Biomedical subjects

Robert W Motl

Publications and source records attributed to Robert W Motl.

At least 19 recordsLinked to original sources

PubMed2006

Cardiorespiratory fitness: A predictor of cortical plasticity in multiple sclerosis.

Deficits in cognitive abilities are commonly observed among individuals with multiple sclerosis (MS). Recent neuroimaging studies have provided evidence for the existence of cortical plasticity in MS, with cognitively impaired participants recruiting additional brain areas to perform challenging tasks. The existence of altered cerebral activations in MS provides hope for the utilization of neural resources to reduce cognitive deficits that challenge everyday living in MS by employing alternative interventions such as cognitive and fitness training. In this study, we examined whether higher physical fitness levels enhance cognitive and neural plasticity in MS patients. The present study is the first to investigate the impact of cardiorespiratory fitness on cerebrovascular functioning of MS patients. 24 participants with relapsing-remitting MS were recruited for the study. All participants went through a fitness assessment and were scanned in a 3 T MRI system during the Paced Visual Serial Addition Test (PVSAT). Higher fitness levels were associated with faster behavioral performance and greater recruitment of right IFG/MFG, a region of the cerebral cortex recruited by MS patients during performance of PVSAT to purportedly compensate for the cognitive deterioration attributable to MS. In contrast, lower levels of fitness were associated with enhanced ACC activity, suggestive of the presence of greater interference and the potential for error in lower fit MS participants. These results are promising, suggesting the need for further investigation of the utility of aerobic fitness training as a possible method to support the development of additional cortical resources in an attempt to counter the cognitive decline resulting from MS.

Adult↗

PubMed2006

Validity of physical activity measures in ambulatory individuals with multiple sclerosis.

PURPOSE: The literature suggests that individuals with multiple sclerosis (MS) engage in less physical activity than non-diseased individuals. That conclusion, however, depends upon the validity of scores from measures of physical activity among the MS population. This study evaluated the validity of scores from two self-report surveys, a pedometer, and an accelerometer and during seven days of free-living conditions among individuals with MS. METHOD: Participants were 30 individuals (28 females, two males) with an established definite diagnosis of MS. The participants wore a pedometer and a single-axis accelerometer during the waking hours of a 7-day period. After the 7-day period, participants returned to the lab and completed a self-administered physical activity questionnaire and then underwent a 7-day physical activity recall. RESULTS: There were strong correlations (a) between scores from the two self-report measures of physical activity and (b) between scores from the two objective measures of physical activity, and (c) weaker, but moderate-to-strong correlations between scores from the self-report and objective measures of physical activity. CONCLUSION: Our results support the quantification of physical activity among those with MS using validated self-report and objective measures.

Adult↗

PubMed2006

Effect of acute leg cycling on the soleus H-reflex and modified Ashworth scale scores in individuals with multiple sclerosis.

This study examined the effect of a single bout of unloaded leg cycling on the soleus H-reflex and modified Ashworth scale (MAS) in 27 individuals with multiple sclerosis (MS) who had spasticity of the leg muscles, but were not currently taking anti-spastic medications. The soleus H-reflex and MAS data were collected before and 10, 30, and 60 min after 20 min of unloaded leg cycling and a control condition. The acute bout of unloaded leg cycling resulted in concomitant and prolonged reductions in the soleus H-reflex and MAS scores compared with the control condition. This provides converging evidence for the anti-spastic potential of acute unloaded leg cycling in individuals with MS.

Adult↗

PubMed2006

Perceptions of physical and social environment variables and self-efficacy as correlates of self-reported physical activity among adolescent girls.

