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Comparison of the Effects of Electrical Stimulation and Exercise on Abdominal Musculature

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The purpose of this study was to test the effect of electrical stimulation and volitional exercise on abdominal muscle strength and endurance. Changes of voltage, current, and tissue resistance were analyzed to determine tissue conditioning to stimulation. Subjects were randomly assigned to a control, stimulation (S), volitional exercise, or exercise combined with stimulation (ES) groups. Maximal voluntary isometric contraction and endurance data were recorded. In the three experimental groups, the number of repetitions and time of sustained contraction were increased by a predetermined amount during 4 weeks of training. The S and ES groups were stimulated using a biphasic, symmetrical pulse waveform having 200 microsec phase duration and 50 pulses per second. The ES group demonstrated the largest significant increases in abdominal strength, while the S group was the second best mode. No significant change in endurance occurred among the groups. Voltage and current increased significantly whereas tissue resistance decreased. It was concluded that combined exercise and stimulation may prove to be the most effective method of improving abdominal strength. J Orthop Sports Phys Ther 1987;8(12):567-573.
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... There are conflicting results regarding the effects of NMES on the abdominal musculature. Many studies have demonstrated significant improvements in abdominal strength and endurance, perceived muscle tone, and body satisfaction following NMES training (Alon et al., 1987;Alon et al., 1992, Abendroth-Smith & Sword, 1977Anderson et al., 2006, Ballantyne & Donne, 1999Porcari et al., 2005), while others have shown no improvement in these parameters (Aikman, et al., 1985;Porcari et al., 2002). ...
... The present study found 19% and 29% gains in abdominal strength after 4 and 6 weeks of high intensity stimulation, respectively. These results are in line with results from other studies that have used EMS to stimulate the abdominal musculature (Alon et al., 1987;Alon et al., 1992;Ballantyne & Donne, 1999). The results of Alon et al. (1987) and Alon et al. (1992) are virtually identical to those of the current study, as they found increase of 20.8% and 19.6%, respectively, after 4 weeks of EMS training. ...
... These results are in line with results from other studies that have used EMS to stimulate the abdominal musculature (Alon et al., 1987;Alon et al., 1992;Ballantyne & Donne, 1999). The results of Alon et al. (1987) and Alon et al. (1992) are virtually identical to those of the current study, as they found increase of 20.8% and 19.6%, respectively, after 4 weeks of EMS training. Since Alon's studies were both 4 weeks in duration, comparisons beyond that point are not possible. ...
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Background: Neuromuscular electrical stimulation (NMES) has been used clinically for many years as a modality to improve muscular strength and endurance. Recently, equipment manufacturers have developed over-the-counter NMES units to target specific muscle groups, particularly the abdominal region. Objective: To study the effects of self-administered neuromuscular electrical stimulation (NMES) on changes in abdominal muscle strength and endurance, core strength, abdominal girth, and subjective measures of body satisfaction and shape. Methods: Fifty-three adults were randomly assigned into high intensity (HI: n=27) or low intensity (LI: n=26) groups. The NMES device for the LI group had been altered so that subjects felt some tactile sensation, but the intensity was not sufficient to elicit a muscular contraction. All subjects stimulated their abdominal muscles 5 days per week (30 minutes per session) for 6 weeks. Subjects were tested at Baseline, 2, 4, and 6 weeks. Results: The HI group had a significantly greater increase in strength at 4 weeks (19%) and 6 weeks (29%) compared to the LI group and performed significantly more curl-ups than the LI group at 2 weeks (62%). Both groups had a significant increase in core strength over the course of the study, with no difference between groups. There was no change in abdominal girth between groups. Both groups had significant improvements in body satisfaction from Baseline to 4 weeks and Baseline to 6 weeks, with no significant interaction. Conclusions: Results of the current study indicate that high intensity NMES can significantly increase abdominal strength and endurance compared to LI intensity (control) stimulation. Results for subjective measures tended to favor the HI group, but were less conclusive, since the LI group also had some positive changes.
... There are a few studies that investigate the effect of NMES on abdominal muscles. Alon and colleagues [20][21][22], who were pioneers in this research, found that NMES to the abdominal musculature was well tolerated and strengthened muscles by about 14% to 22%. But these trials were on normal healthy subjects; as far as we know, there was no trial applied on DRAM. ...
