No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Effects of Body Position and Loading Modality on Muscle Activity and Strength in Shoulder Presses
Abstract
Little is known about the effect of performing upper-body resistance exercises with dumbbells versus barbells and standing versus seated. Therefore, this study sought to compare electromyogram activity (EMG) and one-repetition maximum (1-RM) in barbell and dumbbell shoulder presses performed seated and standing. 15 healthy men volunteered for 1-RM and EMG testing with a load corresponding to 80% of the 1-RM. EMG was measured in the anterior, medial and posterior deltoids, and biceps and triceps brachii. The following EMG differences or trends were observed: For deltoid anterior: ∼11% lower for seated barbell versus dumbbell (P=0.038), ∼15% lower in standing barbell versus dumbbell (P<0.001), ∼8% lower for seated versus standing dumbbells (P=0.070); For medial deltoid, ∼7% lower for standing barbell versus dumbbells (P=0.050), ∼7% lower for seated versus standing barbell (P=0.062), 15% lower for seated versus standing dumbbell (P=0.008); For posterior deltoid: ∼25% lower for seated versus standing barbell (P<0.001), ∼24% lower for seated versus standing dumbbells (P=0.002); For biceps, ∼33% greater for seated barbell versus dumbbells (P=0.002), 16% greater for standing barbell versus dumbbell (P=0.074), ∼23% lower for seated versus standing dumbbells (P<0.001); For triceps, ∼39% greater for standing barbell versus dumbbells (P<0.001), ∼20% lower for seated versus standing barbell (P=0.094). 1-RM strength for standing dumbbells was ∼7% lower than standing barbell (P=0.002) and ∼10% lower than seated dumbbells (P<0.001). In conclusion, the exercise with the greatest stability requirement (standing and dumbbells) demonstrated the highest neuromuscular activity of the deltoid muscles, although this was the exercise with the lowest 1-RM strength.
... Many authors have examined the activation of the upper limb muscles during the overhead press [3,[6][7][8][9][10][11][12][13][14]. This activation was presented according to the position of the body during pressing (sitting or standing) [10], surface stability (exercise bench or Swiss ball) [11], grip (narrow or wide) [12][13][14] and movement direction (behind or forward from the head) [3,14]. ...
... Many authors have examined the activation of the upper limb muscles during the overhead press [3,[6][7][8][9][10][11][12][13][14]. This activation was presented according to the position of the body during pressing (sitting or standing) [10], surface stability (exercise bench or Swiss ball) [11], grip (narrow or wide) [12][13][14] and movement direction (behind or forward from the head) [3,14]. In addition, it is possible to find papers in which the authors analyze muscle activity depending on the type of equipment pressed: barbell vs. dumbbells [10,11], dumbbells vs. kettlebells [8], as well as the influence of exercise intensity on muscle activation [7,9]. ...
... This activation was presented according to the position of the body during pressing (sitting or standing) [10], surface stability (exercise bench or Swiss ball) [11], grip (narrow or wide) [12][13][14] and movement direction (behind or forward from the head) [3,14]. In addition, it is possible to find papers in which the authors analyze muscle activity depending on the type of equipment pressed: barbell vs. dumbbells [10,11], dumbbells vs. kettlebells [8], as well as the influence of exercise intensity on muscle activation [7,9]. ...
The overhead press is a multi-joint exercise that has the potential to use a high external load due to the cooperation of many muscle groups. The purpose of this study was to compare the activity of shoulder and back muscles during the overhead press with a kettlebell and a dumbbell. Surface electromyography (EMG) for the anterior and posterior deltoid, upper and lower trapezius, serratus anterior, and spinal erectors was analysed for 20 subjects. Participants performed the four trials of pressing kettlebell and dumbbell, weighted at 6 kg, and 70% of one maximum repetition (1RM) in the sitting position. Statistical analysis was performed using a non-parametric Friedman test and a post-hoc test of Dunn Bonferroni. No significant differences were found in the activation of assessed muscles when comparing dumbbell to kettlebell press trials with the same load (6 kg and 70% of 1RM). However, muscle activity of all muscles except the upper trapezius was always higher for kettlebell pressing. Different center of gravity locations in the kettlebell versus the dumbbell can increase shoulder muscle activity during the overhead press. However, more studies are required to confirm these results.
... When the purpose is to stimulate the muscles surrounding the shoulders, overhead press is one of the most used multi-joint exercises (Ichihashi et al., 2014;McKean and Burkett, 2015;Williams et al., 2020). Particularly, the simultaneous scapular upward rotation (Ichihashi et al., 2014), together with the humerus abduction and elbow extension (Paoli et al., 2010;Saeterbakken and Fimland, 2013) makes the overhead press suitable to stimulate upper trapezius, deltoids and triceps brachii. ...
... When performing overhead press with a barbell, the barbell can pass in front or behind the head, resulting in front (front-BMP) or back barbell military press (back-BMP). While a number of studies have examined the muscles excitation during front-BMP (Kohler et al., 2010;Saeterbakken and Fimland, 2013;Williams et al., 2020), no information are currently available on the muscles excitation during back-BMP, and a direct comparison is consequently not even available. This might derive from a possible fear to perform back-BMP, maybe related to the "high-five" position that might be associated with a greater prevalence anterior shoulder instability in amateurs, albeit these results are not conclusive and should be interpreted with caution (Kolber et al., 2013). ...
... Although no previous study has directly compared the present overhead press variations, previous papers examined the muscle excitation when different level of stabilization was required. For example, in line with the present results, posterior deltoid was more excited when shoulder press was performed standing vs. seated, irrespectively if performed with barbell or dumbbells (Saeterbakken and Fimland, 2013), or barbell vs. machine exercises (McCaw and Friday, 1994;Schwanbeck et al., 2009). A similar pattern was observed here for medial deltoid, so that less stable trajectories require more excitation. ...
Overhead press is commonly performed to reinforce the muscles surrounding the shoulders. However, many overhead press variations can be executed, thus varying the stimuli to each muscle. Therefore, the current study compared the muscles excitation during overhead press performed with the barbell passing in front or behind the head or using a shoulder press machine. Eight competitive bodybuilders performed in random order front (front-BMP) or back barbell military press (back-BMP), and front (front-MSP) with neutral handgrip or back machine shoulder press (back-MSP). Normalized surface electromyographic root mean square (RMS) of anterior, medial and posterior deltoid, upper trapezius, pectoralis major and triceps brachii was recorded during both the ascending and descending phases. During the ascending phase, anterior deltoid showed greater RMS in back-BMP than back-MSP [ES: 1.42, (95% confidence interval 0.32/2.51)]. Medial deltoid showed greater RMS in back-BMP than front-BMP [ES: 3.68 (2.07/5.29)], and back-MSP [ES: 7.51 (4.73/10.29)]. Posterior deltoid showed greater RMS in back-BMP than front-BMP [ES: 9.00 (5.73/12.27)]. Pectoralis major showed greater RMS in front-BMP than back-BMP [ES: 3.11 (1.65–4.56)] and in front-MSP than back-MSP [ES: 20.52 (13.34/27.70)]. During the descending phase, anterior deltoid was more excited in back-BMP compared to front-BMP [ES: 7.66 (4.83/10.49). Medial deltoid showed greater RMS in back-BMP than front-BMP [ES: 4.56 (2.70/6.42)]. Posterior deltoid showed greater RMS in back-BMP than front-BMP [ES: 8.65 (5.50/11.80)]. Pectoralis major showed greater RMS in front-BMP than back-BMP [ES: 4.20 (2.44/5.95)]. No between-exercise difference was observed for upper trapezius. Performing back overhead press enhances the excitation of medial and posterior and partly anterior deltoid, while front overhead favors pectoralis major. Overhead press performed using barbell excites muscles more than using machine to stabilize the trajectory of the external load. Different variations of overhead press appear to provide different stimuli to the shoulder muscles and may be used accordingly during the training routine.
... dumbbell press), with both modalities proving effective for stimulating strength and hypertrophy. However, due to lower stability requirements, heavier weights can be lifted with a barbell than with dumbbells [39,40]. In a cross-over study by Saeterbakken et al. [40], resistance-trained participants were able to perform a 1RM lift with approximately 20% heavier loads during the barbell bench press compared to the dumbbell bench press. ...
... The lower triceps activation during dumbbell presses are likely due to the dumbbells not being connected to each other, and thus the triceps have a reduced capacity to actively contribute to the pushing movement. This was also shown for barbell vs. dumbbell shoulder presses [39]. When synthesizing the body of literature, training with a barbell allows for a higher total muscle activation and an ability to lift heavier weights compared to dumbbells. ...
... The ACSM, as well as an updated review from 2018 by Suchomel et al., recommends performing both variations, but emphasizing bilateral exercises [1,41]. Some authors have noted that unilateral exercises provide the benefit of higher core-activation due to greater stability requirements [39,45]. It should be noted that there is limited evidence on the difference between unilateral and bilateral training. ...
Lack of time is among the more commonly reported barriers for abstention from exercise programs. The aim of this review was to determine how strength training can be most effectively carried out in a time-efficient manner by critically evaluating research on acute training variables, advanced training techniques, and the need for warm-up and stretching. When programming strength training for optimum time-efficiency we recommend prioritizing bilateral, multi-joint exercises that include full dynamic movements (i.e. both eccentric and concentric muscle actions), and to perform a minimum of one leg pressing exercise (e.g. squats), one upper-body pulling exercise (e.g. pull-up) and one upper-body pushing exercise (e.g. bench press). Exercises can be performed with machines and/or free weights based on training goals, availability, and personal preferences. Weekly training volume is more important than training frequency and we recommend performing a minimum of 4 weekly sets per muscle group using a 6–15 RM loading range (15–40 repetitions can be used if training is performed to volitional failure). Advanced training techniques, such as supersets, drop sets and rest-pause training roughly halves training time compared to traditional training, while maintaining training volume. However, these methods are probably better at inducing hypertrophy than muscular strength, and more research is needed on longitudinal training effects. Finally, we advise restricting the warm-up to exercise-specific warm-ups, and only prioritize stretching if the goal of training is to increase flexibility. This review shows how acute training variables can be manipulated, and how specific training techniques can be used to optimize the training response: time ratio in regard to improvements in strength and hypertrophy.
Graphic Abstract
... The technique of the standing press has been well described elsewhere [64,66,67]. The standing press has been extensively used in strength training and rehabilitation programs [53,89,90]. To our knowledge there are no data on power development during standing press to date, although this may be due to its common use for strength and hypertrophy rather than power development. ...
