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Importance of mind-muscle connection during progressive resistance training

DOI:10.1007/s00421-015-3305-7
Authors:
Joaquin Calatayud at University of Valencia
Joaquin Calatayud
Jonas Vinstrup at National Research Centre for the Working Environment
Jonas Vinstrup
Markus Due Jakobsen at National Research Centre for the Working Environment
Markus Due Jakobsen
Emil Sundstrup at National Research Centre for the Working Environment
Emil Sundstrup
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Abstract and Figures

Purpose: This study evaluates whether focusing on using specific muscles during bench press can selectively activate these muscles. Methods: Altogether 18 resistance-trained men participated. Subjects were familiarized with the procedure and performed one-maximum repetition (1RM) test during the first session. In the second session, 3 different bench press conditions were performed with intensities of 20, 40, 50, 60 and 80 % of the pre-determined 1RM: regular bench press, and bench press focusing on selectively using the pectoralis major and triceps brachii, respectively. Surface electromyography (EMG) signals were recorded for the triceps brachii and pectoralis major muscles. Subsequently, peak EMG of the filtered signals were normalized to maximum maximorum EMG of each muscle. Results: In both muscles, focusing on using the respective muscles increased muscle activity at relative loads between 20 and 60 %, but not at 80 % of 1RM. Overall, a threshold between 60 and 80 % rather than a linear decrease in selective activation with increasing intensity appeared to exist. The increased activity did not occur at the expense of decreased activity of the other muscle, e.g. when focusing on activating the triceps muscle the activity of the pectoralis muscle did not decrease. On the contrary, focusing on using the triceps muscle also increased pectoralis EMG at 50 and 60 % of 1RM. Conclusion: Resistance-trained individuals can increase triceps brachii or pectarilis major muscle activity during the bench press when focusing on using the specific muscle at intensities up to 60 % of 1RM. A threshold between 60 and 80 % appeared to exist.
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1 3
Eur J Appl Physiol (2016) 116:527–533
DOI 10.1007/s00421-015-3305-7
ORIGINAL ARTICLE
Importance of mind‑muscle connection during progressive
resistance training
Joaquin Calatayud1,4 · Jonas Vinstrup1 · Markus Due Jakobsen1,2 · Emil Sundstrup1,2 ·
Mikkel Brandt1,3 · Kenneth Jay1,2,4 · Juan Carlos Colado4 · Lars Louis Andersen1,3
Received: 27 May 2015 / Accepted: 27 November 2015 / Published online: 23 December 2015
© Springer-Verlag Berlin Heidelberg 2015
activity of the other muscle, e.g. when focusing on activating
the triceps muscle the activity of the pectoralis muscle did not
decrease. On the contrary, focusing on using the triceps mus-
cle also increased pectoralis EMG at 50 and 60 % of 1RM.
Conclusion Resistance-trained individuals can increase
triceps brachii or pectarilis major muscle activity during
the bench press when focusing on using the specific muscle
at intensities up to 60 % of 1RM. A threshold between 60
and 80 % appeared to exist.
Keywords Muscle activation · Internal focus · Strength
training · Bodybuilding
Abbreviations
EMG Electromyography
pectoralis Pectoralis major
Triceps Tricepsbrachii
1RM One-maximum repetition
RMS Root-mean-square
Introduction
For years bodybuilders have used the principle of focusing
on contracting specific muscles to enhance muscle size and
increase ‘the pump’. Indeed, the American College of Sports
Medicine considers the technique of voluntarily squeez-
ing the muscles as a way to provide self-resistance during
resistance training (Ratamess 2011). However, scientific lit-
erature evaluating the effectiveness of selectively focusing
on specific muscles during exercise performance is scarce
(Snyder and Fry 2012). Different verbal instructions have
provided greater EMG response during maximal isometric
contractions of both the elbow flexors and leg muscles (Sah-
aly et al. 2003). Instructions to selectively activate specific
Abstract
Purpose This study evaluates whether focusing on using
specific muscles during bench press can selectively activate
these muscles.
Methods Altogether 18 resistance-trained men participated.
Subjects were familiarized with the procedure and performed
one-maximum repetition (1RM) test during the first session.
In the second session, 3 different bench press conditions were
performed with intensities of 20, 40, 50, 60 and 80 % of the
pre-determined 1RM: regular bench press, and bench press
focusing on selectively using the pectoralis major and triceps
brachii, respectively. Surface electromyography (EMG) sig-
nals were recorded for the triceps brachii and pectoralis major
muscles. Subsequently, peak EMG of the filtered signals were
normalized to maximum maximorum EMG of each muscle.
Results In both muscles, focusing on using the respective
muscles increased muscle activity at relative loads between
20 and 60 %, but not at 80 % of 1RM. Overall, a threshold
between 60 and 80 % rather than a linear decrease in selec-
tive activation with increasing intensity appeared to exist. The
increased activity did not occur at the expense of decreased
Communicated by William J. Kraemer.
* Lars Louis Andersen
lla@nrcwe.dk
1 National Research Centre for the Working Environment,
Lersø Parkalle 105, Copenhagen, Denmark
2 Institute of Sports Science and Clinical Biomechanics,
University of Southern Denmark, Odense, Denmark
3 Physical Activity and Human Performance Group, SMI,
Department of Health Science and Technology, Aalborg
University, Aalborg, Denmark
4 Research unit in Sport and Health, Department of Physical
Education and Sports, University of Valencia, Valencia, Spain
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Therefore, the first step is to understand whether or not the internal focus increases muscle activation compared to an external focus with the same relative load. The literature is in general favourable to this, as reviewed over the years [26,27], even though the experience of the subjects [74], the muscles involved [75], the movement velocity [76], or the load [77,78] may affect the results. The studies report greater muscle activation with an internal focus on several muscles during different exercises, such as pectoralis major during bench press [77], biceps brachii during biceps curl [79], quadriceps during leg extension [80], or posterior thigh muscles during the squat [78]. ...
