Slowing of EEG waves correlates with striatal [18 F]fluorodopa PET/CT uptake and executive dysfunction in Parkinson's disease.

Parkinson's disease (PD) research on specific neuroimaging and neurophysiological biomarkers revealing executive dysfunction mechanisms is limited, necessitating validation. Thus, our study aimed to assess associations between electroencephalographic power spectral density (PSD-EEG), striatal [18 F]Fluorodopa uptake and neuropsychological executive function (EF) testing parameters in PD, while also estimating their diagnostic accuracy. We compared resting PSD-EEG, striatal [18 F]Fluorodopa uptake ratios based on positron emission computed tomography ([18 F]FDOPA PET/CT) and neuropsychological EF tests outcomes [Trail Making Test (TMT) and Stroop Test (ST)] between PD patients and healthy controls (HCO) and then calculated correlations among these measures separately for each group. Additionally, we estimated PD diagnostic accuracy of the PSD-EEG and [18 F]FDOPA PET/CT parameters. In PD patients, we observed the following: (i) slower EEG waves, reflected in increased power of the EEG theta and lower-alpha bands in frontal lobe areas; (ii) reduced [18 F]FDOPA PET/CT uptake in the putaminal and caudate nuclei, along with a decreased putamen-to-caudate ratio ([18 F]FDOPA PET/CT PCR); and (iii) longer performance times evident in nearly all EF tests' parameters. Slower EEG waves correlated negatively with [18 F]FDOPA PET/CT PCR and positively with most of the EF test parameters. Furthermore, we found negative correlations between [18 F]FDOPA PET/CT PCR and certain EF measures related to ST. [18 F]FDOPA PET/CT ratios and several PSD-EEG parameters, particularly those from the prefrontal cortex, demonstrated clinically reasonable diagnostic accuracy for PD. In conclusion, EEG waves slowing in the frontal lobe were correlated with striatal dopaminergic deficiency and impaired executive function in mild PD patients and showed promise as a biomarker of PD-related executive dysfunction.

Motor imagery training of goal-directed reaching in relation to imagery of reaching and grasping in healthy people.

The study aimed to determine whether four weeks of motor imagery training (MIT) of goal-directed reaching (reaching to grasp task) would affect the cortical activity during motor imagery of reaching (MIR) and grasping (MIG) in the same way. We examined cortical activity regarding event-related potentials (ERPs) in healthy young participants. Our study also evaluated the subjective vividness of the imagery. Furthermore, we aimed to determine the relationship between the subjective assessment of motor imagery (MI) ability to reach and grasp and the cortical activity during those tasks before and after training to understand the underlying neuroplasticity mechanisms. Twenty-seven volunteers participated in MIT of goal-directed reaching and two measurement sessions before and after MIT. During the sessions 128-channel electroencephalography (EEG) was recorded during MIR and MIG. Also, participants assessed the vividness of the MI tasks using a visual analog scale (VAS). The vividness of imagination improved significantly (P < .05) after MIT. A repeated measures ANOVA showed that the task (MIR/MIG) and the location of electrodes had a significant effect on the ERP's amplitude (P < .05). The interaction between the task, location, and session (before/after MIT) also had a significant effect on the ERP's amplitude (P < .05). Finally, the location of electrodes and the interaction between location and session had a significant effect on the ERP's latency (P < .05). We found that MIT influenced the EEG signal associated with reaching differently than grasping. The effect was more pronounced for MIR than for MIG. Correlation analysis showed that changes in the assessed parameters due to MIT reduced the relationship between the subjective evaluation of imagining and the EEG signal. This finding means that the subjective evaluation of imagining cannot be a simple, functional insight into the bioelectrical activity of the cerebral cortex expressed by the ERPs in mental training. The changes we noted in ERPs after MIT may benefit the use of non-invasive EEG in the brain-computer interface (BCI) context.Trial registration: NCT04048083.

Effect of gender, muscle type and skinfold thickness on myometric parameters in young people.

