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Comparative Impacts of Plate-Loaded and Cable Resistance Machines on Muscle Activity and Joint Kinematics: 1690 Board #343
Abstract
Cable machines (CABLE) have become increasingly popular tools for resistance training; however, the relative impacts of plate-loaded machines (PLATE) versus CABLE on muscle utilization patterns and related kinematics is unclear.
PURPOSE: To examine differences in muscle activity and kinematics between CABLE and PLATE.
METHODS: Healthy participants (9M, 6F, height = 1.75 ± .07 m, mass = 75.70 ± 11.79 kg, age = 24.33 ± 4.88 yrs) completed 5 repetitions of overhead press, bicep curl, and chest press exercises with 8-RM loads on PLATE and CABLE in a randomized order. Muscular activities (rmsEMG, μV) of the pectoralis major (PM), anterior deltoid (AD), biceps brachii long head (BB), rectus abdominus (RA), external oblique (EO), and triceps brachii lateral head (TB) were measured using surface electromyography. Joint range of motion (ROM, rad) of the shoulder, elbow, hip, and knee was recorded using a high speed camera and assessed using Kinovea biomechanical analysis software. Independent-samples t-tests were conducted to examine the differences in rmsEMG and ROM between the CABLE and PLATE for each exercise.
RESULTS: Significantly higher rmsEMG values were observed during the biceps curl on CABLE in the PM (Mdiff ± SE = 68.99 ± 25.55, p = .017) and AD (Mdiff ± SE = 77.31 ± 24.10, p = .06), along with greater shoulder ROM (Mdiff ± SE = 7.51 ± 3.44, p = .036). The chest press produced significantly higher rmsEMG on CABLE in the BB (Mdiff ± SE = 120.24 ± 26.59, p < .001), RA (Mdiff ±SE = 39.78 ± 17.47, p = .039), and EO (Mdiff ± SE = 16.05 ± 5.93, p = .017), and significantly higher rmsEMG on PLATE in the TB (Mdiff ± SE = 157.35 ± 31.33, p < .001). CABLE also displayed significantly greater hip ROM (Mdiff ± SE = .037 ± .011, p < .001), knee ROM (Mdiff ± SE = .107, p < .001), and shoulder ROM (Mdiff ± SE = 1.277 ± .080, p < .001) for this exercise. The overhead press produced higher rmsEMG on the CABLE in the BB (Mdiff ± SE= 117.32 ± 25.82, p < .001) and EO (Mdiff ± SE = 11.60 ±3.82, p = .009) and significantly greater hip ROM (Mdiff ± SE = .037 ± .011, p < .001), knee ROM (Mdiff ± SE = .107, p < .001), and shoulder ROM (Mdiff ± SE = 1.277 ± .080, p < .001) than PLATE.
CONCLUSION: Our results argue for the use of CABLE over PLATE for increased muscle activation and ROM; however, their relative impacts on power, strength and functionality remain undetermined.
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The main objective of this study was to compare electromyography (EMG), heart rate (HR), and perceived exertion (PE) during different elbow flexion exercises in standing position (biceps curl [BC] and adapted BC [ABC]) and seated position (preacher BC [PBC]). Twenty healthy subjects performed the dynamic 1-repetition maximum (1RM) test. The following week (1 exercise per day), these exercises were performed at 25, 30, 35, and 40% 1RM at 1 minute for each one (20 repetitions). Biceps brachii and brachioradialis root mean square (RMS), HR, and PE were recorded in the 5th (R5), 10th (R10), 15th (R15), and 20th (R20) repetitions. Effects of exercise type (BC x ABC x PBC), load level (25% 1RM x 30% 1RM x 35% 1RM x 40% 1RM), and exercise duration (R5 x R10 x R15 x R20) were analyzed. The RMS of the elbow flexors in the PBC R20 was significantly lower than BC and ABC at 40% 1RM, and, in the same way, for all load levels, HR and PE were significantly lower in PBC R20 at 40% 1RM compared with BC and ABC. For all exercises, RMS, HR, and PE at 25% 1RM were significantly lower than at 40% 1RM. The execution of the exercises caused significant increases in the RMS, HR, and PE mainly between R5 compared with R15 and R20. In conclusion, different positions demand different neuromuscular (EMG), cardiovascular (HR), and sensorial (PE) responses. A decreased effort sensation in PBC at the same relative load level can contribute to better execution when standing and seated exercises are compared.
