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.
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.
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.
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.
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.
Sunghoon Shin, Robert W. Motl and Jacob J. Sosnoff
The rambling-trembling analysis of postural control maintains that the center of pressure (COP) trajectory can be decomposed into deviations resulting from supraspinal (i.e., rambling; RM) and spinal processes (i.e., trembling; TM). The purpose of this investigation was to test the rambling and trembling hypothesis by comparing persons with multiple sclerosis (MS) who had either elevated or normal spinal reflexes to healthy controls. 16 subjects with MS and 16 age and gender matched control subjects completed a postural control task. The persons with MS were divided into groups with high (MShigh) or low (MSlow) H-reflex amplitude. The MShigh group had an elevated ratio of TM to COP compared with healthy controls, but no differences in the ratio between RM and COP. The findings are congruent with the assumptions of the rambling-trembling hypothesis. Further work is needed to determine if RM and TM represent distinct spinal and supraspinal mechanisms to postural control.
David E. Conroy, Robert W. Motl and Evelyn G. Hall
Self-presentation has become an increasingly popular topic in exercise and sport psychology, yet few instruments exist to measure this construct. This paper describes two validation studies conducted on the Self-Presentation in Exercise Questionnaire (SPEQ), a paper-and-pencil instrument based on Leary and Kowalski’s (1990) two-component model of impression management. The SPEQ was designed to assess impression motivation (IM) and impression construction (IC) in exercise environments. The first study employed exploratory factor analysis to reduce a pool of 125 content-representative items to a subset of 41 items forming the hypothesized two-factor model of IM and IC. In the second study, the 41 items were further reduced using exploratory and confirmatory factor analyses in separate samples, and the reduced SPEQ also conformed to the IM and IC factor structure. The second study also provided initial evidence to support the convergent and discriminant validity of the SPEQ with theoretically salient constructs such as body surveillance, perceived physical ability, physical self-presentation confidence, social desirability, and social physique anxiety.
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.
Jian Xu, Poram Choi, Robert W. Motl and Stamatis Agiovlasitis
Physical activity (PA) and sedentary behavior may contribute to physical function in adults with intellectual disability (ID). This study examined whether objectively measured PA and sedentary behavior levels are associated with physical performance in adults with ID. Fifty-eight adults with ID (29 women and 29 men, age 44 ± 14 years) underwent a measurement of physical performance with the Short Physical Performance Battery (SPPB) and PA and sedentary time using a hip-worn accelerometer (wGT3X-BT; ActiGraph, Pensacola, FL). Moderate PA and age were significantly associated with the SPPB score (r = .39 and .34, respectively; p < .01). A hierarchical-regression model with moderate PA and age as independent variables indicated that moderate PA was a significant predictor of SPPB (p < .001; R 2 = .153), but age was not (p = .123; R 2 change = .036). Overall, moderate PA was significantly associated with the SPPB score, even after accounting for age, in adults with ID.