Side-alternating vibration training for balance and ankle muscle strength in untrained women

Context: Side-alternating vibration (SAV) may help reduce the risk of falling by improving body balance control. Such training has been promoted as a strength-training intervention because it can increase muscle activation through an augmented excitatory input from the muscle spindles. Objective: To determine the effect of SAV training on static balance during 3 postural tasks of increasing difficulty and lower limb strength. Design: Randomized controlled clinical trial. Setting: Laboratory. Patients or Other Participants: A total of 21 healthy women were divided into training (n = 11; age = 43.35 6 4.12 years, height = 169 ± 6.60 cm, mass = 68.33 ± 11.90 kg) and control (n = 10; age = 42.31 ± 3.73 years, height = 167 ± 4.32 cm, mass = 66.29 ± 10.74 kg) groups. Intervention(s): The training group completed a 9-week program during which participants performed 3 sessions per week of ten 15-second isometric contractions with a 30-second active rest of 3 exercises (half-squat, wide-stance squat, 1- legged half-squat) on an SAV plate (acceleration=0.91-16.3g). The control group did not participate in any form of exercise over the 9-week period. Main Outcome Measure(s): We evaluated isokinetic and isometric strength of the knee extensors and flexors and ankle plantar flexors, dorsiflexors, and evertors. Static balance was assessed using 3 tasks of increasing difficulty (quiet bipedal stance, tandem stance, 1-legged stance). The electromyographic activity of the vastus lateralis, semitendinosus, medial gastrocnemius, tibialis anterior, and peroneus longus was recorded during postural task performance, baseline and pretraining, immediately posttraining, and 15 days posttraining. Results: After training in the training group, ankle muscle strength improved (P = .03), whereas knee muscle strength remained unaltered (P = .13). Improved ankle-evertor strength was observed at all angular velocities (P =.001). Postural sway decreased in both directions but was greater in the mediolateral (P < .001) than anteroposterior (P = .02) direction. The electromyographic activity of the peroneus longus increased during the sharpened tandem (P=.001) and 1-legged tasks (P= .007). No changes were seen in the control group for any measures. Conclusions: The SAV training could enhance ankle muscle strength and reduce postural sway during static balance performance. The reduction in mediolateral sway could be associated with the greater use of ankle evertors due to their strength improvement. © by the National Athletic Trainers' Association, Inc

Factors related to the incidence of injuries' appearance to volleyball players

The purpose of this study was to investigate the external risk factors that contribute to sports injuries experienced by Volleyball players. 114 Greek Volleyball players (61 male and 53 female) who participate in the Volleyball Championship including the A1 and A2 national division and the local championships, age 22.77 (SD = 4.85) participated in this study. A questionnaire survey was used for data collection purposes and the interviews were conducted on a personal level. Of the 114 volley ball players (94.5 response rate), reported 363 injuries, during a total exposure time of 34200 h/year for 5 years, representing an overall incidence of 0.63 injuries per player. The majority of the injuries were located in the ankle region (51.3%), followed by the knee (18.2%) and the back (12.4%). Most injuries (58.1%) were classified as being of moderate severity. Most injuries occurred during training (52.3%), and the 69.1% of them during the competitive season. The present study indicates that the risk of suffering an injury in volleyball is relatevly high therefore more researches are needed to accomplish in order practitioners and clinics prevent injuries in training period and competitions. © 2006 IOS Press. All rights reserved

Acute Effects of Stretching on Flexibility, Power and Sport Specific Performance in Fencers

Elite athletes are eager to perform to the best of their ability, regardless of different warm-up stretching techniques used before training or competition which actually help or hinder specific performance variables. The aim of this study was to investigate the acute effects of static or ballistic stretching on flexibility and leg power characteristics of fencing performance in fencers of both genders. Ten male and ten female international level fencers participated in this study. Each subject performed static or ballistic stretching (3 sets of 20 sec) on three muscles of the lower limbs on separate days. Flexibility, squat jump, countermovement jump, drop jump, time and power of lunge and shuttle run test were measured before and after different stretching interventions. Neither static nor ballistic stretching exercises affected flexibility, jumping ability and leg functional fencing performance tests. Moreover, stretching conditions did not affect differently. The results of this study suggest that static or ballistic stretching in the later stages of a general warm-up normally used before training or competition does not hinder specific performance in fencing. Consequently, fencers can continue performing any type of stretching before training or competition at their preference. © 2010, Versita. All rights reserved

Vibration effects on static balance and strength

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: 15-25Hz, amplitude: 2-12.8cm), 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. © 2010 Georg Thieme Verlag KG Stuttgart · New York