Susan S. Levy

Translating physical activity recommendations into a pedometer-based step goal: 3000 steps in 30 minutes.

BACKGROUND It is a public health recommendation to accumulate at least 150 minutes per week of moderate intensity physical activity. Although pedometers are widely used as a physical activity-monitoring tool, they are unable to measure activity intensity. Translating current physical activity recommendations into a pedometer-based guideline could increase the public health impact of physical activity interventions. METHODS A community sample of 97 adults (60% women, with a mean age of 32.1 [+/-10.6] years and a mean BMI of 28.8 [+/-5.5]) completed four 6-minute incremental walking bouts on a level treadmill at 65, 80, 95, and 110 m x min(-1). A calibrated metabolic cart was used to measure energy expenditure at each speed. Steps were measured using a Yamax SW-200 pedometer. Step-rate cut points associated with minimally moderate-intensity activity (defined as 3 METs) were determined using multiple regression, mixed modeling, and receiver operating characteristic (ROC) curves. All data were collected and analyzed in 2006. RESULTS For men, step counts per minute associated with walking at 3 METs were 92 step x min(-1) (multiple regression); 101 step x min(-1) (mixed modeling); and 102 step x min(-1) (ROC curve). For women, step counts per minute associated with walking at 3 METs were 91 step x min(-1) (multiple regression); 111 step x min(-1) (mixed modeling); and 115 step x min(-1) (ROC curve). However, for each analysis there was substantial error in model fit. CONCLUSIONS Moderate-intensity walking appears approximately equal to at least 100 step x min(-1). However, step counts per minute is a poor proxy for METs, and so 100 step x min(-1) should be used only as a general physical activity promotion heuristic. To meet current guidelines, individuals are encouraged to walk a minimum of 3000 steps in 30 minutes on 5 days each week. Three bouts of 1000 steps in 10 minutes each day can also be used to meet the recommended goal.

Ventilatory and metabolic demands during aggressive physical restraint in healthy adults.

ABSTRACT: We investigated ventilatory and metabolic demands in healthy adults when placed in the prone maximal restraint position (PMRP), i.e., hogtie restraint. Maximal voluntary ventilation (MVV) was measured in seated subjects (n=30), in the PMRP, and when prone with up to 90.1 or 102.3 kg of weight on the back. MVV with the heaviest weight was 70% of the seated MVV (122±28 and 156±38 L/min, respectively; p<0.001). Also, subjects (n=27) were placed in the PMRP and struggled vigorously for 60 sec. During the restrained struggle, ventilatory function (V̇E/ MVV) was 44% of MVV in the resting PMRP. While prone with up to 90.1 or 102.3 kg on the back, the decrease in MVV was of no clinical importance in these subjects. Also, while maximally struggling in the PMRP, V̇E was still adequate to supply the ventilatory needs.

An alternative to the balance error scoring system: using a low-cost balance board to improve the validity/reliability of sports-related concussion balance testing.

Objective:Recent guidelines advocate sports medicine professionals to use balance tests to assess sensorimotor status in the management of concussions. The present study sought to determine whether a low-cost balance board could provide a valid, reliable, and objective means of performing this balance testing. Design:Criterion validity testing relative to a gold standard and 7 day test-retest reliability. Setting:University biomechanics laboratory. Participants:Thirty healthy young adults. Assessment of Risk Factors:Balance ability was assessed on 2 days separated by 1 week using (1) a gold standard measure (ie, scientific grade force plate), (2) a low-cost Nintendo Wii Balance Board (WBB), and (3) the Balance Error Scoring System (BESS). Main Outcome Measures:Validity of the WBB center of pressure path length and BESS scores were determined relative to the force plate data. Test-retest reliability was established based on intraclass correlation coefficients. Results:Composite scores for the WBB had excellent validity (r = 0.99) and test-retest reliability (R = 0.88). Both the validity (r = 0.10–0.52) and test-retest reliability (r = 0.61–0.78) were lower for the BESS. Conclusions:These findings demonstrate that a low-cost balance board can provide improved balance testing accuracy/reliability compared with the BESS. Clinical Relevance:This approach provides a potentially more valid/reliable, yet affordable, means of assessing sports-related concussion compared with current methods.

Motor Response Programming and Movement Time in Children with Heavy Prenatal Alcohol Exposure

The present experiment assessed motor response programming and movement time in children with histories of heavy prenatal alcohol exposure (PEA). Alcohol-exposed children between the ages of 7 and 17 years were classified into two groups: Fetal Alcohol Syndrome (FAS: n=9) and children with PEA (PEA: n=19) but who did not have the defining characteristics of FAS. The FAS and PEA children were compared with non-alcohol-exposed children (NC: n=23) when completing two tasks: a simple reaction time task (RT alone condition) and a reaction plus movement task (RT+Move condition). The movement involved responding to an imperative stimulus signal and depressing three target buttons in a set sequence. Participants completed 24 trials each for the RT alone and RT+Move response conditions. Results indicated no significant differences in performance among FAS, PEA, and NC groups during the RT alone condition. However, during the RT+Move condition, the FAS group produced significantly longer and more variable RTs than the PEA and NC groups, which produced comparable RTs. The FAS group also produced significantly slower movement times when moving to all three targets, whereas movement time variability did not significantly differ as a function of group. The observed results indicate children with FAS experience deficits in response programming and movement time production.

