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Evidence-Based Personal Training
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COLUMN EDITOR: Brad Schoenfeld, PhD, CSCS,
Attentional Focus for
Maximizing Muscle
Development: The
Mind-Muscle Connection
Brad J. Schoenfeld, PhD, CSCS, FNSCA
and Bret Contreras, MA, CSCS
Department of Health Sciences, Program of Exercise Science, City University of New York, Lehman College, New
York, New York; and
Sport Performance Research Institute, AUT University, Auckland, New Zealand
ttentional focus is a well-
recognized aspect of motor
learning and its use has impor-
tant implications to the tness profes-
sional. Simply stated, attentional focus
refers to what an individual thinks about
when performing a given movement or
activity . Two primary types of atten-
tional focuses have been identified:
internal and external. With an internal
focus, the individual thinks about bodily
movements during performance. Alter-
natively, an external focus directs the
exerciser’s attention to the environment.
For example, in the squat an internal
focus could be to “squeeze your glutes
as you ascend” whereas an external
focus could be to “drive the floor away
from your body.” This article will discuss
how attentional focus should be d irected
to maximize muscular development.
A compelling body of research indi-
cates that performance-oriented tasks
are optimized by adopting an external
focus of attention. In a recent review of
literature encompassing over 50 pub-
lished studies on the topic, Wulf (12)
found that more than 90% of these
studies showed superior improvements
in motor learning when subjects used
an external compared with internal
focus. Beneficial effects were seen
across a wide variety of activities and
outcome measures, lending strong sup-
port for the use of an external focus
when the goal is to boost performance.
With respect to resistance training, the
performance-based superiority of an
external focus has been attributed to
an enhanced economy of movement
associated with greater force produc-
tion and reduced muscular activity (5).
However, whereas a more economical
movement pattern facilitates better skill
acquisition, it may not be optimal for
muscle development. Indeed, when
the goal is to maximize hypertrophy,
indirect evidence suggests that an inter-
nal focus may be the best approach.
Bodybuilders have long preached the
importance of developing a “mind-
muscle connection” when training. This
internally focused strategy involves visu-
alizing the target muscle and consciously
directing neural drive to the muscle dur-
ing exercise performance. Theoretically,
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Copyright ª National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.
such an approach would increase acti-
vation of the target muscle while dimin-
ishing contribution from secondary
muscle movers. Indeed, research seems
to support this contention.
A number of studies have shown
greater activation of a given muscle
when subjects were instructed to adopt
an internal focus of attention. This has
been most prominently displayed in
the abdominal musculature. Karst and
Willett (3) found that subjects were
able to significantly alter mean electro-
myography (EMG) activity to either
the rectus abdominis or obliques by
consciously focusing on the respective
muscles during performance of the curl
up. Before engaging in exercise, sub-
jects in this study were instructed on
how to visualize either the rectus or
obliques and verbal reinforcement of
these instructions were provided dur-
ing performance. A control condition
involved focusing on the movement
itself without regard to any specific
muscles. These results are consistent
with research showing increased acti-
vation of the transversus abdominis
after instruction to tighten the pelvic
floor muscles (2). Similarly, Bressel
et al. (1) demonstrated that mean and
peak EMG amplitude were significantly
increased in both superficial and deep
abdominal musculature during the
squat when subjects were directed to
“brace yourself as if you were going to
be punched in the stomach.
Findings of heightened EMG activity
from an internal focus have been noted
in other muscles as well. Lewis and
Sahrmann (4) showed that young
women were able to achieve greater
mean EMG activity of the gluteus
maximus and reduced activation of
the hamstrings when cued to contract
the gluteal muscles during perfor-
mance of the prone hip extension
(“Use your gluteal muscles to lift your
leg while keeping your hamstrings
muscles relaxed”). Moreover, the tim-
ing of activation was altered so that
the gluteus maximus was activated sig-
nificantly earlier during movement.
