In the world of fitness, terminology often gets blurred. In particular, range of motion (ROM), flexibility, and stretching frequently fall prey to this exact scenario. While many fitness professionals and physical therapists may use these terms interchangeably, we must understand the nuances of each related yet distinct concept. This article attempts to clarify these distinctions and delve into the various types of each and how they work together to keep individuals fit and mobile.
Clarifying Mobility
Mobility and flexibility, two words often used interchangeably, both affect how well an individual can move through his surroundings. They describe two actions that, while connected in several ways, are not the same thing. Mobility refers to how a joint moves through its normal range of motion (ROM). Some define it as the ability to actively control ROM. That range of motion will vary greatly, depending on the type of joint in question. A hinged knee joint moves backward and forward but can also rotate inward and slightly outward. The ball-and-socket joint of the shoulder enables an individual to lift and lower his arms, moving them in circular and back-and-forth motions. Not only does mobility affect how well one can perform workouts, but it also plays a key role in staying injury-free.
Flexibility Explained
Flexibility refers to the ability of a joint or series of joints to move through an unrestricted, pain- free range of motion. Although flexibility varies widely from person to person, minimum ranges are necessary for maintaining joint and total-body health.
We can think of flexibility as the ability of a muscle to stretch temporarily. Comparing a muscle to a rubber band, we can more easily envision how greater flexibility affects the ease of effectively stretching that muscle. Many variables affect the loss of normal joint flexibility, including injury, inactivity, or a lack of stretching.
Inadequate flexibility could have a negative effect on one’s body in the following ways:
- Joints require movement through a full range of motion to maintain the health of cartilage and other structures within the joint. Flexibility elicits increased blood supply and nutrients to joint structures, along with increased quantities of synovial joint fluid. Many older adults observe this inflexibility in their weight-bearing joints, such as the hips and knees.
- Inflexible muscles tend to fatigue more easily, leading to muscular injuries. Also, such rigidity tends to be associated with the muscles’ inability to protect joints from more severe injuries. As a prime example, flexibility in one’s hamstrings plays a crucial role in stabilizing the knee and preventing ACL tears.
- Decreased flexibility can cause abnormal stress on structures and tissues distant from the initial site of inflexibility. Physical therapists often notice that a patient’s knee tendonitis stems from tightness in the calf muscle.
Athletes often overlook the importance of flexibility in active recovery. Including flexibility routines in one’s workout program can help foster easier breathing patterns, leading to relaxation, stress reduction, and improved recovery. Recovery comes about as flexibility enhances circulation and blood flow to the muscles. Experts believe that improving mobility and flexibility together can enhance fitness and reduce injury risk.
Range of Motion
Having a greater understanding of both flexibility and mobility, we can now move on to range of motion. This term accounts for both modifiable (soft tissue extensibility, neural control) and non-modifiable (bone structure) factors, whereas flexibility is only one of several trainable components of ROM.
Having a wide range of motion allows individuals to perform exercises and activities with proper form and efficient muscle recruitment. Once mastered, ROM will improve muscle power, speed, and endurance.
An individual’s range of motion aligns with the extent of mobility contained in the soft tissues surrounding a joint. These soft tissues include muscles, ligaments, tendons, joint capsules, and skin. Physical therapists consider many factors that can lead to reduced joint ROM. Muscular tightness almost always tops the list. This condition results from an increase in tension from active and/or passive mechanisms. Passively, muscles shorten either through postural adaptation or scarring; actively, muscles may shorten due to involuntary spasms. Regardless of the cause, tightness limits the range of motion and may, over time, create a muscle imbalance.
Personal trainers and physical therapists often speak of “passive” and “active” ranges of motion. One’s active range of motion commonly refers to one’s ability to move a joint through its complete range of motion without assistance. We observe this when a client performs standing knee raises, lifting the knee towards the chest without pulling on the knee. The active range of motions applies more to the concept of mobility. Conversely, passive range of motion involves an individual receiving assistance with a joint’s movement. The client does not actively engage the muscles normally used to start the movement. Continuing with the above example, a client may pull his knee to his chest with the assistance of the personal trainer to ascertain correct body positioning. The passive range of motion typically applies more to flexibility.
Stretching
All of this discussion ultimately leads to an understanding of stretching. Stretching generally focuses on increasing the length of a musculotendinous unit, thereby increasing the distance between a muscle’s origin and insertion. Muscle tension typically follows an inverse relationship with muscle length: decreased muscle tension leads to increased muscle length, while increased muscle tension causes the muscle to shorten.
When an individual stretches a muscle, they simultaneously apply tension to other structures, such as the joint capsule and fascia, which are composed of different tissue than muscle and endowed with different biomechanical properties. A lack of stretching, especially when combined with an active lifestyle, can lead to fatigue-induced soft tissue shortening over time.
We can think of stretching as an intervention to improve flexibility and induce post-exercise relaxation. Additional benefits of regular stretching may include the following:
- Increased neuromuscular coordination
- Return of a muscle to its natural resting state
- Modifying blood pooling and encouraging recirculation
Working Together for Smoother Transitions
While stretching is a highly effective way to enhance flexibility, other methods also yield comparable gains in range of motion. Engaging in strength training at long muscle lengths and foam rolling both help elicit long-term ROM gains. Clearly, flexibility ranks as only one component of ROM.
Pure stretching boasts a diverse array of effects that extend beyond flexibility, including strength development and neural modulation. By erroneously using these terms interchangeably, not only might fitness professionals perpetuate myths, but they may also unwittingly risk selecting inappropriate exercises for a client’s workouts.
