Different risk factor patterns for metabolic syndrome in men with spinal cord injury compared with able-bodied men despite similar prevalence rates

Cardiometabolic risk factor clustering in persons with spinal cord injury: A principal component analysis approach

CONTEXT/OBJECTIVE

To identify cardiometabolic (CM) measurements that cluster to confer increased cardiovascular disease (CVD) risk using principal component analysis (PCA) in a cohort of chronic spinal cord injury (SCI) and healthy non-SCI individuals.

APPROACH

A cross-sectional study was performed in ninety-eight non-ambulatory men with chronic SCI and fifty-one healthy non-SCI individuals (ambulatory comparison group). Fasting blood samples were obtained for the following CM biomarkers: lipid, lipoprotein particle, fasting glucose and insulin concentrations, leptin, adiponectin, and markers of inflammation. Total and central adiposity [total body fat (TBF) percent and visceral adipose tissue (VAT) percent, respectively] were obtained by dual x-ray absorptiometry (DXA). A PCA was used to identify the CM outcome measurements that cluster to confer CVD risk in SCI and non-SCI cohorts.

RESULTS

Using PCA, six factor-components (FC) were extracted, explaining 77% and 82% of the total variance in the SCI and non-SCI cohorts, respectively. In both groups, FC-1 was primarily composed of lipoprotein particle concentration variables. TBF and VAT were included in FC-2 in the SCI group, but not the non-SCI group. In the SCI cohort, logistic regression analysis results revealed that for every unit increase in the FC-1 standardized score generated from the statistical software during the PCA, there is a 216% increased risk of MetS (P = 0.001), a 209% increased risk of a 10-yr. FRS ≥ 10% (P = 0.001), and a 92% increase in the risk of HOMA2-IR ≥ 2.05 (P = 0.01).

CONCLUSION

Application of PCA identified 6-FC models for the SCI and non-SCI groups. The clustering of variables into the respective models varied considerably between the cohorts, indicating that CM outcomes may play a differential role on their conferring CVD-risk in individuals with chronic SCI.

Rowing exercise increases cardiorespiratory fitness and brachial artery diameter but not traditional cardiometabolic risk factors in spinal cord-injured humans

PURPOSE

This study assessed the effects of upper-body rowing exercise on cardiorespiratory fitness, traditional cardiometabolic risk factors, and vascular health in individuals with spinal cord injury (SCI).

METHODS

Seventeen male and female adults with chronic (> 1 yr) motor-complete and incomplete SCI (level of injury: C4-L3) were randomized to control (CON, n = 9) or exercise (UBROW, n = 8). Participants in UBROW performed 12-week, 3 weekly sessions of 30-min upper-body ergometer rowing exercise, complying with current exercise guidelines for SCI. Cardiorespiratory fitness ([Formula: see text]O2peak), traditional risk factors (lipid profile, glycemic control) as well as inflammatory and vascular endothelium-derived biomarkers (derived from fasting blood samples) were measured before and after 6 (6W) and 12 weeks (12W). Brachial artery resting diameter and flow-mediated dilation (FMD) were determined by ultrasound as exploratory outcomes.

RESULTS

UBROW increased [Formula: see text]O2peak from baseline (15.1 ± 5.1 mL/kg/min; mean ± SD) to 6W (16.5 ± 5.3; P < 0.01) and 12W (17.5 ± 6.1; P < 0.01). UBROW increased resting brachial artery diameter from baseline (4.80 ± 0.72 mm) to 12W (5.08 ± 0.91; P < 0.01), with no changes at 6W (4.96 ± 0.91), and no changes in CON. There were no significant time-by-group interactions in traditional cardiometabolic blood biomarkers, or in unadjusted or baseline diameter corrected FMD. Explorative analyses revealed inverse correlations between changes (∆12W-baseline) in endothelin-1 and changes in resting diameter (r = - 0.56) and FMD% (r = - 0.60), both P < 0.05.

CONCLUSION

These results demonstrate that 12 weeks of upper-body rowing complying with current exercise guidelines for SCI improves cardiorespiratory fitness and increases resting brachial artery diameter. In contrast, the exercise intervention had no or only modest effects on traditional cardiometabolic risk factors. The study was registered at Clinicaltrials.gov (N-20190053, May 15, 2020).

Twelve-Week Daily Gluteal and Hamstring Electrical Stimulation Improves Vascular Structure and Function, Limb Volume, and Sitting Pressure in Spinal Cord Injury: A Pilot Feasibility Study

OBJECTIVE

We examined the long-term effects of low-intensity electrical stimulation on (micro)vasculature and sitting pressure of a home-based, wearable electrical stimulation device in a pilot feasibility study.

DESIGN

In a cohort observation before-after trial, nine middle-aged male (n = 8) and female (n = 1) individuals (48 ± 15 yrs) with American Spinal Injury Association A-C classified chronic (1-24 yrs) spinal cord injury underwent 12 wks of self-administered daily, low-intensity gluteal and hamstring electrical stimulation (50 Hz, 6 hrs [30-min electrical stimulation, 15-min rest]). Common femoral artery diameter and blood blow were determined with ultrasound, skin vascular function during local heating was assessed using Laser-Doppler flowmetry, thigh volume was estimated using leg circumferences and skinfolds, and interface sitting pressure was measured using pressure mapping.

RESULTS

Resting common femoral artery diameter increased (0.73 ± 0.20 to 0.79 ± 0.22 cm, P < 0.001) and baseline common femoral artery blood flow increased (0.28 ± 0.12 to 0.40 ± 0.15 l/min, P < 0.002). Gluteal cutaneous vascular conductance showed a time*temperature interaction (P = 0.01) with higher conductance at 42°C after 12 wks. Ischial peak pressure decreased (P = 0.003) by 32 ± 23 mm Hg and pressure gradient decreased (23 ± 7 to 16 ± 6 mm Hg, P = 0.007). Thigh volume increased (+19%, P = 0.01).

CONCLUSIONS

Twelve-week daily home-based gluteal and hamstring electrical stimulation is feasible and effective to improve (micro)vasculature and sitting pressure, and electrical stimulation may have clinical implications for ameliorating pressure ulcers and (micro)vascular complications in spinal cord injury.

Endocrinological and inflammatory markers in individuals with spinal cord injury: A systematic review and meta-analysis

Spinal cord injury (SCI) can lead to dramatic physiological changes which can be a factor in developing secondary health conditions and might be reflected in biomarker changes in this elevated risk group. We focused specifically on the endocrine and inflammation profile differences between SCI and able-bodied individuals (ABI). Our aim was to determine the differences in inflammatory markers and endocrine profiles between SCI and ABI. We systematically searched 4 electronic databases for relevant studies. Human observational (cross-sectional, cohort, case-control) studies that compared biomarkers of interest between SCI and ABI population were included. Weighted mean difference between SCI and ABI was calculated using random-effects models. Heterogeneity was computed using I² statistic and chi-squared test. Study quality was evaluated through the Newcastle-Ottawa Scale. The search strategy yielded a total of 2,603 studies from which 256 articles were selected for full-text assessment. Sixty-two studies were included in the meta-analysis. SCI individuals had higher levels of pro-inflammatory C-reactive protein and IL-6 than ABI. Creatinine and 25-hydroxyvitamin D₃ levels were lower in SCI than ABI. Total testosterone levels and IGF-1 were also found to be lower, while cortisol and leptin levels were higher in SCI when compared to ABI. Accordingly, meta-regression, subgroup analysis, and leave-one-out analysis were performed, however, they were only able to partially explain the high levels of heterogeneity. Individuals with SCI show higher levels of inflammatory markers and present significant endocrinological changes when compared to ABI. Moreover, higher incidence of obesity, diabetes, osteoporosis, and hypogonadism in SCI individuals, together with decreased creatinine levels reflect some of the readily measurable aspects of the phenotype changes in the SCI group. These findings need to be considered in anticipating medically related complications and personalizing SCI medical care.