Likewise, research has shown that
intentionally focusing on the target
muscle resulted in higher activation
of the latissimus dorsi, pectoralis major,
biceps brachii, and triceps brachii (5,7–
9). Interestingly, evidence seems to
indicate that the increased activation
does not always coincide with reduc-
tions in the activity of secondary mus-
cle movers (7,8).
Although it remains unclear as to
whether increased muscle activation
translates into greater muscle protein
accretion, emerging research indicates
that this may in fact be the case. In a 2-
part experiment, Wakahara et al. (11)
first investigated acute muscle activation
in 12 untrained men after a single bout
of resistance training for the elbow ex-
tensors through T2-weighted magnetic
resonance imaging. The exercise proto-
col consisted of 5 sets of 8 repetitions of
lying triceps extensions with 90 seconds
rest between sets. Results showed sig-
nificantly greater activation in the prox-
imal and mid-portions of the triceps
brachii compared with the distal aspect.
Another 12 subjects were then recruited
to perform a 3-day-per-week program
consisting of the same routine used in
part 1 of the study. After 12 weeks of
regimented training, increases in muscle
cross-sectional area were found to be
well-correlated to the areas most acti-
vated by the exercise regimen. Follow-
up work by the same laboratory showed
similar results using different triceps bra-
chii exercises (10), which in combina-
tion provide evidence for an association
between activation levels and muscle
growth. It should be noted that these
studies did not attempt to investigate
muscle activation in conjunction with
altered attentional focus, so it is unclear
whether results would translate to the
adoption of an internal focus. Moreover,
the results of these studies are specific to
the triceps brachii and thus cannot nec-
essarily be generalized to other muscles.
Interestingly, the effectiveness of using
an internal focus is reduced when
training at higher loads. Snyder and
Fry (7) found that activation of the pec-
torals was amplified by 22% when
resistance-trained men were provided
with verbal instructions to focus on the
chest muscles during bench press at
50% 1 repetition maximum (1RM).
However, the magnitude of this effect
decreased to 13% when the same in-
structions were provided during per-
formance at 80% 1RM. This may be
a function of needing to exert greater
levels of force when training at heavier
loads, thereby altering one’s ability to
focus on the muscle being worked.
Moreover, in accordance with the size
principle, fewer motor units will be
available for the mind to influence with
heavy loading when compared with
lighter loads. This suggests that adopt-
ing an internal attentional focus with
very heavy loads (above 85–90% of
1RM) is unnecessary because it might
limit force production without enhanc-
ing muscle activation, but more
research is needed in subjects with
varying levels of experience to explore
this hypothesis.
Attentional f ocus should match the
goal of the task. Competitive sport
athletes should rely heavily on exter-
nal attentional focus in practice and
during games or matches. This in-
cludes powerlifters, weightlifters, or
strongmen seeking to set a 1RM or
to maximize force or tor que produc-
tion; basketball players or track &
field athletes seeking to maximize
jump height or distance; runners or
rowers seeking to improve economy;
and dart throwers, golfers, and pool
players seeking maximum accuracy.
Alternatively, when attempting to
maximize muscle activation, an inter-
nal focus of attention would seem to
be a better choice. Bodybuilders, phy-
sique athletes, and others seeking
maximal hypertrophy will conceiv-
ably benefit by focusing on the target
muscle during an exercise rather than
on the outcome or environment. It is
likely that the molecular signaling for
all 3 primary mechanisms of muscular
hypertrophy, namely mechanical ten-
sion, metabolic stress, and muscle
damage (6), are increased when the
exerciser focuses their attention inter-
nally, which could ultimately result in
greater muscular development for
a given exercise and load. The effects
Evidence-Based Personal Training
Copyright ª National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.
of this strategy seem to be particularly
beneficial when training with rela-
tively light loads.
Conflicts of Interest and Source of Funding:
The authors report no conflicts of interest
and no source of funding.