Flexibility + Muscular Strength = Mobility
Muscular strength plays a role in all of the aforementioned dynamics. Consider what goes on within the body’s structure when a client performs a full-depth squat. This move requires one to have good passive ROM (flexibility), but he also must possess sufficient strength and control over that ROM.
As we can observe during concentric and eccentric contractions, muscles can shorten, lengthen, and twist. Their ability to execute all of these movements effectively exemplifies flexibility combined with strength. The true test of muscle strength and flexibility is not the length a muscle can achieve, but how short it can get. A muscle can only lengthen in direct proportion to the amount it can shorten. True flexibility requires the ability to contract muscles to their fullest extent through their full range of motion.
When an individual passively lengthens a muscle without also maximally contracting it, several problems may arise:
- Micro tears form in the muscle, prompting the body’s immune system to patch them with fascia.
- Muscles get trained to stay over-stretched and weak.
- By over-stretching ligaments and tendons, the body must force biomechanical substitutions in the joints in order to achieve the desired range of motion. However, stretching with resistance increases one’s ability to contract with greater force (strength) through greater and greater ranges of motion (flexibility).
Applying the Proper Type of Stretch
Learning the differences among various stretching techniques can help trainers and therapists decide on a safe, therapeutic course of action for each client’s needs. Below, we outline the most common forms of stretching along with the benefits of each.
- Static Stretching: This technique involves extending the targeted muscle group to its maximum length and holding for 30 seconds. Static stretching promotes increases in ROM. The greatest change in ROM with a static stretch occurs between 15 and 30 seconds, although some professionals suggest that 10 to 30 seconds is sufficient to increase flexibility. After 2-4 repetitions of a static stretch, the body will not elicit additional muscle elongation. Static stretching proves most effective immediately following a workout.
- Dynamic Stretching: This technique uses continuous movement patterns that mimic the exercise or sport one will soon engage in. As a prudent warm-up, dynamic stretching has the potential to improve sports performance.
- Active Stretching: This type of stretching involves the muscles. To execute, one holds and maintains a stretched position with an opposing muscle group. This pose gets held for a brief 2 seconds before release, and works best with several repetitions.
- Ballistic Stretching: Since it involves a repetitive bouncing-type movement designed to stretch a targeted group of muscles, it figures prominently in athletic drills.
- Myofascial Release: This technique uses a foam roller to release tension/improve flexibility in the body’s deep tissue and underlying muscles. Back-and-forth movements over an area of 2 – 6” for 30 -60 seconds seem most beneficial; however, an individual’s pain tolerance dictates the amount of pressure applied.
- Proprioceptive Neuromuscular Facilitation (PNF): This stretch uses receptors to improve the response of both nerves and muscles throughout the body. Performed 2x/week, flexibility gains achieved through this type of stretch will typically remain. Usually, PNF calls for a partner, but one can achieve the same benefits solo by using a towel for resistance.
- Functional Stretching: A newcomer to the fitness field, this stretch typically appeals to athletes. By using free weights, athletes can train for improvements in balance, speed, and coordination.
Personal trainers and physical therapists might remind their clients/patients to practice proper breathing during these various stretch modalities; holding one’s breath while stretching is a common downfall. Above all, stretching should never be executed to the point of inducing pain. If a client/patient feels unusual discomfort during any of the above moves, discontinue immediately.
The Physiology of Autogenic and Reciprocal Inhibition
All of the aforementioned stretching techniques operate on a central premise: the stretch reflex. This reflex incorporates 2 distinct muscle receptors, the Golgi tendon organ (GTO) and the muscle spindle, which respond acutely to changes in muscle length. Changes in muscle tension also affect the GTO. Fitness professionals must take these receptors into consideration prior to assigning a particular stretching mode to clients.
When an individual performs a rapid stretch, the muscle spindle responds by initiating a reflexive contraction of the specific muscle getting stretched. If one holds the stretch for 6 seconds or longer, the GTO steps in and overrides the muscle spindle’s impulses. The resulting relaxation, or autogenic inhibition, allows for more effective stretching of the muscle tissue.
An isotonic contraction of an agonist muscle incites a reflexive relaxation of its antagonist muscle, thereby allowing it to stretch. This process, known as reciprocal inhibition, fosters relaxation of the tight muscles and hence an improved range of motion.
Overusing a muscle without also working its opposing muscle group can result in limited range of motion. If an individual only trains his biceps in the gym, without including any triceps training, the range of motion in the arms gets limited over time.
Practical Application
We can now more fully understand the subtle yet vital interdependence of flexibility, stretching, and range of motion. The first two can increase one’s available ROM, but ROM also depends on both the structure of the joint in question and the strength required to control that motion. The following suggestions can help clients maintain flexible muscles and healthy, mobile joints:
- Stretch and perform range of motion exercises regularly. Static stretches, or maintaining a stretch while otherwise staying still, help improve muscle flexibility. Dynamic stretches help foster mobility and flexibility, as they take joints and muscles through regular range -of -motion activities. Dynamic stretching also warms up the joints and muscles as a preparation for more strenuous activity, helping to avoid injury.
- Strength train. Use weights, exercise bands, or even bodyweight exercises to strengthen the muscles surrounding the joints. Stronger muscles will help support the joints, ensuring better functionality.
- Take breaks from sitting. Getting up from a sedentary position and moving around every hour or two can go a long way towards protecting joint health. The longer an individual remains in one position, the greater his likelihood of experiencing challenges in flexibility and/or mobility.
References
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