... Another found that NMES alone increased muscle strength, but NMES plus exercise training did not [33]. Nevertheless, our result, supported by research on healthy subjects with NMES included in the abdominal training, showed that NMES combined with voluntary exercise could be more effective than exercise alone [20,22,31,34]. This shows the need for more research on DRAM. ...
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Objective To assess the effect of neuromuscular electrical stimulation (NMES) on the recovery of abdominal muscle strength in postnatal women with diastasis of recti abdominis muscles (DRAM). Methods Sixty women, 2 months postnatal, participated in this study. They were divided randomly into two equal groups. Group A received NMES in addition to abdominal exercises; group B received only abdominal exercises. The intervention in both groups was for three times per week for 8 weeks. The outcome measures were body mass index (BMI), waist/hip ratio, inter recti distance (IRD), and abdominal muscle strength in terms of peak torque, maximum repetition total work, and average power. Results Both groups showed highly significant (p<0.05) improvement in all outcomes. Further, intergroup comparisons showed significant improvement (p<0.05) in all parameters in favor of group A, except for the BMI. Conclusion NMES helps reduce DRAM in postnatal women; if combined with abdominal exercises, it can augment the effects.
... Regarding the abdominal muscles, previous studies investigated the effects of ST on their isometric strength and endurance. 26 Strength programs that focus on trunk stabilization strengthen the abdominal muscles, improve motor control, and decrease low back pain. [27][28][29] The abdominal muscles involved in trunk stabilization include the transverse abdominal (TrA) and internal oblique (IO) muscles, whereas the external oblique and rectus abdominis (RA) muscles mainly contribute to lumbopelvic control (LC). ...
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Context: Electrical muscle stimulation (EMS) was designed for artificial muscle activation or superimposed training. Objectives: To compare the effects of 8 weeks of superimposed technique (ST; application of electrical stimulation during a voluntary muscle action) and EMS on the cross-sectional area of the rectus abdominis, lateral abdominal wall, and on lumbopelvic control. Setting: University research laboratory. Design: Randomized controlled trial. Participants: Fifty healthy subjects were recruited and randomly assigned to either the ST or EMS group. Intervention: The participants engaged with the electrical stimulation techniques (ST or EMS) for 8 weeks. Main outcome measures: In all participants, the cross-sectional area of the rectus abdominis and lateral abdominal wall was measured by magnetic resonance imaging and lumbopelvic control, quantified using the single-leg and double-leg lowering tests. Results: There were no significant differences in the cross-sectional area of the rectus abdominis (right: P = .70, left: P = .99) or lateral abdominal wall (right: P = .07, left: P = .69) between groups. There was a significant difference between groups in the double-leg lowering test (P = .03), but not in the single-leg lowering test (P = .88). There were significant differences between the preintervention and postintervention in the single-leg (P < .001) and double-leg lowering tests (P < .001). Conclusions: ST could improve lumbopelvic control in the context of athletic training and fitness.
... The selected levels were near the limit of the device during the first week of the training period. This was inconsistent with earlier reports that showed a gradual increase of the maximal tolerable level of NMES during training periods [8,33]. It is possible that the limit level of the device used in the present study may not have reached the actual maximum tolerable stimulation of the participants. ...
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The purpose of this study was to examine the effects of neuromuscular electrical stimulation training for 12 weeks on the abdominal muscle size in trained athletes. Male collegiate track and field athletes participated in the present study and were randomly allocated to either training or control groups. Eleven participants of the training group completed a 60-session training program over a 12-week period (23 min/session, 5 days/week) involving neuromuscular electrical stimulation (mostly 20 Hz) for the abdominal muscles in addition to their usual training for the own events. The participants of the control group (n = 13) continued their usual training. Before and after the intervention period, cross-sectional areas of the rectus abdominis and abdominal oblique muscles (the internal and external obliques and transversus abdominis) and subcutaneous fat thickness were measured with magnetic resonance and ultrasound imaging. There were no significant changes in cross-sectional area of the rectus abdominis or abdominal oblique muscles or in subcutaneous fat thickness in the training or control groups after the intervention period. The change in cross-sectional area of the rectus abdominis in each participant was not significantly correlated with pre-training cross-sectional area and neither was the mean value of fat thickness at pre- and post-training. These results suggest that low-frequency (20 Hz) neuromuscular electrical stimulation training for 12 weeks is ineffective in inducing hypertrophy of the abdominal muscles in trained athletes, even when they have a thin layer of subcutaneous fat.
