https://www.selleckchem.com/products/Temsirolimus.html Pooled risk of sustaining a concussion was more than three times greater in children with a previous concussion compared with those with no previous concussion (RR=3.64; 95% CI 2.68 to 4.96; p<0.0001; =90.55%). Unreported sex-stratified data precluded direct comparison of concussion risk in male versus female athletes. Previously concussed children have four times the risk of sustaining a concussion compared with those with no previous concussion history. This should be a consideration for clinicians in return to sport decision-making. Future studies examining subsequent recurrent concussion in youth sports must consider sex differences. Previously concussed children have four times the risk of sustaining a concussion compared with those with no previous concussion history. This should be a consideration for clinicians in return to sport decision-making. Future studies examining subsequent recurrent concussion in youth sports must consider sex differences. We aimed to determine the prevalence of low back pain (LBP) in sport, and what risk factors were associated with LBP in athletes. Systematic review with meta-analysis. Literature searches from database inception to June 2019 in Medline, Embase, Cumulated Index to Nursing and Allied Health Literature (CINAHL), Web of Science and Scopus, supplemented by grey literature searching. Studies evaluating prevalence of LBP in adult athletes across all sports. Eighty-six studies were included (30 732, range 20-5958, participants), of which 45 were of 'high' quality. Definitions of LBP varied widely, and in 17 studies, no definition was provided. High-quality studies were pooled and the mean point prevalence across six studies was 42%; range 18%-80% (95% CI 27% to 58%, I =97%). Lifetime prevalence across 13 studies was 63%; range 36%-88% (95% CI 51% to 74%, I =99%). Twelve-month LBP prevalence from 22 studies was 51%; range 12%-94% (95% CI 41% to 61%, I =98%). Comparison