Mind–Muscle Connection: Limited Effect of Verbal Instructions on Muscle Activity in a Seated Row Exercise

Abstract

Verbal instruction increases electromyographic (EMG) activity in the first three repetitions of an exercise, but its effect on an entire exercise set until failure is unknown. Once there are changes in motor unit recruitment due to fatigue, the effect of verbal instructions can change during different intervals of a set. This study analyzed whether verbal instruction emphasized the contraction of back muscles (i.e., myoelectric activity) during initial, intermediate, and final exercise repetitions performed until failure. Twenty participants with little or no experience in strength training performed a seated row exercise with and without verbal instruction. Surface electrodes were fixed over the latissimus dorsi, teres major, biceps brachii, and posterior deltoid (PD) muscles. Myoelectric activity was computed by mean amplitude and by the median frequency. We analyzed data with repeated measures multivariate analysis of variance and found that, with verbal instruction, there was increased EMG mean amplitude in the latissimus dorsi (15.21%, p = .030) and reduced EMG mean amplitude in the PD (14.39%, p = .018) on initial repetitions. Other muscle EMG amplitudes did not change. On intermediate repetitions, there was reduced signal amplitude only in the PD (15.03%, p = .022). The verbal instruction did not interfere with signal amplitude on final repetitions nor in the median frequency throughout the series. Verbal instruction seems to have little effect on increasing myoelectric activity of these targeted muscles in an entire set of a resistance training.

Mind-Muscle Connection: Verbal Instructions Alter Electromyographic Activity for Elbow Flexors and Extensors During Co-Contraction Training

“…There was a slight, non-significant difference ( M = 6.79%) between conditions, implying a lack of effect for verbal instruction on this muscle. However, we should be cautious about drawing this conclusion, as previous studies showed that, when participants were closer to their maximal effort, verbal instructions were less effective (Snyder & Fry, 2012) or incapable of increasing EMG activity in the targeted muscle (Calatayud et al., 2016; Daniels & Cook, 2017; Fujita et al., 2019, 2020). A previous study showed that the highest level of TB activation during co-contractions was 74% (Maeo et al., 2013), similar to our observations in the present study.…”

“…This was the first study to analyze the mind-muscle connection during co-contraction training. The use of verbal instructions to direct attentional focus to target muscles in order to increase EMG activity levels was demonstrated before in conventional exercises of strength training (Calatayud et al., 2016; Fujita et al., 2020; Snyder & Fry, 2012; Snyder & Leech, 2009). These previous studies had shown that verbal instructions were capable of increasing the EMG activity of target muscle in moderate intensities when few repetitions were realized.…”

“…Mind-muscle strategies use verbal instructions (VI) to direct attentional focus to a determined movement or a specific muscle group contraction (Calatayud et al., 2016; Paoli et al., 2019; Snyder & Fry, 2012; Snyder & Leech, 2009). Past research has shown that the mind-muscle connection can increase EMG activity on target muscles during conventional exercises of strength training performed in moderate intensities when few repetitions are done (Calatayud et al., 2016; Fujita et al., 2020; Snyder & Fry, 2012; Snyder & Leech, 2009). All these previous studies used VI focusing internally, in which attention was directed to body segments during exercises (Marchant et al., 2009; Wulf & Prinz, 2001).…”

The Pre-Exhaustion Method Does Not Increase Muscle Activity in Target Muscle During Strength Training in Untrained Individuals

“…The EMG data were digitally filtered with a fourth-order zero-lag Butterworth filter (bandpass 10-500Hz). For analysis of MVIC the first and the last second were excluded (Fujita et al, 2020), as well as the first and the last repetition of the seated row sets, since these periods were more susceptible to mistakes in cadence and movement execution in the exercises (Gentil et al, 2007).…”

“…The versatility of strength training contains a comprehensive selection of exercises (single and multi-joint). Recent studies have identified different ways to increase muscle recruitment during strength training, including the use of verbal instructions (Fujita et al, 2019(Fujita et al, , 2020, exercise order (Gentil et al, 2007), and volume of repetitions (Paz et al, 2020). A possible strategy to increase muscle recruitment could be muscle pre fatigue, and in this sense muscle preexhaustion (PreEx) was proposed (Jones, 1970).…”