... O'Shea [70] and a more recent review by Bishop et al. [68] have emphasised the importance of WOPDs and especially the push press as an alternative for strength and conditioning programmes. WOPDs derivatives require the ability to develop force through the kinetic chain from the lower to the upper extremities, which may be a powerful stimulus to strengthen muscles of the upper and lower body while optimising motor control and coordination, due to the key role of the trunk and lower body muscles in stabilising and transmitting forces in a closed kinetic chain [53,90,103,106]. Specifically, the push press was compared with the well-studied bench press, suggesting that WOPDs such as push press or jerk and variations are more applicable to explosive events and sports than the bench press due to the technical challenges requiring speed, acceleration, timing and coordination [68][69][70]. ...
... In summary, it may be useful to strategically use the performance parameters and progression according to technical complexity. Firstly, the usual process starts from the development of the slowest and least complex exercise, such as the standing press (non-ballistic nature) to form the basis of upper body strength, shoulder and thoracic complex mobility and overall motor control [53,54,64,90,103], to progress to more difficult and whole body strength-speed demanding exercises such as the push press, push jerk and split jerk (ballistic nature) [45,53,54,68]. An adequate technicalcomplexity progression should follow that order. ...
This review examines the literature on weightlifting overhead pressing derivatives (WOPDs) and provides information regarding historical, technical, kinetic and kinematic mechanisms as well as potential benefits and guidelines to implement the use of WOPDs as training tools for sports populations. Only 13 articles were found in a search of electronic databases, which was employed to gather empirical evidence to provide an insight into the kinetic and kinematic mechanisms underpinning WOPDs. Practitioners may implement WOPDs such as push press, push jerk or split jerk from the back as well as the front rack position to provide an adequate stimulus to improve not only weightlifting performance but also sports performance as: (1) the use of WOPDs is an additional strategy to improve weightlifting performance; (2) WOPDs require the ability to develop high forces rapidly by an impulsive triple extension of the hips, knees and ankles, which is mechanically similar to many sporting tasks; (3) WOPDs may be beneficial for enhancing power development and maximal strength in the sport population; and, finally, (4) WOPDs may provide a variation in training stimulus for the sports population due to the technical demands, need for balance and coordination. The potential benefits highlighted in the literature provide a justification for the implementation of WOPDs in sports training. However, there is a lack of information regarding the longitudinal training effects that may result from implementing WOPDs.
... 710 studies have examined the effect of changes in stability during common resistance training exercises. These studies have examined different resistance implements (2,5,(10)(11)(12)16), body positions (13), and surfaces (1,4,5,7,14,15), or a combination of these variables. One of the specific exercises that has been examined is the overhead press (5,13,15). ...
... One of the specific exercises that has been examined is the overhead press (5,13,15). Saeterbakken and Fimland examined the anterior, middle, and posterior deltoid during an overhead press (13). The authors compared the barbell and dumbbell overhead press when seated and standing. ...
... As noted by Saeterbakken and Fimland, previous research has reported inconsistent EMG results when comparing exercises with differing levels of stability (13). However, these differences may be better understood through a clear comparison of the purpose of these studies. ...
International Journal of Exercise Science 11(1): 708-716, 2018. Kettlebells often replace dumbbells during common resistance training exercises such as the overhead press. When performing an overhead press, the center of mass of a dumbbell is in line with the glenohumeral joint. In comparison, the center of mass of the kettlebell is posterior to the glenohumeral joint. Posterior displacement of the kettlebell center of mass may result in less stability during the pressing motion. The purpose of this study was to examine muscle activity during an overhead press with resistance training implements of differing stability. Surface electromyography (EMG) for the anterior deltoid and pectoralis major was analyzed for 21 subjects. Technique and pace of the overhead press were standardized and monitored. Filtered EMG data were collected, normalized, and average peak amplitude as a percentage of MVIC was calculated for each repetition. A repeated-measures analysis of variance was used to compare EMG values for the anterior deltoid and pectoralis major across implements. A statistically significant increase in normalized EMG activity (p < .05) was identified in the anterior deltoid when using the dumbbell (63.3±13.3%) compared to the kettlebell (57.9±15.0%). In this study, EMG activity was augmented in the anterior deltoid when using the more stable implement, the dumbbell.
... The muscles involved in overhead pressing movements comprise a significant portion of the trunk and upper extremities, with contributions provided from the lower body during the standing variations (14). Instructional content from Waller et al. state that as load increases in the standing barbell press, isometric activity from the lower extremities must increase as well (19). ...
... This suggests, on average, females encounter more instability in the spine and torso when lifting heavy loads overhead not only leading to compromised performance but potential injury as well. Incorporation of specific trunk and scapular stability exercises can also aid in preventing injury to the glenohumeral joint when used in conjunction with pressing movements (2,13,14,17). ...
... Although few studies have been conducted on pressing movements compared with other resistance training movements, some research has explored the correlation between performing resistance training on an unstable surface and with enhanced muscle activity. Saeterbakken and Fimland concluded that an overhead press performed with a barbell on a stable surface showed significantly higher electromyography data when compared with an overhead barbell press performed on an unstable surface (14). This suggests athletes and coaches can be encouraged in the efficacy and effectiveness of the SBOHP in traditional training environments when compared with training methods that may be more complex, esoteric, and expensive (i.e., the use of unstable lifting surfaces). ...
The purpose of this column is to explore the standing barbell overhead press (sbohp) in terms of its execution, musculature involved, potential benefits, practical applications, and its evolution. the sbohp is among the most elementary tests of upper body and overhead strength. because of its removal as a contested barbell lift, general emphasis on the movement has declined slightly, but it is still widely implemented in a plethora of settings from recreational and professional sports performance to utility in rehabilitation.
... Yet, the prescription of the dip in these various performance and rehabilitation programs is based on the practitioner's experience rather than empirical evidence. While other upper-body push exercises, that may have similar neuromechanical profiles, have previously been investigated, including the push-up [11][12][13], bench press [14], and shoulder press [15][16][17], such research has not been conducted on dip variations, and so the neuromechanical profile of these exercises remains unknown. The dip is often prescribed in a wide range of exercise contexts, from increasing sports performance in experienced athletes [1][2][3], to athletes rehabilitating from shoulder instability [4] or other upper extremity injuries [5,6]. ...
... Yet, the prescription of the dip in these various performance and rehabilitation programs is based on the practitioner's experience rather than empirical evidence. While other upper-body push exercises, that may have similar neuromechanical profiles, have previously been investigated, including the push-up [11][12][13], bench press [14], and shoulder press [15][16][17], such research has not been conducted In addition to the lack of evidence justifying the dips use in exercise programs, the dip has also been criticised as a potentially high-risk exercise for injury to the shoulder [2,7,18]. A potential mechanism of injury has been suggested by McKenzie, Crowley-McHattan [18] relating to injury of anterior shoulder and PM. ...
The purpose of this study was to profile and compare the kinematics, using 3D motion capture, and muscle activation patterns, using surface electromyography (sEMG), of three common dip variations; the bench, bar, and ring dips. Thirteen experienced males performed four repetitions of each dip variation. For each participant, repetitions 2–4 were time-normalized and then averaged to produce a mean value for all kinematic and sEMG variables. The mean maximal joint angles and mean peak sEMG amplitudes were compared between each variation using a one-way ANOVA with repeated measures. Several significant differences (p < 0.05) between dip variations were observed in both kinematic and sEMG data. The bench dip predominantly targets the triceps brachii but requires greater shoulder extension range. The mean peak triceps brachii activation was 0.83 ± 0.34 mV on the bench, 1.04 ± 0.27 mV on the bar, and 1.05 ± 0.40 mV on the ring. The bar dip is an appropriate progression from the bench dip due to the higher peak muscle activations. The ring dip had similar peak activations to the bar dip, with three muscles increasing their activation intensities further. These findings have implications for practitioners prescribing the dip, particularly to exercisers with a history of shoulder pain and injury.
... Before testing, the participants were explained how to use the Borg CR10 scale (Saeterbakken and Fimland, 2013). Immediately after performing 10-RM, the participants were asked to rate their perceived exertion. ...
... However, it is also possible that the different postures contributed to these effects, as participants were lying on a bench when the Brought to you by | NTNU University Library Authenticated Download Date | 4/26/18 10:52 AM Journal of Human Kinetics -volume 61/2018 http://www.johk.pl exercises with dumbbells were performed, but standing during execution with elastic bands, which is another way of inducing higher instability and to increase muscle activation of the deltoideus anterior (Saeterbakken and Fimland, 2013) The increased stability requirement possibly induced by a standing posture, involving more stabilizing muscles, could also explain why higher ratings of perceived effort on the Borg CR10 scale were reported for elastic bands compared to dumbbells. Partly in agreement with our finding, Jakobsen and coworkers found a higher rating of perceived effort when performing knee flexions with elastic bands versus a conventional training machine . ...
Elastic resistance bands require little space, are light and portable, but their efficacy has not yet been established for several resistance exercises. The main objective of this study was to compare the muscle activation levels induced by elastic resistance bands versus conventional resistance training equipment (dumbbells) in the upper-body resistance exercises flyes and reverse flyes. The level of muscle activation was measured with surface electromyography in 29 men and women in a cross-over design where resistance loadings with elastic resistance bands and dumbbells were matched using 10-repetition maximum loadings. Elastic resistance bands induced slightly lower muscle activity in the muscles most people aim to activate during flyes and reverse flies, namely pectoralis major and deltoideus posterior, respectively. However, elastic resistance bands increased the muscle activation level substantially in perceived ancillary muscles, that is deltoideus anterior in flyes, and deltoideus medius and trapezius descendens in reverse flyes, possibly due to elastic bands being a more unstable resistance modality. Overall, the results show that elastic resistance bands can be considered a feasible alternative to dumbbells in flyes and reverse flyes.
... Before testing, the participants were explained how to use the Borg CR10 scale (Saeterbakken and Fimland, 2013). Immediately after performing 10-RM, the participants were asked to rate their perceived exertion. ...
... Increased stability requirement could possibly elicit higher neural drive to stabilize the shoulder joint, which had been suggested previously for dumbbells versus the barbell chest press (Saeterbakken et al., 2011). However, it is also possible that the different postures contributed to these effects, as participants were lying on a bench when the exercises with dumbbells were performed, but standing during execution with elastic bands, which is another way of inducing higher instability and to increase muscle activation of the deltoideus anterior (Saeterbakken and Fimland, 2013) The increased stability requirement possibly induced by a standing posture, involving more stabilizing muscles, could also explain why higher ratings of perceived effort on the Borg CR10 scale were reported for elastic bands compared to dumbbells. Partly in agreement with our finding, Jakobsen and coworkers found a higher rating of perceived effort when performing knee flexions with elastic bands versus a conventional training machine . ...