Brad J. Schoenfeld is an assistant
professor in the exercise science program
at CUNY Lehman College and director
of their human performance laboratory.
Bret Contreras is currently pursuing
his PhD in Sports Science at the Auck-
land University of Technology in Auck-
land, New Zealand.
1. Bressel E, Willardson JM, Thompson B, and
Fontana FE. Effect of instruction, surface
stability, and load intensity on trunk muscle
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2. Critchley D. Instructing pelvic floor
contraction facilitates transversus abdominis
thickness increase during low-abdominal
hollowing. Physiother Res Int 7: 65–75,
3. Karst GM and Willett GM. Effects of
specific exercise instructions on abdominal
muscle activity during trunk curl exercises.
J Orthop Sports Phys Ther 34: 4–12,
4. Lewis CL and Sahrmann SA. Muscle
activation and movement patterns during
prone hip extension exercise in women.
J Athl Train 44: 238–248, 2009.
5. Marchant DC, Greig M, and Scott C.
Attentional focusing instruct ions
influence force production and muscular
activity during isok inetic elbow flexio ns.
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8. Snyder BJ and Leech JR. Voluntary increase
in latissimus dorsi muscle activity during the
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10. Wakahara T, Fukutani A, Kawakami Y, and
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11. Wakahara T, Miyamoto N, Sugisaki N,
Murata K, Kanehisa H, Kawakami Y,
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Strength and Conditioning Journal |
Copyright ª National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.
... The trainer said that beginner trainees do not often know the specifc names of the muscles mentioned in videos, hence the opportunity to augment with a visualization. We chose this type of cue because, as mentioned by [61], when the goal is to maximise muscle engagement, internal instructional cues work better than external ones, as they focus on directing the attention towards the body [19]. Additionally, Study 1 showed that during strength training sessions people tended to naturally direct their attention inwards, specifcally towards the muscles they felt active during the exercise, in order to self-evaluate their performance. ...
... As with Study 1, we favoured a combination of deductive and inductive coding; the former due to the theoretical foundation of the study and as a way to simplify the connection of relevant fndings to previous literature, the latter due to the pragmatic nature of the study and the interest in case-related fndings [36]. Theories that informed the top-down approach relate to attention [40], the learning process [31,44], imagery and what enables it [46,64,65], information overload and what causes it [40,68,72], and the reception of the intended meaning of the cues, as discussed in [61,65,68]. As in Study 1, the frst author of this paper led the analysis, all throughout which the codes and constructed themes were frequently discussed, contrasted, and polished with the second author. ...
... Despite the reported vagueness of this type of cue for some of the participants, they also saw value in conveying the information of muscle engagement -even considering it essential for the correct execution of the exercises themselves. Overall, this cue's efect aligns with prior knowledge that internal instructional cues can be used successfully to direct the attention of the trainees towards their own bodies and muscle activation [61], demonstrating that highlighting body parts can successfully achieve such results. Our fndings also surface the need to further explore if more nuanced body highlights (e.g., depicting particular muscles instead of general muscle areas) would help enhance instructions even more. ...
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Instructional videos for physical training have gained popularity in recent years among sport and ftness practitioners, due to the proliferation of afordable and ubiquitous forms of online training. Yet, learning movement this way poses challenges: lack of feedback and personalised instructions, and having to rely on personal imitation capacity to learn movements. We address some of these challenges by exploring visual cues’ potential to help people imitate movements from instructional videos. With a Research through Design approach, focused on strength training, we augmented an instructional video with diferent sets of visual cues: directional cues, body highlights, and metaphorical visualizations. We tested each set with ten practitioners over three recorded sessions, with follow-up interviews. Through thematic analysis, we derived insights on the efect of each set of cues for supporting movement learning. Finally, we generated design takeaways to inform future HCI work on visual cues for instructional training videos.
