Cardiovascular Health and Fitness
Accumulating evidence supports the important role of pediatric cardiovascular (CVS) health in CVS health throughout life (Umer et al. 2017; Urbina et al. 2019; Wright et al. 2001). The accumulation of behavioral and clinical risk factors that will later influence adult CVS health could be substantially accentuated in children with SCI/D-related paralysis, because, as shown in previous studies, different measures of physical performance, like strength, walking speed, and balance, can act as markers of current and future health in adults (Cooper et al. 2011). Growing and living with paralysis can influence numerous factors that, in turn, could impact lifelong CVS and metabolic health: 1) biological factors: inflammation, gut microbiome, levels of total cholesterol, blood pressure, and fasting glucose; 2) behavioral factors: activity/exercise level, diet and healthy weight/BMI, smoking (including marijuana), sleep, social isolation/bullying, participation, electronic media usage; and 3) economic factors: socioeconomic status, access to care, transition to adult care.
It is suspected that individuals with childhood-onset SCI/D paralysis may fair worse as it pertains to CVS health lifelong. As CVS disease is number one cause of morbidity and mortality in adults living with chronic paralysis (Whiteneck et al. 1992) and the prevalence rate of symptomatic CVS disease is higher in individuals with paralysis than in able body individuals (Myers et al. 2007). While there is no concrete evidence that individuals with childhood-onset paralysis have higher CVS morbidity and mortality than those with adult-onset of paralysis, they do have a 31% increase in the annual odds of dying compared with persons injured at older ages (Shavelle et al. 2007). Thus, assessing and improving CVS fitness in children with paralysis appears quite essential amidst the confluence of multiple inter-relating biological, interpersonal, and behavioral features of this life stage.
Evidence to guide optimal care is quite limited in pediatric medicine and even more so in the relatively small field of SCI/D-related paralysis.
This section reviews evidence examining the following CVS factors:
- Body composition (as assessed by Dual X-ray Absorptiometry), specifically total lean mass, fat mass, percentage body fat, and BMC/BMD
- Anthropometric measures, like weight, height, and BMI
- Measures of metabolic efficiency meant to assess metabolic syndrome likelihood, like fasting lipids, fasting glucose, insulin resistance, resting metabolic rate
- Measures of cardio-respiratory function: resting heart rate, VO2
- Measures of functional performance, like muscle strength, power output, forced vital capacity
Discussion
Seven papers related to CVS health in children with SCI/D-related paralysis were identified. Of the seven, four were observational studies, consisting of anthropometric measurements in cohorts of children that included those with traumatic and non-traumatic paralysis, specifically spina bifida (Liusuwan et al. 2007; Nelson et al. 2007; Widman et al. 2007); Liusuwan et al. (2007) and Widman et al. (2007) also included age and sex-matched able-bodied controls and obese able-bodied cohorts. (Liusuwan et al. 2004) compared SCI with age and sex-matched able-bodied controls.
Three of the papers described findings from the same randomized controlled study of 30 children with traumatic and nontraumatic SCI undergoing either FES-assisted lower extremity ergometry, passive lower extremity cycling, or no cycling electrical stimulation (Johnston, Smith, Betz, et al. 2008; Johnston, Smith, et al. 2009; Johnston, Smith, et al. 2008b).
Children with SCI were found to have higher fat mass and fat %, lower total lean mass, lower BMI, and higher rate of metabolic syndrome. Calculated BMI was found to underestimate body fat in children with SCI. Resting metabolic rate and energy consumption was found to be similar with controls when adjusted for muscle mass. Obesity was not consistently defined, with cut-off ranging 25-30% in males and 30-35% in females in different cohorts. Metabolic syndrome was more common in children with paralysis. Exercise was not found to significantly affect cardio-vascular or metabolic factors. FES-assisted lower limbs ergometry induced a statistically significant change in measure VO2, especially in the children with less neurologic involvement (lower thoracic and lumbar paralysis), but no significant difference in objective pre-post intervention values was noted. Muscle mass, volume, and strength were found to increase with FES, but exercise’s effect on lipid profile was, at the most, partial, limited, and inconsistent. It does appear that response to exercise in pediatric SCI is influenced by injury level, same as in adults.
The only interventional randomized controlled trial was limited by lack of true controls, as all three arms received some sort of exercise intervention (Johnston, Smith, et al. 2009). In addition, normative data for cardio-metabolic parameters were obtained from able-body children and adults with SCI. What the study did show was good adherence with the exercise protocol when the study is done in a home environment.
It is apparent from all controlled cohorts that, in children with SCI/D-related paralysis, physical inactivity and muscle loss are driving factors in the onset of cardio-metabolic complications. In addition, paralysis onset appears to create enduring vulnerabilities that influence the trajectory of cardiovascular health in this population.
Similar to the adult population (Weil et al. 2002), obesity is more prevalent in children with SCI/D-related paralysis and further studies are needed to assess if this is related to unhealthy diet, decreased physical activity patterns, and compounded by genetic, psychological, health behaviors (cigarette smoking, sleep>7hrs/night, etc.).
According to World Health Organization, children should exercise 60 min at moderate intensity per day with short bouts of anaerobic intensities and perform exercises to strengthen muscles and bones three times a week (World Health Organization 2010). The American College of Sports Medicine launched Exercise in Medicine in 2007, a global initiative designed to make exercise part of standard clinical care for people of all abilities (Medicine. 2021).
We already know that CVS risk factors models underestimate the risk for CVS disease events in adults with SCI (Barton TJ 2021). Assessing the role of inactivity related to pediatric-onset paralysis should be performed in a systematic way. In addition, prospective randomized studies with controls and adequate power are essential. A systematic analysis of the effect of exercise on functional and metabolic parameters that affect CVS health should be devised. Determining normative data for meaningful cardio-metabolic changes in children with paralysis should be undertaken. Looking at sensitive biomarkers of CVS health in the pediatric population, including those with paralysis is paramount. Instituting behavioral changes immediately after paralysis to offset the consequences of immobility should be a priority. Normalizing disability, and eliminating inequality to access to resources and care will require a societal intervention. Using technology to improve adherence to exercise and access to resources should be leveled.
