Exercise-induced overexpression of key regulatory proteins involved in glucose uptake and metabolism in tetraplegic persons: molecular mechanism for improved glucose homeostasis

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.

Extreme Variations in Muscle Fiber Composition Enable Detection of Insulin Resistance and Excessive Insulin Secretion

CONTEXT

Muscle fiber composition is associated with peripheral insulin action.

OBJECTIVE

We investigated whether extreme differences in muscle fiber composition are associated with alterations in peripheral insulin action and secretion in young, healthy subjects who exhibit normal fasting glycemia and insulinemia.

METHODS

Relaxation time following a tetanic contraction was used to identify subjects with a high or low expression of type I muscle fibers: group 1 (n = 11), area occupied by type I muscle fibers = 61.0 ± 11.8%, and group 2 (n = 8), type I area = 36.0 ± 4.9% (P < 0.001). Biopsies were obtained from the vastus lateralis muscle and analyzed for mitochondrial respiration on permeabilized fibers, muscle fiber composition, and capillary density. An intravenous glucose tolerance test was performed and indices of glucose tolerance, insulin sensitivity, and secretion were determined.

RESULTS

Glucose tolerance was similar between groups, whereas whole-body insulin sensitivity was decreased by ~50% in group 2 vs group 1 (P = 0.019). First-phase insulin release (area under the insulin curve during 10 minutes after glucose infusion) was increased by almost 4-fold in group 2 vs group 1 (P = 0.01). Whole-body insulin sensitivity was correlated with percentage area occupied by type I fibers (r = 0.54; P = 0.018) and capillary density in muscle (r = 0.61; P = 0.005) but not with mitochondrial respiration. Insulin release was strongly related to percentage area occupied by type II fibers (r = 0.93; P < 0.001).

CONCLUSIONS

Assessment of muscle contractile function in young healthy subjects may prove useful in identifying individuals with insulin resistance and enhanced glucose-stimulated insulin secretion prior to onset of clinical manifestations.

Enhancement of anaerobic glycolysis - a role of PGC-1α4 in resistance exercise

Resistance exercise training (RET) is an effective countermeasure to sarcopenia, related frailty and metabolic disorders. Here, we show that an RET-induced increase in PGC-1α4 (an isoform of the transcriptional co-activator PGC-1α) expression not only promotes muscle hypertrophy but also enhances glycolysis, providing a rapid supply of ATP for muscle contractions. In human skeletal muscle, PGC-1α4 binds to the nuclear receptor PPARβ following RET, resulting in downstream effects on the expressions of key glycolytic genes. In myotubes, we show that PGC-1α4 overexpression increases anaerobic glycolysis in a PPARβ-dependent manner and promotes muscle glucose uptake and fat oxidation. In contrast, we found that an acute resistance exercise bout activates glycolysis in an AMPK-dependent manner. These results provide a mechanistic link between RET and improved glucose metabolism, offering an important therapeutic target to counteract aging and inactivity-induced metabolic diseases benefitting those who cannot exercise due to many reasons.

Functional electrical stimulation cycling exercise after spinal cord injury: a systematic review of health and fitness-related outcomes

OBJECTIVES

The objective of this review was to summarize and appraise evidence on functional electrical stimulation (FES) cycling exercise after spinal cord injury (SCI), in order to inform the development of evidence-based clinical practice guidelines.

METHODS

PubMed, the Cochrane Central Register of Controlled Trials, EMBASE, SPORTDiscus, and CINAHL were searched up to April 2021 to identify FES cycling exercise intervention studies including adults with SCI. In order to capture the widest array of evidence available, any outcome measure employed in such studies was considered eligible. Two independent reviewers conducted study eligibility screening, data extraction, and quality appraisal using Cochranes' Risk of Bias or Downs and Black tools. Each study was designated as a Level 1, 2, 3 or 4 study, dependent on study design and quality appraisal scores. The certainty of the evidence for each outcome was assessed using GRADE ratings ('High', 'Moderate', 'Low', or 'Very low').

RESULTS

Ninety-two studies met the eligibility criteria, comprising 999 adults with SCI representing all age, sex, time since injury, lesion level and lesion completeness strata. For muscle health (e.g., muscle mass, fiber type composition), significant improvements were found in 3 out of 4 Level 1-2 studies, and 27 out of 32 Level 3-4 studies (GRADE rating: 'High'). Although lacking Level 1-2 studies, significant improvements were also found in nearly all of 35 Level 3-4 studies on power output and aerobic fitness (e.g., peak power and oxygen uptake during an FES cycling test) (GRADE ratings: 'Low').

CONCLUSION

Current evidence indicates that FES cycling exercise improves lower-body muscle health of adults with SCI, and may increase power output and aerobic fitness. The evidence summarized and appraised in this review can inform the development of the first international, evidence-based clinical practice guidelines for the use of FES cycling exercise in clinical and community settings of adults with SCI. Registration review protocol: CRD42018108940 (PROSPERO).

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.

Sixteen weeks of testosterone with or without evoked resistance training on protein expression, fiber hypertrophy and mitochondrial health after spinal cord injury

We investigated the effects of testosterone replacement therapy (TRT) with and without evoked resistance training (RT) on protein expression of key metabolic and hypertrophy regulators, muscle fiber cross-sectional area (CSA), and markers of mitochondrial health after spinal cord injury (SCI). Twenty-two men with chronic motor complete SCI were randomly assigned to either TRT + RT (n = 11) or TRT (n = 11) for 16 wk. TRT + RT men underwent twice weekly progressive RT using electrical stimulation with ankle weights. TRT was administered via testosterone patches (2-6 mg/day). Muscle biopsies were obtained before and after 16 wk from the right vastus lateralis. Expression of proteins associated with oxidative muscles and mechanical loading (PGC-1α and FAK), muscle hypertrophy (total and phosphorylated Akt, total and phosphorylated mTOR), and cellular metabolism (total and phosphorylated AMPK and GLUT4) were evaluated. Immunohistochemistry analysis was performed to measure fiber CSA and succinate dehydrogenase (SDH) activity as well as mitochondrial citrate synthase (CS) activity and complex III (CIII) activities. TRT + RT demonstrated a robust 27.5% increase in average fiber CSA compared with a -9% decrease following TRT only (P = 0.01). GLUT4 protein expression was elevated in the TRT + RT group compared with TRT only (P = 0.005). Total Akt (P = 0.06) and phosphorylated Akt Ser³⁸⁹ (P = 0.049) were also elevated in the TRT + RT group. Mitochondrial activity of SDH (P = 0.03) and CS (P = 0.006) increased in the TRT + RT group, with no changes in the TRT-only group. Sixteen weeks of TRT with RT resulted in fiber hypertrophy and beneficial changes in markers of skeletal muscle health and function.NEW & NOTEWORTHY Fiber cross-sectional area (CSA), protein expression, mitochondrial citrate synthase (CS), and succinate dehydrogenase (SDH) were measured following 16 wk of low-dose testosterone replacement therapy (TRT) with and without electrically evoked resistance training (RT) in men with spinal cord injury (SCI). Fiber CSA and protein expression of total GLUT4, total Akt, and phosphorylated Akt increased following TRT + RT but not in the TRT-only group. Mitochondrial CS and SDH increased after TRT + RT but not in TRT-only group.

