Is it better to increase heart rate higher for longer periods of time during exercise?

Exercise Heart Rate Strategy

For general exercise training, maintaining heart rate at moderate intensities (60-80% of peak heart rate or heart rate reserve) for sustained periods is superior to pushing heart rate higher, as this optimizes cardiovascular adaptation while minimizing cardiac stress and adverse events. 1

Optimal Heart Rate Targets by Population

Healthy Individuals

• Target 60-80% of heart rate reserve or peak VO2 for aerobic training sessions lasting 8-12 minutes or longer 1
• Exercise protocols should be designed to last 8-12 minutes to peak exercise, as shorter but more aggressive protocols may not allow sufficient time to measure full physiological response 1
• Heart rate increases approximately 10 bpm per metabolic equivalent (MET) during normal exercise 1

Heart Failure Patients

• Training heart rate should be kept as low as possible while still achieving peripheral training stimulus 1
• Target rating of perceived exertion <13 ("somewhat hard") on the Borg scale 1
• Interval training is preferable because it allows high peripheral exercise stimuli without significant heart rate increases 1
• Interval training produces similar mean arterial blood pressure and heart rate compared to steady-state exercise at the same average power output, but with greater peripheral training stimulus 1

Patients with Left Ventricular Dysfunction

• Optimal maximum heart rate is 75% of age-predicted maximum in patients with ejection fraction ≤45% 2
• In patients with normal ejection fraction (≥55%), optimal upper rate limit is 86% of age-predicted maximum 2
• Exceeding these thresholds can lead to tachycardia intolerance and worsening cardiac function 2

Why Lower Heart Rates for Longer Duration Are Better

Cardiovascular Protection

• Long-term reduction in heart rate is of major importance for myocardial recovery, associated with improved diastolic function and myocardial metabolism 1
• In heart failure patients, impaired force-frequency relationship means higher heart rates do not translate to better cardiac performance 1
• Lower heart rate difference (maximal minus resting heart rate) predicts higher cardiovascular mortality risk, particularly in high-risk individuals 3

Physiological Rationale

• Stroke volume increases normally during initial exercise phases, then plateaus; further cardiac output increases rely primarily on heart rate 1
• Excessive heart rate elevation imposes primarily a pressure load on the cardiovascular system rather than optimal volume conditioning 1
• At very high heart rates, diastolic filling time decreases, potentially compromising stroke volume and cardiac output 1

Specific Training Recommendations

Steady-State Exercise

• Intensity: 40-80% of peak VO2 for most populations 1
• Lower intensities (40-50%) can be compensated by longer duration or higher frequency 1
• Duration: 10-60 minutes per session, depending on baseline functional status 1
• Frequency: 3-7 times per week based on individual capacity 1

Interval Training (Preferred for Limited Patients)

• Allows more intense peripheral muscle training without excessive cardiac stress 1
• Work phases: 30-60 seconds at higher intensity 1
• Recovery phases: 60 seconds at minimal intensity 1
• Mean heart rate and blood pressure similar to steady-state, but greater peripheral adaptation 1

Critical Safety Considerations

Termination Criteria

• Exercise must be terminated when acute blood pressure decrease, angina, significant dyspnea/fatigue, exhaustion, or serious arrhythmias occur 1
• Achievement of 85% age-predicted maximal heart rate should NOT be used as sole termination criterion due to high inter-individual variability (±10-12 bpm) 1
• Systolic blood pressure increase of only 10-20 mmHg may be acceptable if no concomitant symptoms develop 1

Population-Specific Warnings

• Heart failure patients with abnormal V̇E/V̇CO2 slope >34 have increased mortality risk; exercise intensity must be carefully monitored 1
• Patients on beta-blockers have altered heart rate responses; percentage of peak heart rate becomes less reliable for intensity prescription 1
• Cardiac transplant recipients require slow workload increases due to denervated heart response to circulating catecholamines 1

Common Pitfalls to Avoid

• Do not use age-predicted maximum heart rate formulas rigidly (220-age has ±10-12 bpm variability) 1
• Do not assume higher heart rate equals better training effect—this is particularly dangerous in heart failure and left ventricular dysfunction 1, 2
• Do not ignore heart rate recovery—abnormal recovery (slow decline post-exercise) is an independent predictor of mortality 1
• In atrial fibrillation patients, 45% exceeded age-predicted maximal heart rate during exercise, indicating poor rate control 4