Abstract: Although exercise speed is an acute variable to prescribe abdominalstrengthening programs, current literaturelacks studies analyzing the influence of speed on muscular activation in abdominal exercises. The aim of this work was to determine the influence of trunk curl-up speed on the amplitude of muscular activation and the way in which the trunk muscles were coactivated. Twenty recreationally trained volunteers (16 women and 4 men; age, 23.7 6 4.3 years; height, 166.2 6.3 cm; mass, 61.0 8.2 kg) participated in this study. Surface electromyographic data were collected from the rectus abdominis, external oblique, internal oblique, and erector spinae during 4 different curlup cadences [1 repetition per 4 seconds (C4), 1 repetition per 2 seconds (C2), 1 repetition per 1.5 seconds (C1.5), 1 repetition per 1 second (C1)], and during maximum speed curl-ups (Cmax). The electromyographic amplitude was averaged and normalized using maximum voluntary isometric contractions (MVICs). Statisticalanalyses were performed using repeated-analyses of variance. Normalized electromyographic mean amplitudes of trunk muscles increased with curl-up speed. Although the rectus abdominis (ranged from 23.3% of MVICs at C4to 49.6% of MVICs at Cmax) andinternal oblique (ranged from 19.2% ofMVICs at C4 to 48.5% of MVICs at Cmax)were the most active analyzedmuscles at each speed, contribution of the external oblique increased appreciably with velocity (ranged from 5.3% of MVICs at C4 to 33.3% of MVICs at Cmax). Increasing trunk curl-upspeed supposed greater trunk muscular coactivation, probably required for a faster performance and to ensure dynamic spine stability. On the basis of our findings, curl-up speed had an important effect on trunk muscular recruitment and must be taken into account when prescribing exercise programs for abdominal conditioning.

Abstract: The aim of this study was to analyze the intensity of contraction and the muscular coordination of one subject�s 14 trunk and shoulder muscles during the reception and throwing of a medicine ball (plyometric task), the standing cable chest press and the use of the Bodyblade® (flexible foil whose oscillation generates body vibrations and continuous unbalances). Muscular responses to controlled trunk loading and unloading were recorded, enabling a discussion about active spine stabilization. Our results indicate that trunk muscular activation is important to both stabilize the spine under sudden perturbations and to perform activities where the upper limbs handle and use objects. Coactivation of the trunk muscles was necessary to stabilize the spine against both the oscillations of the Bodyblade® and the reaction moment produced when pushing a heavy load in standing. In addition, the catch and throw of the medicine ball is a relatively complex activity that requires coordinated activation of muscles of the trunk and the limbs.

Abstract: The purpose of this study was to compare the amplitude of the electromyography (EMG) and the way that the abdominal muscles co-activated during the curl up and two traditional motor games: the wheelbarrow race and the hula-hoop. The EMG from the rectus abdominis, external oblique and internal oblique of nine healthy volunteers was recorded during the three tasks. People with histories of abdominal surgery, episodes of back pain or low back disorders were excluded. EMG amplitude was averaged and normalized to the maximum voluntary contraction. The two-way ANOVA (muscle/task) and the post hoc Tukey showed the differences in electrical activity for each muscle during the tasks and between muscles during each task. In the present study, the electrical activity during the motor games was greater than during the curl up exercise. Therefore, the motor games can be take into consideration as an alternative to condition the abdominal muscles. Although the wheelbarrow race produced a high level of abdominal coactivation, it principally activated the external oblique. No significant differences were found during the hula-hoop.

Abstract: The purpose of this study was to determine the effectiveness of four traditional motor games (�the tunnel�, �the chicken battle�, �the drunk� and �the wheelbarrow race�) for strengthening the abdominal muscles. Electromyography (EMG) was collected from rectus abdominis (RA), external oblique (EO), and internal oblique (IO) from twelve healthy volunteers during the performance of the games and the trunk curl-up exercise. The EMG amplitude was averaged and normalized using maximal voluntary isometric contractions. A two-way ANOVA (muscle / task) was used to compare the level of contraction activity and the way the abdominal muscles co-activated during the different tasks. For EO and IO, the EMG amplitudes during the games were equal or greater than the EMG amplitudes of the curl up. The wheelbarrow race produced the highest intensity of contraction for all muscles. The curl up principally activated RA and IO. On the other hand, the games activated the oblique muscles with higher intensity than RA. On the basis of these results, the motor games are effective for abdominal conditioning.