Q: What is exercise intensity?
A: In simplest terms, it's how hard an exercise is at a point in time. The technical definition is the level of momentary exertion during exercise.
Q: Why is it important?
A: Exercise of sufficient intensity is necessary to stimulate the body to make a change. When the body is worked beyond what it is equipped to handle, the body adapts as a form of self-protection. The body will make a positive adaptation only if given enough time to recover from the exercise. If you give yourself too much intensity -- if you try to lift weights every day or run a marathon every day -- you will get hurt.
Q: How hard should one exercise?
A: That depends on what you want to accomplish. The body will adapt to the nature of the demands placed on it. If one engages in lower intensity activities for extended periods of time, such as running, the body adapts by increasing endurance toward that activity with little or no increase in muscle strength. If one engages in higher intensity exercise, such as weight lifting, the body adapts by getting stronger but with less improvement in the way of endurance.
Q: If the goal is to get stronger, how much high-intensity exercise is necessary?
A: The higher the intensity, the less exercise you'll be able to withstand. That's a law. But this high-intensity exercise produces a bigger stimulus for strengthening. The larger stimulus for strength gains requires a longer recovery period. For the elite athlete, the required level of intensity will be quite high; for those who do little physical activity, the intensity level will be much lower and more manageable. Whether you're 18 or 80, there will be a level you can manage that will produce positive results. For example, try performing squats with adequate weight that you cannot possibly continue with good form after 2 minutes. Try doing it again next week with more weight or more repetitions. You'll find that most everybody will improve and, in fact, the improvement at first will come easily as your body is well rested.
Q: How much time is needed to recover from this high-intensity exercise?
A: If you start from the premise, which many people do, of how much exercise you can withstand, this leads to drudgery, insufficient recovery, lower intensity, less results and, eventually, quitting. Some spend several hours a week in a gym just to maintain their present level of strength or claim they have hit a plateau. It doesn't have to be that way. If they worked out a little less often, the intensity of their workouts would increase. They'd have more recovery time and they'd begin to see improvement again. If you start from the premise of how little intense exercise can you get away with and still achieve positive results, you will find you are willing to work out at a much higher level of intensity, have more time to recover, and have better results.
Q: So how often does one need to work out?
A: How often you need to work out will depend on a number of factors. The most important are level of intensity, duration of exercise and frequency of certain exercise. You can discover the right formula through trial and error. If you can find a trainer who knows how to manipulate these variables and, most importantly, knows how to do this safely, you find your continued improvement will be measured in years instead of months. With the right supervision, this is a strength-training program that people of any age or fitness level can stick to: a 30-minute workout, usually once a week, with continuing positive results.
Q: Do people get better results with this method than another?
A: Your body has limits on the amounts of stress it can recover from and genetic limits on improvements. The conventional method of more [repetitions], more sets and more time in the gym will allow you to reach your genetic potential; the high-intensity method will do the same. Both will involve pushing your body to its limits ... but the high-intensity method will involve more concentrated effort over a shorter time.
Q: So you think high-intensity is better for everyone than conventional programs?
A: I'm not going to say one is superior. Both produce results, but with one you spend less time in the gym.
Q: Overall, what are the greatest benefits?
A: With high-intensity exercise, you will have stronger muscles, stronger bones (less risk of osteoporosis), better balance, higher metabolism and less likelihood of injury. For older people, this is crucial.