Exercise isn't a new idea. Records of people exercising go back to 1100 B.C., when the Greeks competed in the javelin throw, distance running, archery, and boxing. Hippocrates (460 B.C.-377 B.C.), the father of medicine, wrote that "eating alone will not keep a man well; he must also take exercise." Milo of Croton, in 6 B.C., discovered the Principle of Progressive Overload, in which he carried a calf every day on his shoulders and as it grew into a bull and got heavier, he got stronger (just like adding heavier dumbbells).
Skip ahead a thousand years to 1844, when the YMCA was founded and people started to do more formal exercise. Then, in 1896, the first modern Olympic games began, and by the early 1900s, gymnastics was mandatory for all American school children. In the late 1950s, things really picked up; Jack LaLanne had an exercise show on TV; the President's Council on Physical Fitness was created; in the 1960s and '70s, Jackie Sorensen and Jane Fonda exercise videos, Nautilus, Inc. (maker of fitness equipment), was founded in the 1980s; Ken Cooper coined the word "aerobics," and a running phenomenon was started by George Sheehan, Jim Fixx, and others. Today, we have limitless types of exercise classes, technology built into every cardio machine, and all sorts of contraptions for building muscles. In this article, we'll take a more in-depth look at what exercise is all about.
Physical fitness is a measure of the condition of the body to perform during activities of daily living (light, moderate, and strenuous), formal exercise (like when you work out), and emergencies (as when you must escape from danger like a fire). The physical fitness of our nation is declining, proved by the rising rates of obesity, diabetes, some types of cardiovascular disease, and other medical conditions. To improve physical fitness, one must "practice," or work out. Emphasis should be on improving aerobic conditioning (stamina or endurance), muscular strength and endurance, and flexibility. The types of exercise necessary to do this are described next.
Types, or modalities, of exercise fall into three major groups: aerobic, anaerobic, and flexibility. Here's a description of each.
Aerobic means "with oxygen." Aerobic exercise is performed at an intensity that causes you to feel "warm and slightly out of breath." Examples are swimming, dancing, jogging, brisk walking, rowing, and all the cardio machines in your gym. These can be done anaerobically as well by increasing the intensity (see more about anaerobic exercise below).
Aerobic exercise burns more fat than anaerobic exercise. That's because fat has more calories per gram than carbohydrate (9 vs. 4) and because it's so dense it needs more oxygen to burn it for fuel in the muscle. In order to get more oxygen to burn fat, you need to exercise moderately so there is time to bring in large volumes of oxygen. If you sprint or lift weights in short bursts, there's no time to bring in lots of oxygen, so the primary fuel is carbohydrate.
Anaerobic exercise is working out at an intensity that gets you out of breath and sweaty. Typically, it's performed in brief spurts like a set of lifting weights or a sprint. Games like basketball or soccer have large components of anaerobic exercise because of the sprinting, but a long-endurance event might too when you hit the hills or sprint at the finish line.
There are no specific guidelines as to how much to stretch. It feels good, and so I recommend stretching as often as you like. Most people tend to sit most of the day, and so I recommend getting up every so often and taking a good stretch. I guarantee you'll feel better. Stretch your neck, or maybe do some side bends, or even bend forward and touch your toes. Whatever it is, listen to your body and stretch until you feel better.
Proper technique for stretching is to push into the stretch until you feel mild tension, hold until you feel looser, then push a little more. The key point is to hold until you feel looser. So, listen to your body and stretch until you feel looser.
Stretch and tone classes are popular for a reason. They feel good and you get results. Yoga is another great way to stretch, plus, it's meditative and stress reducing. Start with a beginner class if you're new at it. Your muscles will know after your first session that you did something.
When your body feels limber, you feel more connected to it. Muscles communicate with the pleasure and sensation centers in your brain. When muscles feel relaxed, you feel that way, too. There's a limited amount of research to prove this, but ask 100 people who stretch if it's true, and they will tell you it is. Does stretching prevent injury? There's very little research to prove it. I recommend calf stretching to treat conditions like plantar fasciitis (pain in the heel), and gentle stretches for rehabilitation after muscle pulls and strains but only after it starts healing. As for prevention, there's no downside to keeping muscles loose, and it feels good, so why not? And if it does happen to prevent injury, then it's a bonus.
The very best way to stretch, particularly if you're doing cardio and working your legs, is to warm up for five to 10 minutes to get the muscles filled with blood and warm. Then stop your cardio and stretch. You'll notice the difference compared with a cold stretch right away. When I coached fencers, I always had them start practice with a 1-2 mile jog and then stretch. Fencers need lots of flexibility, and I didn't want any of my athletes pulling muscles. An excellent resource for flexibility exercises is Bob Anderson's book or DVD titled Stretching.
At rest, you burn just about equal amounts of carbohydrate and fat. If you were to get up and move quickly and get slightly breathless, then the percentage of fat burned would drop because it takes more oxygen to burn a gram of fat than carbs since fat has more calories than carbs (9 per gram compared with 4 per gram for carbs). At lower intensities of aerobic exercise, you burn more fat than carbohydrate. At higher intensities of anaerobic exercise, you burn more carbs since you're more breathless and can't deliver enough oxygen to the muscles to burn more fat (carbs are fast-acting fuel). However, don't get misled into thinking burning more fat means burning more calories. For example, if you jog for 30 minutes at 6 mph (3 miles) and you weigh 150 pounds, you'll burn 300 calories. But if you run at 8 mph for 30 minutes (4 miles) you'll burn 400 calories. You may burn a higher percentage of fat at the slower speed, but you burn fewer total calories. And if you're looking for weight loss, you're looking to burn the most calories you can. Plus, at the higher speed, you get fitter. You know the cardio and fat burning settings on the treadmill? Forget about it. Don't go at the slower fat-burning speed if you want to burn more calories and get more fit. The fat burning will happen at either intensity. Get more fit.