Dwight E. Waddell

The effect of Tai Chi exercise on gait initiation and gait performance in persons with Parkinson's disease

Gait dysfunction and postural instability are two debilitating symptoms in persons with Parkinsons disease (PD). Tai Chi exercise has recently gained attention as an attractive intervention for persons with PD because of its known potential to reduce falls and improve postural control, walking abilities, and safety at a low cost. The purpose of this report is to investigate the effect of Tai Chi exercise on dynamic postural control during gait initiation and gait performance in persons with idiopathic PD, and to determine whether these benefits could be replicated in two different environments, as complementary projects. In these two separate projects, a total of 45 participants with PD were randomly assigned to either a Tai Chi group or a control group. The Tai Chi groups in both projects completed a 16-week Tai Chi exercise session, while the control groups consisted of either a placebo (i.e., Qi-Gong) or non-exercise group. Tai Chi did not significantly improve Unified Parkinsons Disease Rating Scale Part III score, selected gait initiation parameters or gait performance in either project. Combined results from both projects suggest that 16 weeks of class-based Tai Chi were ineffective in improving either gait initiation, gait performance, or reducing parkinsonian disability in this subset of persons with PD. Thus the use of short-term Tai Chi exercise should require further study before being considered a valuable therapeutic intervention for these domains in PD.

Knee extensor strength, dynamic stability, and functional ambulation: are they related in Parkinson's disease?

OBJECTIVE To evaluate the relationship between knee extensor strength, postural stability, functional ambulation, and disease severity in Parkinsons disease (PD). DESIGN A cohort study. SETTING University research laboratory. PARTICIPANTS Patients (N=44) with idiopathic PD. INTERVENTION Not applicable. MAIN OUTCOME MEASURES Participants were evaluated on their isokinetic knee extensor strength. Additionally, participants completed an assessment of their postural stability (Functional Reach Test for static stability and a dynamic postural stability assessment as measured by the center of pressure-center of mass moment arm during gait initiation). Participants also underwent an evaluation of their functional ambulation as measured by a 6-minute walk test. Lastly, participants were evaluated by a neurologist specially trained in movement disorders to assess neurologic status and disease severity using the Unified Parkinsons Disease Rating Scale and the Hoehn and Yahr disability score. RESULTS Knee extensor strength positively correlated with dynamic postural stability and negatively correlated with disease severity. Further, dynamic postural stability was negatively correlated to disease severity and positively correlated with functional ambulation in this cohort of patients with PD (P<.05). The results also suggest that the Functional Reach Test may be a valuable assessment tool to examine postural stability in PD. CONCLUSIONS These findings suggest a malleable relationship between knee extensor strength, dynamic stability, and disease severity in PD. Although strength is only one piece of the puzzle in the functional outcome of PD, these findings may assist clinicians in designing appropriate interventions aimed at increasing function and decreasing fall risk in PD.

Caffeine’s Ergogenic Effects on Cycling: Neuromuscular and Perceptual Factors

UNLABELLED Caffeine improves endurance exercise performance, but its ergogenic mechanism(s) remain unclear. PURPOSE This investigation sought to examine the effects of caffeine on perceptual and physiological responses to endurance exercise. METHODS Two experiments were performed. In study A, 14 participants were tested. Maximal voluntary strength (MVC) and motor-unit recruitment (%ACT) of the knee extensors and elbow flexors were tested before and 60 min after ingestion of a 5-mg·kg⁻¹ dose of caffeine or placebo and after completion of 40 min of exercise (30 min of submaximal leg or arm cycling followed by a 10-min time-trial performance). Muscle pain, RPE, and cardiorespiratory variables were assessed throughout. To determine the effects of caffeine on muscle pain and RPE during high-intensity exercise, a second study (study B) was performed. Twelve participants exercised at 95% of their gas exchange threshold (GET) and at 70% of the difference between their GET and VO(2peak) (70%Δ) after caffeine and placebo ingestion. RESULTS Compared to placebo, caffeine improved MVC (6.3%, P = 0.014) and %ACT (5.5%, P = 0.013) in the knee extensors, but not the elbow flexors, and reduced muscle pain (P < 0.05) and RPE (P < 0.05) during both submaximal cycling modalities. Caffeine ingestion improved time-trial performance during leg cycling (4.9% ± 6.5%, P = 0.03), but not arm crank cycling (2.1% ± 8.2%, P = 0.28), but the effect on pain and RPE was eliminated. Caffeine ingestion had no effect on pain or RPE during cycling at 95% GET and 70%Δ. CONCLUSIONS Our results suggest that augmented strength and motor-unit recruitment, rather than reductions in pain and effort, may underlie caffeines ergogenic effect on endurance exercise.

