Publications by authors named "Alberto Ranavolo"

55 Publications

An artificial neural network approach to detect presence and severity of Parkinson's disease via gait parameters.

PLoS One 2021 19;16(2):e0244396. Epub 2021 Feb 19.

Department of Medico-Surgical Sciences and Biotechnologies, University of Rome Sapienza, Latina, Italy.

Introduction: Gait deficits are debilitating in people with Parkinson's disease (PwPD), which inevitably deteriorate over time. Gait analysis is a valuable method to assess disease-specific gait patterns and their relationship with the clinical features and progression of the disease.

Objectives: Our study aimed to i) develop an automated diagnostic algorithm based on machine-learning techniques (artificial neural networks [ANNs]) to classify the gait deficits of PwPD according to disease progression in the Hoehn and Yahr (H-Y) staging system, and ii) identify a minimum set of gait classifiers.

Methods: We evaluated 76 PwPD (H-Y stage 1-4) and 67 healthy controls (HCs) by computerized gait analysis. We computed the time-distance parameters and the ranges of angular motion (RoMs) of the hip, knee, ankle, trunk, and pelvis. Principal component analysis was used to define a subset of features including all gait variables. An ANN approach was used to identify gait deficits according to the H-Y stage.

Results: We identified a combination of a small number of features that distinguished PwPDs from HCs (one combination of two features: knee and trunk rotation RoMs) and identified the gait patterns between different H-Y stages (two combinations of four features: walking speed and hip, knee, and ankle RoMs; walking speed and hip, knee, and trunk rotation RoMs).

Conclusion: The ANN approach enabled automated diagnosis of gait deficits in several symptomatic stages of Parkinson's disease. These results will inspire future studies to test the utility of gait classifiers for the evaluation of treatments that could modify disease progression.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0244396PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7894951PMC
February 2021

Critical Issues and Imminent Challenges in the Use of sEMG in Return-To-Work Rehabilitation of Patients Affected by Neurological Disorders in the Epoch of Human-Robot Collaborative Technologies.

Front Neurol 2020 22;11:572069. Epub 2020 Dec 22.

Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL, Rome, Italy.

Patients affected by neurological pathologies with motor disorders when they are of working age have to cope with problems related to employability, difficulties in working, and premature work interruption. It has been demonstrated that suitable job accommodation plans play a beneficial role in the overall quality of life of pathological subjects. A well-designed return-to-work program should consider several recent innovations in the clinical and ergonomic fields. One of the instrument-based methods used to monitor the effectiveness of ergonomic interventions is surface electromyography (sEMG), a multi-channel, non-invasive, wireless, wearable tool, which allows in-depth analysis of motor coordination mechanisms. Although the scientific literature in this field is extensive, its use remains significantly underexploited and the state-of-the-art technology lags expectations. This is mainly attributable to technical and methodological (electrode-skin impedance, noise, electrode location, size, configuration and distance, presence of crosstalk signals, comfort issues, selection of appropriate sensor setup, sEMG amplitude normalization, definition of correct sEMG-related outcomes and normative data) and cultural limitations. The technical problems are being resolved minimized also thanks to the possibility of using reference books and tutorials. Cultural limitations are identified in the traditional use of qualitative approaches at the expense of quantitative measurement-based monitoring methods to design and assess ergonomic interventions and train operators. To bridge the gap between the return-to-work rehabilitation and other disciplines, several teaching courses, accompanied by further electrodes and instrumentations development, should be designed at all Bachelor, Master and PhD of Science levels to enhance the best skills available among physiotherapists, and ergonomists.
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http://dx.doi.org/10.3389/fneur.2020.572069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7783040PMC
December 2020

The Sensor-Based Biomechanical Risk Assessment at the Base of the Need for Revising of Standards for Human Ergonomics.

Sensors (Basel) 2020 Oct 10;20(20). Epub 2020 Oct 10.

Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL, Monte Porzio Catone, 00040 Rome, Italy.

Due to the epochal changes introduced by "Industry 4.0", it is getting harder to apply the varying approaches for biomechanical risk assessment of manual handling tasks used to prevent work-related musculoskeletal disorders (WMDs) considered within the International Standards for ergonomics. In fact, the innovative human-robot collaboration (HRC) systems are widening the number of work motor tasks that cannot be assessed. On the other hand, new sensor-based tools for biomechanical risk assessment could be used for both quantitative "direct instrumental evaluations" and "rating of standard methods", allowing certain improvements over traditional methods. In this light, this Letter aims at detecting the need for revising the standards for human ergonomics and biomechanical risk assessment by analyzing the WMDs prevalence and incidence; additionally, the strengths and weaknesses of traditional methods listed within the International Standards for manual handling activities and the next challenges needed for their revision are considered. As a representative example, the discussion is referred to the lifting of heavy loads where the revision should include the use of sensor-based tools for biomechanical risk assessment during lifting performed with the use of exoskeletons, by more than one person (team lifting) and when the traditional methods cannot be applied. The wearability of sensing and feedback sensors in addition to human augmentation technologies allows for increasing workers' awareness about possible risks and enhance the effectiveness and safety during the execution of in many manual handling activities.
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http://dx.doi.org/10.3390/s20205750DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7599507PMC
October 2020

The Effects of Upper-Body Exoskeletons on Human Metabolic Cost and Thermal Response during Work Tasks-A Systematic Review.

Int J Environ Res Public Health 2020 10 9;17(20). Epub 2020 Oct 9.

INAIL-Department of Occupational and Environmental Medicine, Epidemiology and Hygiene-Laboratory of Ergonomics and Physiology, via Fontana Candida 1, 00078 Monte Porzio Catone, Rome, Italy.

Background: New wearable assistive devices (exoskeletons) have been developed for assisting people during work activity or rehabilitation. Although exoskeletons have been introduced into different occupational fields in an attempt to reduce the risk of work-related musculoskeletal disorders, the effectiveness of their use in workplaces still needs to be investigated. This systematic review focused on the effects of upper-body exoskeletons (UBEs) on human metabolic cost and thermophysiological response during upper-body work tasks.

Methods: articles published until 22 September 2020 were selected from Scopus, Web of Science, and PubMed for eligibility and the potential risk of bias was assessed.

