What Do VO2 Max, Lactate Threshold, and Other Common Running Terms Really Mean?

As a runner, you have probably heard terms like VO2 max and lactate threshold. But what do they mean, and how do they influence your running performance?

VO2 Max

Your VO2 max, or aerobic capacity, means the highest amount of oxygen your body can consume and use during hard exercise. People with high VO2 max are often fitter and have a lower risk of health problems like heart disease, diabetes, and some types of cancer.

Your VO2 max depends on how well your lungs, heart, and blood deliver oxygen to your muscles, and how well your muscles use that oxygen for energy during exercise. Though genetics play a big role in determining whether you have a high VO2 max, it’s possible to improve with regular, structured training. People with higher VO2 max can run faster and farther with less effort than those with lower VO2 max.

Metabolic Efficiency

Metabolic efficiency means how your body uses energy during exercise. At low to moderate intensities, your body mostly burns fat for energy. As you go faster and work harder, your body starts to use more carbohydrates for fuel. Most people have a lot of stored fat that can be used for energy during easy exercise, but only about 1,500 calories of stored carbohydrates for harder efforts.

Given that running a marathon requires about 3,000 calories for most people, it is important that runners can tap into fat stores for energy during the low- to moderate-intensity portions of the race. This allows your body to reserve carbohydrates the more challenging stretches, such as bridges and hills. This will decrease your need to eat or drink during the tougher parts of the race.

Lactate Threshold

Lactate threshold is about how your body deals with lactate, a substance made when you exercise hard. As you work out harder, your muscles make more lactate. At first, your body can use or get rid of it. But when the exercise gets even tougher, your body can’t keep up, and lactate starts to build up faster than your body can handle. This buildup also makes your muscles feel tired and makes it hard to keep going.

There are two main signs that show how your body handles lactate. The first one is called the aerobic threshold. This is the point where your body starts to make more lactate, but your muscles can still mostly use oxygen for energy. The second is called the anaerobic threshold. This is when your body makes even more lactate, and your muscles can't keep up, so they have to get more energy without using oxygen. Training can help raise these thresholds, so you can exercise harder for longer before getting tired.

Running Economy

Running economy is about how much oxygen your body uses when you run at different speeds. If you have good running economy, you use less energy to run at the same pace. This means you can run longer and faster without getting tired as quickly. Running economy is measured by how much oxygen you need at a certain speed; using less means you are more efficient. Things like how your foot hits the ground, how much you bounce up and down, your muscle strength, and how you control your movements all affect your running economy.

You can improve running economy by working on your running form and strength. One simple measure is your step rate, or cadence. Many experts suggest aiming for 170 to 180 steps per minute when you run.

If you would like to learn more about your own stats, how they impact your running, and how to improve them through training, a metabolic assessment and running mechanics analysis with an exercise physiologist is the place to start.