Ashraf S. Gorgey

Effects of Resistance Training on Adiposity and Metabolism after Spinal Cord Injury

PURPOSE This pilot work was conducted to evaluate the effects of neuromuscular electrical stimulation resistance training (RT) of the paralyzed knee extensor muscle groups on skeletal muscle and intramuscular fat (IMF) cross-sectional areas, trunk visceral adipose tissue (VAT), carbohydrate, and lipid profiles in men with spinal cord injury. METHODS Nine individuals with motor complete spinal cord injury were randomly assigned to an RT + diet group (n = 5) or a diet group (n = 4). The RT + diet underwent 12 wk of progressive RT, twice weekly, to the knee extensor muscle groups using neuromuscular electrical stimulation and ankle weights. Weekly feedback was provided to both groups to maintain a standard diet. Magnetic resonance imaging and a whole-body dual-energy x-ray absorptiometric images were obtained before and 1 wk after interventions. Participants underwent a metabolic study after a 12-h overnight fast to measure fasting and postchallenge plasma glucose, insulin, and lipid profiles. RESULTS Skeletal muscle hypertrophy was detected in the whole thigh, knee extensors, and flexors in the RT + diet group compared with the diet group. VAT cross-sectional area, VAT/subcutaneous adipose tissue ratio at L5-S3, and percent IMF decreased significantly in the RT + diet group. Plasma insulin area under the curve decreased in the RT + diet group but not in the diet group. Fasting triglycerides and cholesterol/HDL decreased in the RT + diet group. CONCLUSIONS Twice-weekly evoked RT to the paralyzed lower extremities resulted in significant skeletal muscle hypertrophy that was associated with reduction in VAT, VAT/subcutaneous adipose tissue ratio, and percent IMF. Significant improvements in insulin profile and lipid metabolism were noted in the RT + diet when compared with diet alone.

Effects of Electrical Stimulation Parameters on Fatigue in Skeletal Muscle

STUDY DESIGN Experimental laboratory study. OBJECTIVES The primary purpose was to investigate the independent effects of current amplitude, pulse duration, and current frequency on muscle fatigue during neuromuscular electrical stimulation (NMES). A second purpose was to determine if the ratio of the evoked torque to the activated area could explain muscle fatigue. BACKGROUND Parameters of NMES have been shown to differently affect the evoked torque and the activated area. The efficacy of NMES is limited by the rapid onset of muscle fatigue. METHODS AND MEASURES Seven healthy participants underwent 4 NMES protocols that were randomly applied to the knee extensor muscle group. The NMES protocols were as follows: standard protocol (Std), defined as 100-Hz, 450-micros pulses and amplitude set to evoke 75% of maximal voluntary isometric torque (MVIT); short pulse duration protocol (SP), defined as 100-Hz, 150-micros pulses and amplitude set to evoke 75% of MVIT; low-frequency protocol (LF), defined as 25-Hz, 450-micros pulses and amplitude set to evoke 75% of MVIT; and low-amplitude protocol (LA), defined as 100-Hz, 450-micros pulses and amplitude set to evoke 45% of MVIT. The peak torque was measured at the start and at the end of the 4 protocols, and percent fatigue was calculated. The outcomes of the 4 NMES protocols on the initial peak torque and activated cross-sectional area were recalculated from a companion study to measure torque per active area. RESULTS Decreasing frequency from 100 to 25 Hz decreased fatigue from 76% to 39%. Decreasing the amplitude and pulse duration resulted in no change of muscle fatigue. Torque per active area accounted for 57% of the variability in percent fatigue between Std and LF protocols. CONCLUSIONS Altering the amplitude of the current and pulse duration does not appear to influence the percent fatigue in NMES. Lowering the stimulation frequency results in less fatigue, by possibly reducing the evoked torque relative to the activated muscle area.