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 aim of the study was to compare the theoretical indicator of upper limb load with the physiological indicator of musculoskeletal load, which is present while performing a repetitive task (a normalized electromyography [EMG] amplitude recorded from the muscles of the upper limb involved in the performed task). In an experimental study of a repetitive task, the EMG signal from 5 main muscles of the shoulder girdle, arm and forearm was registered: extensor carpi radialis longus, flexor carpi ulnaris, deltoideus anterior, biceps brachii caput breve and trapezius descendent. The results of the study showed a strong correlation between the theoretical indicator (Integrated Cycle Load) and the physiological indicator (root mean square of a normalized EMG amplitude from the 5 muscles). This proves that the developed theoretical indicator can be accepted as an indicator of upper limb musculoskeletal load during a work task.
The role of intra-abdominal pressure (IAP) in unloading the spine has remained controversial. In the current study, a novel kinematics-based approach along with a nonlinear finite-element model were iteratively used to calculate muscle forces, spinal loads, and stability margin under prescribed postures and loads measured in in vivo studies. Four coactivity levels (none, low, moderate, and high) of abdominal muscles (rectus abdominis, external oblique, and internal oblique) were considered concurrently with a raise in IAP from 0 to 4 kPa when lifting a load of 180 N in upright standing posture and to 9 kPa when lifting the same load in forward trunk flexions of 40 degrees and 65 degrees. For comparison, reference cases with neither abdominal coactivity nor IAP were investigated as well. A raise in IAP unloaded and stabilized the spine when no coactivity was considered in the foregoing abdominal muscles for all lifting tasks regardless of the posture considered. In the upright standing posture, the unloading action of IAP faded away even in the presence of low level of abdominal coactivity while its stabilizing action continued to improve as abdominal coactivity increased to moderate and high levels. For lifting in forward-flexed postures, the unloading action of IAP disappeared only with high level of abdominal coactivities while its stabilizing action deteriorated as abdominal coactivities increased. The unloading and stabilizing actions of IAP, hence, appear to be posture and task specific.
The goal was to identify the anthropometric, jumping ability, and muscular strength measures which contributed most to discrimination among young women in track-and-field jumping (n = 20, Jumping group), volleyball (n = 20, Volleyball group), and girls in no activity (n = 20, Control group). Using analysis of covariance and discriminant analysis the Jumping group, as compared to the Volleyball group, had smaller elbow breadth, knee breadth, upper arm circumference, proximal-, mid-, and distal-thigh circumferences, sum of skinfolds, and mesomorphy rating, and Jumping athletes showed larger jump height and muscular strength than the Volleyball group. Measures which contributed most to the discrimination between these groups were the distal-thigh circumference and jump height. Results could, to some extent, help training orientation of young women athletes by identifying whatever factors affect the measures indicated here as the most sensitive discriminators.
Background:
Exercises that aim to stimulate muscular hypertrophy and increase neural drive to the muscle fibers should be used during rehabilitation. Thus, it is of interest to identify optimal exercises that efficiently achieve high muscle activation levels.
Objective:
The purpose of this study was to compare the muscle activation levels during push-up variations (ie, suspended push-ups with/without visual input on different suspension systems, and push-ups on the floor with/without additional elastic resistance) with the bench press exercise and the standing cable press exercise both performed at 50%, 70%, and 85% of the 1-repetition maximum.
Methods:
Young fit male university students (N = 29) performed 3 repetitions in all conditions under the same standardized procedures. Average amplitude of the electromyogram (EMG) root mean square for the rectus abdominis, external oblique, sternocostal head of the pectoralis major, anterior deltoid, long head of the triceps brachii, upper trapezius, anterior serratus, and posterior deltoid was recorded. The EMG signals were normalized to the maximum voluntary isometric contraction. The EMG data were analyzed with repeated-measures analysis of variance with a Bonferroni post hoc.
Results and conclusions:
Elastic-resisted push-ups induce similar EMG stimulus in the prime movers as the bench press at high loads while also providing a greater core challenge. Suspended push-ups are a highly effective way to stimulate abdominal muscles. Pectoralis major, anterior deltoid, and anterior serratus are highly elicited during more stable pushing conditions, whereas abdominal muscles, triceps brachii, posterior deltoid, and upper trapezius are affected in the opposite manner.
