Why Flexibility, Mobility and Stability Are So Important to a Successful Fitness Routine

Sailors perform a stretching exercise in the hangar bay of the aircraft carrier USS Harry S. Truman (CVN 75).
Sailors perform a stretching exercise in the hangar bay of the aircraft carrier USS Harry S. Truman (CVN 75), Dec. 15, 2013. (Mass Communication Specialist Seaman Blagoj B. Petkovski/U.S. Navy photo)

Flexibility, mobility and stability are elements of fitness that help us bend, move and stay in control of our movements, respectively. All are important pieces to help our bodies to move through our environment with a reduced injury risk.

If we regularly stretch, move, balance and strengthen our muscles and joints, we will improve our flexibility, mobility and stability. See how they are related to one another, as defined below, to better explain how to implement them into our daily lives:


Of the three terms, flexibility is the easiest to understand, as we often see stretching used in various ways, including warm-ups, cooldowns, yoga classes and other movements. Stretching can make us more flexible, mobile and stable.

Think of flexibility as the soft tissues (muscles and tendons primarily) that allow for a certain range of motion within a joint by lengthening. The greater your flexibility, the greater range of motion and mobility you will have. Flexibility and mobility work together to allow for body movement during any activity.

A common demonstration of flexibility is the toe touch. Bending over at the waist with knees straight requires muscle flexibility of the hamstrings, calves, glutes and lower back. The muscles opposite this movement's stretching muscles are relaxed in a passive state. While flexibility is part of hip mobility in this example, it is not the only determining factor. The National Institutes of Health defines flexibility as "the intrinsic property of body tissues which determines the range of motion achievable without injury at a joint or group of joints."


We define mobility as moving throughout a complete range of motion without being restricted by tight muscles, tendons, ligaments, cartilage and joint health issues. Muscle flexibility, strength and motor control within the central nervous system make mobility more nuanced than flexibility, but you still cannot have mobility without it.

For mobility to occur, a group of muscles must be lengthened (stretched) on one side of the joint, while the opposite side requires the muscles to shorten (flex) to make it bend. Flexibility and strength training are required to make this happen at the greatest range of motion. For example, a biceps curl requires flexing the biceps to bring it up through the movement and the triceps to stretch. Otherwise, the elbow will not allow for that movement.

The wider range of motion from top to bottom determines joint mobility, but mobility involves much more than the range of motion in our lives. Harvard Medical defines mobility as "your ability to move purposefully throughout your day. It is the foundation for living a healthy and independent life. Mobility comprises all the skills required for everyday living: strength, balance, coordination and range of motion."


Stability is typically measured within the joint but can also be measured throughout multiple joints in any particular movement or still position. It is a function of strength, flexibility and balance, and allows the joint or multiple joints to coordinate as determined by the activity.

Think of stability as an element of fitness that involves the central nervous system, even more so than flexibility and mobility. Flexibility and mobility play their role in creating a stable joint and body, but strength and balance are critical to a joint's stability.

Doing exercises that require balance, such as lunges, squats or even side plank poses, can help build stability within the corresponding joints worked in these exercises. According to Stretch Affect, stability is defined as "your body's ability to safely and effectively maintain and control various postures and resist changes in equilibrium." Stabilizing muscles are the most important for supporting and holding your body upright.

These three elements of fitness can be easily implemented into any training program or spread throughout the day in your normal life, too. For instance, whether standing or sitting, you can occasionally stretch your legs, lower back, shoulders, and arm and neck muscles. Setting a timer for 45-60 minutes to stand up and stretch is highly beneficial to offset the tightening effects of sitting all day. But you can end your workout for 10-15 minutes with various stretching activities. Ideas for workout and flexibility cooldowns.

Since mobility is movement, get up throughout the day and walk for 3-4 minutes. Walk up and down a flight of stairs, stopping to stretch and move your ankles, knees and hips through a range of motion greater than just sitting or standing idle allows.

Adding balance drills to your day is one of the easiest ways to include stability training. From standing in line on one leg to getting in the prone position and doing push-ups or plank poses with an arm or leg lifted off the floor, stability/balance training will build strength in these joints.

If sitting, hold a weight over your head and work shoulder stability by holding it for 30-45 seconds. A next-level way to build stability is to stand on one leg and close your eyes. You will then feel the muscles required to help you stand upright. Any standing exercise, such as dumbbell biceps curls, can enhance stability by standing on one leg.

Practicing stretching, movements and strengthening with balance drills is as important to our health as cardiovascular, strength training, eating well and sleeping. Adding these easy activities to your day can make a difference in how you feel when you move and may even help you prevent pulling muscles, spraining joints or falling.

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Stew Smith is a former Navy SEAL and fitness author certified as a strength and conditioning specialist (CSCS) with the National Strength and Conditioning Association. Visit his Fitness eBook store if you're looking to start a workout program to create a healthy lifestyle. Send your fitness questions to stew@stewsmith.com.

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