Essential Elements and Benefits of Physical Fitness

Becoming and staying physically fit is an important part of achieving optimal health. A well-rounded exercise program can improve your health in a number of ways. It keeps the heart and lungs strong, strengthens muscles and bones, helps to protect against chronic disease, improves brain and mental health, and can support healthy body weight. There are four main components of physical fitness as it relates to health and function: cardiorespiratory fitness, musculoskeletal fitness, flexibility, and balance. 1 Each component offers specific health benefits, but optimal health requires some degree of balance between all four. (Speed, or the ability to move the body quickly, is also considered a component of physical fitness, but it is less related to health and more relevant to competitive athletes.1)

Some forms of exercise can help build multiple types of fitness. For example, riding a bicycle not only builds cardiorespiratory endurance; it can also improve muscle strength and endurance. Some forms of yoga and Pilates can also build muscle strength and endurance, along with flexibility and balance. However, building fitness in all four categories generally requires incorporating a range of activities into your regular routine. As you increase physical activity, you will notice that you are able to continue your activity longer and with greater ease.

The Essential Elements of Physical Fitness

Cardiorespiratory Fitness

Cardiorespiratory fitness is defined as “the ability to perform large-muscle, whole-body exercise at moderate-to-vigorous intensities for extended periods of time,” according to the Physical Activity Guidelines for Americans.1 Cardiorespiratory fitness is built by aerobic activity, during which you move your body’s large muscle groups in a continuous and rhythmic way, and your heart and breathing rate increase. Examples of aerobic activities include walking, running, swimming, jumping rope, and riding a bike.

A path where people are walking, biking, and jogging through the trees.

Aerobic physical activity can range in level of intensity; for example, brisk walking is considered moderate intensity, and running or jogging is considered vigorous intensity. As intensity increases, so do heart and breathing rates to meet increased demand for oxygen in working muscles. Regular, moderate aerobic activity—about thirty minutes at a time on five days per week—trains the body to deliver oxygen more efficiently, which strengthens the heart and lungs and reduces the risk of cardiovascular disease. Strengthening your heart muscle and increasing the blood volume pumped in each heartbeat boosts your ability to supply your body’s cells with oxygen and nutrients and remove carbon dioxide and metabolic wastes. It also leads to a lower resting heart rate for healthy individuals. Aerobic physical activity can also help maintain a healthy weight.1

Many aerobic activities also count as bone-strengthening activity, which promotes bone growth and strength by producing a force on the body’s bones. Weight-bearing activities like running, walking, and doing jumping jacks are considered bone-strengthening, whereas activities like swimming and biking that put less force on the body’s bones are not. Bone-strengthening activities are especially important during childhood and adolescence, when they promote greater bone mass and strength and improved bone structure. In older adults, participating in aerobic and bone-strengthening activities slows the decline in bone density that often occurs with aging.

Musculoskeletal Fitness

Musculoskeletal fitness is defined as “the integrated function of muscle strength, muscle endurance, and muscle power to enable performance.”1 Musculoskeletal fitness is developed and maintained by weight or resistance training, often called anaerobic exercise. Anaerobic exercise consists of short duration, high intensity movements that rely on immediately available energy sources and require little or no oxygen during the activity. This type of training includes lifting weights, working with resistance bands, using body weight (such as for push-ups and pull-ups), and doing work such as carrying heavy loads or vigorous yard work. Building musculoskeletal fitness is not just for athletes and bodybuilders—it’s important for children, older adults, and everyone in between. The support that your muscles provide allows you to work, play, and live more efficiently.

A man in a gym sitting on a bench with dumbbells in his hands.

Muscle-strengthening activity often involves the use of resistance machines, resistance bands, free weights, or other tools. However, you do not need to pay for a gym membership or expensive equipment to strengthen your muscles. Homemade weights, such as plastic bottles filled with sand, can work just as well. You can also use your own body weight and do push-ups, leg squats, abdominal crunches, planks, and other exercises to build your muscles. What is important is that your training incorporates exercises that together will work all the major muscle groups of the body, including the legs, hips, chest, back, shoulders, arms, and abdomen. To improve muscle strength, do one to three sets of 8 to 12 repetitions per exercise, with enough weight that it is difficult to do another repetition at the end of a set.

If strength training is performed at least twice per week, it can help improve muscular fitness and bone health, as well as manage health conditions like diabetes, arthritis, hypertension, and many others. Strength training can also help to maintain muscle mass during weight loss.1,2


Flexibility is the range of motion available to your joints. Many types of physical activity, including dancing, yoga, and martial arts, require significant joint movement, and improving flexibility may allow you to do these activities more easily and fluidly. Even daily activities such as housework and getting in and out of the car are easier with more functional flexibility, especially as we age.

Yoga, tai chi, Pilates, and stretching exercises can increase flexibility. These exercises can improve your range of motion and promote better posture and balance. However, contrary to popular belief, research on stretching has shown that it does not reduce risk of injury or later muscle soreness.3

A group of people are shown sitting on yoga mats and participating in a stretching exercise.


