Every month in this article we talk about why it is important to exercise or we describe some kind of exercise that you might like to try. This month we will try to convert you once again to life that includes regular exercise by talking about VO2 max. Intrigued? Keep on reading because this may well be the article that gets you to put down the remote control.
Experts estimate that a sedentary person, because of muscle loss, a decreasing maximum heart rate and stiffening lungs and arteries, loses about 10% of his ability to do work every decade after his 35th birthday. What does this mean to you? One example that I've seen is that if you could run a mile in 6 minutes at age 35, then 30 years later if you do not exercise it would take you about 8 minutes. But what is worse is that what had been a simple run at 35 would become a lung-searing effort.
With exercise and smart training you can cut your loses dramatically. Here comes the importance of VO2 max, which is the maximum amount of oxygen a person uses while exercising at their limit for one minute. To find out yours, you will need to have a treadmill stress test and measure how much oxygen you are using with each breath as you exercise. If you are in shape, your muscles will use a lot of oxygen to create energy and you heart will be big and strong and able to push a lot of oxygen-rich blood into the muscles. You will therefore have a high VO2 max reading. If you are not fit, either your muscles will peter out or your heart will reach its maximum pace before much oxygen can be put out into use. You will get winded faster, and the moment of breathlessness will become sooner with each passing year.
Now, here is the first reason to begin and continue to exercise. It is that fit people don't have these problems. They lose VO2 max at a rate of only .5 percent or less a year. In one study of runners aged 50 to 82 who had continued training and intensity of exercise over a 16 year period, there was no change in VO2 max. The only reason some runners lose VO2 max is because their maximum heart rate decreases with age, something that we have no control over.
Women don't lose VO2 max at the same rate as men do. They typically have lower rates to begin with, but the difference between the sexes decreases as the years go by. If you keep exercising and training, what will be your time to run that mile at age 65? If it's true that you don't lose much before you're 50 and after that you decrease .5 percent annually, you should be able to make that mile in 6.27. Not too shabby. Having recently returned from watching our daughter run the New York Marathon, I can attest to the validity of this fact as I watched many older runners do their stuff with agility and speed.
Now lets look at what exercise helps within the body. First we'll examine how it helps your heart. As we shared before, if your VO2 max is high, it means your heart is strong, your lungs and arteries are accommodating and elastic, and that your muscles are lean and ready to burn oxygen to create energy. Can you raise your VO2 max? A sedentary man in his mid-30's can raise his VO2 max from 40-45 per kilogram of oxygen per minutes per kilogram of body weight to 50-55. The heart is a muscle and it responds to the stresses of exercise and training like any muscle. It gets stronger. When you exercise, the heart gets extra full from all the blood squeezed back into it by muscles contracting elsewhere in the body. The heart has to work harder to push this extra blood back out into the body and in this process the heart becomes stronger. When you are not exercising, your heart will beat slower and stronger fueling the body with fewer beats then it needed before you started to exercise. Let us give you an example of what we mean. At rest a typical couch potato's heart beats 70 times a minute, pushing out about 70 milliliters of blood per beat. After three months of endurance training, an average "ex couch potato's" resting heart rate may decrease to 55 beats per minute.
Second, lets look at how exercise can change muscles and bones. How does muscle respond to exercise? Although we are not sure what causes muscle soreness, whether it's caused by tiny tears or free radicals or maybe something we don't yet understand, what we do know is that after the muscle repairs itself it becomes more resilient to injury and learns to repair itself faster. Men begin to lose muscle after the age of 25 with a rate of decline of about 7 pounds per decade, if they don't do anything to halt the process. Both the size and number of muscle fibers decrease after the age of 30. You may not notice a loss of strength until after you are 40, but you'll lose about 5% of your strength every decade after that. What does this mean? A 25 year old man who weighs 170 pounds and has 89 pounds of muscle will lose 14 pounds of lean body mass by the time he is 45. His metabolic rate will decline accordingly, and if his caloric intake remains the same, his body fat will increase substantially. He may very well weigh the same after 20 years, but certainly will not look the same.
