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Attentional focusing instructions influence quadriceps activity characteristics but not force production during isokinetic knee extensions

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Abstract

The attentional focus emphasised in verbal instruction influences movement and muscle recruitment characteristics, with an external focus (onto movement effects) typically benefiting performance. However, contrasting findings suggest either a selective isolation or spreading activation effect on associated muscles as a result of internally focused instruction (movement characteristics). In the present experiment, participants completed maximal isokinetic concentric leg extension exercise using internally (muscle specific: vastus medialis oblique) or externally (outcome specific) focused instructions. Integrated Electromyography (iEMG) of the vastus lateralis, vastus medialis oblique and rectus femoris muscles was obtained in addition to knee extensor torque. There were no differences in torque production between conditions. Externally focused instruction produced significantly lower iEMG magnitude across muscles, whereas an internal focus produced the greatest activity but with no evidence of a selective isolation effect of the vastus medialis oblique. The muscle-specific internal focus of attention resulted in a spreading activation effect, such that activity is elevated in muscles not within the focus of attention. Whilst an external focus did not improve performance, force was produced with lower muscular activity reflecting increased efficiency. The resultant noise in the motor system associated with an internal focus inhibits movement economy and attempts at selective activation.

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... A summary of the aims, methods, conditions, measures, and main findings in the experiments reported in the 16 studies reviewed is provided in Table 4. An external focus of attention has produced lower EMG activity (peak EMG, average EMG, or integrated EMG) than an internal focus of attention in several studies (Vance et al., 2004;Marchant et al., 2008Marchant et al., , 2009Lohse et al., 2011;Lohse and Sherwood, 2012;Greig and Marchant, 2014;Marchant and Greig, 2017). An external focus has also shown superior performance over an internal focus for peak torque (Greig and Marchant, 2014), force production (Marchant et al., 2009;Halperin et al., 2016), reduced pre-movement time in early stages of learning an isometric force production task (Lohse, 2012), accuracy in a force production task (Lohse et al., 2011;Lohse and Sherwood, 2012), more repetitions before failure , and better movement kinematics for the snatch (Schutts et al., 2017). ...
... Frontiers in Sports and Active Living | www.frontiersin.org Marchant and Greig, 2017 To investigate the effect of internal focus instructions which emphasize specific muscular activity compared to external focus instructions which emphasize outcome on force and muscle activity during a knee extension task. ...
... The benefits of an external focus over an internal focus of attention in terms of reduced muscle activity may be explained by differences in the spread of activation between the two types of foci. In a knee extension task, Marchant and Greig (2017) reported that an internal focus of attention produced higher overall EMG, and that this was not specific to the muscles isolated in the task but that it reflected a spreading activation of increased muscle activity. The authors suggested that this pattern reflects than an external focus of attention results in increased muscular efficiency. ...
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The way an athlete focuses their attention when lifting a weight has the potential to influence strength development during training and performance outcomes during competition. The effects of attentional focus strategies during weightlifting tasks was investigated through a systematic review. Major databases (SportDISCUS, PsycINFO, Scopus) were searched using key terms relevant to attentional focus and weightlifting and reference lists of identified articles were also searched. Following screening, 16 articles were retained for analysis. The review showed that researchers have recruited experienced and novice weightlifters of both genders in their studies, although male experienced weightlifters are the most commonly studied demographic. Weightlifting tasks have varied from bench press, biceps curls, squats, and leg extensions with some studies using measures of force production against a force plate. The predominant manipulations have been between internal-associative and external-associative foci. An external attentional focus has shown to be beneficial in terms of movement economy as reflected in a variety of outcome measures. The results are interpreted within the framework provided by the Constrained Action Hypothesis and more generally the advantages of an external attentional focus for motor skill learning. An external focus of attention promotes automatic control of actions, thus preventing the motor system being constrained by conscious cognitive control. Implications for informing training programs for athletes and for advising athletes to maximize performance during competition are discussed.
... This study observed that adopting an external focus of attention resulted in a 9% higher peak force production. However, Marchant and Greig [14] did not replicate these findings, as in their study, there was no significant difference in isokinetic peak torque between internal and external focus. Therefore, while several studies explored the effect of different attentional focus strategies on muscular strength, there is still no consensus on this topic. ...
... Therefore, 28 full-text papers were read. Nineteen studies were excluded after reading the full texts, and a total of nine studies were included in the review [13][14][15][16][25][26][27][28][29]. There were 555 search results in the secondary searches, and one additional study was included in the review [30]. ...
... The data are presented as squares, which represent standardized mean differences (SMD) and whiskers, which are 95% confidence intervals (CIs). The diamond represents the pooled effect [13][14][15][16][25][26][27][28][29][30]. ...
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This review aimed to perform a meta-analysis examining the following: (a) acute effects of adopting an internal focus vs. external focus of attention on muscular strength; and (b) long-term effects of adopting an internal focus vs. external focus of attention during resistance training on gains in muscular strength. We searched through five databases to find eligible studies. Random-effects meta-analyses of standardized mean differences were conducted to analyze the data. Ten studies were included. In the meta-analysis for the acute effects, there was a significant positive effect of external focus on muscular strength (standardized mean difference: 0.34; 95% confidence interval: 0.22, 0.46). In the meta-analysis for the long-term effects, there was no significant difference between training with an internal focus and external focus on muscular strength gains (standardized mean difference: 0.32; 95% confidence interval: –0.08, 0.73). In the subgroup analysis for lower-body exercises, we found a significant positive effect of training with an external focus on muscular strength gains (standardized mean difference: 0.47; 95% confidence interval: 0.07, 0.87). In summary, our findings indicate an acute increase in muscular strength when utilizing an external focus of attention. When applied over the long-term, using an external focus of attention may also enhance resistance training-induced gains in lower-body muscular strength.
... These results were mostly in contrast to our initial hypothesis and may suggest that, for resistancetrained participants at least, adopting either an external or an internal focus of attention reduces the movement efficacy during submaximal bench press. Previous studies in various force production tasks have shown that external focus of attention led to decreased muscular activity and increased performance compared with an internal focus of attention or a control condition of no instruction (16,20,21,28). For example, an external focus of attention decreased EMG activity of the antagonist muscle and increased performance in an isometric plantar flexion of the ankle (16). ...
... In a test to determine the maximal amount of repetitions that could be performed in the Smith machine bench press, during free-weight bench press, and during free weight squat, an external focus of attention improved performance in all 3 tasks compared with an internal focus of attention (20). In a more recent study, an external focus of attention significantly reduced muscular activity during an isokinetic concentric leg extension exercise compared with an internal focus of attention (21), whereas force output remained the same between the 2 focus conditions. Most research in this area has demonstrated an external focus of attention to be superior to either an internal focus of attention or a control condition of no instructed focus in terms of performance and movement efficacy (18,40). ...
... In the aforementioned studies (16,17,20,21,28), conclusions have been drawn on the effects of different foci of attention on performance by measuring force production. This study, on the other hand, compared EMG amplitudes recorded during bench press using the same weight in all sets, but with different foci of attention. ...
Article
Kristiansen, M, Samani, A, Vuillerme, N, Madeleine, P, and Hansen, EA. External and internal focus of attention increases muscular activation during bench press in resistance-trained participants. J Strength Cond Res 32(9): 2442-2451, 2018-Research on the effects of instructed attentional focus during execution of strength training exercises is limited and has thus far only been performed on single-joint exercises. The aim of this study was to compare the effects of instructed internal (INT) and external (EXT) focus of attention with a baseline measurement of no instructed focus of attention (BASE) on the surface electromyographic (EMG) amplitude during a free-weight bench press exercise in resistance-trained participants. Twenty-one resistance-trained male participants performed bench press at 60% of their 3-repetition maximum, with BASE, EXT, and INT. The order of EXT and INT was randomized and counterbalanced. Electromyographic data were recorded from 13 muscles of the upper and lower body. Subsequently, mean and peak EMG amplitudes were computed. EXT and INT resulted in significantly increased mean EMG amplitude of 6 upper-body muscles as compared with BASE (p ≤ 0.05). In addition, EXT and INT also resulted in increased peak EMG amplitude of 3 upper-body muscles as compared with BASE (p ≤ 0.05). These results show that muscular activation is increased during bench press, when applying an instructed focus of attention compared with a baseline measurement with no focus instructions (BASE).
