Mobility vs Flexibility - What's the Difference?

Some fitness professionals use the words mobility and flexibility interchangeably. But it's important to know that although they are related terms, they mean different things.

In simple terms, flexibility is the ability of the soft tissues (muscles, ligaments, tendons) to passively stretch. Mobility, on the other hand, is the joint's (i.e., the point where two bones meet) ability to actively move through its full range of motion.

Both mobility and flexibility are important components of healthy movement. Good mobility requires flexibility in the muscles and other soft tissues surrounding the joint. But, keep in mind, mobility also requires strength and stability. So, it's possible for an individual to be flexible but lack mobility.

Why Are Flexibility and Mobility Important?

Flexible muscles and joints allow the joints to move through the proper range of motion. So, if a muscle lacks flexibility, an individual's mobility is also impacted. This, in turn, can alter movement and posture, impact performance, and increase the risk of injury. But, keep in mind, we aren't just talking about athletes. Everyday movements like sitting, walking, and reaching all require flexibility and mobility. So, both flexibility and mobility play a key role in the quality of life.

In addition, healthy movement includes a combination of joints that aren't supposed to move (immoveable), joints that have limited movement, and other joints that allow for a much broader range of motion. Functional movements typically require a blend of different joints working together to stabilize, support, and move the body. So, having the strength and stabilization to support the appropriate joints while another joint is moving and keeping those joints in a safe and optimal position is important.

Before unraveling ways you can help clients improve their flexibility and mobility, learn about some of the factors that play a role in an individual's ability to stretch and/or move.

Factors That Can Influence Flexibility

The following list includes a few of the factors that impact an individual's flexibility:

• Genetics: Genes play a large role in an individual's natural flexibility (1).

• Age: Flexibility typically declines with age (2).

• Injury: Pain, scar tissue, etc., can limit the range of motion.

• Hormones: Pregnancy hormones can increase the elasticity of the connective tissue in the body (3).

• Gender: Females tend to be more flexible than males.

Factors That Can Influence Mobility

The following list includes a few of the factors that impact an individual's mobility:

• Joint structure: Different types of joints allow for different movements.

• Age: Joint mobility typically declines with age (4).

• Soft tissue flexibility: Proper elasticity in the muscles, tendons, and ligaments are essential for a full range of motion.

• Overall health: Certain health conditions can impact an individual's mobility.

• Fat/muscle mass: Excess fat or excess muscle can impact movement.

Check out the ISSA blog for ways you can help clients improve ankle mobility and how to use corrective exercise for better shoulder mobility.

Flexibility and Mobility Physiology Components

There are a variety of different receptors in the body that provide almost instant feedback to the central nervous system (CNS). Before exploring how to improve flexibility and mobility, it's important to have a basic understanding of two of those receptors that work together to protect the muscle from injury.

Muscle Spindles

Inside the muscle, there are sensory receptors called muscle spindles. They communicate changes in length or rate of change in the muscle. The muscle spindles play a role in protecting the muscles from stretching too far. To simplify, when a muscle stretches, the muscle spindles send a message to the nervous system to contract the muscle to protect it from overstretching (also called the stretch reflex) (5).

Golgi Tendon Organ

Another important sensory receptor is the Golgi tendon organ (GTO). These receptors are located at the end of the muscle (near the tendon). Opposite of muscle spindles, they sense changes in tension and the rate of tension in a muscle (6). When they sense tension, they cause the muscle to relax.

Flexibility Exercises

There are a couple of ways you can use the physiology information to improve a client's flexibility.

Self-Myofascial Release (SMR)

Foam rolling or other types of SMR are a great way to reduce tension in the muscle and support greater flexibility (7). It's believed that when a client puts pressure on part of the muscle for a period of time (using the foam roller, trigger point ball, or something similar), receptors in the body respond by inhibiting the muscle spindle (helping the muscle relax) (8).