... The results indicated that adopting an external focus of attention enhanced motor learning [2]. Since then, many studies have examined the effects of attentional focus on various tasks [1][2][3][4][5][6]. Currently, there is agreement that an external focus of attention enhances different aspects of motor performance, such as accuracy, consistency, and balance [1][2][3]. ...
... While the effects of attentional strategies have been explored for various exercise tasks, the influence of external vs. internal focus on resistance exercise has received less attention. Several studies explored the effects of attentional focus on resistance exercise [4][5][6]. For example, in the study by Vance et al. [5], participants performed bicep curls with instructions to concentrate on their arms (internal focus) or on the barbell (external focus). ...
... This study observed that integrated electromyography (EMG) activity was lower in the external focus condition [5]. Previous studies focused on the EMG-derived outcomes, likely because of the suggested importance of the "mind-muscle" connection in resistance exercise [6]. While the findings presented in these studies are certainly of interest, they do not provide us with insights into the effects of external vs. internal focus on resistance exercise performance. ...
Full-text available
Several studies explored the effects of attentional focus on resistance exercise, but their analysed outcomes most commonly involved surface electromyography variables. Therefore, the effects of attentional focus on resistance exercise performance remain unclear. The aim of this review was to perform a meta-analysis examining the acute effects of external focus vs. internal focus vs. control on muscular endurance. Five databases were searched to find relevant studies. The data were pooled in a random-effects meta-analysis. In the analysis for external vs. internal focus of attention , there were seven comparisons with 14 study groups. In the analyses for external focus vs. control and internal focus vs. control, there were six comparisons with 12 study groups. An external focus of attention enhanced muscular endurance when compared with an internal focus (Cohen's d: 0.58; 95% confidence interval (CI): 0.34 and 0.82) and control (Cohen's d: 0.42; 95% CI: 0.08 and 0.76). In the analysis for internal focus vs. control, there was no significant difference between the conditions (Cohen's d:-0.19; 95% CI:-0.45 and 0.07). Generally, these results remained consistent in the subgroup analyses for upper-body vs. lower-body exercises. From a practical perspective, the results presented in this review suggest that individuals should use an external focus of attention for acute enhancement of muscular endurance.
... An internal focus alludes to a mind-body or mind-muscle connection where an individual can consciously control muscle activation by thinking of creating tension in the target muscle. Schoenfeld and Contreras (2) suggested that an individual can effectively focus on the target muscle of the exercise, thereby diminishing the contributions of other muscles. In case study 2, the client was capable of producing more power in their movement with external focus perhaps by using multiple muscle groups to perform the exercise. ...
... Studies have suggested a mind-body connection for maximizing muscle activation by applying an internal focus on specific muscle groups over others in a compound movement. For example, while performing a curl-up, when focusing on isolating the rectus abdominis contraction, the electromyographic activity increased in the rectus abdominis and reduced in the obliques and vice versa when focusing on the obliques when compared with a control group directed to focus on the movement with no mention of muscles targeted (2). Personal trainers can use this strategy in single-joint exercises to isolate the agonists more effectively or to develop specific muscles in a multijoint exercise such as varying the focus between pectoralis major, anterior deltoid, or triceps brachii in a chest press depending on the goal of the client. ...
... When a client's goal is targeting strength endurance (e.g., repetitions to failure) or maximal force production such as in a heavily loaded squat or a weighted pull-up, external cues relating to the bar or floor are most effective for performance. With heavier loads, to overcome the weight, more instructions may be necessary not only to contract the target muscles but also to maintain the pathway of the bar or provide further encouragement (2). This suggests that in complex movements where force production, strength, and speed are paramount, external focus cues are the best choice for efficiency of movement. ...
Full-text available
• Explore how attentional focused cues affect performance based on exercise modality and intensity. • Identify how and when to apply cues that target internal or external focus to optimize training for clients.
