William G. Werner

Comparison of once-weekly and twice-weekly strength training in older adults.

Background: Strength training has been shown to benefit the health and function of older adults. Objective: To investigate whether one set of exercises performed once a week was as effective in increasing muscle strength as training twice a week. Methods: 18 subjects (7 women and 11 men) aged 65–79 years were randomly assigned to two groups. Both groups performed one set of exercises to muscular fatigue; group 1 trained 1 day/week and group 2 trained 2 days/week on three lower and three upper body exercises for 9 weeks. The data were analysed using a mixed model 2×2 analysis of variance. Results: A significant main effect of time (p<0.001), but not group, on one-repetition maximum scores was observed. No significant interaction was observed between time and group and therefore no difference in strength changes between training once a week versus twice a week after 9 weeks. Conclusions: One set of exercises performed once weekly to muscle fatigue improved strength as well as twice a week in the older adult. Our results provide information that will assist in designing strength-training programmes that are more time and cost efficient in producing health and fitness benefits for older adults.

Cardiovascular response to treadmill testing in Parkinson disease.

Purpose Exercise has been recommended as a way to maintain quality of life in individuals with Parkinson disease (PD). Experiments examining the cardiovascular response to exercise, however, have yielded controversial results. This study was designed to determine if there is any difference in vital signs and Rate of Perceived Exertion (RPE) between a group of individuals (50–80 years old) with PD and a comparison group of healthy individuals during exercise on a treadmill. Methods Twenty seven volunteers (16 with PD and 11 healthy) participated in this study. Subjects with PD were divided into 2 groups; one that reached target heart rate and one that failed to reach it. In this study, heart rate (HR), systolic blood pressure (BP), and the RPE were measured during a Modified Bruce Protocol. We hypothesized that treadmill testing would result in differences between individuals with PD and healthy subjects when HR and systolic BP were compared at submaximal exercise (defined as Stage 2 of the Modified Bruce Protocol) and at peak exercise (defined as 85% of age predicted target heart rate). Results During submaximal exercise, no significant differences were found between the PD group and the control group for HR, B P, or RPE. At peak exercise, one half of the subjects with PD exhibited blunted cardiovascular responses, despite reaching a comparable intensity of exercise during a Modified Bruce Protocol. Conclusions Although cardiovascular responses to exercise on a treadmill appear similar between individuals with PD and controls at lower levels of exercise, half the subjects with PD in the present study displayed abnormal cardiovascular responses at higher exercise intensities. Administering an exercise stress test will illustrate the expected cardiovascular responses for each individual, therefore guiding exercise prescription.

Norepinephrine and Cardiovascular Responses to Maximal Exercise in Parkinson's Disease On and Off Medication

The aim of this experiment is to understand how Parkinsons disease (PD) medication affects the autonomic responses of individuals during an acute exercise stress test. Fourteen people with PD and fifteen healthy individuals age‐matched between 50 and 80 years performed a modified Bruce protocol. Subjects with PD performed the test once off medication (PD‐off) and then 1 week later on medication (PD‐on). Heart rate (HR), blood pressure (BP), VO2, and norepinephrine (NE) levels were taken at rest and at peak exercise. At peak exercise HR, BP, and NE values for the PD‐on and PD‐off group were all significantly lower than healthy controls, regardless of whether subjects were on their medication. Autonomic abnormalities during exercise in this population appear to be disease manifested and not impactedby medications used to treat PD. We can assume, both on and off medication, this population will show markedly lower BP, HR, and NE responses.

Haptic feedback from manual contact improves balance control in people with Parkinson's disease

Parkinsons disease (PD) degrades balance control. Haptic (touch and proprioception) feedback from light contact with a stationary surface inadequate to mechanically stabilize balance improves balance control in healthy people. In this study we tested whether PD impairs use of haptic cues independent of mechanical support to control balance. We measured postural sway in thirteen individuals with PD (H&Y 1-3, median=2, Q1=2, Q3=2) and thirteen age-matched controls balancing in a widened, sharpened Romberg stance in four conditions: eyes-closed, no manual contact; eyes-closed light-touch contact (<1N), eyes-closed, unrestricted contact; and eyes-open, no contact. To determine whether PD-severity affects any of these balance strategies, PD participants were tested on- and off-medication, and using the more- and less-affected body side in the stance and manual contact. Individuals with PD simultaneously maintained non-supportive fingertip contact and balance in this task without practice. PD participants swayed more than control participants (ML CP p=0.010; shoulder p<0.001), but manual contact reduced sway. Non-supportive manual contact stabilized balance more than vision (p<0.05). PD-severity factors had no significant effect (p>0.05). We conclude the effect of PD on balance is not specific to vision or haptic feedback. Nevertheless, haptic cues from manual contact, independent of mechanical support, improve balance control in individuals with PD. We discuss the implication that PD or associated dopaminergic pathways do not directly affect haptic feedback balance control mechanisms, including arm/posture coordination and proprioceptive integration.