BACKGROUND: The aim of the study was to compare the mechanical properties of three human skeletal muscles: biceps brachii (BB), rectus femoris (RF), and tibialis anterior (TA) at rest measured by myoton device in males (n = 16, mean age 21.2 ± 0.6 years) and females (n = 16; 21.2 ± 0.9 years) and to investigate the influence of skin and subcutaneous tissue thickness (skinfold thickness, SFT) and gender on myometric parameters of the three skeletal muscles. METHODS: We measured the following mechanical and viscoelastic muscle properties using MyotonPRO®: frequency (F [Hz]), decrement (D [log]), stiffness (S [N/m]), relaxation time (R [ms]) and creepability (C [De]). The values of SFT for all selected muscles were assessed by caliper. A mixed-design analysis of variance with gender as between subject comparison was used for assessing the differences between gender and muscles in SFT and each of the myometric parameters separately (F, D, S, R and C). Pearson correlation coefficient or Spearman's rank correlation coefficient between SFT and myometric parameters was conducted for males, females and males and females together. The level of statistical significance was set at α ≤ 0.05 with Bonferroni correction for multiple comparisons. RESULTS: The SFT over the RF, TA, and BB muscles in women was statistically significantly larger compared with that of males. In females and males, the SFT over the RF was larger than over the TA and BB, and the SFT over the TA was larger compared with over the BB. The values of F and S recorded for the TA muscle were the highest among the three muscles, while D, C, and R were lowest in TA but highest in the RF muscle in men and women. The values of F and S were smaller in females than in males. Gender comparison of D, C, and R values showed that only D for the RF was significantly lower in females than in males, and C for the RF and TA was significantly larger in females than in males. Some correlation between SFT and myometric parameters were different between males and females. For example, there was a significant, negative correlation between SFT and F for all muscles in females, and a significant, positive correlation between these parameters for BB and TA (not for RF) in males. For pooled data (males and females together), a negative significant correlation between SFT and F was observed for RF and TA (not significant for BB muscle). DISCUSSION: It is concluded that the TA compared with the BB and RF has significantly greater F and S but the smallest D and C and the shortest R. Gender and muscle differences in the SFT may affect the measurements of muscle properties using MyotonPRO®. The relationship between SFT and myometric parameters is different in males and females in the RF, TA, and BB muscles. Therefore, the myometric data should be analyzed in males and females separately.

Motor Imagery Training of Reaching-to-Grasp Movement Supplemented by a Virtual Environment in an Individual With Congenital Bilateral Transverse Upper-Limb Deficiency.

This study explored the effect of kinesthetic motor imagery training on reaching-to-grasp movement supplemented by a virtual environment in a patient with congenital bilateral transverse upper-limb deficiency. Based on a theoretical assumption, it is possible to conduct such training in this patient. The aim of this study was to evaluate whether cortical activity related to motor imagery of reaching and motor imagery of grasping of the right upper limb was changed by computer-aided imagery training (CAIT) in a patient who was born without upper limbs compared to a healthy control subject, as characterized by multi-channel electroencephalography (EEG) signals recorded before and 4, 8, and 12 weeks after CAIT. The main task during CAIT was to kinesthetically imagine the execution of reaching-to-grasp movements without any muscle activation, supplemented by computer visualization of movements provided by a special headset. Our experiment showed that CAIT can be conducted in the patient with higher vividness of imagery for reaching than grasping tasks. Our results confirm that CAIT can change brain activation patterns in areas related to motor planning and the execution of reaching and grasping movements, and that the effect was more pronounced in the patient than in the healthy control subject. The results show that CAIT has a different effect on the cortical activity related to the motor imagery of a reaching task than on the cortical activity related to the motor imagery of a grasping task. The change observed in the activation patterns could indicate CAIT-induced neuroplasticity, which could potentially be useful in rehabilitation or brain-computer interface purposes for such patients, especially before and after transplantation. This study was part of a registered experiment (ID: NCT04048083).

High-density surface electromyography maps after computer-aided training in individual with congenital transverse deficiency: a case study.