... Muscle activity during exercise differs depending on an individual's focus attention when lifting an external resistance, even with the same load of resistance (Neumann, 2019;Schoenfeld and Contreras, 2016). In the case of resistance training, internal focus of attention (INT) means the individual concentrates on contracting the agonist muscle when lifting a weight, while external focus of attention (EXT), on lifting the weight. ...
... In the case of resistance training, internal focus of attention (INT) means the individual concentrates on contracting the agonist muscle when lifting a weight, while external focus of attention (EXT), on lifting the weight. Previous reviews (Neumann, 2019;Schoenfeld and Contreras, 2016) reported that although higher electromyographic (EMG) activity in the agonist muscle is observed in INT as compared to EXT, movement velocity (including angular velocity or power production) during exercise is executed faster in EXT than in INT. Therefore, these previous studies suggest that if muscle strength gain or muscle hypertrophy gain is the desired goal, then INT should be used during exercise. ...
... The average %MVC in the INT and INT+T focus conditions were significantly higher than that in the EXT condition. Increased agonist muscular activity is observed in the INT as compared to the EXT is consistent with the results of previous studies (Neumann, 2019;Oshita et al., in press;Schoenfeld and Contreras, 2016;Vance et al., 2004). Although antagonist muscle activity was not measured in this study, a previous study reported that associated increase in the antagonist muscle activity was in line with the agonist muscle activity during INT. ...
... No presente estudo, o encorajamento verbal ea atenção do indivíduo para o exercício realizado podem ter afetado os resultados obtidos. A orientação para um exercício pode direcionar um indivíduo a focar sua atenção nos movimentos corporais e grupos musculares (foco interno) ou focar sua atenção no exercício e no ambiente (foco externo) 18,19 . Um exemplo disso é orientar durante o exercício agachamento "contraia o glúteo na subida" (foco interno) ou "empurre a barra para cima" (foco externo) [18] . ...
... A orientação para um exercício pode direcionar um indivíduo a focar sua atenção nos movimentos corporais e grupos musculares (foco interno) ou focar sua atenção no exercício e no ambiente (foco externo) 18,19 . Um exemplo disso é orientar durante o exercício agachamento "contraia o glúteo na subida" (foco interno) ou "empurre a barra para cima" (foco externo) [18] . Estudos indicam ser possível enfatizar a ativação de certos grupos musculares em um exercício utilizando o foco interno 20,21 ; entretanto, a revisão realizadas por Wulf 19 demonstra que o desempenho em atividades força-dependentes (resistência de força, força máxima isométrica/dinâmica e potência) é maior quando os praticantes são orientados a focar externamente na atividade. ...
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Supervised resistance training may affect several acute variables such as volume load (VL), the maximum number of repetitions (NRM), time under tension (TUT), and rate of perceived exertion (RPE) in resistance trained-men. The present study aimed to evaluate the influence of the personal trainer’s supervision on a resistance training session in resistance trained-men. Fifteen resistance-trained men (20,0±2 years; 176,0±4 cm; 79,3±4,7 kg) performed two training sessions composed of whole-body exercises. In the session without personal trainer’s supervision (NPT) the subjects self-selected their loads for each exercise and were oriented to “select a load typically employed to perform 10 repetitions”; in the session with personal trainer’s supervision (WPT) the subjects self-selected their loads for each exercise and were oriented to “perform maximum effort”. It was observed greater VL (P<0,001, Δ%=30), NRM (P<0,001, Δ%=29), TUT (P=0,003, Δ%=21), and RPE (P<0,001, Δ%=29) in the resistance training session WPT. The present study concluded that supervised sessions positively affect resistance training variables.
... For example, Wulf and Lewthwaite found that the increased muscular accuracy of force production created by increased attention control allows an athlete to lift the same weight with less muscular effort (26). Whether an athlete is internally focused on squeezing their glutes as they ascend or externally focused on driving the floor away from their body (20), it seems clear that reliable attentional control and awareness are valuable skills when lifting weights during strength training (19,26). ...