Auditory and visual cueing modulate cycling speed of older adults and persons with Parkinson’s disease in a Virtual Cycling (V-Cycle) system

BackgroundEvidence based virtual environments (VEs) that incorporate compensatory strategies such as cueing may change motor behavior and increase exercise intensity while also being engaging and motivating. The purpose of this study was to determine if persons with Parkinson’s disease and aged matched healthy adults responded to auditory and visual cueing embedded in a bicycling VE as a method to increase exercise intensity.MethodsWe tested two groups of participants, persons with Parkinson’s disease (PD) (n = 15) and age-matched healthy adults (n = 13) as they cycled on a stationary bicycle while interacting with a VE. Participants cycled under two conditions: auditory cueing (provided by a metronome) and visual cueing (represented as central road markers in the VE). The auditory condition had four trials in which auditory cues or the VE were presented alone or in combination. The visual condition had five trials in which the VE and visual cue rate presentation was manipulated. Data were analyzed by condition using factorial RMANOVAs with planned t-tests corrected for multiple comparisons.ResultsThere were no differences in pedaling rates between groups for both the auditory and visual cueing conditions. Persons with PD increased their pedaling rate in the auditory (F 4.78, p = 0.029) and visual cueing (F 26.48, p < 0.000) conditions. Age-matched healthy adults also increased their pedaling rate in the auditory (F = 24.72, p < 0.000) and visual cueing (F = 40.69, p < 0.000) conditions. Trial-to-trial comparisons in the visual condition in age-matched healthy adults showed a step-wise increase in pedaling rate (p = 0.003 to p < 0.000). In contrast, persons with PD increased their pedaling rate only when explicitly instructed to attend to the visual cues (p < 0.000).ConclusionsAn evidenced based cycling VE can modify pedaling rate in persons with PD and age-matched healthy adults. Persons with PD required attention directed to the visual cues in order to obtain an increase in cycling intensity. The combination of the VE and auditory cues was neither additive nor interfering. These data serve as preliminary evidence that embedding auditory and visual cues to alter cycling speed in a VE as method to increase exercise intensity that may promote fitness.

Parkinsonian gait ameliorated with a moving handrail, not with a banister.

OBJECTIVE To determine whether haptic (touch and proprioception) cues from touching a moving handrail while walking can ameliorate the gait symptoms of Parkinson disease (PD), such as slowness and small stride length. DESIGN Nonrandomized, controlled before-after trial. SETTING Physical therapy clinic. PARTICIPANTS People with PD (n=16) and healthy age-matched control subjects (n=16) with no neurologic disorders volunteered. No participants withdrew. INTERVENTIONS We compared gait using a moving handrail as a novel assistive aid (speed self-selected) versus a banister and unassisted walking. Participants with PD were tested on and off dopaminergic medication. MAIN OUTCOME MEASURES Mean gait speed, stride length, stride duration, double-support duration, and medial-lateral excursion. RESULTS With the moving handrail, participants with PD increased gait speed relative to unassisted gait by 16% (.166m/s, P=.009, d=.76; 95% confidence interval [CI], .054-.278m/s) and increased stride length by 10% (.053m, P=.022, d=.37; 95% CI, .009-.097m) without significantly changing stride or double-support duration. The banister reduced speed versus unassisted gait by 11% (-.097m/s, P=.040, d=.40; 95% CI, .002-.193m/s) and reduced stride length by 8% (.32m, P=.004, d=.26; 95% CI, .010-.054m), whereas it increased stride duration by 3% (.023s, P=.022, d=.21; 95% CI, .004-.041s) and double-support duration by 35% (.044s, P=.031, d=.58; 95% CI, .005-.083s). All medication × condition interactions were P>.05. CONCLUSIONS Using haptic speed cues from the moving handrail, people with PD walked faster by spontaneously (ie, without specific instruction) increasing stride length without altering cadence; banisters slowed gait. Haptic cues from the moving handrail can be used by people with PD to engage biomechanical and neural mechanisms for interpreting tactile and proprioception changes related to gait speed to control gait better than static cues afforded by banisters.

Effects of Exercise and B Vitamins on Homocysteine and Glutathione in Parkinson’s Disease: A Randomized Trial

Background: Individuals with Parkinson’s disease (PD) have decreased glutathione levels and elevated homocysteine levels. These substances are considered markers of health, and an inverse relationship has been suggested through the transsulfuration pathway. This experiment tested the effects of exercise and B vitamin supplementation on homocysteine and glutathione levels, and if a relationship was present between these two markers in those with PD. Secondary aims included examining the impact of the interventions on aerobic efficiency and strength. Methods: Thirty-six subjects were randomly assigned to 4 groups. The Vit group received vitamins B6, B12 and folic acid daily for 6 weeks. The Ex group received aerobic and strength training twice weekly for 6 weeks. The Vit + Ex group received both interventions. A control group received no intervention. Subjects were tested prior to and after intervention on the following measures: glutathione and homocysteine levels, strength measures and oxygen consumption. Results: Subjects who received 6 weeks of B vitamin supplementation had lowered homocysteine levels. Subjects who received 6 weeks of exercise training had increased glutathione levels, strength and aerobic capacity. The combination of vitamin and exercise did not yield greater changes than the separate intervention. The control subjects did not change on any measures. Conclusion: Positive results were realized with each intervention; however, the expected relationship between glutathione and homocysteine was not found in this sample of subjects with PD. Homocysteine and glutathione levels can be improved independently in individuals with PD with exercise or vitamins B6, B12 and folic acid supplementation.

