Fabio Massimo Botti

Improvement of Stance Control and Muscle Performance Induced by Focal Muscle Vibration in Young-Elderly Women: A Randomized Controlled Trial

UNLABELLED Filippi GM, Brunetti O, Botti FM, Panichi R, Roscini M, Camerota F, Cesari M, Pettorossi VE. Improvement of stance control and muscle performance induced by focal muscle vibration in young-elderly women: a randomized controlled trial. OBJECTIVE To determine the effect of a particular protocol of mechanical vibration, applied focally and repeatedly (repeated muscle vibration [rMV]) on the quadriceps muscles, on stance and lower-extremity muscle power of young-elderly women. DESIGN Double-blind randomized controlled trial; 3-month follow-up after intervention. SETTING Human Physiology Laboratories, University of Perugia, Italy. PARTICIPANTS Sedentary women volunteers (N=60), randomized in 3 groups (mean age +/- SD, 65.3+/-4.2y; range, 60-72). INTERVENTION rMV (100Hz, 300-500microm, in three 10-minute sessions a day for 3 consecutive days) was applied to voluntary contracted quadriceps (vibrated and contracted group) and relaxed quadriceps (vibrated and relaxed group). A third group received placebo stimulation (nonvibrated group). MAIN OUTCOME MEASURES Area of sway of the center of pressure, vertical jump height, and leg power. RESULTS Twenty-four hours after the end of the complete series of applications, the area of sway of the center of pressure decreased significantly by approximately 20%, vertical jump increased by approximately 55%, and leg power increased by approximately 35%. These effects were maintained for at least 90 days after treatment. CONCLUSIONS rMV is a short-lasting and noninvasive protocol that can significantly and persistently improve muscle performance in sedentary young-elderly women.

Prolonged asymmetric vestibular stimulation induces opposite, long‐term effects on self‐motion perception and ocular responses

•  The semicircular canals of the labyrinths are a source of information for self‐motion perception and reflex eye movements. •  Prolonged vestibular asymmetric stimulation of standing humans about the earth‐vertical axis, made of fast body rotation to one side and slow rotation to the other side, induced different adaptive mechanisms in the perception of body motion and in the vestibulo‐ocular reflex (VOR). •  Motion perception became progressively more asymmetric, increasing gradually in response to the fast body rotation and decreasing in response to the slow rotation. VOR became gradually more symmetric, decreasing for fast body movement and increasing for slow movement. •  These oppositely directed adaptive effects in motion perception and VOR persisted for at least 30 min. •  Long‐lasting asymmetric stimulation discloses independent brain mechanisms for perception of body motion and eye movement control. •  These adaptive mechanisms may enhance awareness toward the side where the body is moving faster, while improving eye stabilizing properties of the VOR.

Kv1.1 knock-in ataxic mice exhibit spontaneous myokymic activity exacerbated by fatigue, ischemia and low temperature.

Episodic ataxia type 1 (EA1) is an autosomal dominant neurological disorder characterized by myokymia and attacks of ataxic gait often precipitated by stress. Several genetic mutations have been identified in the Shaker-like K+ channel Kv1.1 (KCNA1) of EA1 individuals, including V408A, which result in remarkable channel dysfunction. By inserting the heterozygous V408A, mutation in one Kv1.1 allele, a mouse model of EA1 has been generated (Kv1.1V408A/+). Here, we investigated the neuromuscular transmission of Kv1.1V408A/+ ataxic mice and their susceptibility to physiologically relevant stressors. By using in vivo preparations of lateral gastrocnemius (LG) nerve–muscle from Kv1.1+/+ and Kv1.1V408A/+ mice, we show that the mutant animals exhibit spontaneous myokymic discharges consisting of repeated singlets, duplets or multiplets, despite motor nerve axotomy. Two-photon laser scanning microscopy from the motor nerve, ex vivo, revealed spontaneous Ca2 + signals that occurred abnormally only in preparations dissected from Kv1.1V408A/+ mice. Spontaneous bursting activity, as well as that evoked by sciatic nerve stimulation, was exacerbated by muscle fatigue, ischemia and low temperatures. These stressors also increased the amplitude of compound muscle action potential. Such abnormal neuromuscular transmission did not alter fiber type composition, neuromuscular junction and vascularization of LG muscle, analyzed by light and electron microscopy. Taken together these findings provide direct evidence that identifies the motor nerve as an important generator of myokymic activity, that dysfunction of Kv1.1 channels alters Ca2 + homeostasis in motor axons, and also strongly suggest that muscle fatigue contributes more than PNS fatigue to exacerbate the myokymia/neuromyotonia phenotype. More broadly, this study points out that juxtaparanodal K+ channels composed of Kv1.1 subunits exert an important role in dampening the excitability of motor nerve axons during fatigue or ischemic insult.

Subjective visual vertical before and after treatment of a BPPV episode

OBJECTIVE The study analyses the behavior of subjective visual vertical (SVV) in benign paroxysmal positional vertigo (BPPV) before and after treatment, and offers a clinical-pathogenic interpretation. METHODS We studied 30 consecutive patients with BPPV of the posterior semicircular canal treated with the Epley repositioning maneuver. SVV was determined at three different stages: at the time of diagnosis (1st test), after the repositioning maneuver (2nd test), and then 7 days after the resolution of the clinical picture (3rd test). The main study parameter was represented by the mean of 6 consecutive measurements (SVV(0)) for each patient. SVV was also examined in 20 healthy subjects, who represented the control group. The comparison between mean values and standard deviations showed a statistical significance of p<0.05. RESULTS During the first test, the degree of deviation of SVV was significantly higher in the patient group than in the control group. Tilting towards the affected side was observed in all cases. The 2nd test showed an inversion in the orientation of SVV in 16 patients, and as a result of the Epley maneuver there was a statistically significant variation in SVV(0) values in 20 patients with respect to the previous test (2nd test vs. 1st test). This involved 87% (23 patients) of those who then had a negative Dix-Hallpike test, and none of the ones in whom paroxysmal positional nystagmus persisted. Lastly, no differences emerged in the behavior of the patient group vs. the control group during the third test. CONCLUSIONS SVV is often altered during active BPPV. The degree of otolithic dysfunction is never high and, in all cases, it is brief in duration. Tilting towards the dysfunctional side is essentially a constant in untreated BPPV. This could be due to a substantial loss of otoconia, with a decrease in the density and specific weight of the macula, and thus hypofunction of the receptor. The observation of a significant variation in SVV after therapeutic maneuvers has a favorable predictive value, as it probably reflects the migration of otoliths to the utricle, where saturation mechanisms can often have irritative effects leading to the inversion of SVV.

Selective contribution of each hamstring muscle to anterior cruciate ligament protection and tibiofemoral joint stability in leg-extension exercise: a simulation study.

A biomechanical model was developed to simulate the selective effect of the co-contraction force provided by each hamstring muscle on the shear and compressive tibiofemoral joint reaction forces, during open kinetic-chain knee-extension exercises. This model accounts for instantaneous values of knee flexion angle

Self-motion perception and vestibulo-ocular reflex during whole body yaw rotation in standing subjects: The role of head position and neck proprioception

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Voluntary Enhanced Cocontraction of Hamstring Muscles During Open Kinetic Chain Leg Extension Exercise Its Potential Unloading Effect on the Anterior Cruciate Ligament

, angular velocity and acceleration, and for changes in magnitude, orientation, and application point of external resistance. The tibiofemoral shear force (TFSF) largely determines the tensile force on anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). Biceps femoris is the most effective hamstring muscle in decreasing the ACL-loading TFSF developed by quadriceps contractions for