Liver Adiposity and Metabolic Profile in Individuals with Chronic Spinal Cord Injury

Risk of adverse cardiovascular events following spinal cord injury in patients with osteoporosis: Real-world evidence

Introduction

Spinal cord injury (SCI) is associated with increased cardiovascular risks, and cardiovascular disease (CVD) remains a leading cause of death for individuals with SCI. Osteoporosis, a condition associated with SCI, has been linked to CVD. However, the cardiovascular risk profile of individuals with SCI with osteoporosis remains unclear.

Methods

We conducted a retrospective cohort study by using data from the TriNetX Research Network. We included adults with osteoporosis with or without a diagnosis of SCI between 2015 and 2020: case (SCI group, N = 7,308) and control (non-SCI group, N = 843,235) cohorts. Propensity score matching was performed to balance baseline characteristics between the cohorts (N = 7,296 in each group). A Cox regression model was employed to estimate the hazard ratio (HR) for the primary outcomes: the development of acute myocardial infarction (AMI), atrial fibrillation (AF), or heart failure (HF).

Results

Individuals with SCI with osteoporosis have a significantly higher risk of cardiovascular events (HR: 1.15, 95 % confidence interval [CI]: 1.08-1.22)-including AMI (HR: 1.17 95 % CI: 1.02-1.33), AF (HR: 1.14, 95 % CI: 1.04-1.24), and HF (HR: 1.14, 95 % CI: 1.05-1.24)-than do those without SCI. Furthermore, mortality risk is higher in individuals with SCI, particularly those with pathological fracture. Subgroup analyses based on sex and age supported these findings.

Conclusion

The complex interplay between SCI, osteoporosis, and cardiovascular health underscores the requirement for comprehensive management strategies for individuals with SCI who also have osteoporosis.

Spinal cord injury induces transient activation of hepatic stellate cells in rat liver

Spinal cord injury (SCI) causes abnormal liver function, the development of metabolic dysfunction-associated steatotic liver disease features and metabolic impairment in patients. Experimental models also demonstrate acute and chronic changes in the liver that may, in turn, affect SCI recovery. These changes have collectively been proposed to contribute to the development of a SCI-induced metabolic dysfunction-associated steatohepatitis (MASH). However, none of the existent studies have focused on hepatic stellate cells (HSCs), liver resident cells that are the primary drivers of collagen deposition and fibrosis following sustained liver damage. Here, we describe the transient activation of HSCs after a thoracic contusion in rats, considered a clinically relevant model of experimental SCI. We studied HSC during the time course of SCI, from 1 to 45 days post injury. We found a transient activation of HSCs after SCI, beginning with the acute downregulation of Glial Fibrillar Acidic Protein 1dpi. This is followed by a morphological and phenotypical transformation into alpha-smooth muscle actin (ACTA2/SMA) immunoreactive myofibroblast-like cells, peaking at 14 days post-injury and returning to control-like levels at later timepoints (45 days post-injury). These changes are not accompanied by fibrosis development but collagen deposition in peri-portal areas is observed at 45 days.

Exploring lifestyle components and associated factors in newly injured individuals with spinal cord injury

STUDY DESIGN

Cross-sectional analysis from the Inception Cohort of the Swiss Spinal Cord Injury Study (SwiSCI).

OBJECTIVES

To describe five lifestyle components in newly injured individuals with spinal cord injury (SCI), explore co-occurrence of these components, and identify associated personal and clinical factors.

SETTINGS

Initial rehabilitation stay following traumatic and non-traumatic SCI.

METHODS

Lifestyle components including overweight/obesity, low diet score, physical inactivity, smoking, and alcohol consumption were used independently and to calculate a composite lifestyle score. Analyses were conducted using descriptive statistics, co-occurrence analysis, and multivariate logistic regression.

RESULTS

We included 251 individuals, of whom 77.7% were male, 73.7% suffered from traumatic SCI, and 59.8% had paraplegia. The median age was 51 years (IQR 36-64). Approximately twelve weeks after the injury, more than two-thirds of the study population met the criteria for overweight/obesity, and consumed insufficient amounts of fruits and vegetables, and excessive amounts of meat. Alcohol was consumed by 85.3% of individuals, and 26.8% were current smokers. Almost all study participants met the physical activity guidelines (90 min of moderate to strenuous activity physical activity per week). One-quarter of study participants experienced the co-occurrence of overweight/obesity, low diet score and alcohol consumption. Female sex, younger age and higher education were associated with healthier lifestyle components.

CONCLUSION

Despite methodological limitations, this study underscores the complexities of healthy lifestyle adherence among individuals newly injured with SCI. It highlights the necessity of improving and implementing screening strategies throughout the continuum of SCI care as early as possible following the trauma.

Neurogenic Aging After Spinal Cord Injury: Highlighting the Unique Characteristics of Aging After Spinal Cord Injury

Emanating from several decades of study into the effects of the aging process after spinal cord injury (SCI), "accelerated aging" has become a common expression as the SCI accelerates the onset of age-related pathologies. However, the aging process follows a distinct trajectory, characterized by unique patterns of decline that differ from those observed in the general population without SCI. Aging brings significant changes to muscles, bones, and hormones, impacting overall physical function. Muscle mass and strength begin to decrease with a reduction in muscle fibers and impaired repair mechanisms. Bones become susceptible to fractures as bone density decreases. Hormonal changes combined with decreased physical activity accelerate the reduction of muscle mass and increase in body fat. Muscle atrophy and skeletal muscle fiber type transformation occur rapidly and in a unique pattern after SCI. Bone loss develops more rapidly and results in an increased risk of fractures in body regions unique to individuals with SCI. Other factors, such as excessive adiposity, decreased testosterone and human growth hormone, and increased systemic inflammation, contribute to a higher risk of neuropathically driven obesity, dyslipidemia, glucose intolerance, insulin resistance, and increasing cardiovascular disease risk. Cardiorespiratory changes after SCI result in lower exercise heart rates, decreased oxygenation, and mitochondrial dysfunction. While it is important to acknowledge the accelerated aging processes after SCI, it is essential to recognize the distinct differences in the aging process between individuals without physical disabilities and those with SCI. These differences, influenced by neuropathology, indicate that it may be more accurate to describe the aging process in individuals with chronic SCI as neurogenic accelerated aging (NAA). Research should continue to address conditions associated with NAA and how to ameliorate the accelerated rate of premature age-related conditions. This review focuses on the NAA processes and the differences between them and the aging process in those without SCI. Recommendations are provided to help slow the development of premature aging conditions.

