Bilateral index, power, force, and velocity during bench press with different loads in male handball players.

Bilateral index for upper limbs was determined for maximal force, speed and power in 18 male handball players. Variables were individually assessed with a functional electromechanical dynamometer during unilateral and bilateral bench press push-off for 40%, 60%, and 75% of the maximal isometric force. Limb dominance (symmetry indices) and load effects in the bilateral index were analysed. Bilateral index showed a bilateral deficit for power (range = -8.50 to -41.48) and velocity (range = -11.15 to -38.41), that increases with the load (p < 0.05). For maximum force, a bilateral facilitation (range = 2.26-5.57), which did not vary significantly as a function of load, was observed. Symmetry indices showed no association with the bilateral index (40% load: r = 0.45, 60% load: r = 0.05, 75% load: r = 0.39). These results contribute to understanding the phenomenon; however, individual-to-individual observation reflects that caution should be kept when assessing an individual athlete. In conclusion, bilateral deficit or facilitation for bench press depends on the variable considered, whereas its magnitude depends on the load. Moreover, limb dominance does not affect it. This finding must be regarded as a general trend, but a different situation may occur during the assessment of a particular athlete.

Emotional face expressions recognition in childhood: developmental markers, age and sex effect.

Recognizing emotional face expressions in others is a valuable non-verbal communication and particularly relevant throughout childhood given that children's language skills are not yet fully developed, but the first interactions with peers have just started. This study aims to investigate developmental markers of emotional facial expression in children and the effect of age and sex on it. A total of 90 children split into three age groups: 6-7 years old (n = 30); 8-9 years old (n = 30); 10-11 years old (n = 30) took part in the study. Participants were exposed to 38 photos in two exposure times (500 ms and 1000 ms) of children expressing happiness, sadness, anger, disgust, fear and surprise on three intensities, plus images of neutral faces. Happiness was the easiest expression to be recognized, followed by disgust and surprise. As expected, 10-11-year-old group showed the highest accuracy means, whereas 6-7-year-old group had the lowest means of accuracy. Data support the non-existence of female advantage.

Two Pathways for the Activity-Dependent Growth and Differentiation of Synaptic Boutons in Drosophila.

Synapse formation can be promoted by intense activity. At the Drosophila larval neuromuscular junction (NMJ), new synaptic boutons can grow acutely in response to patterned stimulation. We combined confocal imaging with electron microscopy and tomography to investigate the initial stages of growth and differentiation of new presynaptic boutons at the Drosophila NMJ. We found that the new boutons can form rapidly in intact larva in response to intense crawling activity, and we observed two different patterns of bouton formation and maturation. The first pathway involves the growth of filopodia followed by a formation of boutons that are initially devoid of synaptic vesicles (SVs) but filled with filamentous matrix. The second pathway involves rapid budding of synaptic boutons packed with SVs, and these more mature boutons are sometimes capable of exocytosis/endocytosis. We demonstrated that intense activity predominantly promotes the second pathway, i.e., budding of more mature boutons filled with SVs. We also showed that this pathway depends on synapsin (Syn), a neuronal protein which reversibly associates with SVs and mediates their clustering via a protein kinase A (PKA)-dependent mechanism. Finally, we took advantage of the temperature-sensitive mutant sei to demonstrate that seizure activity can promote very rapid budding of new boutons filled with SVs, and this process occurs at scale of minutes. Altogether, these results demonstrate that intense activity acutely and selectively promotes rapid budding of new relatively mature presynaptic boutons filled with SVs, and that this process is regulated via a PKA/Syn-dependent pathway.