Becoming and staying physically fit throughout life is an important part of achieving optimal health. A well-rounded exercise program can improve  health in a number of ways. It promotes weight loss, strengthens muscles and bones, keeps the heart and lungs strong, and helps to protect against chronic disease. There are four essential elements of physical fitness: cardiorespiratory endurance, muscular strength and endurance, flexibility, and maintaining a healthful body composition. Each component offers specific health benefits, but optimal health requires some degree of balance between all four.

Some forms of exercise confer multiple benefits, which can help balance the different elements of physical fitness. For example, riding a bicycle for thirty minutes or more not only builds cardiorespiratory endurance, it also improves muscle strength and muscle endurance. Some forms of yoga can also build muscle strength and endurance, along with flexibility. However, meeting fitness standards in all four categories generally requires incorporating a range of activities each day. As we exercise regularly, our bodies will begin to change and we’ll notice that we’re able to continue exercising  with greater ease.

The Essential Elements of Physical Fitness

Cardiorespiratory Endurance

Cardiorespiratory endurance is built by aerobic training, which involves activities that increase your heart rate and breathing such as walking, jogging, or biking. Aerobic exercise is continuous exercise (lasting more than 2 minutes) that can range from low to high levels of intensity. It increases heart and breathing rates to meet increased demands for oxygen in working muscles. Regular, moderate aerobic activity— about thirty minutes at a time for 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 each heartbeat boosts your ability to supply your body’s cells with oxygen and nutrients, to remove carbon dioxide and metabolic wastes. It also leads to a lower resting heart rate for healthy individuals. In addition to the benefits of aerobic training for cardiovascular health, it is also an excellent way to maintain a healthy weight.

Muscle Strength

Muscle strength 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 high intensity training is used to build muscle strength with short, high-intensity activities. Building muscle strength and endurance is not just crucial for athletes and bodybuilders—it’s important for children, seniors, and everyone in between. The support that your muscles provide allows you to work, play, and live more efficiently.

Strength training 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, and other exercises to build your muscles. If strength training is performed at least twice a week, it can help to improve muscle strength and to increase bone strength. It can help manage health conditions like diabetes, arthritis, dementia, hypertension, and many others. Strength training can also help you to maintain muscle mass during a weight-loss program.¹

Flexibility

Flexibility is the range of motion available to your joints. Yoga, tai chi, Pilates, and stretching exercises work to improve this element of fitness. Stretching not only improves your range of motion, it also promotes better posture, and helps you perform activities that can require greater flexibility, such as chores around the house. In addition to working on flexibility, older adults should include balance exercises in their regular routine. Balance tends to deteriorate with age, which can result in falls and fractures.²

Body Composition

Body composition is the proportion of fat and fat-free mass (which includes bones, muscles, and organs) in your body. A healthy and physically fit individual has a greater proportion of muscle and smaller proportion of fat than an unfit individual of the same weight. Although habitual physical activity can promote a more healthful body composition, other factors like age, gender, genetics, and diet contribute to an individual’s body composition. You can refer back to Unit 7 for a detailed discussion on body composition, how it is measured, and how it is used as an indicator for health.

The Benefits of Physical Activity

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. You can review the guidelines here, including recommendations for children, adolescents, and adults.⁴