Increased Risk of Myocardial Infarction, Heart Failure, and Atrial Fibrillation After Spinal Cord Injury

BACKGROUND

Heart diseases are a growing concern for the spinal cord injury (SCI) population.

OBJECTIVES

This study aims to compare the incidence of heart diseases between SCI survivors and the general non-SCI population.

METHODS

We identified 5,083 SCI survivors and 1:3 age- and sex-matched non-SCI controls. Study outcomes were myocardial infarction (MI), heart failure (HF), and atrial fibrillation (AF). The cohort was followed up from the index date (diagnosis date for SCI or corresponding date for matched controls) until 2019.

RESULTS

SCI survivors showed a higher risk for MI (adjusted HR [aHR]: 2.41; 95% CI: 1.93-3.00), HF (aHR: 2.24; 95% CI: 1.95-2.56), and AF (aHR: 1.84; 95% CI: 1.49-2.28) compared to controls. The risks were further increased for those who were registered in the National Disability Registry within 1 year from the index date (SCI survivors with disability): SCI survivors with severe disability had the highest risks of MI (aHR: 3.74; 95% CI: 2.43-5.76), HF (aHR: 3.96; 95% CI: 3.05-5.14), and AF (aHR: 3.32; 95% CI: 2.18-5.05). Cervical and lumbar SCI survivors had an increased risk of heart disease regardless of disability compared to matched controls; these risks were slightly higher in those with disability. Thoracic SCI survivors with disability had significantly increased risk of heart disease compared to matched controls.

CONCLUSIONS

SCI survivors at all levels were at significantly greater risk for heart disease than non-SCI controls, particularly those with severe disability. Clinicians must be aware of the importance of heart disease in SCI survivors.

System failure: Systemic inflammation following spinal cord injury

Spinal cord injury (SCI) affects hundreds of thousands of people in the United States, and while some effects of the injury are broadly recognized (deficits to locomotion, fine motor control, and quality of life), the systemic consequences of SCI are less well-known. The spinal cord regulates systemic immunological and visceral functions; this control is often disrupted by the injury, resulting in viscera including the gut, spleen, liver, bone marrow, and kidneys experiencing local tissue inflammation and physiological dysfunction. The extent of pathology depends on the injury level, severity, and time post-injury. In this review, we describe immunological and metabolic consequences of SCI across several organs. Since infection and metabolic disorders are primary reasons for reduced lifespan after SCI, it is imperative that research continues to focus on these deleterious aspects of SCI to improve life span and quality of life for individuals with SCI.

The Physiology of Neurogenic Obesity: Lessons from Spinal Cord Injury Research

BACKGROUND

A spinal cord injury (SCI) from trauma or disease impairs sensorimotor pathways in somatic and autonomic divisions of the nervous system, affecting multiple body systems. Improved medical practices have increased survivability and life expectancy after SCI, allowing for the development of extensive metabolic comorbidities and profound changes in body composition that culminate in prevalent obesity.

SUMMARY

Obesity is the most common cardiometabolic component risk in people living with SCI, with a diagnostic body mass index cutoff of 22 kg/m2 to account for a phenotype of high adiposity and low lean mass. The metameric organization of specific divisions of the nervous system results in level-dependent pathology, with resulting sympathetic decentralization altering physiological functions such as lipolysis, hepatic lipoprotein metabolism, dietary fat absorption, and neuroendocrine signaling. In this manner, SCI provides a unique opportunity to study in vivo the "neurogenic" components of certain pathologies that otherwise are not readily observable in other populations. We discuss the unique physiology of neurogenic obesity after SCI, including the altered functions mentioned above as well as structural changes such as reduced skeletal muscle and bone mass and increased lipid deposition in the adipose tissue, skeletal muscle, bone marrow, and liver.

KEY MESSAGE

The study of neurogenic obesity after SCI gives us a unique neurological perspective on the physiology of obesity. The lessons learned from this field can guide future research and advancements to inform the study of obesity in persons with and without SCI.

The use of alkaline phosphatase as a bone turnover marker after spinal cord injury: A scoping review of human and animal studies

BACKGROUND

Serum alkaline phosphatase (ALP) is measured as an indicator of bone or liver disease. Bone-specific alkaline phosphatase (B-ALP) is an isoform of ALP found in the bone tissue which can predict fractures and heterotopic ossification.

OBJECTIVE

The aim of this scoping review was to explore the current use of ALP and B-ALP in studies using humans or animal models of SCI, and to identify ways to advance future research using ALP and B-ALP as a bone marker after SCI.

RESULTS

HUMAN STUDIES: 42 studies were included. The evidence regarding changes or differences in ALP levels in individuals with SCI compared to controls is conflicting. For example, a negative correlation between B-ALP and total femur BMD was observed in only one of three studies examining the association. B-ALP seemed to increase after administration of teriparatide, and to decrease after treatment with denosumab. The effects of exercise on ALP and B-ALP levels are heterogeneous and depend on the type of exercise performed. ANIMAL STUDIES: 11 studies were included. There is uncertainty regarding the response of ALP or B-ALP levels after SCI; levels increased after some interventions, including vibration protocols, curcumin supplementation, cycles in electromagnetic field or hyperbaric chamber. Calcitonin or bisphosphonate administration did not affect ALP levels.

CONCLUSION

Researchers are encouraged to measure the bone-specific isoform of ALP rather than total ALP in future studies in humans of animal models of SCI.

Body composition and metabolic parameters in men with chronic traumatic paraplegia - A pilot study from India

OBJECTIVE

To study body composition, measures of insulin resistance and dyslipidemia in Indian men with paraplegia as compared to age and body mass index (BMI) matched able-bodied men.

DESIGN

Cross sectional study.

SETTING

Departments of Physical Medicine and Rehabilitation and Endocrinology.

PARTICIPANTS

Males aged 18-45 years with chronic traumatic paraplegia versus age and BMI-matched able-bodied men.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Measures of body composition such as total body fat, lean mass, regional adiposity using dual energy x-ray absorptiometry (DXA), metabolic profile and insulin resistance.

