Abstract-Historically, persons with paralysis have limited options for overground ambulation. Recently, powered exoskeletons, which are systems that translate the user's body movements to activate motors that move the lower limbs through a predetermined gait pattern, have become available. As part of an ongoing clinical study (NCT01454570), eight nonambulatory persons with paraplegia were trained to ambulate with a powered exoskeleton. Measurements of oxygen uptake (VO 2 ) and heart rate (HR) were recorded for 6 min each during each maneuver while sitting, standing, and walking. The average value of VO 2 during walking (11.2 +/-1.7 mL/kg/min) was significantly higher than for sitting and standing (3.5 +/-0.4 and 4.3 +/-0.9 mL/kg/min, respectively; p < 0.001). The HR response during walking was significantly greater than that of either sitting or standing (118 +/-21 vs 70 +/-10 and 81 +/-12 beats per minute, respectively; p < 0.001). Persons with paraplegia were able to ambulate efficiently using the powered exoskeleton for overground ambulation, providing the potential for functional gain and improved fitness.Clinical Trial Registration: ClinicalTrials.gov; NCT01454570; "The ReWalk Exoskeletal Walking System for Persons with Paraplegia (VA_ReWalk)"; https://clinicaltrials.gov/ct2/show/ NCT01454570
Multiple sclerosis leads to prominent hippocampal atrophy, which is linked to memory deficits. Indeed, 50% of multiple sclerosis patients suffer memory impairment, with negative consequences for quality of life. There are currently no effective memory treatments for multiple sclerosis either pharmacological or behavioral. Aerobic exercise improves memory and promotes hippocampal neurogenesis in nonhuman animals. Here, we investigate the benefits of aerobic exercise in memory-impaired multiple sclerosis patients. Pilot data were collected from two ambulatory, memory-impaired multiple sclerosis participants randomized to non-aerobic (stretching) and aerobic (stationary cycling) conditions. The following baseline/follow-up measurements were taken: high-resolution MRI (neuroanatomical volumes), fMRI (functional connectivity), and memory assessment. Intervention was 30-minute sessions 3 times per week for 3 months. Aerobic exercise resulted in 16.5% increase in hippocampal volume and 53.7% increase in memory, as well as increased hippocampal resting-state functional connectivity. Improvements were specific, with no comparable changes in overall cerebral gray matter (+2.4%), non-hippocampal deep gray matter structures (thalamus, caudate: -4.0%), or in non-memory cognitive functioning (executive functions, processing speed, working memory: changes ranged from -11% to +4%). Non-aerobic exercise resulted in relatively no change in hippocampal volume (2.8%) or memory (0.0%), and no changes in hippocampal functional connectivity. This is the first evidence for aerobic exercise to increase hippocampal volume and connectivity and improve memory in multiple sclerosis. Aerobic exercise represents a cost-effective, widely available, natural, and self-administered treatment with no adverse side effects that may be the first effective memory treatment for multiple sclerosis patients.
Men with spinal cord injury are at an increased risk for secondary medical conditions, including metabolic disorders, accelerated musculoskeletal atrophy, and, for some, hypogonadism, a deficiency, which may further adversely affect metabolism and body composition. A prospective, open label, controlled drug intervention trial was performed to determine whether 12 months of testosterone replacement therapy increases lean tissue mass and resting energy expenditure in hypogonadal males with spinal cord injury. Healthy eugonadal (n = 11) and hypogonadal (n = 11) outpatients with chronic spinal cord injury were enrolled. Hypogonadal subjects received transdermal testosterone (5 or 10 mg) daily for 12 months. Measurements of body composition and resting energy expenditure were obtained at baseline and 12 months. The testosterone replacement therapy group increased lean tissue mass for total body (49.6 ± 7.6 vs. 53.1 ± 6.9 kg; p < 0.0005), trunk (24.1 ± 4.1 vs. 25.8 ± 3.8 kg; p < 0.005), leg (14.5 ± 2.7 vs. 15.8 ±2.6 kg; p = 0.005), and arm (7.6 ± 2.3 vs. 8.0 ± 2.2 kg; p < 0.005) from baseline to month 12. After testosterone replacement therapy, resting energy expenditure (1328 ± 262 vs. 1440 ± 262 kcal/d; p < 0.01) and percent predicted basal energy expenditure (73 ± 9 vs. 79 ± 10%; p < 0.05) were significantly increased. In conclusion, testosterone replacement therapy significantly improved lean tissue mass and energy expenditure in hypogonadal men with spinal cord injury, findings that would be expected to influence the practice of clinical care, if confirmed. Larger, randomized, controlled clinical trials should be performed to confirm and extend our preliminary findings.
Background: Fluctuations in 24-hour cardiovascular hemodynamics, specifically heart rate (HR) and blood pressure (BP), are thought to reflect autonomic nervous system (ANS) activity. Persons with spinal cord injury (SCI) represent a model of ANS dysfunction, which may affect 24-hour hemodynamics and predispose these individuals to increased cardiovascular disease risk. Objective: To determine 24-hour cardiovascular and ANS function among individuals with tetraplegia (n = 20; TETRA: C4-C8), high paraplegia (n = 10; HP: T2-T5), low paraplegia (n = 9; LP: T7-T12), and non-SCI controls (n = 10). Twenty-four-hour ANS function was assessed by time domain parameters of heart rate variability (HRV); the standard deviation of the 5-minute average R-R intervals (SDANN; milliseconds/ms), and the root-mean square of the standard deviation of the R-R intervals (rMSSD; ms). Subjects wore 24-hour ambulatory monitors to record HR, HRV, and BP. Mixed analysis of variance (ANOVA) revealed significantly lower 24-hour BP in the tetraplegic group; however, BP did not differ between the HP, LP, and control groups. Mixed ANOVA suggested significantly elevated 24-hour HR in the HP and LP groups compared to the TETRA and control groups (P < 0.05); daytime HR was higher in both paraplegic groups compared to the TETRA and control groups (P < 0.01) and nighttime HR was significantly elevated in the LP group compared to the TETRA and control groups (P < 0.01). Twenty-four-hour SDANN was significantly increased in the HP group compared to the LP and TETRA groups (P < 0.05) and rMSSD was significantly lower in the LP compared to the other three groups (P < 0.05). Elevated 24-hour HR in persons with paraplegia, in concert with altered HRV dynamics, may impart significant adverse cardiovascular consequences, which are currently unappreciated.
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