... For example, an internal vs external focus induced greater muscle excitation at light-to-moderate but not heavy loads, possibly pointing the load as possible factor influencing the difference in muscle excitation (Calatayud et al., 2016). In contrast, other studies reported no increases in muscle excitation both at moderate and high loads (Marchant & Greig, 2017;Paoli et al., 2019;Snyder & Fry, 2012), so that this aspect needs to be further investigated. It should be noted that the previous studies that have compared the internal vs external focus on dynamic exercises did not investigate separately the muscle excitation during the concentric or eccentric phase. ...
... Similar trend was also observed during push-up exercise (Calatayud et al., 2017). Internal vs external focus also elicited greater biceps brachii excitation when performing isokinetic biceps curl (Marchant et al., 2009) or greater quadriceps muscles excitation during isokinetic knee extension (Marchant & Greig, 2017). Although the complexity of the back-squat technique, the current results are in line with the overall literature, pointing out that the posterior hip muscles' activity increased with a specific internal focus. ...
... Similarly, resistance trained men increased the triceps brachii excitation at both 50% and 80% 1-RM following an internal focus in bench press, although no change in pectoralis major excitation neither at 50% nor at 80% 1-RM was visible when the internal focus was directed to the chest muscles (Paoli et al., 2019). Moreover, resistance trained men and women were able to enhance the quadriceps muscles excitation during maximal concentric isokinetic knee extension (Marchant & Greig, 2017). Conversely, young men selectively recruited pectoralis major up to 60% but not at 80% 1-RM during bench press exercise (Calatayud et al., 2016). ...
Article
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The present study investigated whether or not verbal instruction affects the electromyographic (EMG) amplitude of back-squat prime movers. Fifteen resistance-trained men performed back-squat at 50%1-RM and 80%1-RM and received external (EF) or internal focus (IF) on lower-limb posterior muscles. EMG amplitude of gluteus maximus, biceps femoris, gastrocnemius medialis, vastus lateralis and tibialis anterior was recorded during both concentric and eccentric phase. During the concentric phase, the gluteus maximus and biceps femoris EMG amplitude was greater in IF vs EF at 50% [effect size (ES): 0.63(95%CI 0.09/1.17) and 0.49(0.10/0.78) respectively] and 80% [ES: 1.30(0.29/2.21) and 0.59(0.08/1.10)]. The gastrocnemius medialis EMG amplitude was greater in IF vs EF during the eccentric phase at 50% [ES: 0.73(0.13/1.33)] and at 80% [ES: 0.72(0.10/1.34)]. Concomitantly, vastus lateralis EMG amplitude was lower at 50% [ES: −0.71(−1.38/-0.04)] and 80% [ES: −0.68(−1.33/-0.03)]. During the eccentric phase, the tibialis anterior EMG amplitude was greater in IF vs EF at 50% [ES: 0.90(0.12 to 1.68)] and 80% [ES: 0.74(0.13/1.45)]. Irrespective of the load, in the thigh muscles the internal focus promoted a different motor pattern, increasing the hip extensors and reducing the knee extensor excitation during the concentric phase. Concomitantly, both ankle muscles were more excited during the eccentric phase, possibly to increase the anterior-posterior balance control. The internal focus in back-squat seems to have phase-dependent effects, and it is visible at both moderate and high load.
... Furthermore, multiple subjects (n = 7) completed two to four repetitions lower than the established guideline of six for multiple attentional focus conditions. These findings are consistent with a previous study which found substantial individual variation during low-and high-load leg press (25 have previously demonstrated a potential ability to increase the involvement of synergistic musculature during high-intensity resistance training exercises as compared to those with fewer years of experience or whom were untrained (7,19). Therefore, the current study used 'years of resistance training experience' as a covariate to determine if RTF and motor unit excitation were influenced. ...
... However, training age did not provide any interaction effects, except a positive link between training age and triceps brachii motor unit excitation suggesting that individuals that had a longer training history elicited an increase in triceps' EMG amplitude. This finding supports previous studies, which hypothesized that increased EMG output is caused by beneficial neural adaptations associated with resistance training, such as improved synergistic stabilization and decreased antagonist co-activation (7,19). ...
Article
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Attentional focus strategies refer to the use of cues or other stimuli to enhance an individual’s concentration for the purpose of improving performance within a given task. PURPOSE: To examine the effects of an internal (INT), external proximal (EPr), and external distal (ED) method of attentional focus on motor unit excitation and repetitions-to-failure (RTF) during submaximal bench press performance. METHODS: Twenty-five recreationally-active males and females completed a one-repetition maximum (1RM) bench press test, followed by three days of submaximal testing at 85% 1RM to muscular failure. For each submaximal day, a specific attentional focus strategy was given by auditory cues (i.e., INT, EPr, ED) with the individual instructed to focus solely on the cue. Motor unit recruitment of the anterior deltoid, pectoralis major, and triceps brachii was measured, via electromyography (EMG), for each repetition for all interventions. RESULTS: Results indicated no differences for motor unit excitation (chest: p=0.59; triceps: p=0.50; deltoids: p=0.17) or RTF (p=0.89) among the three conditions. The INT cue, as compared to EPr and ED, elicited a ~7-10% average increase in pectoralis major motor unit excitation, despite an average of one less repetition. All effect sizes were deemed small or trivial, except for RTF between INT and ED which elicited a moderate effect size (ES=0.55). CONCLUSIONS: These findings support previous literature demonstrating increases in motor unit excitation with an internal attentional focus. However, this strategy may place a greater demand on the targeted musculature to complete a given task; thus, decreasing performance.
... However, some studies have used production measures, such as the neuromuscular level, through measures such as electromyography (EMG), to infer how movements were organized by the nervous system when individuals directed attention under external and internal focus conditions 12 . Specifically, it is expected that if an external focus results in greater automaticity than an internal focus, smaller EMG activity would be found 13,14 . That assumption is based on the proposition that an external focus promotes greater coherence between sensory input and motor output 13 . ...
... Specifically, it is expected that if an external focus results in greater automaticity than an internal focus, smaller EMG activity would be found 13,14 . That assumption is based on the proposition that an external focus promotes greater coherence between sensory input and motor output 13 . Greater coherence between sensory input and motor output generates a more discriminate motor unit recruitment, allowing the motor system an energy economy and less "noise" to perform movements 15 . ...
Article
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Aim: Attentional focus and demonstration have traditionally been investigated through outcome measures. Few studies have used other levels of analyses, such as the neuromuscular to explain the benefits of these two factors. The purpose of the present study was to examine whether there would be performance differences between external and internal focus of attention conditions and an online demonstration condition, and if these differences would be observed at a neuromuscular level through EMG analysis, in addition to traditional outcome measures. We hypothesized that under the demonstration condition participants would perform better than under external and internal focus conditions. We also hypothesized that demonstration condition would show smaller EMG activity than external and internal focus conditions. Furthermore, we hope to replicate the benefits of external focus in relation to internal focus, both in outcome and product measures. Methods: Six male participants performed a bilateral leg extension under internal focus of attention, external focus of attention and online demonstration conditions. Muscular contractions goal times were set for concentric muscle action (4 seconds) and eccentric muscle action (2 seconds). An electrogoniometer was used to record muscular activation (production measures), and temporal error was used to observe performance (outcome measures). Results: Results showed that online demonstration condition obtained better performance than external focus condition and a reduced muscular activation. However, differences between internal focus and the other experimental conditions were not found. Conclusion: These findings advance in the understanding mechanisms underpining the focus of attention, such as proposed by Constrained Action Hypothesis.
... The addition of visual feedback with verbal encour- agement has been shown to generate greater quadriceps and hamstring force and PT during isokinetic knee testing (10), and greater PT during isometric knee flexion (38) than verbal encouragement alone. Attentional focusing instructions, rather than instructions based on rate and magnitude, have also been shown to influence force production and muscle activity (26,27). During isometric leg extension contractions, internal (muscle-specific) focusing instructions produced greater quadriceps activity than external (outcome-specific) focusing instructions with no difference in torque produc- tion, indicating that external focusing instructions may be more efficient (less muscle activity to produce the same force) than internal focusing instructions (26). ...