Factors Associated with Transitional Shifts in College Students' Physical Activity Behavior.

The Transtheoretical Model (Prochaska & Marcus, 1994) has been widely used as a framework for understanding exercise behavior change. The purpose of this study was to clarify equivocal research findings reported for model predictions when examining stage movement over time rather than static stages and to provide some evidence of the construct validity of transitional stages. Participants were female (n = 285) and male (n = 243) undergraduates (M age = 19.9 years, SD = 2.7) who completed previously validated questionnaires twice, separated by 9 weeks, that assessed stage of change, exercise behavior, processes of change, pros and cons of exercise, and exercise self-efficacy. Participants were classified into one of five transitional shift groups based on their responses at baseline and follow up: (a) stable sedentary, (b) stable active, (c) activity adopters, (d) activity relapsers, and (e) perpetual preparers. Results of a 5 (group) x 2 (time) repeated measures (RM) analysis of variance (ANOVA) examining exercise behavior revealed a significant interaction (p < .001) and supported transitional stage classification, with activity adopters and stable actives increasing exercise over time and relapsers decreasing activity. Separate 5 (group) x 2 (time) RM ANOVAs examining model constructs revealed no significant interaction for cognitive processes of change; however, activity adopters and stable actives reported significant (p < .01) increases in the use of behavioral processes over time, while only the activity relapsers and perpetual preparers reported decreases. Activity relapsers also reported significant (p < .05) decreases in the pros of exercise. No significant interactions were found for the cons of exercise behavior. Unlike findings reported in cross-sectional studies, increases in self-efficacy did not accompany increases in exercise stage. The findings strongly support examination of stage movement classifications rather than static stages, as these transitions provide greater insight into the mechanisms of exercise behavior change.

Transitional shifts in exercise behavior among women with multiple sclerosis

BACKGROUND While physical activity is recommended to reduce symptomology associated with multiple sclerosis (MS) little has been done to explore the potential usefulness of theoretical models of exercise behavior change in individuals with MS. Based on the success of the transtheoretical model of exercise behavior change (TTM) in the general population and early promising results in those with MS, the TTM was tested in a sample of women with MS over a 1-year period, to examine its usefulness and the effect of TTM constructs on MS-related symptoms. METHODS This was a longitudinal study conducted over a 1-year period. Ambulatory women (N=86) with MS completed questionnaires assessing exercise behavior, TTM constructs, MS-related quality of life, pain, and fatigue at baseline and after 1 year. After categorization into transitional shift patterns reflecting naturally occurring exercise behavior change over the year, a series of mixed-design analyses of variance were conducted to examine TTM predictions and the relationship of the transitional shift patterns to MS-related quality of life, pain, and fatigue. RESULTS Significant interactions between transitional shift patterns and time (P < .05) indicated that changes in behavioral and cognitive processes of change and in self-efficacy were consistent with TTM predictions. Significant differences (P < .05) between the transitional shift groups in pain and fatigue in expected directions were also found. CONCLUSIONS Results supported the TTM proposed relationships, indicating the models potential for motivating individuals with MS to increase their physical activity. Findings also support the notion that physical activity is useful in reducing MS-related symptoms and that lifestyle types of physical activity may be as useful as structured exercise in bringing about these outcomes.

Evaluation of a multi-component group exercise program for adults with arthritis: Fitness and Exercise for People with Arthritis (FEPA).

BACKGROUND Research supports the favorable effects of exercise on physical and psychosocial outcomes in those with arthritis. Few easily disseminated, multi-component, arthritis-specific programs have been evaluated using both physical function and psychosocial measures. Fitness and Exercise for People with Arthritis (FEPA) is a new community-based, 3-month, instructor supervised multi-component exercise program for individuals with arthritis designed to increase strength, flexibility, balance, and aerobic conditioning, while emphasizing joint-protection and proper biomechanics. PURPOSE To conduct a preliminary evaluation of the effects of the FEPA program on physical function and arthritis-related outcomes in individuals with arthritis. METHOD Middle-aged (n = 31, M(age) = 54.8 ± 7.2) and older (n = 79, M(age) = 76.0 ± 6.6) adults with arthritis completed the instructor led FEPA program in community senior centers, churches, and adult education settings. Changes in physical function, measured using the arm curl, back-scratch test, 8-foot up-and-go, and 6 min walk and self-reported arthritis-related pain, perceived physical function, affect, and self-efficacy for symptom management were assessed using RM ANOVA. RESULTS Significant improvements (ps < .05) in all physical function measures were found in the older group. In the middle-aged group, significant improvements (ps < .05) were found in the 8-foot up-and-go and 6 min walk. Self-reported physical function, pain perceptions, and self-efficacy for pain management significantly improved (ps < .05) in middle-aged participants, while only self-reported pain perceptions significantly improved in the older group. CONCLUSIONS FEPA shows promise for improving health-related outcomes in those with arthritis, and has potential for sustainability in community settings.

