OBJECTIVES: Judo is a popular martial art which is required the ability to balance and the strength of core muscle. The aim of this research was to assess the effect of core muscle strengthening on balance.

METHODS: This research was carried out among active competitors (n=13, between the ages of 10 and 15) of the Judo Sports Association of Zalaegerszeg, at the Zalaegerszeg Training Center of the Faculty of Health Sciences of the University of Pécs, from September to December in 2019 in Hungary. The following tests were used: Y-Balance Test, Standing Stork Test, Lumbar Motor Control Test, Sit Ups Test, Extensor Endurance Test, Core Muscle Strength and Stability Test. Group 1 (n=7) took part in 10 times balance training (1*40 min per week), Group 2 (n=6): 10 times balance training and 10 times core muscle strengthening training (2*40 min).

RESULTS: The results of the balance tests showed improvement in both groups but there was no significant difference between the groups (Standing Stork Test: right leg: p^group1 =0.039; p^group2=0.032; left: p^group1=0.010; p^group2=0.009). Sit Ups Test, Core Muscle Strength and Stability Test showed significant improvement only in the second group (p^SUT=0.009, p^CMSST=0.019). In the Lumbal Motor Control Test Group 2 showed significant improvement in both leg with and without visual control (p<0,05), while Group 2 had only 3 significant results out of 4. In case of the Extensor Endurance Test: Group 1 from 110.7 sec to 131.0 sec, p=0.011; Group 2 from 66.2 sec to 122.0 sec, p=0.013.

CONCLUSIONS: The core muscle showed significant development in both groups but the rate of improvement was greater in the second group. However we found the same level of improvement in the balance, there was no significant difference between the groups. Overall we found that the complex therapy can be more effective.