We used RUSI (rehabilitative ultrasound imaging) for measurement of abdominal and back muscle in different loading modes. Methods: We used diagnostic ultrasonography imaging for taking linear measurement of trunk muscles. We measured anterioposterior (AP) dimensions of lateral abdominal wall muscles- m. OE, m.OI, m.TrA and cross-section area (CSA) of lumbar m. multifidus. We compared two groups of sports-floorball players and sportsman using climbing and hanging (climbers, aerialists). We measured positions with compressive force (kneeling on all four with lifted knees) and with traction load (hang with upper limbs with flexion of lower limbs-with leg support and without). Study is made on 50 volunteers. Results: The pattern of thickness of abdominal muscles is same in all positions in both groups. The lowest is always AP thickness of m. TrA, wider is m. OE and the widest always m. OI. The resting thickness are in both groups almost in all cases the lowest. AP thickness in m. TrA in floorball players is only exception, there is lowest in hang without legs support. In all other case sis resting position always lowest. For m. OE are results same for both climbers and floorball players-the lowest thickness is in hang with legs support (floorball players 0,84 cm, climbers 0,87), greater activationis...