How Vigorous Exercise Improves VO2 Max and Heart Function

This audience here probably already knows this, but this is the kind of exercise where you're really not able to have a conversation because you're working hard and cannot comfortably talk. And if you're wearing a heart rate monitor, you're somewhere around 80 percent of maximum heart rate or higher. So, that's the kind of exercise that I'm really going to be focused on mostly for the next part of my talk. If you could put it in a pill, it'd be the biggest blockbuster anti-aging drug ever. But no one's going to be able to do that because it's doing too many things. One thing it does is improve cardiorespiratory fitness. Cardiorespiratory fitness is so important for the way we age. It's measured often by something called VO2 max. That's the maximum amount of oxygen you can take up during maximal exercise. And why is it so important? Well, because we need to be able to move oxygen throughout our tissues and transport it to our organs to be able to live, right? And if you think about cardiorespiratory fitness, for me to stand on this stage and have a conversation takes about 11 milliliters per kilogram of body weight per minute. That is the demand of standing still and speaking. It takes about 3.5 milliliters per kilogram of body weight per minute to sit and breathe. To do anything else, it's going to be way more than that, right? And if you're talking about maximal exercise, you're going to get much higher. Some older adults become breathless while walking to their car or doing everyday activities. They do not have high cardiorespiratory fitness and that's not good because we all are going down and reaching this cliff. We will all get to that cliff as we're aging. And when we get to that cliff, everything becomes a maximal effort. At that point, just sitting and breathing becomes a maximal effort, and you don't want that. So what you want is to bank and get your VO2 max as high as you can because you want to be way high up when you're going down the cliff. That way you have a lot longer way to go to get to that cliff. Studies show that any increase from below-normal fitness is beneficial. So even if you go from below normal to low normal, that's associated with a 2-year increase in life expectancy. If you go up to the high where you're going above the normal, that's a 5-year increase in life expectancy. Researchers calculated a dose-dependent association: every 1-milliliter-per-kilogram-per-minute increase in VO2 max correlates with a 45-day increase in life expectancy. So you're adding 45 days to your life for every unit increase in your VO2 max.

There's a JAMA study that was published not too long ago, a couple years back that I really like to talk about because it examined a range of cardiorespiratory fitness levels in a population of veterans and found that those participants with the highest VO2 max had a 5-year increase in life expectancy compared with people in the lowest group. They were actually 80% less likely to die from all causes of mortality compared to people in the lowest cardiorespiratory group. The elite group, those in the top 2% for VO2 max, still had a 20% increase in life expectancy compared with the fit group in the top 25%. So in other words, the conclusion was that there was no observed limit to the mortality benefit if you keep increasing your VO2 max. And I just mentioned there was a calculation, right? 45 days for every unit. So there you go. Makes sense. But what I really like about this study actually isn't that. It's that what was found was low cardiorespiratory fitness was actually predicting mortality better than some diseases. So in other words, people who had cardiovascular disease, type 2 diabetes, or smoked had the highest mortality risk, but guess who else did? People who did not smoke and did not have type 2 diabetes, hypertension, or any of these other diseases, but they had a low cardiorespiratory fitness. So in other words, not being physically active is a disease. It needs to be treated like a disease. It is a disease. We don't talk about it like a disease. We talk about it as optional. Well, no, it's a disease. Not being physically active is a disease.

So, how do you improve your cardiorespiratory fitness? Well, you might think aerobic exercise, that's the best way. Well, yeah, aerobic exercise is better at improving cardiorespiratory fitness than, for example, strength training is. But it turns out that vigorous-intensity exercise, particularly high-intensity interval training, pushes your cardiovascular system. During each interval, you push that cardiovascular system hard. You push your respiratory and muscular systems, recover, and then push them again, right? That seems to be the best way to improve cardiorespiratory fitness. And we know that because large studies have included participants that are actually meeting the physical activity guidelines for moderate intensity exercise. So they're doing about 2.5 hours a week of moderate intensity physical activity. So, depending on what journal you read, the definition of moderate intensity varies, but generally speaking, we're talking about people that sort of can have a breathy conversation, a little bit. They can talk, but they're breathy while exercising. That would be sort of moderate intensity exercise. About 40% of those individuals do not improve their VO2 max. That is almost a coin toss, and I want to make sure I improve mine. So, we know that those individuals can improve their VO2 max if they engage in vigorous intensity exercise. And so, we're going to talk about some of the best ways to improve cardiorespiratory fitness with these HIIT protocols.