Retained differentiation capacity of human skeletal muscle satellite cells from spinal cord-injured individuals

Despite the well‐known role of satellite cells in skeletal muscle plasticity, the effect of spinal cord injury on their function in humans remains unknown. We determined whether spinal cord injury affects the intrinsic ability of satellite cells to differentiate and produce metabolically healthy myotubes. We obtained vastus lateralis biopsies from eight spinal cord‐injured and six able‐bodied individuals. Satellite cells were isolated, grown and differentiated in vitro. Gene expression was measured by quantitative PCR. Abundance of differentiation markers and regulatory proteins was determined by Western blotting. Protein synthesis and fatty acid oxidation were measured by radioactive tracer‐based assays. Activated satellite cells (myoblasts) and differentiated myotubes derived from skeletal muscle of able‐bodied and spinal cord‐injured individuals expressed similar (P > 0.05) mRNA levels of myogenic regulatory factors. Myogenic differentiation factor 1 expression was higher in myoblasts from spinal cord‐injured individuals. Desmin and myogenin protein content was increased upon differentiation in both groups, while myotubes from spinal cord‐injured individuals contained more type I and II myosin heavy chain. Phosphorylated and total protein levels of Akt‐mechanistic target of rapamycin and forkhead box protein O signalling axes and protein synthesis rate in myotubes were similar (P > 0.05) between groups. Additionally, fatty acid oxidation of myotubes from spinal cord‐injured individuals was unchanged (P > 0.05) compared to able‐bodied controls. Our results indicate that the intrinsic differentiation capacity of satellite cells and metabolic characteristics of myotubes are preserved following spinal cord injury. This may inform potential interventions targeting satellite cell activation to alleviate skeletal muscle atrophy.

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.

Protein translation, proteolysis and autophagy in human skeletal muscle atrophy after spinal cord injury

AIM

Spinal cord injury-induced loss of skeletal muscle mass does not progress linearly. In humans, peak muscle loss occurs during the first 6 weeks postinjury, and gradually continues thereafter. The aim of this study was to delineate the regulatory events underlying skeletal muscle atrophy during the first year following spinal cord injury.

METHODS

Key translational, autophagic and proteolytic proteins were analysed by immunoblotting of human vastus lateralis muscle obtained 1, 3 and 12 months following spinal cord injury. Age-matched able-bodied control subjects were also studied.

RESULTS

Several downstream targets of Akt signalling decreased after spinal cord injury in skeletal muscle, without changes in resting Akt Ser⁴⁷³ and Akt Thr³⁰⁸ phosphorylation or total Akt protein. Abundance of mTOR protein and mTOR Ser²⁴⁴⁸ phosphorylation, as well as FOXO1 Ser²⁵⁶ phosphorylation and FOXO3 protein, decreased in response to spinal cord injury, coincident with attenuated protein abundance of E3 ubiquitin ligases, MuRF1 and MAFbx. S6 protein and Ser^235/236 phosphorylation, as well as 4E-BP1 Thr^37/46 phosphorylation, increased transiently after spinal cord injury, indicating higher levels of protein translation early after injury. Protein abundance of LC3-I and LC3-II decreased 3 months postinjury as compared with 1 month postinjury, but not compared to able-bodied control subjects, indicating lower levels of autophagy. Proteins regulating proteasomal degradation were stably increased in response to spinal cord injury.

CONCLUSION

Together, these data provide indirect evidence suggesting that protein translation and autophagy transiently increase, while whole proteolysis remains stably higher in skeletal muscle within the first year after spinal cord injury.

Impact of Exercise on Cardiometabolic Component Risks in Spinal Cord-injured Humans

Purpose

Spinal cord injury (SCI) creates a complex pathology, characterized by low levels of habitual physical activity and an increased risk of cardiometabolic disease. This study aimed to assess the effect of a moderate-intensity upper-body exercise training intervention on biomarkers of cardiometabolic component risks, adipose tissue metabolism, and cardiorespiratory fitness in persons with SCI.

Methods

Twenty-one inactive men and women with chronic (>1 yr) SCI (all paraplegic injuries) 47 ± 8 yr of age (mean ± SD) were randomly allocated to either a 6-wk prescribed home-based exercise intervention (INT; n = 13) or control group (CON; n = 8). Participants assigned to the exercise group completed 4 × 45-min moderate-intensity (60%–65% peak oxygen uptake (V˙O_2peak)) arm-crank exercise sessions per week. At baseline and follow-up, fasted and postload blood samples (collected during oral glucose tolerance tests) were obtained to measure metabolic regulation and biomarkers of cardiovascular disease. Abdominal subcutaneous adipose tissue biopsies were also obtained, and cardiorespiratory fitness was assessed.

Results

Compared with CON, INT significantly decreased (P = 0.04) serum fasting insulin (Δ, 3.1 ± 10.7 pmol·L⁻¹ for CON and −12.7 ± 18.7 pmol·L⁻¹ for INT) and homeostasis model assessment of insulin resistance (HOMA2-IR; Δ, 0.06 ± 0.20 for CON and −0.23 ± 0.36 for INT). The exercise group also increased V˙O_2peak (Δ, 3.4 mL·kg⁻¹·min⁻¹; P ≤ 0.001). Adipose tissue metabolism, composite insulin sensitivity index (C-ISI_Matsuda), and other cardiovascular disease risk biomarkers were not different between groups.

Conclusions

Moderate-intensity upper-body exercise improved aspects of metabolic regulation and cardiorespiratory fitness. Changes in fasting insulin and HOMA2-IR, but not C-ISI_Matsuda, suggest improved hepatic but not peripheral insulin sensitivity after 6 wk of exercise training in persons with chronic paraplegia.

Exercise for pregnant women with pre-existing diabetes for improving maternal and fetal outcomes

BACKGROUND

Pregnancies with pre-existing diabetes are high risk, with increased risk of poorer fetal, neonatal, and maternal outcomes. Identifying interventions to improving health outcomes for women with diabetes and their infants is a priority, as rates of diabetes continue to increase.Exercise has been shown to have benefits for non-pregnant individuals with pre-existing type 2 diabetes, such as improving glycaemic control, and reducing visceral adipose tissue and plasma triglycerides. For pregnant women with pre-existing diabetes, the effects of exercise interventions on the mother and her baby are unknown.An earlier Cochrane review on 'Exercise for pregnant women with diabetes' considered both pre-existing diabetes and gestational diabetes. That Cochrane review has now been split into two new reviews (following new protocols) - one on gestational diabetes and one on pre-existing diabetes (this review).

OBJECTIVES

To evaluate the effects of exercise interventions for improving maternal and fetal outcomes in women with pre-existing diabetes.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform (ICTRP) on 27 June 2017, and reference lists of retrieved studies.

SELECTION CRITERIA

We had planned to include published or unpublished randomised controlled trials (RCT) or cluster-randomised trials, in full text or abstract format that compared any type of exercise programme, added to standard care, targeted at women with known pre-gestational diabetes (type 1 or type 2 diabetes), at any stage of pregnancy, compared with 1) standard care alone or 2) standard care plus another exercise intervention. Quasi-randomised and cross-over trials were excluded. Conference abstracts were handled in the same way as full-text publications.Women with gestational diabetes mellitus were excluded, as they were covered in a separate Cochrane review.

DATA COLLECTION AND ANALYSIS

We had planned that two review authors would independently assess all the potential studies we identified as a result of the search strategy. For eligible studies, two review authors would have independently extracted the data using an agreed form. We had planned to resolve discrepancies through discussion, or by consulting a third person. We also had planned to assess the evidence using the GRADE approach.

MAIN RESULTS

We did not identify any randomised controlled trials.

AUTHORS' CONCLUSIONS

There was no evidence from RCTs that evaluated the effects of exercise interventions for improving maternal and fetal outcomes in women with pre-existing diabetes.Good quality, large randomised controlled trials are urgently needed to identify exercise interventions that are safe, and improve health outcomes for women with pre-existing diabetes and their babies. Future studies in this area could utilise the standardised outcomes in this review, in order to improve consistency between trials in this area, and aid future meta-analysis.

