⌚ Activity Tracker Comparison

What It Measures

⚠️ Where They Go Wrong

• Calories — the most overestimated metric; the device cannot know your metabolism.
• Heart rate during exertion — the tracker moves and you sweat, which impairs optical measurement; a chest strap is more accurate.
• Sleep phases — even laboratory methods are complex; the tracker often confuses rest with sleep.
• Steps — may count movements that are not steps (e.g., manual work).
• Absolute HRV value not comparable between people; only a personal trend is meaningful.

✅ How to Use Wisely

• Look at trends, not a single day's number — a weekly average is more meaningful than yesterday.
• Use it as a reminder to move, not as a judge — the device cannot see whether you are tired.
• Assess Sleep by How You Feel and regularity, not just by the score.
• Heart Rate During Exercise it is better to track with a chest strap if it matters (see heart rate zones).
• Don’t Chase the „10 000 Steps" Dogma — There is evidence of benefits at a lower number too; regularity matters more.
• Don’t Track Too Much: constant measuring can cause anxiety and harm your training.

🙋 Frequently Asked Questions

Will a Tracker Replace a Coach? No — it provides data, but interpretation and planning require knowledge.

Is an Expensive Device Worth It? Usually a modest one is enough: steps, heart rate, and sleep are the main metrics.

Can You Trust Calories? Use them as a guide, not as fact — counting food calories is more reliable (see calorie search).