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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 rad s-2), 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. [ABSTRACT FROM AUTHOR]

People with Parkinson's disease (PD) often have a posture characterized by lateral trunk flexion poorly responsive to antiparkinsonian drugs. To examine the effects of a rehabilitation programme (daily individual 90-minute-sessions, 5-days-a-week for 4-consecutive weeks) on lateral trunk flexion and mobility, 22 PD patients with mild to severe lateral trunk flexion, and 22 PD patients without trunk flexion were studied. Patients were evaluated using the Unified Parkinson's Disease Rating Scale motor subscale (UPDRS-III) score, and the kinematic behavior of the trunk was recorded by means of an optoelectronic system to determine: a) trunk flexion, inclination and rotation values in the erect standing posture; b) ranges of trunk flexion and inclination during trunk movements. After the treatment, significant decreases in trunk flexion [24°(4) vs. 14°(3), P < 0.001] and inclination in the static condition [23°(5) vs. 12°(4), P < 0.001)] were observed, both of which were maintained at the 6-month follow up. During the trunk flexion task, a significantly increased range of trunk flexion [64°(15) vs. 83°(15), P < 0.001] was observed; similarly, during the lateral bending task, the range of trunk inclination was found to be significantly increased, both toward the side of the trunk deviation [29°(8) vs. 42°(13), P < 0.01] and toward the contralateral side [14°(6) vs 29°(11), P < 0.01]. No further significant changes were observed at the 6-month follow-up. Trunk flexion and inclination values in the upright standing posture correlated slightly with the UPDRS-III score. Our findings show that significant improvements in axial posture and trunk mobility can be obtained through the 4-week rehabilitation programme described, with a parallel improvement in clinical status. © 2010 Movement Disorder Society [ABSTRACT FROM AUTHOR]

In the present study we investigated the probability, latency and duration of the inhibitory component of the withdrawal reflex elicited by painful electrical stimulation of the index finger in humans. The stimulus consisted of a train of high-intensity pulses. The investigation was carried out in several upper limb muscles during isometric contractions of different strengths and during a motor sequence consisting of reaching, picking up and transporting an object. We used a new algorithm to detect and characterize the inhibitory reflex. The reflex was found in all muscles except the brachioradialis at all the isometric contraction strengths, and showed a distal-to-proximal gradient of latency and duration. Conversely, during movement the reflex probability was high (> 80%) in the anterior deltoid and triceps muscles during reaching, in the extensor carpi radialis muscle during transporting of the object, and in the first interosseous muscle during both picking up and transporting of the object. This modulation of inhibitory reflex transmission in the upper limb muscles suggests that the motor response is organized in such a way as to inhibit the overall ongoing motor task by interrupting motion during reaching and by releasing the object during transporting. This pattern of modulation appears to differ markedly from that previously reported for the excitatory component of the withdrawal reflex. Study of the nociceptive inhibitory reflexes during movement offers new and more profound insights into the functional anatomical organization of the spinal interneuronal network mediating sensory–motor integration. [ABSTRACT FROM AUTHOR]