Strength in Parkinson's disease: relationship to rate of force generation and clinical status

Short-term effects of Pilates-based exercise on upper limb strength and function in people with Parkinson's disease

BACKGROUND

People with Parkinson's disease (PD) have impaired upper limb motor coordination, limiting the execution of activities of daily living. This study investigated the feasibility and safety of a short-term Pilates-based exercise program in the treatment of upper limb motor coordination for people with PD.

METHODS

Fifteen patients - n (%) 4 women/11 men (27/73), median [interquartile range] age 66 [9] years - participated in this quasi-experimental (before-and-after) clinical trial. Patients underwent a 6-week (30 min/day, 3 days/week) Pilates exercise program using Reformer, Cadillac, Chair, and Barrel equipment. Feasibility was evaluated by adherence to the program and the ability to perform the exercises including progressions on difficulty. Safety was evaluated based on self-reported adverse events. Clinical and functional trends before and after the intervention were also computed regarding handgrip strength (HGS), fine motor coordination (9 Hole Peg Test; 9HPT), bradykinesia (Movement Disorder Society - Unified Parkinson's disease Rating Scale; MDS-UPDRS), and upper limb functionality (Test D'évaluation des Membres Supérieurs des Personnes Âgées, TEMPA).

RESULTS

Of the 18 Pilates sessions, exercise adherence was 100%. The only adverse event observed was mild muscle pain. Pre-post differences were observed only for body bradykinesia and hypokinesia (1.0 [0.0] vs. 0.0 [1.0] s, adjusted p = 0.048).

CONCLUSIONS

A short-term Pilates-based exercise program in the treatment of upper limb muscle strength, manual dexterity, bradykinesia, and functionality is feasible and safe for people with PD. Changes in upper limb bradykinesia encourage randomized clinical trials.

Impaired performance of rapid grip in people with Parkinson's disease and motor segmentation

Bradykinesia, or slow movement, is a defining symptom of Parkinson's disease (PD), but the underlying neuromechanical deficits that lead to this slowness remain unclear. People with PD often have impaired rates of motor output accompanied by disruptions in neuromuscular excitation, causing abnormal, segmented, force-time curves. Previous investigations using single-joint models indicate that agonist electromyogram (EMG) silent periods cause motor segmentation. It is unknown whether motor segmentation is evident in more anatomically complex and ecologically important tasks, such as handgrip tasks. Aim 1 was to determine how handgrip rates of force change compare between people with PD and healthy young and older adults. Aim 2 was to determine whether motor segmentation is present in handgrip force and EMG measures in people with PD. Subjects performed rapid isometric handgrip pulses to 20-60% of their maximal voluntary contraction force while EMG was collected from the grip flexors and extensors. Dependent variables included the time to 90% peak force, the peak rate of force development, the duration above 90% of peak force, the number of segments in the force-time curve, the number of EMG bursts, time to relaxation from 90% of peak force, and the peak rate of force relaxation. People with PD had longer durations and lower rates of force change than young and older adults. Six of 22 people with PD had motor segmentation. People with PD had more EMG bursts compared to healthy adults and the number of EMG bursts covaried with the number of segments. Thus, control of rapid movement in Parkinson's disease can be studied using isometric handgrip. People with PD have impaired rate control compared to healthy adults and motor segmentation can be studied in handgrip.

Short term effects of contralateral tendon vibration on motor unit discharge rate variability and force steadiness in people with Parkinson's disease

Background

Vibration of one limb affects motor performance of the contralateral limb, and this may have clinical implications for people with lateralized motor impairments through vibration-induced increase in cortical activation, descending neural drive, or spinal excitability.

Objective

The objective of this study was to evaluate the effects of acute biceps brachii tendon vibration on force steadiness and motor unit activity in the contralateral limb of persons with Parkinson's disease.

Methods

Ten participants with mild to moderate Parkinson's disease severity performed a ramp, hold and de-ramp isometric elbow flexion at 5% of maximum voluntary contraction with the more-affected arm while vibration was applied to the distal biceps brachii tendon on the contralateral, less-affected arm. Using intramuscular fine wire electrodes, 33 MUs in the biceps brachii were recorded across three conditions (baseline, vibration, and post-vibration). Motor unit recruitment & derecruitment thresholds, discharge rates & variability, and elbow flexion force steadiness were compared between conditions with and without vibration.

Results

Coefficient of variation of force and discharge rate variability decreased 37 and 17%, respectively in post-vibration compared with baseline and vibration conditions. Although the motor unit discharge rates did not differ between conditions the total number of motor units active at rest after de-ramp were fewer in the post-vibration condition.

Conclusion

Contralateral tendon vibration reduces MU discharge rate variability and enhances force control on the more affected side in persons with Parkinson's disease.

Evaluation of putamen area and cerebral peduncle with surrounding cistern in patients with Parkinson's disease: is there a difference from controls in cranial MRI?

OBJECTIVES

Nigrostriatal dopaminergic neuron loss is essential in pathogenesis of Parkinson's disease (PD). The purpose of this study was to evaluate nigrostriatal structures including the putamen, cerebral peduncle, widths of interpeduncular cistern, and ambient cistern around the midbrain with conventional cranial magnetic resonance images (MRI) in patients with PD.

METHODS

The MRI of 56 subjects was included, which was selected from the radiological data system for this retrospective study. The 29 patients with idiopathic PD were included and their disease duration, Hoehn&Yahr stage, and Levodopa equivalent dose (LED) were recorded. The 27 controls had a normal neurologic examination and cranial MRI. All subjects in the patient and control groups had right-hand dominance. Putamen and cerebral peduncle areas and widths of interpeduncular and ambient cisterns were measured in T2 sequences of MRI. Further statistical analysis was applied to exclude gender and age effect on areas.

RESULTS

The areas of putamen and cerebral peduncles were significantly reduced in patients with PD compared to the control bilaterally (p < 0.001). Enlargement of interpeduncular and ambient cisterns in patients was higher than in controls, and it was significant (p < 0.001). A correlation was not observed between measurement results and clinical characteristics of patients with PD. Only the cerebral peduncle area/ambient cistern width ratio was significantly correlated with disease duration positively (right r = 0.46 p = 0.012, left r = 0.389 p = 0.037).

CONCLUSION

Clinicians should be careful with conventional MRIs of patients with idiopathic PD in practice. It may be different from controls without any neurological disorder, particularly putamen, cerebral peduncles, interpeduncular, and ambient cisterns.

Novel characteristics of the temporal transition to maximum tongue pressure in Parkinson's disease: A pilot study

Introduction

The reason why maximum tongue pressure (MTP) decreases in patients with Parkinson's disease (PD) remains unclear. Repeated measurements of isometric force and MTP may be useful for analyzing muscle wasting and force generation. The purpose of this pilot study was to evaluate the clinical characteristics and temporal transition of MTP in PD and normal control (NC) groups.

Methods

There were 18 participants in this study: 10 with PD and 8 NCs. The MTP was measured 20 times at regular intervals. The area under the curve of MTP temporal transitions, time to reach MTP, and total transition time of the tongue pressure (time to return to baseline) were compared between the groups.

Results

MTP decreased from baseline in PD subjects. Unlike NCs, PD subjects showed diverse and inconsistent temporal transitions. The decrease in MTP and delays in time to reach MTP and time to return to baseline were significantly greater in PD subjects (p < 0.05), while there was no group difference in area under the curve values. According to repeated-measures ANOVA, MTP was not different over time between PD subjects and NCs.

Conclusion

In this study, muscle fatigue did not affect the decrease in MTP seen in PD subjects, or the diversity and inconsistency of the temporal transition in MTP in that group. These findings indicate that the motor control needed for the repeated, identical movements associated with MTP generation may be impaired in PD patients.

Is Handgrip Strength Associated With Parkinson's Disease? Longitudinal Study of 71 702 Older Adults

BACKGROUND

To date, no study has longitudinally assessed the dose-response association between handgrip strength and incidence of Parkinson's Disease (PD).

