Effects of Attentional Focus on Repetitions-to-Failure and Motor Unit Excitation During Submaximal Bench Press Performance

Attentional focus strategies refer to the use of cues or other stimuli to enhance an individual’s concentration for the purpose of improving performance within a given task. PURPOSE: To examine the effects of an internal (INT), external proximal (EPr), and external distal (ED) method of attentional focus on motor unit excitation and repetitions-to-failure (RTF) at a submaximal load. METHODS: Twenty-five recreationally active males (n=16) and females (n=9) volunteered to participate. The study was a repeated measures, randomized design and split into four days. Day one consisted of the completion of a one-repetition maximum (1RM) bench press test. The subsequent days consisted of one working set at 85% of the individuals 1RM performed until failure. For each day, a specific attentional focus strategy was given by auditory cues (i.e., INT, EPr, ED) with the individual instructed to focus solely on the cue. Motor unit recruitment of the anterior deltoid, pectoralis major, and triceps brachii was measured, via electromyography (EMG), for each repetition for all interventions. EMG, for each muscle group, for the final three repetitions of each condition were averaged and then divided by their respective maximum voluntary contraction to be reported as a percentage. A 1 x 3 repeated measures analysis of covariance, with a Bonferonni post-hoc, was conducted to determine differences between attentional focus conditions (a priori alpha = 0.05). RESULTS: Results indicated no differences for motor unit recruitment (chest: p = 0.59; triceps: p = 0.50; deltoids: p = 0.17) or RTF (p = 0.89) among the three conditions. The INT cue, as compared to EPr and ED, elicited a ~5-10% average increase in chest and triceps brachii motor unit excitation, despite an average of one less repetition. All effect sizes were deemed small or trivial, except for RTF between INT and ED which elicited a borderline moderate effect size (ES=0.55). CONCLUSIONS: These findings support previous literature demonstrating increases in motor unit excitation with an internal attentional focus. However, this strategy may place a greater demand on the targeted musculature to complete a given task; thus, decreasing performance (i.e., less RTF)