What can I do to improve my VO2 max?
- Jul 27
- 3 min read
Should I train at high or low intensity?
Recent studies show that aerobic exercise improves VO2 max across nearly all exercise intensities [1]. There's no “one size fits all” approach. However, if you're optimizing for the largest gains in the least amount of time, the type of training you choose does matter.
High-Intensity Training (HIT) and Low-Intensity Training (LIT) are the two most commonly referenced training intensities used to improve VO2 max. HIT is generally defined as bouts above 80% of your VO2 max, while LIT falls below that threshold [1].
Within these two categories are three commonly prescribed training styles: Moderate-Intensity Continuous Training (MICT), High-Intensity Interval Training (HIIT), and Sprint Interval Training (SIT).
MICT means steady-state exercise at a moderate effort level (about 50–80% of your VO2 max) for a longer period of time [1]. Think of a steady jog, or a bike ride at a conversational pace.
HIIT is a form of interval training that alternates between higher- and lower-intensity exercise. The hard stretches push you to a high intensity, roughly 80–170% of your VO2 max, and should last up to 4 minutes [1]. Note: any value above 100% corresponds to the short, intense bursts, when your muscles need energy faster than oxygen can be delivered. The recovery periods are lower intensity, typically around 40–50% of your VO2 max, and can range from equal to several times the length of the work interval. Picture alternating fast aerobic exercise, such as running, rowing, or cycling, followed by walking or a low-intensity recovery period.
Norwegian 4x4
Try running, rowing, or cycling 4 rounds of 4 minutes hard, with 3 minutes of easy recovery between each. This is a well-studied HIIT protocol known as the Norwegian 4x4 [2].
SIT is similar to HIIT but even more intense. It involves all-out effort, up to and/or exceeding 170% of your VO2 max, capping at 30 seconds [1]. Think of any maximal, all-out sprint in the non-contact endurance sport of your choosing.
Each of these approaches, LIT (MICT) and HIT (HIIT/SIT), has been shown to improve VO2 max across most populations meaningfully: young, elderly, active/athletic, and sedentary [1]. Your current fitness baseline is what should inform the most practical regimen for you.
So, what should you actually do?
If you're new to training, start with 2–3 sessions of MICT per week: 20–40 minutes of steady effort you could sustain while holding a conversation. This builds an aerobic base with a low risk of injury and is easy to stick with.
Once you have that foundation (typically after 4–6 weeks of consistent training), add 1–2 HIIT sessions per week. For example, 4–5 rounds of 3–4 minutes of high-intensity exercise, with 2–3 minutes of easy recovery in between. This is where you'll see the fastest VO2 max gains [3]. In fact, HIIT has been shown to produce significantly greater VO2 max improvements than steady-state training alone [4].
If you're already active and want to push your ceiling further, SIT can be layered in sparingly, once a week at most. Short, all-out efforts including 6–8 rounds of 20–30 seconds, with several minutes of rest between. Because SIT is so taxing, more isn't better here; overdoing it increases injury and burnout risk without added benefit.
Whatever your training approach, tracking your progress is what turns effort into results. Want to see how your VO2 max is actually responding to training, not just estimate it? Sign up to be an AeroCardia beta user here.
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