How long does it take to improve VO2 max?

Most people see measurable change in eight to twelve weeks of consistent training that includes both easy volume and one weekly interval session.

Is a 4x4 interval session good for VO2 max?

Yes. Four intervals of four minutes hard with three minutes easy between them is a well established and effective structure. Once a week is plenty alongside other training.

Can strength training improve VO2 max?

Indirectly. Strength work improves running economy, so you use less oxygen at a given pace. That improves endurance performance even when the VO2 max number itself moves little.

ENDURANCE

How do you improve VO2 max after 40?

Build mostly easy aerobic volume, then add one hard interval session per week using three to five minute efforts at a pace you could hold for about ten minutes. That combination raises VO2 max at any age. What stalls people after 40 is doing everything at medium intensity.

ANSWERED BY SELINA LEBLANC · UPDATED AUGUST 11, 2026

VO2 max is the ceiling on how much oxygen you can use during hard effort. It tends to decline with age, and it is one of the markers most consistently linked to long-term health outcomes. It also responds well to training at every age.

The two ingredients

Easy volume. Three or more sessions a week where you could hold a conversation. This builds the plumbing: capillaries, mitochondria, stroke volume. It is unglamorous and it is most of the work.

One hard interval session. Three to five minute intervals at roughly your ten minute race pace, with equal or slightly shorter recovery. Four to six of them. That is a full session and it is enough. A common alternative is a set of 4x4 minute efforts with three minutes easy between.

The mistake after 40

Most of the week ends up in the middle. Runs are too hard to recover from and too easy to drive adaptation, and the hard session then has to be done tired. Split the intensity properly and the same weekly hours produce more.

Measuring it without a lab

Run a 5K time trial. Plug the time into a VDOT-style estimate. The number matters less than the trend, so use the same route or track, the same warm up and similar conditions, and retest every eight to twelve weeks.

What else moves the number

Consistency over months, not weeks. This adapts slowly.
Enough carbohydrate to actually complete the hard session.
Strength training, which improves running economy so you use less oxygen at the same pace.
Sleep, because interval sessions performed exhausted are just fatigue with extra steps.

A realistic weekly shape

2 to 3 easy aerobic sessions
1 interval session
2 strength sessions
Walking on top of all of it