Honkanen T, et al. - During a 5-year follow up among Finnish Air Force (FINAF) fighter pilots, researchers investigated the differences in muscle cross-sectional area (CSA) and composition of the psoas and paraspinal muscles. They observed an increase of 8% in the mean CSA of the paraspinal muscles at L3–4 level and 7% at L4–5 level during the 5-year period. No change in muscle composition appeared during the follow-up period. A positive correlation was noticed between the paraspinal and psoas muscles' CSA and overall maximal isometric strength at the baseline. Although, no correlation between low back pain and muscle composition or CSA was reported.