BACKGROUND: The aim of this study was to determine whether computer-aided training (CAT) of motor tasks would increase muscle activity and change its spatial distribution in a patient with a bilateral upper-limb congenital transverse deficiency. We believe that our study makes a significant contribution to the literature because it demonstrates the usefulness of CAT in promoting the neuromuscular adaptation in people with congenital limb deficiencies and altered body image. CASE PRESENTATION: The patient with bilateral upper-limb congenital transverse deficiency and the healthy control subject performed 12 weeks of the CAT. The subject's task was to imagine reaching and grasping a book with the hand. Subjects were provided a visual animation of that movement and sensory feedback to facilitate the mental engagement to accomplish the task. High-density electromyography (HD-EMG; 64-electrode) were collected from the trapezius muscle during a shrug isometric contraction before and after 4, 8, 12 weeks of the training. After training, we observed in our patient changes in the spatial distribution of the activation, and the increased average intensity of the EMG maps and maximal force. CONCLUSIONS: These results, although from only one patient, suggest that mental training supported by computer-generated visual and sensory stimuli leads to beneficial changes in muscle strength and activity. The increased muscle activation and changed spatial distribution of the EMG activity after mental training may indicate the training-induced functional plasticity of the motor activation strategy within the trapezius muscle in individual with bilateral upper-limb congenital transverse deficiency. Marked changes in spatial distribution during the submaximal contraction in the patient after training could be associated with changes of the neural drive to the muscle, which corresponds with specific (unfamiliar for patient) motor task. These findings are relevant to neuromuscular functional rehabilitation in patients with a bilateral upper-limb congenital transverse deficiency especially before and after upper limb transplantation and to development of the EMG based prostheses.

Eight Weeks of Aerobic Interval Training Improves Psychomotor Function in Patients with Parkinson's Disease-Randomized Controlled Trial.

BACKGROUND: This study examined the generalized effects of cycle ergometer aerobic interval training (AIT) on psychomotor behaviors in individuals with Parkinson's disease (PD), including bimanual motor control, cognitive function, and neurological motor and non-motor parkinsonian signs. METHODS: Twenty mild to moderate PD patients were randomly allocated to the following groups: (1) trained group (PD-TR, n = 10), which besides receiving usual care, underwent an 8-week moderate intensity AIT program; or (2) control group (PD-CO, n = 10) which received usual care, including participation in conventional physical therapy. Both groups were tested before and after the 8-week AIT program period with the following assessments: (1) laboratory analyses of bimanual motor control, (2) psychological evaluation of cognitive function, and (3) an evaluation of neurological parkinsonian signs. RESULTS: The PD-TR group exhibited improved (1) bimanual motor control, reflected by a decreased time (p = 0.013) and increased rate of grip force development (p = 0.013) in the manipulating hand and a decreased time delay between grip force initiation in the manipulating and stabilizing hand (p = 0.020); (2) executive function, reflected by decreased performance time in part II of the Stroop Test (p = 0.007); and (3) neurological parkinsonian signs, reflected by an amelioration of upper-extremity bradykinesia (p = 0.015) and improvement in daily life manual functions (p = 0.004), mood, and intellectual function (p = 0.005). CONCLUSIONS: Following an 8-week moderate intensity AIT program, patients with PD exhibited improved psychomotor behaviors, reflected by bimanual motor control, executive function, and neurological parkinsonian signs.

Influence of dopaminergic treatment on resting elbow joint angle control mechanisms in patients with Parkinson's disease - a preliminary report.

PURPOSE: Heightened tonic stretch reflex contributes to increased muscle tone and a more-flexed resting elbow joint angle (EJA) in patients with Parkinson's disease (PD). Dopaminergic medication restores central nervous system (CNS) functioning and decreases resting muscle electrical and mechanical activities. This study aimed to evaluate the effects of dopaminergic medication on parkinsonian rigidity, resting EJA, resting electrical activity (electromyography, EMG) and mechanical properties (myotonometry, MYO) of elbow flexor muscles and the associations of EJA with these muscles resting electrical activity and mechanical properties in PD patients. We also evaluated a relationship between dopaminergic treatment dose and these outcome measures values. METHODS: Ten PD patients (age 68 ± 10.1 years; body mass 70 ± 16.8 kg; height 162 ± 6.6 cm; illness duration 9 ± 4.5 years) were tested during medication on- and off-phases. Resting EJA, myotonometric muscle stiffness (S-MYO) and root mean square electromyogram amplitude (RMS-EMG) were recorded from relaxed biceps brachii and brachioradialis muscles. Based on the above parameters, we also calculated the EJA/S-MYO ratio and EJA/RMS-EMG ratio. Parkinsonian rigidity was assessed using the motor section of the Unified Parkinson's Disease Rating Scale. RESULTS: EJA, EJA/S-MYO ratio, and EJA/RMS-EMG ratio were increased and S-MYO, RMS-EMG, and parkinsonian rigidity were decreased during the medication on-phase compared with the off-phase. In addition, the dopaminergic treatment dose was negatively correlated with S-MYO and RMS-EMG, and positively correlated with EJA/SMYO and EJA/RMS-EMG ratios. CONCLUSIONS: We conclude that dopaminergic medication- induced improvements in resting elbow joint angle in tested patients with PD are related to changes in their muscle electrical and mechanical properties.