... It ameliorates muscle atrophy and weakness secondary to immobilization by preventing the decline in muscle protein synthesis, and improves the muscle strength via somatosensory stimulation that increases cortical excitability [18,19]. Several studies have shown that NMES combined with core strengthening exercise yields better rehabilitative effects than NMES or strengthening exercise alone [6,20,21]. ...
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Objective: To compare the effects of neuromuscular electrical stimulation (NMES) to abdominal muscles and back muscles on postural balance in post-stroke hemiplegic patients. Methods: Thirty post-stroke hemiplegic patients were prospectively enrolled and randomly assigned to one of the three groups: core muscle-strengthening exercise (CME) with NMES to abdominal muscles (group A), CME with NMES to back muscles (group B), and CME alone (group C). All subjects underwent their targeted interventions for 30 minutes each day, 5 days per week for 3 weeks under a conventional stroke rehabilitation program. Subjects were evaluated using Korean version of Berg Balance Scale (K-BBS), Trunk Impairment Scale (TIS), Korean version of Modified Barthel Index (K-MBI), Weight Distribution Index (WDI), and Stability Index (SI) just before and 3 weeks after intervention. Results: Changes in K-BBS (p<0.05) and TIS (p<0.05) were significantly higher in group A (18.5±8.10, 6.6±1.90) and group B (19.9±5.44, 7.0±2.26) than in group C (8.4±4.14, 3.1±0.99). However, K-MBI, WDI, and SI failed to show any significant difference. No significant difference in all outcomes was observed between groups A and B. Conclusion: The effect of NMES to the abdominal muscles was similar to the effect on back muscles in terms of postural balance. This finding indicated that the NMES to the abdominal muscles may be an alternative for post-stroke hemiplegic patients contraindicated for NMES to the back muscles. Additional studies investigating the effects of NMES on abdominal and back muscles are needed.
... Also, the evaluation of endurance for commonly-used muscles such as the quadriceps in normally functioning people may not be optimal as it likely suffers from ceiling effects. This suggestion is confirmed by the observation that high-frequency NMES training of abdominal muscles in healthy individuals resulted in substantial increases in abdominal strength and endurance time (Alon et al., 1987). ...
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Various electrical stimulation modalities are used as adjuvants to conventional training and rehabilitation programs to increase bodily function or to reduce symptoms, such as pain. One of these modalities, neuromuscular electrical stimulation (NMES), commonly refers to the transcutaneous application of electrical currents to a target muscle group with the objective to depolarize motor neurons and consequently elicit skeletal muscle contractions of substantial intensity (usually ranging from 10 to 60% of the maximal voluntary contraction). Because NMES can generate considerable muscle tension, it is frequently used as a strength training technique for healthy adults and athletes, but also as a rehabilitation tool to increase or preserve muscle function and mass in individuals with muscle weakness or patients who cannot perform voluntary contractions [e.g., patients suffering from chronic heart failure (CHF), chronic obstructive pulmonary disease (COPD), or critical illness; for reviews, see Roig and Reid, 2009; Sillen et al., 2009; Sbruzzi et al., 2010; Maddocks et al., 2011; Maffiuletti et al., 2011; Smart et al., 2013; Burke et al., 2016]. Under certain conditions, NMES training may also improve muscle oxidative capacity and result in a fast-to-slow muscle fiber type transition (Perez et al., 2002; Gondin et al., 2011a), which could potentially enhance endurance performance. However, the relevance of such adaptations in skeletal muscle tissue for the translation to functional performance that is particularly important for sport and daily activities is not always self-evident, mainly because of the heterogeneity in study populations, NMES parameters, and outcome measures. Unfortunately, the bodies of literature that either focus on mechanistic (i.e., muscle endurance) or clinical (i.e., functional endurance) outcomes are often too disconnected. In this opinion paper, we aim to bring these bodies of literature together and discuss the impact of high- vs. low-frequency NMES training on muscle vs. functional endurance in healthy vs. clinical populations. As such, we focus on human studies that chronically applied NMES for at least 3 weeks in healthy persons and patients, and distinguish between the effectiveness of non-tetanic low-frequency NMES (that is usually administered continuously at frequencies close to 10 Hz) and tetanic high-frequency NMES (that is usually administered intermittently at frequencies close to 50 Hz) on muscle endurance and functional endurance. For clarity purposes, we refer to muscle endurance as the exercise-induced decline in voluntary or electrically-evoked force (Duchateau and Hainaut, 1988; Gondin et al., 2006) or the endurance time of a sustained single-joint contraction (Gondin et al., 2006). In contrast, we refer to functional endurance as the maximal oxygen consumption or workload (Perez et al., 2002; Porcelli et al., 2012), the distance covered in a given time (e.g., 6-minute walk test) or the endurance time (Kim et al., 1995) for whole-body exercises such as walking and cycling. In the last section, we will provide some recommendations for better clinical use of NMES, and suggest potential directions for future research.
