The consequences of multiple sclerosis (MS), particularly gait and walking dysfunction, may obfuscate (i.e., make unclear in meaning) the measurement of physical activity using body-worn motion sensors, notably accelerometers. This paper is based on an invited keynote lecture given at the 8th International Conference on Ambulatory Monitoring of Physical Activity and Movement, June 2022, and provides an overview of studies applying accelerometers for the measurement of physical activity behavior in MS. The overview includes initial research uncovering a conundrum with the interpretation of activity counts from accelerometers as a measure of physical activity. It then reviews research on calibration of accelerometer output based on its association with energy expenditure in yielding a biologically based metric for studying physical activity in MS. The paper concludes with other applications and lessons learned for guiding future research on physical activity measurement using accelerometry in MS and other populations with neurological diseases and conditions.
Measurement of Physical Activity Using Accelerometry in Persons With Multiple Sclerosis
Robert W. Motl
Chapter 2: Theoretical Models for Understanding Physical Activity Behavior among Children and Adolescents—Social Cognitive Theory and Self-Determination Theory
Robert W. Motl
Effect of Caffeine on Leg-Muscle Pain during Intense Cycling Exercise: Possible Role of Anxiety Sensitivity
Rachael C. Gliottoni and Robert W. Motl
This experiment examined the effect of a moderate dose of caffeine on perceptions of leg-muscle pain during a bout of high-intensity cycling exercise and the role of anxiety sensitivity in the hypoalgesic effect of caffeine on muscle pain during exercise. Sixteen college-age women ingested caffeine (5 mg/kg body weight) or a placebo and 1 hr later completed 30 min of cycling on an ergometer at 80% of peak aerobic capacity. The conditions were completed in a counterbalanced order, and perceptions of leg-muscle pain were recorded during the bouts of exercise. Caffeine resulted in a large reduction in leg-muscle pain-intensity ratings compared with placebo (d = −0.95), and the reduction in leg-muscle pain-intensity ratings was larger in those with lower anxiety-sensitivity scores than those with higher anxiety-sensitivity scores (d = −1.28 based on a difference in difference scores). The results support that caffeine ingestion has a large effect on reducing leg-muscle pain during high-intensity exercise, and the effect is moderated by anxiety sensitivity.
Step-Rate Thresholds for Physical Activity Intensity in Persons With Multiple Sclerosis
Stamatis Agiovlasitis and Robert W. Motl
This study examined whether the relationship between metabolic equivalent units (METs) and step-rate is altered in persons with multiple sclerosis (MS) and developed step-rate thresholds for activity intensity for these persons. Participants were 24 persons with MS (20 women; age = 44 ± 12) and 24 healthy persons without MS (20 women; age = 41 ± 11). The MS group was divided using the 12-item MS Walking Scale (MSWS-12) into two walking impairment subgroups: (a) minimal (n = 13, MSWS-12 ≤ 12.5) and (b) mild-moderate (n = 11, MSWS-12 > 12.5). METs were measured with spirometry and step-rate with hand-tally. Steprate, height, group, the step-rate by group interaction, and the square of step-rate significantly predicted METs. At a given height, the step-rate thresholds at 3 and 6 METs were lower for persons with minimal impairment than persons without MS and even lower for persons with mild-moderate impairment. The relationship between METs and step-rate is altered in persons with MS, lowering their step-rate thresholds for activity intensity, especially for persons with MS who have higher levels of walking impairment.
Sedentary Behavior in Persons With Multiple Sclerosis: Is the Time Ripe for Targeting a New Health Behavior?
Robert W. Motl and Rachel Bollaert
Sedentary behavior is prominent in persons with multiple sclerosis (MS) and may be associated with negative health consequences, yet our knowledge of sedentary behavior and its measurement, correlates, and consequences is in a stage of infancy—the focus on behavioral interventions might even be premature. This underscores the need for a research agenda focusing on sedentary behavior and its measurement, correlates, and consequences to inform the design of targeted interventions for persons with MS. Such research is important, as sedentary behavior represents a large opportunity for focal, theory-based behavioral interventions that could not only decrease sedentary behavior but also provide consequential life-changing benefits for persons with MS. The time is ripe for focal inquiry on sedentary behavior in MS and pursuing a new paradigm on health behavior change in this population.
Experimental Vertical Jump Model Used to Evaluate the Pivot Location in Klap Speed Skates
Todd L. Allinger and Robert W. Motl
This study used a vertical jump model to simulate the push-off phase for a skater using klap speed skates and evaluated die effects of pivot location and shoe base flexion on energy production. Boards of different lengths and one board with a hinge under the metatarsal heads were attached to the running shoes of volunteers. Six skaters performed 3 maximal effort vertical jumps across 5 different base conditions: running shoe, board that hinged under metatarsal heads, and rigid boards that pivoted with the ground al -25 mm (typical pivot location for klapskales), 0 mm, and +25 mm from the toes. There were no significant differences in total energy at take-off among the 3 rigid base conditions, but there were differences in potential and kinetic energy production. The total and kinetic energy produced at take-off was 9% greater in the hinged base condition than the corresponding rigid base condition. If differences in energy measures from the vertical jump reflect those for skating, a hinged boot base could increase skating speeds by about 3% over the current klap-skales, which have a rigid boot base.