Computer-aided training sensorimotor cortex functions in humans before the upper limb transplantation using virtual reality and sensory feedback.

One of the biggest problems of upper limb transplantation is lack of certainty as to whether a patient will be able to control voluntary movements of transplanted hands. Based on findings of the recent research on brain cortex plasticity, a premise can be drawn that mental training supported with visual and sensory feedback can cause structural and functional reorganization of the sensorimotor cortex, which leads to recovery of function associated with the control of movements performed by the upper limbs. In this study, authors - based on the above observations - propose the computer-aided training (CAT) system, which generating visual and sensory stimuli, should enhance the effectiveness of mental training applied to humans before upper limb transplantation. The basis for the concept of computer-aided training system is a virtual hand whose reaching and grasping movements the trained patient can observe on the VR headset screen (visual feedback) and whose contact with virtual objects the patient can feel as a touch (sensory feedback). The computer training system is composed of three main components: (1) the system generating 3D virtual world in which the patient sees the virtual limb from the perspective as if it were his/her own hand; (2) sensory feedback transforming information about the interaction of the virtual hand with the grasped object into mechanical vibration; (3) the therapist's panel for controlling the training course. Results of the case study demonstrate that mental training supported with visual and sensory stimuli generated by the computer system leads to a beneficial change of the brain activity related to motor control of the reaching in the patient with bilateral upper limb congenital transverse deficiency.

Spike shape analysis of electromyography for parkinsonian tremor evaluation.

INTRODUCTION: Standard electromyography (EMG) parameters have limited utility for evaluation of Parkinson disease (PD) tremor. Spike shape analysis (SSA) EMG parameters are more sensitive than standard EMG parameters for studying motor control mechanisms in healthy subjects. SSA of EMG has not been used to assess parkinsonian tremor. This study assessed the utility of SSA and standard time and frequency analysis for electromyographic evaluation of PD-related resting tremor. METHODS: We analyzed 1-s periods of EMG recordings to detect nontremor and tremor signals in relaxed biceps brachii muscle of seven mild to moderate PD patients. RESULTS: SSA revealed higher mean spike amplitude, duration, and slope and lower mean spike frequency in tremor signals than in nontremor signals. Standard EMG parameters (root mean square, median, and mean frequency) did not show differences between the tremor and nontremor signals. CONCLUSIONS: SSA of EMG data is a sensitive method for parkinsonian tremor evaluation.

Interval training-induced alleviation of rigidity and hypertonia in patients with Parkinson's disease is accompanied by increased basal serum brain-derived neurotrophic factor.

OBJECTIVE: To examine the effects of cycloergometric interval training on parkinsonian rigidity, relaxed biceps brachii muscle tone in affected upper extremities, and serum level of brain-derived neurotrophic factor. DESIGN: Case series, repeated-measures design, pilot study. SUBJECTS/PATIENTS: Eleven patients with mild-to-moderate Parkinson's disease (Hoehn & Yahr scale 2.3 ± 0.72), recruited from a neurological clinic, underwent cycle training and were tested along with non-trained, healthy control subjects (n = 11) in a motor control laboratory. METHODS: Patients underwent 8 weeks of interval training (3 × 1-h sessions weekly, consisting of a 10-min warm-up, 40 min of interval exercise, and 10-min cool-down) on a stationary cycloergometer. Parkinsonian rigidity (Unified Parkinson's Disease-Rating-Scale) in the upper extremity, resting biceps brachii muscle tone (myometric stiffness and frequency), and brain-derived neurotrophic factor level were measured 1-3 days before interval training cycle started and 6-10 days after the last training session. RESULTS: Training resulted in a decrease in rigidity (p = 0.048) and biceps brachii myometric muscle stiffness (p = 0.030) and frequency (p = 0.006), and an increase in the level of brain-derived neurotrophic factor (p = 0.035) relative to pre-training values. The increase in brain-derived neurotrophic factor level correlated with improvements in parkinsonian rigidity (p = 0.025), biceps brachii myometric stiffness (p = 0.001) and frequency (p = 0.002). CONCLUSION: Training-induced alleviation of parkinsonian rigidity and muscle tone decrease may be associated with neuroplastic changes caused by a training-induced increase in the level of brain-derived neurotrophic factor.