... Attentional focusing instructions, rather than instructions based on rate and magnitude, have also been shown to influence force production and muscle activity (26,27). During isometric leg extension contractions, internal (muscle-specific) focusing instructions produced greater quadriceps activity than external (outcome-specific) focusing instructions with no difference in torque produc- tion, indicating that external focusing instructions may be more efficient (less muscle activity to produce the same force) than internal focusing instructions (26). Similarly, external focusing instructions resulted in significantly greater force production and lower muscle activity of the elbow flexors during isokinetic contractions (27). ...
Article
Rendos, NK, Harriell, K, Qazi, S, Regis, RC, Alipio, TC, and Signorile, JF. Variations in verbal encouragement modify isokinetic performance. J Strength Cond Res XX(X): 000-000, 2018-Verbal instruction and encouragement are common in exercise testing; however, the verbiage used during exercise testing is rarely controlled despite the likelihood it may affect the participant's performance. Although variations in verbal cuing based on rate and intensity have been examined during isometric contractions, they have not been examined during isokinetic testing, which is a standardized assessment of muscle performance in athletic, rehabilitation, and research settings. This study examined the effects of 4 variations in verbal encouragement during isokinetic knee flex-ion and extension exercises. Twenty-three healthy participants (aged 19-34 years) completed 4 isokinetic testing sessions on a Biodex isokinetic dynamometer. Each session consisted of 5, 10, and 15 repetitions at 1.05 rad$s 21
... Additionally, Marchant et al. (2009) found that an external focus resulted in greater force production and lower peak and mean EMG excitation during an isokinetic bicep curl. Similarly, an external focus yielded significantly lower integrated EMG excitation during an isokinetic leg extension (Marchant & Greig, 2017). Vance et al. (2004), in addition to more recent studies, concluded that focusing externally results in more efficient muscular recruitment and reduces "noise" in the motor system compared to directing attention internally (Marchant & Greig, 2017;Marchant et al., 2009;Zachary et al., 2005). ...
... Similarly, an external focus yielded significantly lower integrated EMG excitation during an isokinetic leg extension (Marchant & Greig, 2017). Vance et al. (2004), in addition to more recent studies, concluded that focusing externally results in more efficient muscular recruitment and reduces "noise" in the motor system compared to directing attention internally (Marchant & Greig, 2017;Marchant et al., 2009;Zachary et al., 2005). ...
Article
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Subtle instructional changes that direct attentional focus can lead to changes in performance, potentially hindering a fitness assessment. An external attentional focus has been found to improve motor performance, however less is known about instructional effects on performance and the physiological response during an isometric endurance test. To better understand how attentional focus effects endurance fitness tests, two experiments were conducted. Experiment 1 showed that an external focus instruction (68.41 sec, SD = 34.20) led to significantly higher endurance performance compared to an internal instruction (60.22 sec, SD = 34.54). Experiment 2 revealed that heart rate during the internal condition (M = 117.51 bpm, SD = 14.19) was higher compared to the external (M = 114.17 bmp, SD = 13.19) and control (M = 115.40 bpm, SD = 16.85). Additionally, performance was greater during external instructions (M = 107.01 sec, SD = 46.35) compared to internal (M = 95.25 sec, SD = 38.19).
... However, external focus of attention does result in decreased motor cortex inhibition, agonist EMG activity, and antagonist coactivation, suggesting stronger muscle recruitment patterns. [190][191][192][193] Interestingly, a shift in EMG median frequency may also indicate recruitment of larger motor units when adopting an internal focus of attention, 191 yet an external focus of attention generally leads to greater maximal force production in healthy individuals. [192][193][194][195] Extending these findings to muscle inhibition, external focus of attention is likely most appropriate as it can increase quadriceps voluntary activation and diminish antagonist coactivation (ie, hamstrings-to-quadriceps) and, thus, facilitate isolated quadriceps activation. ...
... [190][191][192][193] Interestingly, a shift in EMG median frequency may also indicate recruitment of larger motor units when adopting an internal focus of attention, 191 yet an external focus of attention generally leads to greater maximal force production in healthy individuals. [192][193][194][195] Extending these findings to muscle inhibition, external focus of attention is likely most appropriate as it can increase quadriceps voluntary activation and diminish antagonist coactivation (ie, hamstrings-to-quadriceps) and, thus, facilitate isolated quadriceps activation. ...
Article
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Context: Arthrogenic muscle inhibition (AMI) impedes the recovery of muscle function following joint injury, and in a broader sense, acts as a limiting factor in rehabilitation if left untreated. Despite a call to treat the underlying pathophysiology of muscle dysfunction more than three decades ago, the continued widespread observations of post-traumatic muscular impairments are concerning, and suggest that interventions for AMI are not being successfully integrated into clinical practice. Objectives: To highlight the clinical relevance of AMI, provide updated evidence for the use of clinically accessible therapeutic adjuncts to treat AMI, and discuss the known or theoretical mechanisms for these interventions. Evidence acquisition: PubMed and Web of Science electronic databases were searched for articles that investigated the effectiveness or efficacy of interventions to treat outcomes relevant to AMI. Evidence synthesis: 122 articles that investigated an intervention used to treat AMI among individuals with pathology or simulated pathology were retrieved from 1986 to 2021. Additional articles among uninjured individuals were considered when discussing mechanisms of effect. Conclusion: AMI contributes to the characteristic muscular impairments observed in patients recovering from joint injuries. If left unresolved, AMI impedes short-term recovery and threatens patients' long-term joint health and well-being. Growing evidence supports the use of neuromodulatory strategies to facilitate muscle recovery over the course of rehabilitation. Interventions should be individualized to meet the needs of the patient through shared clinician-patient decision-making. At a minimum, we propose to keep the treatment approach simple by attempting to resolve inflammation, pain, and effusion early following injury.
... Consequently, this interruption leads to lower movement performance (Wulf, 2013). To that end, electromyography (EMG) analysis found that participants instructed with an internal attentional focus showed greater muscular activity than those instructed with an external attentional focus (Lohse et al., 2010;Marchant et al., 2009;Marchant & Greig, 2017). A few studies hypothesize that an internal focus of attention may direct attention towards the self. ...
... For the first quantitative analysis (original classifications of instructions), an additional 22 studies were excluded (n = 61). These studies were excluded because (1) key statistical values were missing (Ashraf et al., 2012;Hosseiny et al., 2014;Kearney, 2015;Khalaf, 2014;van Abswoude et al., 2018); (2) more than one performance parameter was used and no ranking was possible (Greig & Marchant, 2014;Halperin et al., 2017;Makaruk et al., 2015;Marchant et al., 2009;Marchant & Greig, 2017;Wulf et al., 2004;Wulf, Töllner, et al., 2007); or (3) a between-subject design was used (Becker & Smith, 2015;Bell & Hardy, 2009;Ehrlenspiel et al., 2004;Harris et al., 2019;Land et al., 2013;Makaruk et al., 2019;Marchant et al., 2007;Pinto et al., 2020;Porter, Ostrowski, et al., 2010). Moreover, the third part of Marchant et al. (2011) study was excluded because the same participants were investigated as in study part two. ...
Article
Directing the attentional focus towards intended movement effects could enhance individual performance. This meta-analysis examines the immediate effects of an instructed external (proximal/distal) and internal attentional focus on an experimental group and a control group on their performance. A systematic review was done following the PRISMA guidelines. A total of 3833 reports were scanned. Of these, 83 were included in the systematic review, and 61 studies were included into the meta-analysis. The meta-analysis was additionally split into the original categories, which included the instructions as mentioned in the paper, and the adapted classifications, for which the instructions were reclassified based on the definition by [Wulf, G. (2013). Attentional focus and motor learning: A review of 15 years. International Review of sport and Exercise psychology, 6(1), 77–104. doii:10.1080/1750984X.2012.723728 and McNevin, N. H., Shea, C. H., & Wulf, G. (2003). Increasing the distance of an external focus of attention enhances learning. Psychological Research, 67(1), 22–29. doii:10.1007/s00426-002-0093-6]. In line with the constrained-action hypothesis, an external attentional focus instruction enhanced the immediate performance compared to an internal attentional focus instruction (SMDadapted = 0.24) and the control group (SMDadapted SMD = 0.31). Also, consistent with the constrained-action hypothesis, distal external attentional focus instructions showed performance-enhancing effects compared to proximal external attentional focus instructions (SMDadapted = 0.23). However, most comparisons showed moderate to substantial heterogeneity and wide prediction intervals. Therefore, the results cannot be generalized for all tasks and skill levels.
