The purpose of this dissertation was to investigate the occurrence, nature, severity, injury mechanisms and risk factors of musculoskeletal disorders (MSDs) including low back pain (LBP) and medical discharge in male Finnish conscripts. Furthermore, the effectiveness of a neuromuscular exercise (NME) and counseling program in the prevention of acute musculoskeletal injuries, and LBP and disability was investigated during military training. The participants were an unselected population-based cohort of Finnish young males (N=2057) that were engaged in high level of physical activity during their military service. The key finding considering epidemiologic studies was the strong predictive association of poor physical fitness for MSDs and military discharge in previously healthy conscripts. The intervention program, designed enhance conscripts’ motor and muscular performance and increase awareness of military tasks that could lead to acute injuries and LBP, decreased acute ankle injuries by 66% and reduced the number off-duty days due to LBP by 58% in the intervention companies compared to the controls.