RESUMEN
OBJECTIVE: This test was designed to evaluate the effect of lower-limb dominance and non-dominance shuttle runs under load carriage during different exercise load at the same exercise intensity on the balance responses. METHODS: Ten healthy young males were joined in this experiment, they were (20.80±2.04) years old and (173.99±2.87) cm tall. In a randomized cross-over design, they performed four times shuttle runs under unilateral load carriage:20 m×5 at dominant side, 20 m×5 at non-dominant side, 20 m×10 at dominant side, 20 m×10 at non-dominant side respectively. Balance abilities were evaluated immediately and 20 minute post-exercise respectively, and R-R interval was recorded. RESULTS: The HR, EPOC and TRIMP for all exercise load were increased significantly after shuttle runs compared to rest (P<0.01), the EPOC and TRIMP for 20 m×10 shuttle runs were significantly higher than those for 20 m×5 shuttle runs at the dominant and non-dominant side (P<0.01). Compared to the rest, the instability indices (general, anteroposterior and mediolateral movement) for 20 m×5 and 20 m×10 shuttle runs immediately post-exercise at the dominant and non-dominant side were increased significantly (P<0.05), and the magnitude of the mediolateral movement for 20 m×10 shuttle runs was higher than that of 20 m×5 shuttle runs (P<0.05). While there were no obvious difference between the dominant and the non-dominant side (P>0.05), which showed symmetrical change. In addition, during 20 minute recovery, the balance ability for all exercise load was returned to the rest value (P>0.05). CONCLUSIONS: The shuttle runs could impair the trunk control ability immediately post-exercise, the magnitude of mediolateral movement was increased as the exercise load increased. The changes of balance responses were similar between the dominant and the non-dominant side, the dominant and the non-dominant side might show cross-effects.