Energy expenditure and nutrient intake after spinal cord injury: a comprehensive review and practical recommendations

Many persons with spinal cord injury (SCI) have one or more preventable chronic diseases related to excessive energetic intake and poor eating patterns. Appropriate nutrient consumption relative to need becomes a concern despite authoritative dietary recommendations from around the world. These recommendations were developed for the non-disabled population and do not account for the injury-induced changes in body composition, hypometabolic rate, hormonal dysregulation and nutrition status after SCI. Because evidence-based dietary reference intake values for SCI do not exist, ensuring appropriate consumption of macronutrient and micronutrients for their energy requirements becomes a challenge. In this compressive review, we briefly evaluate aspects of energy balance and appetite control relative to SCI. We report on the evidence regarding energy expenditure, nutrient intake and their relationship after SCI. We compare these data with several established nutritional guidelines from American Heart Association, Australian Dietary Guidelines, Dietary Guidelines for Americans, Institute of Medicine Dietary Reference Intake, Public Health England Government Dietary Recommendations, WHO Healthy Diet and the Paralyzed Veterans of America (PVA) Clinical Practice Guidelines. We also provide practical assessment and nutritional recommendations to facilitate a healthy dietary pattern after SCI. Because of a lack of strong SCI research, there are currently limited dietary recommendations outside of the PVA guidelines that capture the unique nutrient needs after SCI. Future multicentre clinical trials are needed to develop comprehensive, evidence-based dietary reference values specific for persons with SCI across the care continuum that rely on accurate, individual assessment of energy need.

Selective Myostatin Inhibition Spares Sublesional Muscle Mass and Myopenia-Related Dysfunction after Severe Spinal Cord Contusion in Mice

Clinically relevant myopenia accompanies spinal cord injury (SCI), and compromises function, metabolism, body composition, and health. Myostatin, a transforming growth factor (TGF)β family member, is a key negative regulator of skeletal muscle mass. We investigated inhibition of myostatin signaling using systemic delivery of a highly selective monoclonal antibody - muSRK-015P (40 mg/kg) - that blocks release of active growth factor from the latent form of myostatin. Adult female mice (C57BL/6) were subjected to a severe SCI (65 kdyn) at T9 and were then immediately and 1 week later administered test articles: muSRK-015P (40 mg/kg) or control (vehicle or IgG). A sham control group (laminectomy only) was included. At euthanasia, (2 weeks post-SCI) muSRK-015P preserved whole body lean mass and sublesional gastrocnemius and soleus mass. muSRK-015P-treated mice with SCI also had significantly attenuated myofiber atrophy, lipid infiltration, and loss of slow-oxidative phenotype in soleus muscle. These outcomes were accompanied by significantly improved sublesional motor function and muscle force production at 1 and 2 weeks post-SCI. At 2 weeks post-SCI, lean mass was significantly decreased in SCI-IgG mice, but was not different in SCI-muSRK-015P mice than in sham controls. Total energy expenditure (kCal/day) at 2 weeks post-SCI was lower in SCI-immunoglobulin (Ig)G mice, but not different in SCI-muSRK-015P mice than in sham controls. We conclude that in a randomized, blinded, and controlled study in mice, myostatin inhibition using muSRK-015P had broad effects on physical, metabolic, and functional outcomes when compared with IgG control treated SCI animals. These findings may identify a useful, targeted therapeutic strategy for treating post-SCI myopenia and related sequelae in humans.

Dietetics After Spinal Cord Injury: Current Evidence and Future Perspectives

Following spinal cord injury (SCI), individuals are at high risk for obesity and several chronic cardiometabolic disorders due to a deterioration in body composition, hypometabolic rate, and endometabolic dysregulation. Countermeasures to the consequences of an SCI include adopting a healthy diet that provides adequate nutrition to maintain good body habitus and cardiometabolic health. A proper diet for individuals with SCI should distribute carbohydrates, protein, and fat to optimize a lower energy intake requirement and should stress foods with low caloric yet high nutrient density. The purpose of this article is to present available evidence on how nutritional status after SCI should advance future research to further develop SCI-specific guidelines for total energy intake, as it relates to percent carbohydrates, protein, fat, and all vitamins and minerals, that take into consideration the adaptations after SCI.

Cardiometabolic risks and atherosclerotic disease in ApoE knockout mice: Effect of spinal cord injury and Salsalate anti-inflammatory pharmacotherapy

OBJECTIVE

To test in mice with a double mutation of the ApoE gene (ApoE-/-) whether spinal cord injury (SCI) hastens the native trajectory of, and established component risks for, atherosclerotic disease (AD), and whether Salsalate anti-inflammatory pharmacotherapy attenuates the impact of SCI.

METHODS

ApoE-/- mice were anesthetized and underwent a T9 laminectomy. Exposed spinal cords were given a contusion injury (70 k-dynes). Sham animals underwent all surgical procedures, excluding injury. Injured animals were randomized to 2 groups: SCI or SCI+Salsalate [120 mg/Kg/day i.p.]. Mice were serially sacrificed at 20-, 24-, and 28-weeks post-SCI, and body mass was recorded. At sacrifice, heart and aorta were harvested intact, fixed in 10% buffered formalin, cleaned and cut longitudinally for en face preparation. The aortic tree was stained with oil-red-O (ORO). AD lesion histomorphometry was calculated from the proportional area of ORO. Plasma total cholesterol, triglycerides and proatherogenic inflammatory cytokines (PAIC's) were analyzed.

RESULTS

AD lesion in the aortic arch progressively increased in ApoE-/-, significant at 24- and 28-weeks. AD in SCI is significantly greater at 24- and 28-weeks compared to time-controlled ApoE-/-. Salsalate treatment attenuates the SCI-induced increase at these time points. Body mass in all SCI groups are significantly reduced compared to time-controlled ApoE-/-. Cholesterol and triglycerides are significantly higher with SCI by 24- and 28-weeks, compared to ApoE-/-, and Salsalate reduces the SCI-induced effect on cholesterol. PAIC's interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor α (TNFα), monocyte chemoattractant protein-1 (MCP-1), and chemokine (C-C motif) ligand 5 (CCL-5) are significantly greater with SCI compared to ApoE-/- at varying timepoints. Salsalate confers a marginal reducing effect on PAIC's by 28-weeks compared to SCI. Regression models determine that each PAIC is a significant and positive predictor of lesion. (p's <0.05).

CONCLUSIONS

SCI accelerates aortic AD and associated risk factors, and anti-inflammatory treatment may attenuate the impact of SCI on AD outcomes. PAIC's IL-1β, IL-6, TNFα, MCP-1, and CCL-5 may be effective predictors of AD.

Neurogenic Obesity and Skeletal Pathology in Spinal Cord Injury

Spinal cord injury (SCI) results in dramatic changes in body composition, with lean mass decreasing and fat mass increasing in specific regions that have important cardiometabolic implications. Accordingly, the recent Consortium for Spinal Cord Medicine (CSCM) released clinical practice guidelines for cardiometabolic disease (CMD) in SCI recommending the use of compartmental modeling of body composition to determine obesity in adults with SCI. This recommendation is guided by the fact that fat depots impact metabolic health differently, and in SCI adiposity increases around the viscera, skeletal muscle, and bone marrow. The contribution of skeletal muscle atrophy to decreased lean mass is self-evident, but the profound loss of bone is often less appreciated due to methodological considerations. General-population protocols for dual-energy x-ray absorptiometry (DXA) disregard assessment of the sites of greatest bone loss in SCI, but the International Society for Clinical Densitometry (ISCD) recently released an official position on the use of DXA to diagnose skeletal pathology in SCI. In this review, we discuss the recent guidelines regarding the evaluation and monitoring of obesity and bone loss in SCI. Then we consider the possible interactions of obesity and bone, including emerging evidence suggesting the possible influence of metabolic, autonomic, and endocrine function on bone health in SCI.

