Meet the experts: Stacy Sims, PhD, is an exercise physiologist and the author of Roar: How to Match Your Food and Fitness to Your Female Physiology for Optimum Performance, Great Health, and a Strong, Lean Body for Life.

Athletes obsess over VO2 max because a higher measure means intense efforts can be sustained for longer, but you don’t need to be a pro to benefit from a higher VO2 max. Boosting this number can improve your fitness in ways that directly impact your daily life and workout performance. Here’s how:

• Easier cardio workouts: Ever feel winded walking up stairs or during the first few minutes of a run? A higher VO2 max helps your body use oxygen more efficiently, meaning you can sustain effort longer without feeling exhausted, says Sims.
• Better strength training endurance: If your heart rate spikes and you gas out quickly during circuit training, supersets, or HIIT, improving VO2 max can help you recover faster between sets and push through tough workouts.
• Increased energy in daily life: Your cardiovascular system plays a huge role in how energized you feel. A stronger VO2 max means your body delivers oxygen to muscles more effectively, which can translate to more stamina for everyday activities like chasing after kids, carrying groceries, or just staying alert throughout the day, says Sims.
• Improved recovery: A higher VO2 max supports faster recovery after workouts, so you’re less likely to feel wiped out after an intense session and can train more consistently, Sims says.
• Better overall health: Studies link higher VO2 max levels to lower risks of cardiovascular disease, metabolic issues, and even cognitive decline as you age. It’s one of the strongest indicators of long-term health and longevity, says Sims.

Testing VO2 max is where things get a little tricky. The most accurate way to measure it is in a lab setting, says Sims. This involves a cardiopulmonary exercise test (CPET), where you wear a mask and heart rate monitor while running on a treadmill or cycling on a stationary bike. The mask is hooked up to a machine that measures how much oxygen you inhale and how much carbon dioxide you exhale. As the intensity ramps up, your oxygen consumption eventually plateaus—that’s your VO2 max. The final number is recorded in mL/kg/min (milliliters of oxygen per kilogram of body weight per minute).

If you’re serious about getting an exact measurement, check if any gyms or performance labs near you offer VO2 max testing. But let’s be real—that’s not something most people are going to do.

A more practical way to estimate your VO2 max? A fitness tracker or smartwatch. Many devices, like the Apple Watch and Fitbit Ionic, calculate an approximation based on your heart rate and exercise intensity over time. Some brands even rebrand it—Fitbit calls it your ‘cardio fitness score,’ while Apple keeps it simple as VO2 max (you can find yours in the Apple Health app under ‘All Health Data’). For the average active person, this is the easiest way to track improvements without stepping into a lab.

There’s no perfect score for VO2 max—a desirable number really depends on your sport or main fitness activity, says Sims. Elite female cross-country athletes measure around 65 to 70 ml/kg/min, runners are about 60 to 65ml/kg/min, and cyclists are around 55 to 60 ml/kg/min, says Sims.

Generally speaking, though, this VO2 max chart notes where optimal scores should fall depending on your age:

Your cardio fitness level isn’t the only thing that plays a role. There are actually a number of internal and external factors that can have a major impact on your VO2 max, Sims says:

1. Genetics: Yep, just like with anything, genes are key to your VO2 max. ‘Genetics is said to play a 20 to 30 percent role,’ says Sims.
2. Age: ‘After the age of 25 VO2 max decreases by 1 percent a year,’ Sims says. ‘The good news is regular physical activity throughout life can offset much of the decline.’
3. Training volume: ‘Athletic training can alter a person’s VO2 max as much as 20 per cent depending on their lifestyle and fitness habits,’ says Sims. In other words, the more sedentary your lifestyle, the lower your VO2 max results will likely be.
4. Exercise mode of testing: The method of fitness used during a VO2 max test can also alter the findings—a treadmill test may yield different results than, say, cycling or swimming. ‘Treadmill running has been shown to produce the highest values,’ says Sims.
5. Gender: Since women are generally physically smaller than men, their VO2 max values are on average 15 to 30 percent lower, says Sims. ‘That’s because women have smaller hearts, lungs, and less hemoglobin, therefore, less oxygen uptake and delivery capacity.’
6. Body composition: A major reason for the differences in VO2 max between men and women is attributed to body composition, or the ratio of lean muscle mass to body fat. But that said, if you were to compare a woman and man with similar physical characteristics (age, training status, and body composition), there wouldn’t be a huge difference, says Sims. It’s also important to note that VO2 max decreases as body fat percent increases.
7. Altitude: If you’re high up in the mountains, your VO2 max will be different than at sea level. That’s simply because there is less oxygen to consume at higher altitudes, and as a result, your ability to take in oxygen decreases.

The best way to boost your VO2 max is through high-intensity interval training (HIIT)—workouts that push you to work hard for short bursts, followed by recovery. This kind of training improves your aerobic capacity by gradually increasing how efficiently your body uses oxygen, says Sims.

If you can track your VO2 max regularly, it can be a great way to gauge your fitness progress over time. The good news? You don’t need fancy equipment or elite-level training to improve it. Here are some simple ways to level up your VO2 max:

• Try HIIT workouts. Short, intense intervals (like sprinting for 30 seconds, then walking for 60) can help increase your aerobic capacity over time. Aim for two to three HIIT sessions per week, each lasting 20 to 30 minutes.
• Incorporate low-intensity steady-state (LISS) cardio. Longer, moderate-paced runs, swims, or cycles (think 45 to 60 minutes at a conversational pace) help improve endurance and heart health. Experts recommend two to four cardio sessions per week, depending on your training goals.
• Add incline or resistance. Walking or running on an incline or cycling with resistance forces your heart and lungs to work harder, building aerobic strength. Try one to two sessions per week, either as a dedicated workout or tacked onto a steady-state or HIIT session.
• Stay consistent. Training regularly, even at lower intensities, helps keep your cardiovascular system strong and improves your overall fitness. A mix of three to five aerobic training sessions per week—at varying intensities—will help keep your VO2 max trending upward, says Sims.

That said, while VO2 max is a useful metric in research and for elite athletes, Sims recommends not obsessing over it. Instead, focus on gradually pushing yourself in workouts to get fitter and faster.

Kristine Thomason is a writer and editor with nearly a decade of experience creating content for print and digital publications. Previously, she was the health and fitness director at mindbodygreen, and the fitness and wellness editor at Women’s Health. Kristine’s work has appeared in Men’s Health, Travel + Leisure, Health, and Refinery29, among others. She holds a journalism degree from New York University, and is certified in personal training by the National Academy of Sports Medicine (NASM).

Talene Appleton is the fitness editor at Women’s Health, where she nerds out over all things fitness, nutrition, and wellness. She was previously the fitness and commerce editor at Men’s Health, where she tested and reported on the newest, buzziest fitness and wellness products to hit the market. As a NASM-certified personal trainer and Precision Nutrition-certified nutrition coach, she is passionate about supporting women at the intersections of fitness, food, and community. Talene was on the George Washington University college dance team (shout out First Ladies) before moving on to become an NBA dancer for the Washington Wizards—you can still catch her at dance classes across New York and LA in her free time. Before entering journalism full-time, Talene was a private chef for four years and still enjoys cooking for and hosting friends and family regularly.