OBJECTIVES

to investigate the longitudinal association between handgrip strength and the development of PD within a representative European population of older adults.

METHODS

Individuals aged 50 years and older from 27 European countries and Israel participated. We retrieved data from the Survey of Health, Ageing and Retirement in Europe waves 1, 2, 4, 5, 6, 7, and 8. Handgrip strength was measured using a hand dynamometer and participants reported whether they had a medical PD diagnosis. Time-varying exposure and covariates were modeled using both Cox regression and restricted cubic splines.

RESULTS

A total of 71 702 participants (mean age 65.2 years) were followed over a median period of 5.0 years. Among them, 314 participants developed PD. In the fully adjusted model, we observed a higher risk (hazard ratio [HR]: 2.50; 95% CI:1.92-3.32) of PD for participants with lower handgrip strength (third 1) and a lower risk of PD for participants in the second third (HR: 1.41; 95% CI: 1.06-1.87). In dose-response analyses, men showed lower risk of PD from 27 kg (HR:0.94; 95% CI: 0.91-0.97) to 59 kg (HR:0.10; 95% CI: 0.04-0.22), whereas women showed significant reductions from 24 kg (HR:0.68; 95% CI: 0.46-0.99) to 38 kg (HR:0.44; 95% CI: 0.22-0.88).

CONCLUSIONS

Handgrip strength ought to be incorporated as one of the measures in the prognostic toolbox for the screening of older adults who are possibly at risk of developing PD.

Moving, fast and slow: behavioural insights into bradykinesia in Parkinson's disease

The debilitating symptoms of Parkinson's disease, including the hallmark slowness of movement, termed bradykinesia, were described more than 100 years ago. Despite significant advances in elucidating the genetic, molecular and neurobiological changes in Parkinson's disease, it remains conceptually unclear exactly why patients with Parkinson's disease move slowly. To address this, we summarize behavioural observations of movement slowness in Parkinson's disease and discuss these findings in a behavioural framework of optimal control. In this framework, agents optimize the time it takes to gather and harvest rewards by adapting their movement vigour according to the reward that is at stake and the effort that needs to be expended. Thus, slow movements can be favourable when the reward is deemed unappealing or the movement very costly. While reduced reward sensitivity, which makes patients less inclined to work for reward, has been reported in Parkinson's disease, this appears to be related mainly to motivational deficits (apathy) rather than bradykinesia. Increased effort sensitivity has been proposed to underlie movement slowness in Parkinson's disease. However, careful behavioural observations of bradykinesia are inconsistent with abnormal computations of effort costs due to accuracy constraints or movement energetic expenditure. These inconsistencies can be resolved when considering that a general disability to switch between stable and dynamic movement states can contribute to an abnormal composite effort cost related to movement in Parkinson's disease. This can account for paradoxical observations such as the abnormally slow relaxation of isometric contractions or difficulties in halting a movement in Parkinson's disease, both of which increase movement energy expenditure. A sound understanding of the abnormal behavioural computations mediating motor impairment in Parkinson's disease will be vital for linking them to their underlying neural dynamics in distributed brain networks and for grounding future experimental studies in well-defined behavioural frameworks.

Use of a physiological profile to document upper limb motor impairment in ageing and in neurological conditions

Profiling performance in the physiological domains underpinning upper limb function (such as strength, sensation, coordination) provides insight into an individual's specific impairments. This compliments the traditional medical 'diagnosis' model that is currently used in contemporary medicine. From an initial battery of 13 tests in which data were collected across the adult lifespan (n = 367, 20-95 years) and in those with neurological conditions (specifically, multiple sclerosis (n = 40), Parkinson's disease (n = 34), and stroke (n = 50)), six tests were selected to comprise a core upper limb physiological profile assessment (PPA). This comprised measures of handgrip strength, simple reaction time, finger dexterity, tactile sensation, bimanual coordination, and a functional task. Individual performance in each of these tests can be compared to a reference population score (devised from our database of healthy individuals aged under 60 years), informing the researcher or clinician how to best direct an intervention or treatment for the individual based on their specific impairment(s). Lastly, a composite score calculated from the average performance across the six tests provides a broad overview of an individual's overall upper limb function. Collectively, the upper limb PPA highlights specific impairments that are prevalent within distinct pathologies and reveals the magnitude of upper limb motor impairment specific to each condition.

Rate control deficits during pinch grip and ankle dorsiflexion in early-stage Parkinson's disease

BACKGROUND

Much of our understanding of the deficits in force control in Parkinson's disease (PD) relies on findings in the upper extremity. Currently, there is a paucity of data pertaining to the effect of PD on lower limb force control.

OBJECTIVE

The purpose of this study was to concurrently evaluate upper- and lower-limb force control in early-stage PD and a group of age- and gender-matched healthy controls.

METHODS

Twenty individuals with PD and twenty-one healthy older adults participated in this study. Participants performed two visually guided, submaximal (15% of maximum voluntary contractions) isometric force tasks: a pinch grip task and an ankle dorsiflexion task. PD were tested on their more affected side and after overnight withdrawal from antiparkinsonian medication. The tested side in controls was randomized. Differences in force control capacity were assessed by manipulating speed-based and variability-based task parameters.

RESULTS

Compared with controls, PD demonstrated slower rates of force development and force relaxation during the foot task, and a slower rate of relaxation during the hand task. Force variability was similar across groups but greater in the foot than in the hand in both PD and controls. Lower limb rate control deficits were greater in PD with more severe symptoms based on the Hoehn and Yahr stage.

CONCLUSIONS

Together, these results provide quantitative evidence of an impaired capacity in PD to produce submaximal and rapid force across multiple effectors. Moreover, results suggest that force control deficits in the lower limb may become more severe with disease progression.

Screening Tools for Sarcopenia in Mild to Moderate Parkinson's Disease: Assessing the Accuracy of SARC-F and Calf Circumference

BACKGROUND

Parkinson's disease (PD) and sarcopenia share similar pathophysiological mechanisms.

OBJECTIVE

Estimate the prevalence of sarcopenia in PD patients and describe clinical and demographic features associated with sarcopenia.

METHODS

A cross-sectional study was carried out at a tertiary public hospital in Brazil. A modified HY scale of stage 1 to 3, being at least 40 years old and having the ability to stand and walk unassisted were required for eligibility. We evaluated physical performance and muscle mass using DEXA.

RESULTS

The study population comprised 124 patients, of which 53 (42.7%) were women. The mean age and mean disease duration were 65.8±10.5 and 10.1±5.8 years, respectively. The mean handgrip strength of 20.4±6.9 in woman and 34.6±8.4 kg in men. Moreover, 50.8% patients had positive SARC-F, 20% patients had probable sarcopenia, 9.6% confirmed sarcopenia, and 16.8% patients showed low muscle mass quantity measured by DEXA. Lower Levodopa Equivalent Dosage (LED) and calf circumference (CC) were independently associated with confirmed sarcopenia. LLED, higher MDS-UPDRS Part III, and lower MMSE scores were independently associated with probable sarcopenia. The CC demonstrated accuracy to identify PD patients with confirmed sarcopenia with a cut-off of <31 cm in women and <34 cm in men.

CONCLUSION

We found low prevalence of confirmed sarcopenia among PD patients. We propose that healthcare providers introduce measuring CC, which is a quick and inexpensive method to assess for sarcopenia in PD patients.

Objective and self-perceived lower limb weakness in Parkinson's disease

BACKGROUND

Lower limb weakness is a long-recognized symptom in patients with Parkinson's disease (PD), described by James Parkinson in his seminal report on 'paralysis agitans'. However, little is known on the frequency, clinical correlations, and association with objective decrease in muscle strength in such patients.

OBJECTIVE

The objective of this study was to assess the frequency of objective and perceived lower limb weakness in patients with PD.

