Part I – The Model
The Personal Transfer Model describes wheelchair transfers as the combination of three personal factors of:
· Strength – The amount of mechanical ability of the person to willingly move parts of his or her body as desired.
· Flexibility – The degree of passive body positioning available in the person’s body.
· Technique – The level of technical ability of the person to move his or her body.
Where strength is not just a measure of muscle capacity. It also includes considering the muscles that are available for use. A person with a high level of spinal cord injury has fewer muscles to draw upon then a person with a low level of spinal cord injury. Therefore, he or she has a lessor amount of strength. The presence or absence of pain effects the amount of strength available.
Where flexibility takes into consideration the presence or absence of muscle spasms as well as joint mobility. A person with spasms is less flexible than a person without spasms.
Where technique is a measure of inherent and learned body movement. It is made up of acquired skill and also the person’s ability to effectively move his/her body as desired in terms of coordination, speed, and accuracy of positioning.
The three Personal factors are interconnected with the specifics of the Device(s) involved and also the surrounding Environment. (See the Personal Mobility Model for more details about this relationship). Transfers are dependent on both the physical characteristics of the device the person is transferring from or into, and also that of the environment he or she is currently in.
For example, the setup of a person’s wheelchair will have an influence on whether they choose a Sideways, Front, or Rear method of Floor-to-WC transfer. Wheelchair factors include the width of the seat and footplate, the forward and rear stability of the wheelchair, the presence or absence of brakes and arm rests, and more.
Environmental factors include the immediate surface conditions such as slippery, wet, dry, firm, soft, inclined, etc. along with the availability of props that could be used for mechanical advantage and assistance. The environment also includes the presence or absence of people who are able to assist with the transfer.
A transfer is the result of all of these multiple factors taken into consideration. A person who is lacking in one or more areas needs make up the difference in the other area(s). For personal factors, a person who lacks strength needs to make up the difference with flexibility and/or technique. A strong person may need less technique and/or flexibility. A person with great technique may be able to get by with less strength and/or flexibility.
A “friendly” environment reduces the need for personal factors. Whereas a “hostile” environment increases them. Some wheelchairs (devices) are inherently easier to transfer in and out of then others.
The immediate goal of a transfer is to create a successful outcome in a safe manner. The result of transfer training should be to increase the person’s ability to repeatedly create successful outcomes while also minimizing risk. Depending upon the individual, one or more of the components of the Personal Transfer Model should be the focus of his/her training to create the greatest impact.
The least understood component of the Model is Technique. Technique is the application or expression of certain physical concepts. Every person will apply the concepts in a different manner, but the underlying dynamics don’t change.
I have outlined multiple movement concepts (S-Concepts) involved in bodily transfers. Understanding how these concepts work and can be utilized is key to creating effective transfer technique.
1. Swing – A person who uses his (or her) arms to transfer creates a swing where his arms are the supports, and his Center of Mass is the seat. A swing can move forward and back between its supports and also from side to side with the application of force. It can travel in an arc. The force of gravity pulls it to the middle of the supports. Therefore, gravity must be overcome to bring the person completely from one side to the other.
For example, when transferring from a wheelchair to another seat, the Leading Hand (forward support) rests on the target seat while the Trailing Hand (rear support) rests on the person’s wheelchair. The person’s butt/hips (Center of Mass more or less) is forced to move laterally along the line or arc created by the two hands.
2. See-Saw – The person’s arms and upper torso create the fulcrum. The surface or structure that her hands rest upon or grip form the base of the fulcrum. And the person’s head and lower body form the opposing sides of the See-Saw (levers). When one side goes down, the other side tends to go up (a body is not a stiff board, but the lever principal still applies).
For example, assume a transfer from a wheelchair to a higher seat. In this case, the transfer follows the same procedure as described above, but the person’s butt must also raise to a higher elevation. By leaning forward and dropping down with her upper body (See), she will reduce the force required to raise her butt higher (Saw).
Generally speaking, wheelchair transfers involve moving the person’s Center of Mass (butt/hips) from one stable position to another. Once the butt/hips are properly situated, the other body parts can be then moved to their desired position.
3. Sit n’ Spin – Some transfers involve an arcing pivot movement. There are times when the person’s feet and legs form the axis of this rotational movement. While his legs may (or may not) bear the weight of his body, having them resting on the ground reduces the total body weight that will have to be transferred. As the transfer occurs, his feet will rotate on an axis. On most surfaces, minimal friction is created, but significant weight can be reduced.
Another example is when the person is sitting on the ground with her knees pulled in tight to her chest with an arm. She uses her other arm to generate a spin allowing her to face another direction in order to initiate the transfer.
4. Slide – When dealing with a smooth continuous surface, it may be easier for a person to slide his body along the surface as opposed to lifting it up, over, and down. A slide board takes advantage this concept and can be used to create a physical bridge between the person’s wheelchair and the target location. Another example is when a wheelchair user scoots (slides) her body forward to the front of her wheelchair. This change in location reduces the distance of the subsequent transfer.
5. Structure – Effective wheelchair transfers take advantage of the person’s skeleton to create stability, support, and positioning even if his or her muscles are not actively being engaged or are weak. The concept is to align the bones in such a manner that they either support the body or influence its movement/ positioning as desired. For example, assuming sufficient flexibility, many wheelchair users are able to squat with the majority of weight supported by the legs and feet without using any lower body muscles. This position can be used as part of a transfer.