Exercise Interventions Targeting Obesity in Persons With Spinal Cord Injury

Spinal cord injury (SCI) results in an array of cardiometabolic complications, with obesity being the most common component risk of cardiometabolic disease (CMD) in this population. Recent Consortium for Spinal Cord Medicine Clinical Practice Guidelines for CMD in SCI recommend physical exercise as a primary treatment strategy for the management of CMD in SCI. However, the high prevalence of obesity in SCI and the pleiotropic nature of this body habitus warrant strategies for tailoring exercise to specifically target obesity. In general, exercise for obesity management should aim primarily to induce a negative energy balance and secondarily to increase the use of fat as a fuel source. In persons with SCI, reductions in the muscle mass that can be recruited during activity limit the capacity for exercise to induce a calorie deficit. Furthermore, the available musculature exhibits a decreased oxidative capacity, limiting the utilization of fat during exercise. These constraints must be considered when designing exercise interventions for obesity management in SCI. Certain forms of exercise have a greater therapeutic potential in this population partly due to impacts on metabolism during recovery from exercise and at rest. In this article, we propose that exercise for obesity in SCI should target large muscle groups and aim to induce hypertrophy to increase total energy expenditure response to training. Furthermore, although carbohydrate reliance will be high during activity, certain forms of exercise might induce meaningful postexercise shifts in the use of fat as a fuel. General activity in this population is important for many components of health, but low energy cost of daily activities and limitations in upper body volitional exercise mean that exercise interventions targeting utilization and hypertrophy of large muscle groups will likely be required for obesity management.

Traditional Cardiovascular Risk Factors Strongly Underestimate the 5-Year Occurrence of Cardiovascular Morbidity and Mortality in Spinal Cord Injured Individuals

OBJECTIVES

To explore whether traditional models of cardiovascular disease (CVD) risk prediction correctly predict CVD events across a median 5.7-year follow-up period in individuals with spinal cord injury (SCI) and whether adding SCI-related characteristics (ie, lesion level) to the prediction model can improve the prognostic value.

DESIGN

Retrospective analysis of patient records.

SETTING

Observation at the start of active rehabilitation of participants in a multicenter cohort study, "Restoration of (Wheelchair) Mobility in SCI Rehabilitation," in the Netherlands.

PARTICIPANTS

Patients with SCI (N=200) The patients were 74% men, aged 40±14 years, and with an American Spinal Injury Association (ASIA) impairment score of A through D. Forty percent had tetraplegia, and 69% were motor complete.

INTERVENTIONS

Risk profiling/not applicable.

MAIN OUTCOME MEASURES

Survival status and cardiovascular morbidity and mortality qwere obtained from medical records. Five-year Framingham Risk Scores (FRS) and the FRS ability to predict events assessed using receiver operating characteristic (ROC) curves with corresponding areas under the curve (AUC) and 95% confidence intervals (CI). Kaplan-Meier curves and the log-rank test were used to assess the difference in clinical outcome between participants with an FRS score lower or higher than the median FRS score for the cohort. SCI-related factors associated with CVD events, ASIA impairment, motor completeness, level of injury, and sports participation before injury were explored using univariate and multivariate Cox proportional hazard regression.

RESULTS

The median 5-year FRS was 1.36%. Across a median follow-up period of 5.7 years, 39 developed a CVD event, including 10 fatalities. Although the FRS markedly underestimated the true occurrence of CVD events, the Kaplan-Meier curves and the log-rank test showed that the risk ratio for individuals with an FRS score less than the median FRS (eg, low risk) versus a score greater than the median FRS (high risk) was 3.2 (95% CI, 1.6-6.5; P=.001). Moreover, ROC with corresponding AUCs suggests acceptable accuracy of the FRS to identify individuals with increased risk for future CVD events (ROC AUC of 0.71; 95% CI, 0.62-0.82). Adding ASIA impairment (0.74; 95% CI, 0.66-0.82), motor impairment (0.74; 95% CI, 0.66-0.83), level of injury (0.72; 95% CI, 0.63-0.81), or active engagement in sport before injury (0.72; 95% CI, 0.63-0.88) to the FRS did not improve the level of discrimination.

CONCLUSIONS

Our 5.7-year retrospective study reveals that cardiovascular risk factors and risk models markedly underestimate the true risk for CVD events in individuals with SCI. Nonetheless, these markers successfully distinguish between SCI individuals at high versus low risk for future CVD events. Our data may have future clinical implications, both related to (cutoff values of) CVD risk factors, but also for (earlier) prescription of (non)pharmacologic strategies against CVD in SCI individuals.

Classification of obesity, cardiometabolic risk, and metabolic syndrome in adults with spinal cord injury

Objective: To describe and compare (1) classification of obesity using clinical proxies of body composition that are easily accessible in the outpatient clinic setting, (2) cardiometabolic risk using existing screening tools and staging systems, and (3) the presence of metabolic syndrome (MetS) using four commonly-used definitions in adults with spinal cord injury (SCI). Design: Retrospective chart review Setting: Outpatient Veterans Affairs (VA) SCI Annual Evaluation Clinic Participants: Patients who attended an annual evaluation appointment with demographic, anthropometric, and biochemical data documented in their medical records as part of routine medical care. Outcome measures: Obesity classification (body mass index, waist circumference, ideal body weight percentage), cardiometabolic risk scores (Framingham Risk Score, Cardiometabolic Disease Staging System, Edmonton Obesity Staging System), and MetS classification (using four commonly-used definitions) were described and compared. Results: Of the 155 veterans included in this analysis, 93% were considered "at risk" by at least one of the measurements studied. However, there was considerable variation between the different screening tools. The κ-agreement between various definitions of MetS ranged from fair to moderate. Conclusion: Screening tools that were developed for the non-SCI population produced variable assessments of risk when applied to veterans with SCI. Due to the fair to moderate inter-rater agreement between MetS definitions, it is unknown which definition is superior to identify MetS in the SCI population. An SCI-specific screening tool is needed to accurately classify obesity, cardiometabolic risk, and MetS in order to provide timely education and intervention.

Instruments Measuring Physical Activity in Individuals Who Use a Wheelchair: A Systematic Review of Measurement Properties

OBJECTIVE

To systematically review the evidence evaluating validity or reliability of self-reported and device-based instruments, to measure physical activity (PA) in individuals who use a wheelchair, and to make recommendations for the selection of PA outcomes tools.

DATA SOURCES

PubMed, Embase, and CINAHL were systematically searched.

STUDY SELECTION

Studies reporting measurement properties of instruments to assess PA in individuals who use a wheelchair.

DATA EXTRACTION

The Consensus-Based Standards for the Selection of Health Status Measurement Instruments checklist was used to assess the methodological quality of the included studies. The measurement properties of instruments assessing PA were examined.

DATA SYNTHESIS

The search yielded 5341 records, 61 were considered relevant, 21 articles were included. A best evidence synthesis was performed on 9 studies including 4 self-reported instruments and 13 studies including 8 device-based instruments. One study evaluated both self-reported and device-based instruments. The overall methodological quality of all studies ranged from poor to excellent. Variable levels of evidence were found for both the validity and reliability for self-reported instruments and for criterion validity for device-based instruments.

CONCLUSIONS

The Physical Activity Scale for Individuals with Disabilities (PASIPD) and The Physical Activity Recall Assessment for People with Spinal Cord Injury (PARA-SCI) seem the most promising self-reported instruments for measuring the intensity of PA. Device-based instruments that can be used for measuring both the intensity and type of PA are the GENEActiv, Actigraph GT3X+, Actiheart, or the Physical Activity Monitor System (PAMS), showing moderate evidence for a positive rating of criterion validity. For measuring the type of PA, the PAMS and VitaMove are suitable, showing both good evidence for a positive rating of criterion validity.

A cross-sectional comparison between cardiorespiratory fitness, level of lesion and red blood cell distribution width in adults with chronic spinal cord injury

OBJECTIVES

To assess; (1) differences in red blood cell distribution width between individuals with chronic (>1year), motor-complete cervical (n=21), upper-thoracic (n=27) and thoracolumbar (n=15) spinal cord injury and, (2) associations between red blood cell distribution width and cardiorespiratory fitness.

