Agonist and antagonist EMG activity of neck muscles during maximal isometric flexion and extension at different positions in young healthy men and women

Issue title: Selected papers and Abstracts of the "XXXIVèmes Entretiens de Mèdecine Physique et Réadaptation", Isokinetics 2007: An update, Montpellier, France, March 2007

Article type: Research Article

Authors: Lecompte, J.^{a; d} | Maisetti, O.^{b; c} | Guillaume, A.^a | Skalli and, W.^d | Portero, P.^{b; c}

Affiliations: [a] Institut de Médecine Aérospatiale du Service de Santé des Armées (IMASSA), BP 73, 91223 Bretigny-sur-Orge, France | [b] Service de rééducation Neuro-Orthopédique, INSERM U731/UPMC, Hôpital Rothschild (APHP), 33 boulevard de Picpus, 75012 Paris, France | [c] UFR SESS/STAPS, Université Paris XII, 61 avenue du Général de Gaule, 94010 Créteil, France | [d] Laboratoire de BioMécanique, CNRS UMR 8005, ENSAM, 151 Boulevard de l'hôpital, 75013 Paris, France

Note: [] Address for correspondence: Pr. Pierre Portero, Service de Rééducation Neuro-Orthopédique Inserm UMR 731/UPMC, Hôpital Rothschild 33 Boulevard de Picpus 75012 Paris, France. Tel.: +33 140193097; Fax: +33 140193205; E-mail: [email protected]

Abstract: The aim of this study was to compare maximal isometric torque and EMG activity of neck flexors and extensors in flexed and extended positions between men and women. Twenty four non-trained young healthy subjects (12 men vs. 12 women) performed maximal isometric neck flexion and extension within 30° around the neutral position in a sitting posture using a modified isokinetic dynamometer. Surface EMG activity of sternocleidomastoid, scalenus, paraspinal and upper trapezius muscles was recorded bilaterally. Men exhibited higher normalized-to-lean body weight torque than women mainly during neck flexion (44%, P<0.001) compared to extension (18%, P<0.05). In addition, torque increased from extended to flexed positions in women only (+17%, P<0.001). This was associated with a decrease in EMG of neck extensors and upper trapezius muscles (from 35% to 20% and from 18% to 7%, P< 0.001, respectively) without changes in agonistic activity of neck flexors with neck position. In contrast, men displayed similar torque and muscle activation level within 30° of range of motion around the neutral position for both directions. These findings demonstrate gender-specific differences in neck function that was probably linked to higher coactivation level in antagonist muscles (neck extensors) and stabilizers (upper trapezius muscles).

Keywords: Neck, EMG, coactivation, isometric torque, gender

DOI: 10.3233/IES-2007-0268

Journal: Isokinetics and Exercise Science, vol. 15, no. 1, pp. 29-36, 2007