What is the recommended plan for High-Intensity Interval Training (HIIT) sessions?

HIIT Session Planning Guidelines

HIIT sessions should involve aerobic training at 65-90% VO2peak or 75-95% heart rate peak for intervals of 10 seconds to 4 minutes, with 12 seconds to 5 minutes of active or passive recovery between intervals, performed 3-5 times per week with total intense exercise time of ≤10 minutes per session within a 30-minute total time commitment including warm-up and cool-down. 1

Core HIIT Session Structure

The fundamental HIIT prescription consists of:

• Frequency: 3-5 sessions per week, with at least 3 sessions being the minimum effective dose 2, 3
• Intensity: Work intervals at 65-90% VO2peak or 75-95% of maximum heart rate (calculated as 220 minus age) 1
• Work interval duration: 10 seconds to 4 minutes of high-intensity effort 1
• Recovery interval duration: 12 seconds to 5 minutes of active (low-intensity movement) or passive (complete rest) recovery 1
• Total intense exercise time: ≤10 minutes of actual high-intensity work per session 2
• Total session time: ≤30 minutes including warm-up, intervals, recovery periods, and cool-down 2

Intensity Calibration Methods

Use multiple methods simultaneously to ensure appropriate intensity:

• Heart rate targets: 75-95% of maximum heart rate, though this requires validation as medications can alter heart rate response 1, 3
• Borg RPE scale: Target score of 14-16 (breathing very hard, incompatible with carrying on conversation comfortably) during work intervals 1
• Talk test: During work intervals, breathing should be too hard to speak full sentences 1
• Subjective effort: Work intervals should feel "vigorous" to "very hard" 3

The American Diabetes Association emphasizes that higher intensities of aerobic training are generally superior to low-intensity training for metabolic adaptations 1. However, individual calibration using both objective (heart rate) and subjective (RPE, talk test) measures is essential for safe and effective prescription 3.

Progression Strategy

Follow this stepwise progression:

1. Initial phase (weeks 1-2): Start with shorter work intervals (10-30 seconds) at the lower end of intensity (65-75% VO2peak), with longer recovery periods (2-3 minutes) 1, 3
2. Intermediate phase (weeks 3-6): Gradually increase work interval duration (30 seconds to 2 minutes) and intensity (75-85% VO2peak), while maintaining or slightly reducing recovery time 3
3. Advanced phase (weeks 7+): Progress to longer work intervals (2-4 minutes) at higher intensities (85-90% VO2peak) with shorter recovery periods (1-2 minutes) 1, 3

The American Diabetes Association notes that medical monitoring may be indicated as individuals intensify their exercise program to ensure safety 1.

Critical Safety Considerations

Mandatory pre-HIIT assessment must identify:

• Autonomic neuropathy: Can cause exercise-induced blood pressure instability during high-intensity intervals 4
• Orthostatic hypotension: Worsens with intense exercise demands and rapid transitions between work and recovery 4
• Uncontrolled hypertension: Poses cardiovascular risk during high-intensity intervals 4
• Balance impairment: Increases fall risk during vigorous activity 4
• Decreased exercise tolerance or atypical cardiovascular symptoms: May indicate underlying cardiovascular disease 4

The American College of Cardiology warns that HIIT can trigger arrhythmias through sympathetic-vagal imbalance during high-intensity intervals, and rapid blood pressure fluctuations between work and recovery intervals can worsen dizziness 4.

When HIIT Should Be Avoided

Do not prescribe HIIT until:

• All cardiovascular risk factors have been evaluated and controlled 4
• Dizziness or unexplained symptoms have been fully investigated 4
• Patient demonstrates tolerance to moderate-intensity continuous exercise 4

The American Diabetes Association recommends starting with short periods of low-intensity exercise and slowly increasing duration and intensity in patients with high cardiovascular risk or unexplained symptoms before considering HIIT 4.

Practical Session Examples

Beginner HIIT protocol (weeks 1-4):

• 5-minute warm-up at low intensity
• 8 intervals of 30 seconds at 75% maximum heart rate
• 2 minutes active recovery (light walking/cycling) between intervals
• 5-minute cool-down
• Total session time: 28 minutes 2, 3

Intermediate HIIT protocol (weeks 5-8):

• 5-minute warm-up
• 6 intervals of 1 minute at 80-85% maximum heart rate
• 90 seconds active recovery between intervals
• 5-minute cool-down
• Total session time: 25 minutes 3

Advanced HIIT protocol (weeks 9+):

• 5-minute warm-up
• 4 intervals of 4 minutes at 85-90% maximum heart rate
• 3 minutes active recovery between intervals
• 5-minute cool-down
• Total session time: 30 minutes 1, 3

Monitoring During Sessions

Track these parameters throughout:

• Heart rate during work and recovery intervals to ensure target zones are achieved 3
• RPE scores at the end of each work interval (should be 14-16) 1, 3
• Blood glucose before and after sessions in patients with diabetes (HIIT can cause transient post-exercise hyperglycemia) 1
• Any symptoms of dizziness, chest discomfort, or excessive breathlessness that doesn't resolve during recovery 4

Common Pitfalls to Avoid

Critical errors that compromise effectiveness or safety:

• Insufficient intensity during work intervals: If patients can speak comfortably, intensity is too low 1
• Inadequate recovery between intervals: Recovery periods are essential for maintaining high intensity in subsequent work intervals 1
• Excessive total session volume: More than 10 minutes of actual high-intensity work negates the time-efficiency benefit and increases injury risk 2
• Skipping warm-up or cool-down: These are essential components of the 30-minute session structure 2
• Using predicted maximum heart rate alone: Must validate with subjective measures (RPE, talk test) as medications and individual variation affect heart rate response 3

The European Society of Cardiology notes that aerobic interval training and high-intensity interval training cannot yet be broadly recommended until further data on safety and efficacy are available for all populations, emphasizing the importance of individualized assessment 1.