Heart Rate Variations: Resting, Maximum, and Target Zones Explained

Key Heart Rate Metrics

• Resting HR (RHR): Beats/min at complete rest (supine, morning). Normal: 60–100 bpm. Athletes: 40–60 bpm. ↓ with fitness, ↑ with age, stress, illness, meds (β-blockers ↓, stimulants ↑).
• Maximum HR (MHR): Highest achievable. Estimated: 220 – age (rough). Measured: graded exercise test. Declines ~1 bpm/year.
• Target HR Zone: %MHR for training goals:
  • Moderate: 50–70% MHR
  • Vigorous: 70–85% MHR
  • High-intensity interval: >85% MHR
• Heart Rate Reserve (HRR): MHR – RHR. Karvonen formula: Target = RHR + % × HRR (more individualized).

Influencing Factors

• Age, sex (women ~5–10 bpm higher RHR), fitness, medications, hydration, temperature, altitude, emotions, time of day.

Clinical Red Flags

• RHR consistently >100 or <50 (if not athlete)
• Irregular rhythm (palpitations, skipped beats)
• Exaggerated/exercise intolerance
• Syncope, near-syncope

Monitoring

Wearables (PPG) convenient but less accurate than ECG/chest strap, especially during motion. Clinical decisions require medical-grade data.