High bar swing performance in novice adults: effects of practice and talent.

An individual's a priori talent can affect movement performance during learning. Also, task requirements and motor-perceptual factors are critical to the learning process. This study describes changes in high bar swing performance after a 2-month practice period. Twenty-five novice participants were divided by a priori talent level (spontaneous-talented [ST] and nonspontaneous-talented [NST]) and compared to experienced gymnasts. Additionally, we assessed their perception of their performance level before and after practice. We defined three events independently for hip (H) and shoulder (S) angle joints and for the lag between consecutive events (phases [P]): the smallest angle during downswing (P1H, P1S), the largest angle after P1 (P2H, P2S), and the smaller angle during upswing (P3H, P3S). Movement performance variables were the maximum elevation on the downswing (Pi) and the upswing (Pf), and the total path between both (swing amplitude). Data were collected during pre- and postpractice sessions by two video cameras. At the end of both sessions, participants drew a sketch to represent their perception of their performance level relative to the Pi, Pf and the hip events. Results showed a similar practice effect in the swing amplitude in both novice groups. However the ST group 's performance and perception variables on the downswing improved more than the NST group due to practice. This study suggests that (a) downswing improvements were easier than in the upswing, possibly due to familiarity of the visual reference in combination with proprioceptive feedback; and (b) being ST may involve a better orfaster gain in perception of self-action compared to NST.

A vibratory bar for upper body: feasibility and acute effects on EMGrms activity.

The purpose of this study was to determine the feasibility of a purpose-designed vibratory bar (VB) as a potential vibration training device and thereafter to assess its effects on upper-body muscles' electromyographic (EMG) activity during vibration. During session 1, 16 physically active males held the VB during the bench press exercise in an isometric extended position (EP) in the following vibration conditions selected in the inverter (i): no vibration (0), 20, 30, 40, and 50 Hzi. Maximal acceleration (Accmax), frequency (Freq), and peak-to-peak amplitude (Ampp-p) obtained at the center (C) and at the end (E) of the VB were assessed using an accelerometer. During session 2, EMGrms of the triceps, deltoid, and pectoralis major were recorded in EP and isometric flexion position (FP) at 0, 25, and 45 Hzi. The Accmax, Freq, and Ampp-p values ranged from 37.4 to 96.4 mxs, 18.5 to 30.8 Hz, and 4.6 to 6.1 mm, respectively. The accelerometer's position had a significant effect on the Accmax and Ampp-p. All Freq obtained at C and E were different (p < 0.001) to the Freqi. An increase (p < 0.05) in EMGrms was observed in both vibration conditions compared with 0 Hzi, except during 25Hzi for deltoid and pectoralis muscle in FP. Although no significant differences were found in any of the muscles between 45 Hzi and 25Hzi, the highest EMGrms was elicited at 45Hzi. Although the registered VBs' parameters seem appropriate for vibration training, the frequency in the FP should be higher than 25 Hzi to induce significant increases in EMGrms in deltoid and pectoralis muscles. The use of a vibratory bar may be a suitable system to simultaneously stimulate upper-body muscles.