Effects of submaximal eccentric exercise on muscle activity at different elbow joint angles.

Our study aimed to determine whether electrical and mechanical factors contributing to acute or long-term maximal torque reduction and muscle soreness due to submaximal eccentric exercise (ECC) are elbow-joint-angle specific and to what extent the joint angle affects the contribution of antagonist coactivation to this torque reduction. Maximal isometric torque (MIT), muscle soreness assessment, agonist electromechanical activities, and antagonist coactivation during the maximal voluntary contraction (MVC) were measured at elbow joint angles of 60°, 90°, and 150° before ECC, immediately after exercise, and 24, 48, 72, and 120 hr after exercise. ECC causes an immediate decrease in MIT as well as increased antagonist coactivation at three angles. Antagonist coactivation returned to its baseline level at 24 hr regardless of joint angle. The most rapid torque recovery and the highest force level at which pain occurred were found after ECC at a joint angle of 60°. During the recovery period, no mechanomyographical changes were observed when measuring surface mechanomyography changes at three angles, while the electrical activity differed between angles.

Myoelectrical manifestation of fatigue less prominent in patients with cancer related fatigue.

PURPOSE: A lack of fatigue-related muscle contractile property changes at time of perceived physical exhaustion and greater central than peripheral fatigue detected by twitch interpolation technique have recently been reported in cancer survivors with fatigue symptoms. Based on these observations, it was hypothesized that compared to healthy people, myoelectrical manifestation of fatigue in the performing muscles would be less significant in these individuals while sustaining a prolonged motor task to self-perceived exhaustion (SPE) since their central fatigue was more prominent. The purpose of this study was to test this hypothesis by examining electromyographic (EMG) signal changes during fatiguing muscle performance. METHODS: Twelve individuals who had advanced solid cancer and cancer-related fatigue (CRF), and 12 age- and gender-matched healthy controls performed a sustained elbow flexion at 30% maximal voluntary contraction till SPE. Amplitude and mean power frequency (MPF) of EMG signals of the biceps brachii, brachioradialis, and triceps brachii muscles were evaluated when the individuals experienced minimal, moderate, and severe fatigue. RESULTS: CRF patients perceived physical "exhaustion" significantly sooner than the controls. The myoelectrical manifestation of muscular fatigue assessed by EMG amplitude and MPF was less significant in CRF than controls. The lower MPF even at minimal fatigue stage in CRF may indicate pathophysiologic condition of the muscle. CONCLUSIONS: CRF patients experience less myoelectrical manifestation of muscle fatigue than healthy individuals near the time of SPE. The data suggest that central nervous system fatigue plays a more important role in limiting endurance-type of motor performance in patients with CRF.

Lack of muscle contractile property changes at the time of perceived physical exhaustion suggests central mechanisms contributing to early motor task failure in patients with cancer-related fatigue.

CONTEXT: Fatigue is one of the most common symptoms reported by cancer survivors, and fatigue worsens when patients are engaged in muscle exertion, which results in early motor task failure. Central fatigue plays a significant role, more than muscle (peripheral) fatigue, in contributing to early task failure in cancer-related fatigue (CRF). OBJECTIVES: The purpose of this study was to determine if muscle contractile property alterations (reflecting muscle fatigue) occurred at the end of a low-intensity muscle contraction to exhaustion and if these properties differed between those with CRF and healthy controls. METHODS: Ten patients (aged 59.9±10.6 years, seven women) with advanced solid cancer and CRF and 12 age- and gender-matched healthy controls (aged 46.6±12.8 years, nine women) performed a sustained contraction of the right arm elbow flexion at 30% maximal level until exhaustion. Peak twitch force, time to peak twitch force, rate of peak twitch force development, and half relaxation time derived from electrical stimulation-evoked twitches were analyzed pre- and post-sustained contraction. RESULTS: CRF patients reported significantly greater fatigue as measured by the Brief Fatigue Inventory and failed the motor task earlier, 340±140 vs. 503±155 seconds in controls. All contractile property parameters did not change significantly in CRF but did change significantly in controls. CONCLUSION: CRF patients perceive physical exhaustion sooner during a motor fatigue task with minimal muscular fatigue. The observation supports that central fatigue is a more significant factor than peripheral fatigue in causing fatigue feelings and limits motor function in cancer survivors with fatigue symptoms.

Strengthened functional connectivity in the brain during muscle fatigue.