OBJECTIVE: This cross-sectional study examined the direct and indirect effects of perceived equipment accessibility, neighborhood safety, and social support on self-reported physical activity among older adolescent girls. METHODS: Adolescent girls (n = 1,655) who were in the 12th grade completed a battery of questionnaires that included self-report measures of the perceived physical environment, social support, barriers self-efficacy, and physical activity. RESULTS: Perceived neighborhood safety did not exhibit direct or indirect effects on self-reported physical activity. Perceived equipment accessibility exhibited an indirect effect on self-reported physical activity that was accounted for by barriers self-efficacy. Perceived social support exhibited direct and indirect effects on self-reported physical activity; the indirect effect was accounted for by barriers self-efficacy. The relationships were independent of parental education and body mass index (BMI). CONCLUSIONS: Perceived physical environmental factors indirectly influenced self-reported physical activity, and perceived social environmental factors both directly and indirectly influenced self-reported physical activity in this sample of older adolescent girls.

Adolescent↗

PubMed2006

Symptoms, self-efficacy, and physical activity among individuals with multiple sclerosis.

Using social-cognitive theory, we examined the associations among symptoms, self-efficacy, and physical activity in 196 individuals with multiple sclerosis (MS). Participants completed symptoms, self-efficacy, and physical activity measures and wore an accelerometer for 7 days. There was a moderate inverse correlation between symptoms and physical activity (varphi = -.42). Subsequent analyses indicated that symptoms had direct negative relationships with self-efficacy (gamma = -.32) and physical activity (gamma = -.24), and self-efficacy had a direct positive relationship with physical activity (beta = .57). This study provides initial support for symptoms as a correlate of physical activity in individuals with MS. Monitoring symptoms during a physical activity program and altering the exercise prescription during symptom exacerbation might be a method for increasing exercise adherence.

Activities of Daily Living↗

PubMed2006

Does self-efficacy influence leg muscle pain during cycling exercise?

UNLABELLED: This experiment examined the effect of a manipulation of self-efficacy beliefs on perceptions of leg muscle pain during moderate-intensity cycling exercise among women. Low to moderately active college-age women (n = 28) were randomly assigned to 1 of 2 conditions that were designed to either increase or decrease efficacy beliefs for engaging in moderate intensity physical activity. Efficacy was manipulated based on bogus feedback after a maximal incremental exercise test. Within 2-3 days after the efficacy manipulation, participants completed 30 min of cycling on an ergometer at 60% peak oxygen consumption. Perceptions of leg muscle pain, as well as work rate and oxygen consumption, were recorded during exercise. There was an initial relationship between baseline self-efficacy and pain ratings during a maximal incremental exercise test. Although the provision of bogus feedback was effective for manipulating self-efficacy, there was no differential effect on leg muscle pain intensity ratings during the 30 min bout of moderate-intensity cycling. The results imply that our manipulation of self-efficacy for prolonged exercise does not influence leg muscle pain during moderate-intensity exercise among low to moderately active young females. PERSPECTIVE: We examined the influence of self-efficacy on muscle pain during exercise. Although we did not identify a significant influence of efficacy on pain, our research highlights novel research directions. Future research could potentially help identify self-efficacy as a means of decreasing pain during exercise and ultimately enhancing physical activity participation.

Adult↗

PubMed2006

Physical activity and cognitive function in a cross-section of younger and older community-dwelling individuals.

Previous reports have indicated a small, positive relationship between physical activity and cognition. However, the majority of research has focused on older adults, with few studies examining this relationship during earlier periods of the life span. This study examined the relationship of physical activity to cognition in a cross-section of 241 community-dwelling individuals 15-71 years of age with a task requiring variable amounts of executive control. Data were analyzed with multiple regression, which controlled for age, sex, and IQ. Participants reported their physical activity behavior and were tested for reaction time (RT) and response accuracy on congruent and incongruent conditions of a flanker task, which manipulates interference control. After controlling for confounding variables, an age-related slowing of RT was observed during both congruent and incongruent flanker conditions. However, physical activity was associated with faster RT during these conditions, regardless of age. Response accuracy findings indicated that increased physical activity was associated with better performance only during the incongruent condition for the older cohort. Findings suggest that physical activity may be beneficial to both general and selective aspects of cognition, particularly among older adults.

Adolescent↗

PubMed2006

Physical activity and functional limitations in older women: influence of self-efficacy.