Elastic resistance bands require little space, are light and portable, but their efficacy has not yet been established for several resistance exercises. The main objective of this study was to compare the muscle activation levels induced by elastic resistance bands versus conventional resistance training equipment (dumbbells) in the upper-body resistance exercises flyes and reverse flyes. The level of muscle activation was measured with surface electromyography in 29 men and women in a cross-over design where resistance loadings with elastic resistance bands and dumbbells were matched using 10-repetition maximum loadings. Elastic resistance bands induced slightly lower muscle activity in the muscles most people aim to activate during flyes and reverse flies, namely pectoralis major and deltoideus posterior, respectively. However, elastic resistance bands increased the muscle activation level substantially in perceived ancillary muscles, that is deltoideus anterior in flyes, and deltoideus medius and trapezius descendens in reverse flyes, possibly due to elastic bands being a more unstable resistance modality. Overall, the results show that elastic resistance bands can be considered a feasible alternative to dumbbells in flyes and reverse flyes.
... Because of the increased control the athlete has with dumbbells, Durall et al. (11) recommended using them as a potential alternative even in a relatively higher risk exercise such as the incline press. Evidence suggests that using dumbbells instead of barbells may require individuals to control and balance the weights independently and potentially alter the involvement of the agonists, synergists, stabilizers, and antagonists (39). Both Welsch et al. (48) and Saeterbakken et al. (40) reported similar electromyographic (EMG) activity in the pectoralis major and anterior deltoid in dumbbell chest presses compared with barbell although dumbbell loads were 63-83% of the barbell loads. ...
... Similar to the chest press, the use of dumbbells offers the advantage of more freedom to find a pain-free range of motion. Furthermore, Saeterbakken and Fimland (39) reported increased neuromuscular activity in the deltoid muscle using dumbbells over barbells in the shoulder press despite the dumbbell shoulder press having a lower 1 repetition maximum strength value as compared with the barbell shoulder press. ...
This article provides a summary of the literature related to shoulder pain in strength athletes. The prevalence of shoulder injuries and types of shoulder injuries sustained will be reviewed. Exercises that may predispose strength athletes to shoulder injuries and suggestions of specific exercise modifications to reduce the risk of injury will be discussed. Finally, preventive strategies to reduce the likelihood of shoulder injuries will be addressed. For a video abstract describing this issue, see video, supplemental digital content 1, http://links.lww.com/SCJ/A199.
... 5 Strength training can be performed with many different types of equipment. In the literature, a broad array of exercise comparisons exist, including free weights versus fixed movement patterns, 13,14 dumbbells versus barbells, 15 cable pulleys versus variable resistance, 16 vibration training versus conventional training, 17 as well as the effect of more or less stability requirements. 15,18 Previous studies using electromyography have shown a high degree of muscle activity in the leg muscles using conventional training machines in healthy young subjects, 19 elderly postoperative subjects, 20 and patients with chronic stroke. ...
... In the literature, a broad array of exercise comparisons exist, including free weights versus fixed movement patterns, 13,14 dumbbells versus barbells, 15 cable pulleys versus variable resistance, 16 vibration training versus conventional training, 17 as well as the effect of more or less stability requirements. 15,18 Previous studies using electromyography have shown a high degree of muscle activity in the leg muscles using conventional training machines in healthy young subjects, 19 elderly postoperative subjects, 20 and patients with chronic stroke. 8,21 However, facilities with conventional machine exercises are often expensive, and not all physical therapists may be able to offer their patients this type of training. ...
Objective:
To investigate whether elastic resistance training can induce comparable levels of muscle activity as conventional machine training in chronic stroke patients.
Design:
Comparative study SETTING: Outpatient rehabilitation facility PARTICIPANTS: 18 stroke patients with hemiparesis (mean age 57 (SD: 8) years).
Interventions:
Patients performed 3 consecutive reps at 10 repetition maximum (RM) of unilateral knee extension- and flexion, using elastic resistance and conventional training machines.
Main outcome measure:
Surface electromyography (EMG) was measured in vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF) and semitendinosus (ST), and normalized to the maximal EMG (nEMG) of the non-paretic leg.
Results:
In the paretic leg, agonist muscle activity ranged from 18-24% nEMG during knee flexion and 32-40% nEMG during knee extension. For the latter, VL nEMG was higher during machine exercise compared with elastic resistance (40% [95% CI 33 - 47] vs 32% [95% CI 25 - 39], P=0.003). In the non-paretic leg, agonist muscle activity ranged from 54-61% during knee flexion and 52-68% during knee extension (n.s.). For knee flexion, ST nEMG was higher (61% [95% CI 50 - 71] vs 54% [95% CI 44 - 64], P=0.016), and for knee extension VM nEMG was higher (68% [95% CI 60 - 76] vs 56% [95% CI 48 - 64], P<0.001) during machine exercise compared with elastic resistance. By contrast, antagonist co-activation was significantly higher during knee flexion with elastic resistance compared with the machine. Lastly, there were no differences in perceived exertion between exercise modalities.
Conclusion:
Machine training appears to induce slightly higher levels of muscle activity in some of the investigated muscles compared to elastic resistance during lower-limb strength training in chronic stroke patients. The higher level of co-activation during knee flexions with elastic tubing suggests that elastic resistance exercises are more difficult to perform. This is likely due to a higher level of movement instability.
... Bipolar silver chloride surface electrodes (AE-131 NeuroDyne Medical, Cambridge, MA, USA) with 11-mm contact diameter and 2.0 cm center-to-center distance were placed over the center of the muscle belly along the principal direction of the muscle fibers of the pectoralis major (sternocostal and clavicular part), anterior deltoid, medial deltoid, posterior deltoid, triceps brachii (long head), biceps brachii, and latissimus dorsi. The procedures and placement were performed in accordance with the recommendations of SENIAM [33] and previous studies [4,15,34,35]. The electrodes for pectoralis major were placed 4 cm medial to the axillary fold with the sternocostal part approximately 4 cm above the clavicular part. ...
Background: This study compared the muscle activity and six repetition maximum (6-
RM) loads in bench press with narrow, medium, and wide grip widths with sub-group comparisons of resistance-trained (RT) and novice-trained (NT) men. Methods: After two familiarization sessions, twenty-eight subjects lifted their 6-RM loads with the different grip widths with measurement of electromyographic activity. Results: Biceps brachii activity increased with increasing grip width, whereas wide grip displayed lower triceps brachii activation than medium and narrow. In the anterior deltoid, greater activity was observed using a medium compared to narrow grip. Similar muscle activities were observed between the grip widths for the other muscles. For the RT group, greater biceps brachii activity with increasing grip width was observed, but only greater activity was observed in the NT group between narrow and wide. Comparing wide and medium grip width, the RT group showed lower triceps activation using a wide grip, whereas the NT group showed lower anterior deltoid activation using a narrow compared to medium grip. Both groups demonstrated lower 6-RM loads using a narrow grip compared to the other grips. Conclusion: Grip
widths affect both 6-RM loads and triceps brachii, biceps brachii, and anterior deltoid activity especially between wide and narrow grip widths.
... kg) caused the higher activity of the vastus lateralis (Lawrence et al., 2018). However, since the relative loads used in the two exercises were identical, the load should not affect the outcome (Andersen et al., 2014;Saeterbakken and Fimland, 2013). Alternatively, since the exercises were performed unilaterally, a higher EMG amplitude of the vastus lateralis could have been produced to stabilize the knee joint while performing the leg press. ...
Resistance-training exercises can be classified as either single-or multi-joint exercises and differences in surface electromyography (EMG) amplitude between the two training methods may identify which muscles can benefit from either training modality. This study aimed to compare the surface EMG amplitude of five hip-and knee extensors during one multi-joint (leg press) and two single joint exercises (knee extension and kickback). Fifteen resistance trained men completed one familiarization session to determine their unilateral six repetitions maximum (6RM) in the three exercises. During the following experimental session, EMG amplitudes of the vastus lateralis, vastus medialis, rectus femoris, gluteus maximus and biceps femoris of the left leg were measured while performing three repetitions on their respective 6RM loads. The multi-joint exercise leg press produced higher EMG amplitude of the vastus lateralis (ES = 0.92, p = 0.003) than the single-joint exercise knee extension, whereas the rectus femoris demonstrated higher EMG amplitude during the knee extension (ES = 0.93, p = 0.005). The biceps femoris EMG amplitude was higher during the single-joint exercise kickback compared to the leg press (ES = 2.27, p < 0.001), while no significant differences in gluteus maximus (ES = 0.08, p = 0.898) or vastus medialis (ES = 0.056, p = 0.025 were observed between exercises. The difference in EMG amplitude between single-and multi-joint exercises appears to vary depending on the specific exercises and the muscle groups tested. Leg press is a viable and time-efficient option for targeting several hip-and knee extensors during resistance training of the lower limbs, but the single-joint exercises may be preferable for targeting the rectus femoris and biceps femoris.
... The use of different exercises with different mechanical strains has been highly recommended for the complete development of different deltoid portions. In this sense, priority exercises such as the bench press (McCaw and Friday, 1994;Schick et al., 2010;Welsch et al., 2005;Wilk et al., 2019), lat pulldown (Andersen et al., 2014;Vilaça-Alves et al., 2014), seated row (Botton et al., 2013;Franke et al., 2015), and complementary exercises such as the lateral raise (Botton et al., 2013), shoulder press (Saeterbakken and Fimland, 2013), and reverse pec deck fly (Botton et al., 2013;Franke et al., 2015) can be used. However, the importance of including complementary exercises in ST routines, as well as how these different exercises affect the muscle recruitment of the deltoid portions remain still unclear. ...
The aims of this study were to compare muscle activity of the anterior deltoid, medial deltoid, and posterior deltoid in the bench press, dumbbell fly, shoulder press, and lateral raise exercises. Thirteen men experienced in strength training volunteered for the study. Muscle activation was recorded during maximum isometric voluntary contraction (MVIC) for data normalization, and during one set of 12 repetitions with the load of 60% 1RM in all exercises proposed. One-way repeated-measures ANOVA with Bonferroni's posthoc was applied using a 5% significance level. For anterior deltoid, the shoulder press (33.3% MVIC) presented a significantly higher level of activation when compared to other exercises. Also, no significant difference was found between the bench press (21.4% MVIC), lateral raise (21.2% MVIC), and dumbbell fly (18.8% MVIC). For the medial deltoid, the lateral raise (30.3% MVIC) and shoulder press (27.9% MVIC) presented a significantly higher level of activity than the bench press (5% MVIC) and dumbbell fly (3.4% MVIC). Besides, no significant difference was found between the bench press and the dumbbell fly. For the posterior deltoid, the lateral raise (24% MVIC) presented a significantly higher level of activation when compared to other exercises. For the posterior deltoid portion, the shoulder press (11.4% MVIC) was significantly more active than the bench press (3.5% MVIC) and dumbbell fly (2.5% MVIC). Moreover, no significant difference was found between the bench press and the dumbbell fly. In conclusion, the shoulder press and lateral raise exercises showed a higher level of muscle activation in the anterior deltoid and medial deltoid when compared to the bench press and dumbbell fly exercises.
