The 5 Components of Fitness: What You Need to Know

When it comes to overall health, physical fitness plays a significant role. In fact, the Centers for Disease Control and Prevention (CDC) links regular physical activity to reduced risk of cardiovascular disease, type II diabetes, some cancers, improved bone health, enhanced mental health, and improved quality of life with age. And those are just a few of the benefits. Research published in a 2014 issue of Interface Focus found that physical fitness improved mental and physical resilience, as well as cognition, while another 2014 study published in Sports Medicine found that muscular fitness in children was associated with improved self-esteem, bone health, and reduced risk of cardiovascular disease and metabolic risk factors.

Exercise really does a body good.

Of course, most people understand that there are benefits that arise from prioritizing physical fitness. The trick is understanding what, exactly, "fitness" is, and how a person can go about getting fit. That's where the five components of fitness come in. These five components—cardiovascular endurance, muscular strength, muscular endurance, flexibility, and body composition—are the blueprint for the American College of Sports Medicine's (ACSM's) physical activity guidelines, and they provide a helpful tool for organizing and executing your own well-balanced workout routine.

1
Cardiovascular Endurance

Cardiovascular Endurance
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Cardiovascular endurance (also known as cardiorespiratory endurance or aerobic fitness) refers to your body's ability to efficiently and effectively intake oxygen and deliver it to your body's tissues by way of the heart, lungs, arteries, vessels, and veins. By engaging in regular exercise that challenges your heart and lungs, you can maintain or even improve the efficient delivery and uptake of oxygen to your body's systems, enhancing cellular metabolism and easing the physical challenges of everyday life.

Given that heart disease accounts for roughly 630,000 deaths in the United States each year, starting a workout program that enhances cardiovascular fitness is of particular importance. Running, walking, cycling, swimming, dancing, circuit training, and boxing are just a few of the many workouts designed to benefit heart health.

The key, of course, is consistency. The ACSM's physical activity guidelines call for at least 150 minutes of moderate-intensity exercise each week, or 75 minutes of vigorous exercise.  It may sound like a lot, but that breaks down to just 15 to 30 minutes of exercise per day, five days a week, depending on how hard you push yourself.

2
Muscular Endurance

Muscular Endurance
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Muscular endurance is one of two factors that contribute to overall muscular health. Think of muscular endurance as a particular muscle group's ability to continuously contract against a given resistance. Long-distance cyclists offer a clear example. To continuously pedal a bike over a long distance, often up steep inclines, cyclists have to develop fatigue-resistant muscles in their legs and glutes. These fatigue-resistant muscles are evidence of a high level of muscular endurance.

Likewise, holding a plank to develop core strength is another example of muscular endurance. The longer you're able to contract your abdominals and hold your body in a steady position, the greater endurance you have through your hips, abdominals, and shoulders.

It's important to realize, though, that muscular endurance is muscle group-specific. This means you can develop high levels of endurance in some muscle groups (like cyclists building endurance in their legs) without necessarily developing the same level of endurance in other muscle groups. Likewise, the extent to which you choose to focus on muscular endurance should be directly related to your own health or fitness goals.

For instance, for health reasons, you may want to develop enough endurance to simply climb up several flights of stairs or to lift and carry groceries from your car to your house. But if you want to become an endurance athlete, capable of competing in sports that require continual muscle contraction, such as obstacle course races, CrossFit, or cycling, you may want to place a higher focus on training regimens that use high-repetition strength training and sport-specific activity to make you a better athlete.

3
Muscular Strength

Muscular Strength
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While muscular endurance refers to how fatigue-resistant a particular muscle group is, muscular strength refers to the amount of force a particular muscle group can produce in one, all-out effort. In strength training terms, it's your one-rep max.

Like muscular endurance, muscular strength is muscle group-specific. In other words, you may have incredibly strong glutes, but comparatively weak deltoids. Or incredibly strong pectoral muscles, but comparatively weak hamstrings. This is why a well-balanced strength training program that targets all of your major muscle groups is so important.

The extent to which you train for strength is, again, determined by your own health and fitness goals. For instance, if your focus is on health, you know you should be strong enough to lift a heavy box or to easily stand up from a chair. In this circumstance, enhanced muscular strength may be a byproduct of a workout routine focused more on developing muscular endurance.

