Muscle weakness in Parkinson's disease: a follow-up study

The Role of Muscle Strength in the Sit-to-Stand Task in Parkinson's Disease

Background

Rising from a chair or the sit-to-stand (STS) task is frequently impaired in individuals with Parkinson's disease (PD). These patients commonly attribute such difficulties to weakness in the lower extremities. However, the role of muscle strength in the STS transfer task has not been fully elucidated.

Objective

We aim at determining the role of muscle strength in the STS task.

Methods

We studied 90 consecutive patients with PD and 52 sex- and age-matched controls. Lower limb strength was determined in both legs by clinical examination using the Medical Research Council Scale, dynamometric (leg flexion) and weighting machine (leg pressure) measures. Patients were interrogated regarding the presence of subjective lower limb weakness or allied sensations.

Results

There were 20 patients (22.2%) with abnormal STS task (item 3.9 of the MDS-UPDRS-III ≥2 points). These patients had higher modified Hoehn and Yahr stage (P  <  0.001) and higher total motor scores of the MDS-UPDRS(P  <  0.001), compared with 70 PD patients with normal STS task. Patients with abnormal STS task endorsed lower limb weakness more frequently and had lower muscle strength in the proximal lower extremities, compared to PD patients with normal STS task and normal controls. The presence of perceived lower limb weakness increased the risk of an abnormal STS task, OR: 11.93 (95% C.I. 1.51-94.32), whereas a hip extension strength ≤9 kg/pressure also increased the risk of abnormal STS task, OR: 4.45 (95% C.I. 1.49-13.23). In the multivariate regression analysis, bradykinesia and decreased hip strength were related to abnormal STS task.

Conclusions

Patients with PD and abnormal STS task complain more commonly of lower limb weakness and have decreased proximal lower limb strength compared to patients with PD and normal STS task, likely contributing to abnormalities in performing the STS task.

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.

Leg Muscle Strength Correlates with Gait Performance in Advanced Parkinson Disease

Objective Leg muscle strength (LMS) is decreased in early-stage Parkinson disease (PD) patients and is associated with slower walking and falls. However, LMS in advanced PD has not been well investigated. The purpose of this study was to evaluate LMS in advanced PD patients and its effects on gait performance, activities of daily living, and the cognitive function. Methods The medical records of 132 patients with idiopathic advanced PD [Hoehn and Yahr (H&Y) stages 3 and 4] with a mean disease duration of 9.6 years were retrospectively reviewed. Leg extensor muscle strength of the patients was measured using a Strength Ergo 240. The associations between the LMS and gait performance, Barthel index, H&Y stage, and Mini-Mental State Examination (MMSE) score were analyzed. Results A Spearman's correlation analysis showed that LMS was correlated with the sex, age, age of disease onset, H&Y stage, Barthel index, MMSE score, and gait parameters. A multivariable linear regression analysis for identifying predictors of LMS showed that the gait velocity (β=0.377), Barthel index (β=0.281), sex (β=-0.187), and disease duration (β=-0.155) were significant. A receiver operating characteristic curve analysis for discriminating between H&Y stage 3 and 4 was performed for LMS; the area under the curve was 0.774 (95% confidence interval=0.696-0.851). Conclusions LMS was strongly associated with multiple domains of clinical characteristics, especially gait velocity and the Barthel index. Our study also suggested that LMS can be a predictor of PD progression.

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.

Insufficiency of trunk extension and impaired control of muscle force in Parkinson's disease with camptocormia

OBJECTIVE

To examine the aetiology of parkinsonian camptocormia, a non-fixed pathological forward bending of the trunk, by measuring trunk muscle activation and force regulation in Parkinson patients with (PD + CC) and without (PD) camptocormia matched for disease severity, and in age- and sex-matched healthy controls (HC).

METHODS

The isometric forces of trunk extension and flexion were measured in PD + CC, PD and HC. Neuromuscular efficiency (increase of extension force per increase of paravertebral muscle surface electromyography signal) and the ability to maintain a constant submaximal trunk extension force were examined.

RESULTS

Peak trunk extension force was significantly lower in PD + CC and PD than in HC, with PD + CC non-significantly weaker than PD. Compared with HC and with PD, the neuromuscular efficiency of trunk extension was significantly reduced in PD + CC. The variability of the force output (coefficient of variation) was significantly larger for PD + CC than for HC or PD.

CONCLUSION

The reduced neuromuscular efficiency of trunk extension separates PD + CC from PD. Moreover, control of the trunk extensor force is impaired in PD + CC.

SIGNIFICANCE

There is weakness and a force control deficit in parkinsonian camptocormia suggesting a disturbed sensory-motor integration, which may contribute to myopathic changes in the trunk extensor muscles.

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.

Maximum Step Length Test Performance in People With Parkinson Disease: A Cross-sectional Study

BACKGROUND AND PURPOSE

The Maximum Step Length Test (MSLT), a measure of one's capacity to produce a large step, has been studied in older adults, but not in people with Parkinson disease (PD). We characterized performance and construct validity of the MSLT in PD.