Independent sailing with high tetraplegia using sip and puff controls: integration into a community sailing center

BACKGROUND

We are continually rediscovering how adapted recreational activity complements the rehabilitation process, enriches patients' lives and positively impacts outcome measures. Although sports for people with spinal cord injuries (SCI) has achieved spectacular visibility, participation by high cervical injuries is often restricted due to poor accessibility, safety concerns, lack of adaptability, and high costs of technology.

METHODS

We endeavor to demonstrate the mechanisms, adaptability, accessibility, and benefits the sport of sailing creates in the rehabilitative process. Our sailor is a 27-year-old man with a history of traumatic SCI resulting in C4 complete tetraplegia.

RESULTS

The participant completed an adapted introductory sailing course, and instruction on the sip-and-puff sail and tiller control mechanism. With practice, he navigated an on-water course in moderate winds of 5 to 15 knots.

DISCUSSION

Despite trends toward shorter rehabilitation stays, aggressive transdisciplinary collaboration with recreation therapy can provide community and natural environment experiences while inpatient and continuing post discharge. Such peak physical and psychological experiences provide a positive perspective for the future that can be shared on the inpatient unit, with families and support systems like sailing clubs in the community.

CONCLUSION

Rehabilitation theory directs a team process to achieve patient self-awareness and initiate self-actualization in spite of disablement. Utilization of local community sailing centers that have provided accessible assisted options provides person-centered self-realization of goals as assisted by family and natural supports. Such successful patients become native guides for others seeking the same experience.

Abundance in proteins expressed after functional electrical stimulation cycling or arm cycling ergometry training in persons with chronic spinal cord injury

STUDY DESIGN

Longitudinal design.

OBJECTIVES

The study determined the effects of two forms of exercise training on the abundance of two proteins, (glucose transporter-4 [GLUT-4], adenosine monophosphate kinase [AMPK]) involved in glucose utilization and the transcriptional coactivator that regulates the genes involved in energy metabolism and mitochondrial biogenesis (peroxisome proliferator-activated receptor (PPAR) coactivator 1 alpha [PGC-1α]), in muscles in men with chronic motor-complete spinal cord injury (SCI).

SETTINGS

Clinical trial at a Medical Center.

METHODS

Nine men with chronic motor-complete SCI participated in functional electrical stimulation lower extremity cycling (FES-LEC; n = 4) or arm cycling ergometer (arm-cycling ergometer [ACE]; n = 5) 5 days/week for 16 weeks. Whole body composition was measured by dual energy X-ray absorptiometry. An intravenous glucose tolerance test was performed to measure glucose effectiveness (Sg) and insulin sensitivity (Si). Muscle biopsies of the right vastus lateralis (VL) and triceps muscles were collected one week prior to and post the exercise training intervention.

RESULTS

Neither training intervention altered body composition or carbohydrate metabolism. GLUT-4 increased by 3.8 fold in the VL after FES training and increased 0.6 fold in the triceps after ACE training. PGC-1α increased by 2.3 fold in the VL after FES training and 3.8 fold in the triceps after ACE training. AMPK increased by 3.4 fold in the VL after FES training and in the triceps after ACE training.

CONCLUSION

FES-LEC and ACE training were associated with greater protein expressions in the trained muscles by effectively influencing the abundance of GLUT-4, AMPK and PGC-1α. Thus, FES-LEC training of paralyzed muscle can modulate protein expression similar to that of trained and innervated muscle.

Exercise for pregnant women with gestational diabetes for improving maternal and fetal outcomes

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with both short- and long-term complications for the mother and her baby. Exercise interventions may be useful in helping with glycaemic control and improve maternal and infant outcomes.The original review on Exercise for diabetic pregnant women has been split into two new review titles reflecting the role of exercise for pregnant women with gestational diabetes and for pregnant women with pre-existing diabetes. Exercise for pregnant women with gestational diabetes for improving maternal and fetal outcomes (this review) Exercise for pregnant women with pre-existing diabetes for improving maternal and fetal outcomes OBJECTIVES: To evaluate the effects of exercise interventions for improving maternal and fetal outcomes in women with GDM.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (27 August 2016), ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (18th August 2016), and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing an exercise intervention with standard care or another intervention in pregnant women diagnosed with gestational diabetes. Quasi-randomised and cross-over studies, and studies including women with pre-existing type 1 or type 2 diabetes were not eligible for inclusion.

DATA COLLECTION AND ANALYSIS

All selection of studies, assessment of trial quality and data extraction was conducted independently by two review authors. Data were checked for accuracy.

MAIN RESULTS

We included 11 randomised trials, involving 638 women. The overall risk of bias was judged to be unclear due to lack of methodological detail in the included studies.For the mother, there was no clear evidence of a difference between women in the exercise group and those in the control group for the risk of pre-eclampsia as the measure of hypertensive disorders of pregnancy (risk ratio (RR) 0.31, 95% confidence interval (CI) 0.01 to 7.09; two RCTs, 48 women; low-quality evidence), birth by caesarean section (RR 0.86, 95% CI 0.63 to 1.16; five RCTs, 316 women; I2 = 0%; moderate-quality evidence), the risk of induction of labour (RR 1.38, 95% CI 0.71 to 2.68; one RCT, 40 women; low-quality evidence) or maternal body mass index at follow-up (postnatal weight retention or return to pre-pregnancy weight) (mean difference (MD) 0.11 kg/m2, 95% CI -1.04 to 1.26; three RCTs, 254 women; I2 = 0%; high-quality evidence). Development of type 2 diabetes, perineal trauma/tearing and postnatal depression were not reported as outcomes in the included studies.For the infant/child/adult, a single small (n = 19) trial reported no perinatal mortality (stillbirth and neonatal mortality) events in either the exercise intervention or control group (low-quality evidence). There was no clear evidence of a difference between groups for a mortality and morbidity composite (variously defined by trials, e.g. perinatal or infant death, shoulder dystocia, bone fracture or nerve palsy) (RR 0.56, 95% CI 0.12 to 2.61; two RCTs, 169 infants; I2 = 0%; moderate-quality evidence) or neonatal hypoglycaemia (RR 2.00, 95% CI 0.20 to 20.04; one RCT, 34 infants; low-quality evidence). None of the included trials pre-specified large-for-gestational age, adiposity (neonatal/infant, childhood or adulthood), diabetes (childhood or adulthood) or neurosensory disability (neonatal/infant) as trial outcomes.Other maternal outcomes of interest: exercise interventions were associated with both reduced fasting blood glucose concentrations (average standardised mean difference (SMD) -0.59, 95% CI -1.07 to -0.11; four RCTs, 363 women; I2 = 73%; T2 = 0.19) and a reduced postprandial blood glucose concentration compared with control interventions (average SMD -0.85, 95% CI -1.15 to -0.55; three RCTs, 344 women; I2 = 34%; T2 = 0.03).

AUTHORS' CONCLUSIONS

Short- and long-term outcomes of interest for this review were poorly reported. Current evidence is confounded by the large variety of exercise interventions. There was insufficient high-quality evidence to be able to determine any differences between exercise and control groups for our outcomes of interest. For the woman, both fasting and postprandial blood glucose concentrations were reduced compared with the control groups. There are currently insufficient data for us to determine if there are also benefits for the infant. The quality of the evidence in this review ranged from high to low quality and the main reason for downgrading was for risk of bias and imprecision (wide CIs, low event rates and small sample size). Development of type 2 diabetes, perineal trauma/tearing, postnatal depression, large-for-gestational age, adiposity (neonate/infant, childhood or adulthood), diabetes (childhood or adulthood) or neurosensory disability (neonate/infant) were not reported as outcomes in the included studies.Further research is required comparing different types of exercise interventions with control groups or with another exercise intervention that reports on both the short- and long-term outcomes (for both the mother and infant/child) as listed in this review.

