The Range of Motion

Cost-effectiveness has become a buzzword in health care today, with professionals searching for less expensive modes of treatment. In addition to the recent decreases in health care reimbursement, insurance companies have limited the number of therapy sessions, leading to an increased reliance on patients performing exercises at home. For many years, physical and occupational therapists have prescribed home exercise programs (HEP) for their rehabilitation patients. In addition to being cost-effective, HEP's also empower the patient to become responsible for his or her rehabilitation--hopefully leading to a lifestyle including regular exercise.

Several factors are involved in prescribing an effective HEP. Ultimately, for the HEP to be effective, the patient must be compliant and perform the exercises as prescribed. But first, the therapist must be an effective teacher and prescribe the appropriate home exercise program. The therapist must choose the appropriate number and type of exercises specific to each patient's individual problems and needs. The type of home exercise equipment also is an important consideration. Home exercise products should have similar characteristics: portable, safe, convenient, inexpensive and easy to use.

The Science of Elastic Resistive Exercise

One of the most commonly prescribed home exercise products is elastic resistance bands or tubing. Elastic resistive products are typically offered in progressive levels of resistance denoted by different colors. Each color of band corresponds to a specific amount of force production. As the band is stretched, the resistive force increases linearly (See Figure 1). Regardless of the initial resting length of the band, the force production will be the same at similar elongations In a specific brand and color, for example, a one-foot piece of band stretched to two-feet (100 percent elongation) will produce as much force as a two foot piece stretched to four feet (100 percent elongation). Force-elongation charts are used to determine the resistance of each color band for a particular brand of elastic resistance (See Table 1). There is approximately a 20 percent to 30 percent increase in resistance levels between colors for Thera-Band® resistive bands

A common misconception is that elastic resistance may not match the natural strength curve or torque of the joints. As the range of motion of a joint increases toward end range, the muscles become shorter and reach their weakest part of the range of motion. This ending range of motion often corresponds with the point where the elastic resistance is at its maximum tension. Many have mistakenly confused force of the resistive band or tubing with torque, the interaction of the resistance and the lever arm. Recent research has demonstrated that with proper patient positioning, the strength curve of elastic resistance is similar to human joints, producing the typical "bell-shaped" strength curve (Figure 2). In fact, Hughes and colleagues in the Journal of Orthopedic Sports and Physical Therapy, demonstrated that the strength curves of elastic resistance were very similar to those of isotonic dumbbells when performing a shoulder abduction exercise.

When compared to other modes of resistance exercise, elastic resistance offers several benefits. Isometric exercise is effective at strengthening, but only at the specific angles trained. Isotonic exercise relies on gravity for resistance, thus limiting the number of exercises and requiring heavy equipment. Isokinetic exercise is effective, but also is expensive and less portable than elastic bands or tubing. Elastic resistance offers progressive levels of resistive exercise that can be used in any plane of motion, throughout a full range of motion. Finally, elastic resistance offers all types of muscular contraction including, concentric, eccentric, isometric, and plyometric exercises.

Prescribing Elastic Resistance Home Exercise Programs

When prescribing home exercise programs, it is important to demonstrate the exercises in the clinic first, and occasionally have the patient perform them in front of the therapist to ensure proper form. Obviously, the most important factor is the exercises themselves. Other factors to consider are patient positioning, proper band selection and progression of exercise.

Patient Positioning

When prescribing elastic resistive exercise for home programs, the importance of proper positioning of the patient cannot be over-emphasized. Patients should be thoroughly instructed in the proper body position for all prescribed exercises. Improper placement of the resistive band or the patient may result in unnecessary or unwanted stresses to the joint. Important factors to consider include the origin of the band, the length of the band, and the range of motion performed. It also is helpful to point out common faults or compensations for the patient to be aware of at home.

Proper Band Selection

As previously stated, the color of band denotes a specific resistance level. Dosage of adequate resistance is necessary to provide the appropriate muscular stimulus: too little resistance will not stimulate muscular strength, while too much may cause tissue damage or compensated movement patterns. The resistive level of the band should allow the patient to perform a specific number of repetitions (typically 10-15 repetitions) correctly. This is called a repetition maximum approach to resistive intensity, where the strength capacity of the patient is matched with the appropriate amount of resistance. If the patient cannot perform the prescribed repetitions correctly, the next lowest resistive color should be used; conversely, if the patient performs more repetitions than prescribed, the next higher resistive color should be used.

Progression of Exercise

Muscles only increase in strength when the "progressive resistive exercise" (PRE) principle is followed. Gradual increases in the resistance level are necessary for strength gains to occur. While some have advocated simply shortening-up on the band or grasping the band closer to the origin to increase resistance, this ultimately changes the biomechanics of the exercise, potentially causing unwanted forces on the joint. Exercises using elastic resistance should be progressed simply by performing them with the next highest color level of resistance.

Other Applications of Elastic Resistance

In addition to strengthening exercise, elastic resistance has several other possible applications for home exercise programs. For example, elastic resistance can be used to increase range of motion and flexibility when used as an assistive device for stretching. Elastic resistance also can be used to improve balance--particularly in older adults--by strengthening the lower extremities and challenging postural stability.

Precautions

Safety is an important consideration when prescribing an exercise. The most obvious precautions to take using elastic resistance involve breakage prevention. First, secure attachment to door anchors and exercise handles are suggested to avoid potential loosening or tearing at these points. In addition to the security of the connections, the elastic bands and tubing themselves should be inspected prior to use for any signs of wear including fraying, cracks, tears, or holes. Exercises should not involve elongations


It is important for clinicians to understand the basic science behind the product in order to make an appropriate exercise prescription.
beyond 4 times the resting length of the material (300 percent elongation). Finally, patients also should avoid wearing jewelry or long fingernails when grasping elastic bands to prevent breakage.

Latex allergies are a consideration when using elastic resistive exercise. Health care workers, persons with spina bifida and others with sensitivity to latex proteins and products should not use latex exercise bands or tubing. Latex-free exercise bands now are available for those with allergies to latex.

Reimbursement

Exercise bands and tubing are billed under the CPT code, 99070, Miscellaneous Supplies or the HCPCS II code, A9300, Exercise Equipment. Reimbursement varies by carrier and is usually based on medical necessity. Medicare does not reimburse directly for exercise equipment; however, due to the low cost of elastic resistance bands, patients often pay out of pocket for these items.

In summary, elastic resistive bands and tubing are cost-effective and clinically proven home exercise devices. It is important for clinicians to understand the basic science behind the product in order to make an appropriate exercise prescription. Force-elongation and strength curve characteristics should be considered when prescribing elastic resistive exercise because of their relationship to patient positioning, proper band selection and proper progression. Elastic resistance also can be used at home for improving flexibility, range of motion and balance. When used appropriately, elastic resistance bands and tubing are versatile, safe and effective home exercise products.

This article originally appeared in the January 2002 issue of HME Business.

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