Workout to Improve Health
Mankind evolved over millions of years to survive by walking or running to chase prey or gather food. It was often difficult to digest and was scarce. And yet in the space of a mere few hundred years we have become the masters of our environment, and food has become plentiful. In the modern world we are surrounded by machines and gadgets that allow us to avoid almost all physical effort. The food we can buy often contains large amounts of sugar and fat. Boredom, which might otherwise have motivated us to become active, is satisfied by television and video games and other sedentary activities.
But in the western world over-eating and lack of exercise is having a catastrophic effect on health. Not only do we put on weight, but our cardiovascular systems, evolved for regular use, lose their potency. Like any machinery left unused, the components begin to rust and seize up. The risk is that when they are needed they fail suddenly and catastrophically. We become vulnerable to heart disease, cardiovascular disease, and type 2 diabetes. As our bodies lose their shape we lose self-esteem, exercise becomes more difficult, and we may be drawn into a downward spiral of poor health.
It can be difficult to begin exercise after a period of inactivity, or a lifetime. It is not just the muscles that need to develop. The entire metabolism adjusts with physical training, and you have to expect that initially it will be in a negative direction. The immediate effects of training are a decrease in fitness level, followed by a recovery period during which the original fitness level returns. Only then does the benefit of the training begin as the body anticipates the increased fitness demands. The recovery period is often quoted as being of the order of 24-48 hours. It can be manifest as muscle discomfort, although there are many components of physical fitness and they all have different recovery cycles.
The recommended cycle is to resume exercise at the end of the recovery period, hence the guideline of exercising at intervals three times a week as an optimum. Before vigorous exercise it is worth warming up so that the heart rate and breathing increase gradually in preparation for exercise. The benefit of stretching before exercise is disputed and may actually be harmful, but it is widely recommended that stretching afterwards will reduce muscle soreness later. This soreness often comes on 24 hours after unusually strenuous exercise (for example a race or a new activity), and can be so severe as to make normal walking and mobility difficult and uncomfortable.
Once a higher level of fitness is achieved, continuing exercise is required to maintain it. If exercise is stopped, either through injury or change of lifestyle, then the fitness level will eventually return to the original level. This happens surprisingly quickly, of the order of mere weeks, before exercise and achieving fitness becomes an effort again.
The intensity of exercise is measured as a percentage of maximum heart rate (MHR), which really means the maximum safe heart rate. The MHR varies with age and as a rule of thumb it is 220 minus your age for an adult (where MHR is measured in beats per minute). The intensity of exercise can be categorised as low (up to 70% of MHR), medium (70-80% MHR) or high (80-90% MHR).
Low intensity exercise improves fitness and can be maintained for a long period. Because a relatively small amount of energy is consumed over a long time, the metabolism has time to convert fat into energy. It is estimated that at these levels about 50% of the required energy comes from fat and 50% from carbohydrate. This means that it is the recommended type of exercise if the goal is to lose weight, because at higher intensities most of the energy is derived from carbohydrate.
Medium intensity exercise is the band up to the anaerobic threshold (AT). As far as the cardiovascular system is concerned, aerobic exercise can be continued indefinitely. Regular exercise at this level will improve the cardiovascular system so that the AT will gradually be increased, and is often used in endurance sports such as distance running.
High intensity exercise is above the anaerobic threshold and is beginning to put pressure on the heart. As a result the strength of the heart muscle will increase, and different types of muscle fibres will develop. Above the AT the body is unable to get enough oxygen through the cardiovascular system to the muscles for aerobic metabolism, and the anaerobic metabolism is used to bridge the gap. This level of exercise tends to be used in non-endurance sports, for example running sprint distances.
As the intensity increases still further, towards 100% MHR, the metabolism begins to work entirely anaerobically. The build-up of lactic acid in the muscles becomes painful and can only be maintained for a limited period; from seconds to a maximum of about two minutes. Following exercise at this level it may take some minutes for the body to pay off the oxygen debt before exercise can resume.
