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Influence of Trunk Curl-Up Speed on Muscular Recruitment

Vera-Garcia, Francisco J1; Flores-Parodi, Belén2; Elvira, José L L1; Sarti, M Ángeles3

Journal of Strength & Conditioning Research: May 2008 - Volume 22 - Issue 3 - pp 684-690
doi: 10.1519/JSC.0b013e31816d5578
Original Research

Although exercise speed is an acute variable to prescribe abdominal strengthening programs, current literature lacks 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 ± 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 curl-up 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). Statistical analyses 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 C4 to 49.6% of MVICs at Cmax) and internal oblique (ranged from 19.2% of MVICs at C4 to 48.5% of MVICs at Cmax) were the most active analyzed muscles 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-up speed 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.

1Área de Educación Física y Deportiva, Universidad Miguel Hernández de Elche, Elche (Alicante), Spain; 2Departamento de Ciencias de la Actividad Física y del Deporte, Universidad Católica San Antonio de Murcia, Murcia, Spain; 3Departamento de Anatomía y Embriología Humana, Universitat de València, València, Spain

Address correspondence to Francisco José Vera-García, fvera@umh.es.

© 2008 National Strength and Conditioning Association