Research has confirmed that human beings are born to move. A need for exercise is embedded in our genetic structure. When that requirement is ignored, metabolic diseases gradually ensue, including the symptoms that are the precursors of diabetes and heart disease, as well as heart disease itself. Our ancestors engaged in regular low-level exercise as a necessary part of their existence. These days it’s easier to avoid even minimal exercise.
The body responds to exercise by upregulating various processes related to energy production and muscle activity. Conversely, that which is not used is lost. That applies to all body structures, from head to toe. One study found that after several hours of total inactivity, changes in gene expression occurred in more than 100 genes. A more recent study examined the effects of exercise on a particular enzyme, lipoprotein lipase.1 LPL exists in fat and muscle. In fat cells it’s involved in the synthesis of fat. In muscle it increases the level of intramuscular triglycerides, which are an important fuel source for exercise. It also has other functions that protect your health.
LPL plays a pivotal metabolic role in the way the body handles various types of circulating lipids, such as triglycerides and cholesterol. The effect is so potent that a reduction in the activity of LPL leads to a fivefold increase in the odds of acquiring cardiovascular disease. You can view LPL as a kind of fat conductor, determining where and how the body will use various fats. Without the presence of LPL, all hell breaks loose in fat metabolism, resulting in disease.
Without LPL, plasma triglyceride circulating in the blood isn’t properly taken up by tissues. The fat then circulates back to the liver, where it’s used to make cholesterol and other lipids, and that makes demands on the body that eventually lead to cardiovascular disease, the number-one killer. The biggest question among exercise scientists is how much exercise people need for optimal health. In a recent book about preventing cardiovascular disease, cardiologist Robert Superko suggests that you engage in vigorous endurance exercise every day for at least one hour to derive maximal cardiovascular benefits. But in a new study that looked at the effects of exercise on LPL activity, the authors found that easy treadmill walking by the subjects, which were rats, increased LPL activity a whopping eightfold over inactive levels, and it happened rapidly.
The benefits, however, are transient. For best results you must engage in some type of aerobic activity nearly every day, as the enzymes and genes involved in exercise-induced health protection are acutely related to activity level. When the activity ceases, the genes turn off like a light; it happens that fast. You may not have to kill yourself with high-intensity aerobics, but you do have to be aerobically active several days a week for maximum health benefits.
1 Bey, L., et al. (2003). Suppression of skeletal muscle lipoprotein lipase activity during physical inactivity: a molecular reason to maintain daily low-intensity activity. J Physiol. 551:673-82.