... dumbbell flies, incline bench press) or use exercise machines in their training routines. Recently, coaches and athletes have included instability within resistance training to strengthen stabilizing muscles and increase stability in the shoulder girdle [1,2]. Improved joint stability may have advantages when generating force during more stable conditions [3][4][5]. ...
The aim of the study was to compare the EMG amplitude in bench press (stable loads) to bench press using loads moving in anteroposterior and mediolateral directions. Seventeen resistance-trained men, with 9.4±4.7 years of resistance training experience were recruited. After a familiarization session assessing 1 repetition maximum (RM) in the bench press, participants performed: 1) bench press with traditional stable loading 2) bench press with loads (2x5kg) attached as pendulums swinging forward/backwards and 3) left/right in randomized order. The total load was 70% of the 1RM load. Electromyography was measured in the pec-toralis major, anterior-and posterior deltoid, biceps brachii, triceps brachii and external obli-ques. Using stable loads, the pectoralis major demonstrated lower EMG amplitude compared to the two unstable conditions. In the external obliques, the stable conditions demonstrated lower EMG amplitude than the swing in the mediolateral direction, but not the anteroposterior direction. There were no differences between two swinging loads or the three conditions for the triceps brachii, biceps brachii, anterior deltoid or posterior deltoid. In conclusion, swinging in bench press resulted in similar EMG amplitude in the shoulder-and arm muscles, but greater pectoralis and external oblique (only mediolateral swing) activity compared to bench press.
... The mean RMS EMG value of all six repetitions in each condition was used for further analysis. Additionally, the fifth repetition was divided into upper, middle, and lower phases of the descending and ascending part (total of six phases) (Saeterbakken and Fimland, 2012;2013a). These phases were classified by splitting the range of motion into three identical lengths. ...
The purpose of the study was to compare the muscle activity in the prime movers and antagonist between the barbell bench press (BBP) and the dumbbell flyes (DF) Seventeen resistance-trained men (age 22.9 ± 1.8 yrs; height 1.80 ± 0.06 m; body mass 80.0 ± 8.3 kg), with 4.8 ± 2.0 years resistance training experience, completed the study. The surface electromyographic activation was measured in four different muscles (pectoralis major, anterior del-toids, triceps brachii, and biceps brachii) during six repetition maximum loads in both exercises. To better understand eventual differences, an in-depth analysis of the fifth repetition was performed , dividing it into six phases (lower, middle, and upper phase of the descending and ascending movement). The results showed a higher muscle activation in the whole movement and the majority of the lifting phases for pectoralis major, deltoids anterior , and triceps brachii for the BBP compared to the DF (8-81 %, p ≤ 0.05). However, the antagonist biceps brachii showed a higher muscle activation (57-86 %, p ≤ 0.05) in the DF compared to the BBP. In conclusion, both exercises could be included in training programs, but the BBP should be emphasized because of the higher muscle activation overall. Among specific populations, were tasks based on strength and control in a horizontal shoulder flexion position with extended elbows often occurs, the DF might prove useful.
... The inclusion of highly experienced bench press athletes may also explain the similar anterior deltoid activation between sides and conditions. In comparison, increased stability requirement has demonstrated increased deltoid poster activation in shoulder press (Saeterbakken and Fimland 2013a;Kohler et al. 2010). However, the stability requirement may not significantly alter the posterior part of the shoulder muscle when performing asymmetric lifting which also resulted in similar muscle activation. ...
PurposeTo determine the effects of asymmetric loads on muscle activity with the bench press.Method
Seventeen resistance-trained men performed one familiarization session including testing one repetition maximum (1RM) and three 5 repetition maximum (RM) lifts; using symmetric loads, 5% asymmetric loads, and 10% asymmetric loads. The asymmetric loading (i.e., reduced load on one side) was calculated as 5% and 10% of the subject`s 1RM load. In the experimental session, the three conditions of 5RM were conducted with electromyographic activity from the pectoralis major, triceps brachii, biceps brachii, anterior deltoid, posterior deltoid, and external oblique on both sides of the body.ResultsOn the loaded side, asymmetric loads reduced triceps brachii activation compared to symmetric loads, whereas the other muscles demonstrated similar muscle activity between the three conditions. On the de-loaded side, 10% asymmetry in loading resulted in lower pectoralis major, anterior deltoid, and biceps brachii activation compared to 5% asymmetric and symmetric loading. On the de-loaded side, only pectoralis major demonstrated lower muscle activation than symmetric loads. Furthermore, asymmetric loads increased external oblique activation on both sides compared to symmetric loads.Conclusions
Asymmetric bench press loads reduced chest and shoulder muscle activity on the de-loaded side while maintaining the muscle activity for the loaded side. The authors recommend resistance-trained participants struggling with strength imbalances between sides, or activities require asymmetric force generation (i.e., alpine skiing or martial arts), to implement asymmetric training as a supplement to the traditional resistance training.
... The use of different exercises with different mechanical strains has been highly recommended for the complete development of different deltoid portions. In this sense, priority exercises such as the bench press (McCaw and Friday, 1994;Schick et al., 2010;Welsch et al., 2005;Wilk et al., 2019), lat pulldown (Andersen et al., 2014;Vilaça-Alves et al., 2014), seated row (Botton et al., 2013;Franke et al., 2015), and complementary exercises such as the lateral raise (Botton et al., 2013), shoulder press (Saeterbakken and Fimland, 2013), and reverse pec deck fly (Botton et al., 2013;Franke et al., 2015) can be used. However, the importance of including complementary exercises in ST routines, as well as how these different exercises affect the muscle recruitment of the deltoid portions remain still unclear. ...
The aims of this study were to compare muscle activity of the anterior deltoid, medial deltoid, and posterior deltoid in the bench press, dumbbell fly, shoulder press, and lateral raise exercises. Thirteen men experienced in strength training volunteered for the study. Muscle activation was recorded during maximum isometric voluntary contraction (MVIC) for data normalization, and during one set of 12 repetitions with the load of 60% 1RM in all exercises proposed. One-way repeated-measures ANOVA with Bonferroni's posthoc was applied using a 5% significance level. For anterior deltoid, the shoulder press (33.3% MVIC) presented a significantly higher level of activation when compared to other exercises. Also, no significant difference was found between the bench press (21.4% MVIC), lateral raise (21.2% MVIC), and dumbbell fly (18.8% MVIC). For the medial deltoid, the lateral raise (30.3% MVIC) and shoulder press (27.9% MVIC) presented a significantly higher level of activity than the bench press (5% MVIC) and dumbbell fly (3.4% MVIC). Besides, no significant difference was found between the bench press and the dumbbell fly. For the posterior deltoid, the lateral raise (24% MVIC) presented a significantly higher level of activation when compared to other exercises. For the posterior deltoid portion, the shoulder press (11.4% MVIC) was significantly more active than the bench press (3.5% MVIC) and dumbbell fly (2.5% MVIC). Moreover, no significant difference was found between the bench press and the dumbbell fly. In conclusion, the shoulder press and lateral raise exercises showed a higher level of muscle activation in the anterior deltoid and medial deltoid when compared to the bench press and dumbbell fly exercises.
... Resistance training exercise promotes neural and structural modifications [15,16] and combining them with instability can increase the sensory, biomechanical and motor-processing pattern [17]. Furthermore, neuromuscular adaptations like decreased co-contractions and improved coordination have been reported, with a consequential increase in joint stability [16,18,19]. Several authors have investigated the features of instability resistance training, providing evidence that stability alteration during resistance exercise effectively enhanced neuromuscular activity (e.g. ...
Background:
Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass (UWM) affects the muscular activity of the shoulder stabilizers. Aim of the study was to assess neuromuscular activity of dynamic shoulder stabilizers under four conditions of stable and UWM during three shoulder exercises. It was hypothesized that a combined condition of weight with UWM would elicit greater activation due to the increased stabilization demand.
Methods:
Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 s.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different exercise conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root-mean-square values (RMS) were normalized to MVIC (%MVIC). Differences between conditions for RMS%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test; p ≤ 0.05; Bonferroni adjusted α = 0.008).
Results:
PWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p > 0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles.
Conclusion:
Higher weight generated greater muscle activation whereas an UWM raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an UWM increased the RMS%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs.
... This validates previous research involving mechanical work during resistance training verifying anaerobic response (3). Increased neuromuscular activity and muscle recruitment due to the body positioning during the exercise on the FKM could explain the differences as compared to the cycle ergometer (11,13). Further interpretation of these findings indicates that the FKM device may be better suited for anaerobic rather than aerobic exercise training (5, 15). ...
The purpose of this study was to compare the metabolic effects during a similar bout of exercise on a novel, whole body exercise device (Fish and Kangaroo Machine; FKM) and a cycle ergometer. Recreationally active men and women (n =13) completed two exercise sessions. The exercise protocol included intervals alternating between exercise (3-min) and rest (3-min) for a total duration of 39-min. The exercise intensity between the two modes was matched based on heart rate response. Heart rate, cardiac output, and stroke volume were measured using a wireless telemetry technique (Physioflow Enduro). Oxygen consumption (VO2) was measured via breath-by-breath automated analysis of expired respiratory gas (MGC Diagnostics Ultima). Capillary blood lactate was measured using a handheld meter (LactatePlus). While maintaining the heartrate response, stroke volume presented at a higher-level during rest periods, although not significant. There was also higher cardiac output at the end of the exercise bout with the FKM. VO2 was lower at the same heart rate and peak lactate was higher during FKM exercise. Cardiovascular recovery was improved following FKM exercise compared to cycling. The observed responses demonstrated that for a similar heart rate response, the FKM has an enhanced anaerobic metabolic component compared to cycling. These findings demonstrate the FKM may represent a novel exercise device comparable to cycling with unique anaerobic training potential.
... Dumbbells allow more freedom as compare to barbells but it also requires coordination. As compare to barbell, during the last phase of the press, dumbbells allow the arms to come closer that result in greater range of motion 4 . A twisting variation of the overhead dumbbell shoulder press (also known as basic shoulder press) is the Arnold dumbbell press. ...
