VO2max and heart rate are related, but not the same. VO2max is the amount of maximal oxygen the body can take during exercise requiring near-maximal or maximal exertion/effort. Heart rate on the other hand is the rate at which your heart beats per minute. There is a positive correlation between heart rate and oxygen consumption—the closer you are to your maximal heart rate, the closer you are to your VO2max.
So when you are doing interval training, you are going at (near) maximum heart rate and (near) maximum VO2max during the high intensity intervals.
High VO2max and a low resting heart rate are both associated with good cardiovascular fitness. Here are two charts from TopEndSports showing Vo2max levels for men and women in certain age ranges:
Not surprisingly, your VO2max decreases as you age and thus the criteria for what is considered “average” or “excellent” also decreases.
VO2max measures lung efficiency, resting heart rate measures how efficiently your heart works. Both need to be efficient in order for you to be healthy. The higher your VO2max is, the better. The lower your resting heart rate is, the better.
****Resting heart rate is your heart rate when you are just sitting down and not exerting physically exerting yourself in any way. It is measured in bpm (beats per minute).
The resting heart rate has a big range for what is considered “normal.” Another chart from TopEndSports shows the average resting heart rate for men and women:
What is interesting from the chart is that the resting heart rate doesn’t change too much as you age, unlike the chart for VO2max. A good resting heart rate is the same for someone who is 20 as it is for someone who is 60. The same cannot be said for VO2max.
Although that is the typical range, there are a lot of things that can potentially increase or decrease your heart rate. My resting heart rate will jump 10 beats per minute if I drink coffee or have a stimulant in my system.
So what is a better indicator of fitness, VO2max or heart rate? That depends. If you are talking about fitness in terms of how well your heart works, heart rate is a better indicator of heart health. VO2max is a better indicator of your ability to exert yourself physically. But both are reliable indicators of overall health and well-being; to maintain good physical health, maintain a high VO2max and a low resting heart rate.
Figuring Out Your VO2max from Your Heart Rate
Figuring out your VO2max accurately is very expensive. But there is a way estimate your VO2max, given the linear relationship between the two numbers. As you get closer to your VO2max, you will also get closer to your maximum heart rate. According to the American College of Sports Medicine, exercise at 60 percent of VO2 max corresponds with a heart rate that is 75 percent of maximum, and exercise at 80 percent of VO2 max corresponds with 88 percent of maximum heart rate.
Here is a site that lets you estimate your VO2max based off of your heart rate. If you know your maximum heart rate (via a stress test or other means), then just plug that number into the calculator. If you do not know what your maximum heart rate is, use the formula:
217 – (.85 x Age)=max heart rate
Increasing VO2max and Decreasing Resting Heart Rate
If you are not happy with your resting heart rate and your VO2max, then easiest way to improve the two is to do steady-state cardio. But the most effective way to improve the two numbers is by doing 2-3 days steady-state cardio mixed with 2-3 days of intense (but short) sessions of HIIT per week. Other great ways of decreasing resting heart rate are yoga and meditation, which have some of the same stress-releasing elements.