What is the optimal number of high-intensity interval training (HIIT) sessions per week for maximum improvement in maximum oxygen uptake (VO2 max)?

From the Guidelines

The optimal number of high-intensity interval training (HIIT) sessions per week for maximum improvement in maximum oxygen uptake (VO2 max) is 3 times per week.

Key Points

• The evidence from studies 1 suggests that HIIT can be an effective way to improve VO2 max, particularly in patients with heart failure.
• A study by Angadi et al. 1 found that HIIT improved peak VO2 by 22% compared to moderate continuous training (MCT) which improved peak VO2 by 11%.
• Another study by Donelli da Silveira et al. 1 also found that HIIT improved peak VO2 and diastolic function in patients with heart failure with preserved ejection fraction (HFpEF).
• The American Heart Association and American College of Cardiology recommend supervised exercise training, including HIIT, for patients with chronic heart failure 1.
• The European Heart Journal guidelines recommend aerobic training, including HIIT, at a frequency of at least 3 days/week, preferably 6–7 days/week, at moderate or moderate-to-high intensity 1.

Important Considerations

• The intensity and frequency of HIIT should be individualized based on the patient's preferences, abilities, and medical condition.
• HIIT can be prescribed in selected patients for specific targets of intervention, such as increasing VO2 peak 1.
• The evidence suggests that HIIT can be a safe and effective way to improve VO2 max, but more studies are needed to examine the effects of HIIT on clinical events in patients with heart failure 1.

From the Research

Optimal Number of HIIT Sessions per Week

The optimal number of high-intensity interval training (HIIT) sessions per week for maximum improvement in maximum oxygen uptake (VO2 max) is not explicitly stated in the provided studies. However, the studies suggest that:

• 6 HIIT sessions over 5 days can be as effective as 6 HIIT sessions over 2 weeks in increasing VO2 max and endurance capacity 2
• 2 HIIT sessions per week, in addition to 2 recovery run sessions, can lead to significant improvements in VO2 max, lactate threshold, and 3000 m running performance 3
• 10 sessions of HIIT can result in significant improvements in VO2 max and cardiac output 4
• The degree of change in VO2 max induced by HIIT can vary depending on the protocol, with short-intervals, low-volume, and short-term HIIT eliciting beneficial effects, while long-interval, high-volume, and moderate to long-term HIIT displaying larger effects 5

Key Findings

• HIIT can be an effective way to improve VO2 max, with significant improvements seen in as little as 6 sessions 2
• The intensity and volume of HIIT can impact its effectiveness, with high-intensity aerobic interval training resulting in significantly increased VO2 max compared to moderate training 6
• The frequency of HIIT sessions can also impact its effectiveness, with 2-3 sessions per week resulting in significant improvements in VO2 max and other physiological variables 3, 4

Protocol Considerations

• The protocol used in HIIT can impact its effectiveness, with different protocols resulting in varying degrees of improvement in VO2 max 5
• The duration and intensity of HIIT sessions can also impact its effectiveness, with longer and more intense sessions resulting in greater improvements in VO2 max 3, 4