Square or sine: finding a waveform with high success rate of eliciting SSVEP

Steady state visual evoked potential (SSVEP) is the brains natural electrical potential response for visual stimuli at specific frequencies. Using a visual stimulus flashing at some given frequency will entrain the SSVEP at the same frequency, thereby allowing determination of the subjects visual focus. The faster an SSVEP is identified, the higher information transmission rate the system achieves. Thus, an effective stimulus, defined as one with high success rate of eliciting SSVEP and high signal-noise ratio, is desired. Also, researchers observed that harmonic frequencies often appear in the SSVEP at a reduced magnitude. Are the harmonics in the SSVEP elicited by the fundamental stimulating frequency or by the artifacts of the stimuli? In this paper, we compare the SSVEP responses of three periodic stimuli: square wave (with different duty cycles), triangle wave, and sine wave to find an effective stimulus. We also demonstrate the connection between the strength of the harmonics in SSVEP and the type of stimulus.

The effects of self-generated synchronous and asynchronous visual speech feedback on overt stuttering frequency

PURPOSE Relatively recent research documents that visual choral speech, which represents an externally generated form of synchronous visual speech feedback, significantly enhanced fluency in those who stutter. As a consequence, it was hypothesized that self-generated synchronous and asynchronous visual speech feedback would likewise enhance fluency. Therefore, the purpose of this study was to investigate the effects of self-generated visual feedback (i.e., synchronous speech feedback with a mirror and asynchronous speech feedback via delayed visual feedback) on overt stuttering frequency in those who stutter. METHOD Eight people who stutter (4 males, 4 females), ranging from 18 to 42 years of age participated in this study. Due to the nature of visual speech feedback, the speaking task required that participants recite memorized phrases in control and experimental speaking conditions so that visual attention could be focused on the speech feedback, rather than a written passage. During experimental conditions, participants recited memorized phrases while simultaneously focusing on the movement of their lips, mouth, and jaw within their own synchronous (i.e., mirror) and asynchronous (i.e., delayed video signal) visual speech feedback. RESULTS Results indicated that the self-generated visual feedback speaking conditions significantly decreased stuttering frequency (Greenhouse-Geisser p=.000); post hoc orthogonal comparisons revealed no significant differences in stuttering frequency reduction between the synchronous and asynchronous visual feedback speaking conditions (p=.2554). CONCLUSIONS These data suggest that synchronous and asynchronous self-generated visual speech feedback is associated with significant reductions in overt stuttering frequency. Study results were discussed relative to existing theoretical models of fluency-enhancement via speech feedback, such as the engagement of mirror neuron networks, the EXPLAN model, and the Dual Premotor System Hypothesis. Further research in the area of self-generated visual speech feedback, as well as theoretical constructs accounting for how exposure to a multi-sensory speech feedback enhances fluency, is warranted. LEARNING OUTCOMES : Readers will be able to (1) discuss the multi-sensory nature of fluency-enhancing speech feedback, (2) compare and contrast synchronous and asynchronous self-generated and externally generated visual speech feedback, and (3) compare and contrast self-generated and externally generated visual speech feedback.

Increased plasma levels of soluble vascular endothelial growth factor receptor 1 (sFlt-1) in women by moderate exercise and increased plasma levels of vascular endothelial growth factor in overweight/obese women.

The incidence of breast cancer is increasing worldwide, and this seems to be related to an increase in lifestyle risk factors, including physical inactivity and overweight/obesity. We have reported previously that exercise induced a circulating angiostatic phenotype characterized by increased soluble fms-like tyrosine kinase-1 (sFlt-1) and endostatin and decreased unbound vascular endothelial growth factor (VEGF) in men. However, there are no data on women. The present study determines the following: (a) whether moderate exercise increased sFlt-1 and endostatin and decreased unbound VEGF in the circulation of adult female volunteers and (b) whether overweight/obese women have a higher plasma level of unbound VEGF than lean women. A total of 72 African American and White adult women volunteers ranging in age from 18 to 44 years were enrolled in the exercise study. All the participants walked on a treadmill for 30 min at a moderate intensity (55–59% heart rate reserve), and oxygen consumption (VO2) was quantified utilizing a metabolic cart. We obtained blood samples before and immediately after exercise from 63 participants. ELISA assays showed that the plasma levels of sFlt-1 were 67.8±3.7 pg/ml immediately after exercise (30 min), significantly higher than the basal levels, 54.5±3.3 pg/ml, before exercise (P<0.01; n=63). There was no significant difference in the % increase in the sFlt-1 levels after exercise between African American and White (P=0.533) women or between lean and overweight/obese women (P=0.892). There was no significant difference in the plasma levels of unbound VEGF (35.28±5.47 vs. 35.23±4.96 pg/ml; P=0.99) or endostatin (111.12±5.48 vs. 115.45±7.15 ng/ml; P=0.63) before and after exercise. The basal plasma levels of unbound VEGF in overweight/obese women were 52.26±9.6 pg/ml, significantly higher than the basal levels of unbound VEGF in lean women, 27.34±4.99 pg/ml (P<0.05). The results support our hypothesis that exercise-induced plasma levels of sFlt-1 could be an important clinical biomarker to explore the mechanisms of exercise training in reducing the progression of breast cancer and that VEGF is an important biomarker in obesity and obesity-related cancer progression.

