Biomedical subjects

Luigi Fattorini

Publications and source records attributed to Luigi Fattorini.

3 recordsLinked to original sources

PubMed2006

Motor performance changes induced by muscle vibration.

The possibility that mechanical stimulation of selected muscles can act directly on the nervous system inducing persistent changes of motor performances was explored. On the basis of literature, stimulating parameters were chosen to stimulate the central nervous system and to avoid muscle fibre injuries. A sinusoidal mechanical vibration was applied, for three consecutive days, on the quadriceps muscle in seven subjects that performed a muscular contraction (VC). The same stimulation paradigm was applied on seven subjects in relaxed muscle condition (VR) and seven subjects were not treated at all (NV). Two sessions (PRE and POST) of isometric and isotonic tests were performed separated for 21 days, in all studied groups 7 days before and 15 days after stimulation, whilst an isokinetic test was performed on VC only. In the isometric test, the time of force development showed a significant decrease only in VC (POST vs PRE mean 27.8%, P < 0.05). In the isotonic test, the subjects' had to perform a fatiguing leg extension against a load. In this condition, the fatigue resistance increased greatly in VC (mean 40.3%, P < 0.001), increased slightly in VR and there was no difference in NV. In Isokinetic test, at several angular velocities, significantly less time was required to reach the force peak (mean 20.2% P < 0.05). The findings could be ascribed to plastic changes in proprioceptive processing, leading to an improvement in knee joint control. Such action delineates a new tool in sports training and in motor rehabilitation.

Adaptation, Physiological↗

PubMed2004

Differences in the force/endurance relationship between young and older men.

The aim of the present study was to ascertain if in six young (23-35 years) and in six older (70-72 years) healthy men matched for comparable absolute and specific maximal force of the dominant elbow flexors, differences in isometric endurance, myoelectrical fatigability, and shortening velocity are still recognizable. To assess the specific force, the muscle cross sectional area (CSA) was determined from magnetic resonance imaging (MRI) scans. The performance of the elbow flexors was studied by assessing the isometric endurance times (ET) at different percentages of maximal isometric contraction (MVC), the average muscle fibre conduction velocity of action potentials (CV), and the median frequency (MDF) of the surface electromyogram (sEMG) of the biceps brachii. Finally, the torque-velocity curve was assessed by means of maximal isokinetic contractions at six fixed angular velocities. All data were expressed as the mean (SD). The results showed that: (1) the ET was longer in the older subjects at the highest levels of isometric contraction, independently from the absolute force; (2) the modifications of muscle fibre CV during isometric effort progressed less rapidly in the older than the younger groups, as did those of MDF; and (3) at the same angular velocity, the older subjects exerted less absolute force than the younger subjects. These results suggest an impairment of the neuromuscular system of older men, which is less powerful and less fatigable than that of young men.

Adult↗

PubMed2002

Nonlinear surface EMG analysis to detect changes of motor unit conduction velocity and synchronization.

Amplitude and frequency content of the surface electromyographic (EMG) signal reflect central and peripheral modifications of the neuromuscular system. Classic surface EMG spectral variables applied to assess muscle functions are the centroid and median power spectral frequencies. More recently, nonlinear tools have been introduced to analyze the surface EMG; among them, the recurrence quantification analysis (RQA) was shown to be particularly promising for the detection of muscle status changes. The purpose of this work was to analyze the effect of motor unit short-term synchronization and conduction velocity (CV) on EMG spectral variables and two variables extracted by RQA, the percentage of recurrence (%Rec) and determinism (%Det). The study was performed on the basis of a simulation model, which allowed changing the degree of synchronization and mean CV of a number of motor units, and of an experimental investigation of the surface EMG signal properties detected during high-force-level isometric fatiguing contractions of the biceps brachii muscle. Simulations and experimental results were largely in agreement and show that 1) spectral variables, %Rec, and %Det are influenced by CV and degree of synchronization; 2) spectral variables are highly correlated with %Det (R = -0.95 in the simulations and -0.78 and -0.75 for the initial values and normalized slopes, respectively, in the experimental signals), and thus the information they provide on muscle properties is basically the same; and 3) variations of %Det and %Rec in response to changes in muscle properties are significantly larger than the variations of spectral variables. This study validates RQA as a means for fatigue assessment with potential advantages (such as the higher sensitivity to changes of muscle status) with respect to the classic spectral analysis.

Adult↗