Results: Nine articles resulted in being eligible for the metabolic aspects, and none for the thermal analysis. All the studies were based on comparisons between conditions with and without exoskeletons and considered a total of 94 participants (mainly males) performing tasks involving the trunk or overhead work, 7 back-support exoskeletons, and 1 upper-limb support exoskeleton. Eight studies found a significant reduction in the mean values of the metabolic or cardiorespiratory parameters considered and one found no differences.

Conclusions: The reduction found represents a preliminary finding that needs to be confirmed in a wider range of conditions, especially in workplaces, where work tasks show different characteristics and durations compared to those simulated in the laboratory. Future developments should investigate the dependence of metabolic cost on specific UBE design approaches during tasks involving the trunk and the possible statistical correlation between the metabolic cost and the surface ElectroMyoGraphy (sEMG) parameters. Finally, it could be interesting to investigate the effect of exoskeletons on the human thermophysiological response.
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http://dx.doi.org/10.3390/ijerph17207374DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7600262PMC
October 2020

Pelvic obliquity as a compensatory mechanism leading to lower energy recovery: Characterization among the types of prostheses in subjects with transfemoral amputation.

Gait Posture 2020 07 12;80:280-284. Epub 2020 Jun 12.

Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Polo Pontino, Via Franco Faggiana 1668, 04100, Latina, Italy; Movement Analysis Laboratory, Policlinico Italia, Piazza del Campidano, 6, 00162, Rome, Italy.

Background: Subjects with transfemoral amputation (TFA) show an asymmetric gait pattern associated with a decreased ability to recover mechanical energy and an increased metabolic cost of walking.

Research Question: This study aimed to identify the spatio-temporal and kinematic gait variables correlated with mechanical energy values in subjects with TFA and to observe the ability of the identified parameters to discriminate between TFA and controls according to the type of prosthesis.

Methods: The gait of 40 subjects with TFA was evaluated with a motion 3-D optoelectronic system. Nine subjects wore a mechanical prosthesis (TFAm), seventeen a C-Leg prosthesis (TFAc), and fourteen a Genium prosthesis (TFAg). Spatio-temporal and pelvic kinematic parameters were measured. Energy recovery was measured relative to the whole-body center of mass (CoM) kinematics as the fraction of mechanical energy recovered during each walking step (R-step). Correlation tests and multiple linear regression analyses were used to evaluate the correlation and association between kinematic and energy variables, respectively. Receiver operating characteristics curves were plotted to assess the ability of the correlated parameter to distinguish subjects with TFA from controls, and optimal cutoff point values were calculated according to the type of prosthesis.

Results: Among the spatio-temporal and kinematic parameters correlated to R-step, only pelvic obliquity of the prosthetic side was significantly associated with R-step. It showed an excellent ability to discriminate between TFA and controls. Furthermore, pelvic obliquity showed an excellent discriminative ability in identifying TFAm and TFAc and a good discriminative ability in identifying TFAg from controls.

Significance: Pelvic obliquity plays an important role in energy recovery during gait for subjects using prosthetics. This information might be exploited to monitor the adaptation of subjects with TFA to prosthetic devices, to lower the energetic cost of walking potentially, and to reduce the long-term risks of secondary physical complications in prosthetic users.
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http://dx.doi.org/10.1016/j.gaitpost.2020.06.013DOI Listing
July 2020

Impairment of Global Lower Limb Muscle Coactivation During Walking in Cerebellar Ataxias.

Cerebellum 2020 Aug;19(4):583-596

Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy.

The aim of this study was to investigate the time-varying multi-muscle coactivation function (TMCf) in the lower limbs during gait and its relationship with the biomechanical and clinical features of patients with cerebellar ataxia. A total of 23 patients with degenerative cerebellar ataxia (16 with spinocerebellar ataxia, 7 with adult-onset ataxia of unknown etiology) and 23 age-, sex-, and speed-matched controls were investigated. The disease severity was assessed using the Scale for the Assessment and Rating of Ataxia (SARA) in all patients. During walking, simultaneous acquisition of kinematic, kinetic, and electromyography data was performed using a motion analysis system. The coactivation was processed throughout the gait cycle using the TMCf, and the following parameters were measured: synthetic coactivation index, full width at half maximum, and center of activity. Spatiotemporal (walking speed, stance duration, swing duration, first and second double-support durations, step length, step width, stride length, Center of Mass displacement), kinetic (vertical component of GRFs), and energy consumption (total energy consumption and mechanical energy recovered) parameters were also measured. The coactivation variables were compared between patients and controls and were correlated with both clinical and gait variables. A significantly increased global TMCf was found in patients compared with controls. In addition, the patients showed a significant shift of the center of activity toward the initial contact and a significant reduction in energy recovery. All coactivation parameters were negatively correlated with gait speed, whereas the coactivation index and center of activity were positively correlated with both center-of-mass mediolateral displacement values and SARA scores. Our findings suggest that patients use global coactivation as a compensatory mechanism during the earliest and most challenging subphase (loading response) of the gait cycle to reduce the lateral body sway, thus improving gait stability at the expense of effective energy recovery. This information could be helpful in optimizing rehabilitative treatment aimed at improving lower limb muscle control during gait in patients with cerebella ataxia.
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http://dx.doi.org/10.1007/s12311-020-01142-6DOI Listing
August 2020

Global Muscle Coactivation of the Sound Limb in Gait of People with Transfemoral and Transtibial Amputation.

Sensors (Basel) 2020 Apr 29;20(9). Epub 2020 Apr 29.

Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL, Monte Porzio Catone, 00185 Rome, Italy.