Effects of spinal cord injury on body composition and metabolic profile – Part I

Abstract Several body composition and metabolic-associated disorders such as glucose intolerance, insulin resistance, and lipid abnormalities occur prematurely after spinal cord injury (SCI) and at a higher prevalence compared to able-bodied populations. Within a few weeks to months of the injury, there is a significant decrease in total lean mass, particularly lower extremity muscle mass and an accompanying increase in fat mass. The infiltration of fat in intramuscular and visceral sites is associated with abnormal metabolic profiles. The current review will summarize the major changes in body composition and metabolic profiles that can lead to comorbidities such as type 2 diabetes mellitus and cardiovascular diseases after SCI. It is crucial for healthcare specialists to be aware of the magnitude of these changes. Such awareness may lead to earlier recognition and treatment of metabolic abnormalities that may reduce the co-morbidities seen over the lifetime of persons living with SCI.

Central adiposity associations to carbohydrate and lipid metabolism in individuals with complete motor spinal cord injury.

Altered body composition has been suggested as a major factor for the high prevalence of impaired glucose tolerance, insulin resistance, and dyslipidemia in individuals with spinal cord injury (SCI). The contributions of visceral adipose tissue (VAT), trunk subcutaneous adipose tissue (SAT), and the VAT/SAT ratio to these metabolic derangements in SCI are poorly defined. Thirteen individuals with traumatic motor complete SCI underwent a metabolic study after overnight fasting to measure plasma glucose, insulin, and lipid concentrations. Fast spin echo magnetic resonance imaging was used to quantify the average cross-sectional area (CSA), volumes, and percentages of VAT and SAT across multiaxial slices. Dual-energy x-ray absorptiometry was performed to measure whole-body fat-free mass and fat mass. Visceral adipose tissue CSA was positively related to fasting plasma glucose (r = 0.77, P = .002) and to the ratio of cholesterol to high-density lipoproteins (HDL-C) (r = 0.71, P = .006). Visceral adipose tissue volume was related to total cholesterol (r = 0.57, P = .043) and to low-density lipoproteins (r = 0.59, P = .032). Trunk %SAT was negatively related to glucose concentration and area under the curve (both, r = -0.61, P = .026). Fasting plasma insulin was negatively related to the VAT CSA and VAT/SAT ratio (both, r = -0.57, P = .043). Partial correlations showed a negative association between trunk %SAT and glucose area under the curve (r = -0.61, P = .02) and a positive association with HDL-C (r = 0.64, P = .033). The findings suggest that an increase in VAT, SAT, and VAT/SAT is associated with the adverse metabolic profile commonly seen in individuals with SCI. Trunk %SAT is associated with a reduced risk of glucose intolerance and an increased HDL-C.

Skeletal Muscle Hypertrophy and Decreased Intramuscular Fat After Unilateral Resistance Training in Spinal Cord Injury: Case Report

Abstract Background: Skeletal muscle atrophy is a common adaptation after spinal cord injury (SCI) that results in numerous health-related complications. Neuromuscular electrical stimulation (NMES) has been recognized as an effective tool, which attenuates atrophy and evokes hypertrophy. Objective: To investigate the effects of NMES resistance training (RT) on individual muscle groups and adipose tissue of the right thigh after stimulation of the knee extensor muscle group in a man with chronic SCI. Participant: A 22-year-old man with a complete SCI sustained in a motorcycle accident 5 years prior to participation in this study. Methods: The participant underwent training twice a week for 12 weeks, including unilateral progressive RT of the right knee extensor muscle group using NMES and ankle weights. The stimulation was applied to knee extensors while the participant was sitting in his wheelchair. A series of T1 -weighted magnetic resonance images were acquired for the whole right thigh prior to and after training. Skeletal muscle cross- sectional areas were measured of the whole thigh, knee extensors, hip adductors, hamstrings, and sartorius and gracilis muscle groups. Additionally, intramuscular fat and subcutaneous fat of the thigh were measured. Results: At the end of 12 weeks, the participant was able to lift 17 lbs during full knee extension. Average skeletal muscle cross-sectional areas increased in all of the measured muscle groups (12%-43%). Hypertrophy ranging from 30% to 112% was detected in multiaxial slices after the NMES RT protocol. Intramuscular fat decreased by more than 50% and subcutaneous fat increased by 24%. Conclusion: Unilateral NMES RT protocol evoked hypertrophy in the knee extensor and adjacent skeletal muscle groups and was associated with a reduction in intramuscular fat in a person with a chronic SCI. Additionally, subcutaneous adipose tissue cross-sectional areas increased in response to RT.

