OBJECTIVES:Accurately measuring speed and acceleration during walking, running and sprinting has important implications for rehabilitation, planning training and talent identification in sporting and clinical populations. Light detection and ranging laser technology provides a continuous stream of distance data. It has the potential to allow rapid and precise measurement and may be advantageous compared with discrete methods of assessment, such as stopwatches and timing gates, which may be inaccurate over short distances. Therefore, the aim of this study was to assess the validity of a novel, low-cost and easy to implement laser-based system during walking and running trials. DESIGN:Cross-sectional study. METHODS:Thirty-two healthy adults performed walking and running trials from flying and static starts while monitored concurrently with reference standard three-dimensional motion analysis and laser systems. Velocity was calculated over short (0.5m) and longer (3m) intervals using both systems. Validity was assessed using absolute agreement intraclass correlation coefficients (ICC2,1), mean absolute errors, Pearson's correlations and regressions and Bland-Altman plots. RESULTS:All intraclass correlation coefficients and correlations were excellent (ICC>0.88, R>0.89). For the longer interval, all mean absolute errors were <0.03m/s (0.24-1.31%). Slightly higher mean absolute error values were reported for the shorter interval (3.16-5.10%), with the highest error of 0.184m/s evident for the flying start running trial. CONCLUSIONS:These results indicate that a low-cost and accessible laser system can be used to accurately assess walking and running speed. To aid implementation and further research, freely available hardware design descriptions and downloadable software can be accessed at www.rehabtools.org/LIDAR.