The aim of this study was to analyze the effect of the level of amputation and various prosthetic devices on the muscle activation of the sound limb in people with unilateral transfemoral and transtibial amputation. We calculated the global coactivation of 12 muscles using the time-varying multimuscle coactivation function method in 37 subjects with unilateral transfemoral amputation (10, 16, and 11 with mechanical, electronic, and bionic prostheses, respectively), 11 subjects with transtibial amputation, and 22 healthy subjects representing the control group. The results highlighted that people with amputation had a global coactivation temporal profile similar to that of healthy subjects. However, amputation increased the level of the simultaneous activation of many muscles during the loading response and push-off phases of the gait cycle and decreased it in the midstance and swing subphases. This increased coactivation probably plays a role in prosthetic gait asymmetry and energy consumption. Furthermore, people with amputation and wearing electronic prosthesis showed lower global coactivation when compared with people wearing mechanical and bionic prostheses. These findings suggest that the global lower limb coactivation behavior can be a useful tool to analyze the motor control strategies adopted and the ability to adapt to the prosthetic device.
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http://dx.doi.org/10.3390/s20092543DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7249183PMC
April 2020

Modular motor control of the sound limb in gait of people with trans-femoral amputation.

J Neuroeng Rehabil 2019 11 6;16(1):132. Epub 2019 Nov 6.

Department of Engineering, University Roma TRE, Roma, Italy.

Background: The above-knee amputation of a lower limb is a severe impairment that affects significantly the ability to walk; considering this, a complex adaptation strategy at the neuromuscular level is needed in order to be able to move safely with a prosthetic knee. In literature, it has been demonstrated that muscle activity during walking can be described via the activation of a small set of muscle synergies. The analysis of the composition and the time activation profiles of such synergies have been found to be a valid tool for the description of the motor control schemes in pathological subjects.

Methods: In this study, we used muscle synergy analysis techniques to characterize the differences in the modular motor control schemes between a population of 14 people with trans-femoral amputation and 12 healthy subjects walking at two different (slow and normal self-selected) speeds. Muscle synergies were extracted from a 12 lower-limb muscles sEMG recording via non-negative matrix factorization. Equivalence of the synergy vectors was quantified by a cross-validation procedure, while differences in terms of time activation coefficients were evaluated through the analysis of the activity in the different gait sub-phases.

Results: Four synergies were able to reconstruct the muscle activity in all subjects. The spatial component of the synergy vectors did not change in all the analysed populations, while differences were present in the activity during the sound limb's stance phase. Main features of people with trans-femoral amputation's muscle synergy recruitment are a prolonged activation of the module composed of calf muscles and an additional activity of the hamstrings' module before and after the prosthetic heel strike.

Conclusions: Synergy-based results highlight how, although the complexity and the spatial organization of motor control schemes are the same found in healthy subjects, substantial differences are present in the synergies' recruitment of people with trans femoral amputation. In particular, the most critical task during the gait cycle is the weight transfer from the sound limb to the prosthetic one. Future studies will integrate these results with the dynamics of movement, aiming to a complete neuro-mechanical characterization of people with trans-femoral amputation's walking strategies that can be used to improve the rehabilitation therapies.
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http://dx.doi.org/10.1186/s12984-019-0616-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6836453PMC
November 2019

Progressive Modular Rebalancing System and Visual Cueing for Gait Rehabilitation in Parkinson's Disease: A Pilot, Randomized, Controlled Trial With Crossover.

Front Neurol 2019 29;10:902. Epub 2019 Aug 29.

Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Rome, Italy.

The progressive modular rebalancing (PMR) system is a comprehensive rehabilitation approach derived from proprioceptive neuromuscular facilitation principles. PMR training encourages focus on trunk and proximal muscle function through direct perception, strength, and stretching exercises and emphasizes bi-articular muscle function in the improvement of gait performance. Sensory cueing, such as visual cues (VC), is one of the more established techniques for gait rehabilitation in PD. In this study, we propose PMR combined with VC for improving gait performance, balance, and trunk control during gait in patients with PD. Our assumption herein was that the effect of VC may add to improved motor performance induced by the PMR treatment. The primary aim of this study was to evaluate whether the PMR system plus VC was a more effective treatment option than standard physiotherapy in improving gait function in patients with PD. The secondary aim of the study was to evaluate the effect of this treatment on motor function severity. Two-center, randomized, controlled, observer-blind, crossover study with a 4-month washout period. Forty individuals with idiopathic PD in Hoehn and Yahr stages 1-4. Eight-week rehabilitation programs consisting of PMR plus VC (treatment A) and conventional physiotherapy (treatment B). Spatiotemporal gait parameters, joint kinematics, and trunk kinematics. UPDRS-III scale scores. The rehabilitation program was well-tolerated by individuals with PD and most participants showed improvements in gait variables and UPDRS-III scores with both treatments. However, patients who received PMR with VC showed better results in gait function with regard to gait performance (increased step length, gait speed, and joint kinematics), gait balance (increased step width and double support duration), and trunk control (increased trunk motion) than those receiving conventional physiotherapy. While crossover results revealed some differences in primary outcomes, only 37.5% of patients crossed over between the groups. As a result, our findings should be interpreted cautiously. The PMR plus VC program could be used to improve gait function and severity motor of motor deficit in individuals with PD. : www.ClinicalTrials.gov, identifier NCT03346265.
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http://dx.doi.org/10.3389/fneur.2019.00902DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6730596PMC
August 2019

Prediction of Responsiveness of Gait Variables to Rehabilitation Training in Parkinson's Disease.

Front Neurol 2019 2;10:826. Epub 2019 Aug 2.

Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Rome, Italy.

Gait disorders represent one of the most disabling features of Parkinson's disease, which may benefit from rehabilitation. No consistent evidence exists about which gait biomechanical factors can be modified by rehabilitation and which clinical characteristic can predict rehabilitation-induced improvements. The aims of the study were as follows: (i) to recognize the gait parameters modifiable by a short-term rehabilitation program; (ii) to evaluate the gait parameters that can normalize after rehabilitation; and (iii) to identify clinical variables predicting improvements in gait function after rehabilitation. Thirty-six patients affected by idiopathic Parkinson's disease in Hoehn-Yahr stage 1-3 and 22 healthy controls were included in the study. Both clinical and instrumental (gait analysis) evaluations were performed before and after a 10-weeks rehabilitation treatment. Time-distance parameters, lower limb joint, and trunk kinematics were measured. At baseline evaluation with matched speed, almost all gait parameters were significantly different between patients and healthy controls. After the 10-weeks rehabilitation, most gait parameters improved, and spatial asymmetry and trunk rotation normalized. Multiple linear regression of gender combined with Unified Parkinson's Disease Rating Scale-III predicted both ΔSpeed and ΔStep length of both sides; gender combined with Unified Parkinson's Disease Rating Scale-II predicted ΔCadence; age combined with Hoehn-Yahr score and disease duration predicted Δtrunk rotation range of motion. Impaired gait parameters are susceptible to improvement by rehabilitation, and younger men with Parkinson's disease who are less severely affected and at early disease stage are more susceptible to improvements in gait function after a 10-weeks rehabilitation program.
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http://dx.doi.org/10.3389/fneur.2019.00826DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6688512PMC
August 2019

Common and specific gait patterns in people with varying anatomical levels of lower limb amputation and different prosthetic components.