This study examined the role of self-efficacy and physical function performance in the relationship between physical activity and functional limitations. Older women (age, M = 68.2 years) completed measures of physical activity, self-efficacy, physical function performance, and functional limitations at the baseline of an ongoing study. Analyses indicated that physical activity was associated with self-efficacy for exercise, efficacy for gait and balance, and physical function performance. Both measures of efficacy and physical functional performance were associated with functional limitations. Demographic and health status variables did not differentially influence these relationships. Although cross-sectional in nature, our findings suggest that physical activity, self-efficacy, and functional performance may all play a role in reducing functional limitations. Of particular relevance is the fact that both physical activity and self-efficacy represent important, modifiable factors that can enhance function.

Activities of Daily Living↗

PubMed2006

Physical activity and quality of life in older adults: influence of health status and self-efficacy.

BACKGROUND: Physical activity has been positively linked to quality of life (QOL) in older adults. Measures of health status and global well-being represent common methods of assessing QOL outcomes, yet little has been done to determine the nature of the relationship of these outcomes with physical activity. PURPOSE: We examined the roles played by physical activity, health status, and self-efficacy in global QOL (satisfaction with life) in a sample of older Black and White women. METHOD: Participants (N = 249, M age = 68.12 years) completed multiple indicators of physical activity, self-efficacy, health status, and QOL at baseline of a 24-month prospective trial. Structural equation modeling examined the fit of 3 models of the physical activity and QOL relationship. RESULTS: Analyses indicated that relationships between physical activity and QOL, self-efficacy and QOL were all indirect. Specifically, physical activity influenced self-efficacy and QOL through physical and mental health status, which in turn influenced global QOL. CONCLUSIONS: Our findings support a social cognitive model of physical activity's relationship with QOL. Subsequent tests of hypothesized relationships across time are recommended.

Aged↗

PubMed2006

Correlates of physical activity among individuals with multiple sclerosis.

BACKGROUND: There is accumulating evidence that individuals with multiple sclerosis (MS) are less physically active than nondiseased populations. One method for increasing the level of participation in physical activity among MS patients involves the identification of factors that correlate with physical activity and that are modifiable by a well-designed intervention. PURPOSE: This study adopts a social cognitive perspective and examines self-efficacy, enjoyment, social support, and disability as correlates of participation in physical activity among individuals with MS. METHODS: We recruited 196 individuals with a diagnosis of MS from the Midwest region of the United States. The participants completed a battery of questionnaires and then wore a belt with an accelerometer for a 7-day period. The data were analyzed using covariance modeling. RESULTS: Enjoyment (gamma=.38, p<.001), social support (gamma=.15, p<.05), and disability (gamma=.18, p<.01) had statistically significant direct relations with self-efficacy, and self-efficacy (beta=.29, p<.001) and enjoyment (gamma=.28, p<.001) had statistically significant direct relations with physical activity. CONCLUSIONS: Future researchers should consider examining self-efficacy and enjoyment as possible components of an intervention that is designed to increase physical activity participation in MS patients.

Disability Evaluation↗

PubMed2006

Structural validity of a self-report concussion-related symptom scale.

PURPOSE: This study evaluated the factorial validity of a self-report measure of concussion-related symptom severity among a large sample of male, high-school athletes. METHODS: Participants (N = 1089) were nonconcussed, male, high-school football players. All participants completed a single baseline self-report measure of concussion-related symptom severity, namely the graded symptom checklist (GSC). We tested the factorial validity of the measure with confirmatory factor analysis using LISREL 8.50. RESULTS: The analysis indicated that a theoretically derived, three-factor model provided a good, but not excellent, fit for the 16-item GSC. Excellent model-data fit was demonstrated for the three-factor model for a 9-item version of the GSC. In both instances, the three factors were best described by a single second-order factor, namely concussion symptomatology. CONCLUSIONS: This study provides additional evidence for the factorial validity of a summative self-reported measure of concussion-related symptoms. The factor structure represents a cohesive group of nine symptoms that can be explained by three underlying latent variables, namely somatic symptoms, neurobehavioral symptoms, and "cognitive" symptoms, subsumed under a single higher-order factor, namely concussion symptoms.

