The Development of Limb Accelerations as a Measure of Neuromuscular Impairment and Predictor of Ambulatory Ability Following Spinal Cord Injury

After a spinal cord injury (SCI), clinicians must quickly decide if they want to focus therapy towards gait training or wheeled mobility interventions to maximize an individual's functional mobility by discharge. Clinical prediction rules (CPRs) such as those that use age, strength, and sensation, can assist clinicians in making those difficult decisions, but for individuals with an incomplete SCI, these CPRs are often inaccurate. Additionally, these models only predict whether an individual can walk a short distance without physical assistance, which is not a sufficient description of functional ambulation. Limb accelerations (LA), captured unobtrusively and at a low cost from wearable accelerometers, may provide a responsive and informative movement biomarker of neuromuscular impairment that can be used to determine more accurate predictions of ambulatory ability among those who would benefit from them the most. Our long-term goal is to build a new CPR using LA that predicts functional ambulation after SCI, thus enabling appropriately targeted mobility training. As a first step towards this goal, we utilized a cross-sectional study to build a foundational knowledge of LA and its relationship to measures of neuromuscular impairment (Aim 1) and ambulatory ability (Aim 2) using machine learning techniques and a sample with chronic, motor incomplete SCI and known, diverse functional abilities. Using a longitudinal study consisting of individuals with acute, incomplete SCI, we established that LA is reliable when measured acutely at admission to inpatient rehabilitation (Aim 3a). We also investigated the changes in LA over time (Aim 3b) and in relation to clinical measures (Aim 4a) and explored the potential utility of LA measured at admission to inpatient rehabilitation to predict long-term ambulatory ability (Aim 4b) for those with acute, incomplete SCI. These results demonstrated that LA is a reliable and clinically-relevant metric that is likely to improve the prediction of ambulatory ability, thus improving long-term, functional outcomes for individuals with SCI

Compensation strategies in response to fatiguing propulsion in wheelchair users : implications for shoulder injury risk

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