Heart rate variability is reduced in COVID-19 survivors and associated with physical activity and fatigue

Reduced heart rate variability (HRV) and fatigue are common after COVID-19 infection and both are potentially influenced by physical activity (PA). We compared resting HRV, PA from accelerometers and questionnaires, and self-reported fatigue in 41 COVID-19 survivors (~8 months postinfection, 38 ± 17 years) with 41 matched controls. Differences in HRV were observed on acceleration capacity (p = 0.041), deceleration capacity (p = 0.032), high-frequency peak frequency (p = 0.019), absolute low-frequency power (p = 0.042), relative very low-frequency power (p = 0.012), SD2 (from Poincare plot; p = 0.047), and DFA2 (slope of long-term detrended fluctuation analysis; p = 0.004). Fatigue was greater in COVID-19 survivors (p < 0.001) with no differences in PA. Moderate-vigorous physical activity (MVPA) (Standardized Beta = -0.427, p = 0.003) and steps per day (Standardized Beta = -0.402, p = 0.007) were associated with DFA2 in COVID-19 survivors after controlling for age, sex, and body fat percentage. Fatigue was correlated to less MVPA (Spearman's rho = 0.342, p = 0.031) and fewer steps per day (rho = 0.329, p = 0.038) in COVID-19 survivors, and was indirectly linked to HRV through these PA mediators (Estimate = -0.20; p = 0.040). We present a model showing the complex relations between HRV, PA, and fatigue that provides the foundation for strategies to improve outcomes and rehabilitation after COVID-19 infection.

Home-based exercise improves subclinical atherosclerosis marker in multiple sclerosis

PURPOSE

Using a 12-week, randomized controlled trial coupled with social cognitive theory behavioral coaching, we aimed to assess the effect of a home-based aerobic training intervention versus an attention-control on aerobic fitness, subclinical atherosclerosis, and mobility in persons with MS.

METHODS

Persons with MS with an expanded disability status scale score between 0 and 4 were randomized to a 12-week aerobic exercise (EX) (n = 26; 19 females; 49 yrs; 28.8 kg/m2) or attention-control (CON) condition (stretching; n = 22; 16 females; 44 yrs; 29.2 kg/m2). Aerobic capacity was assessed via a graded cycle ergometry test with indirect calorimetry. The co-primary measures of subclinical atherosclerosis assessed included carotid intima media thickness, a test of vasodilatory reactivity, and arterial stiffness. Mobility was assessed via a timed 25-foot walk test (T25FW) and a 6 min walk test. The EX group engaged in cycle ergometry 3d/wk with gradual increases in the intensity and duration of the exercise sessions. CON participated in standardized stretching designed to provide the same contact time as EX 3d/wk. Behavioral coaching took place via weekly phone/video chats to track adherence.

RESULTS

Aerobic capacity, vasodilatory reactivity, and T25FW speed increased only in the EX group, 7%, 16%, and 13% (p<0.05), respectively; whereas the CON group did not change.

CONCLUSION

The EX group had modest, yet significant, increases in aerobic capacity over the 12-week period, coupled with improvements in T25FW speed and vasodilatory reactivity. A home-based exercise intervention can improve outcomes of a subclinical marker of atherosclerosis, which provides a basis for examining these outcomes in persons prescreened for CVD-related comorbidities and/or mobility issues.

Randomized controlled trial of the behavioral intervention for physical activity in multiple sclerosis project: Social cognitive theory variables as mediators

BACKGROUND

We recently reported in a phase-III, randomized controlled trial that a behavioral intervention based on social cognitive theory (SCT) and delivered through the Internet using e-learning approaches increased device-measured minutes/day of moderate-to-vigorous physical activity (MVPA) over a 6-month period among persons with multiple sclerosis (MS).

OBJECTIVE

This planned tertiary outcome paper examined SCT variables as mediators of the behavioral intervention effect on change in device-measured minutes/day of MVPA.

METHOD

Persons with MS (N = 318) were randomized into behavioral intervention (n = 159) or attention/social contact control (n = 159) conditions. The conditions were administered over a 6-month period via an Internet website and supported with behavioral coaching by persons who were uninvolved in screening, recruitment, random assignment, and outcome assessments. We collected MVPA and SCT data before and after the 6-month period. The data analysis involved linear mixed modeling on MVPA and SCT outcomes followed by latent change score modeling for examining SCT variables as mediators of the intervention effect on change in MVPA.

RESULTS

The linear mixed model indicated statistically significant group by time interactions on device-measured minutes/day of MVPA and scores from SCT measures of exercise self-efficacy, barriers self-efficacy, goal setting, and planning. The effect of the intervention on device-measured minutes/day of MVPA was mediated by the SCT variable of exercise self-efficacy based on the statistical significance of the Wald z-score for the indirect effect in the latent change score model.

