Related Terms

• Agility, ankle instability, ankle sprain, balance board, balance exercises, core musculature, dynamic balance training, equilibrium, foam stability pad, instability training, mechanoreceptors, neuromuscular training, position sense, postural control, postural sway, posture sense, pronation, proprioception, proprioceptors, sensorimotor training, stability ball, static balance training, synergistic dominance, vestibular system, wobble board.

Background

• Overview: Balance training uses controlled instability to help individuals discover the limits of stability, or the point at which they begin to lose control, and expand that limit. Balance training emphasizes functional movement patterns in a multisensory environment.

• Some use the term instability training instead of balance training because balance training involves putting one's body in situations where balance is threatened, therefore exercising the muscles and sensory systems as the body works to reach and maintain balance.

• The National Academy of Sports Medicine defines balance as the ability to maintain the body's center of gravity within its base of support. According to the U.S. Surgeon General, balance is a component of physical fitness related to the maintenance of equilibrium.

• Sensorimotor control: Balance is maintained through a complex interaction between the body's central nervous system, peripheral nervous system, and muscular system. The interactions between the three systems, which are continuous, are called sensorimotor control.

• Proprioception is an individual's ability to sense or "know" the body's position in space and plays an important role in the control of body movement.

• Motor commands are issued based on input from sensory receptors, or proprioceptors.

• The four main proprioceptors for sensorimotor control are kinesthetic receptors, neuromuscular spindles, Golgi tendon organs, and the vestibular system of the inner ear. Kinesthetic receptors monitor joint movement and are located within synovial joints, which allow free movement, assisted by synovial fluid contained within a synovial membrane. Neuromuscular spindles monitor increases and decreases in muscle tension and are located within skeletal muscles. Golgi tendon organs (also called neurotendinous receptors) are located within tendons and detect when a muscle stretches and contracts. The vestibular system, located in the inner ear, detects position and movement of the head. The vestibular system is a fluid-filled network of canals with hair cells on their bases.

• The sensorimotor control system operates concurrently with the human movement system, providing postural stability and, with the human movement system, joint stability.

• The central nervoussystemreceives visual inputs, vestibular inputs from the inner ear, and proprioceptive inputs and establishes balance by usingmotor controls delivered through and monitored by the sensorimotor control system.

• The cumulative input to the central nervous system from all receptors provides individuals with a sense of position and limb movement, or proprioception.

• Balance-training objectives: Balance-training objectives include increased proprioception, better muscle coordination, and reduced reaction times.

• Static balance is the ability to maintain equilibrium at rest; dynamic balance is the ability to maintain equilibrium while moving.

• Balance is a skill-related component of physical fitness. Other skill-related components are agility, coordination, power, reaction time, and speed.

• Health-related components of physical fitness include body composition, cardiovascular fitness, flexibility, muscular endurance, and muscle strength.

• Even though balance may be examined as a skill-related aspect of physical fitness, balance training must necessarily accommodate other skill-related components, such as agility, as well as health-related components of physical fitness, such as flexibility and endurance.

• Balance training is used to improve performance by increasing efficiency and coordination between nerves and muscles, enhancing movement, and decreasing unwanted movement.

• Researchers theorize that balance training reduces the incidence of anterior cruciate ligament (ACL) and ankle injuries and reduces reinjury to those areas as well.

• Balance training is integrated into some postinjury physical therapy programs and as part of treatment for individuals with certain movement disorders. Injuries for which balance training has been used include injuries to the foot, ankle, shin, calf, knee, hip, and trunk. Ankle sprains are the most common, especially among athletes. Other injuries for which balance training may be part of rehabilitation include Achilles tendentious, Achilles tendon ruptures (postsurgery), shin splints, calf strains, ACL tears and ruptures, hamstring maladies, and lower-back problems.

• Since the ability to maintain balance decreases with age, some balance-training programs address the needs of senior citizens.

• Addressing strength and flexibility as well as balance is important because the body uses muscle power, strength, and flexibility to maintain balance when balance is threatened, as it might be by sudden or unexpected loads. Most who participate in sports will have to respond to sudden or unexpected loads.

• Balance-exercise apparatuses, specifically balance boards and wobble boards, were used at first in therapeutic situations. Currently athletes in training use these apparatuses.

• History: Nobel laureate neurophysiologist Charles Sherrington coined the term proprioception in 1906. In his book, The Integrative Action of the Nervous System, Sherrington describes the role of the nervous system in monitoring and controlling body functions. The book also describes the operation of postural reflexes and the role of stretch reflexes in the body's antigravity muscles (so-called since they counteract the pull of gravity) in maintaining balance. (Muscle contraction in response to stretching a muscle is called a stretch reflex.)

Technique

• Balance exercises without apparatuses: Some balance-training exercises do not require apparatuses and may be added to calisthenic routines. The U.S. National Institutes of Health (NIH) describes several exercises on its National Institute on Aging Web site.