Abstract This study examined anterior chain whole body linkage exercises, namely the body saw, hanging leg raise and walkout from a push-up. Investigation of these exercises focused on which particular muscles were challenged and the magnitude of the resulting spine load. Fourteen males performed the exercises while muscle activity, external force and 3D body segment motion were recorded. A sophisticated and anatomically detailed 3D model used muscle activity and body segment kinematics to estimate muscle force, and thus sensitivity to each individual's choice of motor control for each task. Gradations of muscle activity and spine load characteristics were observed across tasks. On average, the hanging straight leg raise created approximately 3000 N of spine compression while the body saw created less than 2500 N. The hanging straight leg raise created the highest challenge to the abdominal wall (>130% MVC in rectus abdominis, 88% MVC in external oblique). The body saw resulted in almost 140% MVC activation of the serratus anterior. All other exercises produced substantial abdominal challenge, although the body saw did so in the most spine conserving way. These findings, along with consideration of an individual's injury history, training goals and current fitness level, should assist in exercise choice and programme design.
Nonlinear analysis techniques are necessary to understand the complexity of the EMG. The purpose of the present study was to determine the fractal dimension of surface EMO obtained from the biceps brachii of normal subjects during isokinetic flexion-extension of the arm. The measurements were obtained with different loading conditions on the arm and for various rates of flexion-extension. Fractal dimensions of the surface EMG signals were calculated for each of these conditions. ANOVA results showed statistically significant differences between the fractal dimensions calculated for different loading conditions and rates of flexion-extension (P <- 0.005). Linear regression analysis showed a correlation coefficient of 0.99 between the fractal dimension and the load, and a correlation coefficient of 0.98 between the fractal dimension and the rate of flexion-extension. The results of the study show that the fractal dimension can be used along with other parameters to characterize the EMG signal.
The aim of the study was to evaluate differences in the loading of glenohumeral joint muscles between a cable pulley machine (CP) and variable resistance machine (VR) during axial humeral external rotation.
Eleven healthy male subjects took part in the study. Intramuscular electromyography from five muscles of the shoulder (medial deltoid, supraspinatus, infraspinatus and upper part of the trapezius), torque and power output was measured at different rotation angles and with different loads (10%, 50% and 100% of 1RM). Also the compressive and shear force in the glenohumeral joint was analyzed at the horizontal level at angles of rotation. External rotation was performed with a self-selected velocity on the scapular plane.
In the CP the range of movement became narrower than in the VR with increasing workload (P<0.05). The activity of the infraspinatus did not grow in the CP after 50% load, while it did in the VR (P<0.01). The upper part of the trapezius was activated less in the CP than in the VR (P<0.01) machine when using 50% and 100% loads. In comparison with the CP, the shear forces that pull the head of the humerus in a posterior direction were more evenly distributed in the VR than in the CP at different angles of rotation (P<0.001).
The VR seems to make a broader range of motion possible, lager activation the primary external rotators and evenly distributed shear forces than the CP. However, performing the exercise with VR and high load also activates the upper part of the trapezius.
These findings can be used in the development of exercise designs, methods and equipment for shoulder injury rehabilitation.
The purpose of this study was to investigate the possible existence of systematic differences between moment-length properties of the rectus femoris muscle of cyclists/speed skaters and runners. In cycling/speed skating the rectus femoris is used at a shorter length than in running because of the pronounced flexion at the hip joint. It was speculated that using the rectus femoris chronically at different lengths would result in different moment-length relations for the two groups of athletes. Moment-length relations of rectus femoris muscles were determined using an adaptation of procedures outlined in the literature. Four subjects in each group performed 13 isometric knee extensions on a Cybex II dynamometer in each of three testing sessions. Knee and hip angles were varied in a systematic way to allow the determination of moment-length relations over a wide range of normal rectus femoris lengths. It was found that cyclists tended to be stronger at short compared with long rectus femoris lengths, whereas the opposite was true for runners. This finding may be associated with an adaptation of the rectus femoris muscle to the requirements of cycling and running or may show an inherited difference in the muscles of the athletes that existed before they became involved in their respective sports. The data of this study do not allow us to distinguish between these two possible factors.