CONCLUSIONS

This study provides evidence for exercise self-efficacy as a SCT mediator of the behavioral intervention effect on device-measured minutes/day of MVPA in persons with MS.

Physical function across the lifespan in adults with multiple sclerosis: An application of the Short Physical Performance Battery

BACKGROUND

Multiple sclerosis (MS) typically has its onset in early and middle adulthood, but the population is steadily becoming more dominated by older adults. One of the primary consequences of both MS and aging involves declines of lower extremity physical function and mobility. This cross-sectional study compared physical function status based on Short Physical Performance Battery (SPPB) summary and component scores between persons with MS and healthy controls across 6 age groups. We further examined associations between SPPB summary scores and component scores as well as associations between summary scores and measures of physical and cognitive function for identifying the strongest correlates of SPPB summary scores.

METHODS

The study involved secondary analysis of cross-sectional data from multiple studies. Ambulatory adults with MS who were relapse-free for the last 30 days were recruited, and controls were recruited based on similar criteria to adults with MS except without the diagnosis of MS or relapses. The sample of 345 persons with MS and 174 controls completed questionnaires regarding demographic and clinical information and underwent assessments of physical and cognitive function including the SPPB, 6-Minute Walk, Timed 25-Foot Walk, Symbol Digit Modalities Test, California Verbal Learning Test-Second Edition, and Brief Visuospatial Memory Test-Revised.

RESULTS

The two-way ANOVA indicated a main effect of MS status (F(5,500)=34.74, p<.01, η²=0.065), a main effect of age (F(1,500)=3.88, p<.01, η²=0.037), and no MS status by age interaction (F(5,500)=1.20, p=.31, η²=0.012) on SPPB scores. The bivariate correlation analysis indicated that summary SPPB scores were associated with component SPPB scores in the overall samples of persons with MS (r_s=0.71 to 0.83) and controls (r_s=0.42 to 0.91) as well as within most age groups of MS (r_s=0.63 to 0.91) and controls (r_s=0.34 to 1.00). The associations between SPPB scores and physical function outcomes were larger in the sample of persons with MS (r_s=-0.72 to 0.76) than controls (r_s=-0.47 to 0.48). SPPB scores were further significantly associated with scores on cognitive outcomes in persons with MS (r_s=0.31 to 0.43), whereas these associations were weaker in controls (r_s=0.09 to 0.32). Overall, the associations between SPPB scores and physical function outcomes were stronger than the associations between SPPB scores and cognitive function outcomes.

CONCLUSION

Overall, MS status and aging have additive effects on physical function, and the summary SPPB score may be driven by a specific component within each age group. SPPB scores may be driven more by mobility rather than cognition, and are consistent with cognitive-motor coupling in MS. The novelty of this study provides evidence of worsening physical function based on the application of the SPPB and its scores across the lifespan in persons with MS and controls, and this has important implications particularly given the increasing prevalence of older adults with MS.

Primary results of a phase-III, randomized controlled trial of the Behavioral Intervention for increasing Physical Activity in Multiple Sclerosis project

BACKGROUND

We undertook a phase-III, randomized controlled trial (RCT) that examined the effectiveness of a behavioral intervention based on social cognitive theory (SCT) and delivered through the Internet using e-learning approaches for immediate and sustained increases in physical activity among persons with multiple sclerosis (MS).

METHOD

The study followed a parallel group RCT design. Persons with MS (N = 318) were randomized into either behavioral intervention (n = 159) or attention/social contact control (n = 159) conditions. The conditions were administered over a 6-month period by persons who were uninvolved in screening, recruitment, random assignment, and outcome assessment. There was a 6-month follow-up period without access of conditions. We collected outcome data every 6 months over the 12-month period. The primary outcome was device-measured minutes/day of moderate-to-vigorous physical activity (MVPA). The data analysis involved a modified intent-to-treat approach (i.e. those who received the allocated conditions) using a linear mixed model.

RESULTS

There was a significant group by time interaction on the primary outcome of device-measured minutes/day of MVPA (p < 0.005). MVPA was increased immediately after the 6-month period in the behavioral intervention compared with control, and this difference was sustained over the 6-month follow-up.

CONCLUSION

This study provides evidence for the effectiveness of a widely scalable approach for increasing MVPA in persons with MS.