Objective: To analyze the muscle activation of anterior and medial deltoid muscles while performing two different grip variations of dumbbell shoulder press. Methodology: Ten healthy male participants (age = 20.9 ± 1.449 years, height = 1.71 ± .038 m, weight=69.65 ± 2.92 kg) from Lakshmi Bai National Institute of Physical Education (Gwalior, M.P, India) were recruited as a sample of the study. The participants performed 5 repetitions of two different grip variations of dumbbell shoulder press. The exercises were Arnold Dumbbell Press (ADP) and Overhead Dumbbell Press (ODP). Surface Electromyography (SEMG) was used to record the muscle activation and for measuring muscle electrical activity that occurs during muscle contraction. Results: Paired t–test was used to detect mean differences between the two variations of dumbbell shoulder press. It was found that Anterior and Medial Deltoid muscles were more active while performing ADP (AD-1346.4292.495; MD – 827.5 146.426) as compared to ODP (AD - 1043.4 141.299; MD – 725.4 100.4). Also while performing both the exercises, the muscle activation of anterior deltoid was found to be much higher than Medial Deltoid. Conclusions: Arnold dumbbell press was more effective exercise for the activation of Anterior and Medial deltoid muscles as compared to the Overhead Dumbbell Press. Anterior deltoid acts as primary muscle while performing both the exercises, as the muscle activation is much higher as compared to medial deltoid. © 2017, Indian Journal of Public Health Research and Development. All rights reserved.
... The 2 latter methodological limitations make it difficult to transfer the findings to real life training as intensity usually is prescribed relative to muscular strength in the trained exercise, and people engaged in resistance training usually perform exercises (close) to failure. The importance of using equal relative loads when comparing different exercises is emphasized in several recent original studies (17,15,16,19) and a recent review (5). ...
Andersen, V, Fimland, MS, Wiik, E, Skoglund, A, and Saeterbakken, AH. Effects of grip width on muscle strength and activation in the lat pull-down. J Strength Cond Res 28(4): 1135-1142, 2014-The lat pull-down is one of the most popular compound back exercises. Still, it is a general belief that a wider grip activates the latissimus dorsi more than a narrow one, but without any broad scientific support. The aim of the study was to compare 6 repetition maximum (6RM) load and electromyographic (EMG) activity in the lat pull-down using 3 different pronated grip widths. Fifteen men performed 6RM in the lat pull-down with narrow, medium, and wide grips (1, 1.5, and 2 times the biacromial distance) in a randomized and counterbalanced order. The 6RM strengths with narrow (80.3 ± 7.2 kg) and medium grip (80 ± 7.1 kg) were higher than wide grip (77.3 ± 6.3 kg; p = 0.02). There was similar EMG activation between grip widths for latissimus, trapezius, or infraspinatus, but a tendency for biceps brachii activation to be greater for medium vs. narrow (p = 0.09), when the entire movement was analyzed. Analyzing the concentric phase separately revealed greater biceps brachii activation using the medium vs. narrow grip (p = 0.03). In the eccentric phase, there was greater activation using wide vs. narrow grip for latissimus and infraspinatus (p ≤ 0.04), and tendencies for medium greater than narrow for latissimus, and medium greater than wide for biceps (both p = 0.08), was observed. Collectively, a medium grip may have some minor advantages over small and wide grips; however, athletes and others engaged in resistance training can generally expect similar muscle activation which in turn should result in similar hypertrophy gains with a grip width that is 1-2 times the biacromial distance.
Background
Rupture of the distal biceps is relatively rare and post-operative protocols are typically vague and are used on many patients, regardless of pre-morbid status. The primary objective is to share the progressive loading strategy used in the rehabilitation of a strongman athlete following a surgical repair of the distal biceps. An additional objective is to highlight the need for individualized protocols and progressions with respect to patient goals and sport demands, as well as the need for shared decision making (SDM) between the medical doctor, patient, and rehabilitation provider.
Case Presentation
The subject is a 39-year-old strong man competitor who suffered a distal biceps rupture while doing a tire flip during training. After having it repaired, the post-operative recovery was unremarkable. The focus of the described intervention was establishing load during rehabilitation exercises that were unique to this individual based on his pre-morbid level of strength and training history as well as the unique demands of his sport.
Outcomes
The patient achieved symmetrical isokinetic strength of the elbow flexors at 60°/second in supine at six months post-operative.
Discussion
The case highlights a successful outcome in a strongman competitor with a distal biceps rupture repair. Typically, protocols are vague and lack specific standards for establishment of load for exercises. Often starting points and progressions are arbitrary and lack rationale tailored to individual needs and/or pre-morbid status. The case offers a framework for establishing and progressing load while also discussing how a shared decision-making model can lead to positive outcomes.
O objetivo do presente estudo foi verificar a quantidade de sessões necessárias para determinação da carga máxima em testes múltiplos de uma repetição máxima nos exercícios de força com pesos livres. Dezessete homens (22,5 ± 3,5 anos), não praticantes de musculação há quatro meses, fizeram quatro sessões de teste de 1-RM em cinco exercícios: supino reto, remada curvada,elevação frontal, rosca direta de bíceps e tríceps testa, respectivamente. Para o tratamento dos
dados foi utilizada a ANOVA one way, seguida do teste post hoc de Newman-Keuls, com p<0.05. A estabilização da carga para os exercícios supino reto, rosca direta de bíceps e tríceps testa
ocorreu entre a 3 e 4 sessões de teste. Para os exercícios remada curvada e elevação frontal quatrosessões não foram sufcientes para encontrar uma medida acurada de força máxima. Sugere-se
a realização de três sessões de teste para os exercícios supino horizontal, rosca direta de bíceps e tríceps testa e de pelo menos quatro sessões para os exercícios remada curvada e elevação frontal.
Little is known about the effect of performing common resistance exercises standing compared to seated and unilaterally compared to bilaterally on muscle activation of the core. Thus, the purpose of this study was to compare the electromyographic activity (EMG) of the superficial core muscles (i.e. rectus abdominis, external oblique and erector spinae) between seated, standing, bilateral and unilateral dumbbell shoulder presses. 15 healthy males performed five repetitions at 80% of one-repetition maximum of the exercises in randomized order. Results were analyzed with a two-way analysis of variance and a Bonferroni post hoc test. The position × exercise interaction was significantly different for rectus abdominis (P = 0.016), but not for external oblique (P = 0.100) and erector spinae (P = 0.151). The following EMG results were observed: For rectus abdominis: ~49% lower in seated bilateral versus unilateral (P < 0.001), similar in standing bilateral versus unilateral (P = 0.408), ~81% lower in bilateral seated versus standing (P < 0.001), ~59% lower in unilateral seated versus standing (P < 0.001); For external oblique: ~81% lower in seated bilateral versus unilateral (P < 0.001), ~68% lower in standing bilateral than unilateral (P < 0.001), ~58% lower in bilateral seated versus standing (P < 0.001), ~28% lower in unilateral seated versus standing (P = 0.002); For erector spinae: similar in seated bilateral versus unilateral (P = 0.737), ~18% lower in standing bilateral versus unilateral (P = 0.001), similar in seated versus standing bilateral (P = 0.480) and unilateral (P = 0.690). In conclusion, to enhance neuromuscular activation of the superficial core muscles, standing exercises should be used instead of seated exercises, and unilateral exercises should be used instead of bilateral exercises.
The purpose of this study was to compare one-repetition maximum (1-RM) and muscle activity in three chest-press exercises with different stability requirements (Smith machine, barbell, and dumbbells). Twelve healthy, resistance-trained males (age 22.7 ± 1.7 years, body mass 78.6 ± 7.6 kg, stature 1.80 ± 0.06 m) were tested for 1-RM of the three chest-press exercises in counterbalanced order with 3-5 days of rest between the exercises. One-repetition maximum and electromyographic activity of the pectoralis major, deltoid anterior, biceps, and triceps brachii were recorded in the exercises. The dumbbell load was 14% less than that for the Smith machine (P ≤ 0.001, effect size [ES] = 1.05) and 17% less than that for the barbell (P ≤ 0.001, ES = 1.11). The barbell load was ∼3% higher than that for the Smith machine (P = 0.016, ES = 0.18). Electrical activity in the pectoralis major and anterior deltoid did not differ during the lifts. Electrical activity in the biceps brachii increased with stability requirements (i.e. Smith machine <barbell <dumbbells; P ≤ 0.005; ES = 0.57, 1.46, and 2.00, respectively), while triceps brachii activity was reduced using dumbbells versus barbell (P = 0.007, ES = 0.73) and dumbbells versus Smith machine (P = 0.003, ES = 0.62). In conclusion, high stability requirements in the chest press (dumbbells) result in similar (pectoralis major and anterior deltoid), lower (triceps brachii) or higher (biceps brachii) muscle activity. These findings have implications for athletic training and rehabilitation.
The aim of this study was to examine the effects of a stable surface (bench) vs. an unstable surface (Swiss ball) on muscle activation when performing the dumbbell chest press and shoulder press. Sixteen healthy men (24.19 +/- 2.17 years) performed 1 repetition maximum (1RM) tests for the chest press and shoulder press on a stable surface. A minimum of 48 hours post 1RM, subjects returned to perform 3 consecutive repetitions each of the chest press and shoulder press at 80% 1RM under 4 different randomized conditions (chest press on bench, chest press on Swiss ball, shoulder press on bench, shoulder press on Swiss ball). Electromyography was used to assess muscle activation of the anterior deltoid, pectoralis major, and rectus abdominus. The results revealed no significant difference in muscle activation between surface types for either exercise. This suggests that using an unstable surface neither improves nor impairs muscle activation under the current conditions. Coaches and other practitioners can expect similar muscle activation when using a Swiss ball vs. a bench.
The bench press exercise exists in multiple forms including the machine and free weight bench press. It is not clear though how each mode differs in its effect on muscle activation. The purpose of this study was to compare muscle activation of the anterior deltoid, medial deltoid, and pectoralis major during a Smith machine and free weight bench press at lower (70% 1 repetition maximum [1RM]) and higher (90% 1RM) intensities. Normalized electromyography amplitude values were used during the concentric phase of the bench press to compare muscle activity between a free weight and Smith machine bench press. Participants were classified as either experienced or inexperienced bench pressers. Two testing sessions were used, each of which entailed either all free weight or all Smith machine testing. In each testing session, each participant's 1RM was established followed by 2 repetitions at 70% of 1RM and 2 repetitions at 90% of 1RM. Results indicated greater activation of the medial deltoid on the free weight bench press than on the Smith machine bench press. Also, there was greater muscle activation at the 90% 1RM load than at the 70% 1RM load. The results of this study suggest that strength coaches should consider choosing the free weight bench press over the Smith machine bench press because of its potential for greater upper-body muscular development.
