Rodney C. Wade

Mitochondrial mass and activity as a function of body composition in individuals with spinal cord injury

Spinal cord injury (SCI) is accompanied by deterioration in body composition and severe muscle atrophy. These changes put individuals at risk for insulin resistance, type II diabetes, and cardiovascular disease. To determine the relationships between skeletal muscle mitochondrial mass, activity, and body composition, 22 men with motor complete SCI were studied. Body composition assessment was performed using dual‐energy X‐ray absorptiometry and magnetic resonance imaging. Skeletal muscle biopsies were obtained from the vastus lateralis muscle to measure citrate synthase (CS) and complex III (CIII) activity. CS activity was inversely related to %body fat (r = −0.57, P = 0.013), %leg fat (r = −0.52, P = 0.027), %trunk fat (r = −0.54, P = 0.020), and %android fat (r = −0.54, P = 0.017). CIII activity was negatively related to %body fat (r = −0.58, P = 0.022) and %leg fat (r = −0.54, P = 0.037). Increased visceral adipose tissue was associated with decreased CS and CIII activity (r = −0.66, P = 0.004; r = −0.60, P = 0.022). Thigh intramuscular fat was also inversely related to both CS and CIII activity (r = −0.56, P = 0.026; r = −0.60, P = 0.024). Conversely, lean mass (r = 0.75, P = 0.0003; r = 0.65, P = 0.008) and thigh muscle cross‐sectional area (CSA; r = 0.82, P = 0.0001; r = 0.84; P = 0.0001) were positively related to mitochondrial parameters. When normalized to thigh muscle CSA, many body composition measurements remained related to CS and CIII activity, suggesting that %fat and lean mass may predict mitochondrial mass and activity independent of muscle size. Finally, individuals with SCI over age 40 had decreased CS and CIII activity (P = 0.009; P = 0.004), suggesting a decrease in mitochondrial health with advanced age. Collectively, these findings suggest that an increase in adipose tissue and decrease in lean mass results in decreased skeletal muscle mitochondrial activity in individuals with chronic SCI.

Neuromuscular electrical stimulation and testosterone did not influence heterotopic ossification size after spinal cord injury: A case series.

Neuromuscular electrical stimulation (NMES) and testosterone replacement therapy (TRT) are effective rehabilitation strategies to attenuate muscle atrophy and evoke hypertrophy in persons with spinal cord injury (SCI). However both interventions might increase heterotopic ossification (HO) size in SCI patients. We present the results of two men with chronic traumatic motor complete SCI who also had pre-existing HO and participated in a study investigating the effects of TRT or TRT plus NMES resistance training (RT) on body composition. The 49-year-old male, Subject A, has unilateral HO in his right thigh. The 31-year-old male, Subject B, has bilateral HO in both thighs. Both participants wore transdermal testosterone patches (4-6 mg/d) daily for 16 wk. Subject A also underwent progressive NMES-RT twice weekly for 16 wk. Magnetic resonance imaging scans were acquired prior to and post intervention. Cross-sectional areas (CSA) of the whole thigh and knee extensor skeletal muscles, femoral bone, and HO were measured. In Subject A (NMES-RT + TRT), the whole thigh skeletal muscle CSA increased by 10%, the knee extensor CSA increased by 17%, and the HO + femoral bone CSA did not change. In Subject B (TRT), the whole thigh skeletal muscle CSA increased by 13% in the right thigh and 6% in the left thigh. The knee extensor CSA increased by 7% in the right thigh and did not change in the left thigh. The femoral bone and HO CSAs in both thighs did not change. Both the TRT and NMES-RT + TRT protocols evoked muscle hypertrophy without stimulating the growth of pre-existing HO.

