Many bodybuilders and bodybuilders already think so, and for many years, focusing on movement would allow a more qualitative muscular work. The underlying idea would be to improve the connection between the brain and the muscle in order to obtain a more efficient and effective recruitment of motor units. Does focusing on muscle action help to recruit your muscles ?
Indeed, several studies show that during a low or moderate strength training exercise (<50% of the 1RM), instructions to "focus on the movement achieved" or "to focus on the acting muscles of the movement" allowed to improve muscle activation. This would result in better recruitment of driving units without increasing the external load, which in areas such as rehabilitation could have a strong impact. But what if the intensity increases ? What is the relationship between load intensity and the ability to activate a muscle preferentially ?
L'étude réalisée
To answer this question, a team of Danish and Spanish researchers studied the impact of different instructions on muscle recruitment during a lying development. To do this, they asked 18 young men to carry out a development lying according to 3 different conditions, randomly : a normal lying developed (DC), a lying developed where it was asked to focus on the great pectoral (DC Pectoral), and a lying developed where it was asked to focus on brachial triceps (DC Triceps). The goal for the participants was to volontarily contract the muscles on which they had to focus. These 3 conditions were achieved at different intensities (20, 40, 50, 60 and 80% of the 1RM). Surface electromyography (EMG) was used to measure the electrical activity of the muscles involved.
Résultats & Analyses
The main results of this study show that from 20 to 60% of the 1RM, the muscle activation of the muscles studied is significantly higher in conditions where these muscles are selectively recruited by the participants compared to the normal condition. More simply, when the practitioner focuses on the contraction of the great pectorals, they are actually better recruited, the same is true with triceps (Fig 1). In addition, the preferential activation of one muscle was not done to the detriment of the other (e.g., when the large pectoral is more activated than normal, the brachial triceps is activated normally, or even more in some cases).
Figure1.Relationship between intensity (%1RM)and muscle activity by preferential activation.*Significant difference (p≤0.01).
However between 60 and 80% oft he 1RM, there seems to be a threshold ,since no difference was found. The intensity of the load can be such that the practitioners focus mainly on the movement of the bar. The human body can seek to recruit the minimum number of motor units needed to make a movement. It can also come from the level of the practitioners. In this study, the1RM of the practitioners was103±25kg, which means that the level among them was very heterogeneous. There maybe a relationship between the strength of athletes and their ability to target certain muscles during muscle contraction. A study published in 2012 had shown positive resultsat 80% of 1RM in American Division III footballers.
Applications pratiques
By focusing on either the large pectoral or the brachial triceps, the participants in this study were able to significantly and selectively increase the activation of these muscles at the lying developed, at low to moderate intensities. This study illustrates the constrained action hypothesis. Muscle activation is less when the athlete is focused on the result (external concentration) and greater when he is focused on the movement (internal concentration). These results are interesting in practice since it means that in rehabilitation, physical preparation or muscle strengthening, the conscious and voluntary involvement of the patient/ athlete/ client on the movement achieved will result in an increase in muscle activation, and thus ultimately, in again of efficiency and effectiveness. For the same external charge, an advanced practitioner will be able to recruit more motor units.
Of course, training is necessary to better control his muscle contractions, especially at high intensity, and it is possible to believe that a more experienced and stronger athlete will have a better mastery of this concept than a beginner. Nevertheless, it is still difficult to know where the internal concentration will begin depending on the intensity of the task and the profile of the practitioner.
References
Calatayud J, Vinstrup J, Jakobsen MD, Sundstrup E, Brandt M, Jay K, Colado JC and Andersen LL. Importance of mind-muscle connection during progressive resistance training. Eur J Appl Physiol, In Press, 2015.
Article extracted from : sci-sport.com