There is considerable demand for information on the effectiveness of various resistance exercises for improving physical performance, and on how exercise programs must match functional activities to produce the greatest performance gains (training specificity). Evidence supports exercise-type specificity; the greatest training effects occur when the same exercise type is used for both testing and training. Range-of-motion (ROM) specificity is supported; strength improvements are greatest at the exercised joint angles, with enough carryover to strengthen ROMs precluded from direct training due to injury. Velocity specificity is supported; strength gains are consistently greatest at the training velocity, with some carryover. Some studies have produced a training effect only for velocities at and below the training velocity while others have produced effects around the training velocity. The little, mainly isokinetic, evidence comparing different exercise velocities for improving functional performance suggests that faster exercise best improves fast athletic movements. Yet isometric exercise can improve actions like the vertical jump, which begin slowly. The rate of force application may be more important in training than actual movement speed. More research is needed into the specificity and efficacy of resistance exercise. Test populations should include both males and females of various ages and rehabilitation patients.
The objective of this study was to determine differences in isometric force output, muscle activation (interpolated twitch technique), and electromyographic activity of the quadriceps, plantar flexors (PF), and their antagonists under stable and unstable conditions. Instability in subjects was introduced by making them perform contractions while seated on a "Swiss ball." Eight male subjects performed unilateral leg extensor (LE) and PF contractions while seated on a bench (LE), chair (PF), or a ball. Unstable LE and PF forces were 70.5 and 20.2% less than their stable counterparts, respectively. Unstable quadriceps and PF activation averaged 44.3 and 2.9% less than activation under stable conditions. Unstable antagonist/agonist ratios were 40.2 and 30.7% greater than stable ratios in the LE and PF protocols, respectively. The greater decrements with LE can be attributed to the instability of only 2 points of floor contact, rather than 3 points of floor contact as with the PF. Swiss balls may permit a strength training adaptation of the limbs, if instability is moderate, allowing the production of overload forces.
Swiss Balls used as a platform for training provide an unstable environment for force production. The objective of this study was to measure differences in force output and electromyographic (EMG) activity of the pectoralis major, anterior deltoid, triceps, latissimus dorsi, and rectus abdominus for isometric and dynamic contractions under stable and unstable conditions. Ten healthy male subjects performed a chest press while supported on a bench or a ball. Unstable isometric maximum force output was 59.6% less than under stable conditions. However, there were no significant differences in overall EMG activity between the stable and unstable protocols. Greater EMG activity was detected with concentric vs. eccentric or isometric contractions. The decreased balance associated with resistance training on an unstable surface may force limb musculature to play a greater role in joint stability. The diminished force output suggests that the overload stresses required for strength training necessitate the inclusion of resistance training on stable surfaces.
The purpose of this cross-sectional study was to evaluate the effect of unstable and unilateral resistance exercises on trunk muscle activation. Eleven subjects (6 men and 5 women) between 20 and 45 years of age participated. Six trunk exercises, as well as unilateral and bilateral shoulder and chest presses against resistance, were performed on stable (bench) and unstable (Swiss ball) bases. Electromyographic activity of the upper lumbar, lumbosacral erector spinae, and lower-abdominal muscles were monitored. Instability generated greater activation of the lower-abdominal stabilizer musculature (27.9%) with the trunk exercises and all trunk stabilizers (37.7-54.3%) with the chest press. There was no effect of instability on the shoulder press. Unilateral shoulder press produced greater activation of the back stabilizers, and unilateral chest press resulted in higher activation of all trunk stabilizers, when compared with bilateral presses. Regardless of stability, the superman exercise was the most effective trunk-stabilizer exercise for back-stabilizer activation, whereas the side bridge was the optimal exercise for lower-abdominal muscle activation. Thus, the most effective means for trunk strengthening should involve back or abdominal exercises with unstable bases. Furthermore, trunk strengthening can also occur when performing resistance exercises for the limbs, if the exercises are performed unilaterally.
The objective of this study was to determine differences in electromyographic (EMG) activity of the soleus (SOL), vastus lateralis (VL), biceps femoris (BF), abdominal stabilizers (AS), upper lumbar erector spinae (ULES), and lumbo-sacral erector spinae (LSES) muscles while performing squats of varied stability and resistance. Stability was altered by doing the squat movement on a Smith machine, a free squat, and while standing on two balance discs. Fourteen male subjects performed the movements. Activities of the SOL, AS, ULES, and LSES were highest during the unstable squat and lowest with the Smith machine protocol (p < 0.05). Increased EMG activity of these muscles may be attributed to their postural and stabilization role. Furthermore, EMG activity was higher during concentric contractions compared to eccentric contractions. Performing squats on unstable surfaces may permit a training adaptation of the trunk muscles responsible for supporting the spinal column (i.e., erector spinae) as well as the muscles most responsible for maintaining posture (i.e., SOL).
Surface instability is a common addition to traditional rehabilitation and strength exercises with the aim of increasing muscle activity, increasing exercise difficulty and improving joint proprioception. The aim of the current study was to determine if performing upper body closed kinetic chain exercises on a labile surface (Swiss ball) influences myoelectric amplitude when compared with a stable surface.
Thirteen males were recruited from a convenience sample of college students. Surface electromyograms were recorded from the triceps, pectoralis major, latissimus dorsi, rectus abdominis and external oblique while performing push up exercises with the feet or hands placed on a bench and separately on a Swiss ball. A push up plus exercise was also evaluated with hands on the support surface.
Not all muscles responded with an increase in muscle activity. The pectoralis major muscle was not influenced by surface stability. The triceps and rectus abdominis muscles showed increases in muscle activity only when the hands were on the unstable surface. The external oblique muscle was only influenced by surface stability during the performance of the push up plus exercise. No muscle showed a change in activation level when the legs were supported by the Swiss ball instead of the bench.
Muscle activity can be influenced by the addition of surface instability however an increase in muscle activity does not influence all muscles in all conditions. The relationship between the participant's center of mass, the location of the unstable surface and the body part contacting the Swiss ball may be important factors in determining the muscle activation changes following changes in surface stability.
There are many instances in daily life and sport in which force must be exerted when an individual performing the task is in an unstable condition. Instability can decrease the externally-measured force output of a muscle while maintaining high muscle activation. The high muscle activation of limbs and trunk when unstable can be attributed to the increased stabilization functions. The increased stress associated with instability has been postulated to promote greater neuromuscular adaptations, such as decreased co-contractions, improved coordination, and confidence in performing a skill. In addition, high muscle activation with less stress on joints and muscles could also be beneficial for general musculoskeletal health and rehabilitation. However, the lower force output may be detrimental to absolute strength gains when resistance training. Furthermore, other studies have reported increased co-contractions with unstable training. The positive effects of instability resistance training on sports performance have yet to be quantified. The examination of the literature suggests that when implementing a resistance training program for musculoskeletal health or rehabilitation, both stable and unstable exercises should be included to ensure an emphasis on both higher force (stable) and balance (unstable) stressors to the neuromuscular system.
The swiss is widely used in the recreational training environment as a supplement to conventional resistance training. One such application is to use the swiss ball as a bench support for bench press exercise. There is no evidence to indicate that the use of a swiss ball is beneficial for resistance training exercise. This study investigated muscle activity using surface electromyography of upper-body and abdominal muscles during the concentric and eccentric phases of the bench press on and off a swiss ball. Volunteers for this study were 14 resistance-trained subjects who performed isolated concentric and eccentric bench press repetitions using the 2 test surfaces with a 2-second cadence at a load equivalent to 60% maximum force output. The average root mean square of the muscle activity was calculated for each movement, and perceived exertion during the tasks was collected using a Borg Scale. The results of the study showed that deltoid and abdominal muscle activity was increased for repetitions performed using the swiss ball. Increased deltoid muscle activity supports previous findings for increased activity when greater instability is introduced to the bench press movement. Abdominal muscle activity increases were not hypothesized, but this finding provides scientific evidence for anecdotal reasoning behind swiss ball use as a potential core stability training device.
The purpose of this study was to determine the impact of a very slow (VS) velocity and a self-selected volitional (VOL) velocity at varying intensities on repetition number, peak force, peak power, and total volume in the squat and shoulder press exercises. On separate testing days, 9 resistance trained men (age: 23.9 +/- 2.5 years; height: 174.8 +/- 6.5 cm; body mass: 80.1 +/- 12.4 kg) performed a squat (SQ) and shoulder press (SP) exercise at 60 or 80% of 1 repetition maximum (1RM) at either VOL or VS (10-second eccentric and 10-second concentric actions) velocity for as many repetitions as possible. Force, power, and volume (repetitions x kg) were also determined. Subjects performed significantly fewer repetitions (p < or = 0.05) in the VS exercises (60% VS SQ 5 +/- 1 vs. VOL SQ 24 +/- 2; 80% VS SQ 2 +/- 0 vs. VOL SQ 12 +/- 1; 60% VS SP 4 +/- 1 vs. VOL SP 14 +/- 2; 80% VS SP 1 +/- 0 vs. VOL SP 6 +/- 1). Peak force and power were significantly higher at the VOL speed (peak force [in newtons]: 60% VS SQ 564.4 +/- 77.3 vs. VOL SQ 1229.0 +/- 134.9 N; 80% VS SQ 457.3 +/- 27.9 vs. VOL SQ 1059.3 +/- 104.7 N; 60% VS SP 321.6 +/- 37.8 vs. VOL SP 940.7 +/- 144.8 N; 80% VS SP 296.5 +/- 24.7 vs. VOL SP 702.5 +/- 57.7 N; and peak power [in watts]: 60% VS SQ 271.2 +/- 40.1 vs. VOL SQ 783.2 +/- 129.1 W; 80% VS SQ 229.3 +/- 49.5 vs. VOL SQ 520.2 +/- 85.8 W; 60% VS SP 91.3 +/- 21.9 vs. VOL SP 706.6 +/- 151.4 W; 80% VS SP 78.1 +/- 19.8 vs. VOL SP 277.6 +/- 46.4 W). VOL speed elicited higher total volume than the VS velocity. The results of this study indicate that a VS velocity may not elicit appropriate levels of force, power, or volume to optimize strength and athletic performance.