Hum Mov Sci 2019 Mar 16;66:9-21. Epub 2019 Mar 16.

Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL, Via Fontana Candida 1, 00078 Monte Porzio Catone, Rome, Italy.

The present study's aim was to identify the kinematic and kinetic gait patterns and to measure the energy consumption in people with amputation according to both the anatomical level of amputation and the type of prosthetic components in comparison with a control group matched for the gait speed. Fifteen subjects with unilateral transtibial amputation (TTA), forty with unilateral transfemoral amputation (TFA) (9 with mechanical, 17 with CLeg and 14 with Genium prosthesis) and forty healthy subjects were recruited. We computed the time-distance gait parameters; the range of angular motion (RoM) at hip, knee and ankle joints, and at the trunk and pelvis; the values of the 2 peaks of vertical force curve; the full width at half maximum (FWHM) and center of activity (CoA) of vertical force; the mechanical behavior in terms of energy recovery (R-step) and energy consumption. The main results were: i) both TTA and TFA show a common gait pattern characterized by a symmetric increase of step length, step width, double support duration, pelvic obliquity, trunk lateral bending and trunk rotation RoMs compared to control groups. They show also an asymmetric increase of stance duration and of Peak1 in non-amputated side and a decrease of ankle RoM in amputated side; ii) only TFA show a specific gait pattern, depending on the level of amputation, characterized by a symmetric reduction of R-step and an asymmetric decrease of stance duration, CoA and FWHM and an increase of Peak1 in the amputated side and of hip and knee RoM, CoA and FWHM in the non-amputated side; iii) people with amputation with Genium prosthesis show a longer step length and increased hip and knee RoMs compared to people with amputation with mechanical prosthesis who conversely show an increased pelvic obliquity: these are specific gait patterns depending of the type of prosthesis. In conclusion, we identified both common and specific gait patterns in people with amputation, either regardless of, or according to their level of amputation and the type of prosthetic component.
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http://dx.doi.org/10.1016/j.humov.2019.03.008DOI Listing
March 2019

Erratum: Alberto, R. et al., Wearable Monitoring Devices for Biomechanical Risk Assessment at Work: Current Status and Future Challenges-A Systematic Review. Int. J. Environ. Res. Public Health 2018, 15, 2001.

Int J Environ Res Public Health 2018 11 16;15(11). Epub 2018 Nov 16.

Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL, Via Fontana Candida 1, Monte Porzio Catone, 00078 Rome, Italy.

Due to an error during production, the first author's name of the published paper [...].
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http://dx.doi.org/10.3390/ijerph15112569DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6265804PMC
November 2018

Wearable Monitoring Devices for Biomechanical Risk Assessment at Work: Current Status and Future Challenges-A Systematic Review.

Int J Environ Res Public Health 2018 09 13;15(9). Epub 2018 Sep 13.

Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL, Via Fontana Candida 1, Monte Porzio Catone, 00078 Rome, Italy.

: In order to reduce the risk of work-related musculoskeletal disorders (WMSDs) several methods have been developed, accepted by the international literature and used in the workplace. The purpose of this systematic review was to describe recent implementations of wearable sensors for quantitative instrumental-based biomechanical risk assessments in prevention of WMSDs. : Articles written until 7 May 2018 were selected from PubMed, Scopus, Google Scholar and Web of Science using specific keywords. : Instrumental approaches based on inertial measurement units and sEMG sensors have been used for direct evaluations to classify lifting tasks into low and high risk categories. Wearable sensors have also been used for direct instrumental evaluations in handling of low loads at high frequency activities by using the local myoelectric manifestation of muscle fatigue estimation. In the field of the rating of standard methods, on-body wireless sensors network-based approaches for real-time ergonomic assessment in industrial manufacturing have been proposed. : Few studies foresee the use of wearable technologies for biomechanical risk assessment although the requirement to obtain increasingly quantitative evaluations, the recent miniaturization process and the need to follow a constantly evolving manual handling scenario is prompting their use.
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http://dx.doi.org/10.3390/ijerph15092001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6163390PMC
September 2018

Neurophysiology of gait.

Handb Clin Neurol 2018 ;154:299-303

Department of Medical and Surgical Sciences and Biotechnologies, University of Rome Sapienza, Latina, Italy.

Beyond the classic clinical description, recent studies have quantitatively evaluated gait and balance dysfunction in cerebellar ataxias by means of modern motion analysis systems. These systems have the aim of clearly and quantitatively describing the differences, with respect to healthy subjects, in kinematic, kinetic, and surface electromyography variables, establishing the basis for a rehabilitation strategy and assessing its efficacy. The main findings which characterize the gait pattern of cerebellar patients are: increased step width, reduced ankle joint range of motion with increased coactivation of the antagonist muscles, and increased stride-to-stride variability. Whereas the former is a compensatory strategy adopted by patients to keep the center of mass within the base of support, the latter indicates the inability of patients to maintain dynamic balance through a regular walking pattern and may reflect the primary deficit directly related to cerebellar dysfunction and the consequent lack of muscle coordination during walking. Moreover, during the course of the disease, with the progressive loss of walking autonomy, step length, and lower-limb joint range of motion are drastically reduced. As to the joint coordination defect, abnormal intralimb joint coordination during walking, in terms of both joint kinematics and interaction torques, has been reported in several studies. Furthermore, patients with cerebellar ataxia show a poor intersegmental coordination, with a chaotic coordinative behavior between trunk and hip, leading to increased upper-body oscillations that affect gait performance and stability, sustaining a vicious circle that transforms the upper body into a generator of perturbations. The use of motion analysis laboratories allows a deeper segmental and global characterization of walking impairment in these patients and can shed light on the nature of both the primary specific gait disorder and compensatory mechanisms. Such deeper understanding might reasonably represent a valid prerequisite for establishing better-targeted rehabilitation strategies.
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http://dx.doi.org/10.1016/B978-0-444-63956-1.00018-7DOI Listing
September 2018

Biomechanical characterization of the Junzuki karate punch: indexes of performance.

