How Flexible Are You: What Determines Flexibility and How Can It Be Improved?

There are several factors that determine the flexibility of a person. These factors include muscle fiber length, joint structure, and connective tissue suppleness, among others.

Flexibility Explained

Flexibility is an inherent property of tissues in the body. It determines the motion range that a person can achieve without injuring a joint or group of joints. Such a definition was made by Dalhousie University kinesiologists, who presented during the 13th International Conference on Biomechanics in Sports.

The kinesiologists note that beyond connective tissue and muscle, another crucial factor that can tell a person's flexibility is how the skeletal structures of a person fit with one another.

Physical therapist Stephen Dunn, who is also the co-founder of Core Therapy and Pilates in Texas, shares that inherent flexibility differences across individuals could be quite big, with genetics having a crucial role. There are several genetically inherited traits that may affect one's flexibility. Such traits include muscle fiber length and joint structures, among others.

Dunn explains that some flexibility is naturally lost with age. This is due to ligament and tendon alterations. These make up connective tissues that end up losing elasticity over time. Tendons link joint bones to muscles that manipulate them. On the other hand, ligaments support and surround the joint, controlling its ways of movement.

Dunn explains that elastin and collagen are two proteins that are crucial for the preservation of the connective tissues' elasticity and flexibility. The formation of collagen declines with age, while existing collagen ends up stiffening and becoming brittle.

There are also other age-related changes in the joints that could affect flexibility. These include the wear and tear of cartilage and age-related muscle loss. This explains why young people are more flexible compared to older adults.

Aside from these, other factors can also impact flexibility. Sex, for one, can play a role. The female sex hormone estrogen boosts collagen levels within the connective tissues. This makes the ligaments and tendons of females more flexible and elastic compared to males.

Moreover, hypermobility disorders may also affect one's degree of flexibility. These conditions typically have a genetic cause and can change connective tissues. People with these conditions may exhibit excessive motion range in their joints.

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Stretch To Boost Flexibility

Physical activity can also affect flexibility. Dunn explains that a sedentary lifestyle could lead to decreased motion range and stiffness.

With that, flexibility can also be boosted through physical activity changes, such as the adoption of a stretching routine. According to the American College of Sports Medicine, it is recommended to stretch at least two to three days a week, or even daily.

During a stretch and briefly after the stretch, this activity could lengthen the muscle-tendon unit linked to a joint. It could help with counteracting stiffness that could have surfaced due to a static sitting position. Over time, regular stretching could boost motion range by increasing one's levels of tolerance for stretching.

Such an idea, also referred to as the sensory theory for increasing muscle extensibility, suggests that increased muscle stretchiness that is observed right after a stretching session or after a couple of weeks is solely because of sensation changes.

Dunn explains that when it is first stretched, a muscle contracts due to how the spindles of the muscle relay signals to the spinal cord, which then sends another message back to the muscle. This is because of the stretch reflex, which is an involuntary defense against potential muscle damage and overstretching.

However, with repetitive stretching, the neural systems get acclimated to the stimulus of stretching. This allows the joint to have a greater motion range before activating the stretch reflex. With this, people can exhibit differences in how much they can modify their stretch tolerance with the same stretches.

All kinds of stretching can boost flexibility. These include static, dynamic, and pre-contraction stretching. There is also evidence that shows that eccentric contractions could also boost flexibility. Certain low-impact exercises, such as pilates and yoga, can also engage different stretching modes and improve one's motion range.