On the effect of repetitive loading on the spine of young elite athletes. Clinical and experimental studies

Abstract: Introduction: The human spine is exposed to many different loads during daily activities and especially during sporting activities. The spine has different biomechanical properties during the lifetime and thereby responds differently to repetitive and sudden loads. The correlation of differ-ent motions and load exposures to spine and back problems have not yet been fully clarified. Aim: To investigate the effect of repetitive loading of different magnitude and motion on the spine with both clinical and experimental studies. To investigate the prevalence of LBP and the amount and type of spinal abnormalities on MRI in the spine that young elite athletes in mogul skiing and long distance running are subjected to due to the repetitive loading in their sports compared to non-athletic controls. To investigate the failure and fatigue responses in young porcine Functional Spinal Units (FSU) due to repetitive loading. Methods and results: The prevalence of LBP and spinal abnormalities were investigated in two cross sectional studies, with young long distance runners and mogul skiers compared to matched control groups with questionnaires and MRI assessment. The results displayed significantly high-er lifetime LBP in runners (45%) than the corresponding controls (12%) while no significance was seen between the skiers (50%) and their control group (42%). The mogul skiers had signifi-cantly more MRI abnormalities in mean than the control group (7.3 vs 3.8, p<0.023) and no sig-nificant difference was seen between the runners and controls (5.6 vs 9.2). The fatigue and failure response of young porcine FSUs were investigated in two experimental motion settings. The results displayed that the FSUs were resilient towards the induced fatigue loading in both axial and flexion-extension motions. The endplate and the growth zone displayed corresponding histological and MRI changes and fractures as fatigue and failure responses. Conclusion: LBP is common among young athletes and the frequency of spinal abnormalities seem to increase with greater spinal load magnitude. Repetitive loading of the young porcine spine cause fatigue and failure responses mainly localized in the growth zone and the endplate.