Eur J Sport Sci 2018 Jul 3;18(6):796-805. Epub 2018 Apr 3.

b Rehabilitation Centre , Policlinico Italia , Rome , Italy.

The aims of this study were: (i) to determine kinematic, kinetic, and electromyographic characteristics of Junzuki karate punch in professional karate athletes; (ii) to identify biomechanical parameters that correlate with punch force and lead to a higher punching performance; (iii) to verify the presence of muscle co-activation in the upper limb, trunk, and lower limb muscles. Data were collected from nine experienced karatekas from the Accademia Italiana Karate e Arti Marziali during the execution of the specific punch. Mean punch forces (181.2 N) delivered to the target, the range of motion of both right and left knees (1.13 and 0.82 rad) and right elbow (1.49 rad) joints, and the angles at impact (knee: 0.81 and 0.91 rad; elbow: 1.19 rad) in the sagittal plane were computed. Furthermore, the trunk rotational angular acceleration (63.1 rads), force related to the lower limbs (550.2 and 425.1 N), and co-activation index for the upper limb (36.1% and 34.7%), trunk (24.5% and 16%), and lower limbs (16.0% and 16.1%) muscles were evaluated bilaterally. Significant positive correlations were found between the punch force and both right and left knee flexion at the instant of impact and right and left leg force. Significant negative correlation was found between the punch force and maximum trunk angular acceleration. Significant differences (p = .03) in the co-activation index among the upper limb, trunk, and lower limbs muscles highlighted a rostro-caudal gradient on both body sides. This research could be of use to performers and coaches when considering training preparations.
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http://dx.doi.org/10.1080/17461391.2018.1455899DOI Listing
July 2018

Dataset on gait patterns in degenerative neurological diseases.

Data Brief 2018 Feb 12;16:806-816. Epub 2017 Dec 12.

Department of Mechanical and Aerospace Engineering, "Sapienza" University of Rome, Via Eudossiana 18 - 00184 Roma, Italy.

We collected the gait parameters and lower limb joint kinematics of patients with three different types of primary degenerative neurological diseases: (i) cerebellar ataxia (19 patients), (ii) hereditary spastic paraparesis (26 patients), and (iii) Parkinson's disease (32 patients). Sixty-five gender-age matched healthy subjects were enrolled as control group. An optoelectronic motion analysis system was used to measure time-distance parameters and lower limb joint kinematics during gait in both patients and healthy controls.
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http://dx.doi.org/10.1016/j.dib.2017.12.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5773445PMC
February 2018

Identification of specific gait patterns in patients with cerebellar ataxia, spastic paraplegia, and Parkinson's disease: A non-hierarchical cluster analysis.

Hum Mov Sci 2018 Feb 28;57:267-279. Epub 2017 Sep 28.

Department of Mechanical and Aerospace Engineering, "Sapienza" University of Rome, Via Eudossiana 18, 00184 Roma, Italy.

Background: Patients with degenerative neurological diseases such as cerebellar ataxia, spastic paraplegia, and Parkinson's disease often display progressive gait function decline that inexorably impacts their autonomy and quality of life. Therefore, considering the related social and economic costs, one of the most important areas of intervention in neurorehabilitation should be the treatment of gait abnormalities. This study aims to determine whether an entire dataset of gait parameters recorded in patients with degenerative neurological diseases can be clustered into homogeneous groups distinct from each other and from healthy subjects. Patients affected by three different types of primary degenerative neurological diseases were studied. These diseases were: i) cerebellar ataxia (28 patients), ii) hereditary spastic paraplegia (31 patients), and iii) Parkinson's disease (70 patients). Sixty-five gender-age-matched healthy subjects were enrolled as a control group. An optoelectronic motion analysis system was used to measure time-distance parameters and lower limb joint kinematics during gait in both patients and healthy controls. When clustering single parameters, step width and ankle joint range of motion (RoM) in the sagittal plane differentiated cerebellar ataxia group from the other groups. When clustering sets of two, three, or four parameters, several pairs, triples, and quadruples of clusters differentiated the cerebellar ataxia group from the other groups. Interestingly, the ankle joint RoM parameter was present in 100% of the clusters and the step width in approximately 50% of clusters. In addition, in almost all clusters, patients with cerebellar ataxia showed the lowest ankle joint RoM and the largest step width values compared to healthy controls, patients with hereditary spastic paraplegia, and Parkinson's disease subjects. This study identified several clusters reflecting specific gait patterns in patients with degenerative neurological diseases. In particular, the specific gait pattern formed by the increased step width, reduced ankle joint RoM, and increased gait variability, can differentiate patients with cerebellar ataxia from healthy subjects and patients with spastic paraplegia or Parkinson's disease. These abnormal parameters may be adopted as sensitive tools for evaluating the effect of pharmacological and rehabilitative treatments.
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http://dx.doi.org/10.1016/j.humov.2017.09.005DOI Listing
February 2018

Myoelectric manifestation of muscle fatigue in repetitive work detected by means of miniaturized sEMG sensors.

Int J Occup Saf Ergon 2018 Sep 25;24(3):464-474. Epub 2017 Sep 25.

a Department of Occupational and Environmental Medicine, Epidemiology and Hygiene , INAIL , Italy.