If, however, you want to develop muscle mass or to be able to lift heavier weights at the gym, your training regimen should be focused more on lifting heavy weights.

It's possible to improve muscular strength and endurance at the same time, but selecting a set and rep scheme to suit your goals is important. Generally speaking, if your goal is to get stronger, you need to lift heavier weights, taking your muscles to fatigue with each set. Usually, this means performing sets with fewer total repetitions. If, however, your goal is to improve muscular endurance, lighter weight and higher reps are typically the most efficient route.

Either way, the ACSM's guidelines state that adults should perform strength training exercises two to three days a week using a variety of exercises and equipment to target all the major muscle groups. This can be done in conjunction with, or independent of, cardiovascular training. For instance, circuit training routines that combine strength exercises and cardio into a single bout of training can make your exercise program more efficient.

4
Flexibility

Flexibility
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Flexibility refers to the range of motion you have around a given joint. Like muscular strength and endurance, flexibility is joint-specific. For instance, you may have very flexible shoulders, but tight and inflexible hamstrings or hips.

Flexibility is important at any age—it plays a role in unhindered movement and can affect your balance, coordination, and agility. Maintaining a full range of motion through your major joints can reduce the likelihood of injury and enhance athletic performance.

And as you age, the importance of flexibility becomes even more clear. Think of individuals who are elderly—they often walk with a shuffle, or have a hard time reaching their arms over their heads. This may affect their quality of life, making it more challenging to perform activities of daily living, such as reaching items on high shelves, picking up items off the floor, or simply moving effectively to catch their balance if they start to fall.

While completely stopping the aging process isn't possible, protecting your joints and maintaining mobility can help keep you spry well into your Golden Years. The ACSM's physical activity guidelines call for adults to engage in flexibility exercises at least two or three days each week. You can do this through static stretching, where you hold a stretch for 10-30 seconds at a time, or through workouts that take you through dynamic stretching exercises, such as barre, yoga, Tai Chi, or Pilates.

5
Body Composition

Body composition, or your body's ratio of fat mass to fat-free mass, is the final component of health-related physical fitness. Because high levels of fat mass are associated with negative health outcomes, such as heart disease and type II diabetes, attaining and maintaining a healthy body composition is a goal of just about all regular exercise routines.

The good news is, improved body composition is often an outcome of working on and improving the other four components of fitness. If you're regularly hitting the gym, doing cardio, strength training, and working on flexibility, chances are you're developing muscle mass (some of that fat-free mass) while reducing fat mass. The combined effect is an improved fat- to fat-free mass ratio, and enhanced body composition.

Of course, to see improvements in body composition, you need to know what your starting point is. Weighing yourself on a scale won't do the trick, as weight alone tells you nothing about the makeup of your internal tissues. Instead, talk to a trainer about having your body fat percentage tested, or consider purchasing a scale that uses bioelectrical impedance analysis (BIA) to estimate body fat percentage. The results are just estimates that typically fall within three to four percentage points of your actual body fat percentage, so it's important not to get too hung up on the specific numbers. That said, you can use them as a barometer to monitor changes and make sure you're seeing improvements over time.

Sources:

Centers for Disease Control and Prevention. "Heart Disease Fact Sheet." https://www.cdc.gov/dhdsp/data_statistics/fact_sheets/fs_heart_disease.htm. 2017.

Centers for Disease Control and Prevention. Healthy Places: Physical Activity. https://www.cdc.gov/healthyplaces/healthtopics/physactivity.htm. 2017.

Silverman M, Deuster P. "Biological mechanisms underlying the role of physical fitness in health and resilience." Interface Focus. https://doi.org/10.1098/rsfs.2014.0040. August 2014.

Smith JJ, Eather N, Morgan PJ, Plotnikoff RC, Faigenbaum AD, Lubans DR. "The Health Benefits of Muscular Fitness for Children and Adolescents: A Systematic Review and Meta-Analysis." Sports Medicine. https://doi.org/10.1007/s40279-014-0196-4. September 2014.

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