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Acute effects of Flexi-bar vs. Sham-bar exercise on muscle electromyography activity and performance.

Abstract：

:This study was conducted to investigate whether the low-frequency (5-Hz) oscillatory vibration-like stimulus, purported to be delivered by exercising with Flexi-bar, acutely affects muscle activation and maximal voluntary contraction (MVC) force. Nine healthy men participated in 2 trials, separated by at least 1 week, during which 4 x 30-second sets of exercise were performed with either the Flexi bar or a Sham bar. Maximal voluntary contraction force for elbow flexion, elbow extension, and knee extension were measured before and after the exercise. Root-mean-square amplitude and median frequency of electromyography (EMG) signal were calculated for the first and last 10 seconds of each exercise set and during the MVCs from biceps brachii (BB), triceps brachii (TB), rectus femoris (RF), and vastus lateralis (VL) for each trial. Electromyography amplitude was significantly higher for all studied muscles during Flexi-bar than Sham-bar exercise (32-203%, p < 0.05). Median frequency of EMG power spectrum was significantly lower in arm (TB: -40 +/- 13%, p < 0.0001; BB: -32 +/- 25%, p = 0.015) but not in leg (RF: -12 +/- 18%; VL: +6 +/- 32%; p > 0.05) muscles during Flexi-bar compared with Sham-bar exercise. Knee extension MVC force significantly decreased after Flexi-bar exercise (-3 +/- 7%, p = 0.048) in parallel with reduced RF EMG amplitude (-8 +/- 5%, p = 0.04), but there were no acute residual effects on elbow flexion/extension MVC or arm and VL EMG muscle activity. Using Flexi bar during exercise provoked acute alterations in arm- and leg-muscle EMG parameters and maximum force-generating capacity, indicating greater fatigue development than when exercising with the Sham bar. The results of this study indicate that Flexi bar may therefore be used to impose a stronger training stimulus on the muscle during submaximal exercise.

journal_name

J Strength Cond Res

journal_title

Journal of strength and conditioning research

authors

Mileva KN,Kadr M,Amin N,Bowtell JL

doi

10.1519/JSC.0b013e3181c7c2d8

subject

Has Abstract

pub_date

2010-03-01 00:00:00

pages

737-48

issue

eissn

1064-8011

issn

1533-4287

journal_volume

pub_type

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Acute effects of Flexi-bar vs. Sham-bar exercise on muscle electromyography activity and performance.