Deadlift muscle force and activation under stable and unstable conditions.

The objective of this study was to compare the production of force and paraspinal muscle activity between deadlifts carried out in a standard way and with different instability devices (Bosu and T-Bow). Deadlifts involve the performance of muscle activities with dynamic and isometric characteristics. Thirty-one subjects participated voluntarily in the study. Initially, they performed an isometric test for 5 seconds in each condition. After that, they performed a set of 5 repetitions with 70% of the maximum isometric force obtained in each one of the previously evaluated conditions. During the isometric tests, records of electromyographic activity and force production were obtained, whereas during the dynamic tests, only the electromyographic activity was registered. The subjects produced more force and muscle activity on the stable surface than under the other conditions during the isometric test (p < 0.05), and the same differences in muscle activity were observed during the dynamic test (p < 0.05). These data show that the performance of deadlifts under stable conditions favors a higher production of maximum strength and muscle activity. Therefore, we conclude that the use of instability devices in deadlift training does not increase performance, nor does it provide greater activation of the paraspinal muscles, leading us to question their value in the performance of other types of exercises.