t make decisions based on one weird number. Look at trends across 7–10 days.
2. Look for changes. If your RHR spikes by 8–10 bpm above your baseline and HRV drops significantly, you’re probably not ready for a hard session, even if you feel fine. Or, you are 12-48 hours away from getting sick.
3. Adjust when needed. Low HRV + high RHR? Swap that threshold run for a zone 1 ride or extra sleep.
   Stable HRV + low RHR? Full steam ahead.
4. Watch for false alarms. Travel, alcohol, poor sleep, dehydration, or even high-carb intake can all skew your numbers. Context matters.

The big picture

HRV and RHR don’t replace good coaching or listening to your body, but they do give you an objective lens.

Over time, you’ll start noticing patterns that help you train smarter, avoid burnout, and even catch illness before symptoms appear.

Takeaway

I recommend using both, an overnight reading and a morning reading.

Track it daily.

Use morning readings to guide your training that day.
Use overnight readings to guide long-term training.

It’s one of the simplest and most powerful recovery tools you can use.

Call to action

If you’re not already tracking HRV and RHR, start this week.

Use your smartwatch, an app like HRV4Training, or a wearable like WHOOP or Oura.

Capacity Training

I built Capacity Training to plan your running and your lifting together, with an optional readiness check before a workout that asks about your sleep, stress, energy, soreness and motivation. On a rough day it can suggest a lighter session or a rest day, and you decide.

Run faster. Get stronger. capacitytraining.app

Mike