Relationship of spasticity to soft tissue body composition and the metabolic profile in persons with chronic motor complete spinal cord injury.

Abstract Background/Objective: To determine the effects of spasticity on anthropometrics, body composition (fat mass [FM] and fat-free mass [FFM]), and metabolic profile (energy expenditure, plasma glucose, insulin concentration, and lipid panel) in individuals with motor complete spinal cord injury (SCI). Methods: Ten individuals with chronic motor complete SCI (age, 33 ± 7 years; BMI, 24 ± 4 kg/m2; level of injury, C6—T11; American Spinal Injury Association A and B) underwent waist and abdominal circumferences to measure trunk adiposity. After the first visit, the participants were admitted to the general clinical research center for body composition (FFM and FM) assessment using dual energy x-ray absorptiometry. After overnight fasting, resting metabolic rate (RMR) and metabolic profile (plasma glucose, insulin, and lipid profile) were measured. Spasticity of the hip, knee, and ankle flexors and extensors was measured at 6 time points over 24 hours using the Modified Ashworth Scale. Results: Knee extensor spasticity was negatively correlated to abdominal circumferences (r = -0.66, P = 0.038). After accounting for leg or total FFM, spasticity was negatively related to abdominal circumference (r = -0.67, P = 0.03). Knee extensor spasticity was associated with greater total %FFM (r = 0.64; P = 0.048), lower %FM (r = -0.66; P = 0.03), and lower FM to FFM ratio. Increased FFM (kg) was associated with higher RMR (r = 0.89; P = 0.0001). Finally, spasticity may indirectly influence glucose homeostasis and lipid profile by maintaining FFM (r = -0.5 to -0.8, P < 0.001). Conclusion: Significant relationships were noted between spasticity and variables of body composition and metabolic profile in persons with chronic motor complete SCI, suggesting that spasticity may play a role in the defense against deterioration in these variables years after injury. The exact mechanism is yet to be determined.

The Role of Pulse Duration and Stimulation Duration in Maximizing the Normalized Torque During Neuromuscular Electrical Stimulation

STUDY DESIGN Controlled laboratory study OBJECTIVES To determine the effects of pulse duration and stimulation duration on the evoked torque after controlling for the activated area by using magnetic resonance imaging (MRI). BACKGROUND Neuromuscular electrical stimulation (NMES) is commonly used in the clinic without considering the physiological implications of its parameters. METHODS AND MEASURES Seven able-bodied, college students (mean +/- SD age, 28 +/- 4 years) participated in this study. Two NMES protocols were applied to the knee extensor muscle group in a random order. Protocol A applied 100-Hz, 450-microsecond pulses for 5 minutes in a 3-seconds-on 3-seconds-off duty cycle. Protocol B applied 60-Hz, 250-microsecond pulses for 5 minutes in a 10-seconds-on 20-seconds-off duty cycle. The amplitude of the current was similar in both protocols. Torque, torque time integral, and normalized torque for the knee extensors were measured for both protocols. MRI scans were taken prior to, and immediately after, each protocol to measure the cross-sectional area of the stimulated muscle. RESULTS The skeletal muscle cross-sectional areas activated after both protocols were similar. The longer pulse duration in protocol A elicited 22% greater torque output than that of protocol B (P<.05). After considering the activated area in both protocols, the normalized torque with protocol A was 38% greater than that with protocol B (P<.05). Torque time integral was 21% greater with protocol A (P = .029). Protocol B failed to maintain torque at the start and the end of the 10-second activation. CONCLUSIONS Longer pulse duration, but not stimulation duration, resulted in a greater evoked and normalized torque compared to the shorter pulse duration, even after controlling for the activated muscular cross-sectional areas with both protocols. LEVEL OF EVIDENCE Therapy, level 5.

