Sequential muscle activity and its functional role in the upper extremity and trunk during overarm t

Authors: Hirashima M.; Kadota H.; Sakurai S.; Kudo K.; Ohtsuki T.

Source: Journal of Sports Sciences, Volume 20, Number 4, 1 April 2002 , pp. 301-310(10)

Abstract:

The proximal-to-distal segmental sequence has been identified in many sports activities, including baseball pitching and ball kicking. However, proximal-to-distal sequential muscle activity has not been identified. The aims of this study were to establish whether sequential muscle activity does occur and, if it does, to determine its functional role. We recorded surface electromyograms (EMGs) for 17 muscles from the upper extremity and abdomen during overarm throwing and detected the onset and peak times as indices of muscle activity. The following electromyographic properties were commonly identified in the participants. First, sequential muscle activity was observed from the scapular protractors to the shoulder horizontal flexors and from the shoulder horizontal flexors to the elbow extensor, but not from the elbow extensor to the wrist flexor or forearm pronator. Secondly, the external oblique contralateral to the throwing arm became activated before the ipsilateral external oblique. This sequence is considered to be very effective for the generation of high force and energy in the trunk. Thirdly, the ipsilateral external oblique began its activity almost at foot strike. Finally, the main activity of the rectus abdominis appeared just before the point of release.

خلاصه ?Flatfoot in Children: How to Approach

Flatfoot in Children: How to Approach?

SM Javad Mortazavi*1, MD; Ramin Espandar2, MD; Taghi Baghdadi3, MD

1. Orthopedic Surgeon, Sports Medicine Research Center, University of Tehran/ Medical Sciences, Tehran,

IR Iran

2. Orthopedic Surgeon, Orthopedic Department, Imam Khomini Hospital, University of Tehran/ Medical

Sciences, Tehran, IR Iran

* Correspondence author.

Address: Sports Medicine Research Center, Al-e-Ahmad Highway, Tehran, IR Iran

E-mail: [e-mail]

 

 

Introduction

Flatfoot rarely causes disability, but it remains a major concern of parents. Children from the neonatal period to the preschool age are ordinarily brought to the general or the pediatric orthopedist because of their foot and gait problems, which may or may not be developmentally or clinically significant[1,2].