DESIGN

Prospective multi-center, cross-sectional study.

METHODS

Peak oxygen uptake was determined using an upper-body arm-crank exercise test to volitional exhaustion and red blood cell distribution width was measured using an automated hematology system.

RESULTS

There were significant (p<0.009) differences between groups classified by level of injury in absolute and relative peak oxygen uptake, peak power output and red blood cell distribution width. A significant (p<0.001) large negative association (r = -0.524) was found between relative peak oxygen uptake and red blood cell distribution width. Unbiased recursive partitioning, while revealing study site specific differences in red blood cell distribution width, identified homogenous subgroups based specifically on cardiorespiratory fitness irrespective of additional demographic and injury characteristics.

CONCLUSION

The strong negative association between cardiorespiratory fitness and red blood cell distribution width in individuals with paraplegia parallel those previously observed in non-disabled individuals. Higher red blood cell distribution width values are an independent risk factor for increased cardiovascular mortality, heart failure, and coronary heart disease and may reflect several underlying exacerbated metabolic responses such as oxidative stress and systemic inflammation. These data emphasize the importance of maintaining a high aerobic capacity following spinal cord injury.

Effects of ursolic acid on sub-lesional muscle pathology in a contusion model of spinal cord injury

Spinal Cord Injury (SCI) results in severe sub-lesional muscle atrophy and fiber type transformation from slow oxidative to fast glycolytic, both contributing to functional deficits and maladaptive metabolic profiles. Therapeutic countermeasures have had limited success and muscle-related pathology remains a clinical priority. mTOR signaling is known to play a critical role in skeletal muscle growth and metabolism, and signal integration of anabolic and catabolic pathways. Recent studies show that the natural compound ursolic acid (UA) enhances mTOR signaling intermediates, independently inhibiting atrophy and inducing hypertrophy. Here, we examine the effects of UA treatment on sub-lesional muscle mTOR signaling, catabolic genes, and functional deficits following severe SCI in mice. We observe that UA treatment significantly attenuates SCI induced decreases in activated forms of mTOR, and signaling intermediates PI3K, AKT, and S6K, and the upregulation of catabolic genes including FOXO1, MAFbx, MURF-1, and PSMD11. In addition, UA treatment improves SCI induced deficits in body and sub-lesional muscle mass, as well as functional outcomes related to muscle function, motor coordination, and strength. These findings provide evidence that UA treatment may be a potential therapeutic strategy to improve muscle-specific pathological consequences of SCI.

Exercise and Health-Related Risks of Physical Deconditioning After Spinal Cord Injury

A sedentary lifestyle occurring soon after spinal cord injury (SCI) may be in contrast to a preinjury history of active physical engagement and is thereafter associated with profound physical deconditioning sustained throughout the lifespan. This physical deconditioning contributes in varying degrees to lifelong medical complications, including accelerated cardiovascular disease, insulin resistance, osteopenia, and visceral obesity. Unlike persons without disability for whom exercise is readily available and easily accomplished, exercise options for persons with SCI are more limited. Depending on the level of injury, the metabolic responses to acute exercise may also be less robust than those accompanying exercise in persons without disability, the training benefits more difficult to achieve, and the risks of ill-considered exercise both greater and potentially irreversible. For exercise to ultimately promote benefit and not impose additional impairment, an understanding of exercise opportunities and risks if exercise is undertaken by those with SCI is important. The following monograph will thus address common medical challenges experienced by persons with SCI and typical modes and benefits of voluntary exercise conditioning.

Nutritional Health Considerations for Persons with Spinal Cord Injury

Chronic spinal cord injury (SCI) often results in morbidity and mortality due to all-cause cardiovascular disease (CVD) and comorbid endocrine disorders. Several component risk factors for CVD, described as the cardiometabolic syndrome (CMS), are prevalent in SCI, with the individual risks of obesity and insulin resistance known to advance the disease prognosis to a greater extent than other established risks. Notably, adiposity and insulin resistance are attributed in large part to a commonly observed maladaptive dietary/nutritional profile. Although there are no evidence-based nutritional guidelines to address the CMS risk in SCI, contemporary treatment strategies advocate more comprehensive lifestyle management that includes sustained nutritional guidance as a necessary component for overall health management. This monograph describes factors in SCI that contribute to CMS risks, the current nutritional profile and its contribution to CMS risks, and effective treatment strategies including the adaptability of the Diabetes Prevention Program (DPP) to SCI. Establishing appropriate nutritional guidelines and recommendations will play an important role in addressing the CMS risks in SCI and preserving optimal long-term health.

The analysis of serum lipid levels in patients with spinal cord injury

STUDY DESIGN

Retrospective study.

OBJECTIVES

The purposes of this investigation were to evaluate the serum lipid profile among a broad sample of patients with spinal cord injury (SCI), examining the impact of disease duration, lesion level, lesion grade and functional activity level on serum lipid levels of patients with SCI.

SETTING

Ankara Physical Medicine and Rehabilitation Training and Research Hospital, Turkey.

METHODS

Serum lipid profiles of 269 participants with SCI were analyzed and correlated to disease duration, lesion level, lesion grade and ambulation status.

RESULTS

Total cholesterol (TC) was higher than normal in 21.2%, low density lipoprotein cholesterol in 24.4%, and triglycerides levels in 31% of the patients. The high density lipoprotein cholesterol (HDL-c) level was found to be lower than 40 mg/dl in 79.5% of the patients, TC/HDL-c ratio was 4.5 and above in 65.7% of the patients in our study. TC/HDL-c ratio was significantly higher in patients with SCI with a disease duration of 0-12 months than the group with a longer disease duration (P = 0.009). TC/HDL-c ratio was significantly higher in patients who could not be community ambulated than the patients who were community ambulated (P = 0.005). HDL-c levels in patients with motor complete SCI were significantly lower than patients with motor incomplete SCI (P = 0.028).

CONCLUSION

Dyslipidemia is observed in a large number of patients with SCI. The risk of dyslipidemia was seen to have increased in motor complete SCI patients, in patients who can not be community ambulated and whose disease duration is between 0 to 12 months.

Comorbidity and physical activity in people with paraplegia: a descriptive cross-sectional study

STUDY DESIGN

Descriptive cross-sectional study.

SETTING

The study was conducted in the Spinal Cord Injury Unit of the University Vall d'Hebron Hospital and in the Physical Education and Sports Department of the University of Valencia.

OBJECTIVES

The aim of this study was to quantify the presence of comorbidities in spinal cord injury (SCI) subjects who did or did not perform regular physical activity (PA) and to identify the relationship between PA and the level of comorbidity.

METHODS

The sample consisted of patients with complete motor SCI (T2-T12), who were fitted with an accelerometer attached to the non-dominant wrist for a period of 1 week. The clinical and blood analytic variables were selected by an expert panel.

RESULTS

In the exploratory analysis, we have found differences in the total number of pathologies between active and inactive patients, with fewer total pathologies in the active patient group. An association was found between the PA level and diabetes mellitus (; P=0.047; φ=0.25). We also observed an association between the cardioprotector level of high-density lipoprotein (HDL)-cholesterol and PA level (; P=0.057; Φ0.24).

CONCLUSIONS

Our results suggest that patients considered active showed lower total comorbidity than inactive patients and higher protection levels against developing cardiovascular comorbidity.

Methods for classifying obesity in spinal cord injury: a review

STUDY DESIGN

Narrative review.

OBJECTIVES

Review methods used to measure and classify obesity in individuals with spinal cord injuries (SCI). Outline the strengths and weaknesses of each method used to measure obesity in individuals with SCI.

SETTING

International.

