You finish a run and your training partner, who started at the same pace, still seems fresh while you are out of breath. The difference often comes down to a single physiological parameter: VO2 max, which is the maximum amount of oxygen your body can use during intense effort. Improving this capacity significantly changes your endurance, speed, and recovery.
Aerobic durability: the factor that VO2 max alone does not measure
VO2 max indicates your oxygen ceiling. But running a half-marathon or a trail is not about staying at the ceiling for two hours. What matters is the percentage of VO2 max that you can maintain over time.
Physical trainers specialized in trail running refer to “durability” to describe this capacity. A runner with a modest VO2 max but capable of utilizing a high fraction of it for a long time will often outperform a runner with a higher ceiling who collapses after forty minutes.
In practical terms, working on durability means accumulating volume at a moderate pace, between the aerobic threshold and the anaerobic threshold. Long runs at marathon pace, for example, train your body to recycle lactate and conserve glycogen. To read Carnet de Sportive’s tips on techniques that combine these two aspects, it’s a good starting point.
Improving your endurance relies as much on durability as on the VO2 max ceiling. Before multiplying interval sessions, ensure that your aerobic base is solid.
Interval sessions to increase VO2 max in running
Interval training remains the most direct lever to push your oxygen consumption higher. The principle is simple: alternate phases of effort close to maximum with short recovery phases that prevent complete rest.
How to structure an effective session
You may have noticed that a 30/30 (thirty seconds fast, thirty seconds slow) leaves you breathless differently than a 3-minute fast followed by 2 minutes slow? Both formats engage VO2 max, but not in the same way.
- Short intervals (30 seconds to 1 minute of effort, equal recovery) allow you to accumulate time at high intensity without excessive muscle fatigue, which is well-suited at the beginning of a cycle or after a break.
- Long intervals (3 to 5 minutes of effort at VMA pace, 2 to 3 minutes recovery) force the cardiovascular system to maintain a high oxygen flow for longer, which further stimulates cardiac adaptation.
- Mixed sessions (pyramid: 1 min, 2 min, 3 min, 2 min, 1 min) provide variety and train the body to manage changes in pace, useful for competitive running.
Two interval sessions per week are sufficient for progress. Beyond that, the risk of overtraining increases without proportional benefit.
Finding the right working pace
The target pace corresponds to your VMA (maximum aerobic speed). If you don’t know it precisely, use a simple benchmark: the effort at which you can no longer hold a conversation, but where you are not sprinting either. On a perception scale of 1 to 10, aim for 8.
Running too fast turns the session into pure anaerobic work. You produce a lot of lactate, your muscles saturate quickly, and the time spent at high oxygen consumption decreases. The result: more fatigue, less stimulus on VO2 max.
Recovery and training after 55: adapting the load to progress
VO2 max naturally declines with age. This decline is not linear and heavily depends on the level of activity maintained. What really changes after 55 is the recovery speed between sessions.
Trail trainers recommend limiting intense sessions to two per week, spaced at least 48 hours apart. While a 30-year-old runner can assimilate a tough session in 48 hours, an older runner often needs 72 hours for the same level of adaptation.
The progression of load should not exceed about 10% per week, whether in volume or intensity. Respecting this pace allows you to continue working at intensities that stimulate VO2 max without accumulating fatigue that leads to injury or stagnation.
Why is this point often overlooked? Because generic training programs do not distinguish between age groups. A plan to “improve VO2 max in 8 weeks” that suggests three interval sessions per week is suitable for a thirty-year-old, not a fifty-year-old. Adapting the load is as important as the content of the sessions.
Smartwatches and estimated VO2 max: what the displayed numbers really mean
Garmin, Polar, and other brands display an estimated VO2 max based on heart rate and running pace. These tools even provide daily suggestions that adjust the recommended intensity based on your history.
This estimation has a clear limit: it relies on algorithms that model the relationship between heart rate and oxygen consumption. However, this relationship varies according to heat, fatigue, hydration, elevation, and even stress. A run in 35-degree weather will drop your estimated VO2 max without your actual capacity changing.
Use the trend over several weeks, not the value of a single session. If your estimated VO2 max progresses regularly over a month, your training is working. A temporary drop after a busy week or a short night means nothing.
For those wanting a reliable measurement, laboratory testing with a gas analyzer remains the gold standard. It also allows for precise determination of your ventilatory thresholds and VMA, two data points that calibrate your sessions with much more accuracy than an algorithm embedded in a wristwatch.
Progressing in VO2 max is not just about running faster more often. The combination of well-measured intervals, sufficient aerobic volume, and recovery tailored to your profile produces lasting results. The best indicator of progress remains your feeling on the ground: if the pace that left you breathless three months ago becomes comfortable, your aerobic capacity has indeed improved.