Effect of attentional focus on squats on lactate production and rating of perceived exertion in trained men

The aim of this study was to investigate the effect of internal focus (IF) and external focus (EF) on lactate production and the perception of perceived exertion in the squat in strength trained-men. Methods: Thirteen men with experience in strength training (age =22.61 ± 1.19 years; height = 180 ± 6.55 cm; body mass = 79.38 ± 5.57 kg; BMI = 24.56 ± 2.11 kg·m-2; Squat = 129 ± 20 kg) performed two sessions, separated by one week, comprising 3 sets of 10 repetitions of the back squat with one minute of rest between sets. During the IF protocol participants were instructed to focus on tightening the quads during all repetitions, while participants in the EF were instructed to focus on lifting the barbell. Blood lactate samples were collected before and at immediately after each of the 3 sets, as well as 15 minutes after the last set. Additionally, the rating of perceived exertion (RPE) was evaluated using the OMNI-RES scale immediately after the completion of each session. Results: Significant increases were found in the IF protocol at the end of each of the 3 sets, with significant effect sizes (1ª set, P= .000, d= 2.66; 2ª set, P= .000; d= 3.14; 3ª set, P= .000, d= 3.50), as in the EF protocol (1ª set, P= .001, d= 2.24; 2ª set, P= .000, d= 3.35; 3ª set, P= .000; d= 3.67). However, there were no significant inter-group differences between pre and any set (1ª set, P=0.951, d=0.03; 2ª set, P=0.239, d=0.47; 3ª set, P=0.435, d=0.31, respectively). Additionally, the perceptions on the RPE scale were higher in the FI (P= 0.032; d = 0.47). Conclusions: Findings suggest that the application of IF may indirectly contribute to muscle hypertrophy in multi-joint lower limb exercises, due to the increase in RPE values and the existing correlation with lactate production. Keywords: Mind-muscle, muscle hypertrophy, internal focus, mind-muscle connection, resistance training