METHODS

Forty participants (mean age: 65.12 ± 8.20 years; 45% female) with idiopathic PD completed the MSLT while "OFF" and "ON" anti-PD medication. Construct validity was investigated by examining relationships between MSLT and measures of motor performance. The following measures were collected: Mini-Balance Evaluation Systems Test (Mini-BESTest), Activities-specific Balance Confidence (ABC) scale, gait velocity, 6-minute walk test (6MWT), Movement Disorder Society-Unified Parkinson Disease Rating Scale subsection III (MDS-UPDRS III), and Timed Up and Go (TUG) test. A repeated-measures analysis of variance tested for main effects of medication and stepping direction and the interaction between the 2. Pearson or Spearman correlations were used to assess the relationships between MSLT and motor performance measures (α = 0.05).

RESULTS

Regardless of medication status, participants stepped further in the forward direction compared with the backward and lateral directions (P < 0.001). Participants increased MSLT performance when ON-medication compared with OFF-medication (P = 0.004). Regardless of medication status, MSLT was moderately to strongly related to Mini-BESTest, TUG, and 6MWT.

DISCUSSION AND CONCLUSIONS

People with PD stepped furthest in the forward direction when performing the MSLT. Increased MSLT performance was observed in the ON-medication state compared with OFF-medication; however, the small increase may not be clinically meaningful. Given the relationships between the MSLT and the Mini-BESTest, 6MWT, and TUG, MSLT performance appears to be associated with balance and gait hypokinesia in people with PD.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A186).

Physical therapy and deep brain stimulation in Parkinson's Disease: protocol for a pilot randomized controlled trial

Background

Subthalamic nucleus deep brain stimulation (STN-DBS) reduces tremor, muscle stiffness, and bradykinesia in people with Parkinson’s Disease (PD). Walking speed, known to be reduced in PD, typically improves after surgery; however, other important aspects of gait may not improve. Furthermore, balance may worsen and falls may increase after STN-DBS. Thus, interventions to improve balance and gait could reduce morbidity and improve quality of life following STN-DBS. Physical therapy (PT) effectively improves balance and gait in people with PD, but studies on the effects of PT have not been extended to those treated with STN-DBS. As such, the efficacy, safety, and feasibility of PT in this population remain to be determined. The purpose of this pilot study is to address these unmet needs. We hypothesize that PT designed to target balance and gait impairment will be effective, safe, and feasible in this population.

Methods/design

Participants with PD treated with STN-DBS will be randomly assigned to either a PT or control group. Participants assigned to PT will complete an 8-week, twice-weekly PT program consisting of exercises designed to improve balance and gait. Control group participants will receive the current standard of care following STN-DBS, which does not include prescription of PT. The primary aim is to assess preliminary efficacy of PT on balance (Balance Evaluation Systems Test). A secondary aim is to assess efficacy of PT on gait (GAITRite instrumented walkway). Participants will be assessed OFF medication/OFF stimulation and ON medication/ON stimulation at baseline and at 8 and 12 weeks after baseline. Adverse events will be measured over the duration of the study, and adherence to PT will be measured to determine feasibility.

Discussion

To our knowledge, this will be the first study to explore the preliminary efficacy, safety, and feasibility of PT for individuals with PD with STN-DBS. If the study suggests potential efficacy, then this would justify larger trials to test effectiveness and safety of PT for those with PD with STN-DBS.

Trial registration

NCT03181282 (clinicaltrials.gov). Registered on 7 June 2017.

Electronic supplementary material

The online version of this article (10.1186/s40814-018-0243-2) contains supplementary material, which is available to authorized users.

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.

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.

Incorporating yoga into an intense physical therapy program in someone with Parkinson's disease: a case report

PURPOSE

The purpose of this case report was to document outcomes following an intense exercise program integrating yoga with physical therapy exercise in a male with Parkinson's disease.

METHOD

The participant performed an intense 1½-hour program (Phase A) incorporating strengthening, balance, agility and yoga exercises twice weekly for 12 weeks. He then completed a new home exercise program developed by the researchers (Phase B) for 12 weeks.

RESULTS

His score on the Parkinson's Disease Questionnaire improved 16 points while his score on the High Level Mobility Assessment tool improved 11 points. There were also improvements in muscle length of several lower extremity muscles, in upper and lower extremity muscle strength, in dynamic balance and he continues to work full time 29 months later. There were no improvements in thoracic posture or aerobic power.

DISCUSSION

This intense program was an effective dose of exercise for someone with Parkinson's disease and allowed him to continue to participate in work, leisure, and community activities.

Altered Dynamic Postural Control during Step Turning in Persons with Early-Stage Parkinson's Disease

Persons with early-stage Parkinson's disease (EPD) do not typically experience marked functional deficits but may have difficulty with turning tasks. Studies evaluating turning have focused on individuals in advanced stages of the disease. The purpose of this study was to compare postural control strategies adopted during turning in persons with EPD to those used by healthy control (HC) subjects. Fifteen persons with EPD, diagnosed within 3 years, and 10 HC participated. Participants walked 4 meters and then turned 90°. Dynamic postural control was quantified as the distance between the center of pressure (COP) and the extrapolated center of mass (eCOM). Individuals with EPD demonstrated significantly shorter COP-eCOM distances compared to HC. These findings suggest that dynamic postural control during turning is altered even in the early stages of PD.