A feasibility pilot using telehealth videoconference monitoring of home-based NMES resistance training in persons with spinal cord injury

Introduction:The objective of the study was to investigate the feasibility and initial efficacy of telehealth communication in conjunction with surface neuromuscular electrical stimulation (NMES) resistance training (RT) to induce muscle hypertrophy.Materials and Methods:This was a home-based setting of within-subject control design of trained vs controlled limbs. Five men with chronic (>1 year postinjury) motor-complete spinal cord injury (SCI) participated in a twice-weekly telehealth videoconference program using home-based NMES-RT for 8 weeks. Stimulation was applied to the knee extensor muscle group of the trained leg, while the untrained leg served as a control. Participants received real-time feedback to ensure a proper setup of electrodes and stimulator to monitor subject safety throughout the entire training session. Magnetic resonance imaging was used to measure cross-sectional areas (CSAs) and intramuscular fat (IMF) of the whole thigh and individual muscle groups. Average two-way travel time, distance traveled in miles and total cost of gas per mile were calculated.Results:Participants had 100% compliance. Trained whole and absolute knee extensor muscle CSA increased by 13% (P=0.002) and 18% (P=0.0002), with no changes in the controlled limb. Absolute knee flexor and adductor CSAs increased by 3% (P=0.02) and 13% (P=0.0001), respectively. Absolute whole thigh and knee extensor IMF CSAs decreased significantly in the trained limb by 14% (P=0.01) and 36% (P=0.0005), respectively, with no changes in controlled limb.Discussion:The pilot work documented that using telehealth communication is a safe, feasible and potentially cost-reducing approach for monitoring home-based NMES-RT in persons with chronic SCI. All trained muscles showed detectable muscle hypertrophy with concomitant decrease in ectopic adipose tissue.

Anthropometric prediction of skeletal muscle cross-sectional area in persons with spinal cord injury

Finding an accurate and affordable method to quantify muscle size following spinal cord injury (SCI) could provide benefits clinically and in research settings. The purpose of this study was to validate the use of anthropometric measurements vs. magnetic resonance imaging (MRI) to evaluate muscle cross-sectional area (CSA) and develop a field equation to predict muscle CSA specific to the SCI population. Twenty-two men with chronic (>1 yr) motor complete SCI participated in the current study. Anthropometric measurements, including midthigh circumference and anterior skinfold thickness (SFT), were taken on the right thigh. The anthropometric muscle cross-sectional area (muscle CSAanthro) was predicted using the following equation: muscle CSAanthro = π[r - (SFT/2)]2, where r = thigh circumference/2π. MRI analysis yielded whole thigh CSA (thigh CSAMRI), midthigh muscle CSA (muscle CSAMRI), midthigh absolute muscle CSA after subtracting intramuscular fat and bone (muscle CSA-IMFMRI), subcutaneous adipose tissue (SATT) measured at one site as well as at four sites, and bone CSA. Anthropometric measurements were correlated to the thigh CSAMRI [r2 = 0.90, standard error of the estimate (SEE) = 17.6 cm2, P < 0.001]. Muscle CSAanthro was correlated to muscle CSAMRI (r2 = 0.78, SEE = 16.6 cm2, P < 0.001) and muscle CSA-IMFMRI (r2 = 0.75, SEE = 17.6 cm2, P < 0.001). A single SFT was correlated to the polar four-site SATT (r2 = 0.78, SEE = 0.37 cm, P < 0.001). The average femur CSA and average IMF CSA derived from MRI led to the following field equation: muscle CSApredicted = π[(Thighcircum/2π) - (SFT/2)]2 - 23.2. Anthropometric measurements of muscle CSA exhibited a good agreement with the gold standard MRI method and led to the development of a field equation for clinical use after accounting for bone and IMF.NEW & NOTEWORTHY This study used anthropometric measurements and magnetic resonance imaging (MRI) to evaluate muscle cross-sectional area (CSA) and developed a field equation to predict thigh muscle CSA specific to the spinal cord-injured (SCI) population. Anthropometric measurements were correlated to the whole thigh CSA and muscle CSA as measured by MRI. The correlations led to the development of a SCI-specific field equation that accounted for intramuscular fat and bone areas.