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... First, more experienced may be more able than less experienced people to increase muscle activation [74]. Second, very high external loads require yet higher muscle activation, so it may be difficult to further recruit muscles compared to light loads, where more marked increments in muscle activation were observed [77]. However, experienced subjects were able to increase muscle activation of the triceps brachii during bench press [75] or gluteus maximus and biceps femoris during the squat [78] with both 50% and 80%1-RM. ...
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... In healthy individual, the internal focus (also called mindmuscle connection) may increase muscle activity, especially at lowmoderate intensities. 46 In addition, focusing on maximal contraction of a muscle group (e.g., internal focus) during strength exercise has been reported to be superior to increase muscle thickness than external focus (or simply moving the load during strength exercise). 47 In contrast, external focus or distraction manoeuvres using dual tasks have been reported to improve muscular endurance. ...
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Influence of proprioceptive feedback on the firing rate and recruitment of motoneurons
Article
We investigated the relationships of the firing rate and maximal recruitment threshold of motoneurons recorded during isometric contraction with the number of spindles in individual muscles. At force levels above 10% of maximal voluntary contraction, the firing rate was inversely related to the number of spindles in a muscle, with the slope of the relationship increasing with force. The maximal recruitment threshold of motor units increased linearly with the number of spindles in the muscle. Thus, muscles with a greater number of spindles had lower firing rates and a greater maximal recruitment threshold. These findings may be explained by a mechanical interaction between muscle fibres and adjacent spindles. During low-level (0% to 10%) voluntary contractions, muscle fibres of recruited motor units produce force twitches that activate nearby spindles to respond with an immediate excitatory feedback that reaches maximal level. As the force increases further, the twitches overlap and tend towards tetanization, the muscle fibres shorten, the spindles slacken, their excitatory firings decrease, and the net excitation to the homonymous motoneurons decreases. Motoneurons of muscles with greater number of spindles receive a greater decrease in excitation which reduces their firing rates, increases their maximal recruitment threshold, and changes the motoneuron recruitment distribution.
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Effect of Verbal Instruction on Muscle Activity During the Bench Press Exercise
Article
Recent research suggests that humans have some ability to selectively activate or relax some muscles during isometric or dynamic muscle actions without changing posture or position. This study sought to reveal whether trained athletes could isolate either the pectoral or triceps muscles, respectively, at different intensities when given verbal technique instruction. Eleven male Division III football players performed 3 sets of bench press at 50% 1-repetition max (1RM) and 80% 1RM while electromyographic (EMG) activity was recorded from the pectoralis major (PM), anterior deltoid (AD), and triceps brachii (TB). In the first set, the subjects performed the exercise without instruction. In the second set, the subjects were given verbal instructions to use only chest muscles. In the third set, the subjects were instructed to use only triceps muscles. Mean normalized root mean square EMG activity was calculated during 3 repetitions in each condition. Repeated-measures analysis of variance was used to detect differences from the preinstruction condition, with significance set to p ≤ 0.017 as indicated by a Bonferroni correction for multiple comparisons. During the 50% max lift with verbal instructions to focus on chest muscles, PM EMG activity increased by 22% over preinstruction activity (p = 0.005), whereas AD and TB activities were statistically unchanged. When the subjects were instructed to focus on only the triceps muscles, PM returned to baseline activity, whereas TB activity was increased by 26% (p = 0.005). When the lift was increased to 80% max, PM and AD activities were both increased with verbal instructions to use only chest muscles. The TB activity was unchanged during the 80% lifts, regardless of instructions. In conclusion, it is found that verbal technique instruction is effective in shifting muscle activity during a basic lift, but it may be less effective at higher intensities.
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Voluntary Increase in Latissimus Dorsi Muscle Activity During the Lat Pull-Down Following Expert Instruction
Article
It has been observed anecdotally that while performing the multijoint lat pull-down exercise, novice strength trainers often rely on the elbow flexors to complete the movement rather than fully utilizing the relevant back muscles such as the latissimus dorsi (LD) and teres major (TM). The primary aim of the study was to determine whether specific technique instruction could result in a voluntary increase in LD and TM electromyographic (EMG) activity with a concurrent decrease in the activity of the biceps brachii (BB) during the front wide-grip lat pull-down exercise. Eight women with little or no background in strength training were asked to perform lat pull-down exercise with only basic instruction, performing 2 sets of 3 repetitions at 30% max. After a brief rest, subjects then performed the same 2 sets of 3 repetitions following verbal technique instruction on how to emphasize the latissimus while de-emphasizing the biceps. EMG activity of the LD, TM, and BB were recorded, converted to root mean square, and normalized to the maximum isometric EMG (NrmsEMG). A significant increase was seen in Nrms EMG in the LD (p = 0.005) from the average of preinstruction NrmsEMG to the average of postinstruction NrmsEMG. No significant differences were observed between pre- and postinstruction muscle activity in the BB or TM. The results show that untrained individuals can voluntarily increase the activity of a specified muscle group during the performance of a multijoint resistance exercise, but the increase probably does not represent "isolation" of the muscle group through voluntary reduction of activity in complementary agonist muscles.
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