... Once it has 2 compartments, and each 1 has its own innervations, this may turn it possible to increase the recruitment of a specific portion selectively (1,14,19). Thus, the strategy used to focus on "squeezing" the muscles during each repetition might have also contributed to current findings because this tends to increase the activation of the targeted muscles (21,26,27). Moreover, it can be speculated that, during the calf-raise exercises, FPO and FPI conditions caused greater specific stretching of the medial and lateral heads of the gastrocnemius, respectively. ...
Full-text available
The aim of the present study was to compare the changes in gastrocnemius muscle thickness (MT) between conditions in which foot was pointed outward (FPO), inward (FPI), or forward (FPF). Twenty-two young men (23 ± 4 years) were selected and performed a whole-body resistance training program three times per week for nine weeks, with differences in the exercise specific for calves. Calf-raise exercise was performed unilaterally, in a pin-loaded seated horizontal leg-press machine, in 3 sets of 20-25 repetitions for training weeks 1-3, and 4 sets for weeks 4-9. Each subject's leg was randomly assigned for one of the three groups according to foot position: FPO, FPI, and FPF. Measurements with a B-mode ultrasound were performed to assess changes in MT of medial and lateral gastrocnemius heads. After training period, there were observed increases in MT of both medial (FPO = 8.4%; FPI = 3.8%; FPF = 5.8%) and lateral (FPO = 5.5%; FPI = 9.1%; FPF = 6.4%) gastrocnemius, and significant differences for magnitude of the gains were observed between FPO and FPI conditions (P < 0.05). Positioning FPO potentiated the increases in MT of medial gastrocnemius, while FPI provided greater gains for the lateral head. Our results suggest that head-specific muscle hypertrophy may be obtained selectively for gastrocnemius after nine weeks of calf training in young male adults.
This study aimed to investigate the effect of tactile stimulation by touching the agonist muscle during the arm curl exercise. Nine healthy males (age, 20–35 years) performed five repetitions of arm curl under two different focus instructions; for the external focus condition, participants were instructed to lift the bar, whereas for the internal focus condition, the participants’ biceps brachii was lightly touched by the investigator and they were instructed to concentrate on muscle contraction at the touched point. Muscular activity in the biceps brachii was evaluated during the exercise. The muscle activity in the internal focus condition was significantly greater than that of the external focus condition (P = 0.01, d = 0.19). This result suggests that internal focus caused by an individual’s consciousness, as well as a focus attention through touching the agonist area increased the agonist muscle activity.
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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.
The main objective of this study was to investigate the effects of focus of attention among novice and elite athletes influenced the performance of short distance sprint (20 m) and maximum velocity speed (40 m). Sixty participants novice (n = 30) and elite (30) completed two trials for 20 m and 40 m sprint pre and post-test. Both novice and elite participants were randomly assigned to an internal focus group (IF), external focus group (EF) and control group (CONT). The IF group were focusing on component of body movement whilst EF group focusing on the movement outcomes. Then CONT group with no specific instruction. The participants involved three times per week for a month. Results shows in 20 m sprint test, there was a significant difference in IF and control group (novice) and EF, IF and CONT group (elite). While for 40 m sprint test, there was a significant different for IF and control group for novice. However, for elite athletes results shows a significant different in EF group. Overall finding indicates, adopting and external focus attention for novice and elites athletes enhance in reduction of times (second) in sprinting performance. Moreover, adopting external focus instruction resulted in shorter time (sec) among novice and elite athletes in sprinting performance.