Prediction of Energy Expenditure From Wrist Accelerometry in People With and Without Down Syndrome
Stamatis Agiovlasitis, Robert W. Motl, John T. Foley, and Bo Fernhall
This study examined the relationship between energy expenditure and wrist accelerometer output during walking in persons with and without Down syndrome (DS). Energy expenditure in metabolic equivalent units (METs) and activity-count rate were respectively measured with portable spirometry and a uniaxial wrist accelerometer in 17 persons with DS (age: 24.7 ± 6.9 years; 9 women) and 21 persons without DS (age: 26.3 ± 5.2 years; 12 women) during six over-ground walking trials. Combined groups regression showed that the relationship between METs and activity-count rate differed between groups (p < .001). Separate models for each group included activity-count rate and squared activity-count rate as significant predictors of METs (p ≤ .005). Prediction of METs appeared accurate based on Bland-Altman plots and the lack of between-group difference in mean absolute prediction error (DS: 17.07%; Non-DS: 18.74%). Although persons with DS show altered METs to activity-count rate relationship during walking, prediction of their energy expenditure from wrist accelerometry appears feasible.
Examining Multilevel Environmental Correlates of Physical Activity Among Older Adults With Multiple Sclerosis
Stephanie L. Silveira, Jessica F. Baird, and Robert W. Motl
Three hundred and sixty-three older adults with multiple sclerosis completed a cross-sectional study examining hierarchical correlates of physical activity using a social cognitive theory perspective within a social ecological model (i.e., built environment, social environment, and individual social cognitive theory variables). Hierarchical linear regression analyses were conducted, wherein significant associations were noted for built environment (i.e., land-use mix diversity and aesthetics) and physical activity in Step 1 (R 2 = .09). Social and built environment were significant correlates in Step 2 (R 2 = .15). Finally in Step 3, individual social cognitive theory variables (i.e., self-efficacy and outcome expectations) were the only significant correlates of total physical activity (R 2 = .38). Results were comparable for health-promoting physical activity; however, self-efficacy was the only significant correlate in Step 3 (R 2 = .36). This study provides guidance for researchers and practitioners on relevant targets for tailoring interventions for older adults with multiple sclerosis and supports an emphasis on self-efficacy as a primary predictor of health behavior change.
Physical Activity, Sedentary Behavior, and Physical Function in Older Adults With Multiple Sclerosis
Katie L. Cederberg, Robert W. Motl, and Edward McAuley
Older adults with multiple sclerosis (MS) experience the combined effects of aging and a chronic, disabling neurological disease on physical activity, sedentary behavior, and physical function. This study examined associations among light and moderate-to-vigorous physical activity (LPA and MVPA), sedentary behavior, and physical function in older adults with MS. Forty older adults with MS (median age = 60 years) who had a median Expanded Disability Status Scale score of 4.5 wore an accelerometer for a 7-day period and completed the Short Physical Performance Battery (SBBP), 6-minute walk (6MW), and timed 25-foot walk (T25FW). LPA was associated with SPPB (r s = .551, p < 0.01), 6MW (r s = .660, p < 0.01), and T25FW (r s = .623, p < 0.01) scores; MVPA was associated with 6MW (r s = .529, p < 0.01) and T25FW (r s = .403, p < 0.01) scores. There were significant associations between LPA, but not MVPA, with SPPB (β = .583, p < 0.01), 6MW (β = .613, p < 0.01), and T25FW (β = .627, p < 0.01) scores in linear regression analyses. Older adults with MS who engaged in more LPA demonstrated better physical function and therefore LPA might be a target of future behavioral interventions.
“How Come You Sent Me the Canadian One?” Application and Uptake of the Canadian Physical Activity Guidelines for Adults With Multiple Sclerosis in the United States
Whitney N. Neal, Emma Richardson, and Robert W. Motl
The uptake and benefits of the Canadian Physical Activity Guidelines for Adults with Multiple Sclerosis (PAGs) have been validated, but there is limited understanding regarding the knowledge, needs, and preferences of people with multiple sclerosis (MS) for implementing the PAGs outside of clinical research. The authors conducted online, semistructured interviews with 40 persons with MS from across the United States seeking information on awareness of and potential approaches for increasing the uptake of the PAGs. They identified first impressions and potential approaches for increasing the uptake of the PAGs through inductive, semantic thematic analysis. Participants perceived the PAGs as a good introduction for structured exercise but desired more information on how to meet the PAGs. Participants further believed that modifying the PAGs for inclusivity and applying a multifaceted approach for dissemination and implementation may increase uptake of exercise behavior. Physical activity research in MS should include both analyzing the effects of exercise and the unique challenges faced by persons with MS in putting the PAGs into practice.