Target Heart Rate

Your target heart rate is a range of numbers that reflect how fast your heart should be beating during aerobic exercise to achieve maximum cardiovascular benefit safely.

The Karvonen Formula

While the simple 220 - Age formula gives a rough estimate of maximum heart rate, it doesn't account for individual fitness levels. The Karvonen formula is much more accurate because it factors in your Resting Heart Rate (RHR).

Step 1: Heart Rate Reserve (HRR)

$\text{HRR} = \text{Max Heart Rate} - \text{Resting Heart Rate}$

Step 2: Target Zone Calculation

To find the beats per minute (BPM) for a specific intensity percentage ($I$):

$\text{Target HR} = (\text{HRR} \times I) + \text{Resting Heart Rate}$

Training Zones

Depending on your fitness goals, you should aim for different intensity percentages:

• Warm Up / Recovery Zone (50-60%): Ideal for warming up, cooling down, or active recovery.
• Fat Burning Zone (60-70%): The body primarily uses fat stores for energy. Good for endurance building.
• Aerobic Zone (70-80%): Improves cardiovascular fitness, lung capacity, and stamina.
• Anaerobic Zone (80-90%): High-intensity training. Improves lactate threshold and performance.
• VO2 Max / Redline (90-100%): Maximum effort. Only sustainable for very short bursts.

Frequently Asked Questions

How do I measure my resting heart rate?

The best time to measure your resting heart rate is first thing in the morning, before getting out of bed. Place two fingers on the inside of your wrist or your neck, count the beats for 30 seconds, and multiply by two.

What if my heart rate goes above my target zone?

If you are consistently above your target zone and feel breathless, dizzy, or nauseous, slow down immediately. If you feel fine but are above the zone, your actual maximum heart rate might be higher than the standard formula estimates.

Do fitness trackers measure heart rate accurately?

Modern chest-strap heart rate monitors are incredibly accurate (akin to an EKG). Wrist-based optical sensors (like an Apple Watch or Fitbit) are generally very good for steady-state cardio but can lag or lose accuracy during high-intensity interval training (HIIT) or weightlifting.