The occurrence of flexion-relaxation phenomenon in elite cyclists during trunk forward bending

Abstract

Flexion-relaxation phenomenon (FRP) is a well-knownphenomenon in spinal extensor muscles. According to the literature, prolongedflexed posture leads to creepphenomenon and affects the active and passive neuromuscular control of thespinal column. The purpose of this study was to investigateFRP occurrence in elite cyclists that prolonged flexion posture is an integralpart of their professional life. Their muscles’ contractionpattern during forward bending was also compared. Electromyography(EMG) was recorded during flexion andextension from standing position in thoracic erector spinae (TES), lumbarerector spinae (LES) and gluteus maximus (Gluteus max) in 15 healthy male elite cyclists. In addition, thekinematic data related to the trunk angles were simultaneously recorded by amotion analysis system. Two-way ANOVA was used to assess the effects of musclegroup and direction of movement on maximum amplitude of EMG activity. Among 15 cyclists, FRP was detectable in 60%, 87%and 73% of the participants in TES, LES and Gluteus max, respectively, and happened between 74% and 82% of the trunk flexion. There was nostatistically significant difference in onset and offset of muscles FRP. Despite prolonghyper kyphotic posture, FRP was identifiable in TES, LES and Gluteus max muscles of elitecyclists