A NEW STUDY SHEDS LIGHT ON THE PHYSIOLOGICAL RESPONSE TO EXERCISE. Physical activity is an important tool for maintaining or restoring good health. The new research provides insights into the molecular mechanisms underlying exercise-related health improvements. We’ll look at the basic science of how obesity and exercise affect muscle and fat. We’ll examine how exercise works its magic at a single-cell level.
Get regular physical activity, and you can reduce your risk of becoming obese, developing diabetes, suffering from cardiovascular disease, dodge particular cancers, and more. But how does exercise work its physiological magic?
First, we’ll review some of the health benefits of regular physical activity. Second, we’ll turn to a new study that sheds light on how moving affects our physiology at a basic level.
Physical activity and cardiovascular disease
Many of us lead sedentary lifestyles, at least in the United States. Unfortunately, not getting regular physical activity is an independent risk factor for the early development of coronary heart disease.
Unfortunately, much of the evidence supporting the risk-reducing properties of exercise comes from long-term observational studies that demonstrate this:
Those who get regular physical activity have much less coronary heart disease and a lower risk of experiencing cardiac arrest.
Let’s compare the least active among us with the most active. I live in King County, Washington (USA). There, researchers from the University of Washington performed a population-based case-control study to examine the associations between regular high-intensity and moderate-intensity leisure-time physical activity and primary cardiac arrest.
The investigators looked at 333 patients with primary cardiac arrest, aged 25 to 75, attended by paramedics. Controls were randomly selected from the same community and matched for age and sex. None of the subjects had a history of heart disease, major health problems, or self-reported poor health.
The researchers interviewed partners of patients and controls to assess participation in 15 high-intensity and six moderate-intensity physical activities during the previous year.
Here are the relative risk reductions by activity type:
- Gardening for more than 60 minutes per week appeared to be associated with a drop in risk by two-thirds.
- Walking for exercise for more than 60 minutes per week appeared to be associated with a nearly three-quarters risk reduction.
- Engaging in high-intensity activities appeared to be associated with a drop in risk by two-thirds.
Unfortunately, I did not see absolute risk reduction numbers. However, here is some context: Globally, cardiac arrest takes more lives than colorectal cancer, breast cancer, prostate cancer, influenza, pneumonia, auto accidents, HIV, firearms, and house fires combined. In one year alone, 350,000 Americans die from cardiac arrest.
A sedentary lifestyle is an independent risk factor for cardiac arrest. Of course, exercise is not completely free of potential perils. Physical activity can have rare adverse effects, including heart attack, heart rhythm problems, sudden death, and rhabdomyolysis.
Rhabdo happens when damaged muscle tissue releases its proteins and electrolytes into the blood. These substances can damage the kidneys and heart and lead to permanent disability or even death.
Physical activity and weight
Exercise is important to prevent obesity; sedentary behavior leads to weight gain. For older or obese adults, higher activity levels (compared to young adults) appear necessary to prevent weight gain.
A study of 34,000 females (with an average age of 54) consuming a usual diet had an average weight gain of 2.6 kilograms (5.7 pounds) over 13 years.
Compared with females doing more than 420 minutes per week of exercise (an average of one hour daily), those engaging in less activity gained significantly more weight.
Physical activity appeared inversely related to weight gain only among normal-weight individuals. To maintain normal body weight in mid-life, the females in the study needed higher levels of physical activity (about 60 minutes daily).
Once overweight, physical activity alone (without controlling caloric intake) did not prevent weight gain.
The available research findings suggest that physical activity protects against obesity regardless of an individual’s genetic predisposition to it.
Physical activity and life expectancy
Physical inactivity is associated with a reduced life expectancy. A retrospective study published in JAMA addresses this issue. The study explores the link between long-term mortality and various levels of cardiorespiratory fitness.
Cardiorespiratory fitness measures how well your heart and lungs pump blood and oxygen during prolonged exercise. The more fit you are, the higher your cardiorespiratory fitness.
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