Exoskeleton Training May Improve Level of Physical Activity After Spinal Cord Injury: A Case Series

Objectives: To determine whether the use of a powered exoskeleton can improve parameters of physical activity as determined by walking time, stand up time, and number of steps in persons with spinal cord injury (SCI). Methods: Three men with complete (1 C5 AIS A and 2 T4 AIS A) and one man with incomplete (C5 AIS D) SCI participated in a clinical rehabilitation program. In the training program, the participants walked once weekly using a powered exoskeleton (Ekso) for approximately 1 hour over the course of 10 to 15 weeks. Walking time, stand up time, ratio of walking to stand up time, and number of steps were determined. Oxygen uptake (L/min), energy expenditure, and body composition were measured in one participant after training. Results: Over the course of 10 to 15 weeks, the maximum walking time increased from 12 to 57 minutes and the number of steps increased from 59 to 2,284 steps. At the end of the training, the 4 participants were able to exercise for 26 to 59 minutes. For one participant, oxygen uptake increased from 0.27 L/min during rest to 0.55 L/min during walking. Maximum walking speed was 0.24 m/s, and delta energy expenditure increased by 1.4 kcal/min during walking. Body composition showed a modest decrease in absolute fat mass in one participant. Conclusion: Exoskeleton training may improve parameters of physical activity after SCI by increasing the number of steps and walking time. Other benefits may include increasing energy expenditure and improving the profile of body composition.

Skeletal muscle conditioning may be an effective rehabilitation intervention preceding functional electrical stimulation cycling

In our recent effort, we introduced a submaximal index that utilized ventilatory efficiency relative to CO2 production (VE/CO2) to evaluate the cardiovascular effectiveness to functional electrical stimulation lower-extremity cycling (FES-LEC) in persons with spinal cord injury (SCI) (Gorgey and Lawrence, 2016). When compared to the resting state, we found that an acute bout of FES-LEC resulted in increased ventilation during exercise and a significant decrease of approximately 22% in the VE/CO2 ratio, suggesting that this ratio could be utilized to monitor the cardiovascular response during submaximal FES-LEC in the SCI population. The study demonstrated that a potential limitation to the FES-LEC application is a heavy reliance on carbohydrate storage as a main source of substrate utilization. Reliance on carbohydrate utilization, transformation to fast-twitch fibers following SCI and random muscle recruitment are likely to introduce rapid muscle fatigue during FES-LEC applications. This may limit oxygen uptake and outcomes regarding cardiovascular profile. In this perspective, we propose that skeletal muscle conditioning via surface neuromuscular electrical stimulation (NMES) may be an essential rehabilitation intervention to improve the outcomes of FES-LEC applications.

Validation of Anthropometric Muscle Cross-Sectional Area Equation after Spinal Cord Injury

The purposes of this study were to cross-validate a previously derived anthropometric estimation equation specific to the spinal cord injury population and determine the ratios of absolute skeletal muscle cross-sectional area (CSA) for the quadriceps, hamstrings, and adductor muscle groups based on magnetic resonance imaging. The validation cohort consisted of eleven men with chronic (>1 yr. post injury) spinal cord injury (SCI). Ten individuals were classified as AIS A or B and one participant was classified as an AIS C. Significant correlations were found between the anthropometrically predicted CSAs and MRI-derived CSAs for the whole muscle including bone and intramuscular fat (r2=0.72, SEE=10.6 cm2, P<0.001), absolute muscle excluding bone and intramuscular fat (r2=0.60, SEE=10.1 cm2, P=0.005), and absolute quadriceps muscle (r2=0.67, SEE=5.5 cm2, P=0.002). The quadriceps, hamstrings and the adductor muscle groups represented 52±5%, 23±6%, and 20±4%, respectively, of the absolute muscle CSA. Our results suggest that the utilization of a previously developed anthropometric equation is applicable to a different validation cohort with SCI. The equation has the ability to predict whole muscle CSA, absolute muscle CSA excluding bone and intramuscular fat, and absolute muscle CSA of the quadriceps in individuals with chronic SCI.