Upper limb work-related musculoskeletal disorders have a 12-month prevalence ranging from 12 to 41% worldwide and can be partly caused by handling low loads at high frequency. The association between the myoelectric manifestation of elbow flexor muscle fatigue and occupational physical demand has never been investigated. It was hypothesized that an elbow flexor muscle fatigue index could be a valid risk indicator in handling low loads at high frequency. This study aims to measure the myoelectric manifestation of muscle fatigue of the three elbow flexor muscles during the execution of the work tasks in different risk conditions. Fifteen right-handed healthy adults were screened using a movement analysis laboratory consisting of optoelectronic, dynamometer and surface electromyographic systems. The main result indicates that the fatigue index calculated from the brachioradialis is sensitive to the interaction among risk classes, session and gender, and above all it is sensitive to the risk classes.
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http://dx.doi.org/10.1080/10803548.2017.1357867DOI Listing
September 2018

Mechanical lifting energy consumption in work activities designed by means of the "revised NIOSH lifting equation".

Ind Health 2017 Oct 7;55(5):444-454. Epub 2017 Aug 7.

Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL, Italy.

The aims of the present work were: to calculate lifting energy consumption (LEC) in work activities designed to have a growing lifting index (LI) by means of revised NIOSH lifting equation; to evaluate the relationship between LEC and forces at the L-S joint. The kinematic and kinetic data of 20 workers were recorded during the execution of lifting tasks in three conditions. We computed kinetic, potential and mechanical energy and the corresponding LEC by considering three different centers of mass of: 1) the load (CoM); 2) the multi-segment upper body model and load together (CoM); 3) the whole body and load together (CoM). We also estimated compression and shear forces. Results shows that LEC calculated for CoM and CoM grew significantly with the LI and that all the lifting condition pairs are discriminated. The correlation analysis highlighted a relationship between LEC and forces that determine injuries at the L-S joint.
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http://dx.doi.org/10.2486/indhealth.2017-0075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5633360PMC
October 2017

Increased lower limb muscle coactivation reduces gait performance and increases metabolic cost in patients with hereditary spastic paraparesis.

Clin Biomech (Bristol, Avon) 2017 Oct 29;48:63-72. Epub 2017 Jul 29.

Rehabilitation Centre, Policlinico Italia, Piazza del Campidano 6, 00162 Rome, Italy; Department of Medico-Surgical Sciences and Biotechnologies, University of Rome Sapienza, Via Faggiana 34, 04100 Latina, Italy. Electronic address:

Background: The aim of this study was to investigate the lower limb muscle coactivation and its relationship with muscles spasticity, gait performance, and metabolic cost in patients with hereditary spastic paraparesis.

Methods: Kinematic, kinetic, electromyographic and energetic parameters of 23 patients and 23 controls were evaluated by computerized gait analysis system. We computed ankle and knee antagonist muscle coactivation indexes throughout the gait cycle and during the subphases of gait. Energy consumption and energy recovery were measured as well. In addition to the correlation analysis between coactivation indexes and clinical variables, correlations between coactivation indexes and time-distance, kinematic, kinetic, and energetic parameters were estimated.

Findings: Increased coactivity indexes of both knee and ankle muscles throughout the gait cycle and during the subphases of gait were observed in patients compared with controls. Energetic parameters were significantly higher in patients than in controls. Both knee and ankle muscle coactivation indexes were positively correlated with knee and ankle spasticity (Ashworth score), respectively. Knee and ankle muscle coactivation indexes were both positively correlated with energy consumption and both negatively correlated with energy recovery.

Interpretation: Positive correlations between the Ashworth score and lower limb muscle coactivation suggest that abnormal lower limb muscle coactivation in patients with hereditary spastic paraparesis reflects a primary deficit linked to lower limb spasticity. Furthermore, these abnormalities influence the energetic mechanisms during walking. Identifying excessive muscle coactivation may be helpful in individuating the rehabilitative treatments and designing specific orthosis to restrain spasticity.
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http://dx.doi.org/10.1016/j.clinbiomech.2017.07.013DOI Listing
October 2017

Harmony as a convergence attractor that minimizes the energy expenditure and variability in physiological gait and the loss of harmony in cerebellar ataxia.

Clin Biomech (Bristol, Avon) 2017 Oct 5;48:15-23. Epub 2017 Jul 5.

INAIL, Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, Via Fontana Candida 1, 00040 Monte Porzio Catone, Italy. Electronic address:

Background: The harmony of the human gait was recently found to be related to the golden ratio value (ϕ). The ratio between the duration of the stance and that of the swing phases of a gait cycle was in fact found to be close to ϕ, which implies that, because of the fractal property of autosimilarity of that number, the gait ratios stride/stance, stance/swing, swing/double support, were not significantly different from one another. We studied a group of patients with cerebellar ataxia to investigate how the differences between their gait ratios and the golden ratio are related to efficiency and stability of their gait, assessed by energy expenditure and stride-to-stride variability, respectively.

Methods: The gait of 28 patients who were affected by degenerative cerebellar ataxia and of 28 healthy controls was studied using a stereophotogrammetric system. The above mentioned gait ratios, the energy expenditure estimated using the pelvis reconstructed method and the gait variability in terms of the stride length were computed, and their relationships were analyzed. Matching procedures have also been used to avoid multicollinearity biases.

Findings: The gait ratio values of the patients were farther from the controls (and hence from ϕ), even in speed matched conditions (P=0.011, Cohen's D=0.76), but not when the variability and energy expenditure were matched between the two groups (Cohen's D=0.49). In patients with cerebellar ataxia, the farther the stance-swing ratio was from ϕ, the larger the total mechanical work (R=0.64). Further, a significant positive correlation was observed between the difference of the gait ratio from the golden ratio and the severity of the disease (R=0.421, P=0.026).

Interpretation: Harmony of gait appears to be a benchmark of physiological gait leading to physiological energy recovery and gait reliability. Neurorehabilitation of patients with ataxia might benefit from the restoration of harmony of their locomotor patterns.
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http://dx.doi.org/10.1016/j.clinbiomech.2017.07.001DOI Listing
October 2017

Use of dynamic movement orthoses to improve gait stability and trunk control in ataxic patients.

Eur J Phys Rehabil Med 2017 Oct 19;53(5):735-743. Epub 2017 Jun 19.

Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University, Polo Pontino, Latina, Italy.

Background: Patients with cerebellar ataxia show increased upper body movements, which have an impact on balance and walking.

Aim: In this study, we investigated the effect of using dynamic movement orthoses (DMO), designed as elastic suits, on trunk motion and gait parameters.

