Validation of the Godin Leisure-Time Exercise Questionnaire Classification Coding System Using Accelerometry in Multiple Sclerosis

Objective: There have been recent efforts toward creating a health contribution score (HCS) from the Godin Leisure-Time Exercise Questionnaire (GLTEQ) that reflects public-health guidelines for levels of moderate-to-vigorous physical activity (MVPA). The HCS yields categories of insufficiently active (less substantial or low benefits), moderately active (some benefits), and active (substantial benefits). The present study examined the validity of the GLTEQ HCS and its categories as reflecting levels of MVPA in multiple sclerosis (MS). Method: The sample included 684 persons with MS. Participants wore an accelerometer on an elastic belt around the waist above the nondominant hip during the waking hours of the day over a 7-day period and completed the GLTEQ. Results: The data analyses supported a large correlation between the GLTEQ HCS and accelerometer-measured MVPA, r = .46, p \u3c .0001, but small correlations with accelerometer-measured light physical activity (LPA), r = .16, p \u3c .001 and sedentary time, r = −.13, p = .001. There further was a large difference in accelerometer-measured MVPA between categories of physical activity levels (i.e., insufficiently active vs. active) based on the GLTEQ HCS (d = 0.89), but small differences in LPA (d = 0.39) and sedentary time (d = −0.31). Those results were unchanged in additional data analyses accounting for LPA and sedentary behavior. Conclusions: The GLTEQ HCS and categories primarily reflect MVPA rather than LPA and sedentary behavior in persons with MS

Fitness and cognitive processing speed in persons with multiple sclerosis

Background: Cognitive impairment is prevalent, disabling, and poorly managed in persons with MS. To date, two studies have identified aerobic capacity as a correlate of cognition in MS, but there has yet to be an investigation of multiple domains of fitness as correlates of cognition in this population. Such an examination is important for identifying the appropriate modes of exercise training for possibly improving cognition. Objective: This study examined the relationships among aerobic capacity, muscle strength, and balance with cognitive function in persons with MS. Methods: 31 persons with MS and 31 controls matched by age, height, weight, and sex completed two neuropsychological measures of cognitive processing speed (PASAT and SDMT). Participants underwent an incremental exercise test to exhaustion on a cycle ergometer as a measure of aerobic capacity; three maximal isometric extensions and one maximal isometric flexion with each knee on an isokinetic dynamometer at three different joint angles as a measure of muscular strength; and stood on a force platform without shoes for 30 seconds with eyes open to measure postural sway. Results: Independent samples t-tests indicated that MS and control groups differed in PASAT score (t = −2.13, p = .04), SDMT score (t = −2.69, p = .01), aerobic capacity (t = −2.99, p < .01), and balance (t = 4.06, p < .01), but not in muscular strength. Cognitive processing speed was significantly associated with aerobic capacity (r = .43 and .44) and balance (r= −.52 and −.52), but not muscular strength in the overall and MS samples, respectively. Lastly, hierarchical regression analysis indicated that aerobic capacity (β = .27) and balance (β = −.40) accounted for differences in cognitive processing speed between MS and control groups. Conclusions: Aerobic capacity and balance, but not muscular strength, are associated with cognitive processing speed in persons with MS, suggesting that aerobic exercise and balance training are avenues for possibly improving cognitive impairment in this population

The acute effects of varying intensities of treadmill walking exercise on cognition in persons with multiple sclerosis

Background: Exercise training represents a promising approach for managing cognitive impairment in persons with multiple sclerosis (MS). There is preliminary evidence that treadmill walking exercise might be the modality of exercise that exerts the greatest beneficial effects on executive control in persons with mild MS disability. However, the dose-dependent effects of varying intensities of treadmill walking exercise on this cognitive function are unknown. Such an investigation is critical for providing the final data for delineating the optimal exercise stimulus (or stimuli) for improving executive control in persons with MS. Objectives: The present study compared the acute effects of light, moderate, and vigorous intensity treadmill walking exercise on multiple aspects of executive control (i.e., interference control and response inhibition) relative to quiet rest in 24 persons with mild MS disability, using a within-subjects, repeated-measures experimental design. Methods: Participants completed four experimental conditions that consisted of 20 minutes of light intensity treadmill walking exercise, moderate intensity treadmill walking exercise, vigorous intensity treadmill walking exercise, and quiet rest in a randomized, counterbalanced order. Participants underwent a modified-flanker task and Go/No-Go task as measures of executive control immediately prior to and following each condition. Results: Repeated-measures ANOVAs indicated large, statistically significant pre-to-post reductions in the cost of interfering stimuli on reaction time, but not accuracy, on the modified-flanker task for light, moderate, and vigorous intensity exercise compared with quiet rest (F(3,69)=4.27,p=.01,ηp2=.16) that were similar in magnitude. There further were no overall effects of exercise intensities on percent accuracy from the Go/No-Go task (F(3,69)=0.33,p=.81,ηp2=.01), compared with quiet rest. Conclusions: The present results support light, moderate, and vigorous intensity treadmill walking as exercise stimuli that might particularly benefit speed-related aspects of executive control (i.e., interference control of reaction time). This represents the final step in delineating the optimal exercise stimuli for inclusion in a subsequent longitudinal exercise training intervention for improving this cognitive function in persons with mild MS disability

