Influence of load knowledge in resistance training on rapid force production, muscle activation and strength gains

Résumé

The purposes of this thesis are to investigate the effect of lack of load knowledge during a strength training exercise (bench press throw) on kinematic and electromyographic responses, and the adaptations entailed after a training intervention using unknown loads. The major findings of this thesis include: (1) lack of load knowledge entailed greater power outputs and rate of force development in the early phases of concentric-only bench press throws, without affecting neither peak power nor peak rate of force development; (2) when lifting unknown loads, anterior deltoid activity showed increased activity both prior to movement onset and in the early time intervals after movement onset, as well as pectoralis major activity were greater in the early time intervals after movement onset when using unknown loads; (3) lack of load knowledge did not influence antagonist muscles activity during concentric-only bench press throws; (4) after a 4-weeks training program, the unknown loads training group showed greater power output improvements in the early phases of the bench press throw exercise, independently of the load (30, 50 and 70% of 1 RM) used; (5) the unknown load training group showed increases in handball throwing velocity (7 m standing and 9 m jumping throw) after the 4-weeks training period. The results of this thesis indicate that absence of load knowledge is a useful stimulus to elicit greater explosive force production and muscle activation. In addition, continue exposure to these unknown loads leads to greater improvements both in power output and in specific athletic performance.