Many people strive to be fit. Fitness, after all, is synonymous with health.
Having a high level of overall fitness is linked with a lower risk of chronic disease, as well as a better ability to manage health issues that do come up. Better fitness also promotes more functionality and mobility throughout one’s life span.
And in the short term, being active can help your day-to-day functioning, from better mood to sharper focus to better sleep.
Simply put: Our bodies are meant to move, and they tend to function better when we’re more fit.
That said, it’s also important to know that there are many different ways to be fit (think of a ballet dancer versus a bodybuilder or a sprinter versus a gymnast). And fitness does not have a singular “look.” In fact, appearance can’t necessarily tell you about someone’s habits, whether they’re actually physically active, or even whether they’re fit at all.
What It Means to Be Fit
According to the Physical Activity Guidelines for Americans set forth by the U.S. Department of Health and Human Services (HHS), there are five components of physical fitness:
- Cardiorespiratory Fitness Your VO2 max is a commonly used measure of this. It’s your body’s ability to uptake and utilize oxygen (which feeds all of your tissues), something that is directly related to your health and quality of life, says Abbie Smith-Ryan, PhD, professor and director of the Applied Physiology Laboratory at the University of North Carolina in Chapel Hill.
- Musculoskeletal Fitness This includes muscle strength, endurance, and power.
- Flexibility This is the range of motion of your joints.
- Balance This is your ability to stay on your feet and steady to avoid falls.
- Speed This is how quickly you can move.
A frequently cited peer-reviewed research paper from 1985 defined the difference between the terms “physical activity” (bodily movement resulting in energy expenditure), “exercise” (planned and structured physical activity), and “physical fitness.” The paper defined physical fitness as a set of attributes that people have or achieve that determines their ability to carry out daily tasks with vigor and alertness, without undue fatigue. Cardiorespiratory endurance, muscular endurance, muscular strength, body composition, and flexibility are components that can be used to measure fitness, also according to that paper.
In the real world, fitness translates to function, says Dr. Smith-Ryan. For example, can you carry your groceries or walk up the stairs without getting winded? Can you run around the backyard with your kids? Can you climb the stairs?
Exercise is distinct from fitness because exercise is what you do to improve your fitness.
Types of Fitness
There are a few main components of fitness, all of which are important for building a well-rounded exercise routine. Below, you will find the ones included in the Physical Activity Guidelines for Americans, which HHS highlights as the components that should be included in weekly exercise. (It’s worth noting that many definitions of fitness include other components as well, such as endurance, muscular endurance, power, speed, balance, and agility — as mentioned above.)
Aerobic (Cardiovascular) Exercise
Aerobic exercise is the foundation of every fitness program — and for good reason. Also called cardiovascular exercise or cardio, this type of physical activity increases your heart rate and breathing rate, which improves your cardiorespiratory fitness, according to the American Heart Association.
Aerobic exercise includes activities like brisk walking, running, cycling, swimming, aerobic fitness classes (like kickboxing), tennis, dancing, yard work, tennis, and jumping rope, per the Physical Activity Guidelines.
Strength Training
Strength training is an important way to improve mobility and overall functioning, particularly as you get older. “As you age, you lose muscle mass, which can have a significant impact on the quality of life. Strength exercises build bones and muscle, and more muscle protects your body from falls and the fractures that can happen in older age,” says Robert Sallis, MD, a family medicine doctor at Kaiser Permanente in Fontana, California, and chairman of the Exercise Is Medicine initiative with the American College of Sports Medicine (ACSM).
According to the ACSM, the definition of strength or resistance training is exercise that is “designed to improve muscular fitness by exercising a muscle or a muscle group against external resistance.” Activities that answer this call include lifting weights, using resistance bands or your body weight, carrying heavy loads, and even strenuous gardening, per the Physical Activity Guidelines from HHS.
Flexibility and Mobility
Flexibility and mobility are both important components of healthy movement, according to the International Sports Sciences Association. However, they are not synonymous.
Flexibility refers to the ability of tendons, muscles, and ligaments to stretch, while mobility refers to the body’s ability to take a joint through its full range-of-motion.
There is no specific recommendation for the number of minutes you should do activities that improve flexibility or mobility (such as stretching), and the health benefits of those activities are not known because of a lack of research on the topic, according to the Physical Activity Guidelines from HHS. But the guidelines note that flexibility exercises are important for physical fitness.
And the guidelines do recommend that older adults incorporate balance training into their weekly fitness routine. Evidence suggests that regular exercise that includes balance training can significantly reduce older adults’ risk of falls, which can cause serious and debilitating injuries, among other consequences.
Rest and Recovery
Building in rest and recovery days allows time for your body to repair the natural damage that occurs to muscles during exercise. Exercise, by definition, puts stress on the muscles and the body. The repairing or healing of that stress is how you get stronger (and fitter). But you need to give the body adequate rest after a workout for that recovery process to happen.
Recovery days can include no physical activity at all or they may look like an active recovery day, which means doing low-intensity, low-impact forms of exercise, such as walking or gentle yoga. Dr. Sallis generally recommends doing some activity every day, such as a 10-minute walk outdoors.
For rest and recovery days, the idea isn’t that you’re immobile on your couch; it’s just that you’re not pushing yourself to a point where physical activity feels strenuous or challenging.