This concept includes situating the body to provide the greatest mechanical advantage, balance, and least amount of stress on muscles, tendons, and joints. For example, arms that are spaced shoulder width apart create the most effective positioning for both pulling straight up (pull-ups) and pushing straight down (dips). Arms that are either too close together or too far apart increase the difficulty of the transfer.
6. Shifting and Switching – Shifting involves distributing weight from one supporting limb to the other, typically an arm. For example, shifting body weight from the Trailing Hand to the Leading Hand. A Switch is change in position of a supporting limb while it is still carrying weight. Therefore, switching is a coordinated movement that effects balance. One example is “walking/hopping” the Trailing Hand forward during a Floor-to-WC transfer to reposition it while still holding up the person’s body.
7. Spring – A Spring is an explosive movement that uses muscular power and momentum to execute a transfer. Typically, the transfer is completed in a singular fluid movement. The Spring is like a jump in that the body is first coiled (or stretched) then rapidly reversed to generate the motion.
8. Screw – This movement is generated by the person’s truck and/or lower body. It involves a twisting of the waist which enables a person to switch from forward to backward facing or vice-versa. It is typically done when the person’s arms are supporting his/her body weight and are not able to generate sufficient turning motion.
9. Setup – The setup is the first stage of the transfer where the person positions his or her body, particularly lower body, in the optimum position to execute the transfer. Initial body position is very important because it may be difficult (or impossible) to adjust body position mid-transfer. 10. Stability – Transfers depend upon using muscular force to get from one position to another. This force is maximized when generated from a stable base. Force is lost when the base is unstable. Therefore, it is important to consider the stability of the object you are using to push off or pull from. For example, wheelchair parking brakes are the most common method of creating wheelchair stability.
11. Slipping – Slipping is a potentially dangerous event. When people slip, they are likely to fall. Transfers that use lower body Structure need to take into consideration the possibility of unintended and unwanted foot movement. Therefore, foot traction should be a consideration when determining a transfer method. For example, a wet bathroom floor combined with bare feet increase the likelihood of a foot slip. Water also increases the likelihood of one of the person’s supporting limbs slipping from its holding position resulting in a fall.
12. Stretch – Stretch is part of the execution of flexibility. Frequently, a person will need to stretch (or reach far out) his or her limbs in order to place them in the proper position for facilitating a transfer. Often the difference between a successful transfer and failure comes down to a few inches of bodily movement. Therefore, having the ability to stretch one’s body is an important aspect of making a transfer. Some people may need to stretch before making a transfer. Some may need to trigger spasticity before executing the transfer so that the spasms do not occur during the transfer.
13. Spasticity – The presence of spasticity is a major consideration for transferring. While a minority of people are able to trigger muscle spasms which provide a useful function, most find the muscle contractions to be debilitating. These contractions work against the person’s flexibility both before and during the transfer. Many people with severe spasticity have difficulty stretching. As a result, they have excessive muscle tone which inhibits their flexibility even if a spasm is not triggered.
14. Stages and Steps – While some transfers can be made in a single movement, others require multiple distinct sections to complete. The overall transfer is broken down into multiple time stages, where each stage may also be a transfer. Using stages allows a large transfer to be broken down into more manageable small parts.
Typically, the most difficult part of a transfer comes from gaining or losing height due to the pull of gravity. Steps are physical mechanisms such as landings that allow for going up or down once stage at a time.
15. Stress and Strain – When making a transfer, the use of muscles will naturally stress them. Stress is not inherently detrimental, but strain is the application of excessive stress to muscles and joints which may cause injury and should be avoided.
16. Stoppage – A stoppage is an event that will cause the transfer to fail, possibly mid-transfer. It is important to identify potential sources of stoppages before executing a transfer in order to minimize the risk of them occurring. A triggered muscular spasm may create a stoppage. Sudden muscle failure is another source of failed transfers. In this case, the muscle is overtaxed and gives out resulting in a missed transfer.
17. Simplicity – The simpler a transfer is, the less likely something will cause it to fail. In addition, it is likely to be faster to execute. Therefore, the goal of transfer simplicity is to eliminate unneeded actions or movements.
18. Style – A transfer is not a completely utilitarian event. People care about how they are perceived by others. Most want to be (or appear to be) as independent as possible. Therefore, the details of exactly how a person transfers may need to be considered. Some transfers are particularly awkward looking. Others less so. Preferred transfer methods depend upon the preferences and capabilities of the individual.
19. Situational – Every individual transfer is dependent upon multiple circumstantial factors that are subject to change due to varying environment and personal factors.
20. Systemic – There are certain commonalities to transfers that are universal (Systemic) considerations as noted by the S-Concepts.
21. Skills – Transfers are complex motor functions. Some are more complex than others. As with all skills, they require effective training to execute well. Some people take longer to learn skills than others. In order to learn (or teach) transfers, it is important to approach them as skill training as opposed to only thinking them in terms of medical rehabilitation.
The twin ultimate goals of transfer training are to make personal transfers as easy as possible and to expand the universe of transfers that can be successfully made. The Personal Transfer S-Concepts are a means to accomplish these goals. They are the underlying concepts that make up successful transfer techniques and considerations. Different people will use differing techniques in accordance with their Flexibility and Strength as previously noted, but the transfer concepts are universal.