The purpose of this study was to investigate the effectiveness of instability training in the recruitment of core stabilizing muscles during dynamic multijoint movement. Surface electromyography (EMG) was measured from 6 muscles (latissimus dorsi, rectus abdominus, internal obliques, erector spinae, and soleus) while subjects performed a 9.1-kg bench press on stable and unstable surfaces. There were 4 exercises in total: (a) stable surfaces for shoulders and feet, (b) upper-body instability, (c) lower-body instability, and (d) dual instability. Five seconds of EMG were recorded during each bench press and were subsequently smoothed with root mean squares calculated for the entire time-series. A repeated-measures analysis of variance (ANOVA) was used to test overall differences between exercise conditions for each muscle. Paired equal variance t-tests with a stepwise Bonferroni correction for multiple contrasts (alpha = 0.05/total number of contrasts) were performed for muscles with significant repeated-measures ANOVA results. The results show significant increases in EMG with increasing instability. Specifically, the dual instability bench press resulted in the greatest mean muscle activation of the 3 stability conditions, with single instability conditions being significantly greater than the stable condition. This pattern of results is consistent with the position that performing the bench press in a progressively unstable environment may be an effective method to increase activation of the core stabilizing musculature, while the upper- and lower-body stabilizers can be activated differentially depending on the mode of instability.
The purpose of this study was to examine the extent of activation in various trunk muscles during dynamic weight-training and isometric instability exercises. Sixteen subjects performed squats and deadlifts with 80% 1 repetition maximum (1RM), as well as with body weight as resistance and 2 unstable calisthenic-type exercises (superman and sidebridge). Electromyographic (EMG) activity was measured from the lower abdominals (LA), external obliques (EO), upper lumbar erector spinae (ULES), and lumbar-sacral erector spinae (LSES) muscle groups. Results indicated that the LSES EMG activity during the 80% 1RM squat significantly exceeded 80% 1RM deadlift LSES EMG activity by 34.5%. The LSES EMG activity of the 80% 1RM squat also exceeded the body weight squat, deadlift, superman, and sidebridge by 56, 56.6, 65.5, and 53.1%, respectively. The 80% 1RM deadlift ULES EMG activity significantly exceeded the 80% 1RM squat exercise by 12.9%. In addition, the 80% 1RM deadlift ULES EMG activity also exceeded the body weight squat, deadlift, superman, and sidebridge exercises by 66.7, 65.5, 69.3, and 68.6%, respectively. There were no significant changes in EO or LA activity. Therefore, the augmented activity of the LSES and ULES during 80% 1RM squat and deadlift resistance exercises exceeded the activation levels achieved with the same exercises performed with body weight and selected instability exercises. Individuals performing upright, resisted, dynamic exercises can achieve high trunk muscle activation and thus may not need to add instability device exercises to augment core stability training.
This brief review examines some of the methods used to infer central control strategies from surface electromyogram (EMG) recordings. Among the many uses of the surface EMG in studying the neural control of movement, the review critically evaluates only some of the applications. The focus is on the relations between global features of the surface EMG and the underlying physiological processes. Because direct measurements of motor unit activation are not available and many factors can influence the signal, these relations are frequently misinterpreted. These errors are compounded by the counterintuitive effects that some system parameters can have on the EMG signal. The phenomenon of crosstalk is used as an example of these problems. The review describes the limitations of techniques used to infer the level of muscle activation, the type of motor unit recruited, the upper limit of motor unit recruitment, the average discharge rate, and the degree of synchronization between motor units. Although the global surface EMG is a useful measure of muscle activation and assessment, there are limits to the information that can be extracted from this signal.
The objective of this study was to measure the electromyographic (EMG) activity of the soleus, bicep femoris, rectus femoris, lower abdominal, and lumbosacral erector spinae (LSES) muscles with a variety of (a) instability devices, (b) stable and unstable (Dyna Disc) exercises, and (c) a fatiguing exercise in 16 highly conditioned individuals. The device protocol had participants assume standing and squatting postures while balancing on a variety of unstable platforms (Dyna Disc, BOSU ball, wobble board, and a Swiss ball) and a stable floor. The exercise protocol had subjects performing, static front lunges, static side lunges, 1-leg hip extensions, 1-leg reaches, and calf raises on a floor or an unstable Dyna Disc. For the fatigue experiment, a wall sit position was undertaken under stable and unstable (BOSU ball) conditions. Results for the device experiment demonstrated increased activity for all muscles when standing on a Swiss ball and all muscles other than the rectus femoris when standing on a wobble board. Only lower abdominals and soleus EMG activity increased while squatting on a Swiss ball and wobble board. Devices such as the Dyna Disc and BOSU ball did not exhibit significant differences in muscle activation under any conditions, except the LSES in the standing Dyna Disc conditions. During the exercise protocol, there were no significant changes in muscle activity between stable and unstable (Dyna Disc) conditions. With the fatigue protocol, soleus EMG activity was 51% greater with a stable base. These results indicate that the use of moderately unstable training devices (i.e., Dyna Disc, BOSU ball) did not provide sufficient challenges to the neuromuscular system in highly resistance-trained individuals. Since highly trained individuals may already possess enhanced stability from the use of dynamic free weights, a greater degree of instability may be necessary.
The exercise technique of the dumbbell seated shoulder press is described and demonstrated in this column.
The purpose of the study was to compare six-repetition maximum (6-RM) loads and muscle activity in bench press on three surfaces, namely stable bench, balance cushion and Swiss ball. 16 healthy, resistance-trained males (age 22.5±2.0 years, stature 1.82±6.6 m, and body mass 82.0±7.8 kg) volunteered for three habituation/strength testing sessions, and one experimental session. In randomized order on the three surfaces, 6-RM strength and electromyographic activity of pectoralis major, deltoid anterior, biceps brachii, triceps brachii, rectus abdominis, oblique external and erector spinae were assed. Relative to stable bench, the 6-RM strength was ∼93% for balance cushion (P≤0.001) and ∼92% for Swiss ball (P=0.008); the pectoralis major EMG activity was ∼90% using the balance cushion (P=0.080) and ∼81% using Swiss ball (P=0.006); the triceps EMG was ∼79% using the balance cushion (P=0.028) and ∼69% using the Swiss ball (P=0.002). Relative to balance cushion, the EMG activity in pectoralis, triceps and erector spinae using Swiss ball was ∼89% (P=0.016), ∼88% (P=0.014) and ∼80% (P=0.020), respectively. In rectus abdominis, the EMG activity relative to Swiss ball was ∼69% using stable bench (P=0.042) and ∼65% using the balance cushion (P=0.046). Similar EMG activities between stable and unstable surfaces were observed for deltoid anterior, biceps brachii and oblique external. In conclusion, stable bench press had greater 6-RM strength and triceps and pectoralis EMG activity compared to the unstable surfaces. These findings have implications for athletic training and rehabilitation, as they demonstrate an inferior effect of unstable surfaces on muscle activation of prime movers and strength in bench press. If an unstable surface in bench press is desirable, a balance cushion should be chosen instead of a Swiss ball.
The purpose of the study was to compare force output and muscle activity of leg and trunk muscles in isometric squats executed on stable surface (i.e. floor), power board, BOSU ball and balance cone. Fifteen healthy males (23.3 ± 2.7 years, mass: 80.5 ± 8.5 kg, height: 1.81 ± 0.09 m) volunteered. The force output and electromyographic (EMG) activities of the rectus femoris, vastus medialis, vastus lateralis, biceps femoris, soleus, rectus abdominis, oblique external and erector spinae were assessed. The order of the surfaces was randomized. One familiarization session was executed prior to the experimental test. Compared to stable surface (749 ± 222 N), the force output using power board was similar (-7%, P = 0.320), but lower for BOSU ball (-19%, P = 0.003) and balance cone (-24%, P ≤ 0.001). The force output using BOSU ball and balance cone was ∼13% (P = 0.037) and ∼18% (P = 0.001) less than the power board. There were similar EMG activities between the surfaces in all muscles except for rectus femoris, in which stable squat provided greater EMG activity than the other exercises (P = 0.004 - 0.030). Lower EMG activity was observed in rectus femoris using balance cone compared to BOSU ball (P = 0.030). In conclusion, increasing the instability of the surface during maximum effort isometric squats usually maintains the muscle activity of lower limb and superficial trunk muscles although the force output is reduced. This suggests that unstable surfaces in the squat may be beneficial in rehabilitation and as a part of periodized training programs, as similar muscle activity can be achieved with reduced loads.
Van den Tillaar, R, and Sæterbakken, A. The sticking region in three chest-press exercises with increasing degrees of freedom. J Strength Cond Res 26(11): 2962-2969, 2012-The purpose was to investigate the effect of 3 chest-press exercises with different degrees of freedom upon the sticking region and muscle activity in maximal attempts. It was hypothesized that, with increasing degrees of freedom, the sticking region (the weakest region during the lift) would be longer because the muscles need to use a part of their ability to control these increasing degrees of freedom during the exercise. Furthermore, the prime movers would have the same muscle activity, but the biceps muscle activity would increase when the degrees of freedom increases because of the enhanced control of the upward movement. Eleven male subjects (age 22.6 ± 1.7 years, body mass 78.6 ± 8.0 kg, stature 1.80 ± 0.07 m) with at least 1 year of bench press training experience participated in this study. Every subject was tested in 1 repetition maximum (1RM) in the 3 chest-press exercises. During the attempts, kinematics and muscle activity were recorded and analyzed in 4 different regions (downward, presticking, sticking, and poststicking). The participants achieved the highest 1RM strength using the free barbell (106.4 ± 15.5 kg), followed by the Smith machine (103.6 ± 14.8 kg) and dumbbells (89.5 ± 13.7 kg). Furthermore, muscle activity differences (electromyographic) between the 3 different exercises and the muscle activation between the 4 different regions were found. The length of the different lifting regions together with muscle activity was different between the exercises. However, the differences found did not follow the line of increasing degrees of freedom that would result in a longer sticking region. Therefore, it is possible to choose to train a particular chest press exercise with the purpose of training a particular muscle more than the others.
The purpose of this investigation was to determine the effect of stable and unstable conditions on one repetition maximum strength and muscle activity during dynamic squatting using absolute and relative loading.
Ten recreationally weight-trained males participated in this study (age = 24.1 +/- 2.0 y, height = 178.0 +/- 5.6 cm, body mass = 83.7 +/- 13.4 kg, 1RM/body mass = 1.53 +/- 0.31), which involved two laboratory sessions separated by 1 wk. Linear position transducers were used to track bar displacement while subjects stood on a force plate for all trials. Vastus lateralis (VL), biceps femoris (BF) and erector spinae (L1) muscle activity (average integrated EMG [IEMG]) was also recorded during all trials. During the first session subjects complete a one repetition maximum test in a stable dynamic squat (S1RM = 128.0 +/- 31.4 kg) and an unstable dynamic squat (U1RM = 83.8 +/- 17.3 kg) in a randomized order with a 30-min rest period between conditions. The second session consisted of the performance of three trials each for 12 different conditions (unstable and stable squats using three different absolute loads [six conditions] and unstable and stable squats using three different relative loads [six conditions]).