... coordination, while attention directed to the results of the movement promotes automated processing. This has been supported by studies using electromyography (EMG), showing lesser neuromuscular activation in an external focus condition (i.e., less control necessary for enhanced performance) (Marchant & Greig, 2017) with poorer performance when internal focus is adopted relative to external focus (Lohse, Sherwood, & Healy, 2010;Marchant, Greig, & Scott, 2009;Wulf, Dufek, Lozano, & Pettigrew, 2010;Zachry et al., 2005). Studies in movement coordination have also demonstrated automaticity, with an external focus showing greater mean power frequency (MPF) relative to internal focus for balance, which is indicative of well-learned coordination (McNevin et al., 2003;Wulf, McNevin, et al., 2001). ...
... For each angular velocity and contraction mode, the participants were instructed to provide 3 maximal contractions. A 60 s rest period was provided between each angular velocity (Lee et al., 2017), and no performance feedback or instructions were provided during the experimental procedures due to reported effects on isokinetic torque (Campenella, Mattacola, & Kimura, 2000) and due to equivocal results when giving internal and external instructions during isokinetic strength assessments (Marchant & Greig, 2017). The range of motion (ROM) of the knee joint was set at 25e90 (0 ¼ full extension) with the anatomical reference set at 90 . ...
Article
Objectives: To compare traditional and angle-specific isokinetic strength of eccentric knee flexors and concentric knee extensors in female senior professional and youth soccer players. Design: Cross-sectional study design. Setting: University's Laboratory. Participants: A total of 34 players (17 seniors [age 25.31 ± 4.51 years; height 167.89 ± 7.04 cm; mass 63.12 ± 7.79 kg] and 17 youths [16.91 ± 1.16 years; height 165.92 ± 4.42 cm; mass 60.07 ± 4.48 kg]) from the Women's Super League 1 completed strength assessments at 180, 270 and 60°∙s-1. Main outcome measures: Peak torque (PT), dynamic control ratio (DCR), angle of peak torque (APT), functional range (FR), angle-specific torque (AST) and angle-specific DCR (DCRAST) were compared between age groups. Results: The PT (P = 0.016) AST (P = 0.041) were significantly higher in seniors compared to youths; however APT (P = 0.141), DCR (P = 0.524) FR (P = 0.821) and DCRAST (P = 0.053) were not significant between playing age. Conclusion: The use of absolute and angle-specific strength measures were able to distinguish between female playing ages, whereas DCR and DCRAST was unable to identify differences. The PT and AST metrics may be the most useful metrics to help identify and inform training needs, particularly in youths.
... between the external and internal focus condition in the partial LESS items, the effect of external focus in the overall scores suggests that there was a negative effect of internal focus in the other LESS items that were not specified in the instructional cues (eg, overall impression of landing quality, trunk motion, and hip motion). An explanation for this result may be derived from the findings by Marchant and Greig, 51 showing that the increased EMG activity of the leg muscles using an internal focus was not selective (ie, not only in the targeted muscle activity) but instead was the overall activity of the entire lower leg EMG activity. Marchant and Greig 51 concluded that internal focus exhibited a "spreading activation effect." ...
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Contexts: Directing an individual's attention to the effect of the movements (external focus) has been shown to improve performance than directing attention to body movements (internal focus). However, the effect of attentional focus instructions specific to movement quality has not been investigated thoroughly. Objective: To compare the effects of internal and external focus instructions specific to body movements. Design: Mixed design, 2 (sex) × 2 (instructions). Settings: Laboratory setting. Participants: A total of 40 participants (males, n = 20; mean [SD]; age = 22.0 [2.19] y; height = 179.33 [5.90] cm; mass = 77.7 [13.04] kg; females, n = 20; age = 22.0 [3.87] y; height = 164.84 [5.80] cm; mass = 71.48 [20.66] kg) were recruited. Intervention: Participants completed 2 consecutive jumps (ie, a forward jump from a height and then a maximal vertical jump) with internal focus and external focus instructions. External focus was elicited by placing pieces of tape on the participants' legs. Main outcome measures: Landing quality was measured by the Landing Error Scoring System to assess movement quality, and the vertical jump height was measured by Vertec. Results: The performance results showed that the external focus condition resulted in superior vertical jump height compared with the internal focus condition (P < .05). Although landing quality did not show significant differences between 2 conditions, the effect size (η2 = .09) indicated that landing quality was better when participants adopted an external, rather than an internal focus of attention (P = .07). Conclusions: The body-oriented instructions can be provided externally by adding artificial external cues and directing attention to them. Importantly, the findings were evident in a qualitative assessment that can be adopted by practitioners. The results suggest that practitioners should adopt an external focus cue for performance and also consider using an external focus for movement quality.
... It is a also a basic and simple movement to do for beginners [29]. • Knee Extension: this exercise is able to be done using only the muscles of the quadriceps, making it possible to isolate the activation effect on associated muscles and focus on the selected muscle [30]. • Jump: This exercise combines the characteristics of the squat and sums movement up, therefore the analysis is more exhausting. ...
Article
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Electromyography (EMG) devices are well-suited for measuring the behaviour of muscles during an exercise or a task, and are widely used in many different research areas. Their disadvantage is that commercial systems are expensive. We designed a low-cost EMG system with enough accuracy and reliability to be used in a wide range of possible ways. The present article focuses on the validation of the low-cost system we designed, which is compared with a commercially available, accurate device. The evaluation was done by means of a set of experiments, in which volunteers performed isometric and dynamic exercises while EMG signals from the rectus femoris muscle were registered by both the proposed low-cost system and a commercial system simultaneously. Analysis and assessment of three indicators to estimate the similarity between both signals were developed. These indicated a very good result, with spearman’s correlation averaging above 0.60, the energy ratio close to the 80% and the linear correlation coefficient approximating 100%. The agreement between both systems (custom and commercial) is excellent, although there are also some limitations, such as the delay of the signal (<1 s) and noise due to the hardware and assembly in the proposed system.
... between the external and internal focus condition in the partial LESS items, the effect of external focus in the overall scores suggests that there was a negative effect of internal focus in the other LESS items that were not specified in the instructional cues (eg, overall impression of landing quality, trunk motion, and hip motion). An explanation for this result may be derived from the findings by Marchant and Greig, 51 showing that the increased EMG activity of the leg muscles using an internal focus was not selective (ie, not only in the targeted muscle activity) but instead was the overall activity of the entire lower leg EMG activity. Marchant and Greig 51 concluded that internal focus exhibited a "spreading activation effect." ...
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Contexts: Directing an individual’s attention to the effect of the movements (external focus) has been shown to improve performance than directing attention to body movements (internal focus). However, the effect of attentional focus instructions specific to movement quality has not been investigated thoroughly. Objective: To compare the effects of internal and external focus instructions specific to body movements. Design: Mixed design, 2 (sex) × 2 (instructions). Settings: Laboratory setting. Participants: A total of 40 participants (males, n = 20; mean [SD]; age = 22.0 [2.19] y; height = 179.33 [5.90] cm; mass = 77.7 [13.04] kg; females, n = 20; age = 22.0 [3.87] y; height = 164.84 [5.80] cm; mass = 71.48 [20.66] kg) were recruited. Intervention: Participants completed 2 consecutive jumps (ie, a forward jump from a height and then a maximal vertical jump) with internal focus and external focus instructions. External focus was elicited by placing pieces of tape on the participants’ legs. Main Outcome measures: Landing quality was measured by the Landing Error Scoring System to assess movement quality, and the vertical jump height was measured by Vertec. Results: The performance results showed that the external focus condition resulted in superior vertical jump height compared with the internal focus condition (P < .05). Although landing quality did not show significant differences between 2 conditions, the effect size (η2 = .09) indicated that landing quality was better when participants adopted an external, rather than an internal focus of attention (P = .07). Conclusions: The body-oriented instructions can be provided externally by adding artificial external cues and directing attention to them. Importantly, the findings were evident in a qualitative assessment that can be adopted by practitioners. The results suggest that practitioners should adopt an external focus cue for performance and also consider using an external focus for movement quality.
