Heart Rate Zones for Runners and Lifters: A Practical Guide

2026-05-16 · ~8 min read · By the FitLife coaching team

Heart rate training has gone mainstream — every fitness watch now displays "zones" during workouts. What most users don't know is what those zones mean, why they matter, and how a runner's relationship to them differs from a lifter's.

The 5-zone system

Modern heart rate training divides effort into five zones. The percentages are of Heart Rate Reserve (HRR), not max HR — HRR accounts for resting fitness:

• HRR = Max HR − Resting HR
• Target HR for zone X = Resting HR + (HRR × zone%)

This is the Karvonen formula. It's significantly more accurate than the old "% of max HR" method, especially for fit individuals with low resting heart rates.

The zones

Worked example

35-year-old, max HR ~185, resting HR 60.

• HRR = 185 − 60 = 125
• Zone 2 target = 60 + (125 × 0.60 to 0.70) = 60 + 75 to 87.5 = 135-148 bpm
• Zone 4 target = 60 + (125 × 0.80 to 0.90) = 60 + 100 to 112.5 = 160-172 bpm

The runner's HR distribution

For runners (or cyclists, swimmers), the gold-standard polarized training distribution is:

• ~80% of weekly volume in Zone 1-2 (easy, conversational pace)
• ~20% in Zone 4-5 (intervals, threshold work)
• Minimal time in Zone 3 ("the gray zone")

This 80/20 polarization is supported by 30+ years of endurance research. Most amateur runners do the opposite — too much Zone 3, not enough true Zone 2 or Zone 5. The result: chronic moderate fatigue without strong aerobic base development.

Zone 2 — the most underrated training

Zone 2 is the boring zone. You're moving slow enough to hold a conversation, your heart rate hovers around 60-70% HRR, you don't feel like you're training. It's the zone everyone wants to skip.

It's also the zone that builds:

• Mitochondrial density (your cells' energy factories)
• Fat-burning capacity
• Aerobic foundation that supports all higher-intensity work

If you can only do one type of cardio per week, do 40-60 minutes of pure Zone 2. The compound effect over months is dramatic.

The lifter's relationship to HR

Strength training doesn't fit cleanly into HR zones. During a heavy squat set, your HR can spike to 170+ bpm, then drop into Zone 2 during the rest period. A 60-minute lifting session might average Zone 2-3 — but the average hides the actual training stimulus, which is muscular and neural, not cardiovascular.

For lifters, HR is most useful for:

• Recovery monitoring. Resting HR trending up day-over-day is an early sign of overreaching or illness.
• Conditioning sessions. 1-2 dedicated cardio sessions per week to maintain heart health — done in Zone 2.
• HRV (heart rate variability) tracking. A more sophisticated recovery indicator some lifters use.

The "fat burning zone" myth

The label "fat burning zone" applied to Zone 2 isn't wrong — but the implication is misleading. Yes, the highest percentage of calories burned in Zone 2 comes from fat. But the total calories burned per minute is lower than higher zones. Net fat burned per workout is often higher in Zone 4 than Zone 2.

Zone 2 is valuable for cardiovascular adaptation and building aerobic base — not because it's a magic fat-burning intensity.

How to actually train zones (without obsessing)

For a fit adult who wants both strength and cardiovascular health:

• 3 strength sessions per week (45-60 min each)
• 1-2 Zone 2 sessions per week (40-60 min each — walking, easy cycling, easy jogging)
• Optional: 1 Zone 4-5 interval session per week (20 min including warm-up/cool-down)

That's it. Zones don't need to be precise. Listen to your body — Zone 2 is "I could do this all day" pace.