Adolescent↗

PubMed2006

Effect of caffeine on leg muscle pain during cycling exercise among females.

PURPOSE: This double-blind, within-subjects experiment examined the effects of ingesting two doses of caffeine on perceptions of leg muscle pain during moderate-intensity cycling exercise among females. METHODS: Low-caffeine-consuming college-aged females (N = 11) ingested one of two doses of caffeine (5 or 10 mg x kg(-1) body weight) or a placebo and 1 h later completed 30 min of cycling on an ergometer at approximately 60% VO2peak. The conditions were completed in a counterbalanced order. Perceptions of leg muscle pain as well as power output, heart rate, systolic blood pressure, and oxygen consumption (VO2) were recorded during exercise. RESULTS: Caffeine had a significant effect on leg muscle pain ratings [F (2,20) = 10.63, P = 0.001, n2 = 0.52]. The mean pain intensity scores during exercise after ingesting 10 mg x kg(-1) body weight caffeine, 5 mg x kg(-1) body weight caffeine, and placebo were 1.6 +/- 1.1, 1.3 +/- 0.7, and 2.4 +/- 1.1, respectively. CONCLUSION: The results support that caffeine ingestion has a large effect on reducing leg muscle pain during exercise among females, but this effect does not appear to be dose-dependent between 5 and 10 mg.kg body weight caffeine.

Adenosine↗

PubMed2006

Factorial validity and invariance of the center for epidemiologic studies depression (CES-D) scale in a sample of black and white adolescent girls.

Meaningful comparison of depression symptoms requires that the measurement instrument has equivalent measurement properties among racial and ethnic groups. We tested the factorial validity and invariance of the Center for Epidemiologic Studies-Depression (CES-D) Scale among Black (n=610) and White (n=452) adolescent girls in the 12th grade. The invariance analyses were conducted by using LISREL 8.70 with maximum likelihood estimation and Satorra-Bentler scaled chi-square statistics and standard errors. The hypothesized second-order model (first-order factors: depressed affect, somatic and retarded activity, interpersonal, and positive affect; second-order factor: depression) demonstrated good overall fit in both groups. Comparison of nested models supported the between-group invariance of the overall factor structure, first- and second-order factor loadings, first-order factor variances, and the second-order factor variance. Item uniquenesses were not invariant. Our results support the hypothesis that a meaningful comparison of composite CES-D scores can be made between Black and White girls in the 12th grade.

Adolescent↗

PubMed2005

Naturally occurring changes in time spent watching television are inversely related to frequency of physical activity during early adolescence.

In this longitudinal study, we examined the relationship between changes in time spent watching television and playing video games with frequency of leisure-time physical activity across a 2-year period among adolescent boys and girls (N=4594). Latent growth modelling indicated that a decrease in time spent watching television was associated with an increase in frequency of leisure-time physical activity. That relationship was strong in magnitude and independent of sex, socioeconomic status, smoking, and the value participants placed on health, appearance, and achievement. Our results encourage the design of interventions that reduce television watching as a possible means of increasing adolescent physical activity.

Adolescent↗

PubMed2005

Depressive symptoms among older adults: long-term reduction after a physical activity intervention.

We examined the effects of two physical activity modes on depressive symptoms over a 5-year period among older adults and change in physical self-esteem as a mediator of changes in depressive symptoms. Formerly sedentary, older adults (N = 174) were randomly assigned into 6-month conditions of either walking or low-intensity resistance/flexibility training. Depressive symptoms and physical self-esteem were measured before and after the 6-month intervention, and 12 and 60 months after intervention initiation. Depressive symptoms scores were decreased immediately after the intervention, followed by a sustained reduction for 12 and 60 months after intervention initiation; there was no differential pattern of change between the physical activity modes. Change in physical self-esteem predicted change in depressive symptoms. This study supports the effectiveness of an exercise intervention for the sustained reduction of depressive symptoms among sedentary older adults and physical self-esteem as a potential mediator of this effect.