METHODS

We studied 90 consecutive patients with PD and 52 age-matched controls. We recorded clinical and demographic variables, as well as perceived weakness and allied abnormal lower limb sensations, including 'heavy legs', 'fatigued legs', and 'pain'. Symptoms consistent with restless legs syndrome were not considered. Lower limb strength was determined in both legs by means of the Medical Research Council scale, dynamometric (leg flexion) and weighting machine (leg pressure) measures.

RESULTS

Weakness and allied abnormal lower limb sensations were reported in 69% of patients with PD and 21% of healthy controls. Patients with PD had decreased leg pressure compared with healthy controls (p = 0.002). Among patients with PD, an association between perceived leg weakness (and allied sensations) and gait freezing (p = 0.001) was observed in the multivariate regression analysis; however, these variables only explained 30.4% of the variance. Moreover, PD patients with and without abnormal lower limb sensations had similar muscle strength by objective measurements.

CONCLUSION

Perceived lower limb weakness and allied abnormal sensations are common in patients with PD. However, there is a dissociation between perceived weakness and objective muscle strength in the lower limbs. These abnormal sensations were mostly related to gait freezing but a causal association is questionable.

Impaired Ability to Relax Pelvic Floor Muscles in Men With Chronic Prostatitis/Chronic Pelvic Pain Syndrome

OBJECTIVE

Excessive pelvic floor muscle activity has been suggested as a source of pain in chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). Our objective was to determine whether men with CP/CPPS have changes in neural drive that impair their ability to relax pelvic floor muscles.

METHODS

We recruited 90 men (42 with CP/CPPS and 48 in the control group [without a history of pelvic pain]). All completed the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI). We quantified the ability to relax by comparing resting pelvic floor muscle activity under 2 conditions: a "rest-only" condition, in which participants were instructed to simply relax, and a "rest-between-contraction" condition, in which participants were instructed to rest for several seconds between voluntary pelvic floor muscle contractions. We used multivariate mixed-effects models to examine differences between the groups (men with CP/CPPS and men in the control group) as well as the effect of 6 symptoms captured by the NIH-CPSI: pain related to location (perineum, testicles, penis, suprapubic region) and activity (urination, ejaculation).

RESULTS

Men with CP/CPPS were significantly different from men in the control group; men with CP/CPPS had higher resting activity in the rest-between-contraction condition than in the rest-only condition, whereas men in the control group had similar resting activities in both conditions. This effect was strongest in men who reported ejaculation-related pain, which was 70% of the CP/CPPS group.

CONCLUSION

Men without a history of pelvic pain were able to relax their pelvic floor muscles back to baseline after performing voluntary pelvic floor muscle contractions. In contrast, men with CP/CPPS, particularly those with ejaculation-related pain, had an impaired ability to relax their pelvic floor muscles.

IMPACT

This study may support the investigation of more personalized physical therapist approaches for CP/CPPS that enhance the ability to relax pelvic floor muscles as a mechanism for pain reduction.

Can People with Parkinson's Disease Self-Trigger Gait Initiation? A Comparison of Cueing Strategies

BACKGROUND

An external cue can markedly improve gait initiation in people with Parkinson's disease (PD) and is often used to overcome freezing of gait (FOG). It is unknown if the effects of external cueing are comparable if the imperative stimulus is triggered by the person receiving the cue (self-triggered) or an external source.

OBJECTIVE

Two experiments were conducted to compare the effects of self- versus externally triggered cueing on anticipatory postural adjustments (APAs) during gait initiation in people with PD.

METHODS

In experiment 1, 10 individuals with PD and FOG initiated gait without a cue or in response to a stimulus triggered by the experimenter or by the participant. Experiment 2 compared self- versus externally triggered cueing across three groups: healthy young adults (n = 16), healthy older adults (n = 11), and a group with PD (n = 10).

RESULTS

Experiment 1: Externally triggered cues significantly increased APA magnitudes compared to uncued stepping, but not when the same cue was self-triggered. Experiment 2: APAs were not significantly improved with a self-triggered cue compared to un-cued stepping in both the PD and healthy older adult groups, but the young adults showed a significant facilitation of APA magnitude.

CONCLUSION

The effectiveness of an external cue on gait initiation in people with PD and older adults is critically dependent upon whether the source of the trigger is endogenous (self-produced) or exogenous (externally-generated). These results may explain why cueing interventions that rely upon self-triggering of the stimulus are often ineffective in people with PD.

Reaching and Grasping Movements in Parkinson's Disease: A Review

Parkinson's disease (PD) is known to affect the brain motor circuits involving the basal ganglia (BG) and to induce, among other signs, general slowness and paucity of movements. In upper limb movements, PD patients show a systematic prolongation of movement duration while maintaining a sufficient level of endpoint accuracy. PD appears to cause impairments not only in movement execution, but also in movement initiation and planning, as revealed by abnormal preparatory activity of motor-related brain areas. Grasping movement is affected as well, particularly in the coordination of the hand aperture with the transport phase. In the last fifty years, numerous behavioral studies attempted to clarify the mechanisms underlying these anomalies, speculating on the plausible role that the BG-thalamo-cortical circuitry may play in normal and pathological motor control. Still, many questions remain open, especially concerning the management of the speed-accuracy tradeoff and the online feedback control. In this review, we summarize the literature results on reaching and grasping in parkinsonian patients. We analyze the relevant hypotheses on the origins of dysfunction, by focusing on the motor control aspects involved in the different movement phases and the corresponding role played by the BG. We conclude with an insight into the innovative stimulation techniques and computational models recently proposed, which might be helpful in further clarifying the mechanisms through which PD affects reaching and grasping movements.

Clinical features contributing to the sit-to-stand transfer in people with Parkinson’s disease: a systematic review

Introduction

The aim of this systematic review is to present the existing literature on the clinical motor, and non-motor factors contributing to sit-to-stand transfer in individuals with Parkinson's disease.

Data synthesis

Five databases (PubMed, PEDro, Cochrane, SCOPUS, and Ovid) were searched for literature on the contributing factors to sit-to-stand performance in Parkinson's disease. A quality check of these observational studies was done using the 'strengthening the reporting of observational studies in epidemiology' (STROBE) statement and the tool of the 'National Heart, Lung, and Blood Institute' (NHLBI). Descriptive and quantitative data were extracted and compiled, and a meta-analysis was performed to compute the standardised mean difference.

Results

Thirteen studies were selected; a majority of them provided a high-to-moderate level of evidence. Ten were cross-sectional, while the other three were case–control studies. Collectively, individuals with Parkinson's disease had a prolonged transfer time than those of age-matched healthy peers, particularly from peak horizontal velocity phase to seat-off phase, implying bradykinesia. A reduction in peak and rate to peak joint torques was also related to the decreased pace and stability of the sit-to-stand movement in individuals with Parkinson's disease. Additionally, they demonstrated exaggerated trunk flexion as a postural stabilisation strategy, allowing them to maintain and manoeuvre the relative positions of their centre of mass through the transitional phase of the transfer.

Conclusion

As per the existing literature, an alteration in strength, overall body bradykinesia, balance, posture, as well as cognition may result in an impaired sit-to-stand transfer in individuals with Parkinson's disease.

Influence of muscle fatigue on contractile twitch characteristics in persons with parkinson's disease and older adults: A pilot study

Introduction

It is widely accepted that pathophysiological changes to the central nervous system of persons with Parkinson's disease (PD) result in negative effects on motor function. However, less information is known regarding the pathology of PD on skeletal muscle. The purpose of this study was to determine the effect of a fatiguing isometric knee extension protocol on muscle mechanics using evoked twitch contractions in persons with PD and in non-impaired older adults (OLD).

Methods

Evoked twitch contractions were examined during a fatiguing protocol in PD (66 ± 9 yr, n = 8) and OLD (65 ± 10 yr, n = 5). Participants performed 5-sec maximal isometric voluntary contractions of the quadriceps femoris with 5-sec rest for 3-min. Every 30-sec during rest intervals, a maximal transcutaneous electrical stimulus was administered to the quadriceps femoris to quantify evoked peak twitch torque (pTT), peak relaxation rate (pRR), and peak rate of torque development (pRTD).