Functional electrical stimulation therapies after spinal cord injury.

The use of electricity for therapeutic purposes dates back to 15 AD, when Scribonius Largus, a court physician to the Roman emperor Claudius began using electric shocks from the torpedo ray fish to treat gout pain and headaches [1]. Although the phenomenon of electricity had been used for centuries the actual word “electricity” was not in use until the 1600’s, when William Gilbert, an English physician, coined the new Latin word “electricus” meaning like amber. The Creek word amber refers to the property of attracting small objects after being rubbed [2]. In 1780, Luigi Galvani, an Italian physician and physicist showed that impulses from nerve cells pass to muscles by demonstrating the electrical stimulation of a frog’s leg muscles [3]. Italian physicist and nephew of Luigi Galvani, Giovanni Aldini, carried on the work of his uncle by demonstrating the ability to stimulate brain tissue by applying electrical stimulation to the heads of decapitated prisoners [4]. In 1874, physician Robert Bartholow, stimulated muscle contractions while working on the cancerous brain of a live woman [5]. Research into the uses of electricity continued through the 19th and 20th centuries allowing the development of numerous inventions i.e. galvanometer, micro-electrodes, cathode ray oscilloscope, pacemakers and defibrillators [6,7]. These and other advances

Influence of motor complete spinal cord injury on visceral and subcutaneous adipose tissue measured by multi-axial magnetic resonance imaging

Abstract Objective: Abdominal obesity conveys substantial health risks, in association with high levels of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and an increased proportion of VAT to SAT. The purposes were to determine the influence of spinal cord injury (SCI) on the associations between single axial cross-sectional area (CSA) slices and the average CSA or volumes of VAT and SAT across multi-axial slices of magnetic resonance imaging (MRI); and the relationships relative to the whole body composition and anthropometrics. Methods: Thirteen healthy male participants with traumatic motor complete SCI underwent fast spin-echo MRI to measure VAT and SAT across multi-axial slices, followed by dual-energy X-ray absorptiometry to measure whole body fat-free mass (FFM) and fat mass (FM). Waist circumference (WC) was also measured in the seated position. Results: The trunk CSAs of VAT and SAT were 99 ± 51 and 164 ± 69 cm2, respectively, and the ratio of VAT to SAT was 0.68 ± 0.33. The CSAs of VAT and SAT at a single slice strongly predicted the average CSA and modestly predicted the volumes across multi-axial slices. VAT and SAT represented 5.7 ± 1.8% and 9.7 ± 3.2% of the total body FM, respectively. Percent body FFM was negatively related to VAT and SAT volumes, but not to a single axial CSA. Conclusion: A single slice CSA can modestly predict the volume of multi-axial slices in individuals with SCI, yet it is not related to any of the body composition variables. Increased percent FFM is associated with a reduction in VAT and SAT volumes measured across multi-axial slices. The ratio of VAT to SAT is greater than 0.4, suggesting that individuals with SCI are at high risk of developing metabolic sequelae.

Prevalence of Obesity After Spinal Cord Injury

The prevalence of obesity has been continuously increasing in the United States. Obesity has crossed the borders of the able-bodied populations and extended to populations with disabilities, including spinal cord injury (SCI). The magnitude and the prevalence of obesity after SCI are not clearly defined. The purpose of the current review is to discuss the body of literature on the prevalence of obesity among individuals with SCI. The review will show that the prevalence of obesity after SCI is an issue that needs to be further addressed and specifically correlated to mortality rates in SCI. Body mass index (BMI) criteria need to be adjusted to meet the changes in body composition after SCI, specifically increasing fat mass and percent body fat. Prevalence of overweight and obesity in SCI by sex, age, and ethnic group needs further investigation to determine the actual magnitude of the problem, which appears to exceed epidemic proportions. Moreover, SCI-specific factors such as level of injury, American Spinal Injury Association (ASIA) impairment classification, and time since injury need to be further correlated to the prevalence of obesity after SCI.