Influence of cueing, feedback and directed attention on cycling in a virtual environment: Preliminary findings in healthy adults and persons with Parkinson's disease

Evidence based virtual environments that incorporate motor learning and compensatory strategies such as feedback and cueing may change motor behavior while also being engaging and motivating. Although virtual environments have been used for exercise promotion in healthy people and persons with stroke, its use for fitness in persons with PD has not been investigated. Further a specific understanding of embedding cueing and feedback in a virtual environment is absent. METHOD: We tested two groups of participants, older adults (n=4) and people with Parkinsons disease (n=4) as they cycled on a stationary bicycle while interacting with a virtual environment. Participants cycled under 4 conditions; auditory cueing, visual cueing, feedback, and directed attention. Data between groups were analyzed using a 2 × 2 factorial RM ANOVA and within groups using a RMANOVA with post-hoc t-tests corrected for multiple comparisons. RESULTS: There were no between group differences, however, within groups healthy older adults increased their cycling speed in the auditory cueing (F 21.59, p=0.000) and directed attention conditions (F 6.04, p=0.030). For people with PD pedaling rate increased in the auditory cueing (F 4.78, p=0.029, visual cueing (F 26.48, p<;0.000), feedback (F 18.77, p<;0.000), and directed attention conditions (F 27.65, p<;0.000). These data serve as preliminary validation of embedding cues, feedback to alter cycling speed in a VE. Further, the role of directing attention to the cues enhances cycling performance.

Effects of Tyrosine on Parkinson's Disease: A Randomized, Double-Blind, Placebo-Controlled Trial

Individuals with Parkinsons disease (PD) can suffer from orthostatic hypotension (OH) resulting from reduced levels of norepinephrine (NE), which inhibits the sympathetic nervous system. Levodopa reduces NE levels even further, leading to a greater decrease in blood pressure (BP) and increased OH. Tyrosine is a nonessential amino acid that is the major precursor to NE. Reduced levels of tyrosine have been shown after administration of l‐dopa. This study was a single‐center, randomized, double‐blind, placebo‐controlled trial to test the effects of supplementing l‐tyrosine on BP, plasma tyrosine, NE levels, and autonomic responses to exercise in PD. Thirty‐six subjects with PD receiving l‐dopa medication that suffer from OH participated. Random assignment was to a placebo group or l‐tyrosine 1,000 mg (500 mg of 2× daily) group for 7 days. OH testing and exercise testing was performed pre‐ and postsupplementation. There was no effect of tyrosine on BP after OH testing postsupplementation (tyrosine, n = 17; placebo, n = 19). There was an increase in plasma tyrosine in the tyrosine group (P > 0.05). There were no significant changes in any of the secondary outcome measures. l‐tyrosine at 1,000 mg (500 mg/2× day) for 7 days is safe and well tolerated in PD. Our results were inconclusive as to whether an increase in plasma tyrosine has an effect on OH in subjects with PD. An increase in plasma tyrosine had no effect on BP or autonomic responses in subjects with PD during acute exercise stress. (Trial registration: ClinicalTrials.gov.; identifier: NCT01676103)

Gait parameter control timing with dynamic manual contact or visual cues

We investigated the timing of gait parameter changes (stride length, peak toe velocity, and double-, single-support, and complete step duration) to control gait speed. Eleven healthy participants adjusted their gait speed on a treadmill to maintain a constant distance between them and a fore-aft oscillating cue (a place on a conveyor belt surface). The experimental design balanced conditions of cue modality (vision: eyes-open; manual contact: eyes-closed while touching the cue); treadmill speed (0.2, 0.4, 0.85, and 1.3 m/s); and cue motion (none, ±10 cm at 0.09, 0.11, and 0.18 Hz). Correlation analyses revealed a number of temporal relationships between gait parameters and cue speed. The results suggest that neural control ranged from feedforward to feedback. Specifically, step length preceded cue velocity during double-support duration suggesting anticipatory control. Peak toe velocity nearly coincided with its most-correlated cue velocity during single-support duration. The toe-off concluding step and double-support durations followed their most-correlated cue velocity, suggesting feedback control. Cue-tracking accuracy and cue velocity correlations with timing parameters were higher with the manual contact cue than visual cue. The cue/gait timing relationships generalized across cue modalities, albeit with greater delays of step-cycle events relative to manual contact cue velocity. We conclude that individual kinematic parameters of gait are controlled to achieve a desired velocity at different specific times during the gait cycle. The overall timing pattern of instantaneous cue velocities associated with different gait parameters is conserved across cues that afford different performance accuracies. This timing pattern may be temporally shifted to optimize control. Different cue/gait parameter latencies in our nonadaptation paradigm provide general-case evidence of the independent control of gait parameters previously demonstrated in gait adaptation paradigms.