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The field of non-invasive body shaping has long been represented solely by fat reducing technologies, and the condition of the underlying muscles could be altered only by physical exercise. In 2018, high-intensity focused electromagnetic (HIFEM) technology was introduced to simultaneously tone and strengthen muscle and reduce fat. The technology is based on delivering focused electromagnetic fields into the treatment area, causing supramaximal muscle contractions. Clinical studies showed a significant reduction in subcutaneous white adipose tissue (sWAT) and an increase in muscle thickness (e.g., abdominal muscle) after a series of HIFEM treatments. The effect on both types of tissue was also confirmed by histological studies and was present in all imaging techniques (ultrasonography, magnetic resonance imaging, computed tomography). With an effect of this kind, HIFEM technology has opened up a completely new segment in body contouring.
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Background: Neuromuscular electrical stimulation (NMES) devices for abdominal muscles are being marketed to the general public to improve physical appearance. Abdominal muscles play an important role in lumbopelvic stability for optimizing performance. We investigated the effects of NMES training of abdominal muscles on muscle size, muscle strength, endurance, and lumbopelvic stability. Methods: Twenty-three subjects (12 females, 11 males) performed abdominal muscle NMES training for 8 weeks. Before and after NMES training, we measured muscle size (cross-sectional area [CSA] of the rectus abdominals [RA] and lateral abdominal wall [LAW]) by magnetic resonance imaging, muscle strength (trunk flexor and side bridge strength), endurance (trunk flexor and side bridge endurance time), and lumbopelvic stability (one-leg loading test). Results: There were significant increases between pre- and post-NMES training differences in the size (CSA of RA 21.7-25.4%, P<0.001; CSA of LAW 9.00-9.71%, P<0.001), strength (trunk flexor 14.9%, P<0.05; side bridge 33.7-53.6%, P<0.05), and endurance (trunk flexor 29.1%, P<0.05; side bridge 24.6-28.9%, P<0.05) of abdominal muscles and lumbopelvic stability (37.2-37.4%, P<0.05). Conclusions: NMES training could be applied to increase muscle size and muscle performances of abdominal muscles in sports and fitness fields.
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The known effects of Neuromuscular Electrical Stimulation (NMES) in Sports and Physical Medicine and Rehabilitation are presented in a review of literature. Influences of NMES on strength, endurance, neural adaptations, therapy of edema and pain as well as functional improvements will be focused on. Basics of physiology and histology in human muscle tissues are discussed in depth as well as elementary knowledge of NMES derived from animal studies. The central topic of this review is the influence of NMES on human skeletal muscle regarding histological changes, fiber transformation as well as strength and endurance of muscles involved. We optimized NMES characteristics and then conducted a series of investigations with 9 volunteers that had 30 minutes of NMES applied twice daily for 7 weeks. Muscle biopsies were taken from the vastus lateralis portion of quadriceps femoris muscle on both the stimulated and no stimulated leg before and after the 7 week NMES period. Additionally participants performed isometric strength measurements of quadriceps femoris muscle at different knee joint angles before and after the 7 week stimulation period. Biopsies from the no stimulated side showed no significant changes and may therefore serve as proof for the quality of the biopsies and as a standard for comparison. The increment of type IIa fiber volume was 12.3% and of type IIa fiber number 16%, respectively. Volume density of intermyofibrillar mitochondria increased by 22%. Subsarcolemmal mitochondria remained unchanged which contrasts the effects seen in voluntary non-NMES muscle training. Capillary density was augmented by 14.58%. NMES is an appropriate means of adjusting longstanding muscle dysbalance regarding strength, endurance and improving oxidative metabolism in human skeletal muscle. Daily muscle fiber workload (i.e. number of stimuli per day) was found to be the main determinant of fiber transformation.