Lifestyle interventions for the treatment of women with gestational diabetes

BACKGROUND

Gestational diabetes (GDM) is glucose intolerance, first recognised in pregnancy and usually resolving after birth. GDM is associated with both short- and long-term adverse effects for the mother and her infant. Lifestyle interventions are the primary therapeutic strategy for many women with GDM.

OBJECTIVES

To evaluate the effects of combined lifestyle interventions with or without pharmacotherapy in treating women with gestational diabetes.

SEARCH METHODS

We searched the Pregnancy and Childbirth Group's Trials Register (14 May 2016), ClinicalTrials.gov, WHO International Clinical Trials Registry Platform (ICTRP) (14th May 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

We included only randomised controlled trials comparing a lifestyle intervention with usual care or another intervention for the treatment of pregnant women with GDM. Quasi-randomised trials were excluded. Cross-over trials were not eligible for inclusion. Women with pre-existing type 1 or type 2 diabetes were excluded.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by the Cochrane Collaboration. All selection of studies, data extraction was conducted independently by two review authors.

MAIN RESULTS

Fifteen trials (in 45 reports) are included in this review (4501 women, 3768 infants). None of the trials were funded by a conditional grant from a pharmaceutical company. The lifestyle interventions included a wide variety of components such as education, diet, exercise and self-monitoring of blood glucose. The control group included usual antenatal care or diet alone. Using GRADE methodology, the quality of the evidence ranged from high to very low quality. The main reasons for downgrading evidence were inconsistency and risk of bias. We summarised the following data from the important outcomes of this review. Lifestyle intervention versus control groupFor the mother:There was no clear evidence of a difference between lifestyle intervention and control groups for the risk of hypertensive disorders of pregnancy (pre-eclampsia) (average risk ratio (RR) 0.70; 95% confidence interval (CI) 0.40 to 1.22; four trials, 2796 women; I2 = 79%, Tau2 = 0.23; low-quality evidence); caesarean section (average RR 0.90; 95% CI 0.78 to 1.05; 10 trials, 3545 women; I2 = 48%, Tau2 = 0.02; low-quality evidence); development of type 2 diabetes (up to a maximum of 10 years follow-up) (RR 0.98, 95% CI 0.54 to 1.76; two trials, 486 women; I2 = 16%; low-quality evidence); perineal trauma/tearing (RR 1.04, 95% CI 0.93 to 1.18; one trial, n = 1000 women; moderate-quality evidence) or induction of labour (average RR 1.20, 95% CI 0.99 to 1.46; four trials, n = 2699 women; I2 = 37%; high-quality evidence).More women in the lifestyle intervention group had met postpartum weight goals one year after birth than in the control group (RR 1.75, 95% CI 1.05 to 2.90; 156 women; one trial, low-quality evidence). Lifestyle interventions were associated with a decrease in the risk of postnatal depression compared with the control group (RR 0.49, 95% CI 0.31 to 0.78; one trial, n = 573 women; low-quality evidence).For the infant/child/adult:Lifestyle interventions were associated with a reduction in the risk of being born large-for-gestational age (LGA) (RR 0.60, 95% CI 0.50 to 0.71; six trials, 2994 infants; I2 = 4%; moderate-quality evidence). Birthweight and the incidence of macrosomia were lower in the lifestyle intervention group.Exposure to the lifestyle intervention was associated with decreased neonatal fat mass compared with the control group (mean difference (MD) -37.30 g, 95% CI -63.97 to -10.63; one trial, 958 infants; low-quality evidence). In childhood, there was no clear evidence of a difference between groups for body mass index (BMI) ≥ 85th percentile (RR 0.91, 95% CI 0.75 to 1.11; three trials, 767 children; I2 = 4%; moderate-quality evidence).There was no clear evidence of a difference between lifestyle intervention and control groups for the risk of perinatal death (RR 0.09, 95% CI 0.01 to 1.70; two trials, 1988 infants; low-quality evidence). Of 1988 infants, only five events were reported in total in the control group and there were no events in the lifestyle group. There was no clear evidence of a difference between lifestyle intervention and control groups for a composite of serious infant outcome/s (average RR 0.57, 95% CI 0.21 to 1.55; two trials, 1930 infants; I2 = 82%, Tau2 = 0.44; very low-quality evidence) or neonatal hypoglycaemia (average RR 0.99, 95% CI 0.65 to 1.52; six trials, 3000 infants; I2 = 48%, Tau2 = 0.12; moderate-quality evidence). Diabetes and adiposity in adulthood and neurosensory disability in later childhoodwere not prespecified or reported as outcomes for any of the trials included in this review.

AUTHORS' CONCLUSIONS

Lifestyle interventions are the primary therapeutic strategy for women with GDM. Women receiving lifestyle interventions were less likely to have postnatal depression and were more likely to achieve postpartum weight goals. Exposure to lifestyle interventions was associated with a decreased risk of the baby being born LGA and decreased neonatal adiposity. Long-term maternal and childhood/adulthood outcomes were poorly reported.The value of lifestyle interventions in low-and middle-income countries or for different ethnicities remains unclear. The longer-term benefits or harms of lifestyle interventions remains unclear due to limited reporting.The contribution of individual components of lifestyle interventions could not be assessed. Ten per cent of participants also received some form of pharmacological therapy. Lifestyle interventions are useful as the primary therapeutic strategy and most commonly include healthy eating, physical activity and self-monitoring of blood glucose concentrations.Future research could focus on which specific interventions are most useful (as the sole intervention without pharmacological treatment), which health professionals should give them and the optimal format for providing the information. Evaluation of long-term outcomes for the mother and her child should be a priority when planning future trials. There has been no in-depth exploration of the costs 'saved' from reduction in risk of LGA/macrosomia and potential longer-term risks for the infants.

Effects of Testosterone and Evoked Resistance Exercise after Spinal Cord Injury (TEREX-SCI): study protocol for a randomised controlled trial

INTRODUCTION

Individuals with spinal cord injury (SCI) are at a lifelong risk of obesity and chronic metabolic disorders including insulin resistance and dyslipidemia. Within a few weeks of injury, there is a significant decline in whole body fat-free mass, particularly lower extremity skeletal muscle mass, and subsequent increase in fat mass (FM). This is accompanied by a decrease in anabolic hormones including testosterone. Testosterone replacement therapy (TRT) has been shown to increase skeletal muscle mass and improve metabolic profile. Additionally, resistance training (RT) has been shown to increase lean mass and reduce metabolic disturbances in SCI and other clinical populations.

METHODS AND ANALYSIS

26 individuals with chronic, motor complete SCI between 18 and 50 years old were randomly assigned to a RT+TRT group (n=13) or a TRT group (n=13). 22 participants completed the initial 16-week training phase of the study and 4 participants withdrew. 12 participants of the 22 completed 16 weeks of detraining. The TRT was provided via transdermal testosterone patches (4-6 mg/day). The RT+TRT group had 16 weeks of supervised unilateral progressive RT using surface neuromuscular electrical stimulation with ankle weights. This study will investigate the effects of evoked RT+TRT or TRT alone on body composition (muscle cross-sectional area, visceral adipose tissue, %FM) and metabolic profile (glucose and lipid metabolism) in individuals with motor complete SCI. Findings from this study may help in designing exercise therapies to alleviate the deterioration in body composition after SCI and decrease the incidence of metabolic disorders in this clinical population.

