Rehabilitation is a rapidly morphing service profession as it responds with new technological advances to the rapidly expanding understanding of how people move and how to restore movement.

Therapists are challenged to measure functional outcomes, develop evidenced-based therapeutic interventions, and reach the rehabilitation potential of each patient with fewer sessions. No longer can we "work at it until we succeed." Therapists must now provide research-supported paradigm systems behind their treatment plans. The expectation is that the therapist can design the most effective and least expensive treatment plan to meet the unique needs of each patient.

As with any business, our success rate is measured for each patient that we take on. We must select the optimal method and treatment plan, and prove we have reached treatment goals within insurance compliance and on time authorized treatment sessions.

There is a plethora of tools available with which the PT can construct a treatment plan. The most recognized program in both the world of rehabilitation and fitness is that of core stabilization. At the heart of the core-stabilization industry, there is a recognized need for the body to enable proximal stabilization systems to provide the automatic, primary, protective postural response before movement that reduces perturbation of the body's center of gravity before and during the execution of the task.

The postural, protective response by the body to ready the trunk for use of the extremities comprises scapular, pelvic, and spinal elements. Such a distinction is seldom made, because pelvic and spinal stabilization can be seen as inseparable and, until now, few specific tools for scapular stability have been available. With the MARV™ handle, scapular stabilization can be isolated or done in conjunction with pelvic and spinal core training. Core-stabilization tools challenge that protective, postural "set" response of the body to restrict the proximal skeletal motion for the most efficient distal muscle function. The large gym ball is probably the most recognized stability tool in the world, yet it offers much more for pelvic or spinal core stability than scapular.

Most strengthening exercise for the upper extremity is dependent upon handles and weights, all held in the hand. These tools allow the therapist to limit exercise by placing the patient's lower body in a constrained position or to facilitate a total postural response by having the patient stand while exercise machines are designed to isolate muscle groups. When a patient holds a pulley, dumbbell, or elastic tubing in the hand, the length of the patient's arm determines the degree of stability difficulty. Exercise programs initially were designed purely on principles of biomechanics. Until the MARV handle, patients with upper-extremity limitations did not have the choices in altering the stability component of the exercise-program designs that are now available. Having the opportunity to study many different exercise programs over the last 2 decades with surface electromyography (sEMG), I was most impressed by the response subjects had to the addition of the MARV handle into simple resistance exercises.

STUDY SPECIFICS

Table 1 Muscles monitored during biceps curl.

Forearm Wrist Extensors Biceps Brachii Pectoralis Major Anterior Deltoid Infraspinatus Middle Trapezius Lower Trapezius Brachioradialis

Figure 1. Lever arm differences

A small pilot study was designed to examine the MARV handle. The exercise chosen was a simple biceps curl to limit the variables created by a multiple joint task. The muscles monitored with surface electromyography (sEMG) are shown in Table 1. The study was designed so that the demand moment of a biceps curl when done with a standard pulley handle and then repeated with the MARV handle (with its patented channel grip) would be identical. If there were no biomechanical differences, the perceived exertion would be the same. However, the biomechanical difference provided by the MARV handle is that there is an increase in the length of the lever arm, as shown in Figure 1. Point A to point B represents the length of the lever arm with a standard handle, while the distance from point A to point C shows the increased length of the lever arm with the MARV handle. With a standard handle, the biomechanical force is calculated from the palmar crease where the handle is held. With the MARV handle, the biomechanical force is exerted 5 inches farther distal to the palmar crease where the cord exits the channel in the handle.

Three healthy subjects were used for this pilot study. Each participant completed an informed consent and a questionnaire that determined they had no prior injury to the dominant upper extremity that would disqualify them and that they each participated in some form of exercise but were not elite athletes. Each subject lifted 15 pounds with the standard pulley handle. The weight lifted with the MARV handle was determined so that the demand moment was constant in both tasks. This resulted in a weight reduction with the MARV handle to approximately 10 pounds for each subject due to the addition of 5 inches in the lever arm. The subject was seated so that the pulley rope came up from the floor, perpendicular to the forearm when the subject was seated with the elbow at 90º of flexion and the humerus was also perpendicular to the floor. To reduce vast changes in the demand moment if the elbow moved through its full range of motion, each subject was limited to 20º of movement—from 100º to 80º of elbow flexion/extension. Six repetitions were performed with each handle at a constant speed, and 3 minutes of rest was required between the two tasks for physiological recovery.