So, pretty much all high-intensity interval training is going to improve your VO2 max. But it seems as though the longer the interval where you're pushing yourself, the more robust the improvement. And that's where the Norwegian 4x4 comes in. The Norwegian ski team has used this protocol. For four minutes, they go as hard as they can on a stationary bike and maintain that intensity for the entire four minutes. It is not an all-out effort. It's a hard effort, but you have to maintain it for four minutes. So, you have to pace yourself. It takes some trial and error to figure out what that intensity is going to be, but you'll figure it out after a couple of times. You do that for four minutes, recover for three minutes, and repeat the cycle four times. That's why it's the four by four. This is the most evidence-based way to really robustly improve cardiorespiratory fitness. If you haven't gone into a lab and had your VO2 max directly measured, I'm sure Andy Galpin measures it here at Parker. You can also estimate it. So, yeah, your wearable device provides a variation of the estimate. And I don't know whether it's accurate day to day, but it may be useful across longer periods. But you can do what's called the 12-minute run test and that's where you are running as fast as you can sustain for 12 minutes. You have to pace yourself and it has to be a flat track because the hills will make a difference in how fast you can go. You need a wearable device that can measure distance. Once you have the distance, you can use the formula. You can look it up. It's called the Cooper test. And you can find the formula and then that's a pretty good estimator of VO2 max.

Vigorous-intensity exercise, including the Norwegian 4x4, can reduce the aging of the heart. So as we age our hearts shrink and they get stiffer with age. A lot of the stiffness comes from glucose dysregulation, I guess. The longer glucose sits around in our vascular system, it forms something called advanced glycation end products. Those products stiffen collagen in the myocardium and pericardium surrounding the heart. That makes the heart stiffer with age. If you think about exercise, what happens? It really brings glucose into the muscles. So exercise is great for getting glucose in and really plays a role in improving the flexibility of our hearts. So Dr. Benjamin Levine conducted this study at UT Southwestern in Dallas. He's probably the world's leading expert on exercise physiology. He's an amazing researcher. He asked whether he could study middle-aged adults. So these were 50-year-olds who had no identifiable diseases other than the fact that they're sedentary. So they're not physically active, but they don't have type two diabetes or cardiovascular disease. They don't smoke or have those other risk factors. He wanted to see whether he could improve the structural changes associated with heart aging, right? And so he took these individuals and put them into two groups. There was the treatment group and then there was the control group. This was a two-year study. The treatment group received a demanding exercise training protocol. It was progressive. You can't just take someone that's not physically active and immediately have them do the Norwegian 4x4. It's going to be way too hard. Over 6 months, they progressed to the point where they could add more vigorous intensity exercise. After those six months and during the remaining year and a half, they exercised for about 5 hours a week. And that exercise included the Norwegian 4x4 once weekly and, at times, twice weekly. It also included a lot of moderate-to-vigorous exercise. This was about 75 percent of maximum heart rate. They were doing a lot of that type of cardiovascular training. They were also doing some resistance training as well. The control group did yoga-like stretching. Not that yoga isn't good for you. It just isn't going to reverse your aging heart as we're going to learn. So after those two years, the heart structure and size of those 50-year-olds showed an apparent reversal of about 20 years of cardiac aging. Their hearts resembled a 30-year-old's heart in size and stiffness after 2 years of this intense exercise training protocol. Very astonishing data. I love this study because it shows that it is never too late to make a big difference. The 50-year-olds were able to do this. If you put in that effort, a 20-year reduction in the structural aging of your heart is huge. It's huge and it's very motivating.