Moderate-to-Vigorous Physical Activity is Related With Retinal Neuronal and Axonal Integrity in Persons With Multiple Sclerosis

BACKGROUND

Moderate-to-vigorous physical activity (MVPA) may confer benefits for axonal and/or neuronal integrity in adults with multiple sclerosis (MS).

PURPOSE

Examine the association between device-measured MVPA with optical coherence tomography (OCT) metrics of retinal nerve fiber layer (RNFL) thickness and total macular volume (TMV) in persons with and without MS.

METHODS

Adults with MS (N = 41), along with sex-matched healthy control (HC) participants (N = 79), underwent measurements of retinal morphology via OCT and wore an accelerometer for a period of 7 days as a measure of MVPA.

RESULTS

Persons with MS had significantly lower MVPA, RNFL thickness, and TMV compared with HCs. MVPA was correlated with RNFL (r = .38, P < .01) thickness and TMV (r = .49, P < .01). Hierarchical linear regression analyses indicated that addition of MVPA attenuated the Group effect on RNFL and TMV. MVPA accounted for 8% and 3% of the variance in TMV (β = .343, P < .01) and RNFL thickness (β = .217, P = .03), respectively.

CONCLUSION

MVPA was positively associated with axonal and neuronal integrity assessed by OCT and partially explained group differences in those metrics. These results present possible future targets for MS management by increasing MVPA.

Self-efficacy and Physical and Cognitive Function in Older Adults with Multiple Sclerosis

Background

There is evidence of a demographic shift in the prevalence of multiple sclerosis (MS) such that it is now common in older adults. Older adults with MS undergo declines in function, and aging with MS may compromise one's perception of confidence for managing this disease and its manifestations. This cross-sectional study examined the associations between self-efficacy and physical and cognitive function in older (≥ 60 years) adults with MS.

Methods

The sample included 40 older adults with MS who completed the Multiple Sclerosis Self-efficacy (MSSE) Scale, undertook measures of physical and cognitive function, and wore an accelerometer for 7 days. The data were analyzed using partial Spearman correlations and linear regression.

Results

Correlation analyses indicated that function, but not control, subscale scores on the MSSE Scale correlated with all measures of physical, but not cognitive, function. Linear regression analyses indicated that the function subscale of the MSSE Scale was the only variable that consistently explained variance in physical function outcomes.

Conclusions

The findings are novel evidence of the association between self-efficacy for function and physical function outcomes in older adults with MS. Future research on self-efficacy is warranted with the goal of improving physical function in older adults with MS.

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.

Physiological response to firefighting activities of various work cycles using extended duration and prototype SCBA

Firefighters' self-contained breathing apparatus (SCBA) protects the respiratory system during firefighting but increases the physiological burden. Extended duration SCBA (>30 min) have increased air supply, potentially increasing the duration of firefighting work cycles. To examine the effects of SCBA configuration and work cycle (length and rest), 30 firefighters completed seven trials using different SCBA and one or two bouts of simulated firefighting following work cycles common in the United States. Heart rate, core temperature, oxygen consumption, work output and self-reported perceptions were recorded during all activities. Varying SCBA resulted in few differences in these parameters. However, during a second bout, work output significantly declined while heart rates and core temperatures were elevated relative to a single bout. Thirty seven per cent of the subjects were unable to complete the second bout in at least one of the two-bout conditions. These firefighters had lower fitness and higher body mass than those who completed all assigned tasks. Practitioner Summary: The effects of extended duration SCBA and work/rest cycles on physiological parameters and work output have not been examined. Cylinder size had minimal effects, but extended work cycles with no rest resulted in increased physiological strain and decreased work output. This effect was more pronounced in firefighters with lower fitness.

The Virtual Short Physical Performance Battery: Psychometric Properties and Validation in Older Adults With Multiple Sclerosis

Background: There are increasing numbers of older adults with multiple sclerosis (MS) who undergo declines in physical function that require attention of clinicians and researchers. Objective and perceived measures of disablement feasible for clinical and residential settings, such as the Short Physical Performance Battery and its virtual counterpart (vSPPB), are critical for defining the degree of disablement. Objective: We evaluated the psychometric properties and validity of the vSPPB as a measure of perceived lower extremity physical function in older adults with MS (age ≥60 years). Method: The sample included 35 older adults with MS and 35 age- and sex-matched healthy controls (age ≥60 years) who completed a battery of assessments, including the vSPPB. Results: The vSPPB performed satisfactorily in older adults with MS regarding data quality, scaling assumptions, and acceptability (i.e., psychometrics). The vSPPB further demonstrated criterion, known-groups, convergent, and discriminant construct validity. Conclusion: This report provides evidence for the validity of vSPPB scores as a measure of perceived lower extremity physical function in older adults with MS.