Children with Heavy Prenatal Alcohol Exposure Exhibit Deficits when Regulating Isometric Force

BACKGROUND Production of isometric (i.e., constant) force is an essential component of performing everyday functional tasks, yet no studies have investigated how this type of force is regulated in children with confirmed histories of heavy prenatal alcohol exposure. METHODS Children 7 to 17 years old with heavy prenatal alcohol exposure (n = 25) and without exposure (n = 18) applied force to a load cell to generate an isometric force that matched a criterion target force displayed on a computer monitor. Two levels of target force were investigated in combination with 3 levels of visual feedback frequency that appeared on the computer monitor as a series of yellow dots. Force was maintained for 20 seconds and participants completed 6 trials per test condition. RESULTS Root-mean-square error, signal-to-noise ratio, and sample entropy indexed response accuracy, response variability, and signal complexity, respectively. The analyses revealed that in comparison with controls, children with gestational ethanol exposure were significantly less accurate and more variable in regulating their force output and generated a response signal with greater regularity and less complexity in the time domain. CONCLUSIONS Children with prenatal alcohol exposure experience significant deficits in isometric force production that may impede their ability to perform basic motor skills and activities in everyday tasks.

Wii Fit exer-game training improves sensory weighting and dynamic balance in healthy young adults

The Nintendo Wii Fit is a balance training tool that is growing in popularity due to its ease of access and cost-effectiveness. While considerable evidence now exists demonstrating the efficacy of the Wii Fit, no study to date has determined the specific mechanism underlying Wii Fit balance improvement. This paucity of knowledge was addressed in the present study using the NeuroCom Balance Managers Sensory Organization Test (SOT) and Limits of Stability (LOS) test. These well-recognized posturography assessments, respectively, measure sensory weighting and dynamic stability mechanisms of balance. Forty healthy, young participants were recruited into two groups: Wii Fit Balance Intervention (WFBI) (n=20) and Control (CON) (n=20). Balance training consisted of seven Wii Fit exer-games played over the course of six consecutive weeks (2-4×/week, 30-45min/day). The WFBI group performed Neurocom testing before and after the intervention, while the CON group was tested along a similar timeline with no intervention. Mixed-design ANOVAs found significant interactions for testing time point and condition 5 of the SOT (p<0.02), endpoint excursion (p<0.01), movement velocity (p<0.02), and response time (p<0.01). These effects were such that greater improvements were seen for the WFBI group following Wii Fit training. These findings suggest that individuals with known issues regarding the processing of multiple sources of sensory information and/or who have limited functional bases of support may benefit most from Wii Fit balance training.

Effects of Sodium Bicarbonate on V̇o2 Kinetics during Heavy Exercise

PURPOSE Sodium bicarbonate was used to investigate the effect of blood pH on VO2 kinetics during heavy exercise. METHODS On separate days, 10 active subjects performed two 6-min cycling bouts (208 +/- 12 W) at 25 W above their ventilatory threshold. Each subject ingested 0.3 g x kg(-1) of sodium bicarbonate with approximately 1 L of water or water alone 1 h before exercise. VO2 kinetics were examined by means of a three-component mono-exponential model. RESULTS Bicarbonate ingestion caused a significant increase in the preexercise blood pH (7.512 +/- 0.009 vs 7.425 +/- 0.007; P < 0.001). In the bicarbonate trial, the time constant for the rapid component (27.9 +/- 3.5 s) was slower than the control trial (20.8 +/- 2.4 s; P = 0.017). The higher blood pH after bicarbonate ingestion would have diminished local blood flow and caused a leftward shift of the oxygen-hemoglobin dissociation curve both of which would slow oxygen delivery to working muscle. In addition, bicarbonate ingestion diminished the amplitude of the slow component 29% (463 +/- 43 vs 649 +/- 53 mL x min(-1); P = 0.040). The primary cause of the slow component during heavy exercise is fatigue of working fibers and an accompanying increase of motor unit recruitment. Elevated plasma bicarbonate concentration is reported to stimulate the efflux of H from muscle fibers and to increase intramuscular pH. CONCLUSIONS The slower time constant during the rapid component suggested that oxygen delivery is a limiting factor of VO2 kinetics during the onset of heavy exercise. Also, these results imply that bicarbonate ingestion diminished fatigue in working fibers during the slow component.