The present study evaluated the effect of limited range of motion (ROM) variable resistance training on full ROM strength development. Twenty-eight men and 31 women were randomly assigned to one of the three training groups (A, B, AB) or a control group (C). A, B, and AB performed variable resistance bilateral knee extension exercise 2 (N = 25) or 3 (N = 19) d.wk-1 for 10 wk with an amount of weight that allowed one set of 7-10 repetitions. Group A trained in a ROM limited to 120 degrees to 60 degrees of knee flexion. Group B trained in a ROM limited to 60 degrees to 0 degrees of knee flexion. Group AB trained full ROM. Prior to and immediately following training, isometric knee extension strength was evaluated at 9 degrees, 20 degrees, 35 degrees, 50 degrees, 65 degrees, 80 degrees, 95 degrees, and 110 degrees of knee flexion with a Nautilus knee extension tensiometer. Reliability coefficients for repeated measurements of isometric strength at multiple joint angles were high (r = 0.86-0.95, P less than 0.01; SEE = 23.1-37.2 N.m). Compared to the control group, all training groups improved in isometric strength (P less than 0.01 at each angle tested except for group A at 9 degrees and 20 degrees of knee flexion and group B at 95 degrees of flexion. Isometric strength gains for group AB were similar throughout the full ROM. Isometric strength gains for the limited ROM trained groups were greater in the trained ROM than in the untrained ROM (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Eccentric resistance training is an important component of many rehabilitation protocols. The adaptations following eccentric training are poorly understood in relation to concentric training. The purpose of this investigation was to examine the effects of unilateral eccentric leg extension weight training and detraining on joint angle specificity, cross-training, and the bilateral deficit. Seventeen males volunteered to be subjects for this investigation and were divided into an eccentric training group (N = 9) and a control group (N = 8). The eccentric group performed 8 weeks of unilateral eccentric weight training with the nondominant limb three times per week (3-5 sets of six repetitions) followed by 8 weeks of detraining. These subjects were tested pretraining, posttraining, and following detraining for maximal isometric strength at three joint angles (15, 45, and 75 degrees) in both limbs as well as for the one-repetition maximum (1-RM) eccentric strength of the trained limb, untrained limb, and bilaterally. The results of this investigation indicated that the effects of the eccentric weight training were joint angle specific [significant increases at 45 and 75 degrees (p < 0.05)]. This effect was found in both limbs, indicating a cross-training effect that was joint angle specific. The results from the 1-RM analyses indicated that the bilateral deficit exists for eccentric contractions (untrained limb > bilateral at pretraining) and that unilateral eccentric training increases this effect (trained and untrained limbs > bilateral posttraining); however, the unilateral training also resulted in increased bilateral strength. Both the 1-RM and isometric analyses showed that the training effects persisted over 8 weeks of detraining.
This study was conducted to quantify the normalized amplitudes of the abdominal wall and back extensor musculature during a variety of push-up styles. We also sought to quantify their impact on spinal loading by calculating spinal compression and torque generation in the L4-5 area.
Ten university-age participants, nine males and one female, in good to excellent condition, volunteered to participate in this study. All participants were requested to perform a maximum of 12 different push-up exercises, three trials per exercise. Surface electromyographic data (EMG) were collected bilaterally on rectus abdominis, external oblique, internal oblique, latissimus dorsi, and erector spinae muscles, and unilaterally (right side) on pectoralis major, triceps brachii, biceps brachii, and anterior deltoid muscles. Spine kinetics were obtained using an anatomically detailed model of the torso/spine.
This study revealed that more dynamic push-ups (i.e., ballistic, with hand movement) required more muscle activation and higher spine load, whereas placing labile balls under the hands only resulted in modest increases in spine load. Right rectus abdominis (RA) activation was significantly higher than left RA activation during the left hand forward push-up and vice versa for the right hand forward push-up (P < 0.001). External oblique (EO) demonstrated the same switch in dominance during staggered hand push-ups (P < 0.01). The one-arm push-up resulted in the highest spine compression. Skilled participants showed greater synchronicity with peak muscle activation (plyometric type of contractions) during ballistic push-ups.
These data will help guide exercise selection for individuals with differing training objectives and injury history.
The principle of specificity in muscle training requires the training mode to reflect the desired outcome. The observed similarity of lower limb movements during recumbent cycling to the functional movements sit-to-stand and step-up presents the possibility of using recumbent cycling in a rehabilitation context. This may reduce the need to practice the actual task which in some, less able, patients may be labour intensive and patient fatiguing. To date no studies have compared recumbent cycling to these functional movements. This study therefore aimed to compare the lower limb kinematics and muscle activity between recumbent cycling and both sit-to-stand and step-up movements.
Electromyographic and kinematic signals from 12 young (mean age 42.1 years) healthy participants were collected during the performance of three activities: (1) cycling at 60 rpm, (2) sit-to-stand and (3) a single step-up. Only the extension phase of each movement was compared.
Although the results demonstrated differences in joint movement and muscle activation, e.g., greater gastrocnemius activity during recumbent cycling (P<0.00), knee range of motion and average root mean square activity for rectus femoris, biceps femoris and the sum of the average activity for five muscles recorded showed no difference (P>0.05) suggesting that there was sufficient agreement to support the use of recumbent cycling as a specific training modality for the sit-to-stand and step-up movements. This finding may have positive implications for the rehabilitation of a wide range of patients in the early stages of rehabilitation.
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.
Cram's Introduction to Surface Electromyography
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