ETHICS AND DISSEMINATION

The study is currently approved by the McGuire VA Medical Center and Virginia Commonwealth University. All participants read and signed approved consent forms. Results will be submitted to peer-reviewed journals and presented at national and international conferences.

TRIAL REGISTRATION NUMBER

Pre-result, NCT01652040.

MicroRNA-208b progressively declines after spinal cord injury in humans and is inversely related to myostatin expression

The effects of long-term physical inactivity on the expression of microRNAs involved in the regulation of skeletal muscle mass in humans are largely unknown. MicroRNAs are short, noncoding RNAs that fine-tune target expression through mRNA degradation or by inhibiting protein translation. Intronic to the slow, type I, muscle fiber type genes MYH7 and MYH7b, microRNA-208b and microRNA-499-5p are thought to fine-tune the expression of genes important for muscle growth, such as myostatin. Spinal cord injured humans are characterized by both skeletal muscle atrophy and transformation toward fast-twitch, type II fibers. We determined the expression of microRNA-208b, microRNA-499-5p, and myostatin in human skeletal muscle after complete cervical spinal cord injury. We also determined whether these microRNAs altered myostatin expression in rodent skeletal muscle. A progressive decline in skeletal muscle microRNA-208b and microRNA-499-5p expression occurred in humans during the first year after spinal cord injury and with long-standing spinal cord injury. Expression of myostatin was inversely correlated with microRNA-208b and microRNA-499-5p in human skeletal muscle after spinal cord injury. Overexpression of microRNA-208b in intact mouse skeletal muscle decreased myostatin expression, whereas microRNA-499-5p was without effect. In conclusion, we provide evidence for an inverse relationship between expression of microRNA-208b and its previously validated target myostatin in humans with severe skeletal muscle atrophy. Moreover, we provide direct evidence that microRNA-208b overexpression decreases myostatin gene expression in intact rodent muscle. Our results implicate that microRNA-208b modulates myostatin expression and this may play a role in the regulation of skeletal muscle mass following spinal cord injury.

The effects of electrical stimulation on body composition and metabolic profile after spinal cord injury--Part II

Diet and exercise are cornerstones in the management of obesity and associated metabolic complications, including insulin resistance, type 2 diabetes, and disturbances in the lipid profile. However, the role of exercise in managing body composition adaptations and metabolic disorders after spinal cord injury (SCI) is not well established. The current review summarizes evidence about the efficacy of using neuromuscular electrical stimulation or functional electrical stimulation in exercising the paralytic lower extremities to improve body composition and metabolic profile after SCI. There are a number of trials that investigated the effects on muscle cross-sectional area, fat-free mass, and glucose/lipid metabolism. The duration of the intervention in these trials varied from 6 weeks to 24 months. Training frequency ranged from 2 to 5 days/week. Most studies documented significant increases in muscle size but no noticeable changes in adipose tissue. While increases in skeletal muscle size after twice weekly training were greater than those trials that used 3 or 5 days/week, other factors such as differences in the training mode, i.e. resistance versus cycling exercise and pattern of muscle activation may be responsible for this observation. Loading to evoke muscle hypertrophy is a key component in neuromuscular training after SCI. The overall effects on lean mass were modest and did not exceed 10% and the effects of training on trunk or pelvic muscles remain unestablished. Most studies reported improvement in glucose metabolism with the enhancement of insulin sensitivity being the major factor following training. The effect on lipid profile is unclear and warrants further investigation.

Physical exercise is associated with better fat mass distribution and lower insulin resistance in spinal cord injured individuals

OBJECTIVES

The aim of the study was to compare total and regional body composition and their relationship with glucose homeostasis in physically active and non-active individuals with cervical spinal cord injury (c-SCI).

METHODS

Individuals with lesion level between C5-C7 were divided into two groups: physically active (PA; n = 14; who practiced physical exercise for at least 3 months, three times per week or more, minimum of 150 minutes/week): and non-physically active (N-PA n = 8). Total fat mass (t-FM) and regional fat mass (r-FM) were assessed by dual energy X-ray absorptiometry. Fasting plasma insulin (FPI) was determined by enzyme-linked immunosorbent assay.

RESULTS

PA group present lower (P < 0.01) total fat mass (t-FM), % and kg, regional fat mass (r-FM), % and kg, FPI levels and HOMA index, while they had higher (P < 0.001) total free fat mass (t-FFM), %, and regional free fat mass (r-FFM), %, compared to the N-PA group. In the N-PA group, FPI and HOMA index were negatively (P < 0.05) correlated with FFM% (r = -0.71, -0.69, respectively) and positively correlated to trunk-FM (r = 0.71, 0.69, respectively) and trunk-FM:t-FM (kg) ratio (r = 0.83, 0.79, respectively).

CONCLUSION

Physical exercise is associated with lower t-FM, r-FM, and insulin resistance, which could contribute to the decrease of the risk of cardiovascular and metabolic conditions in individuals with c-SCI.

Altered content of AMP-activated protein kinase isoforms in skeletal muscle from spinal cord injured subjects

AMP-activated protein kinase (AMPK) is a pivotal regulator of energy homeostasis. Although downstream targets of AMPK are widely characterized, the physiological factors governing isoform expression of this protein kinase are largely unknown. Nerve/contractile activity has a major impact on the metabolic phenotype of skeletal muscle, therefore likely to influence AMPK isoform expression. Spinal cord injury represents an extreme form of physical inactivity, with concomitant changes in skeletal muscle metabolism. We assessed the influence of longstanding and recent spinal cord injury on protein abundance of AMPK isoforms in human skeletal muscle. We also determined muscle fiber type as a marker of glycolytic or oxidative metabolism. In subjects with longstanding complete injury, protein abundance of the AMPKγ3 subunit, as well as myosin heavy chain (MHC) IIa and IIx, were increased, whereas abundance of the AMPKγ1 subunit and MHC I were decreased. Similarly, abundance of AMPKγ3 and MHC IIa proteins were increased, whereas AMPKα2, -β1, and -γ1 subunits and MHC I abundance was decreased during the first year following injury, reflecting a more glycolytic phenotype of the skeletal muscle. However, in incomplete cervical lesions, partial recovery of muscle function attenuated the changes in the isoform profile of AMPK and MHC. Furthermore, exercise training (electrically stimulated leg cycling) partly normalized mRNA expression of AMPK isoforms. Thus, physical activity affects the relative expression of AMPK isoforms. In conclusion, skeletal muscle abundance of AMPK isoforms is related to physical activity and/or muscle fiber type. Thus, physical/neuromuscular activity is an important determinant of isoform abundance of AMPK and MCH. This further underscores the need for physical activity as part of a treatment regimen after spinal cord injury to maintain skeletal muscle metabolism.

Effect of training intensity on physical capacity, lipid profile and insulin sensitivity in early rehabilitation of spinal cord injured individuals

STUDY DESIGN

Pre-post training intervention.

OBJECTIVES

To evaluate the effect of training intensity on physical capacity, lipid profile and insulin sensitivity in early rehabilitation of spinal cord injured (SCI) patients, and to assess the correlation between peak aerobic capacity (VO(2Peak)) and insulin sensitivity.

SETTING

Spinal Cord Rehabilitation Unit, Sunnaas Hospital, Nesoddtangen, Norway.

METHOD

Six recently injured SCI individuals participated in the arm training intervention and were randomly admitted to a high-intensity (HI; 70-80% heart rate reserve (HRR)) and low-intensity (LI; 40-50% HRR) group. The 1 h interval training consisted of 3 min exercise bouts interspersed with 2 min of rest, three times a week for 8 weeks. In addition, a correlation coefficient was obtained between VO(2Peak) and insulin sensitivity in 11 SCI patients.

