Julie A. Robichaud

A two-year randomized controlled trial of progressive resistance exercise for Parkinson's disease

The effects of progressive resistance exercise (PRE) on the motor signs of Parkinsons disease have not been studied in controlled trials. The objective of the current trial was to compare 6‐, 12‐, 18‐, and 24‐month outcomes of patients with Parkinsons disease who received PRE with a stretching, balance, and strengthening exercise program. The authors conducted a randomized controlled trial between September 2007 and July 2011. Pairs of patients matched by sex and off‐medication scores on the Unified Parkinsons Disease Rating Scale, motor subscale (UPDRS‐III), were randomly assigned to the interventions with a 1:1 allocation ratio. The PRE group performed a weight‐lifting program. The modified fitness counts (mFC) group performed a stretching, balance, and strengthening exercise program. Patients exercised 2 days per week for 24 months at a gym. A personal trainer directed both weekly sessions for the first 6 months and 1 weekly session after 6 months. The primary outcome was the off‐medication UPDRS‐III score. Patients were followed for 24 months at 6‐month intervals. Of 51 patients, 20 in the PRE group and 18 in the mFC group completed the trial. At 24 months, the mean off‐medication UPDRS‐III score decreased more with PRE than with mFC (mean difference, −7.3 points; 95% confidence interval, −11.3 to −3.6; P<0.001). The PRE group had 10 adverse events, and the mFC group had 7 adverse events. PRE demonstrated a statistically and clinically significant reduction in UPDRS‐III scores compared with mFC and is recommended as a useful adjunct therapy to improve Parkinsonian motor signs.

Effect of medication on EMG patterns in individuals with Parkinson's disease

Individuals with Parkinsons disease show dramatic improvements in their ability to move when medicated. However, the neural cause of this improvement is unclear. One hypothesis is that neural activation patterns, as measured by surface electromyography (EMG), are normalized by medication. We tested this hypothesis by investigating the effect of medication on the electromyographic (EMG) patterns recorded when individuals with idiopathic Parkinsons disease performed elbow flexion movements over three movement distances while off and on antiparkinsonian medication. When the subjects were off medication, they lacked the ability to modulate the agonist EMG burst duration with changes in movement distance. The ability to modulate agonist EMG burst duration is characteristic of the EMG patterns observed in healthy subjects. Also, multiple agonist bursts were exhibited during the acceleration phase. As expected, medication diminished the clinical signs of Parkinsons disease, increased movement speed, and increased the magnitude of the first agonist burst. Medication did not restore agonist burst duration modulation with movement distance, did not change the frequency of agonist bursting, and did not alter the timing of the antagonist activation. These results show that medication does not alter the temporal profile of EMG activation.

Exercise improves cognition in Parkinson's disease: The PRET-PD randomized, clinical trial.

This article reports on the findings of the effect of two structured exercise interventions on secondary cognitive outcomes that were gathered as part of the Progressive Resistance Exercise Training in Parkinsons disease (PD) randomized, controlled trial.

Greater impairment of extension movements as compared to flexion movements in Parkinson's disease

Research on isometric contractions in subjects with Parkinson’s disease (PD) has shown that anti-parkinsonian medication results in a greater increase in extensor strength than flexor strength. This finding is consistent with the hypothesis that there is a greater impairment in neural activation of extensor muscles as compared to flexor muscles in subjects with PD. Such a hypothesis is physiologically feasible given the known differences in the neural control of flexor and extensor muscles. If the above hypothesis is true for both phasic and tonic muscle activation, then differences between performance of rapid single-joint flexion and extension movements should exist in subjects with PD. Twelve subjects with PD, “off” and “on” medication, and 12 age- and sex-matched healthy control subjects performed rapid single-joint movements in flexion and extension over three distances. For neurologically healthy subjects, we did not identify any significant differences in either kinematic or EMG parameters between flexion and extension movements. In contrast, in the PD subjects extension movements were slower and associated with more agonist bursts when compared to flexion movements. The results are consistent with the hypothesis that there is a differential impairment of neural activation of extensor muscles of the arm as compared to flexor muscles in subjects with PD.

