What’s the Difference Between Heart Rate and Power Training? – Should I Buy A Power Meter?

When you start training with BLOC Coaching, we’ll often talk about zones, FTP, and thresholds—but how do you actually measure intensity?

There are two main tools endurance athletes use:

  • Heart rate (HR)
  • Power

They each have their place, and when you understand how they work—and how they work together—your training becomes smarter, more specific, and way more effective. The important thing is that you’re able to measure your training effort, so we’re training in the right zones at the right time.

💓 Heart Rate Training: How It Works

Heart rate training uses your beats per minute (BPM) to track how hard your body is working. It reflects your internal effort—how your cardiovascular system is responding to training.

✅ Pros of heart rate training:

  • Inexpensive (most watches or chest straps will do the job)
  • Reflects physiological stress on the body
  • Great for measuring recovery and aerobic efficiency
  • Good for long, steady efforts like Zone 2 runs or rides

🚫 Limitations:

  • Lag time (it can take 30–90 seconds for HR to respond to intensity)
  • Influenced by external factors (heat, caffeine, dehydration, fatigue)
  • Not as precise for short intervals or power-based sessions
  • Wrist based heart rate monitors are often the least accurate (we advise against them)

 

⚡ Power Training: What It Measures

Power training (on the bike) measures watts—the actual work you're producing. This makes it an external measure of effort: how much force you're generating, right now.

✅ Pros of power training:

  • Instant feedback—no lag
  • Not influenced by heat, sleep, or emotions
  • Allows for super-precise interval and race pacing
  • Ideal for FTP testing, hill reps, and time trial efforts

🚫 Limitations:

  • More expensive (you need a power meter or smart trainer)
  • Doesn’t tell you how your body is coping internally
  • Can lead to “chasing numbers” if not balanced with HR or feel

 

So… Which One Should You Use?

Honestly? Both. They each give you a different piece of the puzzle and by combining heart rate data with power data we can more accurately understand what has happened during your training session.

Here’s how we typically recommend using them:

Session Type

Use Heart Rate?

Use Power?

Easy Zone 2 endurance

✅ Primary tool

Optional

High-intensity intervals

✅ Secondary

✅ Primary

Long steady tempo efforts

✅ Important

✅ Important

Tired or recovery weeks

✅ Vital to track fatigue

Less useful

FTP tests

✅ To monitor response

✅ Essential

Power tells you what you’re doing.
Heart rate tells you how your body is reacting.
Together, they paint the full picture.

 

So, Should You Invest in a Power Meter?

If you’re training seriously on the bike—and especially if you’re training for triathlon or time trials—then yes, we usually recommend getting one.

A power meter is worth it if:

  • You’re training consistently 3–5x a week on the bike
  • You’re doing structured intervals or FTP work
  • You want accurate pacing for races and tests
  • You’re ready to take your performance to the next level

What kind to get?

  • Pedal-based power meters (like Favero Assioma or Garmin Rally) are popular for easy install and transferability, you can have one power meter and share it easily across your bikes.
  • Crank/spider-based options (like Quarq, 4iiii, or Shimano) offer great reliability
  • Smart trainers (like Wahoo Kickr or Tacx Neo) can also measure power for indoor sessions, but obviously you can’t take them outside to the roads

Expect to pay around £300–£600 for entry-level, or more for dual-sided models. We’d say that you don’t really need a dual sided power meter, single sided gives ample data.

You don’t need a power meter to train well. Many of our BLOC athletes get great results using heart rate and perceived effort alone.

But if you want to train with precision, track gains over time, and dial in your performance—then power is one of the best tools you can invest in. More than upgrading your kit.

As always, if you're unsure about anything, reach out to your coach—we're here to help you every step of the way.

If you are not a BLOC coached athlete but would like to be, book in for a FREE call to chat more about how we can work together.

Alternatively, join our Community Membership plan and race for the team while taking full advantage of the supportive community and friendships (and you get to wear our awesome team kit too!)