Roughly about 40 % of adult population has experienced low back pain (LBP). LBP represents a complex public health problem, since 85 % of sufferers endure non-specific pain (pain of unknown etiology). Intra-abdominal pressure (IAP) therefore plays an important role, since it, when elevated, improves stability of lumbar spine. Main purpose of this magister thesis is to estimate mechanism of stabilisation of lumbar spine during some motor tasks, connected to carrying heavy objects, and to evaluate IAP and its connection to these tasks and usefulness of measurement device for measuring lateral abdominal force (LAF). 27 subjects performed 6 different tasks (maximal IAP while standing upright (STSma), maximal deliberate isometric force while lifting object from navel height next to the body (Oma) and away from the body (Sma), lifting light object from navel height next to the body (O10) and away from the body (S10), lifting heavy object from navel height next to the body (O10) and away from the body (S10). Changes in IAP were estimated with help of LAF and the start time of lifting with tensiometric force plate. Results were statistically analysed with SPSS 22 program (IBM Corp, New York, USA). No statistically significant differences were found between IAP (or LAF) during lifting weights close and away of centre mass of the body, although size of weight influenced IAP (higher the weight, bigger the LAF). Percentage of IAP use between subjects was compared. It was concluded, that IAP is not influenced by absolute power of the subject but rather by correct mechanism of applied high pressure. It has been shown that LAF – measuring device produces reliable results, which are independent of subjects’ body fat percentage. It shows that device could be used for teaching IAP production, monitoring lifting mechanism and it could serve as non-invasive alternative for invasive intra-abdominal monitoring of IAP.