RESULTS

Subjects with paraplegia (n = 43), compared to controls (n = 36), had higher %Fat mass (FM) (25.5 (21.2-28.9) vs 20.2 (15.9-22.2); P < 0.01), lower trunk to leg ratio (0.66 (0.51-0.73) vs 0.87 (0.72-0.94); P < 0.01), lower lean mass index (14.38 (2.57) vs 17.80 (2.34); P < 0.01) and lower appendicular lean mass index (5.81 ± 1.26 vs 8.17 ± 1.12; P < 0.01). Fasting blood glucose (mg/dl) was higher (89.0(81.5-96.5) vs 80.0 (74.5-88.2); P < 0.01), Homeostasis model assessment of insulin resistance was higher (1.33 (1.03-2.12) vs 0.94 (0.52-1.78); P = 0.02), Quantitative insulin sensitivity check index (QUICKI) was lower (0.36 ± 0.04 vs 0.38 ± 0.05; P = 0.02) and HDL-C was lower (33.00 (30.00-42.75) vs 38.50 (33.00-43.25); P < 0.02) in cases compared to controls. QUICKI correlated positively with HDL-C and negatively with %FM, estimated VAT volume and TG. Trunk to leg ratio correlated positively with TG even after controlling for %FM.

CONCLUSION

Men with chronic paraplegia had lower lean mass, higher total and regional fat mass, increased insulin resistance and low HDL-C when compared with BMI-matched able-bodied controls. Both total and regional adiposity correlated with poor metabolic profile.

The Diagnosis and Management of Cardiometabolic Risk and Cardiometabolic Syndrome after Spinal Cord Injury

Individuals with spinal cord injuries (SCI) commonly present with component risk factors for cardiometabolic risk and combined risk factors for cardiometabolic syndrome (CMS). These primary risk factors include obesity, dyslipidemia, dysglycemia/insulin resistance, and hypertension. Commonly referred to as "silent killers", cardiometabolic risk and CMS increase the threat of cardiovascular disease, a leading cause of death after SCI. This narrative review will examine current data and the etiopathogenesis of cardiometabolic risk, CMS, and cardiovascular disease associated with SCI, focusing on pivotal research on cardiometabolic sequelae from the last five years. The review will also provide current diagnosis and surveillance criteria for cardiometabolic disorders after SCI, a novel obesity classification system based on percent total body fat, and lifestyle management strategies to improve cardiometabolic health.

Physical activity and cardiometabolic risk factors in individuals with spinal cord injury: a systematic review and meta-analysis

Physical inactivity in individuals with spinal cord injury (SCI) has been suggested to be an important determinant of increased cardiometabolic disease (CMD) risk. However, it remains unclear whether physically active SCI individuals as compared to inactive or less active individuals have truly better cardiometabolic risk profile. We aimed to systematically review and quantify the association between engagement in regular physical activity and/or exercise interventions and CMD risk factors in individuals with SCI. Four medical databases were searched and studies were included if they were clinical trials or observational studies conducted in adult individuals with SCI and provided information of interest. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was applied to rate the certainty of evidence. Of 5816 unique citations, 11 randomized clinical trials, 3 non-randomized trial and 32 cross-sectional studies comprising more than 5500 SCI individuals were included in the systematic review. In meta-analysis of RCTs and based on evidence of moderate certainty, physical activity in comparison to control intervention was associated with: (i) better glucose homeostasis profile [WMD of glucose, insulin and Assessment of Insulin Resistance (HOMA-IR) were - 3.26 mg/dl (95% CI - 5.12 to - 1.39), - 3.19 μU/ml (95% CI - 3.96 to - 2.43)] and - 0.47 (95% CI - 0.60 to - 0.35), respectively], and (ii) improved cardiorespiratory fitness [WMD of relative and absolute oxygen uptake relative (VO2) were 4.53 ml/kg/min (95% CI 3.11, 5.96) and 0.26 L/min (95% CI 0.21, 0.32) respectively]. No differences were observed in blood pressure, heart rate and lipids (based on evidence of low/moderate certainty). In meta-analysis of cross-sectional studies and based on the evidence of very low to low certainty, glucose [WMD - 3.25 mg/dl (95% CI - 5.36, - 1.14)], insulin [- 2.12 μU/ml (95% CI - 4.21 to - 0.03)] and total cholesterol [WMD - 6.72 mg/dl (95% CI - 13.09, - 0.34)] were lower and HDL [WMD 3.86 mg/dl (95% CI 0.66, 7.05)] and catalase [0.07 UgHb-1 (95% CI 0.03, 0.11)] were higher in physically active SCI individuals in comparison to reference groups. Based on limited number of cross-sectional studies, better parameters of systolic and diastolic cardiac function and lower carotid intima media thickness were found in physically active groups. Methodologically sound clinical trials and prospective observational studies are required to further elaborate the impact of different physical activity prescriptions alone or in combination with other life-style interventions on CMD risk factors in SCI individuals.

Metabolomic Profiling Reveals Protective Effects and Mechanisms of Sea Buckthorn Sterol against Carbon Tetrachloride-Induced Acute Liver Injury in Rats

The present study was designed to examine the efficacy and protection mechanisms of sea buckthorn sterol (SBS) against acute liver injury induced by carbon tetrachloride (CCl₄) in rats. Five-week-old male Sprague-Dawley (SD) rats were divided into six groups and fed with saline (Group BG), 50% CCl₄ (Group MG), or bifendate 200 mg/kg (Group DDB), or treated with low-dose (Group LD), medium-dose (Group MD), or high-dose (Group HD) SBS. This study, for the first time, observed the protection of SBS against CCl₄-induced liver injury in rats and its underlying mechanisms. Investigation of enzyme activities showed that SBS-fed rats exhibited a significant alleviation of inflammatory lesions, as evidenced by the decrease in cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and gamma-glutamyl transpeptidase (γ-GT). In addition, compared to the MG group, the increased indices (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), total antioxidant capacity (T-AOC), and total protein (TP)) of lipid peroxidation and decreased malondialdehyde (MDA) in liver tissues of SBS-treated groups showed the anti-lipid peroxidation effects of SBS. Using the wide range of targeted technologies and a combination of means (UPLC-MS/MS detection platform, self-built database, and multivariate statistical analysis), the addition of SBS was found to restore the expression of metabolic pathways (e.g., L-malic acid, N-acetyl-aspartic acid, N-acetyl-l-alanine, etc.) in rats, which means that the metabolic damage induced by CCl₄ was alleviated. Furthermore, transcriptomics was employed to analyze and compare gene expression levels of different groups. It showed that the expressions of genes (Cyp1a1, Noct, and TUBB6) related to liver injury were regulated by SBS. In conclusion, SBS exhibited protective effects against CCl₄-induced liver injury in rats. The liver protection mechanism of SBS is probably related to the regulation of metabolic disorders, anti-lipid peroxidation, and inhibition of the inflammatory response.