Results

A large effect of voluntary fatigue (%decline) was observed (g = 1.58). There were no significant differences in pTT (p = 0.09; 95% CI:-3.6, 0.28) or pRR (p = 0.11; 95% CI:-31, 3.6). However, the slope decline of pRTD in OLD (-35.4 ± 24.7) was greater than PD (-11.5 ± 11.4; p = 0.03), indicating that skeletal muscle in persons with PD is less fatigable compared to non-impaired older adults.

Conclusion

The rate, not the maximum capacity, of torque generation of the muscle during a fatiguing knee extension protocol was affected by PD. Future studies are warranted to identify the mechanism(s) responsible for the observed differences in skeletal muscle contractile characteristics and potential myofiber distribution variation in PD.

Parkinson's disease and multicomponent aquatic exercise: Effects on motor aspects, functional mobility, muscle function and aquatic motor skills

OBJECTIVE

Analyze the effects of a multicomponent aquatic exercise program on motor aspects, functional mobility, muscle function and aquatic motor skills of people with PD.

METHODS

Eighteen people with a PD diagnosis were assessed before and after a 12-week multicomponent aquatic exercise program, twice a week, with each session lasting 50 min. The terrestrial variables analyzed were motor aspects, through the Unified Parkinson Disease Rating Scale (UPDRS); functional mobility, through the Five Times Sit to Stand Test (FTSST); Peak Torque (PT) and Mean Power (MP) of hip, knee and ankle flexors and extensors, assessed using an isokinetic dynamometer. In water, aquatic motor skill levels were assessed by means of the Aquatic Functional Assessment Scale (AFAS).

RESULTS

Significant improvements were found after the intervention in the following outcomes: motor aspects (p = 0.038, Δ = 5-61); MP of knee flexors at 90°/s on the most affected side (p = 0.026, Δ = 5.14), MP of knee extensors at 90°/s on the most affected side (p = 0.008, Δ = 8.69), MP of knee extensors at 120°/s on the most affected side (p = 0.005, Δ = 8.35), and AFAS in the domain of specialized therapeutic exercises (p = 0.014, Δ = 1.28).

CONCLUSIONS

The completed multicomponent aquatic exercise program promoted changes in muscle function and terrestrial and aquatic functional outcomes in people with PD.

Quantifying upper limb motor impairment in people with Parkinson's disease: a physiological profiling approach

BACKGROUND

Upper limb motor impairments, such as slowness of movement and difficulties executing sequential tasks, are common in people with Parkinson's disease (PD).

OBJECTIVE

To evaluate the validity of the upper limb Physiological Profile Assessment (PPA) as a standard clinical assessment battery in people with PD, by determining whether the tests, which encompass muscle strength, dexterity, arm stability, position sense, skin sensation and bimanual coordination can (a) distinguish people with PD from healthy controls, (b) detect differences in upper limb test domains between "off" and "on" anti-Parkinson medication states and (c) correlate with a validated measure of upper limb function.

METHODS

Thirty-four participants with PD and 68 healthy controls completed the upper limb PPA tests within a single session.

RESULTS

People with PD exhibited impaired performance across most test domains. Based on validity, reliability and feasibility, six tests (handgrip strength, finger-press reaction time, 9-hole peg test, bimanual pole test, arm stability, and shirt buttoning) were identified as key tests for the assessment of upper limb function in people with PD.

CONCLUSIONS

The upper limb PPA provides a valid, quick and simple means of quantifying specific upper limb impairments in people with PD. These findings indicate clinical assessments should prioritise tests of muscle strength, unilateral movement and dexterity, bimanual coordination, arm stability and functional tasks in people with PD as these domains are the most commonly and significantly impaired.

People with mild PD have impaired force production in all lower limb muscle groups: A cross-sectional study

BACKGROUND

Power is reduced in people with Parkinson's disease as a consequence of bradykinesia, but it is not clear whether reduced power is also due to a deficit in force production. The aim of this study was to quantify force production in all major lower limb muscle groups in people with PD during the "on" phase after medication, compared with aged-matched neurologically normal control participants.

METHOD

Design: A cross-sectional study was undertaken.

PARTICIPANTS

Thirty ambulatory people with PD and 24 neurologically normal controls.

OUTCOME MEASURES

Isometric force production of the hip flexors and extensors, hip adductors and abductors, hip internal rotators and external rotators, knee flexors and extensors, ankle dorsiflexors and plantarflexors, ankle invertors and evertors using hand-held dynamometry.

RESULTS

There was a significant deficit in force production in participants with PD in all lower limb muscle groups tested, compared with control participants. On average, force production of participants with PD was 78% (range 67%-87%) of control participants, despite participants with PD regularly participating in exercise, being measured during their "on" phase after medication and having normal walking ability. The most severely affected muscle groups were the hip adductors (67%) and ankle plantarflexors (68%).

CONCLUSION

People with PD have a significant loss of force production in all lower limb muscle groups compared with age-matched neurologically-normal controls.

IMPLICATIONS FOR PHYSIOTHERAPY PRACTICE

Clinicians should regularly assess the strength of all lower limb muscle groups, regardless of participation in physical activity, responsiveness to levodopa medication and walking ability.

Voluntary Muscle Relaxation Can Mitigate Fatigue and Improve Countermovement Jump Performance

Pinto, BL and McGill, SM. Voluntary muscle relaxation can mitigate fatigue and improve countermovement jump performance. J Strength Cond Res 34(6): 1525-1529, 2020-When muscles contract, they create force and stiffness. Thus, muscle activation and relaxation must be strategically sequenced to coordinate and control movement, to enhance athletic variables such as speed and strength. However, research has favored investigation of muscle activation over relaxation. Athletes such as runners, swimmers, and boxers often shake their limbs to allow the muscle to oscillate freely, immediately before a bout. The purpose was to investigate whether shaking the lower limbs with the intention to voluntarily relax the muscles of the limb has an effect on countermovement jump (CMJ) performance. Subjects performed 10 maximal effort CMJs with 30 seconds of rest between each jump. During the rest period, they either performed the relaxation technique or control condition (standing still). Statistical significance was considered at p < 0.05. Subjects significantly improved jump height, compared with their first jump of the day, when performing the relaxation technique. To further investigate the mechanism of enhancement, subjects were grouped into responders and nonresponders. The responder group significantly decreased their jump height and concentric phase impulse (relative to the first jump) during the control condition compared with the nonresponder group, indicating fatigue. When performing the relaxation technique, the responder group improved their jump height and mitigated fatigue by significantly increasing their unweighting impulse and unweighting force. The relaxation technique improved CMJ performance, specifically in those that fatigue with consecutive bouts, by enhancing unweighting, that requires muscle relaxation, rather than propulsion that requires activation. This technique can be useful for training or competition.

Progressive muscle-strength protocol for the functionality of upper limbs and quality of life in individuals with Parkinson's disease: Pilot study

The effects of physical-therapy intervention on the motor function of upper limbs and the quality of life in patients with Parkinson's disease (PD) are not fully understood. We evaluated the effects of a progressive muscle-strengthening protocol for upper limbs on the functionality and quality of life. Patients were divided into two groups: Intervention (n = 6) and Control (n = 7). Assessment tools used were: Unified Parkinson's Disease Rating Scale (UPDRS), Parkinson's Disease Questionnaire, Nine-Hole Peg Test (9HPT), Test d'Évaluation des Membres Supérieurs de Personnes Âgées (TEMPA), 10-Repetition Maximum (10-RM) and handgrip dynamometer, which were applied pre- and post-intervention, with follow-up for one month after the last training session. Only, the Intervention group (post-intervention) showed significant statistical differences, with the following outcomes: UPDRS III (p = 0.042); 9HPT, right (p = 0.028) and left side (p = 0.028); TEMPA for total right side (p = 0.028), left side (p = 0.028) and total bilateral tasks (p = 0.028); TEMPA task 2 - open a jar and take a spoonful of coffee (p = 0.028), task 3 - pick up a pitcher and pour water into a glass for right (p = 0.046) and left side (p = 0.028), task 5 - write on an envelope and stick on a stamp (p = 0.028), and task 6 - shuffle and deal playing cards (p = 0.028). We observed significant statistical differences between groups (post-intervention) for TEMPA task 6 (p = 0.032), total right side (p = 0.032), and total bilateral tasks (p = 0.032). An increase in the maximum load in the post-intervention stage, based on the 10-RM test, was observed on the right (p = 0.003) and left (p = 0.007) sides. Our results showed an improvement in upper-limb functionality in PD patients submitted to progressive muscle-strength training, although not in quality of life.