The higher the intensity, the more calories will be consumed. In terms of balancing the overall calorie budget for a given rate of calorie intake, the more intense and the longer the exercise the better. But if the objective is to lose fat tissue, then a low or medium intensity level of exercise over a long period is more effective. It is also dangerous to suddenly increase the level of exercise or engage in intense exercise without first acquiring the appropriate level of fitness.
But in the western world over-eating and lack of exercise is having a catastrophic effect on health. Not only do we put on weight, but our cardiovascular systems, evolved for regular use, lose their potency. Like any machinery left unused, the components begin to rust and seize up. The risk is that when they are needed they fail suddenly and catastrophically. We become vulnerable to heart disease, cardiovascular disease, and type 2 diabetes. As our bodies lose their shape we lose self-esteem, exercise becomes more difficult, and we may be drawn into a downward spiral of poor health.
It can be difficult to begin exercise after a period of inactivity, or a lifetime. It is not just the muscles that need to develop. The entire metabolism adjusts with physical training, and you have to expect that initially it will be in a negative direction. The immediate effects of training are a decrease in fitness level, followed by a recovery period during which the original fitness level returns. Only then does the benefit of the training begin as the body anticipates the increased fitness demands. The recovery period is often quoted as being of the order of 24-48 hours. It can be manifest as muscle discomfort, although there are many components of physical fitness and they all have different recovery cycles.
The recommended cycle is to resume exercise at the end of the recovery period, hence the guideline of exercising at intervals three times a week as an optimum. Before vigorous exercise it is worth warming up so that the heart rate and breathing increase gradually in preparation for exercise. The benefit of stretching before exercise is disputed and may actually be harmful, but it is widely recommended that stretching afterwards will reduce muscle soreness later. This soreness often comes on 24 hours after unusually strenuous exercise (for example a race or a new activity), and can be so severe as to make normal walking and mobility difficult and uncomfortable.
Once a higher level of fitness is achieved, continuing exercise is required to maintain it. If exercise is stopped, either through injury or change of lifestyle, then the fitness level will eventually return to the original level. This happens surprisingly quickly, of the order of mere weeks, before exercise and achieving fitness becomes an effort again.
The intensity of exercise is measured as a percentage of maximum heart rate (MHR), which really means the maximum safe heart rate. The MHR varies with age and as a rule of thumb it is 220 minus your age for an adult (where MHR is measured in beats per minute). The intensity of exercise can be categorised as low (up to 70% of MHR), medium (70-80% MHR) or high (80-90% MHR).
Low intensity exercise improves fitness and can be maintained for a long period. Because a relatively small amount of energy is consumed over a long time, the metabolism has time to convert fat into energy. It is estimated that at these levels about 50% of the required energy comes from fat and 50% from carbohydrate. This means that it is the recommended type of exercise if the goal is to lose weight, because at higher intensities most of the energy is derived from carbohydrate.
Medium intensity exercise is the band up to the anaerobic threshold (AT). As far as the cardiovascular system is concerned, aerobic exercise can be continued indefinitely. Regular exercise at this level will improve the cardiovascular system so that the AT will gradually be increased, and is often used in endurance sports such as distance running.
High intensity exercise is above the anaerobic threshold and is beginning to put pressure on the heart. As a result the strength of the heart muscle will increase, and different types of muscle fibres will develop. Above the AT the body is unable to get enough oxygen through the cardiovascular system to the muscles for aerobic metabolism, and the anaerobic metabolism is used to bridge the gap. This level of exercise tends to be used in non-endurance sports, for example running sprint distances.
As the intensity increases still further, towards 100% MHR, the metabolism begins to work entirely anaerobically. The build-up of lactic acid in the muscles becomes painful and can only be maintained for a limited period; from seconds to a maximum of about two minutes. Following exercise at this level it may take some minutes for the body to pay off the oxygen debt before exercise can resume.
The higher the intensity, the more calories will be consumed. In terms of balancing the overall calorie budget for a given rate of calorie intake, the more intense and the longer the exercise the better. But if the objective is to lose fat tissue, then a low or medium intensity level of exercise over a long period is more effective. It is also dangerous to suddenly increase the level of exercise or engage in intense exercise without first acquiring the appropriate level of fitness.
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