OBJECTIVES: The study aimed at testing the efficiency of a six-week-long core training program among primary school students.

METHODS: The research type was quantitative, prospective investigation. The study was carried out from May to June 2019. The sample comprised of 20 persons (n=20) and a non-randomized sampling technique was used. The participants were 8th-grade primary school students with the mean age of 14 years. We carried out the trunk stabilization training for six weeks, twice a week, for 45 minutes at every turn. Trainings were performed exclusively by the use of the tool of Totalbody Resistance Exercise (TRX). The applied testing methods were as follows: 1) trunk stabilization test (sports specific plank test); 2) dynamic balance test (Y balance test on the upper limb, star balance test on the lower limb); 3) lumbar motor control test (Stabilizer Pressure, Biofeedback device).

RESULTS: Core muscle strength improved significantly by the effect of the exercise program (before:138sec, after:176sec; p<0.001.) Significant improvement was observed in all three directions on the right side (lateral, superomedial, inferomedial) (p< 0.05). Improvement on the left was also significant (p<0.05) except for one direction (superomedial: p=0.59). Dynamic balance improved significantly in the lower limb on the right side in all eight directions (anterior, anterolateral, lateral, posterolateral, posterior, posteromedial, medial, anterimedial). Improvement on the left side was also significant (p<0.05) except for two directions (medial: p=0.08; anteromedial: p=0.154). Lumbar motor control significantly improved on both sides (p<0.05) – right side before: 8.25Hgmm, after: 5.73Hgmm; left side before: 8.15Hgmm, after: 5.63Hgmm.

CONCLUSIONS: Core training with TRX tool effectively influenced the fitness of the trunk muscles of children, the stability of joints in the upper and lower limbs, and the lumbar motor control. In order to achieve the physical fitness in children, our exercise program proved to be effective.