Evaluation of the Cardiometabolic Disorders after Spinal Cord Injury in Mice

Changes in cardiometabolic functions contribute to increased morbidity and mortality after chronic spinal cord injury. Despite many advancements in discovering SCI-induced pathologies, the cardiometabolic risks and divergences in severity-related responses have yet to be elucidated. Here, we examined the effects of SCI severity on functional recovery and cardiometabolic functions following moderate (50 kdyn) and severe (75 kdyn) contusions in the thoracic-8 (T8) vertebrae in mice using imaging, morphometric, and molecular analyses. Both severities reduced hindlimbs motor functions, body weight (g), and total body fat (%) at all-time points up to 20 weeks post-injury (PI), while only severe SCI reduced the total body lean (%). Severe SCI increased liver echogenicity starting from 12 weeks PI, with an increase in liver fibrosis in both moderate and severe SCI. Severe SCI mice showed a significant reduction in left ventricular internal diameters and LV volume at 20 weeks PI, associated with increased LV ejection fraction as well as cardiac fibrosis. These cardiometabolic dysfunctions were accompanied by changes in the inflammation profile, varying with the severity of the injury, but not in the lipid profile nor cardiac or hepatic tyrosine hydroxylase innervation changes, suggesting that systemic inflammation may be involved in these SCI-induced health complications.

Comparison of Various Indices in Identifying Insulin Resistance and Diabetes in Chronic Spinal Cord Injury

The purpose of this screening and diagnostic study was to examine the accord among indices of glucose metabolism, including the Homeostatic Model Assessment for Insulin Resistance (HOMA), HOMA2, Matsuda Index, Quantitative Insulin-sensitivity Check Index (QUICKI), hemoglobin A1C (HbA1C), and fasting plasma glucose (FPG) against intravenous glucose tolerance test-measured insulin sensitivity (Si) in individuals with chronic motor complete SCI. Persons with chronic (≥12-months post-injury) SCI (n = 29; 79% men; age 42.2 ± 11.4; body mass index 28.6 ± 6.4 kg/m2; C4-T10) were included. Measures were compared using adjusted R2 from linear regression models with Akaike information criterion (AIC, a measure of error). QUICKI had the greatest agreement with Si (adjusted R2 = 0.463, AIC = 91.1, p = 0.0001), followed by HOMA (adjusted R2 = 0.378, AIC = 95.4, p = 0.0008), HOMA2 (adjusted R2 = 0.256, AIC = 99.7, p = 0.0030), and the Matsuda Index (adjusted R2 = 0.356, AIC = 95.5, p = 0.0004). FPG (adjusted R2 = 0.056, AIC = 107.5, p = 0.1799) and HbA1C (adjusted R2 = 0.1, AIC = 106.1, p = 0.0975) had poor agreement with Si. While HbA1C and FPG are commonly used for evaluating disorders of glucose metabolism, QUICKI demonstrates the best accord with Si compared to the other measures.

Body Composition According to Spinal Cord Injury Level: A Systematic Review and Meta-Analysis

The level of injury is linked with biochemical alterations and limitations in physical activity among individuals with spinal cord injury (SCI), which are crucial determinants of body composition. We searched five electronic databases from inception until 22 July 2021. The pooled effect estimates were computed using random-effects models, and heterogeneity was calculated using I² statistics and the chi-squared test. Study quality was assessed using the Newcastle–Ottawa Scale. We pooled 40 studies comprising 4872 individuals with SCI (3991 males, 825 females, and 56 sex-unknown) in addition to chronic SCI (median injury duration 12.3 y, IQR 8.03–14.8). Individuals with tetraplegia had a higher fat percentage (weighted mean difference (WMD) 1.9%, 95% CI 0.6, 3.1) and lower lean mass (WMD −3.0 kg, 95% CI −5.9, −0.2) compared to those with paraplegia. Those with tetraplegia also had higher indicators of central adiposity (WMD, visceral adipose tissue area 0.24 dm² 95% CI 0.05, 0.43 and volume 1.05 L 95% CI 0.14, 1.95), whereas body mass index was lower in individuals with tetraplegia than paraplegia (WMD −0.9 kg/mg², 95% CI −1.4, −0.5). Sex, age, and injury characteristics were observed to be sources of heterogeneity. Thus, individuals with tetraplegia have higher fat composition compared to paraplegia. Anthropometric measures, such as body mass index, may be inaccurate in describing adiposity in SCI individuals.

The Role of Lipids, Lipid Metabolism and Ectopic Lipid Accumulation in Axon Growth, Regeneration and Repair after CNS Injury and Disease

Axons in the adult mammalian nervous system can extend over formidable distances, up to one meter or more in humans. During development, axonal and dendritic growth requires continuous addition of new membrane. Of the three major kinds of membrane lipids, phospholipids are the most abundant in all cell membranes, including neurons. Not only immature axons, but also severed axons in the adult require large amounts of lipids for axon regeneration to occur. Lipids also serve as energy storage, signaling molecules and they contribute to tissue physiology, as demonstrated by a variety of metabolic disorders in which harmful amounts of lipids accumulate in various tissues through the body. Detrimental changes in lipid metabolism and excess accumulation of lipids contribute to a lack of axon regeneration, poor neurological outcome and complications after a variety of central nervous system (CNS) trauma including brain and spinal cord injury. Recent evidence indicates that rewiring lipid metabolism can be manipulated for therapeutic gain, as it favors conditions for axon regeneration and CNS repair. Here, we review the role of lipids, lipid metabolism and ectopic lipid accumulation in axon growth, regeneration and CNS repair. In addition, we outline molecular and pharmacological strategies to fine-tune lipid composition and energy metabolism in neurons and non-neuronal cells that can be exploited to improve neurological recovery after CNS trauma and disease.

Acute exercise improves glucose effectiveness but not insulin sensitivity in paraplegia

PURPOSE

To determine the effect of a single session of arm crank ergometry (ACE) exercise on carbohydrate metabolism immediately and 24 h after the exercise bout in paraplegia and able-bodied controls (ABC).