... Adopting an external FOA also forms a key part of the optimizing performance through intrinsic motivation and attention for learning theory of motor learning (Wulf & Lewthwaite, 2016), which also includes methods of enhancing the student's expectancies for future performances and promoting learner autonomy. Furthermore, motor performance research has found that an internal focus may cause a physiological change in the motor system through increased electromyographic (EMG) muscle activation, indicating decreased efficiency of muscle use (Marchant & Greig, 2017;Neumann, 2019;Neumann & Brown, 2013;Vance et al., 2004). Such an effect in musicians may have implications for efficient use of the body in performance, which could be important in the prevention of overuse injuries. ...
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The constrained action hypothesis states that focusing attention on action outcomes rather than body movement improves motor performance. Dexterity of motor control is key to successful music performance, making this a highly relevant topic to music education. We investigated effects of focus of attention (FOA) on motor skill performance and EMG muscle activity in a violin bowing task among experienced and novice upper strings players. Following a pedagogically informed exercise, participants attempted to produce single oscillations of the string at a time under three FOA: internal (on arm movement), external (on sound produced), and somatic (on string resistance). Experienced players’ number of bow slips was significantly reduced under somatic focus relative to internal, although number of successful oscillations was not affected. Triceps electromyographic activity was also significantly lower in somatic compared to internal foci for both expertise groups, consistent with physiological understandings of FOA effects. Participants’ reported thoughts during the experiment provided insight into whether aspects of constrained action may be evident in performers’ conscious thinking. These results provide novel support for the constrained action hypothesis in violin bow control, suggesting a somatic FOA as a promising performance-enhancing strategy for bowed string technique.
... In line with previous research that an external focus promotes more efficient muscle use (e.g. Marchant & Greig, 2017;Neumann & Brown, 2013;Vance et al., 2004), we found significantly reduced muscle activity in the deltoid muscle (shoulder) under somatic focus (a type of external focus) compared to internal. This, to our knowledge, is novel evidence of this physiological effect in a music task. ...
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Violin bowing is a specialised sound-producing action, which may be affected by psychological performance techniques. In sport, attentional focus impacts motor performance, but limited evidence for this exists in music. We investigated the effects of attentional focus on acoustical, physiological, and physical parameters of violin bowing in experienced and novice violinists. Attentional focus significantly affected spectral centroid, bow contact point consistency, shoulder muscle activity, and novices’ violin sway. Performance was most improved when focusing on tactile sensations through the bow (somatic focus), compared to sound (external focus) or arm movement (internal focus). Implications for motor performance theory and pedagogy are discussed.
... Such sentiments do not preclude one from being able to learn how to effectively utilize an internal focus of attention. That is, such a phenomenon may be related to the subjects' untrained statuses, as individuals with RT experience have been shown to be able to increase quadriceps EMG amplitude when directed to focus on the thigh musculature during knee extension exercise (Marchant & Greig, 2017), and recent evidence suggests that training statusdependent control may indeed be muscle-specific (Calatayud et al., 2016). If true, this would suggest that trained individuals may be able to enhance quadriceps hypertrophy by adopting an internal focus during lower body RT. ...
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The purpose of this study was to investigate the effects of using an internal versus external focus of attention during resistance training on muscular adaptations. Thirty untrained college-aged men were randomly assigned to an internal focus group (INTERNAL) that focused on contracting the target muscle during training (n = 15) or an external focus group (EXTERNAL) that focused on the outcome of the lift (n = 15). Training for both routines consisted of 3 weekly sessions performed on non-consecutive days for 8 weeks. Subjects performed 4 sets of 8–12 repetitions per exercise. Changes in strength were assessed by six repetition maximum in the biceps curl and isometric maximal voluntary contraction in knee extension and elbow flexion. Changes in muscle thickness for the elbow flexors and quadriceps were assessed by ultrasound. Results show significantly greater increases in elbow flexor thickness in INTERNAL versus EXTERNAL (12.4% vs. 6.9%, respectively); similar changes were noted in quadriceps thickness. Isometric elbow flexion strength was greater for INTERNAL while isometric knee extension strength was greater for EXTERNAL, although neither reached statistical significance. The findings lend support to the use of a mind–muscle connection to enhance muscle hypertrophy.
... Continued and isokinetic contractions of the elbow flexors, an external focus of attention increases force~8% compared to an internal focus of attention (170,263) and~3% compared to a control condition (170,263). However, during isokinetic contractions of the knee extensors, attentional focusing does not influence peak torque (262). Imagery. ...
Article
Muscle strength - the maximal force generating capacity of a muscle or group of muscles - is regularly assessed in physiological experiments and clinical trials. An understanding of the expected variation in strength and the factors that contribute to this variation is important when designing experiments, describing methodologies, interpreting results, and attempting to replicate methods of others and reproduce their findings. In this review (Cores of Reproducibility in Physiology), we report on the intra- and inter-rater reliability of tests of upper- and lower-limb muscle strength and voluntary activation in humans. Isometric, isokinetic, and isoinertial strength exhibit good intra-rater reliability in most samples (correlation coefficients ≥ 0.90). However, some tests of isoinertial strength exhibit systematic bias that is not resolved by familiarization. With the exception of grip strength, few attempts have been made to examine inter-rater reliability of tests of muscle strength. The acute factors most likely to affect muscle strength and serve as a source of its variation from trial-to-trial or day-to-day include: attentional focus, breathing technique, remote muscle contractions, rest periods, temperature (core, muscle), time of day, visual feedback, body and limb posture, body stabilization, acute caffeine consumption, dehydration, pain, fatigue from preceding exercise, and static stretching >60 seconds. Voluntary activation - the nervous system's ability to drive a muscle to create its maximal force - exhibits good intra-rater reliability when examined with twitch interpolation (correlation coefficients > 0.80). However, inter-rater reliability has not been formally examined. Methodological factors most likely to influence voluntary activation are: myograph compliance and sensitivity; stimulation location, intensity, and inadvertent stimulation of antagonists; joint angle (muscle length); and the resting twitch.
Chapter
Attention focus plays an essential role in promoting motor performance and motor learning. There are two types of attention focus: internal focus and external focus. Internal focus refers to direct attention inside the body while external focus refers to direct attention outside the body. Several studies have reported that external focus positively affects motor performance and motor learning by promoting automatic control. The mechanisms of attention focus have been examined using electromyography (EMG), electroencephalography (EEG), and functional magnetic resonance imaging (fMRI). During rehabilitation, therapists promote patients’ movement acquisition and motor learning. This chapter reviews the application of attention focus in rehabilitation to promote motor performance and motor learning in patients.
Article
The purpose of this study was to assess whether dynamic torque ratios (DCR) from isokinetic strength assessments of eccentric knee flexors (eccKF) and concentric knee extensors (conKE) display differences when stratified into specific angle-specific DCR (DCRAST) groups. Fifty-two professional female soccer players (age 21.30 ± 4.44 years; height 166.56 ± 5.17 cm; mass 61.55 ± 5.73 kg) from the English Women's Super League completed strength assessments of both lower limbs on an isokinetic dynamometer at 60°∙s-1. Angle-specific torque (AST) were used to calculate DCRAST to create sub-groups using clustering algorithms. The results identified for the dominant side that the Medium DCRAST group elicited significantly higher conKE AST when compared to Low and High DCRAST groups at increased knee extension (P ≤ 0.05). For the non-dominant side, the High DCRAST group had significantly higher and lower eccKF and conKE AST compared to the Low DCRAST group at increased knee extension (P ≤ 0.05). This study highlights that the inclusion of AST data may subsequently help practitioners to prescribe exercise that promotes strength increases at targeted joint angles. In turn, these approaches can be used to help reduce injury risk, identify rehabilitation responses and help inform return to play.
Conference Paper
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Functional Electrical Stimulation (FES) activates nerves and muscles that have been ravished and rendered paralysed by disease. As such, it is advantageous to study joint torques that arise due to electrical stimulation of muscle, to measure fatigue in an indirect, minimally-invasive way. Dynamometry is one way in which this can be achieved. In this paper, torque data is presented from an FES experiment on quadriceps, using isometric dynamometry to measure torque. A library of fatigue metrics to quantify these data are put forward. These metrics include; start and end torque peaks, percentage changes in torque over time, and maximum and minimum torque period algorithms (MTPA 1 and 2), and associated torque-time plots. It is illustrated, by example, how this novel library of metrics can model fatigue over time. Furthermore, these methods are critiqued by a qualitative assessment and compared against one another for their utility in modelling fatigue. Linear trendlines with coefficients of correlation (R ²) and qualitative descriptions of data are used to achieve this. We find that although arduous, individual peak plots yield the most relevant values upon which fatigue can be assessed. Methods to calculate peaks in data have less of a utility, offset by an order of magnitude of ~10¹ in comparison with theoretically expected peak numbers. In light of this, we suggest that future methods would be well-inclined to investigate optimized form of peak analysis.