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The quest to increase lean body mass is widely pursued by those who lift weights. Research is lacking, however, as to the best approach for maximizing exercise-induced muscle growth. Bodybuilders generally train with moderate loads and fairly short rest intervals that induce high amounts of metabolic stress. Powerlifters, on the other hand, routinely train with high-intensity loads and lengthy rest periods between sets. Although both groups are known to display impressive muscularity, it is not clear which method is superior for hypertrophic gains. It has been shown that many factors mediate the hypertrophic process and that mechanical tension, muscle damage, and metabolic stress all can play a role in exercise-induced muscle growth. Therefore, the purpose of this paper is twofold: (a) to extensively review the literature as to the mechanisms of muscle hypertrophy and their application to exercise training and (b) to draw conclusions from the research as to the optimal protocol for maximizing muscle growth.
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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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The consistency of muscle activation order during prone hip extension has been debated. To investigate whether women use a consistent and distinguishable muscle activation order when extending the hip while prone and to explore the effects of verbal cues on muscle activation and movement. Single-session, repeated-measures design. University laboratory. Eleven healthy women (age = 27.7 +/- 6.2 years [range, 22-37 years]). We tested the participants under 3 conditions: no cues, cues to contract the gluteal muscles, and cues to contract the hamstrings muscles. We measured hip and knee angle and electromyographic data from the gluteus maximus, medial hamstrings, and lateral hamstrings while participants performed prone hip extension from 30 degrees of hip flexion to neutral. When not given cues, participants used the consistent and distinguishable muscle activation order of medial hamstrings, followed by lateral hamstrings, then gluteus maximus (195.5 +/- 74.9, 100.2 +/- 70.3, and 11.5 +/- 81.9 milliseconds preceding start of movement, respectively). Compared with the no-cues condition, the gluteal-cues condition resulted in nearly simultaneous onset of medial hamstrings, lateral hamstrings, and gluteus maximus (131.3 +/- 84.0, 38.8 +/- 96.9, and 45.1 +/- 93.4 milliseconds, respectively) (P > .059); decreased activation of the medial hamstrings (P < .03) and lateral hamstrings (P < .024) around the initiation of movement; increased activation of gluteus maximus throughout the movement (P < .001); and decreased knee flexion (P = .002). Compared with the no-cues condition, the hamstrings-cues condition resulted in decreased activation of the medial hamstrings just after the initiation of movement (P = .028) and throughout the movement (P = .034) and resulted in decreased knee flexion (P = .003). Our results support the contention that the muscle activation order during prone hip extension is consistent in healthy women and demonstrates that muscle timing and activation amplitude and movement can be modified with verbal cues. This information is important for clinicians using prone hip extension as either an evaluation tool or a rehabilitation exercise.
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.
Purpose: Muscle hypertrophy in response to resistance training has been reported to occur nonuniformly along the length of the muscle. The purpose of the present study was to examine whether the regional difference in muscle hypertrophy induced by a training intervention corresponds to the regional difference in muscle activation in the training session. Methods: Twelve young men participated in a training intervention program for the elbow extensors with a multijoint resistance exercise for 12 wk (3 d · wk(-1)). Before and after the intervention, cross-sectional areas of the triceps brachii along its length were measured with magnetic resonance images. A series of transverse relaxation time (T2)-weighted magnetic resonance images was recorded before and immediately after the first session of training intervention. The T2 was calculated for each pixel within the triceps brachii. In the images recorded after the session, the number of pixels with a T2 greater than the threshold (mean + 1 SD of T2 before the session) was expressed as the ratio to the whole number of pixels within the muscle and used as an index of muscle activation (percent activated area). Results: The percent activated area of the triceps brachii in the first session was significantly higher in the middle regions than that in the most proximal region. Similarly, the relative change in cross-sectional area induced by the training intervention was also significantly greater in the middle regions than the most proximal region. Conclusion: The results suggest that nonuniform muscle hypertrophy after training intervention is due to the region-specific muscle activation during the training session.
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.