RESULTS

The 8-week training program resulted in a significant increase in VO(2Peak) and maximal power output (PO(Max)) for the group as a whole (P<0.05). VO(2Peak) increased significantly more and total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C) ratio and triglycerids decreased significantly more in the HI group than in the LI group (P=0.05). Training-induced changes in insulin sensitivity were significantly different between the groups (P=0.05), which was due to a nonsignificant decline in insulin sensitivity in the HI group and a nonsignificant improvement in the LI group. A significant positive correlation was found between VO(2peak) and insulin sensitivity (r=0.68, P=0.02).

CONCLUSION

The interval arm training protocol as used in the present study enables recently injured SCI patients to do substantial work at a relatively high intensity. Results indicate that improvements in physical capacity and lipid profile were more pronounced in response to high-intensity training. The significant correlation between maximal oxygen consumption and insulin sensitivity indicates that, as in the able-bodied population, peak aerobic capacity is a predictive value with regard to insulin sensitivity in SCI. Future studies with larger groups assessing the role of exercise intensity on insulin sensitivity in SCI are suggested.

Influence of chronic and acute spinal cord injury on skeletal muscle Na+-K+-ATPase and phospholemman expression in humans

Na(+)-K(+)-ATPase is an integral membrane protein crucial for the maintenance of ion homeostasis and skeletal muscle contractibility. Skeletal muscle Na(+)-K(+)-ATPase content displays remarkable plasticity in response to long-term increase in physiological demand, such as exercise training. However, the adaptations in Na(+)-K(+)-ATPase function in response to a suddenly decreased and/or habitually low level of physical activity, especially after a spinal cord injury (SCI), are incompletely known. We tested the hypothesis that skeletal muscle content of Na(+)-K(+)-ATPase and the associated regulatory proteins from the FXYD family is altered in SCI patients in a manner dependent on the severity of the spinal cord lesion and postinjury level of physical activity. Three different groups were studied: 1) six subjects with chronic complete cervical SCI, 2) seven subjects with acute, complete cervical SCI, and 3) six subjects with acute, incomplete cervical SCI. The individuals in groups 2 and 3 were studied at months 1, 3, and 12 postinjury, whereas individuals with chronic SCI were compared with an able-bodied control group. Chronic complete SCI was associated with a marked decrease in [(3)H]ouabain binding site concentration in skeletal muscle as well as reduced protein content of the α(1)-, α(2)-, and β(1)-subunit of the Na(+)-K(+)-ATPase. In line with this finding, expression of the Na(+)-K(+)-ATPase α(1)- and α(2)-subunits progressively decreased during the first year after complete but not after incomplete SCI. The expression of the regulatory protein phospholemman (PLM or FXYD1) was attenuated after complete, but not incomplete, cervical SCI. In contrast, FXYD5 was substantially upregulated in patients with complete SCI. In conclusion, the severity of the spinal cord lesion and the level of postinjury physical activity in patients with SCI are important factors controlling the expression of Na(+)-K(+)-ATPase and its regulatory proteins PLM and FXYD5.

Promotion of intramuscular fat accumulation in porcine muscle by nutritional regulation

Recently, pork with marbling has received attention as good quality pork and scientists are required to develop methods to produce pork with reasonable amounts of intramuscular fat (IMF). The aim of this review is to describe studies relevant to promotion of IMF accumulation in porcine muscle by nutritional regulation. The main focus is on effect of dietary lysine levels. First, we found dietary low lysine up-regulated glucose transporter protein 4 messenger (m)RNA expression in Longissimus dorsi (L. dorsi) and Rhomboideus muscles. In addition, the proportion of oxidative fiber of both muscles was also enhanced by dietary low lysine. Because it has been observed that higher oxidative capacity is associated with higher IMF content, we hypothesized that dietary low lysine would promote IMF accumulation. Further, higher mRNA abundance of peroxisome proliferator-activated receptor γ, a master regulator of adipogenesis, in both muscles induced by dietary low lysine, supported this hypothesis. Indeed, IMF content of L. dorsi muscle of finishing pigs given a low lysine diet for 2 months until reaching the market weight was twice that of pigs given a control diet. Possible underlying mechanisms of IMF accumulation in porcine muscle and future perspectives are also discussed in this review.

Differential expression of metabolic genes essential for glucose and lipid metabolism in skeletal muscle from spinal cord injured subjects

Skeletal muscle plays an important role in the regulation of energy homeostasis; therefore, the ability of skeletal muscle to adapt and alter metabolic gene expression in response to changes in physiological demands is critical for energy balance. Individuals with cervical spinal cord lesions are characterized by tetraplegia, impaired thermoregulation, and altered skeletal muscle morphology. We characterized skeletal muscle metabolic gene expression patterns, as well as protein content, in these individuals to assess the impact of spinal cord injury on critical determinants of skeletal muscle metabolism. Our results demonstrate that mRNA levels and protein expression of skeletal muscle genes essential for glucose storage are reduced, whereas expression of glycolytic genes is reciprocally increased in individuals with spinal cord injury. Furthermore, expression of genes essential for lipid oxidation is coordinately reduced in spinal cord injured subjects, consistent with a marked reduction of mitochondrial proteins. Thus spinal cord injury resulted in a profound and tightly coordinated change in skeletal muscle metabolic gene expression program that is associated with the aberrant metabolic features of the tissue.

Lower-extremity functional electrical stimulation decreases platelet aggregation and blood coagulation in persons with chronic spinal cord injury: a pilot study

BACKGROUND

Individuals with spinal cord injury (SCI) develop premature cardiovascular disease. Regular exercise reduces the incidence and symptoms of cardiovascular disease in able-bodied individuals; these salutary effects of exercise have not been documented in persons with SCI.

OBJECTIVE

To evaluate the effects of functional electrical stimulation leg cycle ergometry (FES-LCE) exercise training on platelet aggregation and blood coagulation in persons with SCI.

PARTICIPANTS

Subjects (n=14) with stable chronic (>1 year) paraplegia (T1-T10) or tetraplegia (C4-C8).

METHODS

Blood samples were collected before and after the first and eighth sessions (2 sessions per week for 4 weeks) of FES exercise.

RESULTS

Platelet aggregation was inhibited by 20% after the first session and by 40% (P < 0.001) after the eighth session. Thrombin activity was unchanged after the first session (10.7 +/- 0.85 s to 10.43 +/- 0.56 s) and decreased after the eighth session (12.5 +/- 1.98 s to 11.1 +/- 1.7 s; P < 0.0003). Antithrombin III activity increased after the first (103.8% +/- 8.9% to 110% +/- 6.9%; P < 0.0008) and eighth sessions (107.8% +/- 12.1% to 120.4% +/- 13.1%; P < 0.0001). Cyclic adenosine monophosphate increased after the first (9.9% + 2.5% to 15.8% +/- 3%; P < 0.001) and eighth sessions (17.8% +/- 4.2% to 36.5% +/- 7.6%; P < 0.0001). After the eighth session, factors V and X increased significantly (88% +/- 27% to 103% +/- 23%, P < 0.0001; 100% +/- 40% to 105% +/- 7%, P < 0.01, respectively); factors VII and VIII and fibrinogen did not change significantly. A significant reduction in platelet activation/aggregation was demonstrated in response to FES-LCE. The decrease in thrombin level was caused by the simultaneous increase in antithrombin activity.

CONCLUSION

These findings provide new insight into the potential protective effects of FES-LCE against the risk of cardiovascular disease.