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Numerous studies have demonstrated that using verbal instructions to direct a performers' attention externally significantly enhances motor skill performance. Limited research has also demonstrated that increasing the distance of an external focus relative to the body magnifies the effect of an external focus of attention. The purpose of this study was to investigate the effect of increasing the distance of an external focus of attention on standing long jump performance in a highly trained population. Using a counterbalanced, within-participant design, current collegiate male athletes (n = 38, age = 20.7 yrs, SD = 2.2 yrs) performed two standing long jumps following four different sets of verbal instructions. Subjects completed all eight trials in one testing session, which lasted approximately 20 minutes. One set of instructions was designed to focus attention internally toward the movements of the body (INT); a second set of instructions focused attention externally near the body (EXN); another set of instructions directed attention externally to a target farther from the body (EXF); the last set of instructions served as a control condition (CON) and encouraged the athlete to use his "normal" focus while jumping. Results indicated that the EXN and EXF conditions elicited jump distances that were significantly greater than the INT and CON conditions. In addition, the participants jumped significantly farther in the EXF condition than the EXN condition. These findings suggest that increasing the distance of an external focus of attention relative to the body, immediately improved standing long jump performance in a highly trained population.
Article
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A performer’s focus of attention has been shown to influence motor performance and learning in a variety of motor skills. The purpose of the current study was to examine the effects of an external and internal focus of attention on discus throwing. Participants (N=20; mean age: 22 years, SD: 1.58) were recruited from an undergraduate male student population that had limited experience with the task. Using a within-participants design, all participants completed five maximum effort trials under each attentional focus condition (external and internal). The results of a repeated-measures ANCOVA revealed that participants had a significantly more effective performance in external focus of attention condition compared with the internal attentional focus. These findings are in line with the previous studies showing enhanced motor performance as a result of using external versus internal focus of attention. Therefore, it is suggested that coaches and practitioners give instructions that promote an external focus of attention.
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The influence of internal (movement focus) and external (outcome focus) attentional-focusing instructions on muscular endurance were investigated using three exercise protocols with experienced exercisers. Twenty-three participants completed a maximal repetition, assisted bench-press test on a Smith's machine. An external focus of attention resulted in significant (p < .05) improvements in performance compared to the internal focus of attention, but not the control condition. Seventeen participants completed repetitions to failure at 75% 1-RM on free bench-press and squat exercises. In both tasks, externally focused instructions resulted in significantly greater repetitions to failure than control and internal focus conditions (p < .05). These results support previous research showing beneficial effects of externally focused instructions on movement efficiency.
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Appropriate verbal instruction is critical to effective guidance of movements. Internal (movement focus) and external (outcome focus) attentional focusing instructions have been shown to influence movement kinetics and muscular activity; this study investigated their effects during a force production task. Twenty-five participants (mean age of 22.72 +/- 1.88 years) completed 10 repetitions of single-arm elbow flexions on an isokinetic dynamometer while electromyographical activity of the biceps brachii and net joint elbow flexor torque were measured. Three trials were completed: a control trial to attain maximum voluntary contraction (MVC) data, followed by counterbalanced trials internal and external attentional focus conditions. The external focus exhibited a significantly (p < 0.05) higher peak net joint torque (102.10 +/- 2.42%MVC) than the internal condition (95.33 +/- 2.08%MVC) and also a greater integral of the torque-time curve (99.90 +/- 2.91%MVC) than the internal condition (93.80 +/- 2.71%MVC). In addition, the external focus resulted in lower peak electromyography (134.43 +/- 16.83%MVC) response when compared with the internal focus condition (155.23 +/- 22.54%MVC) as well as lower mean integrated electromyography (127.55 +/- 12.24%MVC) than the internal condition (154.99 +/- 19.44%MVC). Results indicate that an external attentional focus results in significantly greater force production and lower muscular activity during isokinetic elbow flexions when compared with an internal focus. When instructing clients during maximal force production tasks, practitioners should tailor their instructions to emphasize an external focus of attention. Specifically, attention should be directed onto the movement of the object being moved and away from the specific bodily movements involved in the action.
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Motor control and learning possibilities of scapular muscles are of clinical interest for restoring scapular muscle balance in patients with neck and shoulder disorders. The aim of the study was to investigate whether selective voluntary activation of intra-muscular parts within the serratus anterior can be learned with electromyographical (EMG) biofeedback, and whether the lower serratus anterior and the lower trapezius muscle comprise the lower scapula rotation force couple by synergistic activation. Nine healthy males practiced selective activation of intra-muscular parts within the serratus anterior with visual EMG biofeedback, while the activity of four parts of the serratus anterior and four parts of the trapezius muscle was recorded. One subject was able to selectively activate both the upper and the lower serratus anterior respectively. Moreover, three subjects managed to selectively activate the lower serratus anterior, and two subjects learned to selectively activate the upper serratus anterior. During selective activation of the lower serratus anterior, the activity of this muscle part was 14.4+/-10.3 times higher than the upper serratus anterior activity (P<0.05). The corresponding ratio for selective upper serratus vs. lower serratus anterior activity was 6.4+/-1.7 (P<0.05). Moreover, selective activation of the lower parts of the serratus anterior evoked 7.7+/-8.5 times higher synergistic activity of the lower trapezius compared with the upper trapezius (P<0.05). The learning of complete selective activation of both the lower and the upper serratus anterior of one subject, and selective activation of either the upper or lower serratus anterior by five subjects designates the promising clinical application of EMG biofeedback for restoring scapular muscle balance. The synergistic activation between the lower serratus anterior and the lower trapezius muscle was observed in only a few subjects, and future studies including more subjects are required before conclusions of a lower scapula rotation couple can be drawn.
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The present experiment was designed to test the predictions of the constrained-action hypothesis. This hypothesis proposes that when performers utilize an internal focus of attention (focus on their movements) they may actually constrain or interfere with automatic control processes that would normally regulate the movement, whereas an external focus of attention (focus on the movement effect) allows the motor system to more naturally self-organize. To test this hypothesis, a dynamic balance task (stabilometer) was used with participants instructed to adopt either an internal or external focus of attention. Consistent with earlier experiments, the external focus group produced generally smaller balance errors than did the internal focus group and responded at a higher frequency indicating higher confluence between voluntary and reflexive mechanisms. In addition, probe reaction times (RTs) were taken as a measure of the attention demands required under the two attentional focus conditions. Consistent with the hypothesis, the external focus participants demonstrated lower probe RTs than did the internal focus participants, indicating a higher degree of automaticity and less conscious interference in the control processes associated with the balance task.
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Functional training is considered to be training that attempts to mimic the specific physiological demands of real-life activities. Most approaches to functional training, though, omit important factors that contribute to physiological and neuromotor adaptations. Cognitive factors related to sports influence physiological performance, and subsequently, physiological and neuromotor adaptations. We present a rationale and a theoretical framework by which to create effective functional training methods that incorporate cognitive factors. This framework draws upon recent developments and strong empirical evidence in the areas of dynamic systems theory, perceptual skills training, and motor learning/control. Emphasized within rigorous physical training are practice-related techniques and motor-learning strategies. In particular, mental effort, attention, and intention manipulated in a discovery-learning paradigm provide a framework for functional strength and power training. This framework is suggested to help maximize sport-specific physiological adaptations, and subsequently, sports performance.
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Previous studies (e.g., Wulf, Höss, & Prinz, 1998) have shown that motor learning can be enhanced by directing performers' attention to the effects of their movements ("external focus"), rather than to the body movements producing the effect ("internal focus"). The purpose of the present study was to test the hypothesis that increasing the distance between the body and the action effects might further enhance the learning advantages associated with an external focus of attention. The distance of the external effect was manipulated by instructing three groups of participants learning to balance on a stabilometer to focus on markers attached to the platform located at different distances from their feet. Specifically, two groups were to focus on distant markers on the outside ("far-outside") or inside ("far-inside") of the platform, respectively, whereas another group was instructed to focus on markers close to their feet ("near"). In a retention test administered after two days of practice, all three external-focus groups showed generally more effective balance learning than an internal-focus control group. In addition, the far-outside and far-inside groups demonstrated similar performances, and both were more effective than the near group. Furthermore, the far-outside and far-inside groups showed higher-frequency movement adjustments than the near group. These results suggest that focusing on more distant effects results in enhanced learning by promoting the utilization of more natural control mechanisms. The findings are in line with a "constrained action" hypothesis that accounts for the relatively poorer learning associated with an attentional focus directed towards effects in close proximity to the body, or towards the body itself.
