#293 - AMA #57: High-intensity interval training: benefits, risks, protocols, and impact on longevity
In this AMA, Dr. Peter Attia and co-host Nick Stenson clarify high-intensity interval training (HIIT), differentiating it from sprint interval training (SIT) and Tabata. They discuss its impact on VO2 max, the importance of a broad exercise portfolio, and how to define 'all out' efforts for longevity.
Deep Dive Analysis
6 Topic Outline
Introduction to High-Intensity Interval Training (HIIT)
Historical origins of interval training methods
Defining and differentiating HIIT from Sprint Interval Training (SIT)
Understanding 'all-out' effort and its duration limits
Methods for determining maximum heart rate
Discussing HIIT's perceived efficiency
6 Key Concepts
HIIT (High-Intensity Interval Training)
HIIT is typically defined by submaximal efforts, generally ranging from 80% to 95% of a person's maximum heart rate, with the goal of reaching the maximum aerobic training zone. The specific duration and intensity of intervals also determine the amount of anaerobic training achieved.
SIT (Sprint Interval Training)
SIT involves supramaximal efforts that exceed the output of a person's VO2 max. These are usually short, all-out bursts, typically lasting 10 to 60 seconds, performed at a higher power or speed level than what can be sustained at VO2 max, though not necessarily resulting in a higher heart rate due to the short duration.
Fartlek
Fartlek is a type of interval training, derived from Swedish meaning 'speed play,' which involves alternating between fast and slow running or other activities. This method was first employed by Finnish Olympic runners in the early 1900s and codified in the 1930s.
Tabata Training
Tabata training is a very specific interval protocol first described in the 1990s, consisting of eight sets of 20 seconds of all-out effort (e.g., on a bike) followed by 10 seconds of rest. This entire protocol lasts for a total of four minutes.
VO2 Max
VO2 max represents the maximal consumption of oxygen, achieved at a very high, but not necessarily peak, effort level. It is considered a very important metric for overall health and longevity, and sprint interval training efforts are designed to exceed the output of this maximal oxygen uptake.
Max Heart Rate
Max heart rate is the maximum achieved heart rate an individual can reach. While a simple formula (220 minus age) can predict it, the most accurate way to determine it is by pushing oneself in sub-maximal efforts until the maximum heart rate is actually achieved, typically during a VO2 max test or a stress test to failure.
4 Questions Answered
Interval training concepts date back to the 1800s with athletes altering tempo, becoming more codified in the early 1900s by Finnish Olympic runners, and terms like Fartlek (1930s) and Tabata (1990s) emerged later.
HIIT typically involves submaximal efforts (80-95% of max heart rate) targeting the maximum aerobic zone, while SIT involves supramaximal efforts that exceed VO2 max output, usually in short, all-out bursts (10-60 seconds) at higher power/speed.
According to Peter Attia, a true 'all-out' effort, where an individual pushes without any conscious or subconscious limitation, is generally only sustainable for up to about 10 seconds.
While a simple formula like 220 minus age can predict it, the most accurate way to know one's maximum heart rate is to actually push oneself in sub-maximal efforts until it is achieved, typically seen during a VO2 max test or a stress test to failure.
6 Actionable Insights
1. Broaden Exercise Portfolio
Do not focus solely on one type of exercise; instead, broaden your portfolio of exercise training to include a variety of activities for better longevity outcomes.
2. Demand HIIT Protocol Specificity
When discussing High-Intensity Interval Training (HIIT), ask for specific details regarding effort level, work duration, rest duration, and repetition frequency, as the term ‘HIIT’ itself is too broad and lacks a uniform definition.
3. Determine Max Heart Rate Accurately
To accurately know your maximum heart rate, push yourself in sub-maximal efforts until you reach it, or consider a VO2 max test or stress test, as the 220-minus-age formula is often insufficient.
4. Limit True “All Out” Efforts
Recognize that a truly ‘all out’ effort can only be sustained for approximately 10 seconds; for any duration longer than that, you are consciously or subconsciously applying a governor to your output.
5. Weekly VO2 Max Intervals
Integrate VO2 max intervals into your training routine once a week, aiming to reach near maximal heart rate by the end of each interval to improve this important longevity metric.
6. Use Robust Training Metrics
Consider basing your training intervals on RPE (Rate of Perceived Exertion), watts, speed, or METs, as these metrics may be more robust and accurate than solely relying on heart rate.
3 Key Quotes
When someone is talking to you about HIIT, ask them to stop using the language and just be specific, which is what is the effort level? What is the duration of work? What is the duration of rest? How often do I repeat it? How many times do I do it?
Peter Attia
The only effort in which you can truly go all out is an effort up to about 10 seconds.
Peter Attia
If you're doing anything over 10 seconds, you are consciously or subconsciously applying some governor to that activity that keeps you from absolutely blowing up.
Peter Attia
1 Protocols
Tabata Interval
Peter Attia (describing the protocol developed by Irsawa and described by Tabata)- Perform 20 seconds of all-out effort (e.g., on a bike).
- Rest for 10 seconds.
- Repeat this sequence 8 times.