The Physiology of Stretching

When it comes to stretching, it is important to understand the basic physiology of the muscles and how they work together. The muscles can contract (when tension is generated), relax (the tension is released) and lengthen (the force applied to a muscle allows it to stretch).

Muscles are made of multiple strands of tissues called fascicles, which are bundles of muscle fibers composing of myofibrils and sarcomeres (each is made of myofilaments). These various levels of tissues operate with the help of the nerves connected to the spinal column to the muscle; an electrical signal will transmit from the nerves to the muscle fibers. This stimulates the fibers and causes the muscle to contract, relax or lengthen. When these movements occur, it affects the muscular and skeletal structure resulting in movement of your limbs or “make the bones move”.

The movement of the limbs can represent a person’s stretching / flexibility capacity. That explains why, sometimes, a same stretch can feel different from one person to another depending on their daily habits and past experiences.

All the muscles are attached to the bones by tendons and ligaments (making up the connecting tissues between the bones, in the joints). One way to reduce the chances of injury during a stretching session is to to be aware of the muscles that are being engaged and it’s capacity for the movement required during the stretching exercise — as easy as noticing fatigue, discomfort and actual pain throughout the stretch.


Flexibility is simply the accessible range of motion in a joint or group of joints (shoulders, hips, knees, etc.). Being functionally flexible (ability to be active and passive in the motion) helps to move the joints effectively through a complete range of motion without feeling pain or feeling restricted. Lacking functional flexibility will have an important impact on the health of the cartilages and other structures within the joints. This may cause weakness that will fatigue the muscles quickly, which causes the opposing muscle groups to compensate and work harder – leading to muscular and joints imbalance/further injury. It is recommended to learn different types of stretching and how to effectively stretch without causing/aggravating supposed injury.

Types of Stretching

There are multiple types of stretching that can be used during a training which has different impacts on the body. There are passive stretches (relaxed muscles) and active (engaged muscles) which can be dynamic or static.

During a passive dynamic stretch, movements of relaxed limbs move from point A to point B without any engagement; when it is static the targeted muscles will be hold in a same position for a set period of time.

While doing an active dynamic stretch the muscles are engaged and they will move around the joint. Whilst during an active static stretch, the muscles are engaged to hold the position for a set period of time (also known as an Isometric Hold).

It is possible to do these types of stretching with the help of a partner or accessories (weights, bands, yoga blocks, PVC pipes, etc.) to intensify the stretch by putting external pressure on the body.

There are advanced combinations / variations of stretching to note such as Ballistic Stretching, PNF Stretching (Proprioceptive Neuromuscular Facilitation) amongst others that are considered advanced and should be practiced with caution and guidance as necessary.

Why, When and How to Stretch

Three important questions to answer to when it comes to stretching are: Why? When? And how?

It is important to stretch as the lack of it, when combined with physical activities, can lead to the muscles getting shorter, reduced range of motion and dysfunctional leading to higher possibilities of injuries.

Stretching is accessible for everybody and at any time of the day. The type of stretching will however differ before and after an activity. Before the physical activity, it is recommended to do more of dynamic stretching to warm the muscles by moving around. After the physical activity, doing static stretching helps to lengthen the muscles and relax the body.

It is also good to know some essentials that can help deepen the stretch properly and pain-free: Some experts say not to bounce while stretching, because bouncing can cause the muscles to tighten which can lead to some muscle injuries — though similar to Ballistic Stretching it should be exercised with care and experience or under supervision. It is common to think that it is normal to feel pain when stretching — which leads us to have an introspection of differentiating discomfort and pain. Feeling pain during the stretching exercise implies the muscles / joints have been pushed beyond its capacity. Some experts advise to make the stretch sport specific, meaning that the stretches will involve the muscles used during the sport or activity practiced before and after the stretching exercises.


There is still much more to cover when discussing stretching and flexibility. Having basic understanding of the physiology of stretching, knowing the main points of how and when to stretch is important when starting a new ‘stretching journey’. To learn more visit

*Informational purposes only. It is advised to seek Professional attention before beginning any exercise or nutritional program.