Atrogin-1, MuRF1, and FoXO, as well as phosphorylated GSK-3beta and 4E-BP1 are reduced in skeletal muscle of chronic spinal cord-injured patients

Chronic complete spinal cord injury (SCI) is associated with severe skeletal muscle atrophy as well several atrophy and physical-inactivity-related comorbidity factors such as diabetes, obesity, lipid disorders, and cardiovascular diseases. Intracellular mechanisms associated with chronic complete SCI-related muscle atrophy are not well understood, and thus their characterization may assist with developing strategies to reduce the risk of comorbidity factors. Therefore, the aim of this study was to determine whether there was an increase in catabolic signaling targets, such as atrogin-1, muscle ring finger-1 (MuRF1), forkhead transcription factor (FoXO), and myostatin, and decreases in anabolic signaling targets, such as insulin-like growth factor (IGF), v-akt murine thymoma viral oncogene (Akt), glycogen synthase kinase-beta (GSK-3beta), mammalian target of rapamycin (mTOR), eukaryotic initiation factor 4E binding protein 1 (4E-BP1), and p70(s6kinase) in chronic complete SCI patients. In SCI patients, when compared with controls, there was a significant reduction in mRNA levels of atrogin-1 (59%; P < 0.05), MuRF1 (55%; P < 0.05), and myostatin (46%; P < 0.01), and in protein levels of FoXO1 (72%; P < 0.05), FoXO3a (60%; P < 0.05), and atrogin-1 (36%; P < 0.05). Decreases in the protein levels of IGF-1 (48%; P < 0.001) and phosphorylated GSK-3beta (54%; P < 0.05), 4E-BP1 (48%; P < 0.05), and p70(s6kinase) (60%; P = 0.1) were also observed, the latter three in an Akt- and mTOR-independent manner. Reductions in atrogin-1, MuRF1, FoXO, and myostatin suggest the existence of an internal mechanism aimed at reducing further loss of muscle proteins during chronic SCI. The downregulation of signaling proteins that regulate anabolism, such as IGF, GSK-3beta, and 4E-BP1, would reduce the ability to increase protein synthesis rates.

Effect of exercise on disorders of carbohydrate and lipid metabolism in adults with traumatic spinal cord injury: systematic review of the evidence

BACKGROUND/OBJECTIVE

Carbohydrate and lipid metabolism disorders may affect adults with spinal cord injuries (SCIs) differently than able-bodied individuals because of reduced physical activity in the SCI population. The objective of this study was to conduct a systematic review to determine the effectiveness of exercise to improve carbohydrate and lipid metabolism disorders in adults with chronic SCI.

METHODS

Studies were identified in MEDLINE (1996-2008), Cochrane Library, bibliographies of identified articles, and expert recommendations. English language articles were included if they evaluated adults with chronic SCI; evaluated exercise; and reported carbohydrate-, lipid-, and/or cardiovascular disease-related outcomes.

RESULTS

Twenty-two studies met inclusion criteria, including 15 intervention case-series and 7 cross-sectional surveys using self-reported physical activity measures. Intervention protocols involved active (n=7) or electrically stimulated (n=7) exercise or an educational program (n ) from 8 to 52 weeks in duration. Frequency of exercise was typically 2 to 3 sessions/week, lasting 30 to 60 minutes/session. Totals of 150 and 369 subjects participated in studies with carbohydrate (n=12) or lipid and cardiovascular (n=16) outcomes, respectively; 78% were men. Level of SCI ranged from C4 to L5 and included both incomplete and complete lesions. Outcomes measures included fasting and postload blood glucose and insulin concentrations and serum cholesterol levels. Small sample sizes and variations in study design, intervention, SCI characteristics, and reported outcomes precluded quantitative pooling of results or reliable assessment of metabolic efficacy. No intervention studies assessed cardiovascular outcomes.

CONCLUSIONS

Evidence is insufficient to determine whether exercise improves carbohydrate and lipid metabolism disorders among adults with SCI. Expert consensus, based on the preliminary evidence, is needed to inform future studies.

The beneficial effects of nettle supplementation and exercise on brain lesion and memory in rat

Regular swimming and phytotherapeutic supplementation are assumed to alleviate the severity of neurodegeneration leading to dementia. The effect of swimming training and that of enriched lab chow containing 1% (w/w) dried nettle (Urtica dioica) leaf on the prevention of severity of brain injury caused by N-methyl-d-aspartate (NMDA) lesion in Wistar rats were investigated. Nettle supplementation and regular swimming exercise seem to improve the adverse effect of brain injury caused by NMDA lesion assessed by passive avoidance test and open-field test. Nettle supplementation decreases the level of reactive oxygen species, measured by electron paramagnetic resonance, and the DNA-binding activity of NF-kappaB. The data reveal that nettle supplementation has an effective antioxidant role, down-regulates the inflammatory transcription factors and could also promote learning performance in the brain. Regular swimming increases the concentration of reactive species in the cerebellum and alters the activity of transcription factors toward inflammation. The additive effect of the two treatments was more profound in the down-regulation of inflammatory transcription processes in NMDA lesion.

Testosterone and DHEA activate the glucose metabolism-related signaling pathway in skeletal muscle

Circulating dehydroepiandrosterone (DHEA) is converted to testosterone or estrogen in the target tissues. Recently, we demonstrated that skeletal muscles are capable of locally synthesizing circulating DHEA to testosterone and estrogen. Furthermore, testosterone is converted to 5alpha-dihydrotestosterone (DHT) by 5alpha-reductase and exerts biophysiological actions through binding to androgen receptors. However, it remains unclear whether skeletal muscle can synthesize DHT from testosterone and/or DHEA and whether these hormones affect glucose metabolism-related signaling pathway in skeletal muscles. We hypothesized that locally synthesized DHT from testosterone and/or DHEA activates glucose transporter-4 (GLUT-4)-regulating pathway in skeletal muscles. The aim of the present study was to clarify whether DHT is synthesized from testosterone and/or DHEA in cultured skeletal muscle cells and whether these hormones affect the GLUT-4-related signaling pathway in skeletal muscles. In the present study, the expression of 5alpha-reductase mRNA was detected in rat cultured skeletal muscle cells, and the addition of testosterone or DHEA increased intramuscular DHT concentrations. Addition of testosterone or DHEA increased GLUT-4 protein expression and its translocation. Furthermore, Akt and protein kinase C-zeta/lambda (PKC-zeta/lambda) phosphorylations, which are critical in GLUT-4-regulated signaling pathways, were enhanced by testosterone or DHEA addition. Testosterone- and DHEA-induced increases in both GLUT-4 expression and Akt and PKC-zeta/lambda phosphorylations were blocked by a DHT inhibitor. Finally, the activities of phosphofructokinase and hexokinase, main glycolytic enzymes, were enhanced by testosterone or DHEA addition. These findings suggest that skeletal muscle is capable of synthesizing DHT from testosterone, and that DHT activates the glucose metabolism-related signaling pathway in skeletal muscle cells.

Functional electrical stimulation cycling improves body composition, metabolic and neural factors in persons with spinal cord injury

Persons with spinal cord injury (SCI) are at a heightened risk of developing type II diabetes and cardiovascular disease. The purpose of this investigation was to conduct an analysis of metabolic, body composition, and neurological factors before and after 10 weeks of functional electrical stimulation (FES) cycling in persons with SCI. Eighteen individuals with SCI received FES cycling 2-3 times per week for 10 weeks. Body composition was analyzed by dual X-ray absorptiometry. The American Spinal Injury Association (ASIA) neurological classification of SCI test battery was used to assess motor and sensory function. An oral glucose tolerance (OGTT) and insulin-response test was performed to assess blood glucose control. Additional metabolic variables including plasma cholesterol (total-C, HDL-C, LDL-C), triglyceride, and inflammatory markers (IL-6, TNF-alpha, and CRP) were also measured. Total FES cycling power and work done increased with training. Lean muscle mass also increased, whereas, bone and adipose mass did not change. The ASIA motor and sensory scores for the lower extremity significantly increased with training. Blood glucose and insulin levels were lower following the OGTT after 10 weeks of training. Triglyceride levels did not change following training. However, levels of IL-6, TNF-alpha, and CRP were all significantly reduced.

