Compensation Strategies in Response to Fatiguing Propulsion in Wheelchair Users

Abstract

Objective The aims of the study were to examine whether fatigue-inducing wheelchair propulsion changes neuromuscular activation and propulsion biomechanics and to determine predictor variables for susceptibility to fatigue. Design This study with a quasi-experimental, one-group, pretest-posttest design investigates a population-based sample of wheelchair users with a spinal cord injury (n = 34, age: 50.8 ± 9.7 yrs, 82% males). Neuromuscular activation and propulsion biomechanics during treadmill propulsion at 25 W and 45 W were assessed before and after a protocol designed to cause fatigue. Results With the induced fatigue, wheelchair users propelled with increased neuromuscular activation in the pectoralis major pars sternalis, deltoideus pars acromialis and upper trapezius (45 W, P < 0.05), and a slightly reduced push angle (25 W: 75–74 degrees, P < 0.05, 45 W: 78–76 degrees, P < 0.05). Wheelchair users susceptible to fatigue (47%) were more likely to have a complete lesion, to be injured at an older age, and had less years since injury. This group propelled in general with shorter push angle and greater maximum resultant force, had a greater anaerobic capacity, and had less neuromuscular activation. Conclusions Compensation strategies in response to fatiguing propulsion could increase the risk for shoulder injury. Predictor variables for susceptibility to fatigue inform interventions preserving shoulder health and include lesion characteristics, propulsion technique, anaerobic capacity, and neuromuscular activation. To Claim CME Credits Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME Objectives Upon completion of this article, the reader should be able to: (1) Explain a neuromuscular compensation strategy and the corresponding muscles in response to fatiguing wheelchair propulsion; (2) Recommend propulsion biomechanics associated to reduced susceptibly to fatiguing wheelchair propulsion; and (3) List examples of predictor variables of susceptibility to fatigue. Level Advanced. Accreditation The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The Association of Academic Physiatrists designates this journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Changes in supraspinatus and biceps tendon thickness: influence of fatiguing propulsion in wheelchair users with spinal cord injury

“…This dichotomization has been used previously and was found to be capable of identifying persons who display more changes in neuromuscular activation associated to fatigue after the Figure-8 protocol in the same study population. 9 Tendon appearance-The region of interest (ROI) of each ultrasound image was defined from the interference pattern at the top of the images, created from the steel reference markers attached to the skin throughout the protocol (Figure 2). From the ROI, tendon characteristics including tendon width (mean distance between top and bottom border of the tendon), echogenicity ratio (mean pixel grayscale of tendon divided by mean pixel grayscale of muscle above tendon) and a co-occurrence matrix-derived measure contrast (intensity difference between a pixel and its neighbor in the vertical direction which is perpendicular to expected direction of the collagen fibers) were calculated.…”

“…In-depth detail on the recruitment and study procedures has been reported previously and is briefly described below. 9 This publication is part of a bigger project that aims to determine the effect of fatiguing wheelchair propulsion on risk factors for shoulder pain in persons with SCI. Compensation strategies in neuromuscular activation and propulsion biomechanics in response to fatiguing propulsion have been reported previously 9 , the current publication describes the ultrasound results which have not been presented elsewhere.…”

“…9 This publication is part of a bigger project that aims to determine the effect of fatiguing wheelchair propulsion on risk factors for shoulder pain in persons with SCI. Compensation strategies in neuromuscular activation and propulsion biomechanics in response to fatiguing propulsion have been reported previously 9 , the current publication describes the ultrasound results which have not been presented elsewhere. The pre-intervention ultrasound exam took place before any kind of propulsion activity, while the post-intervention ultrasound exam took place following the completion of all propulsion tasks.…”

“…Additional propulsion tasks, of which results have been published previously, in between the pre -and post intervention include two times 40 seconds (s) treadmill propulsion at 1.11 meters/s at 25 Watt and 45 Watt, three maximum push tests and a maximum 15 meter overground sprint. 9…”

“…6 Furthermore, the supraspinatus tendon is subject to high relative loads and was found to be prone to fatigue during wheelchair propulsion. 1,7 Fatigue (i.e., a status of limited functioning by interactions between performance fatigability and perceived fatigability 8 ), resulting from repetitive wheelchair propulsion 9 , may play a role in the development of tendon degeneration and pain.…”