METHODS

PubMed was used to identify articles before 2016. Search terms ('obesity' or 'weight status' and 'spinal cord injury'). Filters: adults, English and human. Studies were retained that (1) included participants, 18 years or older, with SCI; (2) took place in inpatient, outpatient or community-based settings and (3) measured obesity status. Unique methods for classifying individuals with SCI as obese were identified and examples are presented.

RESULTS

Methods identified for classifying obesity were as follows: World Health Organization body mass index (BMI) cutoff⩾30 kg m^-2, BMI cutoff ⩾25-29 kg m^-2, and SCI-specific BMI cutoff ⩾22 kg m^-2, waist circumference cutoff (women >102 cm, men >88 cm), percent body fat cutoffs ⩾25% using bioelectrical impedance analysis and dual-energy X-ray absorptiometry, computerized tomography scan visceral fat area ⩾100 cm² and percentage of ideal body weight.

CONCLUSIONS

BMI is the most widely used measure of obesity in the SCI literature. Although some studies identified alternative cutoffs or other metrics, there is no standardized obesity classification in SCI. However, research is needed to determine and validate obesity classification specific to SCI due to physiological changes that occur following injury. We recommend that researchers and clinicians proceed with caution and use methodology based on the purpose of measurement.

A lifestyle intervention program for successfully addressing major cardiometabolic risks in persons with SCI: a three-subject case series

INTRODUCTION

This study is a prospective case series analyzing the effects of a comprehensive lifestyle intervention program in three patients with chronic paraplegia having major risks for the cardiometabolic syndrome (CMS).

CASE PRESENTATION

Individuals underwent an intense 6-month program of circuit resistance exercise, nutrition using a Mediterranean diet and behavioral support, followed by a 6-month extension (maintenance) phase involving minimal support. The primary goal was a 7% reduction of body mass. Other outcomes analyzed insulin resistance using the HOMA-IR model, and plasma levels of fasting triglycerides and high-density lipoprotein cholesterol. All participants achieved the goal for 7% reduction of body mass and maintained the loss after the MP. Improvements were observed in 2/3 subjects for HOMA-IR and high-density lipoprotein cholesterol. All participants improved their risk for plasma triglycerides.

DISCUSSION

We conclude, in a three-person case series of persons with chronic paraplegia, a lifestyle intervention program involving circuit resistance training, a calorie-restrictive Mediterranean-style diet and behavioral support, results in clinically significant loss of body mass and effectively reduced component risks for CMS and diabetes. These results were for the most part maintained after a 6-month MP involving minimal supervision.

Benefits of an exercise wellness program after spinal cord injury

OBJECTIVE

To describe the initial benefits of a structured group exercise program on exercise frequency and intensity, perceived health, pain, mood, and television watching habits.

DESIGN

Pre-test/post-test.

PARTICIPANTS/METHODS

Eighty-nine persons with SCI participated voluntarily in a no-cost, twice weekly physical therapy group exercise class over 3 months. Forty-five persons completed pre- and post-participation interviews on exercise frequency and intensity, perceived health, pain, mood, sleep, and television watching habits.

RESULTS

Mean participant age of the respondents was 43.82 years. 49% had AIS C or D injuries, 24% had AIS A,B paraplegia, 9% had AIS A,B C1-C4 and 18% had AIS A,B C5-C8. 75.6% of participants were male and 84.4% had a traumatic etiology as the cause of their SCI. There was a significant improvement in days of strenuous and moderate exercise as well as health state. There was an average decrease in pain scores, depression scores, number of hours spent watching television, and days/week of mild exercise.

CONCLUSION

Participation in structured, small group exercise as a component of a wellness program after SCI shows promise for improving regular exercise participation and health state, but benefits may also occur across other areas of health and function including mood, pain, and hours spent watching television. Further follow-up is needed to determine whether improvements can be maintained after program completion and across all neurological levels.

Vitamin D and spinal cord injury: should we care?

STUDY DESIGN

Narrative review.

OBJECTIVES

This review provides an overview of the etiological factors and consequences of vitamin D insufficiency in relation to spinal cord injury (SCI) as well as important considerations for vitamin D supplementation.

SETTING

Montreal, Canada.

METHODS

Literature search.

RESULTS

Vitamin D insufficiency is common in SCI individuals owing to the presence of many contributing factors including limited sun exposure and intake, use of medication and endocrine perturbations. Although there are several biological plausible mechanisms by which vitamin D may act upon musculoskeletal and cardiometabolic health, the impact of vitamin D insufficiency on such systems remains ill defined in SCI. In the absence of guidelines for the management of vitamin D insufficiency in this high-risk population and in an attempt to provide clinical guidance, considerations for vitamin D supplementation such as the type of vitamin D, dosing regimens and toxicity are discussed and tentative recommendations suggested with particular reference to issues faced by SCI patients.

CONCLUSION

Although high rates of vitamin D insufficiency are encountered in SCI individuals, its consequences and the amount of vitamin D required to prevent insufficiency are still unknown, indicating a need for more intervention studies with well-defined outcome measures. Routine screening and monitoring of vitamin D as well as treatment of suboptimal status should be instituted in both acute and chronic setting. The close interactions between vitamin D and related bone minerals should be kept in mind when supplementing SCI individuals, and practices should be individualized with clinical conditions.

Metabolic syndrome in people with a long-standing spinal cord injury: associations with physical activity and capacity

This study investigated (i) the prevalence of the metabolic syndrome (MetS) in people with a long-standing spinal cord injury (SCI); (ii) whether personal or lesion characteristics are determinants of the MetS; and (iii) the association with physical activity or peak aerobic capacity on the MetS. In a cross-sectional study, persons with SCI (N = 223; time since injury of ≥10 years) were tested. The individual components of the MetS were assessed together with the physical activity measured by the Physical Activity Scale for Individuals with Physical Disabilities (PASIPD), while peak aerobic capacity was tested during a graded wheelchair exercise test on a treadmill. Thirty-nine percent of the participants had MetS. In a multivariate logistic regression analyses and after performing a backward regression analysis, only age and education were significant determinants of the MetS. A 10-year increase in age leads to a 1.5 times more chance to have the MetS. Furthermore, people with a low education will multiply the relative risk of MetS compared with people with high education by almost 2. With and without correcting for confounders, no significant relationship was found between PASIPD or peak aerobic capacity and the MetS. It can be concluded that the prevalence of the MetS is high (39%) in people with a long-standing SCI but is comparable to the general Dutch population. Older people and those with a lower education level are most at risk for the MetS. Physical activity and peak aerobic fitness were not related to the MetS in this group with a long-standing SCI.

Reducing cardiometabolic disease in spinal cord injury

Accelerated cardiometabolic disease is a serious health hazard after spinal cord injuries (SCI). Lifestyle intervention with diet and exercise remains the cornerstone of effective cardiometabolic syndrome treatment. Behavioral approaches enhance compliance and benefits derived from both diet and exercise interventions and are necessary to assure that persons with SCI profit from intervention. Multitherapy strategies will likely be needed to control challenging component risks, such as gain in body mass, which has far reaching implications for maintenance of daily function as well as health.

Allostatic load and spinal cord injury: review of existing research and preliminary data

OBJECTIVE

To introduce allostatic load (AL) as a framework for measuring stress-related outcomes after spinal cord injury (SCI) by identifying the number and nature of biomarkers investigated in existing studies and by generating preliminary data on AL in 30 persons with traumatic SCI.

METHODS

This systematic review and pilot study were conducted at a medical university in the southeastern United States. A review of literature published between 1993 and 2012 identified studies using 2 or more of 5 classes of AL biomarkers. We then collected data on 11 biomarkers (n = 30) from self-selected participants using physical exams and blood and urine specimen collection. These included waist to hip ratio, systolic and diastolic blood pressure, total cholesterol, high-density lipoprotein cholesterol, dihydroepiandrosterone, glycosylated hemoglobin, C-reactive protein, interleukin-6, and cortisol, norepinephrine, and epinephrine normalized by 12-hour creatinine.