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The aim of the present study was to investigate the effects of a multiple set squat exercise training intervention with superimposed electromyostimulation (EMS) on strength and power, sprint and jump performance. Twenty athletes from different disciplines participated and were divided into two groups: strength training (S) or strength training with superimposed EMS (S+E). Both groups completed the same training program twice a week over a six week period consisting of four sets of the 10 repetition maximum of back squats. Additionally, the S+E group had EMS superimposed to the squat exercise with simultaneous stimulation of leg and trunk muscles. EMS intensity was adjusted to 70% of individual pain threshold to ensure dynamic movement. Strength and power of different muscle groups, sprint, and vertical jump performance were assessed one week before (pre), one week after (post) and three weeks (re) following the training period. Both groups showed improvements in leg press strength and power, countermovement and squat jump performance and pendulum sprint (p < 0.05), with no changes for linear sprint. Differences between groups were only evident at the leg curl machine with greater improvements for the S+E group (p < 0.05). Common squat exercise training and squat exercise with superimposed EMS improves maximum strength and power, as well as jumping abilities in athletes from different disciplines. The greater improvements in strength performance of leg curl muscles caused by superimposed EMS with improvements in strength of antagonistic hamstrings in the S+E group are suggesting the potential of EMS to unloaded (antagonistic) muscle groups.
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Immobilization of the knee after anterior cruciate ligament (ACL) reconstruction results in marked thigh atrophy and decrease in quadriceps strength that may prolong the rehabilitation program of the injured athlete. Fifteen male volunteers undergoing ACL reconstruction were divided into two groups, stimulation (during immobilization) and nonstimulation. Measurements of thigh circumference and isometric quadriceps strength were tested preoperatively, immediately after cessation of cast immobilization (6 weeks), and at 9 and 12 weeks postoperatively. The changes in circumference and strength between the first preoperative test and all subsequent tests were compared for statistical significance (Student's t-test, P less than 0.5) between the two groups. The decrease in quadriceps strength of the stimulation group during immobilization was significantly less than that of the nonstimulation group, although later differences between the two groups were not significant. There were no significant differences in thigh atrophy between the two groups. In conclusion, isometric quadriceps torque decreases resulting from immobilization can be significantly lessened by application of electrical stimulation during immobilization. Electrical stimulation to the quadriceps does not significantly alter thigh circumference changes that occur during immobilization.
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A clinical study of six individuals was set up to compare an Electro-Myo stimulation protocol to an isokinetic protocol. The objective of the study was to see which was more effective in increasing power in the knee extensor mechanism. Results of the study showed that isokinetics were superior to Electro-Myo stimulation in increasing power. One question that remained unanswered in the testing was whether a higher faradic current, if tolerated, would be more efficient in increasing the power of a muscle group than would isokinetics.
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Following surgery or injury to the knee, 35 patients were referred for physiotherapy, with requests to increase quadriceps strength. They were divided into 2 groups in order to study the effectiveness of electro-stimulation as a mode of treatment. One group was treated in a normal isometric quadriceps program; the other group was treated with a program of tetanizing electrical stimulation in a double blind study. All patients were tested before treatment and after the completion of 12 treatments. It was observed that a program of electrical stimulation is as effective as a program of isometric quadriceps strengthening for development of muscle power.