Motor Unit Discharge Variability Is Increased in Mild-To-Moderate Parkinson's Disease

Individuals with Parkinson's disease (PD) demonstrate deficits in muscle activation such as decreased amplitude and inappropriate bursting. There is evidence that some of these disturbances are more pronounced in extensor vs. flexor muscles. Surface EMG has been used widely to quantify muscle activation deficits in PD, but analysis of discharge of the underlying motor units may provide greater insight and be more sensitive to changes early in the disease. Of the few studies that have examined motor unit discharge in PD, the majority were conducted in the first dorsal interosseous, and no studies have measured motor units from extensor and flexor muscles within the same cohort. The objective of this study was to characterize the firing behavior of single motor units in the elbow flexor and extensor muscles during isometric contractions in people with mild-to-moderate PD. Ten individuals with PD (off-medication) and nine healthy controls were tested. Motor unit spike times were recorded via intramuscular EMG from the biceps and triceps brachii muscles during 30-s isometric contractions at 10% maximum voluntary elbow flexion and elbow extension torque, respectively. We selected variables of mean motor unit discharge rate, discharge variability, and torque variability to evaluate motor abnormalities in the PD group. The effects of group, muscle, and group-by-muscle on each variable were determined using separate linear mixed models. Discharge rate and torque variability were not different between groups, but discharge variability was significantly higher in the PD group for both muscles combined (p < 0.0001). We also evaluated the asymmetry in these motor variables between the triceps and biceps for each individual participant with PD to evaluate whether there was an association with disease severity. The difference in torque variability between elbow flexion and extension was significantly correlated with both the Hoehn and Yahr scale (rho = 0.71) and UPDRS (rho = 0.62). Our findings demonstrate that variability in motor output, rather than decreased discharge rates, may contribute to motor dysfunction in people with mild-to-moderate PD. Our findings provide insight into altered neural control of movement in PD and demonstrate the importance of measuring from multiple muscles within the same cohort.

Evolving concepts on bradykinesia

Bradykinesia is one of the cardinal motor symptoms of Parkinson's disease and other parkinsonisms. The various clinical aspects related to bradykinesia and the pathophysiological mechanisms underlying bradykinesia are, however, still unclear. In this article, we review clinical and experimental studies on bradykinesia performed in patients with Parkinson's disease and atypical parkinsonism. We also review studies on animal experiments dealing with pathophysiological aspects of the parkinsonian state. In Parkinson's disease, bradykinesia is characterized by slowness, the reduced amplitude of movement, and sequence effect. These features are also present in atypical parkinsonisms, but the sequence effect is not common. Levodopa therapy improves bradykinesia, but treatment variably affects the bradykinesia features and does not significantly modify the sequence effect. Findings from animal and patients demonstrate the role of the basal ganglia and other interconnected structures, such as the primary motor cortex and cerebellum, as well as the contribution of abnormal sensorimotor processing. Bradykinesia should be interpreted as arising from network dysfunction. A better understanding of bradykinesia pathophysiology will serve as the new starting point for clinical and experimental purposes.

Progressive Resistance Training Improves Bradykinesia, Motor Symptoms and Functional Performance in Patients with Parkinson's Disease

Purpose

Bradykinesia and muscle weaknesses are common symptoms of Parkinson’s Disease (PD) and are associated with impaired functional performance, increased risk of falls, and reduced quality of life. Recent studies have pointed to progressive resistance training (PRT) as an effective method to control and reduce these symptoms, increasing possibilities to treat the disease. However, few studies have focused on assessing the PRT effects in the short-term. Therefore, the present study aimed to assess the short-term PRT effects on people with PD, in order to offer new parameters for a better understanding of its effects, so as an adequation and PRT use as a complementary therapy.

Patients and Methods

Forty individuals diagnosed with PD from stage 1 to 3 on the Hoehn and Yahr scale took part on the study and were allocated into 2 groups; Training Group (TG) performed a 9-week RT program twice a week, and the Control Group (CG) attended disease lectures. Bradykinesia UPDRS subscale (BSS), knee extensors isokinetic strength, Ten Meters Walk Test (TMW), Timed Up&Go Test (TUG) and 30-Second Chair Stand (T30) were measured before and after the intervention period. Statistical significance was set at p ≤ 0.05.

Results

Significant time was noted by the group interaction for all functional tests (TUG, T30, and TWM; all p < 0.01) and BSS (p < 0.01). Post hoc analyses revealed that these differences were driven by significant improvements in these dependent variables (all p < 0.01) while the CG remained unchanged (all p > 0.05). Moreover, TUG, T30, TWM, and BSS were significantly different between TG and CG in the post-training assessments (all p < 0.01). Isokinetic muscle strength was slightly increased in the TG (2.4%) and decreased in the CG (−2.2%), but statistical analyses did not reach significance for interaction but only a trend (p = 0.12).

Conclusion

The results indicate that 9 weeks of PRT reduces bradykinesia and improves functional performance in patients with mild to moderate PD. These findings reinforce this mode of exercise as an important component of public health promotion programs for PD.

Association between strength with day sleepiness in individuals with Parkinson’s disease

Abstract The aim of this study is to analyze if there is an association between excessive daytime sleepiness with muscle strength in people with Parkinson’s disease. This study is a cross-sectional study, with a quantitative approach. A total of 29 individuals with Parkinson’s disease were recruited and classified in one of four stages of the modified Hoehn and Yahr scale. To assess the excessive daytime sleepiness the Epworth Sleepiness scale was used. The muscle strength was assess with handgrip and isokinetic dynamometers. There are non-significant correlation between Epworth Sleepiness scale with muscle strength, p < 0.05 and rho < 0.3. The muscle strength assessed by handgrip and isokinetic dynamometers does not associated with excessive daytime sleepiness assessed by Epworth Sleepiness scale.

Levodopa Modulates Functional Connectivity in the Upper Beta Band Between Subthalamic Nucleus and Muscle Activity in Tonic and Phasic Motor Activity Patterns in Parkinson's Disease

Introduction: Striatal dopamine depletion disrupts basal ganglia function and causes Parkinson's disease (PD). The pathophysiology of the dopamine-dependent relationship between basal ganglia signaling and motor control, however, is not fully understood. We obtained simultaneous recordings of local field potentials (LFPs) from the subthalamic nucleus (STN) and electromyograms (EMGs) in patients with PD to investigate the impact of dopaminergic state and movement on long-range beta functional connectivity between basal ganglia and lower motor neurons. Methods: Eight PD patients were investigated 3 months after implantation of a deep brain stimulation (DBS)-system capable of recording LFPs via chronically-implanted leads (Medtronic, ACTIVA PC+S^®). We analyzed STN spectral power and its coherence with EMG in the context of two different movement paradigms (tonic wrist extension vs. alternating wrist extension and flexion) and the effect of levodopa (L-Dopa) intake using an unbiased data-driven approach to determine regions of interest (ROI). Results: Two ROIs capturing prominent coherence within a grand average coherogram were identified. A trend of a dopamine effect was observed for the first ROI (50-150 ms after movement start) with higher STN-EMG coherence in medicated patients. Concerning the second ROI (300-500 ms after movement start), an interaction effect of L-Dopa medication and movement task was observed with higher coherence in the isometric contraction task compared to alternating movements in the medication ON state, a pattern which was reversed in L-Dopa OFF. Discussion: L-Dopa medication may normalize functional connectivity between remote structures of the motor system with increased upper beta coherence reflecting a physiological restriction of the amount of information conveyed between remote structures. This may be necessary to maintain simple movements like isometric contraction. Our study adds dynamic properties to the complex interplay between STN spectral beta power and the nucleus' functional connectivity to remote structures of the motor system as a function of movement and dopaminergic state. This may help to identify markers of neuronal activity relevant for more individualized programming of DBS therapy.