Two-year exercise program improves physical function in Parkinson's disease: the PRET-PD randomized clinical trial.

Background. The progressive resistance exercise (PRE) in Parkinson’s disease trial (PRET-PD) showed that PRE improved the motor signs of PD compared to a modified Fitness Counts (mFC) program. It is unclear how long-term exercise affects physical function in these individuals. Objective. To examine the effects of long-term PRE and mFC on physical function outcome measures in individuals with PD. Methods. A preplanned secondary analysis was conducted using data from the 38 patients with idiopathic PD who completed the PRET-PD trial. Participants were randomized into PRE or mFC groups and exercised 2 days/week up to 24 months. Blinded assessors obtained functional outcomes on and off medication at baseline, 6 and 24 months with the Modified Physical Performance Test, 5 times sit to stand test, Functional Reach Test, Timed Up and Go, Berg Balance Scale, 6 minute walk test (6MWT), and 50-ft walking speed (walk speed). Results. The groups did not differ on any physical function measure at 6 or 24 months (Ps > .1). Across time, all physical function measures improved from baseline to 24 months when tested on medication (Ps < .0001), except for 6MWT (P = .068). Off medication results were similar except that the 6MWT was now significant. Conclusions. Twenty-four months of supervised and structured exercise (either PRE or mFC) is effective at improving functional performance outcomes in individuals with moderate PD. Clinicians should strive to include structured and supervised exercise in the long-term plan of care for individuals with PD.

Progressive Resistance Exercise and Parkinson's Disease: A Review of Potential Mechanisms

This paper reviews the therapeutically beneficial effects of progressive resistance exercise (PRE) on Parkinsons disease (PD). First, this paper discusses the rationale for PRE in PD. Within the first section, the review discusses the central mechanisms that underlie bradykinesia and muscle weakness, highlights findings related to the central changes that accompany PRE in healthy individuals, and extends these findings to individuals with PD. It then illustrates the hypothesized positive effects of PRE on nigro-striatal-thalamo-cortical activation and connectivity. Second, it reviews recent findings of the use of PRE in individuals with PD. Finally, knowledge gaps of using PRE on individuals with PD are discussed along with suggestions for future research.

Variability of EMG patterns: a potential neurophysiological marker of Parkinson's disease?

OBJECTIVE This study evaluated whether changes in the electromygraphic (EMG) pattern during rapid point-to-point movements in individuals diagnosed with PD can: (1) distinguish PD subjects from healthy subjects and (2) determine if differences in the EMG pattern reflect disease severity in PD. METHODS Three groups of 10 PD subjects and 10 age/sex-matched healthy subjects performed rapid 72 degree point-to-point elbow flexion movements. PD subjects were divided, a priori, into three groups based upon off medication motor UPDRS score. RESULTS Measures related to the EMG pattern distinguished all PD subjects and 9 out of 10 healthy subjects, resulting in 100% sensitivity. Further, significant correlations were shown between EMG measures and the motor UPDRS score. After 30 months, the one healthy subject whose EMG pattern was abnormal was reexamined. The EMG measures remained abnormal and the motor UPDRS score went from 0 to 10. Parkinsons disease was diagnosed. CONCLUSION Measures related to the variability of the EMG pattern during rapid point-to-point movements provide neurophysiological measures that objectively distinguish PD subjects from healthy subjects. These measures also correlate with disease severity. SIGNIFICANCE EMG measures may provide a non-invasive measure that is sensitive and specific for identifying individuals with PD.

