Concurrent EMG feedback acutely improves strength and muscle activation

Abstract

The purpose of this study was to investigate the acute effects of electromyographic (EMG) feedback on muscle activation and strength during maximal voluntary concentric and eccentric muscle actions. 15 females performed two sets of three lengthening and three shortening maximal voluntary isokinetic knee extensions at 20° s(-1) over 60° range of motion. After the first set, subjects were randomized to either a control group (n = 8) or a feedback group (n = 7). In the second set, the control group performed tasks identical to those in the first set, whereas the feedback group additionally received concurrent visual feedback of the EMGrms from Vastus Medialis (VM). Knee extensor strength and EMG activation of VM, Vastus lateralis (VL) and hamstrings (HAM) were measured during the MVCs. Analyses were performed separately in a 1 s preactivation phase, a 1 s initial movement phase and a 1 s late movement phase. EMG feedback was associated with significantly higher knee extensor strength in all phases (20.5% p < 0.05, 18.2% p < 0.001 and 19% p < 0.001, respectively) for the eccentric MVCs and in the preactivation phase (16.3%, p < 0.001) and initial movement phases (7.2%, p < 0.05) for concentric MVCs. EMG feedback from VM further improved activation in VM and HAM but not VL. These findings suggested that concurrent visual EMG feedback from VM could acutely enhance muscle strength and activation. Before recommending implementation of EMG feedback in resistance training paradigms, the feedback parameters needs to be optimized and its long-term effects needs to be scrutinized.

Effect of augmented verbal and visual feedback on efficiency in skiing teaching

“…In summary, the teachers in both experimental groups adapted their feedback to the criteria of efficiency marked by the theoretical model. Hence, they complemented explanations with demonstrations of errors and prescriptive information, which predominated over simple description or evaluation of the action (Vernetta & López-Bedoya, 1998); they emphasized the predominance of positive over negative affectivity (Koka & Hein, 2005;Viciana, et al, 2007); they directed information individually to the students in a better way (Archer-Kath, et al, 1994); their feedback was mainly centred on the specific task (Fredenburg, Lee, & Solmon, 2001;Moreno & Del Villar, 2004); they ensured that they gave information to the students when they were standing in the right position to make the students see and hear their instructions correctly (Magill, 2010;Sáenz-López, 1997); they delivered feedback not only communicating actions to the students verbally, but also adding visual demonstrations (Crowell, et al, 2012); they avoided delay in delivering feedback, providing it immediately after the task and even concurrently when the task permitted it, depending on its simplicity or the speed of execution (Ekblom & Eriksson, 2012;Eriksson, et al, 2011); they ensured that all the students understood the information given, so promoting reflection on a participative and meaningful learning process (Hodges & Franks, 2002;Lee, 1996); and finally, they focused on the primary errors in the task (usually committed with the legs or skis) and how they affect the movement rather than the secondary ones (committed with the arms and upper part of the body), paying attention mainly to the principal aspects of the action (Wulf, et al, 2002).…”

Novos Conceitos Do Treinamento De Força Para a Fisioterapia

“…E ainda a capacidade de gerar estresse metabólico e o recrutamento de fibras musculares esqueléticas (FUJITA et al, 2007;SUGA et al, 2012). (NG et al, 2008;EKBLOM;ERIKSSON, 2012).…”

Use of Visual Feedback During Jump-Squat Training Aids Improvement in Sport-Specific Tests in Athletes

“…From a motor learning standpoint, it has been stated that instant feedback during exercise can have a substantial contribution to athletic performance (15). In this regard, many studies have investigated the effectiveness of instant feedback to maximize performance during the exercise itself (1,2,7,12,16,27).…”

“…For instance, Hopper et al (12) examined the influence of power production feedback during the leg press exercise in elite field-hockey players, where two groups of players were tested for peak power during a both feedback and non-feedback condition Results show that both groups had higher power production during the feedback condition (group 1: No-feedback = 685.4 ± 65.7 W and Feedback = 698.8 ± 64.8 W, group 2: No-feedback = 743.3 ± 103.5 W and Feedback = 756.0 ± 110.6 W, p = 0.027). Favorable findings for the use of feedback have also been demonstrated when comparing muscle activation and strength during concentric and eccentric muscle actions via EMG feedback (7).…”