Spinal motor neurons and motor function in older adults

This study examined the relation between lumbar spinal motor neuron (SMN) indices and motor function proximate to death in community-dwelling older adults. Older adults (N = 145) participating in the Rush Memory and Aging Project underwent structured clinical testing proximate to death and brain and spinal cord autopsy at time of death. Ten motor performances were summarized by a composite global motor score. Choline acetyltransferase immunostaining was used to identify spinal motor neurons of the L4/5 segment. SMN counts and area and ventral horn area were collected. Linear regression modeling showed that the association of SMN counts and density with global motor scores proximate to death varied with sex. Separate models in men and women showed that this significant interaction was due to the association of higher SMN counts and density with higher global motor scores proximate to death in men but not women. These associations were unchanged when we controlled for indices of brain pathologies or chronic health conditions. In 38 cases with counts of activated microglia available, higher counts of activated microglia were associated with lower SMN counts. Activated spinal microglia and loss of spinal motor neurons may contribute to motor impairments in older men.

Association of Strength and Physical Functions in People with Parkinson's Disease

Background

Parkinson's disease is responsible for decrease of activities of daily living and mobility limitations. Association of strength with physical capacities and disease time can improve training methodologies and predict changes in physical fitness for this population, since the control center of movements and strength is the same.

Objective

Therefore, the aim of this study is to analyze if there are correlation between strength with functional tests (the sit-to-stand, the six-minute walk, and the timed-up-go) and disease time in people with Parkinson's disease.

Results

All functional tests correlations are significant, p < 0.05. The strength is positively correlated with the sit-to-stand and the six-minute walk. The strength is negatively correlated with the timed-up-go.

Conclusion

There are a correlation between strength with functional tests in people with PD, and changes in strength assessment can be used as predictor to changes in aerobic capacity.

The effect of medication on vastus lateralis muscle activation patterns in Parkinson's disease patients

The effect of levodopa on muscle activity patterns in Parkinson's disease (PD) patients is currently unclear. The aim of the present study was to compare the spatial distribution pattern of electromyographic activity during sustained isometric contraction in PD patients during on- and off-medication periods using multi-channel surface electromyography (SEMG). Ten female PD patients were recruited for the present study. All patients performed a sustained isometric knee extension at 10% maximum voluntary contraction task for 60 s. To evaluate alterations in the spatial SEMG potential distribution, the coefficient of variation (CV) of force, normalized root mean square (RMS), modified entropy, CV of the RMS, and correlation coefficients were calculated at during contraction task. The off-medication period exhibited more fluctuation during the contraction task than those in the on-medication period. The off-medication period exhibited less change in modified entropy, the CV of RMS, the correlation coefficient and patterns of spatial SEMG distribution. These data demonstrated that the heterogeneity and changes in the activation pattern are smaller in the off-medication period than in those in the on-medication period. These findings might indicate that levodopa enhanced the activation of muscle action potentials during force production.

An 8-Week Low-Intensity Progressive Cycling Training Improves Motor Functions in Patients with Early-Stage Parkinson's Disease

BACKGROUND AND PURPOSE

The effects of high-intensity cycling as an adjuvant therapy for early-stage Parkinson's disease (PD) were highlighted recently. However, patients experience difficulties in maintaining these cycling training programs. The present study investigated the efficacy of cycling at a mild-to-moderate intensity in early-stage PD.

METHODS

Thirteen PD patients were enrolled for 16 serial cycling sessions over a 2-month period. Motor function was assessed using the Unified Parkinson's Disease Rating Scale part III (UPDRS III) and Timed Up and Go (TUG) test as primary outcomes. The Montreal Cognitive Assessment (MoCA), modified Hoehn and Yahr Stage (mHYS), total UPDRS, Falls Efficacy Scale, New Freezing of Gait Questionnaire, Schwab and England Activities of Daily Living, 39-item Parkinson's Disease Questionnaire, Patient Global Impression of Change, and gait performance were assessed as secondary outcomes.

RESULTS

The age and the age at onset were 59.67±7.24 and 53.23±10.26 years (mean±SD), respectively. The cycling cadence was 53.27±8.92 revolutions per minute. The UPDRS III score improved significantly after 8 training sessions (p=0.011) and 16 training sessions (T2) (p=0.001) in the off-state, and at T2 (p=0.004) in the on-state compared to pretraining (T0). The TUG duration was significantly shorter at T2 than at T0 (p<0.05). The findings of MoCA, total UPDRS, double limb support time, and mHYS (in both the off- and on-states) also improved significantly at T2.

CONCLUSIONS

Our pioneer study has demonstrated that a low-intensity progressive cycling exercise can improve motor function in PD, especially akinesia. The beneficial effects were similar to those of high-intensity rehabilitation programs.

Can therapeutic Thai massage improve upper limb muscle strength in Parkinson's disease? An objective randomized-controlled trial

Muscle weakness is a frequent complaint amongst Parkinson's disease (PD) patients. However, evidence-based therapeutic options for this symptom are limited. We objectively measure the efficacy of therapeutic Thai massage (TTM) on upper limb muscle strength, using an isokinetic dynamometer. A total of 60 PD patients with muscle weakness that is not related to their ‘off’ periods or other neurological causes were equally randomized to TTM intervention (n = 30), consisting of six TTM sessions over a 3-week period, or standard medical care (no intervention, n = 30). Primary outcomes included peak extension and flexion torques. Scale-based outcomes, including Unified Parkinson's Disease Rating Scale (UPDRS) and visual analogue scale for pain (VAS) were also performed. From baseline to end of treatment, patients in the intervention group showed significant improvement on primary objective outcomes, including peak flexion torque (F = 30.613, p < .001) and peak extension torque (F = 35.569, p < .001) and time to maximal flexion speed (F = 14.216, p = .001). Scale-based assessments mirrored improvements in the objective outcomes with a significant improvement from baseline to end of treatment of the UPDRS-bradykinesia of a more affected upper limb (F = 9.239, p = .005), and VAS (F = 69.864, p < .001) following the TTM intervention, compared to the control group. No patients reported adverse events in association with TTM. Our findings provide objective evidence that TTM used in combination with standard medical therapies is effective in improving upper limb muscle strength in patients with PD. Further studies are needed to determine the efficacy of TTM on other motor and non-motor symptoms in PD.

Instability Resistance Training Improves Neuromuscular Outcome in Parkinson's Disease

PURPOSE

This study compared the effects of resistance training (RT) and RT with instability (RTI) on neuromuscular and total training volume (TTV) outcomes obtained as part of the Instability Resistance Training Trial in Parkinson's disease. It also used a linear multiple regression (forward stepwise method) to identify the contribution of neuromuscular outcomes to previously published improvements in the timed-up-and-go test and the Unified Parkinson's Disease Rating Scale, motor subscale score.

METHODS

Thirty-nine patients with moderate to severe Parkinson's disease were randomly assigned to three groups: control (C), RT, and RTI. RT and RTI groups performed resistance exercises twice a week for 12 wk, and only the RTI group used unstable devices to perform resistance exercises. The following neuromuscular outcomes were assessed: quadriceps muscle cross-sectional area, root mean square and mean spike frequency of electromyographic signal, peak torque, rate of torque development, and half relaxation time of the knee extensors and plantarflexors during maximum ballistic voluntary isometric contractions. TTV was calculated for lower limb exercises.