METHODS

Paraplegia (n = 11; 91% male; age 34.8 ± 11.4 years) and ABC (n = 6; 67% male; age 28.7 ± 11.9 years) underwent 45 min of ACE exercise at 75% VO_2Peak. Glucose effectiveness (Sg) and insulin sensitivity (Si) were assessed. Data were analyzed with two-way mixed analysis of variance and Wilcoxon rank-sum or signed-rank post hoc test.

RESULTS

VO_2Peak was lower in paraplegia versus ABC (22.3 ± 3.99 vs. 30.8 ± 2.9 ml/kg/min, p = 0.003). Si was lower paraplegia vs. ABC immediately following exercise (3.28 ± 1.6 vs. 5.30 ± 1.2 min^-1/[µU/mL^-1]x10^-4, p = 0.023). In paraplegia, Sg was higher immediately after exercise than baseline (B: 0.021 ± 0.01 vs. I: 0.026 ± 0.01 min^-1, p = 0.037). Twenty-four hours after exercise, Sg was lower than immediately following exercise (I: 0.026 ± 0.01 vs. 24: 0.017 ± 0.01 min^-1, p = 0.001), but not different than baseline in paraplegia (B: 0.021 ± 0.01 vs. 24: 0.017 ± 0.01 min^-1, p = 0.216). In the ABC group, Sg was not different at all timepoints (p > 0.05). Si did not differ at all timepoints (p > 0.05).

CONCLUSION

A single bout of ACE at 75% VO_2Peak helped to acutely control glucose metabolism in those with paraplegia by increasing Sg by nearly 27%; however, this was not sustained past 24-hours. These data provide support for regular exercise engagement.Implications for RehabilitationDisorders of glucose metabolism have been reported at a greater prevalence in persons with spinal cord injury.A single bout of arm crank ergometry exercise at 75% VO_2Peak helped to acutely control glucose metabolism persons with paraplegia; however, this was not sustained past 24 h.These data provide support for regular exercise engagement in persons with paraplegia.

Role of exercise on visceral adiposity after spinal cord injury: a cardiometabolic risk factor

PURPOSE

Visceral adipose tissue (VAT) is associated with cardiometabolic disease risk in able-bodied (AB) populations. However, the underlying mechanisms of VAT-induced disease risk are unknown in persons with spinal cord injury (SCI). Potential mechanisms of VAT-induced cardiometabolic dysfunction in persons with SCI include systemic inflammation, liver adiposity, mitochondrial dysfunction, and anabolic deficiency. Moreover, how exercise interventions impact these mechanisms associated with VAT-induced cardiometabolic dysfunction are still being explored.

METHODS

A search for relevant scientific literature about the effects of exercise on VAT and cardiometabolic health was conducted on the PubMed database. Literature from reference lists was also included when appropriate.

RESULTS

Both aerobic and resistance exercise training beneficially impact health and VAT mass via improving mitochondrial function, glucose effectiveness, and inflammatory signaling in SCI and AB populations. Specifically, aerobic exercise appears to also modulate cellular senescence in AB populations and animal models, while resistance exercise seems to augment anabolic signaling in persons with SCI.

CONCLUSIONS

The current evidence supports regular engagement in exercise to reduce VAT mass and the adverse effects on cardiometabolic health in persons with SCI. Future research is needed to further elucidate the precise mechanisms by which VAT negatively impacts health following SCI. This will likely facilitate the development of rehabilitation protocols that target VAT reduction in persons with SCI.

Neurogenic Obesity-Induced Insulin Resistance and Type 2 Diabetes Mellitus in Chronic Spinal Cord Injury

The population with SCI is at a significant risk for both insulin resistance and type 2 diabetes mellitus (T2DM) secondary to neurogenic obesity. The prevalence of insulin resistance and T2DM in persons with SCI suggests that disorders of carbohydrate metabolism are at epidemic proportions within the population. However, the true frequency of such disorders may be underestimated because biomarkers of insulin resistance and T2DM used from the population without SCI remain nonspecific and may in fact fail to identify true cases that would benefit from intervention. Furthermore, diet and exercise have been used to help mitigate neurogenic obesity, but results on disorders of carbohydrate metabolism remain inconsistent, likely because of the various ways carbohydrate metabolism is assessed. The objective of this article is to review current literature on the prevalence and likely mechanisms driving insulin resistance and T2DM in persons with SCI. This article also explores the various assessments and diagnostic criteria used for insulin resistance and T2DM and briefly discusses the effects of exercise and/or diet to mitigate disorders of carbohydrate metabolism brought on by neurogenic obesity.

Anthropometric Prediction of Visceral Adiposity in Persons With Spinal Cord Injury

Over two-thirds of persons with spinal cord injury (SCI) experience neurogenic obesity-induced cardiometabolic syndrome (CMS) and other chronic comorbidities. Obesity is likely to impede social and recreational activities, impact quality of life, and impose additional socioeconomic burdens on persons with SCI. Advances in imaging technology facilitate the mapping of adiposity and its association with the cardiometabolic profile after SCI. Central adiposity or central obesity is characterized by increased waist (WC) and abdominal circumferences (AC) as well as visceral adipose tissue (VAT). A number of studies, while relying on expensive imaging techniques, have reported direct associations of both central obesity and VAT in imposing significant health risks after SCI. The mechanistic role of central obesity on cardiometabolic heath in persons with SCI has yet to be identified, despite the knowledge that it has been designated as an independent risk factor for cardiometabolic dysfunction and premature mortality in other clinical populations. In persons with SCI, the distribution of adipose tissue has been suggested to be a function of sex, level of injury, and age. To date, there is no SCI-specific WC or AC cutoff value to provide anthropometric prediction of VAT and diagnostic capability of persons at risk for central obesity, CMS, and cardiovascular disease after SCI. The purpose of the current review is to summarize the factors contributing to visceral adiposity in persons with SCI and to develop an SCI-specific anthropometric prediction equation for this population. Furthermore, a proposed WC cutoff will be discussed as a surrogate index for central obesity, CMS, and cardiovascular disorders after SCI.