Fatigue caused by sustaining submaximal-intensity muscle contraction(s) involves increased activation in the brain such as primary motor cortex (M1), primary sensory cortex (S1), premotor and supplementary motor area (PM&SMA) and prefrontal cortex (PFC). The synchronized increases in activation level in these cortical areas suggest fatigue-related strengthening of functional coupling within the motor control network. In the present study, this hypothesis was tested using the cross-correlation based functional connectivity (FC) analysis method. Ten subjects performed a 20-minute intermittent (3.5s ON/6.5s OFF, 120 trials total) handgrip task using the right hand at 50% maximal voluntary contraction (MVC) force level while their brain was scanned by a 3 T Siemens Trio scanner using echo planar imaging (EPI) sequence. A representative signal time course of the left M1 was extracted by averaging the time course data of a 2-mm cluster of neighboring voxels of local maximal activation foci, which was identified by a general linear model. Two FC activation maps were created for each subject by cross-correlating the time course data of the minimal (the first 10 trials) and significant (the last 10 trials) fatigue stages across all the voxels in the brain to the corresponding representative time course. Histogram and quantile regression analysis were used to compare the FC between the minimal and significant fatigue stages and the results showed a significant increase in FC among multiple cortical regions, including right M1 and bilateral PM&SMA, S1 and PFC. This strengthened FC indicates that when muscle fatigue worsens, many brain regions increase their coupling with the left M1, the primary motor output control center for the right handgrip, to compensate for diminished force generating capability of the muscle in a coordinated fashion by enhancing the descending command for greater muscle recruitment to maintain the same force.

Weakening of synergist muscle coupling during reaching movement in stroke patients.

BACKGROUND: After hemiparetic stroke, coordination of the shoulder flexor and elbow extensor muscles during a reaching movement is impaired and contributes to poor performance. OBJECTIVE: The aim was to determine whether functional coupling between electromyographic signals of synergist muscles during reaching was weakened in stroke patients who had poor motor coordination. METHODS: Surface electromyography (EMG) from the anterior deltoid, triceps brachii, biceps brachii, pectoralis major, supraspinatus, and latissimus dorsi of the affected upper limb in 11 stroke patients (mean Fugl-Meyer upper extremity score 27 ± 8) and in the dominant arm of 8 healthy controls were measured. RESULTS: Coherence between the EMG of the anterior deltoid and triceps brachii, 2 synergists for reaching, was lower in patients compared with controls, in the 0- to 11-Hz range. Detailed segmented frequency-range analysis indicated significant differences in the coherence between groups in 0- to 3.9-Hz and 4- to 7.9-Hz ranges. CONCLUSIONS: This weakened functional coupling may contribute to poor reaching performance and could be a consequence of a loss of common drive at the frequency bands as a result of interruption of information flow in the corticospinal pathway.

Higher muscle passive stiffness in Parkinson's disease patients than in controls measured by myotonometry.

OBJECTIVE: To assess muscle passive stiffness in medicated Parkinson's disease patients using myotonometry. DESIGN: Case-control study. SETTING: Kinesiology laboratory. PARTICIPANTS: Women with Parkinson's disease (PD) (n=8) and healthy matched elderly women (controls) (n=10) (mean age: PD, 77+/-3y; controls, 77+/-4y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Passive stiffness of relaxed biceps brachii (BB) muscle was measured using myotonometry. Additionally, surface electromyographic and mechanomyographic signals were recorded from the muscle at rest, and amplitude of those signals was analyzed offline. RESULTS: The values of BB muscle passive stiffness were significantly (P=.004) higher in PD than in the controls, with a statistically significant influence of parkinsonian rigidity score (Unified Parkinson's Disease Rating Scale) on intergroup differences (P<.001). The Spearman correlation coefficient rho value showed a significant (P=.005) positive relationship (rho=.866) between the parkinsonian rigidity score and passive stiffness values of BB in PD. The groups did not differ significantly in the electromyogram amplitude (P=.631) and mechanomyogram amplitude (P=.593) of the BB muscle, and values of these parameters did not correlate significantly with rigidity score (P=.555, P=.745, respectively) in the patients. CONCLUSIONS: Myotonometer is a sensitive enough tool to show that PD patients have higher muscle passive stiffness than healthy controls.

Electromyography and mechanomyography of elbow agonists and antagonists in Parkinson disease.