RESULTS

From pre- to posttraining, RTI improved all of the neuromuscular outcomes (P < 0.05) except half relaxation time of the knee extensors (P = 0.068), despite the lower TTV than RT (P < 0.05). RTI was more effective than RT in increasing the root mean square values of vastus medialis, mean spike frequency of gastrocnemius medialis, and rate of torque development of plantarflexors (P < 0.05). Stepwise regression identified the changes in mean spike frequency of gastrocnemius medialis as the best predictor of improvements in timed-up-and-go test (R = 0.58, P = 0.002) and on-medication Unified Parkinson's Disease Rating Scale, motor subscale scores (R = 0.40, P = 0.020).

CONCLUSION

RTI optimizes neuromuscular adaptations, which partially explains mobility and motor sign improvements in patients with Parkinson's disease.

A little trouble getting started: Initial slowness in Parkinson's disease step negotiation

Bradykinesia is a prominent problem for persons with Parkinson's disease (PD) and has been studied extensively with upper extremity tasks; however there is a lack of research examining bradykinesia in targeted lower extremity tasks related to mobility. Navigating steps and curbs are challenging tasks for older adults and neurologically impaired and thus utilizing these behaviors provides ecological validity to the study of bradykinesia. Herein we assess differences in step negotiation performance between individuals with PD and aged matched older adults. Three-dimensional kinematics and ground reaction forces were collected while 12 participants with PD and 12 older adults performed a single step up onto a platform. Persons with PD spent a significantly greater amount of time in the heel lift phase (P=0.0003, d=1.80). Peak vertical foot velocity of the lead foot was also significantly less in PD (P=0.02, d=1.05). Lastly, persons with PD displayed reduced sagittal hip and knee range of motion during the trail step (P=0.01, d=1.20 and P=0.02, d=1.05, respectively). Parkinson's participants exhibited slight decrement in step negotiation execution. Increased step time and decreased foot velocity and range of motion were attributes associated with Parkinson's step negotiation performance. Contrary to our hypothesis, in many comparisons, persons with PD during their best medicated state performed comparable to older adults, indicative of successful pharmacotherapy. Rehabilitation efforts can seek to improve performance in motor control tasks such as step negotiation, by restoring the relationship between perceived and actual motor output and enhancing muscle coordination and output as well as ranges of motion.

Neuromuscular rate of force development deficit in Parkinson disease

BACKGROUND

Bradykinesia and reduced neuromuscular force exist in Parkinson disease. The interpolated twitch technique has been used to evaluate central versus peripheral manifestations of neuromuscular strength in healthy, aging, and athletic populations, as well as moderate to advanced Parkinson disease, but this method has not been used in mild Parkinson disease. This study aimed to evaluate quadriceps femoris rate of force development and quantify potential central and peripheral activation deficits in individuals with Parkinson disease.

METHODS

Nine persons with mild Parkinson Disease (Hoehn & Yahr≤2, Unified Parkinson Disease Rating Scale total score=mean 19.1 (SD 5.0)) and eight age-matched controls were recruited in a cross-sectional investigation. Quadriceps femoris voluntary and stimulated maximal force and rate of force development were evaluated using the interpolated twitch technique.

FINDINGS

Thirteen participants satisfactorily completed the protocol. Individuals with early Parkinson disease (n=7) had significantly slower voluntary rate of force development (p=0.008; d=1.97) and rate of force development ratio (p=0.004; d=2.18) than controls (n=6). No significant differences were found between groups for all other variables.

INTERPRETATIONS

Persons with mild-to-moderate Parkinson disease display disparities in rate of force development, even without deficits in maximal force. The inability to produce force at a rate comparable to controls is likely a downstream effect of central dysfunction of the motor pathway in Parkinson disease.

The Phenomenology of Parkinson's Disease

The motor symptoms of Parkinson's disease are not limited to the cardinal symptoms of bradykinesia, rigidity, and resting tremor, but also include a variety of interrelated motor phenomena such as deficits in spatiotemporal planning and movement sequencing, scaling and timing of movements, and intermuscular coordination that can be clinically observed. Although many of these phenomena overlap, a review of the full breadth of the motor phenomenon can aid in the diagnosis and monitoring of disease progression.

Decoding gripping force based on local field potentials recorded from subthalamic nucleus in humans

The basal ganglia are known to be involved in the planning, execution and control of gripping force and movement vigour. Here we aim to define the nature of the basal ganglia control signal for force and to decode gripping force based on local field potential (LFP) activities recorded from the subthalamic nucleus (STN) in patients with deep brain stimulation (DBS) electrodes. We found that STN LFP activities in the gamma (55-90 Hz) and beta (13-30m Hz) bands were most informative about gripping force, and that a first order dynamic linear model with these STN LFP features as inputs can be used to decode the temporal profile of gripping force. Our results enhance the understanding of how the basal ganglia control gripping force, and also suggest that deep brain LFPs could potentially be used to decode movement parameters related to force and movement vigour for the development of advanced human-machine interfaces.

Simultaneous assessment of hand function and neuromuscular quickness through a static object manipulation task in healthy adults

Both hand function [as seen through the coordination between grip force (GF) and load force (LF)] and the ability to produce a submaximal force quickly (i.e., neuromuscular quickness) are two important qualities of motor function that could be seriously affected by the presence of neurological diseases. Therefore, their quantitative assessment is very important in clinical settings. Within this study, we aimed to develop, standardize, and measure the within-session reliability of a clinically meaningful test that assesses both hand function and neuromuscular quickness simultaneously. Thirteen healthy young adults produced around 90 rapid isometric LF pulses to varying submaximal magnitudes by either pulling down or pulling up on an externally fixed GF- and LF-measuring device. Results revealed high indices of force coordination (i.e., GF scaling as assessed by GF/LF and GF coupling as assessed by maximum cross-correlation between GF and LF) in both force directions, while GF coupling was higher in downward than in upward direction (p < 0.001). Regarding the indices of neuromuscular quickness (i.e., the regression parameters obtained from the relationship between peak force and it's rate of development and half-relaxation time), results, in general, revealed a higher slope (named as rate of force development scaling factor; p < 0.01), similar R ² (p > 0.05), and shorter half-relaxation time (p < 0.05) for LF than for GF. Furthermore, all of the selected variables showed moderate to excellent within-session reliability with only 45 pulses. Findings suggest that brief force production tasks should be further evaluated as clinical tests of hand function and neuromuscular quickness in various populations.

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

In Parkinson's 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.

Pathophysiology of Motor Dysfunction in Parkinson's Disease as the Rationale for Drug Treatment and Rehabilitation

Cardinal motor features of Parkinson's disease (PD) include bradykinesia, rest tremor, and rigidity, which appear in the early stages of the disease and largely depend on dopaminergic nigrostriatal denervation. Intermediate and advanced PD stages are characterized by motor fluctuations and dyskinesia, which depend on complex mechanisms secondary to severe nigrostriatal loss and to the problems related to oral levodopa absorption, and motor and nonmotor symptoms and signs that are secondary to marked dopaminergic loss and multisystem neurodegeneration with damage to nondopaminergic pathways. Nondopaminergic dysfunction results in motor problems, including posture, balance and gait disturbances, and fatigue, and nonmotor problems, encompassing depression, apathy, cognitive impairment, sleep disturbances, pain, and autonomic dysfunction. There are a number of symptomatic drugs for PD motor signs, but the pharmacological resources for nonmotor signs and symptoms are limited, and rehabilitation may contribute to their treatment. The present review will focus on classical notions and recent insights into the neuropathology, neuropharmacology, and neurophysiology of motor dysfunction of PD. These pieces of information represent the basis for the pharmacological, neurosurgical, and rehabilitative approaches to PD.