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Minimising the likelihood of injury to the anterior cruciate ligament (ACL) during abrupt deceleration requires proper synchrony of the quadriceps and hamstring muscles. However, it is not known whether simple verbal instructions can alter landing muscle activity to protect the knee. To assess the efficacy of verbal instructions to alter landing muscle activity. Twenty four athletes landed abruptly in single limb stance. Sagittal plane motion was recorded with an optoelectric device, and ground reaction force and surface electromyographic data were recorded for the rectus femoris, vastus lateralis, biceps femoris, and semimembranosus muscles. Subjects performed 10 landings per condition: normal landing (N); repeat normal landing (R); landing after instruction to increase knee flexion (K); and landing after instruction to recruit hamstring muscles earlier (M). Muscle bursts immediately before landing were analysed relative to initial foot-ground contact (IC). The K condition resulted in significantly (p</=0.05) greater knee flexion at IC compared with the other conditions. The M condition did not result in earlier hamstring muscle activity, but instead caused significantly (p</=0.05) earlier rectus femoris onset relative to IC, with a similar trend for the vastus lateralis. As these muscles are ACL antagonists, earlier onset times would be detrimental to the ACL. Subjects successfully increased knee flexion during landing following the K condition instruction. However, further research is warranted to establish the efficacy of more extensive lower limb muscle retraining programmes to ensure landings that decrease susceptibility to ACL injury.
Article
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In previous studies of attentional focus effects, investigators have measured performance outcome. Here, however, the authors used electromyography (EMG) to determine whether difference between external and internal foci would also be manifested at the neuromuscular level. In 2 experiments, participants (N=11, Experiment 1; N=12, Experiment 2) performed biceps curls while focusing on the movements of the curl bar (external focus) or on their arms (internal focus). In Experiment 1, movements were performed faster under external than under internal focus conditions. Also, integrated EMG (iEMG) activity was reduced when performers adopted an external focus. In Experiment 2, movement time was controlled through the use of a metronome, and iEMG activity was again reduced under external focus conditions. Those findings are in line with the constrained action hypothesis (G. Wulf, N. McNevin, & C. H. Shea, 2001), according to which an external focus promotes the use of more automatic control processes.
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A repeated-measures, counterbalanced design. To test whether subjects could learn and retain the ability to alter the relative activity of abdominal muscle groups when performing trunk curl exercises. Although trunk curl exercises are widely prescribed, a disadvantage of trunk curls is that they primarily activate rectus abdominis, while the internal and external oblique abdominis muscles are considered to be more important contributors to lumbar stability. A convenience sample of 25 subjects performed trunk curl exercises in accordance with 3 different sets of instructions: nonspecific instructions (NS), instructions intended to emphasize rectus abdominis activity (RE), and instructions intended to emphasize oblique abdominis activity (OE). Electromyographic (EMG) activity was recorded from the upper and lower rectus and the internal and external oblique abdominis muscles while a physical target was used to insure that the trunk was raised to the same height for all conditions. Normalized root-mean-square EMG amplitude measures were used to test for instruction-dependent changes in the relative EMG activity of the rectus and oblique muscle groups. Following a single, brief, instruction session, subjects performing trunk curls had significantly greater normalized oblique:rectus EMG ratios when following OE instructions (mean [+/- SD] oblique-rectus ratio, 1.45 +/- 0.34) than when following RE (mean [+/- SD] oblique-rectus ratio, 0.76 +/- 0.24) or NS (mean [ISD] oblique-rectus ratio, 0.63 +/- 0.23) instructions. Retesting 1 week later indicated that subjects retained this skill. With minimal instruction, subjects are able to volitionally alter the relative activity of the oblique and rectus abdominis muscles when performing trunk curls. Incorporating instructions emphasizing oblique abdominis activity into lumbar stabilization programs appears promising and has potential advantages over other approaches to altering abdominal muscle activity during trunk
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We conducted two experiments to assess the effect attentional focus has on learning a complex motor skill and subsequent performance under secondary task loading. Participants in Experiment 1 learnt a golf putting task (300 practice trials) with a single instruction to either focus on their hands (internal focus) or the movement of the putter (external focus). No group differences were evident during learning or retention. Differences between the groups were only apparent under secondary task load; the external group's performance remained robust, while the internal group suffered a drop in performance. Verbal protocols demonstrated that the internal group accumulated significantly more internal knowledge and more task-relevant knowledge in general than the external group. Experiment 2 was designed to establish whether greater internal focus knowledge or greater explicit rule build up in general was responsible for performance breakdown. Two groups were presented with a set of six internal or external rules. Again, no performance differences were found during learning or retention. During the secondary task, both groups experienced performance deterioration. It was concluded that accumulation of explicit rules to guide performance was responsible for the internal group's breakdown in performance under secondary task loading and may be responsible for some of the performance differences reported previously.
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Task-dependent differences in relative activity between "functional" subdivisions within human muscles are well documented. Contrary, independent voluntary control of anatomical subdivisions, termed neuromuscular compartments is not observed in human muscles. Therefore, the main aim of this study was to investigate whether subdivisions within the human trapezius can be independently activated by voluntary command using biofeedback guidance. Bipolar electromyographical electrodes were situated on four subdivisions of the trapezius muscle. The threshold for "active" and "rest" for each subdivision was set to >12% and <1.5% of the maximal electromyographical amplitude recorded during a maximal voluntary contraction. After 1h with biofeedback from each of the four trapezius subdivisions, 11 of 15 subjects learned selective activation of at least one of the four anatomical subdivisions of the trapezius muscle. All subjects managed to voluntarily activate the lower subdivisions independently from the upper subdivisions. Half of the subjects succeeded to voluntarily activate both upper subdivisions independently from the two lower subdivisions. These findings show that anatomical subdivisions of the human trapezius muscle can be independently activated by voluntary command, indicating neuromuscular compartmentalization of the trapezius muscle. The independent activation of the upper and lower subdivisions of the trapezius is in accordance with the selective innervation by the fine cranial and main branch of the accessory nerve to the upper and lower subdivisions. These findings provide new insight into motor control characteristics, learning possibilities, and function of the clinically relevant human trapezius muscle.
Chapter
This chapter focuses on the effect of external attention resources on effortless movements of individuals and concerned importance in enhancing the effectiveness and efficiency of such movements. It examines the findings of studies related to investigations on the effects of different attentional resources on the effectiveness and efficiency of movements. Evidence from the studies reveals that a greater focus on the effects of movements enhances the performance of effortless movement compared with more focus on the movement itself. Some other studies investigating the role of external attention in a variety of sports also reveal that more focus on external sources of movements enhances the results of such efforts.
Article
Over the past 15 years, research on focus of attention has consistently demonstrated that an external focus (i.e., on the movement effect) enhances motor performance and learning relative to an internal focus (i.e., on body movements). This article provides a comprehensive review of the extant literature. Findings show that the performance and learning advantages through instructions or feedback inducing an external focus extend across different types of tasks, skill levels, and age groups. Benefits are seen in movement effectiveness (e.g., accuracy, consistency, balance) as well as efficiency (e.g., muscular activity, force production, cardiovascular responses). Methodological issues that have arisen in the literature are discussed. Finally, our current understanding of the underlying mechanisms of the attentional focus effect is outlined, and directions for future research are suggested.