Two-Year Exercise Program Improves Physical Function in Parkinson’s Disease

Background. The progressive resistance exercise (PRE) in Parkinson’s disease trial (PRET-PD) showed that PRE improved the motor signs of PD compared to a modified Fitness Counts (mFC) program. It is unclear how long-term exercise affects physical function in these individuals. Objective. To examine the effects of long-term PRE and mFC on physical function outcome measures in individuals with PD. Methods. A preplanned secondary analysis was conducted using data from the 38 patients with idiopathic PD who completed the PRET-PD trial. Participants were randomized into PRE or mFC groups and exercised 2 days/week up to 24 months. Blinded assessors obtained functional outcomes on and off medication at baseline, 6 and 24 months with the Modified Physical Performance Test, 5 times sit to stand test, Functional Reach Test, Timed Up and Go, Berg Balance Scale, 6 minute walk test (6MWT), and 50-ft walking speed (walk speed). Results. The groups did not differ on any physical function measure at 6 or 24 months (Ps > .1). Across time, all physical function measures improved from baseline to 24 months when tested on medication (Ps < .0001), except for 6MWT (P = .068). Off medication results were similar except that the 6MWT was now significant. Conclusions. Twenty-four months of supervised and structured exercise (either PRE or mFC) is effective at improving functional performance outcomes in individuals with moderate PD. Clinicians should strive to include structured and supervised exercise in the long-term plan of care for individuals with PD.

Combined measures of movement and force variability distinguish Parkinson’s disease from essential tremor

OBJECTIVE To examine whether behavioral and electrophysiological measures of motor performance accurately differentiate Parkinsons disease (PD) and essential tremor (ET). METHODS Twenty-four patients (12 PD; 12 ET) performed isometric force, ballistic movements, and tremor tasks. Receiver operating characteristic (ROC) analyses were conducted on all dependent measures that were significantly different between the two patient groups. RESULTS Patients with PD were more impaired on measures of movement deceleration than ET. Patients with ET were more impaired on measures of force variability than PD. ROC analyses revealed that sensitivity and specificity were excellent when combining measures during the isometric force task (torque rise time and force variability; 92% sensitivity and 92% specificity; AUC = 0.97). When combining measures across the force and movement tasks, the ROC analysis revealed improved sensitivity and specificity (force variability and peak deceleration; 92% sensitivity and 100% specificity; AUC = 0.99). CONCLUSIONS Combining measures of force variability and movement deceleration accurately differentiate patients with PD from those with ET with high sensitivity and specificity. SIGNIFICANCE If validated in a larger sample, these measures can serve as markers to confirm the diagnosis of PD or ET and thus, enhance decision making for appropriate treatments for patients with these respective diseases.

Progressive resistance exercise restores some properties of the triphasic EMG pattern and improves bradykinesia: the PRET-PD randomized clinical trial

In Parkinsons disease (PD), the characteristic triphasic agonist and antagonist muscle activation pattern during ballistic movement is impaired: the number of agonist muscle bursts is increased, and the amplitudes of the agonist and antagonist bursts are reduced. The breakdown of the triphasic electromyographic (EMG) pattern has been hypothesized to underlie bradykinesia in PD. Progressive resistance exercise has been shown to improve clinical measures of bradykinesia, but it is not clear whether the benefits for bradykinesia are accompanied by changes in agonist and antagonist muscle activity. This study examined the spatiotemporal changes in agonist and antagonist muscle activity following 24 mo of progressive resistance exercise and the combined relationship between spatiotemporal muscle activity and strength measures and upper limb bradykinesia. We compared the effects of progressive resistance exercise training (PRET) with a nonprogressive exercise intervention, modified Fitness Counts (mFC), in patients with PD. We randomized 48 participants with mild-to-moderate PD to mFC or PRET. At the study endpoint of 24 mo, participants randomized to PRET compared with mFC had significantly faster movement velocity, accompanied by significant increases in the duration, magnitude, and magnitude normalized to duration of the 1st agonist burst and fewer number of agonist bursts before peak velocity. The antagonist muscle activity was increased relative to baseline but did not differ between groups. Spatiotemporal EMG muscle activity and muscle strength were significantly associated with upper limb bradykinesia. These findings demonstrate that progressive resistance exercise improves upper limb movement velocity and restores some aspects of the triphasic EMG pattern.