Execution of Activities of Daily Living in Persons with Parkinson Disease

INTRODUCTION

Muscular weakness and the motor difficulties associated with Parkinson disease (PD) often impair the performance of activities of daily living (ADL). However, little is known about the magnitude and distribution of relative muscular effort of persons with PD during ADL. The purpose of this investigation was to determine the relative magnitude of lower extremity moment production that persons with PD use to perform common ADL.

METHODS

Fifteen participants with mild-to-moderate PD and 14 age/sex-matched controls volunteered. Participants performed a series of ADL tasks, as follows: gait initiation (GI), gait, and stair ascending tasks. Participants were then asked to perform maximal-effort isokinetic tests of hip and knee extension and ankle plantarflexion at speeds of 90° per second and 120° per second. Relative effort was quantified as a percentage of the maximal isokinetic value produced by a joint during performance of the ADL. Relative effort and peak isokinetic joint moments were analyzed using a mixed-model ANOVA with repeated measures. All other comparisons were evaluated using independent t-tests.

RESULTS

Persons with PD produced smaller ankle plantarflexion moment at both 90° per second and 120° per second (P < 0.05). Relative effort during GI (271% vs 189%, P < 0.05) and gait (270% vs 161%, P < 0.05) was significantly greater at the ankle in persons with PD. Contribution of the ankle to the support moment was lower in PD during stair ascending (24% vs 34%) and GI (63% vs 57%) compared with that in controls.

CONCLUSIONS

The reduced ankle moments during ADL are indicative of deficits in muscular capabilities in those with PD. Moreover, PD caused a redistribution of joint torques, such that PD participants used their hip extensors more and ankle plantarflexors less.

Sarcopenia and Dynapenia in Patients With Parkinsonism

OBJECTIVES

To estimate prevalence of sarcopenia and dynapenia in outpatients with Parkinson disease (PD) and to investigate their association with the features of the disease.

DESIGN

Cross-sectional study.

SETTING

A specialized tertiary care center.

PARTICIPANTS

Consecutive patients (n = 364) aged 65 years or older, affected by parkinsonian syndromes.

MEASUREMENTS

Skeletal muscle mass (SMM), as well as strength and gait speed (GS) were assessed by bioimpedence analysis, handgrip dynamometry, and the 4-meter walking test, respectively. Based on these assessments, sarcopenia was diagnosed using the European Working Group on Sarcopenia in Older People criteria. Dynapenia was defined as handgrip strength less than 30 kg in men and less than 20 kg in women.

RESULTS

In total, 235 patients (64.6%) had a diagnosis of idiopathic PD. Low SMM index was recorded in 27 patients. Due to gait disturbances and postural instability, GS could not be measured in 98 patients and was found to be reduced in 61.3% of those assessed. Prevalence of sarcopenia and dynapenia was 6.6% (95% confidence interval [CI] 4.3-9.7) and 75.5% (95% CI 70.8-79.9), respectively. Sarcopenia tended to be higher in patients unable to perform GS assessment and was unrelated to the type of parkinsonian syndrome. It was associated with older age, longer disease duration, more severe disease, and higher disability in activities of daily living, as assessed by disease-specific clinical rating scale. Dynapenia was directly associated with parkinsonism other than PD, older age, and disability, whereas regular physical therapy appeared to be a preventive factor. However, it was unrelated to disease duration and severity. Finally, the disability score of activities of daily living was inversely correlated with handgrip strength and GS, whereas no association was found with SMM index.

CONCLUSION

Being primarily motor disorders, parkinsonian syndromes are characterized by progressive disability in performing activities of daily living. Impaired functional status is a prominent feature of this patient population, independently of disease duration and severity. Sarcopenia is mainly related to advancing disease and, due to a significant sparing of SMM, is an infrequent condition, likely to play a minor role in disability. Several factors could be responsible for this favorable body composition (eg, motor symptoms, levodopa therapy) and deserve further investigation. The prognostic impact of sarcopenia also needs to be addressed.

Contribution of Step Length to Increase Walking and Turning Speed as a Marker of Parkinson's Disease Progression

When increasing ambulation speed in Parkinson’s disease, step cadence increases more than stride length, indicating movement scaling difficulties that affect step generation in particular. We investigated whether step length variation when increasing ambulation speed was related to disease progression. Patients with Parkinson’s disease (N = 39) and controls (N = 152) performed two timed ambulation tasks: at a 'free' (self-selected) pace and then at 'maximal' speed. The total number of steps (including during turns) and time to complete the task were clinically measured. The relative contribution of step length and cadence to increased ambulation speed was determined using two methods: the ratios of change in step length or in cadence to the change in ambulation speed, and the step length index. While the relative contribution of step length and cadence to increased ambulation speed was independent of age in both control and patient groups, in Parkinson’s disease there was a negative correlation between time from diagnosis and the ratio of change in step length to change in ambulation speed (R = 0.54; p = 0.0004) and the step length index (R = 0.56, p = 0.0002). In parallel, there was a positive correlation between time since diagnosis and the ratio of change in cadence to change in ambulation speed (R = 0.57; p = 0.0002). The relative contribution of step length and cadence to increased ambulation speed is age invariant but a marker of Parkinson's disease advancement, and can be easily determined in the clinical setting.

Work and power reduced in L-dopa naïve patients in the early-stages of Parkinson’s disease

ABSTRACT Studies which have investigated muscular performance during the initial stages of Parkinson´s disease (PD) without L-dopa treatments were not found. Objective to assess whether muscular performance, work and power, of the trunk and lower limbs in L-dopa naïve patients in the early stages of PD was lower than those of healthy subjects and to compare muscular performance between the lower limbs. Method Ten subjects with PD, Hoehn and Yahr (HY) I-II, L-dopa naïve and 10 subjects in the control group were assessed with the isokinetic dynamometer. Results ANOVAs revealed that work and power measures of the trunk, hip, knee, and ankle muscular groups were lower in PD compared with the control group (p < 0.05). There were no significant differences in muscular performance between the lower limbs. Conclusion The results suggested the use of specific exercises, as rehabilitation strategies, to improve the ability to produce work and power with this population.

Effects of Resistance Training on Measures of Muscular Strength in People with Parkinson's Disease: A Systematic Review and Meta-Analysis

OBJECTIVE

The aim of this systematic review and meta-analysis was to determine the overall effect of resistance training (RT) on measures of muscular strength in people with Parkinson's disease (PD).

METHODS

Controlled trials with parallel-group-design were identified from computerized literature searching and citation tracking performed until August 2014. Two reviewers independently screened for eligibility and assessed the quality of the studies using the Cochrane risk-of-bias-tool. For each study, mean differences (MD) or standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated for continuous outcomes based on between-group comparisons using post-intervention data. Subgroup analysis was conducted based on differences in study design.

RESULTS

Nine studies met the inclusion criteria; all had a moderate to high risk of bias. Pooled data showed that knee extension, knee flexion and leg press strength were significantly greater in PD patients who undertook RT compared to control groups with or without interventions. Subgroups were: RT vs. control-without-intervention, RT vs. control-with-intervention, RT-with-other-form-of-exercise vs. control-without-intervention, RT-with-other-form-of-exercise vs. control-with-intervention. Pooled subgroup analysis showed that RT combined with aerobic/balance/stretching exercise resulted in significantly greater knee extension, knee flexion and leg press strength compared with no-intervention. Compared to treadmill or balance exercise it resulted in greater knee flexion, but not knee extension or leg press strength. RT alone resulted in greater knee extension and flexion strength compared to stretching, but not in greater leg press strength compared to no-intervention.

DISCUSSION

Overall, the current evidence suggests that exercise interventions that contain RT may be effective in improving muscular strength in people with PD compared with no exercise. However, depending on muscle group and/or training dose, RT may not be superior to other exercise types. Interventions which combine RT with other exercise may be most effective. Findings should be interpreted with caution due to the relatively high risk of bias of most studies.