Lower extremity isokinetic muscle strength in patients with Parkinson's disease

We evaluated lower extremity isokinetic muscle strength to determine affected muscle groups and their dependence on movement velocity, and to establish the relationship between muscle strength and clinical severity, as well as muscle strength and falls, in Parkinson's disease (PD). Twenty-five patients diagnosed with PD and 24 healthy volunteers were enrolled in this study. Lower extremity muscle strength was measured using an isokinetic dynamometer. Each participant's clinical status was examined in accordance with the Unified Parkinson's Disease Rating Scale; fall history was also recorded. We observed a significant decrease in isokinetic muscle strength in the patient group, especially in both hip and knee flexors and extensors. Decreased muscle strength was independent of velocity, and correlated with clinical severity and falls. Movement velocity-independent lower extremity isokinetic muscle weakness has been observed in patients with PD, especially in the knee and hip joints. The evaluation of isokinetic muscle strength may be a useful tool for the assessment of clinical severity and falls in PD.

Is there muscular weakness in Parkinson's disease?

Controversy exists as to whether muscle weakness is present in Parkinson's disease (PD). Computerized literature searches identified clinical trials and reviews about muscular strength assessment in patients with Parkinson's disease, using the following databases: PubMed, Ovid MEDLINE, Ovid EMBASE, the Cochrane Database of Systematic Reviews, Cumulative Index to Nursing and Allied Health Literature, and Physiotherapy Evidence Database. Seventeen articles fulfilled all criteria for selection. These studies suggested that isokinetic muscle strength was decreased in patients with Parkinson's disease and that muscle weakness was not specifically related to tremor or rigidity. Bilateral asymmetrical muscle weakness was present in Parkinson's disease when presenting with clinical unilateral hemiparkinsonism. Recent studies using sensitive mechanical devices have provided evidence that muscle strength is reduced in patients with Parkinson's disease compared with age-matched controls. The specific cause of this weakness is not known. Questions under debate were whether this weakness was of central or peripheral origin and whether it was intrinsic to the disease or a secondary phenomenon.

Parkinson's disease and resistive exercise: rationale, review, and recommendations

Individuals with Parkinson's disease (PD) are not only burdened with disease-specific symptoms (i.e., bradykinesia, rigidity, and tremor), but are also confronted with age-associated progressive loss of physical function, perhaps to a greater extent than neurologically normal adults. Suggestions for the inclusion of resistive exercise into treatment to attenuate these symptoms were made over 10 years ago, yet very few well controlled investigations are available. The objective of this review is to establish a clear rationale for the efficacy of resistance training in individuals with PD. Specifically, we highlight musculoskeletal weakness and its relationship to function as well as potential training-induced adaptive alterations in the neuromuscular system. We also review the few resistance training interventions currently available, but limit this review to those investigations that provide a quantitative exercise prescription. Finally, we recommend future lines of inquiry warranting further attention and call to question the rationale behind current exercise prescriptions. The absence of reports contraindicating resistive exercise, the potential for positive adaptation, and the noted benefits of resistance training in other populations may provide support for its inclusion into a treatment approach to PD.

High-intensity resistance training amplifies muscle hypertrophy and functional gains in persons with Parkinson's disease

Strength deficits in persons with Parkinson's disease (PD) have been identified as a contributor to bradykinesia. However, there is little research that examines the effect of resistance training on muscle size, muscle force production, and mobility in persons with PD. The purpose of this exploratory study was to examine, in persons with PD, the changes in quadriceps muscle volume, muscle force production, and mobility as a result of a 12-week high-force eccentric resistance training program and to compare the effects to a standard-care control. Nineteen individuals with idiopathic PD were recruited and consented to participate. Matched assignment for age and disease severity resulted in 10 participants in the eccentric group and 9 participants in the control group. All participants were tested prior to and following a 12-week intervention period with testing and training conducted at standardized times in their medication cycle. The eccentric group performed high-force quadriceps contractions on an eccentric ergometer 3 days a week for 12 weeks. The standard-care group exercise program encompassed standard exercise management of PD. The outcome variables were quadriceps muscle volume, muscle force, and mobility measures (6-minute walk, stair ascent/descent time). Each outcome variable was tested using separate one-way analyses of covariance on the difference scores. Muscle volume, muscle force, and functional status improvements occurred in persons with PD as a result of high-force eccentric resistance training. The eccentric group demonstrated significantly greater difference scores for muscle structure, stair descent, and 6-minute walk (P < 0.05). Magnitude of effect size estimators for the eccentric group consistently exceeded those in the standard-care group for all variables. To our knowledge, this is the first clinical trial to investigate and demonstrate the effects of eccentric resistance training on muscle hypertrophy, strength, and mobility in persons with PD. Additional research is needed to determine the anatomical and neurological mechanisms of the observed strength gains and mobility improvements.