COMPARISON OF TWO VARIANTS OF A KATA TECHNIQUE (UNSU): THE NEUROMECHANICAL POINT OF VIEW

The objective of this work was to characterize from a neuromechanical point of view a jump performed within the sequence of Kata Unsu in International top level karateka. A modified jumping technique was proposed to improve the already acquired technique. The neuromechanical evaluation, paralleled by a refereeing judgment, was then used to compare modified and classic technique to test if the modification could lead to a better performance capacity, e.g. a higher score during an official competition. To this purpose, four high ranked karateka were recruited and instructed to perform the two jumps. Surface electromyographic signals were recorded in a bipolar mode from the vastus lateralis, rectus femoris, biceps femoris, gluteus maximus, and gastrocnemious muscles of both lower limbs. Mechanical data were collected by means of a stereophotogrammetric system and force platforms. Performance was associated to parameters characterizing the initial conditions of the aerial phase and to the CoM maximal height. The most critical elements having a negative influence on the arbitral evaluation were associated to quantitative error indicators. 3D reconstruction of the movement and videos were used to obtain the referee scores. The Unsu jump was divided into five phases (preparation, take off, ascending flight, descending flight, and landing) and the critical elements were highlighted. When comparing the techniques, no difference was found in the pattern of sEMG activation of the throwing leg muscles, while the push leg showed an earlier activation of RF and GA muscles at the beginning of the modified technique. The only significant improvement associated with the modified technique was evidenced at the beginning of the aerial phase, while there was no significant improvement of the referee score. Nevertheless, the proposed neuromechanical analysis, finalized to correlate technique features with the core performance indicators, is new in the field and is a promising tool to perform further analyse

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

Exercise at lunchtime: effect on glycemic control and oxidative stress in middle-aged men with type 2 diabetes

PURPOSE: Postprandial hyperglycemia and glycemic oscillations have been associated with increased oxidative stress. We sought to investigate the effect of two walking exercise protocols performed during lunchtime on glycemic control and oxidative stress in type 2 diabetic (T2D) patients. METHODS: Nine T2D patients participated in three randomized crossover trials; a control trial (Con), with participants having a standard lunch followed by their normal daily activities and two exercise trials (ContEx and Splitex). In ContEx, subjects performed 40 min of brisk walking 40 min after lunch, whereas in SplitEx the walking exercise was divided in two 20-min isoenergetic bouts, before and 40 min after meal. 24-h glycemic control was monitored by continuous glucose monitoring. 24-h urinary levels of 8-iso PGF2ɑ were measured as a marker of oxidative stress. RESULTS: SplitEx resulted in less time spent in moderate hyperglycemia after lunch vs ContEx (42.4 ± 38.7% vs 68.2 ± 32.7%, P = 0.04). ContEx reduced hyperglycemic time after breakfast consumed the morning after the exercise session (58.3 ± 29.6 Con vs 40.2 ± 33.4% ContEx, P = 0.02). Compared with Con, 24-h urinary isoprostanes were decreased both in ContEx (-68%, P = 0.02) and SplitEx (-63%, P = 0.04). CONCLUSIONS: Splitting an exercise session into two bouts, pre- and post-lunch, affects mainly the glycemic response to lunch, while a single-continuous isoenergetic session exerts its effect later in the 24-h period. Both exercise modalities effectively attenuate systemic oxidative stress with similar overall benefits

Exercise at lunchtime: effect on glycemic control and oxidative stress in middle-aged men with type 2 diabetes

PURPOSE: Postprandial hyperglycemia and glycemic oscillations have been associated with increased oxidative stress. We sought to investigate the effect of two walking exercise protocols performed during lunchtime on glycemic control and oxidative stress in type 2 diabetic (T2D) patients. METHODS: Nine T2D patients participated in three randomized crossover trials; a control trial (Con), with participants having a standard lunch followed by their normal daily activities and two exercise trials (ContEx and Splitex). In ContEx, subjects performed 40 min of brisk walking 40 min after lunch, whereas in SplitEx the walking exercise was divided in two 20-min isoenergetic bouts, before and 40 min after meal. 24-h glycemic control was monitored by continuous glucose monitoring. 24-h urinary levels of 8-iso PGF2ɑ were measured as a marker of oxidative stress. RESULTS: SplitEx resulted in less time spent in moderate hyperglycemia after lunch vs ContEx (42.4 ± 38.7% vs 68.2 ± 32.7%, P = 0.04). ContEx reduced hyperglycemic time after breakfast consumed the morning after the exercise session (58.3 ± 29.6 Con vs 40.2 ± 33.4% ContEx, P = 0.02). Compared with Con, 24-h urinary isoprostanes were decreased both in ContEx (-68%, P = 0.02) and SplitEx (-63%, P = 0.04). CONCLUSIONS: Splitting an exercise session into two bouts, pre- and post-lunch, affects mainly the glycemic response to lunch, while a single-continuous isoenergetic session exerts its effect later in the 24-h period. Both exercise modalities effectively attenuate systemic oxidative stress with similar overall benefits

Effects of L-carnitine, L-acetylcarnitine and gangliosides on the regeneration of the transected sciatic nerve in rats

Three pharmacological agents, L-carnitine, L-acetylcarnitine and gangliosides, were tested for their ability to enhance the regeneration of the rat sciatic nerve following transection and microsurgical repair. The drugs were administered intraperitoneally at the dose of 50 mg/kg/d for 28 and 56 d postoperatively. At the end of treatment, the motor function recovery of the peroneal component of the sciatic nerve was assessed and the regenerated nerves were analysed morphometrically on histological semi-thin sections. Also, the reinnervated extensor digitorum longus (EDL) muscles were studied histochemically using the adenosine-triphosphatase (ATP-ase) technique 56 d after surgery. Motor function assessment at 56 d after nerve repair revealed that L-acetylcarnitine-treated animals recovered a clinical grade significantly higher (p less than 0.05) than the control animals. Twenty-eight days after nerve repair, the number of myelinated fibres was significantly higher (p less than 0.05) in L-acetylcarnitine and ganglioside-treated animals than in control animals. However, 56 d after nerve repair the number of regenerated fibres in all the drug-treated groups was not significantly different from that of the control group. The EDL muscles of the drug-treated animals did not show significant differences from those of control animals with respect to fibre composition and fibre diameter although the L-acetylcarnitine-treated animals exhibited a significantly lower (p less than 0.05) degree of muscle atrophy than did the control animals. The results of the present work seem to indicate that L-acetylcarnitine and to a lesser extent gangliosides exert some favourable effect on the regeneration of the transected sciatic nerve in rats.(ABSTRACT TRUNCATED AT 250 WORDS