Article
Research on the focus of attention (FOA) in motor control has found a consistent advantage for focusing externally (on the effects of one's actions) compared to focusing internally (on one's body mechanics). However, most of this work has concentrated on movement outcomes, leaving open the question of how external attention changes the movement itself. Somewhat paradoxically, recent research has found that external attention also increases trial-by-trial movement variability. To explain these findings, we propose a theory of attention in motor control, grounded in optimal control theory, wherein variability is minimized along attended aspects of the movement. Internal attention thus reduces variability in individual bodily dimensions (positions and velocities of effectors), whereas external attention minimizes variability in the task outcome. Because the goal of a task defines a dimension in the movement space that is generally oblique to bodily dimensions, external attention should increase correlations among bodily dimensions while allowing their individual variances to grow. The current experiment tests these predictions in a dart-throwing task. External FOA led to more accurate performance and increased variability in the motion of the throwing arm, concomitant with stronger correlations among bodily dimensions (shoulder, elbow, and wrist positions and velocities) in a manner consistent with the task kinematics. These findings indicate a shift in the control policy of the motor system, consistent with the proposed theory. These results suggest an important role of attention as a control parameter in the regulation of the motor system, and more broadly illustrate the importance of cognitive mechanisms in motor behavior. (PsycINFO Database Record (c) 2013 APA, all rights reserved).
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.
Article
Research on the focus of attention has begun exploring the physiological changes that underlie the difference between internal and external foci of attention. However, previous electromyography studies have used dynamic tasks, making it difficult to interpret electrophysiological data. The authors analyzed how the focus of attention affects a subject's ability to perform an isometric force production task (focus was directed either at the force platform or the muscles responsible for force production). Subjects received practice without attentional focus instructions and then completed blocks of trials with an external and internal attentional focus separately. An external focus led to significantly less error overall and reduced surface electromyography activity with lower median power frequencies in the antagonist muscle, but attentional focus had no effects on the agonist muscle. Thus, an external focus of attention led to more efficient motor unit recruitment patterns (reduced cocontraction) and improved performance. Posttest surveys revealed subjects were aware of their improved performance with an external focus.
Article
Research has found an advantage for an external focus of attention in motor control and learning; instructing subjects to focus on the effects of their actions, rather than on body movements, can improve performance during training and retention testing. Previous research has mostly concentrated on movement outcomes, not on the quality of the movement itself. Thus, this study combined surface electromyography (EMG) with motion analysis and outcome measures in a dart throwing task, making this the first study that includes a comprehensive analysis of changes in motor performance as a function of attentional focus. An external focus of attention led to better performance (less absolute error), decreased preparation time between throws, and reduced EMG activity in the triceps brachii. There was also some evidence of increased variability for kinematic measures of the shoulder joint under an external focus relative to an internal focus. These results suggest improved movement economy with an external focus of attention.
Article
Jump height is increased when performers are given external focus instructions, relative to an internal focus or no focus instructions (Wulf & Dufek, 2009; Wulf, Zachry, Granados, & Dufek, 2007). The purpose of present study was to examine possible underlying neurophysiological mechanisms of this effect by using electromyography (EMG). Participants performed a vertical jump-and-reach task under two conditions in a counterbalanced order: external focus (i.e., focus on the rungs of the measurement device) and internal focus (i.e., focus on the fingers with which the rungs were to be touched). EMG activity of various muscles (anterior tibialis, biceps femoris, vastus lateralis, rectus femoris, gastrocnemius) was measured during jumps. Jump height was greater with an external compared to an internal focus. While there were no differences in muscle onset times between attentional focus conditions, EMG activity was generally lower with an external focus. These results suggest that neuromuscular coordination is enhanced by an external focus of attention. The present findings add to the evidence that an external focus facilitates the production of effective and efficient movement patterns.
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.
Article
Feedback about motor performance can induce either an internal focus of attention (about body movement) or an external focus of attention (about the effects on the environment) in the learner. The main aim of this pilot study was to examine the attentional focus of feedback given by physiotherapists during treatment of the hemiplegic arm. A second aim was to examine the frequency of feedback about motor performance during treatment. A multi-methods design was used (quantitative and qualitative). Eight physiotherapists and eight patients with stroke were recruited from two hospitals. Data were collected by video recordings of treatment, interviews (both therapists and patients) and questionnaire (therapists). Information feedback, instructions and motivational statements were identified from the video recordings. Feedback and instructions were further grouped into internal focus, external focus or mixed focus of attention. Themes were drawn from the interview transcripts. Triangulation was used to provide corroborating information from the different data sets. Two hundred and forty-six of the total 1914 statements identified in the videos were feedback, the rest comprising instructions and statements of motivation. Of the feedback statements, 236 of the total 247 identified had an internal focus. Therapist interviews and questionnaires revealed more external focus communication than actual treatment. Physiotherapists used instructions and statements of motivation more than feedback and directed the patient's attention more to body movement than movement effects. The outcome of this study may prompt clinicians' to examine the amount and the attentional focus of the feedback they use in their clinical practice, and to consider whether it is a most effective approach in light of current evidence.
Article
This study was focused on the ability to reduce voluntarily the muscle activity in the descending part of the trapezius muscle without changing the arm position or hand load, and its consequences on the distribution of shoulder muscle forces. Visual feedback techniques were used. Six different arm positions were investigated in 11 subjects. Electromyography was used for monitoring the muscle involvement. The selection of relevant muscles was performed by a model simulation of the shoulder using a newly developed biomechanical model of the human shoulder. The ability to reduce the muscle activity of the descending part of the trapezius was confirmed and the reduction ranged from 60 to 76% depending on the arm position. Among the muscles studied the rhomboid major and minor and the transverse part of the trapezius were affected the most, increasing their activity on the average to 232, 175 and 201% respectively, compared to the initial activity. The anterior part of the deltoid and the medial part of the serratus anterior also intensified their activity. The influence on the levator scapulae was, contrary to simulation results and to empirical knowledge, a decrease of the muscle activity. It is suggested that attention is given to the rhomboids and the transverse part of the trapezius when muscle activity is reduced in the descending part of the trapezius, for instance in biofeedback-based therapy. In conclusion, the study showed that reducing the trapezius activity caused a redistribution of muscle forces in the shoulder.
Article
The knowledge of surface electromyography (SEMG) and the number of applications have increased considerably during the past ten years. However, most methodological developments have taken place locally, resulting in different methodologies among the different groups of users.A specific objective of the European concerted action SENIAM (surface EMG for a non-invasive assessment of muscles) was, besides creating more collaboration among the various European groups, to develop recommendations on sensors, sensor placement, signal processing and modeling. This paper will present the process and the results of the development of the recommendations for the SEMG sensors and sensor placement procedures. Execution of the SENIAM sensor tasks, in the period 1996-1999, has been handled in a number of partly parallel and partly sequential activities. A literature scan was carried out on the use of sensors and sensor placement procedures in European laboratories. In total, 144 peer-reviewed papers were scanned on the applied SEMG sensor properties and sensor placement procedures. This showed a large variability of methodology as well as a rather insufficient description. A special workshop provided an overview on the scientific and clinical knowledge of the effects of sensor properties and sensor placement procedures on the SEMG characteristics. Based on the inventory, the results of the topical workshop and generally accepted state-of-the-art knowledge, a first proposal for sensors and sensor placement procedures was defined. Besides containing a general procedure and recommendations for sensor placement, this was worked out in detail for 27 different muscles. This proposal was evaluated in several European laboratories with respect to technical and practical aspects and also sent to all members of the SENIAM club (>100 members) together with a questionnaire to obtain their comments. Based on this evaluation the final recommendations of SENIAM were made and published (SENIAM 8: European recommendations for surface electromyography, 1999), both as a booklet and as a CD-ROM. In this way a common body of knowledge has been created on SEMG sensors and sensor placement properties as well as practical guidelines for the proper use of SEMG.
Article
The performance and learning of motor skills has been shown to be enhanced if the performer adopts an external focus of attention (focus on the movement effect) compared to an internal focus (focus on the movements themselves) [G. Wulf, W. Prinz, Directing attention to movement effects enhances learning: a review, Psychon. Bull. Rev. 8 (2001) 648-660]. While most previous studies examining attentional focus effects have exclusively used performance outcome (e.g., accuracy) measures, in the present study electromyography (EMG) was used to determine neuromuscular correlates of external versus internal focus differences in movement outcome. Participants performed basketball free throws under both internal focus (wrist motion) and external focus (basket) conditions. EMG activity was recorded for m. flexor carpi radialis, m. biceps brachii, m. triceps triceps brachii, and m. deltoid of each participant's shooting arm. The results showed that free throw accuracy was greater when participants adopted an external compared to an internal focus. In addition, EMG activity of the biceps and triceps muscles was lower with an external relative to an internal focus. This suggests that an external focus of attention enhances movement economy, and presumably reduces "noise" in the motor system that hampers fine movement control and makes the outcome of the movement less reliable.