RESULTS

We were unable to identify any studies investigating AL biomarkers from each of the 5 areas or any studies specifically proposing to investigate AL. AL scores were relatively low, with metabolic indicators being the most elevated and neuroendocrine the least elevated.

CONCLUSIONS

AL is a promising, yet underutilized, construct that may be feasibly assessed after SCI.

Spinal cord injury increases the risk of type 2 diabetes: a population-based cohort study

BACKGROUND CONTEXT

Previous studies on the risk and prevalence of diabetes among spinal cord injury (SCI) patients are limited and controversial.

PURPOSE

To compare the risk and incidence rate (IR) of Type 2 diabetes in SCI and non-SCI patients.

STUDY DESIGN

This is a population-based retrospective cohort study.

PATIENT SAMPLE

Data from Taiwan's National Health Insurance Research Database for the period 1997 to 2010 were analyzed. Patients aged 20 years and older newly identified with SCIs during this period were included in the SCI cohort. A non-SCI comparison cohort was randomly selected from National Health Insurance beneficiaries and matched with the SCI cohort based on age, sex, and index date.

OUTCOME MEASURES

Both cohorts were followed until the first of the following occurred: the diagnosis of Type 2 diabetes (International Classification of Disease, Ninth Revision, Clinical Modification codes 250), withdrawal from the insurance system, the end of 2010, or death.

METHODS

A Cox proportional hazards regression analysis was used to estimate the risk of developing diabetes.

RESULTS

Taiwan possesses an older SCI population, with a mean age of 51.6 years. The IR for diabetes in patients with and without SCIs was 22.1 per 10,000 person-years and 17.2 per 10,000 person-years, respectively. The adjusted hazard ratio (HR) for diabetes was 1.33 times higher in patients with SCIs than in those without SCIs. In patients with SCIs, men (adjusted HR=1.23, 95% confidence interval (CI)=1.04-1.44), older people (adjusted HR=4.26 in patients older than 65 years, 95% CI=3.16-5.74), patients with comorbidity (adjusted HR=1.36, 95% CI=1.14-1.62), and patients with a complete thoracic SCI (T-spine injury) (adjusted HR=2.13, 95% CI=0.95-4.79) were more likely to be diagnosed with diabetes than other patient subgroups.

CONCLUSIONS

Our findings may facilitate the prioritizing of preventive health strategies and planning of long-term care for SCI patients.

Structural and functional left ventricular impairment in subjects with chronic spinal cord injury and no overt cardiovascular disease

CONTEXT

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in subjects with long-term spinal cord injury (SCI). More specific recommendations for CVD prevention in this population are needed.

METHODS

One hundred thirty male subjects (47 subjects with SCI and 83 able-bodied persons (ABPs), mean age 43.89 ± 1.9 and 45.44 ± 12.2 years; P = 0.48) underwent transthoracic echocardiography (TTE). The effects of age, weight, mean arterial pressure (MAP) and level of physical training on cardiac adaptations were evaluated through multiple regression analysis.

RESULTS

In subjects with SCI, TTE revealed increased wall thickness (P < 0.05), lower E wave, E/A ratio and early diastolic myocardial relaxation velocity on Tissue Doppler Imaging (TDI) (P < 0.05) and higher systolic myocardial contraction velocity on TDI (0.10 ± 0.02 vs. 0.09 ± 0.02 m/seconds, P = 0.002) and peak systolic pressure to end-systolic volume ratio (3.62 ± 1.39 vs. 2.82 ± 0.90, P < 0.001) compared with ABPs. Aortic diameters were larger in subjects with SCI than ABPs. Differences remained statistically significant even after adjustment for age, weight, MAP, and level of physical training. Weight and age were found to be independent variables that substantially affected left ventricular structure and function in subjects with SCI.

CONCLUSIONS

Subjects with post-traumatic chronic SCI and no overt cardiovascular risk factors, exhibit initial left ventricular remodeling (as assessed by TTE) compared with ABPs. Lifestyle modifications, including regular physical exercise and weight control, should be implemented in all subjects with SCI, even at a very early stage, in order to reduce cardiovascular risk and prevent the development of CVD.

Dietary intake relative to cardiovascular disease risk factors in individuals with chronic spinal cord injury: a pilot study

BACKGROUND

The relationship between cardiovascular disease (CVD) risk factors and dietary intake is unknown among individuals with spinal cord injury (SCI).

OBJECTIVE

To investigate the relationship between consumption of selected food groups (dairy, whole grains, fruits, vegetables, and meat) and CVD risk factors in individuals with chronic SCI.

METHODS

A cross-sectional substudy of individuals with SCI to assess CVD risk factors and dietary intake in comparison with age-, gender-, and race-matched able-bodied individuals enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Dietary history, blood pressure, waist circumference (WC), fasting blood glucose, high-sensitivity C-reactive protein (hs-CRP), lipids, glucose, and insulin data were collected from 100 SCI participants who were 38 to 55 years old with SCI >1 year and compared to 100 matched control participants from the CARDIA study.

RESULTS

Statistically significant differences between SCI and CARDIA participants were identified in WC (39.2 vs 36.2 in.; P < .001) and high-density lipoprotein cholesterol (HDL-C; 39.2 vs 47.5 mg/dL; P < .001). Blood pressure, total cholesterol, triglycerides, glucose, insulin, and hs-CRP were similar between SCI and CARDIA participants. No significant relation between CVD risk factors and selected food groups was seen in the SCI participants.

CONCLUSION

SCI participants had adverse WC and HDL-C compared to controls. This study did not identify a relationship between consumption of selected food groups and CVD risk factors.

Serum lipid concentrations among persons with spinal cord injury - a systematic review and meta-analysis of the literature

BACKGROUND

Lipid optimization comprises a therapeutic cornerstone of primary and secondary cardiovascular disease prevention. This systematic review and meta-analysis sought to clarify patterns of lipid profiles in spinal cord injury (SCI) patients compared to able-bodied individuals as well as among subgroups of SCI patients stratified by sex, activity level, race, and level of injury.

METHODS

Searches were conducted in PubMed, CINAHL, PsycINFO, and EMBASE. The initial literature search broadly identified peer-reviewed studies that examined cardiovascular risk factors in SCI. A total of 50 studies were ultimately identified that focused on lipid levels in SCI. Demographic data (including subject age, duration of injury, height, weight, and body mass index [BMI]) and lipid values were extracted for able-bodied individuals and subjects with SCI. Statistical analyses included t-testing and analysis of variance (ANOVA).

RESULTS

Compared with controls, individuals with SCI had significantly lower total cholesterol (TC) (183.4 mg/dL versus 194.9 mg/dL, p = 0.019) and high-density lipoprotein cholesterol (HDL-C) (41.0 mg/dL versus 49.6 mg/dL, p < 0.001) and higher TC/HDL-C ratios (4.5 versus 4.0, p = 0.002), though no significant differences were found for triglyceride (TG) and non-HDL-C values.

CONCLUSIONS

SCI represents an increasingly common chronic condition, now secondarily characterized by heightened CVD risk potentially in part due to unique lipid profiles characterized primarily by low HDL-C and an increased TC/HDL-C ratio. As other at-risk patient populations have received increased acknowledgment with more stringent lipid panel screening at earlier ages and increased frequency, we would propose that the same be implemented for the SCI population until more-specific CVD risk stratification guidelines are established for this population.

