Search PubMed⌕ Search

Biomedical subjects

C Frigo

Publications and source records attributed to C Frigo.

29 records · Page 2Linked to original sources
PubMed1989

Muscular effort and musculo-skeletal disorders in piano students: electromyographic, clinical and preventive aspects.

An investigation was made on the relationship between music practice and musculo-skeletal disorders among piano students, with the main aim of developing health education programmes that would improve the performance and health of the students. The investigation covered three areas: (a) Analysis of study organization and main musculo-skeletal complaints achieved by a questionnaire distributed to all piano students at the Milan Conservatory. (b) Vocational electromyographic analysis of the effort exerted by the various muscle groups of the trunk, of the shoulder and shoulder blade girdle, and of the arm during performance of a standard set of piano exercises, an unseen passage and a passage of maximum difficulty. This analysis was made on a sample of six subjects. (c) A series of preventive measures was developed on the basis of a critical assessment of the results (38% of the students practised for excessively long periods without breaks; 62% had from 1 to 5 complaints, the most affected sites being the spine and the trapezius muscles). These consisted largely of a health education programme aimed at helping the students to suitably organize practice and rest periods and in instructing them in appropriate exercises for relaxation and stretching of overused muscle groups and strengthening the supporting muscle groups. Changes in lifestyle were also suggested.

Adolescent↗
PubMed1987

Forward and backward axial synergies in man.

Upper trunk and head forward and backward movements were analyzed in human subjects standing on a force platform. EMG of several flexor and extensor muscles was recorded together with the kinematics of the movement (EL.I.TE. system). It was found that upper trunk movements are accompanied by movements of hip and knees in the opposite direction, resulting in a slight displacement of the center of gravity projection on the ground. In fast movements, all the body segments were displaced at the same time, which suggests a feedforward control, whereas in slow movements, onset of displacement of the body segments was found to take place sequentially in a cranio-caudal direction. EMG analysis during fast movements revealed two different types of control, utilized in forward and backward movements. With forward bending movements the action of two sets of muscles could be recognized: the prime mover (R. Abd.), the activation of which was not correlated with that of the other muscles and preceded the onset of movement with a fairly constant lead, and a group of postural muscles, the activation (VM, TA) and inhibition (Sol) of which were closely correlated. By contrast, with backward movements, the prime mover (Er.S.) and the postural leg muscles (Hamstrings, Sol) were activated simultaneously. In both cases, a feedforward type of control is evident. Performance of the fast forward movements was accompanied by an initial forward displacement of the knee. The function of this phenomenon is discussed in term of a destabilizing action favouring the forward bending of the body or a prestretching of the knee extensor muscles increasing the strength of their subsequent contraction.

Adult↗
PubMed1987

Excitability of the soleus H-reflex arc during walking and stepping in man.

In eight normal subjects, the excitability of the soleus (Sol) H-reflex was tested in parallel with Sol length changes, EMGs of leg and thigh muscles and ground contact phases, during three different pacing movements: bipedal treadmill walking, single limb treadmill walking, and single-limb stepping on one spot. A computerized procedure was used which compensated for changes in stimulus effectiveness that occurred during free motion. In the three paradigms examined, significant excitability modulations were observed with respect to a control level determined in standing weight-bearing position. During bipedal treadmill walking, excitability was decreased in the early stance, maximally enhanced in the second half of the stance, and again decreased during the end-stance and the whole swing phase, with a minimum value around the toe off period. The main modulation pattern was retained during single-limb treadmill walking. During single-limb stepping on one spot, the stance-phase increase in excitability and the swing phase depression were still present. However, in the second half of the swing phase, reflex responsiveness returned to reference level, which was maintained during the subsequent contact period. Moreover, a decrease in reflex excitability was detected around the mid-stance. The time course of the described modulations was only partly correlated with the EMG and length changes of the Sol muscle. Furthermore, in the three movements tested, during the early stance phase, the excitability of the H-reflex arc did not correspond to the one expected on the basis of the available H-reflex studies performed under static conditions. It is suggested that, at least in certain stride phases (e.g. around the early contact period), an active regulation affects the transmission in the Sol myotatic arc during the pacing movements investigated.

Adult↗
PubMed1986

Speed-dependent variations of lower-limb joint angles during walking. A graphic computerized method showing individual patterns.

A method for obtaining a synthetic representation of the joint angle time-courses at different walking velocities is presented, based on a computerized procedure. Hip, knee and ankle joint angles are measured by electrogoniometric devices and checked on line for their reliability. One stride only for each walking speed is selected as representative of the adopted cadence. For each joint a tridimensional representation of angle time-course versus stride frequency or versus gait speed is performed so that speed-dependent variations can be analyzed. Ten normal (seven males and three females) and three prosthetized subjects have been tested by this method. In normal as well as in pathological subjects individual features could be easily detected and the method proved to be useful for a functional gait evaluation.

