Stacy Braff, MD
What is the difference between physical activity and physical fitness?
Physical activity refers to any movement produced by skeletal muscle which uses energy whereas physical fitness is measurable state such as strength or endurance. Exercise is planned physical activity with the goal of improving physical fitness and health. Physical fitness is broken into the five categories of cardiovascular endurance, muscular strength, muscular endurance, flexibility, and body composition. The Physical Activity Guidelines for Americans, 2nd Edition gives guidance on the amounts and types of physical activity needed to improve or maintain health and reduce chronic disease.
Why are physical fitness and physical activity important?
Many chronic medical diseases are influenced by physical activity and fitness and the lack of getting adequate aerobic activity is associated with about a 10 percent risk of premature mortality. Inadequate physical activity is contributing to about $117 billion in annual health care costs.
What are the benefits of physical activity?
There are many health benefits associated with regular physical activity including a lower risk of all-cause mortality, cardiovascular disease and death, hypertension, type 2 diabetes, and adverse lipid profiles. People who meet the physical activity guideline of approximately 150 minutes of moderate physical activity a week have an estimated 33% lower risk of all-cause mortality compared to those who are not physically active. However, benefits of reducing all-cause mortality, cardiovascular disease, and metabolic disease are seen with any amount of moderate-intensity physical activity.
Regular physical activity also reduces the risk of many cancers. It can help with weight loss when combined with a reduced calorie diet and help with the prevention of regain after initial weight loss. Neurological and emotional benefits include improved cognition and decreased risk of dementia, reduced anxiety, decreased risk of depression, and improved sleep, among other benefits.
How much physical activity is enough?
The Physical Activity Guidelines for Americans, 2nd edition breaks its recommendations up into Key Guideline categories based on age group and chronic health conditions. They guidelines include recommendations for aerobic physical activity, muscle -strengthening activity, and bone-strengthening activity.
The aerobic physical activity guidelines may be met by participating in either moderate-intensity or vigorous intensity activity. Adults should get at least 150 minutes (2 hours and 30 minutes) per week of moderate-intensity aerobic physical activity, or 75 minutes (1 hour and 15 minutes) of vigorous-intensity physical activity. In general, 2 minutes of moderate physical activity is equal to about 1 minute of vigorous. Additional health benefits are seen if able to go beyond these recommendations.
If unable to meet the recommended activity guidelines, adults should try to get as much moderate-intensity physical activity as they are able. It was previously believed that a minimum of 10 minutes of moderate to vigorous activity was necessary to contribute to the overall daily accumulation to benefit health, but more recent research has found that any amount contributes, even going up the stairs.
How do you measure moderate verses vigorous intensity?
The intensity of aerobic physical activity can be tracked as either absolute intensity or relative intensity. Absolute intensity is the amount of energy used during the activity, without considering a person’s fitness level, and is measured in METs. Moderate absolute intensity would range from 3.0 to 5.9 times the amount of energy expended at rest, or 3.0-5.9 METs. Vigorous absolute intensity is equivalent to 6.0 METs and above. Using absolute intensity in those with poor physical condition may be inaccurate. They may expend more energy performing physical activities due to their lack of fitness, and an activity of moderate intensity in a fit person may be vigorous in the unfit. In this case, using relative intensity may be more appropriate.
Relative intensity is based on the level of effort for a given activity and can be estimated with a Rated Perceived Exertion scale (e.g. Borg CR10 Scale, Modified RPE Scale). In a scale of 0 to 10, 0 would be equivalent of sitting and 10 would be maximum intensity. Moderate activity would be a 5 or 6 and vigorous-intensity activity would begin at 7 to 8. While performing a moderate-intensity activity a person should be able to able to hold a conversation but want to do only half the talking. During vigorous-intensity activity a person must take a breath with every few words.
How long does it take to see the benefits of physical activity?
Some benefits of physical activity may be seen immediately. Others may take days to weeks to manifest. A single bout of moderate-to-vigorous physical activity can improve blood pressure, insulin resistance, sleep, and anxiety on the day it is performed. The benefits of improved cardio-respiratory fitness, muscular strength, decreased depressive symptoms, and sustained reductions in blood pressure may require weeks or months of regular physical activity.
What is the relationship between physical activity, physical fitness and body weight?
Physical fitness and physical activity can lower the risk of all-cause mortality and cardiovascular mortality at any body weight. Studies have shown that all-cause mortality and cardiovascular mortality is lower in physically fit individuals with a high BMI compared to individuals with poor physical fitness and a normal BMI. Individuals with overweight or obesity can improve their health by becoming physically active independent of changes in their body weight.
Low levels of moderate-to-vigorous physical activity of about 75 minutes per week (half of the recommended adult guidelines) results in a 1.8 year gain in life expectancy and if individuals reach the recommended levels of physical activity, there is a 3.4 year gain in life expectancy at every level of BMI. A lack of physical activity and a high BMI (35.0-39.9) was associated with 7.2 years of life lost when compared with meeting physical activity guidelines and being normal weight.
Exercise, a component of physical activity, can help promote weight loss if done along with caloric restriction. However, the amount of weight loss seen in individuals who do not restrict calories may vary significantly from person to person, from 0 to 2 kg loss. In order to lose any significant weight from physical activity without dietary change, one would have to increase their activity levels well beyond the current physical activity guidelines.
For more helpful information on physical activity, view our resources below!
U.S. Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd edition. Washington, DC: U.S. Department of Health and Human Services; 2018.
“The Role of Exercise and Physical Activity in Weight Loss and Maintenance”, Damon L. Swift, Ph.D, Neil M. Johannsen, Ph.D.3,5, Carl J. Lavie, M.D.3,6, Conrad P. Earnest, Ph.D.4, and Timothy S. Church, M.D., M.P.H., Ph.D. Prog Cardiovasc Dis. 2014 ; 56(4): 441–447. doi: 10.1016/j.pcad.2013.09.012.
“Effects of physical inactivity and obesity on morbidity and mortality: current evidence and research issues.” Blair SN1, Brodney S. Med Sci Sports Exerc. 1999 Nov;31(11 Suppl): S646-62.← Antihistamines and Weight Gain