You can learn more about foam rolling and SMR here.

Static Stretching

This form of stretching is what most people think of when they hear the word stretching. Static stretching can be incredibly effective at helping clients improve their flexibility. During a static stretch, the client stands (or sits) in one position while holding a stationary stretch for several seconds (i.e., hamstring stretch, quad stretch, etc.) (9). Although there has been some variance, it's generally accepted that static stretching should be done slowly and consistently, and should be held for 15-30 seconds. This helps train the muscle and connective tissue to adjust to the new length instead of trying to contract (via the stretch reflex) (10).

Keep in mind, there are a handful of different types of stretching that can improve flexibility, not just those listed in this article. For more information on different types of stretching, check out this article.

Mobility Exercises

In addition to increasing flexibility, dynamic stretching is an effective way to improve a client's mobility (11).

Dynamic Stretching

This type of mobility exercise is different from what most people think of when they hear the word stretch. Ultimately, dynamic stretches are active movements that allow the muscle tissue to warm up, stretch, and take the joints through the full range of motion.

Ideally, a dynamic stretch should mimic the movement(s) your client plans to perform or engage the muscles and joints that will be used. A few examples of mobility exercises include the walking lunge, high knees, and hip circles.

Want to learn more about improving the body's alignment so you can help your clients move, perform, and get better results? Check out ISSA's Corrective Exercise Specialist Course!

References

1. Battié, M.C., et.al. "Heritability of lumbar flexibility and the role of disc degeneration and body weight." J Appl Physiol (1985). 2008 Feb;104(2):379-85.

2. Stathokostas, Liza., et al. "Flexibility of older adults aged 55-86 years and the influence of physical activity." Journal of aging research. vol. 2013 (2013).

3. Cherni, Y., et. al. "Evaluation of ligament laxity during pregnancy." Journal of Gynecology Obstetrics and Human Reproduction. 2019; 48(5):351-357.

4. Medeiros, Hugo Baptista de Oliveira, et al. "Age-related mobility loss is joint-specific: an analysis from 6,000 Flexitest results." Age (Dordrecht, Netherlands) vol. 35,6 (2013): 2399-407.

5. Banks, R., "Muscle Spindles and Tendon Organs." Reference Module in Biomedical Sciences, Elsevier, 2018.

6. Moore, J.C. "The Golgi Tendon Organ: A Review and Update." American Journal of Occupational Therapy, April 1984, Vol. 38, 227-236.

7. Zhang, Q., Trama, R., Fouré, A., & Hautier, C. A. (2020). The Immediate Effects of Self-Myofascial Release on Flexibility, Jump Performance and Dynamic Balance Ability. Journal of human kinetics, 75, 139-148.

8. Hou C-R, Tsai L-C, Cheng K-F, Chung K-C, Hong C-Z. Immediate effects of various therapeutic modalities on cervical myofascial pain and trigger-point sensitivity. Arch Phys Med Rehab 2002;83: 1406-14

9. Nishikawa, Y., Aizawa, J., Kanemura, N., Takahashi, T., Hosomi, N., Maruyama, H., Kimura, H., Matsumoto, M., & Takayanagi, K. (2015). Immediate effect of passive and active stretching on hamstrings flexibility: a single-blinded randomized control trial. Journal of physical therapy science, 27(10), 3167-3170.

10. Appleton, B. "Stretching and Flexibility." web.mit.edu. 1996 (last modified 2009). Version 1.36. https://web.mit.edu/tkd/stretch/stretching\_toc.html#SEC5. Accessed August 2021.

11. Iwata, M., Yamamoto, A., Matsuo, S., Hatano, G., Miyazaki, M., Fukaya, T., Fujiwara, M., Asai, Y., & Suzuki, S. (2019). Dynamic Stretching Has Sustained Effects on Range of Motion and Passive Stiffness of the Hamstring Muscles. Journal of sports science & medicine, 18(1), 13-20.