Neuroendocrine and cardiac metabolic dysfunction and NLRP3 inflammasome activation in adipose tissue and pancreas following chronic spinal cord injury in the mouse

CVD (cardiovascular disease) represents a leading cause of mortality in chronic SCI (spinal cord injury). Several component risk factors are observed in SCI; however, the underlying mechanisms that contribute to these risks have not been defined. Central and peripheral chronic inflammation is associated with metabolic dysfunction and CVD, including adipokine regulation of neuroendocrine and cardiac function and inflammatory processes initiated by the innate immune response. We use female C57 Bl/6 mice to examine neuroendocrine, cardiac, adipose and pancreatic signaling related to inflammation and metabolic dysfunction in response to experimentally induced chronic SCI. Using immuno-histochemical, -precipitation, and -blotting analysis, we show decreased POMC (proopiomelanocortin) and increased NPY (neuropeptide-Y) expression in the hypothalamic ARC (arcuate nucleus) and PVN (paraventricular nucleus), 1-month post-SCI. Long-form leptin receptor (Ob-Rb), JAK2 (Janus kinase)/STAT3 (signal transducer and activator of transcription 3)/p38 and RhoA/ROCK (Rho-associated kinase) signaling is significantly increased in the heart tissue post-SCI, and we observe the formation and activation of the NLRP3 (NOD-like receptor family, pyrin domain containing 3) inflammasome in VAT (visceral adipose tissue) and pancreas post-SCI. These data demonstrate neuroendocrine signaling peptide alterations, associated with central inflammation and metabolic dysfunction post-SCI, and provide evidence for the peripheral activation of signaling mechanisms involved in cardiac, VAT and pancreatic inflammation and metabolic dysfunction post-SCI. Further understanding of biological mechanisms contributing to SCI-related inflammatory processes and metabolic dysfunction associated with CVD pathology may help to direct therapeutic and rehabilitation countermeasures.

Cardiometabolic risk clustering in spinal cord injury: results of exploratory factor analysis

BACKGROUND

Evidence suggests an elevated prevalence of cardiometabolic risks among persons with spinal cord injury (SCI); however, the unique clustering of risk factors in this population has not been fully explored.

OBJECTIVE

The purpose of this study was to describe unique clustering of cardiometabolic risk factors differentiated by level of injury.

METHODS

One hundred twenty-one subjects (mean 37 ± 12 years; range, 18-73) with chronic C5 to T12 motor complete SCI were studied. Assessments included medical histories, anthropometrics and blood pressure, and fasting serum lipids, glucose, insulin, and hemoglobin A1c (HbA1c).

RESULTS

The most common cardiometabolic risk factors were overweight/obesity, high levels of low-density lipoprotein (LDL-C), and low levels of high-density lipoprotein (HDL-C). Risk clustering was found in 76.9% of the population. Exploratory principal component factor analysis using varimax rotation revealed a 3-factor model in persons with paraplegia (65.4% variance) and a 4-factor solution in persons with tetraplegia (73.3% variance). The differences between groups were emphasized by the varied composition of the extracted factors: Lipid Profile A (total cholesterol [TC] and LDL-C), Body Mass-Hypertension Profile (body mass index [BMI], systolic blood pressure [SBP], and fasting insulin [FI]); Glycemic Profile (fasting glucose and HbA1c), and Lipid Profile B (TG and HDL-C). BMI and SBP formed a separate factor only in persons with tetraplegia.

CONCLUSIONS

Although the majority of the population with SCI has risk clustering, the composition of the risk clusters may be dependent on level of injury, based on a factor analysis group comparison. This is clinically plausible and relevant as tetraplegics tend to be hypo- to normotensive and more sedentary, resulting in lower HDL-C and a greater propensity toward impaired carbohydrate metabolism.

Changes in traditional chronic disease risk factors over time and their relationship with leisure-time physical activity in people living with spinal cord injury

This study examined whether levels of chronic disease risk factors change over time, and whether leisure-time physical activity (LTPA) can explain any of the variation in those risk factors that change, in a sample of community-dwelling people living with spinal cord injury (SCI) in or near Hamilton, Ontario, Canada. LTPA was measured using the Physical Activity Recall Assessment for People with SCI at baseline (n = 76 adults with chronic (≥1 year) paraplegia or tetraplegia), at 6 months (n = 71) and at 18 months (n = 63). Body mass index, waist circumference at the lowest rib (WClowest rib) and iliac crest (WCiliac crest), fat mass, blood pressure, and biochemical data were collected at all 3 time points. Women’s BMI was higher at baseline (least square means (LSM) = 26.2 ± SE = 1.56 kg·m–2, p = 0.0004) and 6 months (25.9 ± 1.6, p = 0.0024) than at 18 months (22.1 ± 1.72). Men’s WClowest ribincreased from baseline (92.1 ± 1.87 cm) to 18 months (93.6 ± 1.87, p = 0.0253). Women who were active vs. inactive at baseline had a lower BMI at 6 months (23.1 ± 2.91 vs. 29.7 ± 2.52, p = 0.0957) and WCiliac crestat 6 months (82.8 ± 6.59 vs. 97.7 ± 5.10, p = 0.0818). Women who were active vs. inactive at 6 months had a lower WCiliac crestat 18 months (73.4 ± 14.3 vs. 102.5 ± 6.41, p = 0.0723). There was little change in traditional risk factors over 18 months. Future studies should extend beyond 18 months in a larger sample, and explore traditional vs. novel risk factors and onset of cardiovascular disease and diabetes in the SCI population.

Malnutrition in spinal cord injury: more than nutritional deficiency

Denervation of the spinal cord below the level of injury leads to complications producing malnutrition. Nutritional status affects mortality and pathology of injured subjects and it has been reported that two thirds of individuals enrolled in rehabilitation units are malnourished. Therefore, the aim should be either to maintain an optimal nutritional status, or supplement these subjects in order to overcome deficiencies in nutrients or prevent obesity. This paper reviews methods of nutritional assessment and describes the physiopathological mechanisms of malnutrition based on the assumption that spinal cord injured subjects need to receive adequate nutrition to promote optimal recovery, placing nutrition as a first line treatment and not an afterthought in the rehabilitation of spinal cord injury.

Alterations in mouse hypothalamic adipokine gene expression and leptin signaling following chronic spinal cord injury and with advanced age

Chronic spinal cord injury (SCI) results in an accelerated trajectory of several cardiovascular disease (CVD) risk factors and related aging characteristics, however the molecular mechanisms that are activated have not been explored. Adipokines and leptin signaling are known to play a critical role in neuro-endocrine regulation of energy metabolism, and are now implicated in central inflammatory processes associated with CVD. Here, we examine hypothalamic adipokine gene expression and leptin signaling in response to chronic spinal cord injury and with advanced age. We demonstrate significant changes in fasting-induced adipose factor (FIAF), resistin (Rstn), long-form leptin receptor (LepRb) and suppressor of cytokine-3 (SOCS3) gene expression following chronic SCI and with advanced age. LepRb and Jak2/stat3 signaling is significantly decreased and the leptin signaling inhibitor SOCS3 is significantly elevated with chronic SCI and advanced age. In addition, we investigate endoplasmic reticulum (ER) stress and activation of the uncoupled protein response (UPR) as a biological hallmark of leptin resistance. We observe the activation of the ER stress/UPR proteins IRE1, PERK, and eIF2alpha, demonstrating leptin resistance in chronic SCI and with advanced age. These findings provide evidence for adipokine-mediated inflammatory responses and leptin resistance as contributing to neuro-endocrine dysfunction and CVD risk following SCI and with advanced age. Understanding the underlying mechanisms contributing to SCI and age related CVD may provide insight that will help direct specific therapeutic interventions.

Spinal cord injury and physical activity: preservation of the body

SETTING

Spinal cord injury (SCI) causes devastating loss of function and can result in serious secondary complications. Although significant advances are being made to develop cellular and molecular therapies to promote regeneration, it is important to optimize physical interventions.

OBJECTIVES

The objective of this review was to examine the evidence for the effects of physical rehabilitation strategies on health and fitness, and maintenance of target systems below the level of injury (for example, muscle, bone, circulation).

RESULTS

Exercise appears to be a potent means of achieving these goals, using a variety of strategies.

CONCLUSION

Physical rehabilitation after SCI needs to move beyond the goal of maximizing independence to focus on maintenance of optimum health and fitness as well as maintenance of target system function below the level of injury. Issues requiring further investigation include identification of the optimum dosage of interventions to achieve specific goals, for example, prevention of muscle atrophy and osteoporosis, and development and validation of simple clinical measures to monitor the changes in body composition. Adoption of a classification system for physical interventions and standardized outcome measures would facilitate large-scale observational studies to identify the critical variables contributing to better outcomes.

