What is the ideal duration (of sprint and rest) to increase vO2 max?

Effective VO₂ max intervals can use 20-second to 2-minute efforts, with rest matched to the effort—roughly 40 seconds to 3 minutes in the examples discussed.

• 20–30-second sprints: Rest about 40–60 seconds after 20-second bursts to preserve sprint quality; for 30-second efforts, rest can be around 30 seconds or longer, depending on the goal. 1 2
• 1-minute efforts: Rest 1–3 minutes between rounds. 3
• 2-minute efforts: One example uses 2 minutes of work, 2 minutes of rest, repeated for about three rounds. 4
• Weekly frequency: Aim for at least once weekly, with twice weekly better; avoid pushing hard intervals too frequently if fatigue or recovery becomes a problem. 5

Keep the efforts genuinely intense while maintaining safe, good form; longer efforts generally require more recovery. 6