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A study of 50 patients with chondromalacia patellae was undertaken at the Sports Medicine Clinic, Carleton University, Ottawa. All of the patients demonstrated a significant degree of atrophy of the quadriceps, functional disability and varying intensities of pain. The patients were subjected to a course of faradic stimulation of the quadriceps muscle group. Twenty treatments were given, each one consisting of ten 10-second maximal tetanic contractions with a 50-second rest period between each. An increase in quadriceps strength ranging from 25.3% in the mild chondromalacia patellae group to a 200% increase in the severe group was documented. Quadriceps girth increased an average of 5.1%. The results were directly proportional to the frequency of the treatment and the amperage tolerated by the patient. It was concluded that faradic stimulation is a useful tool in the treatment of chondromalacia patellae where significant quadriceps atrophy is present.
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A clinical study of six individuals was set up to compare an Electro-Myo stimulation protocol to an isokinetic protocol. The objective of the study was to see which was more effective in increasing power in the knee extensor mechanism. Results of the study showed that isokinetics were superior to Electro-Myo stimulation in increasing power. One question that remained unanswered in the testing was whether a higher faradic current, if tolerated, would be more efficient in increasing the power of a muscle group than would isokinetics. J Orthop Sports Phys Ther 1980;2(1):20-24.
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Eight patients undergoing reconstruction of the anterior cruciate ligament were randomly allocated into two groups. The control group received a standard plaster cast and isometric muscle training. The stimulated group received a standard plaster cast, isometric training, and percutaneous electrical stimulation during the recovery period. The patients were examined clinically and with repeated muscle biopsies before surgery, 1 week after surgery, and 5 weeks after surgery at the time of removal of the cast. The electrically stimulated group had better muscle function from a clinical point of view and their succinate dehydrogenase activities were significantly higher than those in the control group. Electrical stimulation thus could prevent the fall in oxidative enzyme activity which was noted in the control group. The results suggest that percutaneous electrical stimulation may be a way of preventing muscle atrophy after major knee ligament surgery in athletes.
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Thirty-seven healthy subjects took part in an investigation to determine if the application of electrical stimulation to normal muscle, in combination with exercise, augments strength. Subjects were divided into three groups. Grwoup A (n = 14) was a control group (no exercise, no electrical stimulation). Group B members (n = 11) engaged in 10 sessions of maximum isometric exercise, and Group C subjects (n = 12) performed 10 sessions of maximum isometric exercise while simultaneously receiving electrical stimulation. The knee extensor muscles of subjects in Groups B and C increased in strength. However, the strength gains for Groups B and C were equivalent, suggesting that electrical stimulation combined with maximum isometric contractions has no greater effect on enhancing strength than does conventional static exercise.
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The purpose of this investigation was to determine if training isometrically with electrical stimulation (ES) alone would significantly increase isometric strength of the quadriceps femoris muscle. The relationships between the strength changes and the relative force and duration of training contractions were also studied. An experimental group (Group 1) and a control group (Group 2), 12 subjects in each, underwent pretesting and posttesting to obtain their maximum voluntary isometric contractions (MVICs). Group 1 trained with maximally tolerable isometric contractions induced by ES, three days a week for four weeks. Results showed that although both groups demonstrated increases in isometric strength of their quadriceps femoris muscles, training isometrically with ES produced a significantly greater increase (p less than .01) than not training with ES. The relative strength improvement in Group 1 was positively and significantly correlated with training-contraction intensity and duration. The relative increase in isometric strength, using only ES, may be determined by the ability of the subjects to tolerate longer and more forceful contractions. Suggestions for further research and implications for the clinical use of ES for strength-training are discussed.
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The purpose of this study was to examine the effectiveness of an electronic muscle stimulator in strengthening normal quadriceps femoris muscle without the assistance of simultaneous isometric muscle contraction. The sample consisted of 58 subjects who were randomly divided into three independent groups. One group (n = 19) served as controls; one group (n = 20) underwent daily stimulation of the right quadriceps femoris muscle using a specified protocol; and one group (n = 19) underwent isometric strengthening of the quadriceps femoris muscle using a specified protocol. The mechanical force of isometric quadriceps femoris muscle contraction was recorded weekly for the three groups, and the initial and final values were subjected to an analysis of covariance. The electrical-stimulation and isometric-exercise groups had statistically significant increases in quadriceps femoris muscle torque when compared with the nonexercised controls (p less than .001). The data supported the use of this electronic stimulator as an appropriate device for strengthening skeletal muscle without voluntary effort.