Figure 2. The MARV handle.

The peak amplitudes for each subject's six repetitions and eight muscle sites are provided at the following Web site: www.marvtec.com. What is striking in examining the peak amplitudes is that all of the maximum values occurred while using the MARV handle with very few exceptions. While the exercise, by design, was to focus on the use of the biceps to perform elbow flexion, there was a significant difference in how all subjects responded to the two different handles. All subjects reported that their perceived exertion was significantly greater with the MARV handle even though they were lifting 5 pounds less weight. There was a general increase in use of the forearm extensor group and the brachioradialis with the MARV handle. This is due to the need to hold the handle in the proper position, to keep the cable in the channel grip, and, most importantly, to adapt to the increase in lever arm at the distal end.

The response to the use of the MARV handle was a "spreading" of the effort exerted to other muscles, whether the biceps itself increased in amplitude or decreased. Such a response is totally appropriate to a task that lengthens the lever arm, making it more difficult and requiring a greater stabilization effort. The maximum peak amplitude for each muscle was then compared to the peak amplitude of each of the 12 repetitions. This represents the percent of the maximum effort of each muscle and allows comparison of how that muscle performed with the two different task variations. This data, as well as the sEMG graphs of each task, are also available at the Web site. Overall, there was a general increase in overall amplitude recruitment of about 30% when the MARV pulley handle was used with an equal demand moment.

TREATMENT OPTIONS

The MARV handle demonstrates several critical principles of exercise and the choices that therapists should make in designing such programs. Virtually all other upper-extremity equipment puts the end of the lever arm inside the hand's grip, but this does not represent the lever arm of many functional activities of daily living (ADL) and functional tasks.

The MARV handle can duplicate many functional challenges with simplicity. In the last decade, as the emphasis has increased to provide functional exercise and outcomes, therapists were often left without the necessary tools to provide functional challenges for shoulder and scapular strengthening. It is common that functional activities of the upper extremity do not place the center of gravity within the palm, but rather further distal, increasing the joint segments needing stability. As with many ADL and work-related tasks, the upper extremity requires that scapular stabilization be provided with the addition of spinal and pelvic stability for many tasks.

The MARV handle provides an exercise format that more closely resembles the functional challenges our patients face every day, from lifting a gallon milk jug to holding a pair of pliers. Duplicating numerous ADL tasks within the exercise program provides not only a better long-term outcome to therapy but also a lower risk of further injury.

In the face of the alarming rise in costs for repetitive strain injuries of the upper extremity, the MARV handle may provide therapists with an important advantage in program design. Many employees have job tasks with extended lever arms by nature of tools, such as pliers and screwdrivers, or task-related tools, such as food-handler trays, boxes and even the tiny tools of fine assembly work. In the assembly of tiny computer board components, for example, the tools may be small in design with many enhanced ergonomic advantages in the last decade, but they still put the force required to complete the task beyond the palmar crease, thereby requiring greater multijoint stabilization. Even the typist exerts the force through the fingertips, requiring an exercise program that reflects these needs.

The focus in recent years has emphasized the influence of motor control on muscle recruitment during exercise. One cannot strengthen a muscle that does not fire, and biomechanics can be used to facilitate the activation of such muscles. The motor-control component of how a patient responds to exercise cannot be forgotten. But we know that strength gained in exercise is very task-specific, and so the ability to reproduce more functional tasks with the addition of the MARV handle must be considered in designing exercise programs.

The MARV handle can be incorporated into an exercise program at any level of exercise from the most gentle to the most aggressive. With the MARV handle, the same principles of facilitation that have been developed for the lower extremity to facilitate pelvic and trunk control are now available for the scapula. By incorporating the simple principles offered by the MARV handle into exercise at the clinic, at the gym, and at home, scapular stability would be much better prepared for the repetitive or sudden-load demands that are imposed through the upper extremities of our patients.

Barbara J Headley, MSc, PT, received her bachelor's and master's degrees in physical therapy and has been practicing for 38 years. Headley has dedicated the last 23 years to the study of movement and soft-tissue dysfunction using surface electromyography. In addition to consulting, performing clinical research, writing, and lecturing, Headley owns Innovative Systems for Rehabilitation, Bloomfield Hills, Mich. She can be reached at www.barbaraheadley.com.