Energy Expenditure, Cardiorespiratory Fitness, and Body Composition Following Arm Cycling or Functional Electrical Stimulation Exercises in Spinal Cord Injury: A 16-Week Randomized Controlled Trial

Background: Physical deconditioning and inactivity following spinal cord injury (SCI) are associated with multiple cardiometabolic risks. To mitigate cardiometabolic risk, exercise is recommended, but it is poorly established whether arm cycling exercise (ACE) or functional electrical stimulation (FES) leg cycling yields superior benefits. Objectives: To determine the adaptations of 16 weeks of FES cycling and ACE on exercise energy expenditure (EEE), cardiorespiratory fitness (CRF), and obesity after SCI. Methods: Thirteen physically untrained individuals were randomly assigned to FES (n = 6) or ACE (n = 7) exercise 5 days/week for 16 weeks. Pre- and post-intervention EEE, peak oxygen consumption (absolute and relative VO2Peak), and work were assessed using indirect calorimetry, while body composition was measured by dual-energy x-ray absorptiometry. Results: Main effects were found for peak power (p < .001), absolute (p = .046) and relative (p = .042) VO2Peak, and peak work (p = .013). Compared to baseline, the ACE group increased in EEE (+85%, p = .002), peak power (+307%, p < .001), VO2Peak (absolute +21%, relative +22%, p ≤ .024), peak work (19% increase, p = .003), and total body fat decreased (-6%, p = .05). The FES group showed a decrease in percentage body fat mass (-5%, p = .008). The ACE group had higher EEE (p = .008), peak power (p < .001), and relative VO2Peak (p = .025) compared to postintervention values in the FES group. Conclusion: In the current study, ACE induced greater increases in EEE and CRF, whereas ACE and FES showed similar results on body fat. Exercise promotional efforts targeting persons with SCI should use both FES and ACE to reduce sedentary behavior and to optimize different health parameters after SCI.

Effects of a High-Fat Diet on Tissue Mass, Bone, and Glucose Tolerance after Chronic Complete Spinal Cord Transection in Male Mice

Spinal cord injury (SCI) is associated with obesity and is a risk factor for type 2 diabetes mellitus (T2DM). Immobilization, muscle atrophy, obesity, and loss of sympathetic innervation to the liver are believed to contribute to risks of these abnormalities. Systematic study of the mechanisms underlying SCI-induced metabolic disorders has been limited by a lack of animal models of insulin resistance following SCI. Therefore, the effects of a high-fat diet (HFD), which causes weight gain and glucose intolerance in neurologically intact mice, was tested in mice that had undergone a spinal cord transection at thoracic vertebra 10 (T10) or a sham-transection. At 84 days after surgery, Sham-HFD and SCI-HFD mice showed impaired intraperitoneal glucose tolerance when compared with Sham control (Sham-Con) or SCI control (SCI-Con) mice fed a standard control chow. Glucose tolerance in SCI-Con mice was comparable to that of Sham-Con mice. The mass of paralyzed skeletal muscle, liver, and epididymal, inguinal, and omental fat deposits were lower in SCI versus Sham groups, with lower liver mass present in SCI-HFD versus SCI-Con animals. SCI also produced sublesional bone loss, with no differences between SCI-Con and SCI-HFD groups. The results suggest that administration of a HFD to mice after SCI may provide a model to better understand mechanisms leading to insulin resistance post-SCI, as well as an approach to study pathogenesis of glucose intolerance that is independent of obesity.

The spinal cord-gut-immune axis as a master regulator of health and neurological function after spinal cord injury

Most spinal cord injury (SCI) research programs focus only on the injured spinal cord with the goal of restoring locomotor function by overcoming mechanisms of cell death or axon regeneration failure. Given the importance of the spinal cord as a locomotor control center and the public perception that paralysis is the defining feature of SCI, this "spinal-centric" focus is logical. Unfortunately, such a focus likely will not yield new discoveries that reverse other devastating consequences of SCI including cardiovascular and metabolic disease, bladder/bowel dysfunction and infection. The current review considers how SCI changes the physiological interplay between the spinal cord, the gut and the immune system. A suspected culprit in causing many of the pathological manifestations of impaired spinal cord-gut-immune axis homeostasis is the gut microbiota. After SCI, the composition of the gut microbiota changes, creating a chronic state of gut "dysbiosis". To date, much of what we know about gut dysbiosis was learned from 16S-based taxonomic profiling studies that reveal changes in the composition and abundance of various bacteria. However, this approach has limitations and creates taxonomic "blindspots". Notably, only bacteria can be analyzed. Thus, in this review we also discuss how the application of emerging sequencing technologies can improve our understanding of how the broader ecosystem in the gut is affected by SCI. Specifically, metagenomics will provide researchers with a more comprehensive look at post-injury changes in the gut virome (and mycome). Metagenomics also allows changes in microbe population dynamics to be linked to specific microbial functions that can affect the development and progression of metabolic disease, immune dysfunction and affective disorders after SCI. As these new tools become more readily available and used across the research community, the development of an "ecogenomic" toolbox will facilitate an Eco-Systems Biology approach to study the complex interplay along the spinal cord-gut-immune axis after SCI.

Hepatic dysfunction after spinal cord injury: A vicious cycle of central and peripheral pathology?

The liver is essential for numerous physiological processes, including filtering blood from the intestines, metabolizing fats, proteins, carbohydrates and drugs, and regulating iron storage and release. The liver is also an important immune organ and plays a critical role in response to infection and injury throughout the body. Liver functions are regulated by autonomic parasympathetic innervation from the brainstem and sympathetic innervation from the thoracic spinal cord. Thus, spinal cord injury (SCI) at or above thoracic levels disrupts major regulatory mechanisms for hepatic functions. Work in rodents and humans shows that SCI induces liver pathology, including hepatic inflammation and fat accumulation characteristic of a serious form of non-alcoholic fatty liver disease (NAFLD) called non-alcoholic steatohepatitis (NASH). This hepatic pathology is associated with and likely contributes to indices of metabolic dysfunction often noted in SCI individuals, such as insulin resistance and hyperlipidemia. These occur at greater rates in the SCI population and can negatively impact health and quality of life. In this review, we will: 1) Discuss acute and chronic changes in human and rodent liver pathology and function after SCI; 2) Describe how these hepatic changes affect systemic inflammation, iron regulation and metabolic dysfunction after SCI; 3) Describe how disruption of the hepatic autonomic nervous system may be a key culprit in post-injury chronic liver pathology; and 4) Preview ongoing and future research that aims to elucidate mechanisms driving liver and metabolic dysfunction after SCI.