Steady state visual evoked potentials by dual sine waves

The sum of sine waves was used to evoke Steady State Visual Evoked Potentials (SSVEP). The SSVEP responses were elicited by visual stimuli in the form of a flickering light emitting diode (LED). We recorded EEG responses to these stimuli and analyzed the observed spectral differences due to square waves, triangle waves and sine waves. We showed that the resolution of the dual stimuli, which is defined as the difference between two frequencies, is essential to SSVEP experiments. Reliable dual SSVEP spikes from EEG signals can only be acquired if the dual stimuli are at least 4Hz apart. We also tested tri-stimuli and showed that consistent EEG responses are not achievable, even though the stimuli were 4Hz apart. The essence of these experiments is to demonstrate the resolutions under which dual sine waves can generate consistent SSVEP responses.

Use of analgesics for exercise-associated pain: prevalence and predictors of use in recreationally trained college-aged students.

Abstract Brewer, CB, Bentley, JP, Hallam, JS, Woodyard, CD, and Waddell, DE. Use of analgesics for exercise-associated pain: prevalence and predictors of use in recreationally trained college-aged students. J Strength Cond Res 28(1): 74–81, 2014—The objectives of this study were to examine the use of the analgesics for the relief of exercise-associated pain (EAP) and to examine personal and/or exercise characteristics that might potentially predict such use in recreationally trained college-aged individuals. Recreationally trained college-aged students (N = 263) were invited to complete a self-administered 16-item questionnaire concerning personal exercise habits and analgesic use for EAP. The primary dependent variable was analgesic use for EAP, and additional items sought to characterize patterns and behaviors related to the use. Descriptive statistics and frequencies were calculated for all items, and logistic regression was used to evaluate the ability of 4 variables to predict analgesic use for EAP: gender, length of time performing regular exercise, weekly frequency of aerobic exercise, and weekly frequency of resistance exercise. Approximately 36% of respondents reported analgesic use for EAP, with data indicating acute use for what is generally acute pain. With predictors considered individually, gender was a significant predictor, with female respondents being more likely to use analgesics for EAP (p = 0.04). With all predictors considered concurrently, the model did not significantly contribute to the prediction of use in this sample. Potential for misuse was highlighted by a large percentage of users who described themselves as very unlikely to follow label directions and more likely to take a dose exceeding recommendations. In light of research that reports a potential detriment to muscular regeneration when analgesics are consumed with exercise, it is important to be cognizant of the use of these drugs in individuals striving to improve muscular fitness. Coaches and trainers should educate athletes about the associated risks and caution those who may unnecessarily take analgesics.

Single-Case Design in Psychophysiological Research: Part II: Statistical Analytic Approaches

This article is Part 2 of a two-part series on the conceptual and methodological applications of single-case design research in psychophysiological research (Gustafson, Nassar, & Waddell, 2011). Part 1 in this series presented the context, structure, and fundamentals of single-case design in relation to psychophysiology. Part 2 introduces four statistical analyses that are utilized in single-case research design and are broadly applicable to a wide range of research questions or clinical outcome studies. These techniques are reviewed in sufficient detail so that clinicians and researchers may apply them in real-world contexts. The following analyses—(a) Percentage of Non-overlapping Data Points and Percentage of All Non-overlapping Data, (b) Split-Middle and Percentage of Data Points Exceeding the Median, (c) Improvement Rate Difference, and (d) Hierarchical Linear Modeling—were chosen for their suitability with psychophysiological data. Although these analyses may be unfamiliar, their calculations are qu...

Comparison of energy expenditure to walk or run a mile in adult normal weight and overweight men and women.

Loftin, M, Waddell, DE, Robinson, JH, and Owens, SG. Comparison of energy expenditure to walk or run a mile in adult normal weight and overweight men and women. J Strength Cond Res 24(10): 2794-2798, 2010-We compared the energy expenditure to walk or run a mile in adult normal weight walkers (NWW), overweight walkers (OW), and marathon runners (MR). The sample consisted of 19 NWW, 11 OW, and 20 MR adults. Energy expenditure was measured at preferred walking speed (NWW and OW) and running speed of a recently completed marathon. Body composition was assessed via dual-energy x-ray absorptiometry. Analysis of variance was used to compare groups with the Scheffes procedure used for post hoc analysis. Multiple regression analysis was used to predict energy expenditure. Results that indicated OW exhibited significantly higher (p < 0.05) mass and fat weight than NWW or MR. Similar values were found between NWW and MR. Absolute energy expenditure to walk or run a mile was similar between groups (NWW 93.9 ± 15.0, OW 98.4 ± 29.9, MR 99.3 ± 10.8 kcal); however, significant differences were noted when energy expenditure was expressed relative to mass (MR > NWW > OW). When energy expenditure was expressed per kilogram of fat-free mass, similar values were found across groups. Multiple regression analysis yielded mass and gender as significant predictors of energy expenditure (R = 0.795, SEE = 10.9 kcal). We suggest that walking is an excellent physical activity for energy expenditure in overweight individuals that are capable of walking without predisposed conditions such as osteoarthritis or cardiovascular risk factors. Moreover, from a practical perspective, our regression equation (kcal = mass (kg) × 0.789 − gender (men = 1, women = 2) × 7.634 + 51.109) allows for the prediction of energy expenditure for a given distance (mile) rather than predicting energy expenditure for a given time (minutes).