Design: Longitudinal uncontrolled study.

Setting: Outpatient rehabilitation unit.

Population: Eleven patients (7 men, 4 women; mean age: 49.9±9.5 years) with degenerative cerebellar ataxia were enrolled in this study.

Methods: Linear overground gait of patients was recorded by means of an optoelectronic gait analysis system before DMO use (DMO-) and during DMO use (DMO+). Time-distance parameters, lower limb joint kinematics, body sway, trunk oscillations, and gait variability (coefficient of variation [CV]) were recorded. Patient satisfaction with DMO device was measured using Quebec user evaluation of satisfaction with assistive technology.

Results: When using the DMO, patients showed a significant decrease in stance phase duration, double support phase duration, swing phase CV, pelvic range of motion (ROM), body sway, and trunk ROMs. A significant increase was observed in the swing phase duration and knee joint ROM. Out of 11 patients, 10 were either quite satisfied (8 points) or very satisfied (2 points) with the assistive device.

Conclusions: The DMO reduce the upper body motion and in improve balance-related gait parameters.

Clinical Rehabilitation Impact: We propose use of DMO as an assistive/rehabilitative device in the neurorehabilitation of cerebellar ataxia to improve the trunk control and gait stability. DMO may be considered a prototype that can be modified in terms of material characteristics, textile layers, elastic components, and diagonal and lateral seams.
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http://dx.doi.org/10.23736/S1973-9087.17.04480-XDOI Listing
October 2017

Progression of Gait Ataxia in Patients with Degenerative Cerebellar Disorders: a 4-Year Follow-Up Study.

Cerebellum 2017 06;16(3):629-637

Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Via Faggiana 1668, 40100, Latina, Italy.

In the present study, the progression of gait impairment in a group of patients with primary degenerative cerebellar ataxias was observed over a period of 4 years. A total of 30 patients underwent an initial gait analysis study, and thereafter only 12 were evaluated because they completed the 2- and 4-year follow-up evaluations. Time-distance parameters, trunk and joint range of motion (RoM), and variability parameters (e.g., coefficients of variation) were measured at the baseline and at each follow-up evaluation. The scale for the assessment and rating of ataxia (SARA) was used to evaluate disease severity. We found a significant increase in the SARA score at both the 2- and 4-year follow-up evaluations. Almost all the gait variables changed significantly only at the 4-year follow-up. Particularly, we found a significant decrease in the step length and in the hip, knee, and ankle joint RoM values and noted a significant increase in the trunk rotation RoM and stride-to-stride and step length variability. Furthermore, a significant difference in ankle joint RoM was found between spinocerebellar ataxia and sporadic adult-onset ataxia patients, with the value being lower in the former group of patients. Our findings suggest that patients with degenerative cerebellar ataxias exhibit gait decline after 4 years from the baseline. Moreover, patients try to maintain an effective gait by adopting different compensatory mechanisms during the course of the disease in spite of disease progression.
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http://dx.doi.org/10.1007/s12311-016-0837-2DOI Listing
June 2017

Gait Patterns in Patients with Hereditary Spastic Paraparesis.

PLoS One 2016 12;11(10):e0164623. Epub 2016 Oct 12.

Department of Medico-Surgical Sciences and Biotechnologies, University of Rome Sapienza, Latina, Italy.

Background: Spastic gait is a key feature in patients with hereditary spastic paraparesis, but the gait characterization and the relationship between the gait impairment and clinical characteristics have not been investigated.

Objectives: To describe the gait patterns in hereditary spastic paraparesis and to identify subgroups of patients according to specific kinematic features of walking.

Methods: We evaluated fifty patients by computerized gait analysis and compared them to healthy participants. We computed time-distance parameters of walking and the range of angular motion at hip, knee, and ankle joints, and at the trunk and pelvis. Lower limb joint moments and muscle co-activation values were also evaluated.

Results: We identified three distinct subgroups of patients based on the range of motion values. Subgroup one was characterized by reduced hip, knee, and ankle joint range of motion. These patients were the most severely affected from a clinical standpoint, had the highest spasticity, and walked at the slowest speed. Subgroup three was characterized by an increased hip joint range of motion, but knee and ankle joint range of motion values close to control values. These patients were the most mildly affected and had the highest walking speed. Finally, subgroup two showed reduced knee and ankle joint range of motion, and hip range of motion values close to control values. Disease severity and gait speed in subgroup two were between those of subgroups one and three.

Conclusions: We identified three distinctive gait patterns in patients with hereditary spastic paraparesis that correlated robustly with clinical data. Distinguishing specific features in the gait patterns of these patients may help tailor pharmacological and rehabilitative treatments and may help evaluate therapeutic effects over time.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0164623PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5061421PMC
May 2017

Perceptive rehabilitation and trunk posture alignment in patients with Parkinson disease: a single blind randomized controlled trial.

Eur J Phys Rehabil Med 2016 Dec 12;52(6):799-809. Epub 2016 May 12.

Unit of Physical and Rehabilitation Medicine, Department of Medicine, Campus Bio-Medico University, Rome, Italy.

Background: Recent studies aimed to evaluate the potential effects of perceptive rehabilitation in Parkinson Disease reporting promising preliminary results for postural balance and pain symptoms. To date, no randomized controlled trial was carried out to compare the effects of perceptive rehabilitation and conventional treatment in patients with Parkinson Disease.

Aim: To evaluate whether a perceptive rehabilitation treatment could be more effective than a conventional physical therapy program in improving postural control and gait pattern in patients with Parkinson Disease.

Design: Single blind, randomized controlled trial.

Setting: Department of Physical and Rehabilitation Medicine of a University Hospital.

Population: Twenty outpatients affected by idiopathic Parkinson Disease at Hoehn and Yahr stage ≤3.

Methods: Recruited patients were divided into two groups: the first one underwent individual treatment with Surfaces for Perceptive Rehabilitation (Su-Per), consisting of rigid wood surfaces supporting deformable latex cones of various dimensions, and the second one received conventional group physical therapy treatment. Each patient underwent a training program consisting of ten, 45-minute sessions, three days a week for 4 consecutive weeks. Each subject was evaluated before treatment, immediately after treatment and at one month of follow-up, by an optoelectronic stereophotogrammetric system for gait and posture analysis, and by a computerized platform for stabilometric assessment.