Falls and Physical Activity in Persons with Multiple Sclerosis

Objectives. To examine the association between fall history and physical activity using an objective measure of physical activity (i.e., accelerometry) in persons with multiple sclerosis. Design. A community-based sample of 75 ambulatory persons with multiple sclerosis volunteered for the investigation. Participants self-reported fall history in the last year, underwent a neurological exam to determine Expanded Disability Status Scale (EDSS) score, and wore an accelerometer around the waist for 7 consecutive days to determine physical activity. Results. Overall, 37 persons (49.3% of the sample) reported falling in the last year with 28 of the 37 falling more than once. Persons who fell in the last year had a significantly lower number of steps/day than nonfallers (3510 versus 4940 steps/day; P \u3c .05). However, when controlling for disability status there was no statistically significant difference between fallers and nonfallers (4092 versus 4373 steps/day; P \u3e.05). Conclusions. Collectively, the findings suggest that fall history may have little impact on current physical activity levels in persons with multiple sclerosis

Phase-III, Randomized Controlled Trial of the Behavioral Intervention for Increasing Physical Activity in Multiple Sclerosis: Project BIPAMS

Background We propose a phase-III, randomized controlled trial (RCT) that examines the effectiveness of a behavioral intervention based on social cognitive theory (SCT) and delivered through the Internet using e-learning approaches for increasing physical activity and secondary outcomes (e.g., symptoms) in a large sample of people with multiple sclerosis (MS) residing throughout the United States. Methods/design The proposed phase-III trial will use a parallel group, RCT design that examines the effect of a 6-month behavioral intervention for increasing physical activity and secondarily improving mobility, cognition, symptoms, and quality of life (QOL) in persons with MS. The primary outcome is accelerometer-measured moderate-to-vigorous physical activity (MVPA). The secondary outcomes include self-report measures of physical activity, walking impairment, cognition, fatigue, depression, anxiety, pain, sleep quality, and QOL. The tertiary outcomes are mediator variables based on SCT. Participants (N = 280) will be randomized into behavioral intervention (n = 140) or attention and social contact control (n = 140) conditions using computerized random numbers with concealed allocation. The conditions will be administered over 6-months by persons who are uninvolved in screening, recruitment, random assignment, and outcome assessment. There will be a 6-month follow-up without intervention access/content. We will collect primary, secondary, and tertiary outcome data every 6 months over the 12-month period. Data analysis will involve intent-to-treat principles and latent growth modeling (LGM). Discussion The proposed research will provide evidence for the effectiveness of a novel, widely scalable approach for increasing lifestyle physical activity and improving secondary outcomes and QOL in persons with MS

Investigating domain-specific cognitive impairment among patients with multiple sclerosis using touchscreen cognitive testing in routine clinical care

Cognitive dysfunction is present in up to 70% of patients with multiple sclerosis (MS) and has been reported at all stages and in all subtypes of the disease. These deficits have been reported across a variety of cognitive domains, but are generally under-recognized and incompletely evaluated in routine clinical practice. The aim of this study was to investigate the spectrum of cognitive impairment in patients with MS presenting to a specialist MS clinic using the Cambridge Neuropsychological Test Automated Battery (CANTAB), administered on a touchscreen platform. Ninety MS patients completed computerized CANTAB tasks assessing working memory, executive function, processing speed, attention, and episodic memory. Scores were adjusted for age, sex, and level of education and classified as normal or impaired based on comparison with a large normative data pool. We also investigated the impact of clinical and demographic variables which could potentially influence cognitive performance including patient educational level (a proxy for cognitive reserve), disease status (duration, course, and severity of MS), and depression. CANTAB testing detected cognitive impairment in 40 patients (44% of the sample). The most frequently impaired domain was executive function, present in 55% of cognitively impaired individuals. Disease duration and severity were significantly associated with performance across various cognitive domains. Patients with depressive symptoms were also more likely to exhibit impaired processing speed. Results from this study confirm that cognitive impairment is common and occurs across a range of domains among MS patients attending routine clinical visits. CANTAB tasks provide a sensitive and practical approach to cognitive testing in MS patients as part of a holistic patient assessment

Clinical Study Oxygen Cost of Walking in Persons with Multiple Sclerosis: Disability Matters, but Why?

Background. The oxygen cost (O 2 cost) of walking is elevated in persons with MS, particularly as a function of increasing disability status. Objective. The current study examined symptomatic (i.e., fatigue, pain, anxiety, and depression) and gait (i.e., velocity, cadence, and step length) variables that might explain why disability status is associated with O 2 cost of walking in persons with MS. Materials and Methods. 82 participants completed the Patient-Determined Disease Steps, Fatigue Severity Scale, McGill Pain Questionnaire, and Hospital Anxiety and Depression Scale and undertook 2 trials of walking on a GAITRite electronic walkway. Participants then completed a six-minute walk test with concurrent assessment of expired gases for quantifying oxygen consumption and O 2 cost of walking. Results. Disability ( = 0.55) as well as fatigue ( = 0.22), gait velocity ( = −0.62), cadence ( = −0.73), and step length ( = −0.53) were associated with the O 2 cost of walking. Cadence ( = −0.67), but not step length ( = −0.14) or fatigue ( = −0.10), explained the association between disability and the O 2 cost of walking. Conclusions. These results highlight cadence as a target of rehabilitation for increasing metabolic efficiency during walking among those with MS, particularly as a function of worsening disability

Vertical cavity lasers for optical interconnects

Vertical-cavity surface-emitting lasers are generating much interest due to their geometric suitability for two-dimensional array fabrication and their potential for achieving ultra-low thresholds. Here we report on optically- and electrically-pumped microlaser devices. having transverse dimensions of a few microns and active material lengths of a few hundred A. The very small volumes are a key factor in achieving low thresholds. So far however surface recombination has prevented us from achieving thresholds much below 1 mA