Dominant and non-dominant leg press training induce similar contralateral and ipsilateral limb training adaptations with children.

Cross-education has been extensively investigated with adults. Adult studies report asymmetrical cross-education adaptations predominately after dominant limb training. The objective of the study was to examine unilateral leg-press (LP) training of the dominant or non-dominant leg on contralateral and ipsilateral strength and balance measures. Forty-two youth (10-13 years) were placed (random allocation) into a dominant (n=15) or non-dominant (n=14) leg-press training group or non-training control (n=13). Experimental groups trained 3 times per week for 8 weeks and were tested pre-/post-training for ipsilateral and contralateral 1-repetition maximum (RM) LP, knee extensors (KE) and flexors (KF) maximum voluntary isometric contractions (MVIC), countermovement jump (CMJ), triple hop test (THT), elbow flexors (EF) MVIC and handgrip MVIC, as well as Stork and Y balance test. Both dominant and non-dominant LP training significantly (p<0.05) increased both ipsilateral and contralateral lower body strength (LP 1RM [Dominant:59.6-81.8%; Non-dominant:59.5-96.3%], KE MVIC [Dominant:12.4-18.3%; Non-dominant:8.6-18.6%], KF MVIC [Dominant:7.9-22.3%; Non-dominant:non-significant-3.8%]), and power (CMJ: Dominant:11.1-18.1%; Non-dominant: 7.7-16.6%]) with the exception that non-dominant LP training demonstrated a non-significant change with the contralateral KF MVIC. Other significant improvements were with non-dominant LP training on ipsilateral EF 1RM (6.2%) and THT (9.6%). There were no significant changes with EF and handgrip MVIC. The contralateral leg Stork balance test was impaired following dominant LP training. KF MVIC exhibited the only significant relative post-training to pre-training (post-test/pre-test) ratio differences between dominant versus non-dominant LP cross-education training effects. In conclusion, children exhibit symmetrical cross-education or global training adaptations with unilateral training of dominant or non-dominant upper leg.