Results revealed a statistically significant difference between S1RM and U1RM values (P < or = .05). The stable trials resulted in the same or a significantly higher value for VL, BF and L1 muscle activity in comparison with the unstable trials for all twelve conditions.
Unstable squatting is of equal or less (depending on the loading condition) benefit to improving or maximizing muscle activity during resistance exercise.
In an attempt to mimic everyday activities that are performed in 3-dimensional environments, exercise programs have been designed to integrate training of the trunk muscles with training of the extremities. Many believe that the most effective way to recruit the core stabilizing muscles is to execute traditional exercise movements on unstable surfaces. However, physical activity is rarely performed with a stable load on an unstable surface; usually, the surface is stable, and the external resistance is not. The purpose of this study was to evaluate muscle activity of the prime movers and core stabilizers while lifting stable and unstable loads on stable and unstable surfaces during the seated overhead shoulder press exercise. Thirty resistance-trained subjects performed the shoulder press exercise for 3 sets of 3 repetitions under 2 load (barbell and dumbbell) and 2 surface (exercise bench and Swiss ball) conditions at a 10 repetition maximum relative intensity. Surface electromyography (EMG) measured muscle activity for 8 muscles (anterior deltoid, middle deltoid, trapezius, triceps brachii, rectus abdominis, external obliques, and upper and lower erector spinae). The average root mean square of the EMG signal was calculated for each condition. The results showed that as the instability of the exercise condition increased, the external load decreased. Triceps activation increased with external resistance, where the barbell/bench condition had the greatest EMG activation and the dumbbell/Swiss ball condition had the least. The upper erector spinae had greater muscle activation when performing the barbell presses on the Swiss ball vs. the bench. The findings provide little support for training with a lighter load using unstable loads or unstable surfaces.
This study evaluated the effect of remote voluntary contractions(RVC) on concentric isokinetic knee extensor and flexor peak torque, rate of torque development, power, and work, the activation of the affected muscles, and gender differences therein.
Eleven men and 12 women were evaluated with EMG and isokinetic dynamometry during knee extension and flexion tests in RVC and baseline (NO-RVC) test conditions. The RVC condition included jaw clenching, hand gripping, and the Valsalva maneuver. A two-way mixed ANOVA with repeated measures for test condition was used to evaluate the main effects for each isokinetic measure, as well as the EMG of the prime movers, their antagonist,and the muscles involved in the RVC, and the interaction between test condition and gender.
Significant interactions between test condition and gender indicate differences in response to RVC during knee extension tests for power and work (P < or = 0.05) and for knee flexion tests for peak torque and power (P < or = 0.05). All subjects produced higher peak torque and power during knee extension in the RVC condition (P < or = 0.05). Men produced a higher rate of torque development and work during knee extension (P < or = 0.05) and a higher peak torque and power during knee flexion in the RVC condition (P < or = 0.05). Prime mover activation was greater in the RVC condition for most tests (P < or = 0.05). Women demonstrated lower bilateral flexor digitorum superficialis activation than men during all tests in the RVC condition (P < or = 0.05).
RVC increased the performance of several outcome variables assessed, which coincides with the concomitant increase in EMG of the prime movers.
The purpose of this experiment was to determine whether free weight or Smith machine squats were optimal for activating the prime movers of the legs and the stabilizers of the legs and the trunk. Six healthy participants performed 1 set of 8 repetitions (using a weight they could lift 8 times, i.e., 8RM, or 8 repetition maximum) for each of the free weight squat and Smith machine squat in a randomized order with a minimum of 3 days between sessions, while electromyographic (EMG) activity of the tibialis anterior, gastrocnemius, vastus medialis, vastus lateralis, biceps femoris, lumbar erector spinae, and rectus abdominus were simultaneously measured. Electromyographic activity was significantly higher by 34, 26, and 49 in the gastrocnemius, biceps femoris, and vastus medialis, respectively, during the free weight squat compared to the Smith machine squat (p < 0.05). There were no significant differences between free weight and Smith machine squat for any of the other muscles; however, the EMG averaged over all muscles during the free weight squat was 43% higher when compared to the Smith machine squat (p < 0.05). The free weight squat may be more beneficial than the Smith machine squat for individuals who are looking to strengthen plantar flexors, knee flexors, and knee extensors.
This study calculated IEMG values during the ascent and descent phases of the bench press and compared the values between lifts performed with free weights versus a guided weight machine. In Phase 1 of the study the 1-RM on each mode was determined for each subject. In Phase 2, EMG data were collected from five muscles of the upper extremity while each subject completed five trials at 80% of 1-RM and five trials at 60% of 1-RM for each mode. Linear envelopes were created from the EMG data of each trial, and IEMG values were calculated during the descent and ascent phases of each trial. Planned comparisons were used to compare mean IEMG values between the two loads within the same mode, and between the two modes at both the 60% and 80% loads. Results suggested greater muscle activity during the free-weight bench press, especially at the 60% 1-RM load, although there were notable differences among the patterns of individual subjects.
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.
The aim of this study was to assess the effects of variations in the volume and intensity of resistance training in highly skilled athletes on neural adaptive mechanisms: the maximality and pattern of neural drive. The maximality of muscle activation was measured using a high-resolution sample and hold amplifier to record interpolated twitches. The pattern of neural drive was measured by analysing isometric torque-time curves and electromyographic (EMG) characteristics during the performance of rapid isometric contractions at maximal effort. The volume and intensity of training were varied at 4-weekly intervals to systematically emphasize the development of strength, power and motor performance in 14 highly skilled track and field athletes (e.g. discus, hammer, javelin, shot put and weight). Knee extension strength increased significantly by 15% during steady maximal isometric contractions and by 24% during rapid isometric contractions at maximal effort after the 16-week training programme (P < 0.05). Increases in EMG amplitude and rate of EMG activation indicated that improvements to the pattern of neural drive occurred with sport-specific resistance training (P < 0.05). The maximality and pattern of neural drive did not change in the control group.
The purpose of this study was to examine the differences in activation levels and times of activation for the pectoralis major and anterior deltoid when performing the concentric phase of 3 upper-body lifts. Twelve college-age men and women with various degrees of lifting experience performed 3 repetitions using the 6 repetition maximum in a barbell bench press, dumbbell bench press, and dumbbell fly while being monitored for electromyographic activity in both muscles. Motor unit activation of both muscles was not significantly different during all 3 lifts. However, dumbbell flys had significantly less relative time of activation than did barbell or dumbbell bench presses. Therefore, dumbbell flys may be better suited as an auxiliary lift, whereas barbell and dumbbell bench presses may be used interchangeably in training programs. The compatibility of the barbell and dumbbell bench presses may aid lifters in overcoming training plateaus by alternating exercises for the same muscle groups.
The purpose of this study was to assess the effect of stable vs. unstable conditions on force output and muscle activity during an isometric squat. Nine men involved in recreational resistance training participated in the investigation by completing a single testing session. Within this session subjects performed isometric squats either while standing directly on the force plate (stable condition, S) or while standing on inflatable balls placed on top of the force plate (unstable condition, U). Electromyography (EMG) was recorded during both conditions from the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and medial gastrocnemius (G) muscles. Results indicated peak force (PF) and rate of force development (RFD) were significantly lower, 45.6% and 40.5% respectively, in the U vs. S condition (p < or = 0.05). Average integrated EMG values for the VL and VM were significantly higher in the S vs. U condition. VL and VM muscle activity was 37.3% and 34.4% less in U in comparison to S. No significant differences were observed in muscle activity of the BF or G between U and S. The primary finding in this investigation is that isometric squatting in an unstable condition significantly reduces peak force, rate of force development, and agonist muscle activity with no change in antagonist or synergist muscle activity. In terms of providing a stimulus for strength gain no discernable benefit of performing a resistance exercise in an unstable condition was observed in the current study.
This study compared the standing cable press (SCP) and the traditional bench press (BP) to better understand the biomechanical limitations of pushing from a standing position together with the activation amplitudes of trunk and shoulder muscles. A static biomechanical model (4D Watbak) was used to assess the forces that can be pushed with 2 arms in a standing position. Then, 14 recreationally trained men performed 1 repetition maximum (1RM) BP and 1RM single-arm SP exercises while superficial electromyography (EMG) of various shoulder and torso muscles was measured. The 1RM BP performance resulted in an average load (74.2 +/- 17.6 kg) significantly higher than 1RM single-arm SP (26.0 +/- 4.4 kg). In addition, the model predicted that pushing forces from a standing position under ideal mechanical conditions are limited to 40.8% of the subject's body weight. For the 1RM BP, anterior deltoid and pectoralis major were more activated than most of the trunk muscles. In contrast, for the 1RM single-arm SP, the left internal oblique and left latissimus dorsi activities were similar to those of the anterior deltoid and pectoralis major. The EMG amplitudes of pectoralis major and the erector muscles were larger for 1RM BP. Conversely, the activation levels of left abdominal muscles and left latissimus dorsi were higher for 1RM right-arm SP. The BP emphasizes the activation of the shoulder and chest muscles and challenges the capability to develop great shoulder torques. The SCP performance also relies on the strength of shoulder and chest musculature; however, it is whole-body stability and equilibrium together with joint stability that present the major limitation in force generation. Our EMG findings show that SCP performance is limited by the activation and neuromuscular coordination of torso muscles, not maximal muscle activation of the chest and shoulder muscles. This has implications for the utility of these exercise approaches to achieve different training goals.
Exercise or Swiss balls are increasingly being used with conventional resistance exercises. There is little evidence supporting the efficacy of this approach compared to traditional resistance training on a stable surface. Previous studies have shown that force output may be reduced with no change in muscle electromyography (EMG) activity while others have shown increased muscle EMG activity when performing resistance exercises on an unstable surface. This study compared 1RM strength, and upper body and trunk muscle EMG activity during the barbell chest press exercise on a stable (flat bench) and unstable surface (exercise ball). After familiarization, 13 subjects underwent testing for 1RM strength for the barbell chest press on both a stable bench and an exercise ball, each separated by at least 7 days. Surface EMG was recorded for 5 upper body muscles and one trunk muscle from which average root mean square of the muscle activity was calculated for the whole 1RM lift and the concentric and eccentric phases. Elbow angle during each lift was recorded to examine any range-of-motion differences between the two surfaces. The results show that there was no difference in 1RM strength or muscle EMG activity for the stable and unstable surfaces. In addition, there was no difference in elbow range-of-motion between the two surfaces. Taken together, these results indicate that there is no reduction in 1RM strength or any differences in muscle EMG activity for the barbell chest press exercise on an unstable exercise ball when compared to a stable flat surface. Moreover, these results do not support the notion that resistance exercises performed on an exercise ball are more efficacious than traditional stable exercises.