The aim of this pilot study was to examine whether differences existed in spinal kinematics and trunk muscle activity in cyclists with and without non-specific chronic low back pain (NSCLBP). Cyclists are known to be vulnerable to low back pain (LBP) however, the aetiology of this problem has not been adequately researched. Causative factors are thought to be prolonged forward flexion, flexion-relaxation or overactivation of the erector spinae, mechanical creep and generation of high mechanical loads while being in a flexed and rotated position. Nine asymptomatic cyclists and nine cyclists with NSCLBP with a flexion pattern disorder primarily related to cycling were tested. Spinal kinematics were measured by an electromagnetic tracking system and EMG was recorded bilaterally from selected trunk muscles. Data were collected every five minutes until back pain occurred or general discomfort prevented further cycling. Cyclists in the pain group showed a trend towards increased lower lumbar flexion and rotation with an associated loss of co-contraction of the lower lumbar multifidus. This muscle is known to be a key stabiliser of the lumbar spine. The findings suggest altered motor control and kinematics of the lower lumbar spine are associated with the development of LBP in cyclists. (C) 2004 Elsevier Ltd. All rights reserved.