The purpose of this study was to examine if the regional difference in muscle hypertrophy after chronic resistance training is associated with muscle activation after one session of resistance exercise. Twelve men performed one session of resistance exercise of elbow extensors. Before and immediately after the exercise, transverse relaxation time (T2)-weighted magnetic resonance (MR) images of upper arm were recorded to evaluate the muscle activation along its length. In the MR images, T2 for the pixels within the triceps brachii muscle was quantified. The number of pixels with T2 greater than the threshold (mean + 1SD of T2 before the exercise) was expressed as the ratio to the number of pixels occupied by the muscle (%activated area). Another 12 subjects completed 12 weeks of training intervention (3 days per week), which consisted of the same program variables as used in the experiment for the T2 measurement. The cross-sectional areas of the triceps brachii before and after the training intervention were measured from MR images of upper arm. The %activated area of the triceps brachii induced by one session of the exercise was found to be significantly lower in the distal region than the middle and proximal regions. Similarly, the relative increase in muscle cross-sectional area after the 12 weeks of training intervention was significantly less in the distal region than the middle and proximal regions. The results suggest that the regional difference in muscle hypertrophy after chronic resistance training is attributable to the regional difference in muscle activation during the exercise.
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.
The aim of this study was to assess the effect of verbal instruction, surface stability, and load intensity on trunk muscle activity levels during the free weight squat exercise. Twelve trained males performed a free weight squat under four conditions: (1) standing on stable ground lifting 50% of their 1-repetition maximum (RM), (2) standing on a BOSU balance trainer lifting 50% of their 1-RM, (3) standing on stable ground lifting 75% of their 1-RM, and (4) receiving verbal instructions to activate the trunk muscles followed by lifting 50% of their 1-RM. Surface EMG activity from muscles rectus abdominis (RA), external oblique (EO), transversus abdominis/internal oblique (TA/IO), and erector spinae (ES) were recorded for each condition and normalized for comparisons. Muscles RA, EO, and TA/IO displayed greater peak activity (39-167%) during squats with instructions compared to the other squat conditions (P=0.04-0.007). Peak EMG activity of muscle ES was greater for the 75% 1-RM condition than squats with instructions or lifting 50% of 1-RM (P=0.04-0.02). The results indicate that if the goal is to enhance EMG activity of the abdominal muscles during a multi-joint squat exercise then verbal instructions may be more effective than increasing load intensity or lifting on an unstable surface. However, in light of other research, conscious co-activation of the trunk muscles during the squat exercise may lead to spinal instability and hazardous compression forces in the lumbar spine.
Low abdominal hollowing in four-point kneeling is used clinically to test and rehabilitate transversus abdominis (TrA) but many people find this exercise difficult to perform. Contracting pelvic floor muscles (PF) during low abdominal hollowing may facilitate contraction of TrA. Thickness increase in the abdominal muscles during low abdominal hollowing has been measured with real-time ultrasound scanning and may indicate muscle contraction. The present study investigated the effect of instructing PF contraction on TrA thickness increase during low abdominal hollowing. Twelve females and eight males with no reported pelvic floor dysfunction or low back pain in the last two years were taught low abdominal hollowing in four-point kneeling. Subjects performed low abdominal hollowing with and without instruction to contract PF in random order. Transversus abdominis, obliquus internus (OI) and obliquus externus (OE) thickness were measured with ultrasound scanning at rest and during both tests. Mean increase in TrA thickness during low abdominal hollowing was 49.71% (SD 26.76%), during low abdominal hollowing with PF it was 65.81% (SD 23.53%). Paired Student's t-tests indicated a significant difference between tests (p = 0.015). There were no significant differences between tests for OE or OI thickness increase. Instructing healthy subjects to co-contract PF results in greater increase in TrA thickness during low abdominal hollowing in four-point kneeling. This may indicate greater contraction of TrA and thus be useful for clinicians training TrA. Further research could investigate the validity of change of thickness as a measure of abdominal muscle contraction, investigate the effect of instructing PF co-contraction on TrA in patients with low back pain and measure PF and TrA activity simultaneously.