Clinical assessment and management of obesity in individuals with spinal cord injury: a review

BACKGROUND

Diagnosing and managing obesity in individuals with spinal cord injury (SCI) remain challenging.

METHODS

Literature on the epidemiology, impact, and management of obesity in individuals with SCI was reviewed.

FINDINGS

Although nearly 66% of individuals with SCI are either overweight or obese, little guidance is available to measure and monitor obesity in the clinical setting. The use of anthropometric indices and specific cut points available for able-bodied persons is limited by the body composition changes that follow SCI. Indices of upper body obesity warrant examination in SCI because they provide an index of central obesity, which is more closely linked to some obesity-related conditions than is overall obesity. Investigations into the sequelae of excess body fat and its distribution are also needed in SCI because past research in this area has been inconclusive. Although limited, evidence regarding obesity interventions in SCI may be promising.

CONCLUSIONS

The best anthropometric tool to define obesity in the clinical setting remains unknown. SCI-specific assessment tools and a better understanding of the sequelae of excess body weight will lead to better targeting of prevention and treatment efforts. More research is needed on the individual components of a weight management program unique to SCI. Until then, providers are urged to use a team approach and draw on existing resources and applicable research in able-bodied individuals to facilitate weight management in individuals with SCI.

Effects of endurance exercise training on insulin signaling in human skeletal muscle: interactions at the level of phosphatidylinositol 3-kinase, Akt, and AS160

The purpose of this study was to investigate the mechanisms explaining improved insulin-stimulated glucose uptake after exercise training in human skeletal muscle. Eight healthy men performed 3 weeks of one-legged knee extensor endurance exercise training. Fifteen hours after the last exercise bout, insulin-stimulated glucose uptake was approximately 60% higher (P < 0.01) in the trained compared with the untrained leg during a hyperinsulinemic-euglycemic clamp. Muscle biopsies were obtained before and after training as well as after 10 and 120 min of insulin stimulation in both legs. Protein content of Akt1/2 (55 +/- 17%, P < 0.05), AS160 (25 +/- 8%, P = 0.08), GLUT4 (52 +/- 19%, P < 0.001), hexokinase 2 (HK2) (197 +/- 40%, P < 0.001), and insulin-responsive aminopeptidase (65 +/- 15%, P < 0.001) increased in muscle in response to training. During hyperinsulinemia, activities of insulin receptor substrate-1 (IRS-1)-associated phosphatidylinositol 3-kinase (PI3-K) (P < 0.005), Akt1 (P < 0.05), Akt2 (P < 0.005), and glycogen synthase (GS) (percent I-form, P < 0.05) increased similarly in both trained and untrained muscle, consistent with increased phosphorylation of Akt Thr(308), Akt Ser(473), AS160, glycogen synthase kinase (GSK)-3alpha Ser(21), and GSK-3beta Ser(9) and decreased phosphorylation of GS site 3a+b (all P < 0.005). Interestingly, training improved insulin action on thigh blood flow, and, furthermore, in both basal and insulin-stimulated muscle tissue, activities of Akt1 and GS and phosphorylation of AS160 increased with training (all P < 0.05). In contrast, training reduced IRS-1-associated PI3-K activity (P < 0.05) in both basal and insulin-stimulated muscle tissue. Our findings do not support generally improved insulin signaling after endurance training; rather it seems that improved insulin-stimulated glucose uptake may result from hemodynamic adaptations as well as increased cellular protein content of individual insulin signaling components and molecules involved in glucose transport and metabolism.

Cardiovascular Health and Exercise Rehabilitation in Spinal Cord Injury

There appears to be an increased prevalence and earlier onset of cardiovascular disease (CVD) in persons with SCI. Physical inactivity is thought to be a key factor in the increased risk for CVD. Physical inactivity is highly prevalent in persons with SCI and it appears that activities of daily living are not sufficient to maintain cardiovascular fitness and health. This systematic review examines the current literature regarding the risk for CVD and the effectiveness of varied exercise rehabilitation programs in attenuating the risk for CVD in SCI.

Nur77 coordinately regulates expression of genes linked to glucose metabolism in skeletal muscle

Innervation is important for normal metabolism in skeletal muscle, including insulin-sensitive glucose uptake. However, the transcription factors that transduce signals from the neuromuscular junction to the nucleus and affect changes in metabolic gene expression are not well defined. We demonstrate here that the orphan nuclear receptor Nur77 is a regulator of gene expression linked to glucose utilization in muscle. In vivo, Nur77 is preferentially expressed in glycolytic compared with oxidative muscle and is responsive to beta-adrenergic stimulation. Denervation of rat muscle compromises expression of Nur77 in parallel with that of numerous genes linked to glucose metabolism, including glucose transporter 4 and genes involved in glycolysis, glycogenolysis, and the glycerophosphate shuttle. Ectopic expression of Nur77, either in rat muscle or in C2C12 muscle cells, induces expression of a highly overlapping set of genes, including glucose transporter 4, muscle phosphofructokinase, and glycogen phosphorylase. Furthermore, selective knockdown of Nur77 in rat muscle by small hairpin RNA or genetic deletion of Nur77 in mice reduces the expression of a battery of genes involved in skeletal muscle glucose utilization in vivo. Finally, we show that Nur77 binds the promoter regions of multiple genes involved in glucose metabolism in muscle. These results identify Nur77 as a potential mediator of neuromuscular signaling in the control of metabolic gene expression.

Distribution patterns of the glucose transporters GLUT4 and GLUT1 in skeletal muscles of rats (Rattus norvegicus), pigs (Sus scrofa), cows (Bos taurus), adult goats, goat kids (Capra hircus), and camels (Camelus dromedarius)

Earlier studies demonstrated that forestomach herbivores are less insulin sensitive than monogastric omnivores. The present study was carried out to determine if different distribution patterns of the glucose transporters GLUT1 and GLUT4 may contribute to these different insulin sensitivities. Western blotting was used to measure GLUT1 and GLUT4 protein contents in oxidative (masseter, diaphragm) and glycolytic (longissimus lumborum, semitendinosus) skeletal muscle membranes of monogastric omnivores (rats and pigs), and of forestomach herbivores (cows, adult goats, goat kids, and camels). Muscles were characterized biochemically. Comparing red and white muscles, the isocitrate dehydrogenase (ICDH) activity was 1.5-15-times higher in oxidative muscles of all species, whereas lactate dehydrogenase (LDH) activity was 1.4-4.4-times higher in glycolytic muscles except in adult goats. GLUT4 levels were 1.5-6.3-times higher in oxidative muscles. GLUT1 levels were 2.2-8.3-times higher in glycolytic muscles in forestomach herbivores but not in monogastric animals. We conclude that GLUT1 may be the predominant glucose transporter in glycolytic muscles of ruminating animals. The GLUT1 distribution patterns were identical in adult and pre-ruminant goats, indicating that GLUT1 expression among these muscles is determined genetically. The high blood glucose levels of camels cited in literature may be due to an "NIDDM-like" impaired GLUT4 activity in skeletal muscle.