Friday, May 24, 2019
Shoulder Prevention Part 2: The Shoulder During Manual Wheelchair Propulsion
What happens when an individual propels a manual wheelchair? What muscles are being activated? Does it change across the lifespan? We will not cover this entire topic today but let’s begin with what is happening with the shoulder during manual wheelchair propulsion.
The first question we have to ask is WHY? Why are we even talking about the shoulder during manual wheelchair propulsion?
Because the number of individuals who are full-time manual wheelchair users who will develop shoulder dysfunction and/or pain at some point in their life is staggering. There is up to a 73% reported incidence of repetitive strain injury among full-time manual wheelchair propellers, with the shoulder being the most commonly reported site. It is important for everyone, no matter if you are the therapist, carer, family, end-user, or supplier, to come together to provide the optimal equipment and outcome for the end-user to decrease their risk of shoulder dysfunction.
Starting at the very beginning, is understanding propulsion. Propulsion can be broken down into two phases: push phase and recovery phase. In the photo below you can see the two phases highlighted. The push phase first begins when the hand contacts the push rim and continues until the hand is released from the push rim. The recovery phase occurs when the hand is first released until the hand makes first contact again with the push rim.
These are the two phases, but how the individual moves through these two phases can vary. Below is a photo showing a few different types of propulsion techniques. These techniques may be confusing to look at in a photo, so you can also click this link to watch a video discussing the optimal push technique. This optimal technique, called the semi-circular technique, is discussed in the PVA clinical practice guideline for shoulder preservation referenced at the end. We will discuss propulsion technique further in the next blogs, but for today we will go back to the two phases of propulsion. During each phase, different muscles will be required or activated.
There are many studies looking into the activation of muscles during propulsion. This research can be challenging due to the inherent number of variables with testing. For today, we will look at a study by Mulroy and colleagues from 2004. This study looked at individuals with spinal cord injuries and found the following muscles were activated during each phase:
Anterior Deltoid, Pectoralis Major, Supraspinatus, Infraspinatus, Serratus Anterior, and Biceps
Middle and Posterior Deltoid, Supraspinatus, Subscapularis, Middle Trapezius, and Triceps
Look at the number of muscles involved in propulsion! What as a therapist, or end-user, are we doing to protect and strengthen the shoulder? We want to be sure that we are addressing the shoulder from the beginning whether this is through stretching, strengthening, positioning, modifications or education. This will vary for each individual based on their pain level, diagnosis, strength of each muscle, etc… It is best to have an individual program designed by a therapist to ensure that the end-user is safe.
Next week, we will continue to discuss the shoulder and manual wheelchair propulsion, propulsion technique, and look at some of the ways our end-users are taking care of their shoulders!