Aged↗

PubMed2005

Self-management strategies mediate self-efficacy and physical activity.

BACKGROUND: Self-efficacy theory proposes that girls who have confidence in their capability to be physically active will perceive fewer barriers to physical activity or be less influenced by them, be more likely to pursue perceived benefits of being physically active, and be more likely to enjoy physical activity. Self-efficacy is theorized also to influence physical activity through self-management strategies (e.g., thoughts, goals, plans, and acts) that support physical activity, but this idea has not been empirically tested. METHODS: Confirmatory factor analysis was used to test the factorial validity of a measure of self-management strategies for physical activity. Next, the construct validity of the measure was tested by examining whether self-management strategies mediated the relationship between self-efficacy and self-reported physical activity, independently of several social-cognitive variables (i.e., perceived barriers, outcome expectancy value, and enjoyment), among cross-sectional samples of 6th grade (n=309) and 8th grade (n=296) girls tested between February 14 and March 17, 2002. Data were analyzed in 2004. RESULTS: Consistent with theory, self-efficacy had direct effects on the social-cognitive variables. The primary novel finding is that self-management strategies mediated the association of self-efficacy with physical activity in both samples. CONCLUSIONS: The measure of self-management strategies for physical activity yields valid scores among adolescent girls and warrants experimental study as a mediator of the influence of efficacy beliefs on physical activity.

Adolescent↗

PubMed2005

Perceived physical environment and physical activity across one year among adolescent girls: self-efficacy as a possible mediator?

PURPOSE: This study involved an examination of the direct and mediated effects of perceived equipment accessibility and neighborhood safety on physical activity across a one-year period among adolescent girls. METHODS: Adolescent girls (N = 1,038) completed self-report measures of perceived environment, barriers self-efficacy, and physical activity in the Spring semesters of 1999 (baseline) and 2000 (follow-up) when students were in the 8th and 9th grades. RESULTS: An initial analysis demonstrated that neighborhood safety did not exhibit cross-sectional or longitudinal direct effects on physical activity, whereas equipment accessibility exhibited a statistically significant cross-sectional, but not longitudinal, direct effect on physical activity. The secondary analysis demonstrated that self-efficacy for overcoming barriers mediated the cross-sectional effect of equipment accessibility on physical activity. CONCLUSIONS: We conclude that the cross-sectional effect of perceived equipment accessibility on physical activity is mediated by self-efficacy for overcoming barriers among adolescent girls. This is consistent with the reciprocal relationships among the environment, person, and behavior described by social-cognitive theory.

Adolescent↗

PubMed2005

Is social desirability associated with self-reported physical activity?

BACKGROUND: Physical activity has been considered to be a socially desirable behavior that might be overreported because of a social desirability bias. This study involved an examination of the possible influence of social desirability on self-report measures of physical activity. METHODS: Participants were male and female college students (N = 782) who completed the Lie scale of the Eysenck Personality Questionnaire (L-scale), Marlowe-Crowne Social Desirability Scale (SDS), Godin Leisure-Time Exercise Questionnaire (GLTEQ), and Stanford Usual Activity Questionnaire. RESULTS: Scores from the Lie scale were not significantly correlated with scores from either the Godin Leisure-Time Exercise Questionnaire or the Stanford Usual Activity Questionnaire. With the Social Desirability Scale, there were statistically significant, but weak correlations with scores from the Godin Leisure-Time Exercise Questionnaire and the Stanford Usual Activity Questionnaire. There was no influence of the Lie scale and Social Desirability Scale on the magnitude of the correlations between scores from the two measures of physical activity. CONCLUSIONS: This study provides minimal evidence of an influence of social desirability on scores from two self-report instruments for measuring physical activity in young adults.

Adaptation, Psychological↗