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To examine torque variability in 2 antagonistic muscles 20 individuals performed maximal and submaximal (5, 10, 20, 50 and 75% of Maximal Voluntary Contraction, MVC) isometric wrist flexions and extensions (5 s) at 5 different angles (230, 210, 180, 150 and 130°). The EMG activity of Flexor Carpi Ulnaris (FCU) and Extensor Digitorum (ED) was recorded and quantified as the integral of EMG. Participants showed higher maximal isometric torque (32.43±11.17 vs. 17.41±3.84 Nm) and lower coefficient of variability during wrist flexion compared to extension. The normalized agonist EMG increased across higher levels of torque for both wrist muscles. Interestingly, the coactivation of ED during wrist flexion was greater compared to the coactivation of FCU during wrist extension at 50 and 75% of MVC, regardless of wrist angle (f.e.: at 180° and 75% of MVC the normalised EMG of ED as antagonist was 14.84±5.18% vs. 9.33±6.94 of the FCU). It is concluded that a stronger isometric wrist flexion is more steadily produced, with greater coactivation compared to a weaker wrist extension, independently from muscle length and torque level. Even if the relative contribution of antagonists to the resultant torque is to be considered, altered activation patterns responsible for differences in force fluctuations could be suggested., (Georg Thieme Verlag KG Stuttgart · New York.)

The purpose of this study was to investigate the effects of a vibration training protocol and a conventional strength training program consisting of similar exercises on knee extensors and flexors strength and postural sway in middle-aged women. 38 women were randomly assigned into a Vibration Group (n=12, static and dynamic exercises on a vibration plate, frequency: 15-25 Hz, amplitude: 2-12.8 cm), a Strength Group (n=16, same exercises without vibration) and a Control Group (n=10). Both experimental groups trained for 12 weeks (3 sessions/w). Static balance was assessed in 3 tasks of increasing difficulty: Normal Quiet Stance, Sharpened Tandem, and One-Legged Stance. Postural sway was evaluated using the Centre of Pressure variations in the Anterior/Posterior and Medio/Lateral direction. Eccentric and concentric strength of knee extensors and flexors was recorded using a Cybex dynamometer. After vibration training, postural sway significantly decreased in both directions for the vibration group in all tasks (p<0.05), whereas no significant differences were observed for the other groups. Isokinetic strength significantly (p<0.05) increased for both experimental groups at selected angular velocities. It was concluded that side-alternating vibration could have beneficial effects on static balance control for middle-aged women. Gains in isokinetic strength were quite similar for both experimental groups., (Georg Thieme Verlag KG Stuttgart . New York.)

The aim of this study was to investigate the influence of a 4-week electromyostimulation training program on the strength of the knee extensors and the vertical jump performance of 10 basketball players. Electromyostimulation sessions were carried out 3 times weekly; each session consisted of 48 contractions. Testing was carried out before and after the electromyostimulation training program (week 4) and once more after 4 weeks of normal basketball training (week 8). At week 4, isokinetic strength increased significantly (p < 0.05) at eccentric and high concentric velocities (between 180 and 360 x s(-1)); this was not the case for low concentric velocities (60 and 120 degrees x s(-1)). Electromyostimulation training increased also isometric strength at the two angles adjacent to the training angle (p < 0.01). Squat jump increased significantly by 14% at week 4 (p < 0.01), whereas counter movement-jump showed no change. At week 8, gains in isokinetic, isometric strength and squat-jump performance were maintained and the counter movement jump performance increased significantly by 17% (p<0.01). Electromyostimulation as part of a short strength-training program enhanced knee extensor strength and squat jump performance of basketball players.