Dr. Peraza has been engaged in the research and development of physical therapy/ musculoskeletal devices since 2009. His research interests in Ergonomic and Occupational Medicine studies led to the invention of the ResQUp fall recovery device, recently featured in the Arizona Republic. He is also a Certified Functional Capacity Assessment Specialist and Certified Ergonomic Assessment Specialist through the Back School of Atlanta (2008) and has specialized in Occupational Medicine Physical Therapy since 1997. His work includes performing Functional Capacity Examinations, Ergonomic Assessments, and Job Placement Assessments. Dr. Peraza is an experienced clinician with extensive and detailed work in Healthcare, Body Mechanics, and Ergonomics.
Summary of Clinical Application
In general, a user who has limited volitional strength in the upper body and legs while attempting to ascend from the floor or descend to the floor from a seated position is forced to strain with their hands, wrists, arms, shoulders, neck muscles, and skeletal support regardless of the method or device employed for that purpose. The process necessarily requires gripping, leveraging, and flexing movements under essentially the entire user’s body weight, which puts the user’s arms/shoulders at potential dangerous point of tissue failure.
Considering the case of arms/shoulder alone and the attendant physiological principles, Graphs A and B summarize the relationship of tension (strength) as a function of muscle length. The principles that apply are thus: a muscle fiber responds differently under passive vs. active conditions. When a muscle fiber is passively lengthened, as shown in Graph A, it acts much like a rubber (elastic) band: the more the fiber is lengthened (stretched), the more tension is realized until the point of failure (rupture).
A clinical concern from a Physical Therapist perspective is when a user places shoulders in a passively overly-lengthened and potentially injurious position (that is, towards the right side of the Passive Tension Curve. Thus the muscles are near their failure/maximum exertion points, and the combined active and passive tension increases the likelihood of failure at some point. To reduce the risk of shoulder injury, the ResQUp fall recovery device, patented in February of 2013 has been purposefully designed to keep shoulders in a mid-range position (middle portion of Passive Tension Curve), in particular the distances from the floor to the first levels (4 1/2 “, and from each subsequent level to the next level (4 ½” each), as well as each level’s respective size and dimensions.
When actively stimulated by a motor nerve, a muscle fiber’s ability to generate tension (strength) and its length are closely related as shown in Graph B. When a fiber is placed at or slightly longer than its rest length, maximum tension is realized. If the fiber’s proximal and distal ends are approximated (to the left of the Blix Active Length-Tension Curve) tension production decreases. Similarly, when the fiber’s ends move farther away from each other (i.e., stretched) tension production again decreases (to the right of the Blix Active Length-tension Curve). This curvilinear relationship, originally described by the Swedish physiologist Blix, is known as the Blix Length-Tension Curve. The same relationship holds true for the gross muscle.
At the microanatomical and physiological level of analysis the length-tension relationship may be explained in the context of providing maximal cross-bridging between actin and myosin (i.e., myo-proteins) and therefore sarcomere shortening (i.e., Z-line approximation) and tension production. Maximal cross-bridging results when a muscle fiber is maintained at or close to its rest-length. If the fiber is at other than its rest-length (i.e., too short or too long) cross-bridging will be minimized resulting in less tension production.
The ResQUp is intentionally designed so that shoulder muscle length is near the center of the Active Length-Tension Curve where greatest tension (strength) can be generated. This is a significant physiological design feature of the ResQUp which minimizeshyper-extension of the shoulders and excessive muscle lengthening. Otherwise less active tension (strength) is generated and the shoulder joint is placed in an “end-range” position. This results in the muscles of the shoulder being in a mechanically disadvantaged position that may lead to the increased likelihood of rotator cuff strain or rotator cuff tear.
Further, the user’s wrists can also be placed in an extreme extension position and become another area of the body that is stressed while ascending from the floor and descending to the floor. The ResQUp fall recovery device has additional utility that permits a user to use an “elbow-up” procedure with the ResQUp, which minimizes the use of the wrists. This procedure also makes use of the desired mid-range of active and passive tension that is very near the center point in Graph B.
Another design element of the ResQUp addresses “shear” forces to the skin as a user negotiates from one level to another. Shear results in disruption or angulations of blood vessels (Chronic Wound Care: A Clinical Source for Healthcare Professionals, edited by Diane Krasner RN, MS, CETN) and is a common occurrence when a patient moves up, down, or along any surface. The design of the ResQUp fall recovery device minimizes shear forces by virtue of rounded and contoured leading edges to lessen tissue stress on the ischial tuberosities, sacrum, and buttocks for individuals who have fallen and utilize various means to get up from the floor.
Observation, experimentation, trial, and error during the development of the ResQUp produced a device that provides a safer method for a person to ascend from the floor or descend to the floor when they otherwise couldn’t do so. Using the ResQUp fall recovery device is not only safer for the individual involved, it is also safer for any caregiver/family member/therapist/assistant who assists a person to get up from the floor in particular. The design of the ResQUp puts a user in the position of utilizing mid-range musculature, where they are the strongest, thereby minimizing possible harm to themselves and their caregivers.
The ResQUp enables the use of the musculature and skeletal structure around the optimum range of strength and with a non-extreme point of the muscle’s position. This is true because by enabling a mid-range of arm/shoulder/elbow extension to accomplish movement from the floor to a seated position typically prevents musculature failure, or that point where the person’s muscles give out, causing them to crash to the floor. The ResQUp fall recovery device also helps to minimize muscle tears, joint problems, and other issues caused by overstrain.
The ResQUp delivers a safer and effective device and method for patients or individuals to raise themselves up from the floor while minimizing strain on joints and tissue.