• A starting point for balance training may be standing on one leg on firm ground. For stability, an individual may hold on to a chair back or countertop with one hand. Then, he or she lifts one leg off the ground and maintains balance for 10 seconds. The exercise is then repeated with the other leg. The NIH recommends continuing through 10-15 repetitions. As skill increases, the individual may try the exercise without holding a support. The individual may challenge himself or herself further by doing the exercise with eyes closed, swinging the free leg, or attaching an elastic loop to the supporting leg and pulling. Balancing on one leg is also the basis for several exercises using an apparatus such as a foam pad.

• A second balance exercise is the heel-to-toe walk. An individual places the heel of one foot in front of the toe of the other foot, then picks a distant point to focus on. To begin the exercise, the back foot is moved forward and placed heel-to-toe in front of the other foot. The individual should do 20 steps. If he or she feels unsteady doing the heel-to-toe walk, the individual may do the exercise near a wall so that he or she may reach out for support if needed.

• The NIH also describes a balance walk in which the individual raises his or her arms from their sides to a horizontal position. While focusing on a distant spot, the person walks in a straight line, one foot in front of the other. With each step, the individual "lags" the rear foot by lifting it and holding it for a second before stepping forward. The NIH suggests doing 20 steps, alternating legs.

• The NIH recommends that balance exercises be done in conjunction with strength-building exercises. The NIH includes strength exercises such as the back leg raise, side leg raise, knee curl, and toe stand as exercises that enhance both strength and balance. (The NIH provides examples of endurance and flexibility exercises in addition to strength and balance exercises.)

• Exercise or physical therapy may be more effective if it reflects circumstances found in the sports for which an individual is training. To their calisthenic routines, athletes may add lunges, jumps, and drops, activities that may be more vigorous than those found in programs undertaken as part of a regular fitness program or a rehabilitation program.

• Balance exercises in rehabilitation: The University of Michigan Health System offers an exercise program, broken into three phases, intended to help individuals recovering from ankle sprains. First, ankle-stretching exercises begin when the patient can tolerate pressure on the ball of the foot. A second series of exercises that begin when ankle swelling stabilizes (stops increasing) involves rotation and other ankle movements. Finally, a third set of exercises starts when the patient can stand on the injured ankle without pain. Balance exercises are included in this final stage, after some strength and agility have returned. These include a one-legged balance exercise, jumping rope with both legs and then with one leg only, and a set of exercises using a wobble board.

• Balance-training aids: A range of equipment is available to provide a controlled degree of imbalance. Some training aids, including balance boards, wobble boards, pivot boards, and inflatable balance pods, provide a raised platform for one's foot or feet. The platform's support is designed in such a way that the platform can move above the support in response to slight changes in an individual's center of gravity.

• Other balance exercise aids include Swiss balls, balance discs, foam pads, foam rollers, multislant boards, and slide boards.

• Balance boards: There are three main types of balance boards. The simplest, a "rocker board," is a 12-inch-wide, 16-inch-long sturdy plank with a lengthwise strip attached to the bottom that raises the surface about two inches, thus creating imbalance on a single plane. Another type of balance board has a sturdy plank long enough so that the individual can stand with feet roughly shoulder-width (about 33 inches) and wide enough so that the feet can be supported without hanging over the sides. The plank rests, unattached, on a cylinder about four inches in diameter. A third type of balance board is a wobble board, which is a square or round platform with a plastic or wooden half-sphere attached to the bottom. Depending on the size of the half-sphere, the wobble board can be raised between one-half inch and two inches. A wobble board allows for instability in more than one plane of motion, providing athletes with exercises that more closely reflect field conditions.

• Balance board exercises consist of rocking the balance board back and forth in various directions on a timed basis or for a certain number of repetitions. With some exercises, patients progress from exercising with two feet to a single foot. Those needing further challenge may do the exercises with their eyes closed. Sensors help individuals detect motion that may cause imbalance. Based on that input, commands to correct the imbalance are sent. Then the muscles contract and expand to correct the imbalance. In such a way, both the nervous system and the muscles are exercised.

• Stability ball: Using a stability ball develops coordination between muscles and nerves, according to the American Council on Exercise. They observe that trying to stabilize oneself while exercising with the ball creates overloads that increase muscle strength and joint integrity.

• Foam stability pad: Researchers at Nicholas Institute of Sports Medicine and Athletic Trauma asked high school football players whom they determined to be at risk for ankle sprains to undergo balance training with a foam stability pad. (At-risk players were ones with a high body mass index or previous ankle injury, or both.) Foam stability pads are about 15 by 9 by 2 inches high and are available in several levels of firmness. The athletes were asked to balance five minutes on each leg, five days a week during preseason and two days a week during the football season. The intervention significantly reduced the incidence of injury among high-risk players.

• When using unstable apparatuses, patients should progress to one-legged stances after having mastered the stance with both feet.

• Exercise practitioners recommend that balance exercises be part of a general fitness program that addresses both skill-related and health-related components of fitness. Several experts caution that balance exercises may not represent the particular functional aspects of situations likely to be encountered in an individual's sport or other physical activity.