Clinical assessment of obesity in persons with spinal cord injury: validity of waist circumference, body mass index, and anthropometric index

OBJECTIVE

To study the relationship of waist circumference (WC) and bioelectrical impedance analysis (BIA) and degree of agreement between anthropometric index (AI) and BIA, using BIA as a reference or 'gold standard'. The second objective is to study the relationship between body mass index (BMI) and BIA in subjects with spinal cord injury (SCI).

STUDY DESIGN

Comparative cross-sectional study.

SETTING

Convenience sample at outpatient clinic of spinal cord center.

OUTCOME MEASURES

Estimation of obesity was made in 23 men with motor complete paraplegia (>1 year post-injury). Bland and Altman statistics were used to define level of agreement between AI and BIA, Pearson's r to describe correlation between WC and BIA and BMI and BIA.

RESULTS

Good agreement between BIA and AI with a small systematic difference in fat mass (FM) (mean difference: -0.28%, Pearson's r: 0.91) was found. The correlation between WC and the BIA (% FM) was very high (Pearson's r: 0.83). The correlation between WC and BMI (% FM) was just over moderate (Pearson's r: 0.51).

CONCLUSION

AI seems to be a valid proxy measure to estimate obesity in males living with SCI. Measurement of obesity in persons with SCI based on WC is promising. BMI showed not to be valid to estimate obesity in persons with SCI.

Assessment of measures for abdominal adiposity in persons with spinal cord injury

Ultrasound may be a useful tool to assess abdominal adiposity, but it has not been validated in the spinal cord injury (SCI) population. This study evaluated associations between abdominal ultrasound and other methods to assess adiposity in 24 men with SCI and 20 able-bodied (AB) men. Waist (WC) and hip circumference (HC) and waist-to-hip ratio (WHR) were measured. Trunk (TRK%), android (A%) and waist fat (W%) were determined by dual energy x-ray absorptiometry (DXA); ultrasonography determined abdominal subcutaneous (SF) and visceral fat (VF). The SCI group had greater TRK% (40.0 ± 9.6 vs. 32.0 ± 10.3), W% (47.0 ± 9.7 vs. 40.6 ± 9.4), A% (43.0 ± 9.8 vs. 35.8 ± 10.6) and WHR (0.99 ± 0.1 vs. 0.92 ± 0.06) than the AB group. WC and WHR correlated with VF in the SCI group. These associations suggest that ultrasound may be a useful tool in clinical practice for the measurement of VF in weight loss programs and for the assessment of cardiometabolic disorders.

An evidence-based review of aging of the body systems following spinal cord injury

STUDY DESIGN

Systematic review.

OBJECTIVE

To systematically review evidence on aging of the body systems after spinal cord injury (SCI).

SETTING

Toronto, Ontario and Vancouver, British Columbia, Canada.

METHODS

Electronic databases (MEDLINE/PubMed, CINAHL, EMBASE and PsycINFO), were searched for studies published between 1980 and 2009. The search was augmented by reviewing the reference lists of relevant papers. Non-intervention studies that were longitudinal or cross-sectional with able-bodied controls that were at minimum matched on chronological age were included for review. Levels of evidence were assigned to the study design using a modified Sackett scale.

RESULTS

Of the 74 studies selected for inclusion, 16 were longitudinal in design. The hypothesis that SCI represents a model for premature aging is supported by a large proportion of level 5 evidence for the cardiovascular and endocrine systems, level 2, 4 and 5 evidence for the musculoskeletal system, and limited level 5 evidence for the immune system. Only a few level 4 and 5 studies for the respiratory system were found. The evidence on the genitourinary system, gastrointestinal system, and for skin and subcutaneous tissues provide level 4 and 5 evidence that premature aging may not be occurring. The evidence on the nervous system does not provide evidence of premature aging as a result of SCI.

CONCLUSIONS

Premature aging appears to occur in some systems after SCI. Additional longitudinal studies are required to confirm these findings.

Impact of bed rest on conduit artery remodeling: effect of exercise countermeasures

Physical inactivity is a potent stimulus for vascular remodeling, leading to a marked decrease in conduit artery diameter. However, little is known about the impact of physical inactivity on artery wall thickness or wall:lumen ratio or the potential of exercise countermeasures to modify artery wall thickness. The purpose of the study was to examine the impact of 60 days of bed rest, with or without exercise countermeasures, on carotid and superficial femoral artery wall thickness. Eighteen men were assigned to bed rest (second Berlin Bed Rest Study) and randomly allocated to control, resistive exercise, or resistive vibration exercise. Both exercise countermeasures were applied 3 times per week while the subjects were in the supine position on the bed. Sonography was used to examine baseline diameter and wall thickness of the carotid and femoral arteries. Bed rest decreased diameter of the superficial femoral artery (P=0.001) but not the carotid artery (P=0.29). Bed rest induced a significant increase in carotid and superficial femoral artery wall thickness (P=0.007 and 0.03) and wall:lumen ratio (P=0.009 and 0.001). Exercise prevented the increase in wall thickness of the carotid artery. In addition, exercise partly prevented the increased wall:lumen ratio in the superficial femoral artery. In conclusion, 8 weeks of bed rest resulted in approximately 20% increase in conduit artery wall thickness. Exercise countermeasures completely (carotid artery) or partly (superficial femoral artery) abolished the increase in wall thickness. These findings suggest that conduit artery wall thickness, a vascular characteristic associated previously with atherosclerosis, can rapidly adapt to physical inactivity and exercise in humans.

Impact of exercise training on oxidative stress in individuals with a spinal cord injury

Individuals with a spinal cord injury (SCI) have an increased cardiovascular risk. We hypothesize that (anti)oxidative imbalance is associated with the increased cardiovascular risk in SCI, while exercise can reverse this status. The aim of the study is to compare baseline levels of oxidative stress and antioxidative capacity between individuals with SCI and able-bodied (AB) subjects, and to assess acute and long-term effects of functional electrical stimulation (FES) exercise on oxidative stress and antioxidative capacity in SCI. Venous blood was taken from subjects with an SCI (n = 9) and age- and gender-matched AB subjects (n = 9) to examine oxidative stress through malondialdehyde (MDA) levels, while superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzyme levels represented anti-oxidative capacity. Subsequently, subjects with an SCI performed an 8-week FES exercise training period. Blood was taken before and after the first exercise bout and after the last FES session to examine the acute and chronic effect of FES exercise, respectively. Baseline levels of MDA, SOD and GPx were not different between individuals with SCI and AB subjects. SCI demonstrated a correlation between initial fitness level and MDA (R = -0.83, P = 0.05). MDA, SOD and GPx levels were neither altered by a single FES exercise bout nor by 8 weeks FES training. In conclusion, although individuals with an SCI demonstrate a preserved (anti)oxidative status, the correlation between fitness level and (anti)oxidative balance suggests that higher fitness levels are related to improved (anti)oxidative status in SCI. Nonetheless, the FES exercise stimulus was insufficient to acutely or chronically change (anti)oxidative status in individuals with an SCI.

Impact of inactivity and exercise on the vasculature in humans

The effects of inactivity and exercise training on established and novel cardiovascular risk factors are relatively modest and do not account for the impact of inactivity and exercise on vascular risk. We examine evidence that inactivity and exercise have direct effects on both vasculature function and structure in humans. Physical deconditioning is associated with enhanced vasoconstrictor tone and has profound and rapid effects on arterial remodelling in both large and smaller arteries. Evidence for an effect of deconditioning on vasodilator function is less consistent. Studies of the impact of exercise training suggest that both functional and structural remodelling adaptations occur and that the magnitude and time-course of these changes depends upon training duration and intensity and the vessel beds involved. Inactivity and exercise have direct "vascular deconditioning and conditioning" effects which likely modify cardiovascular risk.