Women who do not exercise and do strength work lose about 5 pounds of muscle per decade before menopause and about a pound a year thereafter. You can head off much of this and even get stronger with regular upper and lower body strength training. For most of us this means using weights. You can also halt muscle mass loss by other activities including swimming, cross country skiing, aerobics and many of the other exercises we have spoken to you about in our exercise articles.
Working a muscle encourages the body to push more capillaries into the fibers of the muscle. This increases the flow of blood, oxygen and fuels the working muscle. You don't lose this ability as you age. Some studies show that fit older runners had the same number of capillaries in their running muscles as muscle in younger runners. An exercised muscle will also increase its number of mitochondria, the energy factories the muscles need to produce fuel for contractions. If the training stops, the number of mitochondria slowly disappear.
How about bones and flexibility? Although as we age our muscles shorten as elastic and collagen in our connective tissue becomes frayed and more dense, there is reason to believe that we can maintain our flexibility as we age. To prove this statement we will cite two things. First researchers have found that when teens and seniors were placed in the same stretch program, both groups had the same level of improvement in flexibility. The second fact concerns my most feared but favorite ballet teacher. As an adult I went back to class to keep in shape and took from an 80-something year old women who had been in the corps de ballet in the French Ballet. To get to her studio we traipsed up 4 flights of steps in her Embassy Row home in Washington. She put us through rigorous classes and when we complained, she would raise her leg straight up so that her knee met her nose. After class we would limp down those carpeted stairs holding onto the elegant railings until we reached the street level. That kind of flexibility may be part genetics but I can tell you I was over the rainbow the first time my muscles relearned how to raise and lower my leg onto the bar after years of doing other types of exercise.
Back to the important information. Bones react to stress the same way muscles do: they get stronger. Although exercise can't make them any denser than they are, they can slow decline that starts to affect women after the age of 35 and can lead to osteoporosis.
So now that we've convinced you of the merits of exercising, let us share the basics of how to do it. First, develop a plan for the year. If you want to be in a race or you want to do something specific like being able to walk in a hilly or mountainous region, you will want to get into shape. That means you will want to improve your endurance. Second, you will want to exercise more intensively a few days a week and slack off on other days, or do other types of exercise. That is remember to alternate, easy-hard. This gives your body a chance heal itself and to restore your energy. Third, make sure you vary what you do when you exercise. You can even vary the people with whom you exercise to make your exercise more social. Fourth, make exercise fun. Remember our article on exercising as family? Have you tried that yet? You can get a wonderful workout while forming family bonds. And lastly, our fifth suggestion is to keep a log. If you have record of your efforts you are less likely to skip a day, you'll know when you are getting bored with one type of exercise, you'll know when you are slacking off and best of all, you'll see how you are progressing toward your goal.
As a diabetic, the when to exercise is slightly different than for those who do not have to balance carbohydrate intake with expenditure of energy. We tend to exercise the same time each day so that we can control our blood glucose levels easier. It's easier to get one time right rather than learn how to control it at various times of the day. For me that's first thing in the morning after taking my blood glucose level and eating breakfast. Most of my friends have the convenience of rolling out of bed and into the exercise studio. They can wait to eat after class. This would be dangerous for those of us who need insulin. It is also important that we carry glucose tablets with us so that if exercise more than we expect, we don't have deal with hypoglycemia. What is important is that we do exercise. We need to be strong because we have to deal with a chronic disease that can and will cause long and short-term complications that will speed up cardiovascular diseases.
Well, have we convinced you about the benefits of exercise for your heart, lungs, vessels, muscles and flexibility? We sure do hope so. Go talk to your health care team about your long and short term goals. Get the OK to start a program and go for it. Make sure you also get guidelines from your health care team as when to not to exercise-i.e. when your blood sugar is too high. Come back next month when we will share some tests that will check your own level of fitness.