Theory/Evidence

• Balance exercises address the area between the knees and the toes, improving the strength, mobility, flexibility, and elasticity of the muscles, tendons, and ligaments. Strengthening the muscles of the feet and ankle and strengthening the Achilles tendons help to stabilize and control the foot and lower part of the leg when moving. Strengthening this area is especially important since an individual's ankle has a natural tendency to move inward and rotate when one's foot hits the ground (a phenomenon called "pronation").

• Proprioceptive training in the form of a progressive single-leg dynamic balance exercise may improve dynamic joint stability quickly, in some cases after 2-4 weeks of training, according to research.

• Evidence shows that with a training program that includes progressive degrees of instability on a wobble board, improvements to both static and dynamic balance among healthy adolescents may be seen in six weeks and reduction in sports-related injuries over a six-month period.

• Ankle injuries are the most common sports-related injuries, estimated to be 25% of all injuries across all sports. The acute lateral ankle ligament injury is the most common ankle sprain, accounting for 85%. In the Netherlands between 2000 and 2002, researchers estimate that 120,000 ankle sprains were registered, of which 36% needed medical treatment.

• Research shows that among those with ankle sprains or anterior cruciate ligament (ACL) injuries, proprioceptive training and neuromuscular training (involves both the nervous system and the muscular system) may be effective in both increasing ankle or ACL functioning and decreasing the incidence of reinjury. However, considering postural control, joint-position sense, neuromuscular control, joint laxity, and lower-extremity strength, other research suggests that training may have no effect.

• While research shows that proprioceptive balance training is effective at preventing ankle reinjury, there is a lack of consensus about the role of proprioceptive balance training on the prevention of initial ankle injuries.

• Research shows that injuries may reduce an individual's ability to balance if muscle inhibition occurs in response to a joint injury. Joint injury may cause joint swelling, which in turn may disrupt communication between body sensors and the central nervous system. A consequence of such disrupted communication may be changes to the individual's proprioceptive abilities. For instance, neurosensors attached to tissue will move out of their usual position if the tissue they are attached to swells. Balance problems and postural instability may be the result if these altered relationships in turn lead to neuromuscular inefficiency.

• Balance training for athletes: Physical therapists caution that the benefits of physical therapy tend to be specific to the region being exercised. A given balance exercise will use a specific set of muscles and may not provide benefits beyond mastery of the exercise. For example, a one-leg standing balance exercise (static) may have little effect on an individual's balance while running (dynamic). A physical therapist may enhance exercise routines to add destabilizing elements that are more reflective of the variety of external forces an athlete may encounter in competition.

• Of more concern to athletes might be the results of a literature review that suggests that using instability devices to develop core musculature may, indeed, reduce overall muscular power output as core musculature is enhanced. Unstable devices (balance training) are not recommended for primary exercises for hypertrophy (enlargement of muscle cells) or increasing absolute strength or power, especially when compared to ground-based free weights.

• Balance training for seniors: Studies suggest that reduced muscle function is a main risk factor for falls and hip fractures among senior citizens. Proprioception is important in triggering a response through the neuromuscular system, but muscle function is how individuals regain balance when circumstances cause imbalance. Impaired balance or difficulties with postural control are also risk factors for falls among seniors, as are impaired gait, impaired vision, influence of medications, and impaired cognitive functions.

• Among seniors, specific balance training has been shown to improve postural stability. Balance training may help with correction of body displacement as well as perception of body displacement. In other words, balance training may help remind the body where it is and help make adjustments to keep the body there.

• Ataxia, or a brain-related lack of coordination or lack of steadiness, may be treated with balance training. Researchers found that subjects who underwent foam-pad balance training, incorporating exercises with head extension and closed eyes, showed improved postural sway of up to 50% within five days. The researchers recommend that clinicians use balance training with ataxia patients with a program that includes increasing levels of instability in order to activate sensorimotor rearrangement.

Safety

• A qualified health care provider should be consulted before beginning any new exercise program.

• To avoid soreness and injury, individuals contemplating an increase in physical activity should start out slowly and gradually build up to the desired amount. People with long-lasting health problems, such as heart disease, diabetes, or obesity, or those at high risk of developing these problems should first consult a physician before beginning a new program of physical activity.

• Physical activity may involve large motions that might displace the body's center of gravity, which in turn may threaten an individual's balance. Therefore, individuals should be careful that balance training itself does not lead to falls and injury. Studies have suggested that, among seniors, both the most active and the most inactive may be at high risk of falling during exercise. The risk of exercise-related falls may be reduced by enlisting the supervision of a trained physical therapist and by undertaking the exercise program in a step-wise, progressive fashion.

• Researchers have observed a "cycle of injury," which starts with postural or joint instability. When an individual responds to an injury or other condition with faulty movements or compensates in an exaggerated way, the individual's central nervous system will recruit other muscles to transfer the forces needed for movement. The result of using "new" components of the motion system may lead to increased instability. The term for such a transfer of responsibility is synergistic dominance. The National Academy of Sports Medicine advises that such functional instability resulting from lack of joint stabilization may be addressed by including balance training in the individual's training program.

Author Information

• This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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