Results: Kyphosis angle decreased after ten sessions of perceptive rehabilitation, thus showing a substantial difference with respect to the control group. No significant differences were found as for gait parameters (cadence, gait speed and stride length) within Su-Per group and between groups. Parameters of static and dynamic evaluation on stabilometric platform failed to demonstrate any statistically relevant difference both within-groups and between-groups.

Conclusions: Perceptive training may help patients affected by Parkinson Disease into restoring a correct midline perception and, in turn, to improve postural control.

Clinical Rehabilitation Impact: Perceptive surfaces represent an alternative to conventional rehabilitation of postural disorders in Parkinson Disease. Further studies are needed to determine if the association of perceptive treatment and active motor training would be useful in improving also gait dexterity.
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December 2016

Local Stability of the Trunk in Patients with Degenerative Cerebellar Ataxia During Walking.

Cerebellum 2017 02;16(1):26-33

Movement Analysis LAB, Rehabilitation Centre Policlinico Italia, Piazza del Campidano 6, 00162, Rome, Italy.

This study aims to evaluate trunk local stability in a group of patients with degenerative primary cerebellar ataxia and to correlate it with spatio-temporal parameters, clinical variables, and history of falls. Sixteen patients affected by degenerative cerebellar ataxia and 16 gender- and age-matched healthy adults were studied by means of an inertial sensor to measure trunk kinematics and spatio-temporal parameters during over-ground walking. Trunk local dynamic stability was quantified by the maximum Lyapunov exponent with short data series of the acceleration data. According to this index, low values indicate more stable trunk dynamics, while high values denote less stable trunk dynamics. Disease severity was assessed by means of International Cooperative Ataxia Rating Scale (ICARS) according to which higher values correspond to more severe disease, while lower values correspond to less severe disease.Patients displayed a higher short-term maximum Lyapunov exponent than controls in all three spatial planes, which was correlated with the age, onset of the disease, and history of falls. Furthermore, the maximum Lyapunov exponent was negatively correlated with ICARS balance, ICARS posture, and ICARS total scores.These findings indicate that trunk local stability during gait is lower in patients with cerebellar degenerative ataxia than that in healthy controls and that this may increase the risk of falls. Local dynamic stability of the trunk seems to be an important aspect in patients with ataxia and could be a useful tool in the evaluation of rehabilitative and pharmacological treatment outcomes.
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http://dx.doi.org/10.1007/s12311-016-0760-6DOI Listing
February 2017

Effect of 24-h continuous rotigotine treatment on stationary and non-stationary locomotion in de novo patients with Parkinson disease in an open-label uncontrolled study.

J Neurol 2015 Nov 25;262(11):2539-47. Epub 2015 Aug 25.

Department of Medico-Surgical Sciences and Biotechnologies, University of Rome Sapienza, Latina, Italy.

The aim of this study was to investigate the effect of a rotigotine transdermal patch on stationary and non-stationary locomotion in de novo Parkinson disease (PD) patients in an open-label uncontrolled study. A 3-D gait analysis system was used to investigate four different locomotor tasks: steady-state linear walking, gait initiation, gait termination and 180°-turning. A series of gait variables were measured for each locomotor task. PD patients who received rotigotine treatment (4-8 mg) displayed: (1) increased step length, gait speed, cadence and arm oscillations, and reduced double support duration and step asymmetry during steady-state linear gait; (2) increased initial step length during gait initiation; (3) increased final step length and gait speed, and decreased stability index during gait termination; (4) decreased duration of turning and head-pelvis delays during 180°-turning. The main finding that emerges from the present study is that the dopamine agonist rotigotine can improve various aspects of gait in de novo PD patients.
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http://dx.doi.org/10.1007/s00415-015-7883-4DOI Listing
November 2015

Modular organization of the head retraction responses elicited by electrical painful stimulation of the facial skin in humans.

Clin Neurophysiol 2015 Dec 19;126(12):2306-13. Epub 2015 Feb 19.

Department of Medical-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Corso della Repubblica 79, 04100 Latina, Italy. Electronic address:

Objective: To explore whether the trigeminocervical reflexes (TCRs) show a reflex receptive field organization in the brainstem.

Methods: The facial skin of 16 healthy subjects was electrically stimulated at nine sites reflecting the distribution of the three branches of the trigeminal nerve. The reflex-evoked EMG responses were measured bilaterally from the neck muscles and the head and neck kinematic reactions were detected.

Results: TCRs are site dependent. There was a vertical gradient in the magnitude of the reflex responses. EMG and kinematic reflexes were larger when evoked from ophthalmic and maxillary sites than from mandibular ones. The reflex responses exhibited a crossed right-left behavior. Stimulation of the lateral sites evoked larger reflex responses in the contralateral trapezium muscle as well as head rotation and neck bending away from the stimulated side.

Conclusion: This modular arrangement of the TCRs seems to be related to withdrawal strategies aimed at protecting the face from injuries, in accordance with the functional role that each group of muscles plays in head and neck motion.

Significance: It is likely that the CNS may exploit the neck muscle synergies revealed by the painful stimulation of the skin face in order to control the head and neck movements.
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http://dx.doi.org/10.1016/j.clinph.2015.01.029DOI Listing
December 2015

[The role of coactivation of the trunk musculature in evaluating biomechanical risk].

G Ital Med Lav Ergon 2014 Oct-Dec;36(4):347-50

Dipartimento di Medicina de Lavoro, INAIL, Roma

One of the mechanisms adopted by the central nervous system to stabilize the joints or the spine is muscle co-activation. Nevertheless during lifting tasks muscle co-activation increases spinal load. For co-activation assessment during 3 lifting tasks at increasing load levels we utilized a time-varying co-activation algorithm proposed by Rudolph in 2000. We found that Rudolph co-activation index grew with lifting index. The time-varying co-activation index gave a continuous measure of low back compression. A time-varying co-activation index could be of great interest in all conditions in which NIOSH equation is not applicable.
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March 2015