Balance is the ability to maintain equilibrium during movement or while stationary. Many forms of physical activity and daily living activities require balance. Exercises to improve balance are especially important in older adults, as balance tends to deteriorate with age, putting older adults at greater risk of falls and fractures.4 Activities that can improve balance include walking backward, standing on one leg, and using a wobble board. Activities such as tai chi and yoga can also improve balance, and especially for older adults, can also count as moderate-intensity aerobic activity.1

Physical Activity Benefits and Guidelines

Regular physical activity is one of the best things you can do to achieve optimal health. Individuals who are physically active for 150 minutes per week lower the risk of dying early by 33 percent compared to those who are inactive.3 The 2018 Physical Activity Guidelines for Americans were issued by the Department of Health and Human Services (HHS) to provide evidence-based guidelines to Americans aged three and older about how to improve health and reduce chronic disease risk through physical activity. The full guidelines are available online at the following link: Physical Activity Guidelines for Americans.4


Key Guidelines for Adults

• Adults should move more and sit less throughout the day. Some physical activity is better than none. Adults who sit less and do any amount of moderate-to-vigorous physical activity gain some health benefits.

• For substantial health benefits, adults should do at least 150 minutes (2 hours and 30 minutes) to 300 minutes (5 hours) a week of moderate-intensity, or 75 minutes (1 hour and 15 minutes) to 150 minutes (2 hours and 30 minutes) a week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity aerobic activity. Preferably, aerobic activity should be spread throughout the week.

• Additional health benefits are gained by engaging in physical activity beyond the equivalent of 300 minutes (5 hours) of moderate-intensity physical activity a week.

• Adults should also do muscle-strengthening activities of moderate or greater intensity and that involve all major muscle groups on 2 or more days a week, as these activities provide additional health benefits.

Source: 2018 Physical Activity Guidelines for Americans

Improving your overall fitness involves sticking with a physical activity program on a regular basis, so that being active becomes part of your routine. Choosing physical activity that you enjoy will increase the likelihood of sustaining the activity. If you are nervous or unsure about becoming more active, check with your doctor about the best way to get started. The good news is that moderate-intensity activities such as brisk walking are very safe for most people, and the health advantages of becoming active far outweigh the risks. Physical activity can also be social; regularly meeting a friend for a walk or joining a hiking group can make getting active more fun and social, plus help you stick to your plan. Physical activity provides a wealth of benefits—physical, mental, and emotional.

Two men walking down a path in a park with fall leaves on the trees and ground.

Physical Benefits

Mental and Emotional Benefits

Longer life: A regular exercise program can reduce your risk of dying early from heart disease, certain cancers, and other leading causes of death.

Mood improvement: Aerobic activity, strength-training, and more contemplative activities such as yoga, all help break cycles of worry and distraction, effectively draining tension from the body.

Healthier weight: Exercise, along with a healthy, balanced eating plan, may help you lose extra weight, maintain weight loss, or prevent excessive weight gain.

Depression relief: Exercise can produce antidepressant effects in the body. Studies have shown that physical activity reduces the risk of and helps people cope with the symptoms of depression.

Cardiovascular disease prevention: Being active boosts HDL cholesterol and decreases unhealthy triglycerides, which reduces the risk of cardiovascular diseases.

Cognitive skills retention: Regular physical activity can help people maintain thinking, learning, and judgment as they age.

Management of chronic conditions: A regular routine can help to prevent or manage a wide range of conditions and concerns, such as metabolic syndrome, type 2 diabetes, depression, arthritis, and certain types of cancer.

Better sleep: A good night’s sleep is essential for clear thinking, and regular exercise promotes healthy, sound sleep. It can also help you fall asleep faster and deepen your rest, promoting better mental and emotional wellbeing.

Energy boosts: Regular physical activity can improve muscle tone and strength and provide a boost to your cardiovascular system. When the heart and lungs work more efficiently, you have more energy.

Strong bones: Research shows that aerobic activity and strength training can slow the loss of bone density that typically accompanies aging.

Table 10.1. Physical and emotional benefits of exercise.

The FITT Principle

One helpful tool for putting together an exercise plan is the FITT. FITT stands for:

  • Frequency – how often you exercise
  • Intensity – how hard you work during your exercise session
  • Time – how long you exercise for
  • Type– what kind of exercise you do


You can manipulate the principles of FITT to better meet your exercise goals and to boost your motivation to exercise. You will be more likely to stick to a workout plan that is fun, has flexibility, and works with your lifestyle. By changing up the types of exercise you do, varying the intensity of your workouts, and choosing days of the week and times of the day that work best with your schedule, you can create a plan for success with your exercise goals. As you design your physical activity plan, make sure you find ways to move that you truly enjoy and can sustain and consider the components of the FITT principle to establish more detailed goals and create purpose for your workouts.




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Nutrition: Science and Everyday Application Copyright © 2020 by Alice Callahan, PhD; Heather Leonard, PhD, RDN; and Tamberly Powell, MS, RDN is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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