Paolo Gaffurini

Electromyogram and force fluctuation during different linearly varying isometric motor tasks

The purpose of this work was to verify if deviation from the mirror-like behaviour of the motor units activation strategy (MUAS) and de-activation strategy (MUDS) and the degree of the error of the motor control system, during consecutive linearly increasing-decreasing isometric tension tasks, depend on the maximum reached tension and/or on the rate of tension changes. In 12 male subjects the surface EMG and force produced by the first dorsal interosseus activity were recorded during two (a and b) trapezoid isometric contractions with different plateau (a: 50% maximal voluntary contraction (MVC) and b: 100% MVC) and rate of tension changes (a: 6.7% MVC/s and b: 13.3% MVC/s) during up-going (UGR) and down-going (DGR) ramps. Ten steps (ST) 6s long at 5, 10, 20, 30, 40, 50, 60, 70, 80 and 90% MVC were also recorded. The root mean square (RMS) and mean frequency (MF) from EMG and the relative error of actual force output with respect to the target (% ERR) were computed. The EMG-RMS/% MVC and EMG-MF/% MVC relationships were not overlapped when the ST and DGR as well as the UGR and DGR data were compared. The % ERR/% MVC relationships during a and b contractions differed from ST data only below 20% MVC. It can be concluded that MUAS and MUDS are not mirroring one each other because MU recruitment or de-recruitment threshold may be influenced by the maximum effort and by the % MVC/s of UGR and DGR. The role of MUs mechanical and/or central nervous system hysteresis on force decrement control is discussed.

Changes in skeletal muscle perfusion and spasticity in patients with poststroke hemiparesis treated by robotic assistance (Gloreha) of the hand

[Purpose] The purpose of this case series was to determine the effects of robot-assisted hand rehabilitation with a Gloreha device on skeletal muscle perfusion, spasticity, and motor function in subjects with poststroke hemiparesis. [Subjects and Methods] Seven patients, 2 women and 5 men (mean ± SD age: 60.5 ±6.3 years), with hemiparesis (>6 months poststroke), received passive mobilization of the hand with a Gloreha (Idrogenet, Italy), device (30 min per day; 3 sessions a week for 3 weeks). The outcome measures were the total hemoglobin profiles and tissue oxygenation index (TOI) in the muscle tissue evaluated through near-infrared spectroscopy. The Motricity Index and modified Ashworth Scale for upper limb muscles were used to assess mobility of the upper extremity. [Results] Robotic assistance reduced spasticity after the intervention by 68.6% in the upper limb. The Motricity Index was unchanged in these patients after treatment. Regarding changes in muscle perfusion, significant improvements were found in total hemoglobin. There were significant differences between the pre- and posttreatment modified Ashworth scale. [Conclusion] The present work provides novel evidence that robotic assistance of the hand induced changes in local muscle blood flow and oxygen supply, diminished spasticity, and decreased subject-reported symptoms of heaviness and stiffness in subjects with post-stroke hemiparesis.

Oxygen supply/uptake mismatch during incremental stimulation of the human tibialis anterior

BackgroundLocal oxygen supply/uptake mismatch (O2M) of active muscles may be influenced by the effectiveness of microvascular adaptations to metabolic demand. The aim of this work was to provide a novel, objective method to measure O2M through incremental stimulation.MethodsThe tibialis anterior of 20 subjects was electrically stimulated at the main motor point. The stimulation protocol involved five single twitches at maximal stimulus amplitude (Vmax = full motor unit recruitment) and five 90-s steps with increasing amplitude and frequency of the intermittent stimulation. Changes in force, oxygenated Hb (O2Hb) and deoxygenated Hb (HHb) were recorded. Contraction time (CT) of single twitches, fatigue index (FI) and O2M were calculated.ResultsF-statistics identified two groups of muscles, one with FI < 0.69 (group F, more fatiguable) and one with FI > 0.69 (group R, less fatiguable). Group R showed significantly lower CT, higher basal O2Hb, lower ΔHHb and lower O2M with respect to group F.ConclusionOn the basis of the relationship between O2M and FI, the proposed method distinguished two different functional capacities of human TA muscles. This tool could be applied to estimate the kinetics of aerobic adaptation to increasing metabolic demand in muscles affected by myopathies or subjected to rehabilitation or training programmes.

Exoskeleton for Gait Training in Spinal Cord Injured People: Clinical Analysis and Ethical Dilemmas

According to recent epidemiological surveys 2.5 millions of people affected by a Spinal Cord Injury (SCI) are experiencing a variable degree of disability.

Hand Passive Mobilization Performed with Robotic Assistance: Acute Effects on Upper Limb Perfusion and Spasticity in Stroke Survivors

This single arm pre-post study aimed at evaluating the acute effects induced by a single session of robot-assisted passive hand mobilization on local perfusion and upper limb (UL) function in poststroke hemiparetic participants. Twenty-three patients with subacute or chronic stroke received 20 min passive mobilization of the paretic hand with robotic assistance. Near-infrared spectroscopy (NIRS) was used to detect changes in forearm tissue perfusion. Muscle tone of the paretic UL was assessed by the Modified Ashworth Scale (MAS). Symptoms concerning UL heaviness, joint stiffness, and pain were evaluated as secondary outcomes by self-reporting. Significant (p = 0.014) improvements were found in forearm perfusion when all fingers were mobilized simultaneously. After the intervention, MAS scores decreased globally, being the changes statistically significant for the wrist (from 1.6 ± 1.0 to 1.1 ± 1.0; p = 0.001) and fingers (from 1.2 ± 1.1 to 0.7 ± 0.9; p = 0.004). Subjects reported decreased UL heaviness and stiffness after treatment, especially for the hand, as well as diminished pain when present. This study supports novel evidence that hand robotic assistance promotes local UL circulation changes, may help in the management of spasticity, and acutely alleviates reported symptoms of heaviness, stiffness, and pain in subjects with poststroke hemiparesis. This opens new scenarios for the implications in everyday clinical practice. Clinical Trial Registration Number is NCT03243123.

Dynamic Analysis of Handcycling: Mathematical Modelling and Experimental Tests

The handbike is an upper body-powered vehicle used for sports and rehabilitation purposes. The advantages include improving patients physical activities and fitness level, as well as promoting an active lifestyle after rehabilitation duration. In this research the torques in shoulder and elbow joints have been determined during handbike motion from dynamic output and kinematics information. Therefore, a 2D model was presented. Data have been collected based on the output of experimental results obtained by sensors inserted on the handles of a cycle ergometer and by marker coordinates acquired by a vision system.