Low-Dose Testosterone and Evoked Resistance Exercise after Spinal Cord Injury on Cardio-Metabolic Risk Factors: An Open-Label Randomized Clinical Trial

The purpose of the work is to investigate the effects of low-dose testosterone replacement therapy (TRT) and evoked resistance training (RT) on body composition and metabolic variables after spinal cord injury (SCI). Twenty-two individuals with chronic motor complete SCI (ages 18-50 years) were randomly assigned to either TRT+RT (n = 11) or TRT (n = 11) for 16 weeks following a 4 -week delayed entry period. TRT+RT men underwent twice weekly progressive RT using electrical stimulation with ankle weights. TRT was administered via testosterone patches (2-6 mg/day). Body composition was tested using anthropometrics, dual energy x-ray absorptiometry, and magnetic resonance imaging. After an overnight fast, basal metabolic rate (BMR), lipid panel, serum testosterone, adiponectin, inflammatory and anabolic biomarkers (insulin-like growth factor-1 and insulin-like growth factor-binding protein 3 [IGFBP-3]), glucose effectiveness (Sg), and insulin sensitivity (Si) were measured. Total body lean mass (LM; 2.7 kg, p < 0.0001), whole muscle (p < 0.0001), and whole muscle knee extensor cross-sectional areas (CSAs; p < 0.0001) increased in the TRT+RT group, with no changes in the TRT group. Visceral adiposity decreased (p = 0.049) in the TRT group, with a trend in the TRT+RT (p = 0.07) group. There was a trend (p = 0.050) of a 14-17% increase in BMR following TRT+RT. Sg showed a trend (p = 0.07) to improvement by 28.5-31.5% following both interventions. IGFBP-3 increased (p = 0.0001) while IL-6 decreased (p = 0.039) following both interventions, and TRT+RT suppressed adiponectin (p = 0.024). TRT+RT resulted in an increase in LM and whole thigh and knee extensor muscle CSAs, with an increase in BMR and suppressed adiponectin. Low-dose TRT may mediate modest effects on visceral adipose tissue, Sg, IGFBP-3, and IL-6, independent of changes in LM.

Skeletal muscle hypertrophy and attenuation of cardio-metabolic risk factors (SHARC) using functional electrical stimulation-lower extremity cycling in persons with spinal cord injury: study protocol for a randomized clinical trial

Background

Persons with spinal cord injury (SCI) are at heightened risks of developing unfavorable cardiometabolic consequences due to physical inactivity. Functional electrical stimulation (FES) and surface neuromuscular electrical stimulation (NMES)-resistance training (RT) have emerged as effective rehabilitation methods that can exercise muscles below the level of injury and attenuate cardio-metabolic risk factors. Our aims are to determine the impact of 12 weeks of NMES + 12 weeks of FES-lower extremity cycling (LEC) compared to 12 weeks of passive movement + 12 weeks of FES-LEC on: (1) oxygen uptake (VO₂), insulin sensitivity, and glucose disposal in adults with SCI; (2) skeletal muscle size, intramuscular fat (IMF), and visceral adipose tissue (VAT); and (3) protein expression of energy metabolism, protein molecules involved in insulin signaling, muscle hypertrophy, and oxygen uptake and electron transport chain (ETC) activities.

Methods/Design

Forty-eight persons aged 18–65 years with chronic (> 1 year) SCI/D (AIS A-C) at the C5-L2 levels, equally sub-grouped by cervical or sub-cervical injury levels and time since injury, will be randomized into either the NMES + FES group or Passive + FES (control group). The NMES + FES group will undergo 12 weeks of evoked RT using twice-weekly NMES and ankle weights followed by twice-weekly progressive FES-LEC for an additional 12 weeks. The control group will undergo 12 weeks of passive movement followed by 12 weeks of progressive FES-LEC. Measurements will be performed at baseline (B; week 0), post-intervention 1 (P1; week 13), and post-intervention 2 (P2; week 25), and will include: VO₂ measurements, insulin sensitivity, and glucose effectiveness using intravenous glucose tolerance test; magnetic resonance imaging to measure muscle, IMF, and VAT areas; muscle biopsy to measure protein expression and intracellular signaling; and mitochondrial ETC function.

Discussion

Training through NMES + RT may evoke muscle hypertrophy and positively impact oxygen uptake, insulin sensitivity, and glucose effectiveness. This may result in beneficial outcomes on metabolic activity, body composition profile, mitochondrial ETC, and intracellular signaling related to insulin action and muscle hypertrophy. In the future, NMES-RT may be added to FES-LEC to improve the workloads achieved in the rehabilitation of persons with SCI and further decrease muscle wasting and cardio-metabolic risks.

Trial registration

ClinicalTrials.gov, NCT02660073. Registered on 21 Jan 2016.

Utilizing a low-carbohydrate/high-protein diet to improve metabolic health in individuals with spinal cord injury (DISH): study protocol for a randomized controlled trial

Background

Metabolic disorders (e.g., impaired glucose tolerance, insulin resistance, and type 2 diabetes) are more prevalent in people with spinal cord injury (SCI) than able-bodied individuals. Dietary modification is a more cost-effective treatment option than pharmacological therapies for reducing the risk of metabolic dysfunction. Lowering carbohydrate, increasing protein, and maintaining a proper dietary fat intake are expected to induce favorable adaptations in glucose control, body fat distribution, and the composition of the gut microbiome. However, dietary modification has not been rigorously investigated in people with SCI. The purpose of this study is to determine if an 8-week low-carbohydrate/high-protein (LC/HP) dietary intervention will show improvements in clinically important metrics of metabolic function, body composition, the composition of gut bacteria, and quality of life.

Methods/design

We intend to recruit 100 participants with chronic traumatic SCI (3 years postinjury, C5–L2, American Spinal Injury Association impairment scale A–D, and aged 18–65 years) and insulin resistance, impaired glucose tolerance or untreated type 2 diabetes and randomly assign them to an 8-week LC/HP dietary intervention group or a control group. The daily LC/HP dietary intervention includes ~ 30% total energy as protein (1.6 g/kg per day) with a carbohydrate-to-protein ratio < 1.5 and fat intake set at ~ 30% of the total energy intake. The control group does not receive any dietary intervention and are continuing with their regular daily diets. Glucose tolerance, insulin sensitivity, β-cell function, body composition, gut microbiome composition, and quality of life measures are assessed at week 1, before starting the LC/HP dietary intervention, and at week 8, after completion of the LC/HP dietary intervention.

