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Flexibility, a concept necessary among many different factors and aspects of life, and this week, specifically, one of many training concepts to highlight. Flexibility training contributes to much more than just the typically thought of fancy dance moves and yoga poses (though, each of those demonstrate immense athletic ability, and one should not overlook them), but to overall balance for well-being and improved movement patterns throughout the completion of daily activities. This article will discuss the physiological factors of flexibility training, including the adaptations that take place as a result, explanations of some common modes and training variables for improving flexibility, and specific benefits of flexibility training as it pertains to everyday life and athletic performance. 

Flexibility is defined as the normal extensibility of the muscles and other non-contractile structures (ligaments and tendons) surrounding a joint that allow the joint to move through its specific range of motion. It depends on several factors, including: mobility (the joint structure can only obtain efficient extensibility if arthromatic bodily control is maintained throughout the joint’s range of motion, optimally), myofascial tissue elasticity, genetics, body composition, age, sex, activity level, history of injury, and repetitive movement patterns. A person’s flexibility also stems from three trainable elements within the body: mechanical (structural), neural (CNS and PNS), and psycho-social (ability to tolerate a stretch). To briefly explain, we must first start with two mechanical structures found within the muscle and joint tendons that facilitate the reactions that occur during stretching. First, the muscle spindle – a sensory organ found within the muscle, parallel to the muscle fibers, that corresponds with the central nervous system by sending information about the change in muscle length and rate of that change as stretching occurs. The muscle spindle prevents the muscle from overstretching at a rate beyond the muscle’s capacity, preventing injury and maintaining muscular tone. Second, the Golgi Tendon Organ (GTO), lies within the cohesion of the muscle and tendon and sends information to the CNS regarding changes in the amount and rate of tension applied to the muscle. 

When a muscle is stretched, many neurological reactions take place that allow the stretching of the muscular structure to occur, affecting the previously discussed mechanical structures and producing an overall lengthening reaction, or stretch response. This response occurs due to two deeper reactions that take place within the muscle, autogenic inhibition and reciprocal inhibition, each contributing to the rationale for different stretch techniques, as described later in the article. Autogenic inhibition involves prolonged activation of the GTO, which will inhibit activity of the muscle spindle, and takes place when muscular tension from neural impulses is greater than the neural impulses that cause contraction of the muscle. Reciprocal inhibition occurs when one muscle contracts and its antagonist (the muscle opposite of the one creating the movement) relaxes. For example, as the biceps contact to create elbow flexion , the triceps (antagonist muscle) extend, or relax, further allowing the movement.  

Various modes of training exist that implement these physiological factors in order to elicit optimal results. Stretching, perhaps the most commonly recalled mode of flexibility training, consists of its own sub-types with benefits varying among each. Static stretching involves the prolonged passive lengthening of a muscle to a point of tension. During static stretching, driven by the process of reciprocal inhibition, the muscle is lengthened and the muscle spindle simultaneously activates. This process then activates a stretch reflex, contracting the target muscle, and eventually producing a relaxation response from the muscle spindle, causing the muscle to lengthen. Some common examples of static stretching include, but are not limited to: sit and reach, 90/90 Hamstring stretch, standing adductor stretch (standing in a side lunge position), and standing calf stretches. These stretches should be held for 20-30 seconds, and performed 1-3 times as needed. Active stretching and dynamic stretching also result from reciprocal inhibition and consist of dynamically moving the joint throughout its range of motion. Active stretches involve moving the joint to a specific position, holding for 2-3 seconds, and then repeating that movement for 5-10 repetitions per set. Dynamic stretches involve fluid, continuous movement throughout the entire range of motion of the joint for 10-15 repetitions per set. Typically resembling the movement of the specific activity soon performed, active and dynamic stretches should usually take place during the warm-up period of a workout. Examples include: leg swings, side lunges, Frankensteins, and knee-hugs. 

The final technique presented does not include “stretching” per say, but does use the aforementioned autogenic inhibition response to increase overall mobility of a joint. Self-myofascial techniques utilize various modalities to target specific fascial adhesions surrounding a given muscle and contributing to muscle tightness and soreness. Scientific theories on the mechanisms of self-myofascial techniques include possible explanations for both mechanical and neurophysiological adaptations when using the technique. Mechanically, compression from the modality (foam roller, stick, ball, etc.) increases blood flow to the tissue and helps break up restrictions and adhesions of the muscle fascia, causing the tissue to “relax”. Neurophysiologically, tissue relaxation may be influenced by the compressive stimulation of mechanoreceptors (GTO and muscle spindles) and pain receptors. When self-myofascial rolling, roll along the targeted muscle belly until you find a tender area, and then hold the roller or ball on that area for about 30 seconds or until you no longer feel tenderness. Perform for 1-3 sets as needed. (Sutton, 438-478)

Flexibility remains a key concept for fitness training, and it should be included with any training program. Lack of flexibility can lead to muscle imbalances, poor posture, improper movement patterns, and even injury, and unfortunately, many people suffer from the lack of this vital training concept. Try implementing even just 10 minutes of stretching during your day (before heading to work, during a lunch break, or even in the evening as you watch TV), and feel the difference it can make in your overall wellness!