Adult↗
PubMed1985

Hindered muscle relaxation in spasticity: experimental evidence suggesting a possible pathophysiological mechanism.

In ten spastic patients and in an equal number of healthy controls, the relaxation phase occurring at the end of an isotonic voluntary contraction has been studied on soleus muscle using EMG and H-reflex methods. In the spastic group, the duration of motor unit-decruitment was consistently prolonged (from two to six times the control values). Moreover, the decrease in the excitability of the H-reflex arc, which normally accompanies the end of muscle contraction was delayed in time, reduced in amplitude or in some cases even absent. As a rule, patients in whom such release-associated inhibition (RAI) was lacking or severely reduced exhibited the longest motor unit-decruitment times, due to the interference of sustained clonic sequences. It is proposed that a lowered effectiveness of RAI might explain the clonic activity which frequently hinders voluntary muscle relaxation in spasticity.

Adult↗
PubMed1984

Evidence of phase-dependent nociceptive reflexes during locomotion in man.

In 10 healthy subjects freely walking along a straightline, the effects of painful sural nerve stimulation, applied in different phases of the step cycle, were investigated on two antagonistic muscles of the ipsilateral lower limb acting on the knee joint: vastus lateralis (VL) and biceps femoris caput breve (BF). A clear-cut modulation in the amplitude (area) of the net reflex responses was consistently observed in both the motor nuclei explored. The extensor muscle, VL, exhibited a long-latency (mean 122 ms) reflex response, which was maximally increased by stimuli applied toward the end of the swing and in the first half of the stance phase of the stride, whereas the response appeared to be gated during the transition from the foot-flat to forefoot-contact phase. A second facilitation period was brought about by stimuli delivered in the early swing. When the response occurred superimposed on the VL locomotor activity, suppression of the ongoing EMG preceded the reflex discharge. In the flexor, BF, the same stimulus elicited a short-latency (mean 57 ms) and a long-latency (mean 132 ms) reflex response. The former was maximal after stimulation around the toe-off phase and the latter was strikingly enhanced in the late swing, where it was preceded by suppression of the background locomotor EMG activity. Responses with intermediate features (latency 70 to 80 ms, duration 90 to 120 ms), probably resulting from the merging of the early and late components, might be evoked in addition, being greatest in the last swing and in the period preceding toe-off. The findings show that in man the reflex pattern evoked by a painful cutaneous stimulus during locomotion is determined by the phase of the step cycle during which the stimulus is delivered. A functional role in maintenance of postural balance during destabilizing withdrawal reactions is conceivable.

Adult↗
PubMed1978

A model of the mechanism controlling neuromuscular activation during ambulation based on feedback control hypothhesis.

As tested by many investigators, locomotor performance at steady state does not involve high conscious systems but takes place almost automatically. A great number of experiments on animals seem to demonstrate that the afferent proprioceptive signals play an important role in locomotion and that the higher nervous centers act in order to activate the lower control systems. On the basis of previous findings, we hypothesized that the descending signal from the higher nervous centers can lower the threshold of intervention of the proprioceptive signals on the alpha-motoneurons. The influences of the afferent signals on the various muscles enable them to realize the pattern of the basic muscular activity that we can record from walking subjects. A simulation of the model of human locomotion has been implemented on a digital computer and the theoretical results are compared with the experimental findings.

Afferent Pathways↗
PubMedDate not supplied

[Instrumental studies in laboratories dedicated to the examination of disk overload in health workers].

The main factors to be considered when applying movement analysis techniques to complex situations are analysed. In particular, when the mechanical interactions of the operator with an object to be handled are not easily measurable, as in the case of lifting a patient in a nursery, an approach in which the ground reaction forces are measured through a force platform is more convenient. In these situations the posture and the movement of the subject, that are also difficult to track, do not need to be analysed. The only information needed is the position and orientation of the intervertebral disk and some estimation of the anthropometric parameters of the part of the body which is below the vertebral level of interest. This can be achieved by a relatively simple approach and a few reasonable assumptions. In addition, the method can enable us to analyse forces and moments in 3-D. The results presented refer to several kinds of operations that are usually performed with hospital patients. They include bed to wheelchair transfer, assistance with standing up from a chair, repositioning the patient in bed. It is shown that the compression loads (1810 N to 5110 N) are comparable to those already reported in the literature. In addition, the transversal components (anterior (260 N-707 N) and lateral (5 N-200 N) shear) are of considerable interest. It is also shown how the use of appropriate ergonomical devices to help patient lifting and handling can considerably reduce the loads on the spine: in fact the compression loads are between 991 N and 1644 N.

Biomechanical Phenomena↗