Discussion

New information derived from this project will result in the development of a low-cost, simple, self-administered LC/HP dietary intervention for improving metabolic function in individuals with chronic SCI, improved understanding of the composition of gut bacteria in SCI, and how a LC/HP dietary intervention alters gut bacteria composition. In addition, this project will improve our understanding of the relationship between metabolic function and quality of life in individuals with long-standing SCI.

Trial registration

ClinicalTrials.gov, NCT03207841. Registered on 5 June 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3520-3) contains supplementary material, which is available to authorized users.

Differences in Glucose Metabolism Among Women With Spinal Cord Injury May Not Be Fully Explained by Variations in Body Composition

OBJECTIVE

To investigate the differences in glucose metabolism among women with paraplegic, and tetraplegic spinal cord injury (SCI) in comparison to their able-bodied (AB) counterparts after adjusting for differences in body composition.

DESIGN

Cross-sectional study. After an overnight fast, each participant consumed a 75-g glucose solution for oral glucose tolerance test (OGTT). Blood glucose, insulin, and C-peptide concentrations were analyzed before and 30, 60, 90, and 120 minutes after ingesting glucose solution. Insulin sensitivity index (ISI) was estimated using the Matsuda index. Percentage fat mass (%FM) and total body lean mass (TBLM) were estimated using data from dual-energy x-ray absorptiometry. Visceral fat (VF) was quantified using computed tomography. Outcome measures were compared among groups using analysis of covariance with %FM (or VF) and TBLM as covariates.

SETTING

Research university.

PARTICIPANTS

Women (N=42) with SCI (tetraplegia: n=8; paraplegia: n=14) and their race-, body mass index-, and age-matched AB counterparts (n=20).

INTERVENTIONS

Not applicable.

RESULTS

At fasting, there was no difference in glucose homeostasis (glucose, insulin, C-peptide concentrations) among 3 groups of women. In contrast, glucose, insulin, and C-peptide concentrations at minute 120 during OGTT were higher in women with tetraplegia versus women with paraplegia and AB women (P<.05, adjusted for TBLM and %FM). In addition, women with tetraplegia had lower ISI (P<.05, adjusted for TBLM and %FM) versus AB women. These differences remained after adjusting for VF and TBLM.

CONCLUSION

Our study confirms that impaired glucose metabolism among women with tetraplegia may not be fully explained by changes in their body composition. Future studies exploring additional factors involved in glucose metabolism are warranted.

Anthropometric cutoffs and associations with visceral adiposity and metabolic biomarkers after spinal cord injury

Background/Objectives

To examine associations of different anthropometric measurements of central adiposity to visceral adipose tissue (measured via multi-axial magnetic resonance imaging; MRI) and cardiometabolic disease risk factors in men with spinal cord injury (SCI). Additionally, to determine population-specific seated/supine waist and abdominal circumference cutoffs, which may identify men at increased risk of cardiometabolic disease.

Participants/Methods

Twenty-two men with chronic SCI underwent MRI scans, anthropometric measurements along with assessments of various cardiometabolic risk biomarkers. Pearson/part (accounting for age as a covariate) correlation coefficients were calculated to determine the associations between study variables. Abdominal and waist circumference cutoffs were extrapolated using the slope of linear regression equations.

Results

Seated/supine abdominal and waist circumferences were (P < 0.01) associated with MRI visceral fat cross-sectional area (VAT_CSA), VAT volume and CSA:Total_CSA. Low density lipoprotein, non-high-density lipoprotein and total cholesterol were positively associated with seated/supine abdominal and waist circumferences after controlling for age; r = 0.50–0.61, r = 0.46–0.58, r = 0.52–0.58, P < 0.05, respectively. Tumor necrosis factor alpha was associated with seated/supine abdominal and waist circumferences after accounting for age; r = 0.49–0.51 and r = 0.48–0.56, P < 0.05 respectively. The population-specific cutoffs were 86.5cm and 88.3cm for supine waist and abdominal circumferences, respectively, as well as 89cm and 101cm for seated waist and abdominal circumferences, respectively. After dichotomizing VAT_CSA (< or ≥ 100cm²), peak oxygen uptake, triglycerides, insulin sensitivity and glycated hemoglobin were different (P < 0.05) between groups. After dichotomizing (< or ≥ 86.5cm) supine waist circumference, VAT_CSA, triglycerides and insulin sensitivity were different (P < 0.05) between groups.

Conclusions

Seated/supine circumferences are associated with both central adiposity and biomarkers of cardiometabolic disease risk in persons with SCI. Population-specific cutoffs are proposed herein to identify central adiposity and potential cardiometabolic disease risk after SCI.

Plasma adiponectin levels are correlated with body composition, metabolic profiles, and mitochondrial markers in individuals with chronic spinal cord injury

STUDY DESIGN

Cross-sectional design.

OBJECTIVES

This study examined the relationships between circulating adiponectin levels, body composition, metabolic profile, and measures of skeletal muscle mitochondrial enzyme activity and biogenesis.

SETTINGS

Clinical Research in a Medical Center.

METHODS

Plasma adiponectin was quantified in 19 individuals with chronic spinal cord injury (SCI). Body composition was evaluated by dual x-ray absorptiometry and magnetic resonance imaging. Metabolic profile was assessed by basal metabolic rate (BMR), oxygen uptake (VO₂), and intravenous glucose tolerance testing. Mitochondrial enzyme activity of skeletal muscle was obtained by spectrophotometric assays and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and 5' AMP-activated protein kinase (AMPK) protein expression was assessed by Western blots.

RESULTS

Adiponectin was negatively related to both total and regional fat mass and positively related to lean mass and muscle mass. Furthermore, there were positive relationships between adiponectin and BMR (r = 0.52, P = 0.02) and VO₂ (r = 0.73, P = 0.01). Furthermore, adiponectin was positively related to citrate synthase (r = 0.68, P = 0.002) and complex III activity (r = 0.57, P = 0.02). The relationships between adiponectin and body composition remained significant after accounting for age. The relationships between adiponectin, metabolic profile, and markers of mitochondria mass and activity were influenced by age.

CONCLUSIONS

The study demonstrated that adiponectin is closely related to body composition and metabolic profile in persons with SCI and further supports mechanistic studies suggesting that adiponectin may stimulate mitochondrial biogenesis.