The purpose of this study was to assess the electromyographic (EMG) and mechanomyographic (MMG) activities of agonist and antagonist muscles in Parkinson disease patients during maximal isometric elbow contraction in flexion and extension. Ten elderly females with Parkinson disease (average age 75 years) and 10 age-matched healthy females were tested. The torque and the EMG and MMG signals from biceps brachii and triceps brachii were recorded during sustained maximal voluntary isometric contraction of the elbow flexors and extensors. There were no intergroup differences in the EMG and MMG activities of agonist and antagonist muscles or in torque. This might be because the Parkinson subjects were tested during their medication "ON" phase, or perhaps maximal isometric contraction (MVC) induced greater active muscle stiffness that affected the MMG signal. Muscle Nerve 40: 240-248, 2009.

Tensegrity principle in massage demonstrated by electro- and mechanomyography.

Based on a tensegrity principle, direct or indirect connections between fascia or muscles which stretch the aponeurosis or intermuscular septum may allow the transfer of tension over long distances, without loss of muscle force produced during rest and activity. The present study aimed to test an effect of massage on electrical (EMG) and mechanical (MMG) activities of a muscle lying distant, but indirectly connected to, the massaged muscle. Thirty-three healthy men participated in the study. To record the activity of the middle deltoid muscle the brachioradialis was massaged, and for the tensor fasciae latae-the peroneal muscles were massaged. An EMG/MMG hybrid probe was used to detect EMG and MMG signals from the middle deltoid and tensor fasciae latae muscles. The EMG amplitude increased during massage in the tensor fasciae lata only, while the MMG amplitude increased significantly in both muscles. It was concluded that there was an electrical as well as a mechanical response of muscle connected indirectly by structural elements with the muscle being massaged indicating an application for the tensegrity principle in massage therapy. It also has a practical importance, because it provides a means for a physiotherapist to influence adverse muscle tension by massaging another distant muscle.

EMG and MMG activities of agonist and antagonist muscles in Parkinson's disease patients during absolute submaximal load holding.

The purpose of the study was (1) to assess changes in electromyographical (EMG) and mechanomyographical (MMG) signals of the biceps and triceps brachii muscles during absolute submaximal load holding in Parkinson's disease patients tested during their medication "ON-phase" and in age-matched controls, and (2) to check whether mechanomyography can be useful in evaluation of neuromuscular system activity in Parkinson's disease patients. The data analysis was performed on nine females with Parkinson's disease and six healthy, age-matched females. The EMG and MMG signals were recorded from the short head of the biceps brachii (BB) and the lateral head of the triceps brachii (TB) muscles. It was concluded that compared to the controls, the Parkinson's disease patients exhibited higher amplitude in the biceps brachii muscle and lower median frequency of the MMG signal in the both tested muscles. However, no differences in the EMG amplitude and an increase of the EMG median frequency in the triceps brachii muscle of the Parkinson's disease group were observed. The MMG was not affected by physiological postural tremor and can depict differences between parkinsonians and controls, which may suggest that it is valuable tool for neuromuscular assessment for this condition.

A comparison between mechanomyographic condenser microphone and accelerometer measurements during submaximal isometric, concentric and eccentric contractions.

The aim of this study was to compare mechanomyogram (MMG) recorded by a condenser microphone (MIC) and an accelerometer (ACC) during submaximal isometric, concentric and eccentric contractions in 14 males. The maximal voluntary force (MVC) of the biceps brachii was measured. The subjects were asked to do short duration isometric, concentric and eccentric contraction at 10%, 30%, 50%, 70% MVC twice. For the concentric and eccentric contraction, the subject bent his arm for 3s (concentric) then held it for 3s and extended (eccentric) during 3s. The normalized root mean square (RMS) and mean power frequency (MPF) increased linearly with increased force for both transducers. There was a correlation between MIC MPF and ACC MPF at 10%, 30%, 50% MVC, and between MIC RMS and ACC RMS at 30% MVC during isometric contractions. There was significantly higher MPF for the ACC than for the MIC in concentric and eccentric modes, while the RMS did not differ among transducers in the three contraction modes. The RMS and MPF values coefficient of variations were significantly larger during anisometric contractions compared with isometric contractions and were lower for the accelerometer than for the microphone. The present results obtained during isometric, concentric and eccentric contractions of increased intensity showed that the information contained in microphone- and accelerometer-based MMG signals is different despite similar trends. It can be concluded that at low-moderate movement velocity, concentric contractions can be investigated by means of accelerometer and microphone.