Electromyographical analysis and comparison of selected abdominal training devices with a traditional crunch

The present study compared the muscle activity elicited by selected abdominal training devices with muscle activity elicited by a traditional crunch. Forty-six adults participated in the study. The exercise devices tested included the Ab-ONE, Perfect Abs Roller, Ab Scissor, Ab Swing, 6SecondAbs, and the Torso Track. For those devices with variable resistances, all were tested at their high resistance setting. Surface electromyography (EMG) was recorded from the upper and lower portions of the rectus abdominis and the external oblique during each repetition. EMG values were analyzed using repeated measures analyses of variance (ANOVA) and pairwise comparisons. EMG measurements for each abdominal muscle analyzed were highly reliable and differed significantly across the exercises tested. Muscle activity for the upper and lower portions of the rectus abdominis for a normal crunch was lower than for the Ab-ONE, the same as for the Perfect Abs Roller, and higher than for the Ab Scissor, Ab Swing, 6SecondAbs, and Torso Track. External oblique muscle activity for a traditional crunch was higher than for the Perfect Abs Roller and did not differ from the other devices. These results support previous findings that portable abdominal devices are most effective if they not only mimic the mechanics of a traditional crunch, but also provide external resistance to increase involvement of the abdominal musculature.     

Electromyographic analysis of abdominal muscle activity using portable abdominal exercise devices and a traditional crunch

The purpose of this study was to compare the abdominal muscle activity elicited while using 4 portable abdominal training devices vs. a traditional crunch. Thirty-three adults participated in this study. The exercise devices tested included the Ab Roller Plus, Torso Track 2, AB-DOer Pro, and the Perfect Abs. All subjects were tested on the Perfect Abs in both a seated and supine position using low-, medium-, and high-resistance bands. The Torso Track 2 was also tested at low- and high-resistance settings. Surface electromyography (EMG) was recorded from the upper and lower portions of the rectus abdominis, external oblique, and the rectus femoris during each repetition. Statistical analyses were performed on the mean EMG values using a repeated analysis of variance (ANOVA) procedure. There was no significant difference in abdominal muscle activity between the Ab Roller Plus, the Torso Track 2 (high resistance), and a traditional crunch. The mean abdominal muscle activity was significantly lower than a normal crunch, however, when using the AB-DOer, Torso Track (low resistance), and the Perfect Abs seated with the low-resistance band. In contrast, the Perfect Abs, when used in the supine position with the medium- and high-resistance bands, elicited significantly greater mean abdominal muscle activity than a crunch. Of the 4 devices tested, only the Perfect Abs when used in the supine position with the medium- and high-resistance bands, elicited more abdominal activity than a crunch. The results suggest that portable abdominal devices are most effective if they not only mimic the mechanics of a traditional crunch, but also provide external resistance to increase the involvement of the abdominal musculature.     

Electromyographic comparison of the ab-slide and crunch exercises

The purpose of this study was to compare the Ab-Slide with crunch abdominal exercises for electromyographic activity for selected muscles. Forty-five subjects who regularly performed abdominal exercises participated. Subjects completed 5 trials for each exercise, with repetition rate controlled by the tester. Electromyographic activity for the external oblique (EO), upper rectus abdominis (URA), and lower rectus abdominis (LRA) was collected. Raw data for each muscle were rectified and integrated over 100-millisecond time intervals. For each muscle, the average concentric and eccentric integrated amplitudes of the middle 3 trials were compared with a dependent t-test. During concentric movement, the EO and LRA had significantly higher integrated activation amplitudes for the crunch exercise. During the eccentric movement, the URA, LRA, and EO had significantly higher average integrated activation amplitudes for the Ab-Slide exercise. The Ab-Slide is a credible abdominal exercise variation, but the crunch should remain the standard abdominal exercise.     

Electromyographic activity of the rectus abdominis during a traditional crunch and the basic jackknife exercise with the Ab Lounge™

The use of nontraditional exercise devices such as the Ab Lounge? has been promoted as being as effective as the traditional abdominal crunch in strengthening the abdominal musculature. Evidence for this is lacking, however. The purpose of this study was to compare the degree of activation of the upper and lower rectus abdominis using electromyography (EMG) during a traditional crunch with the basic jackknife using the Ab Lounge?. Twenty-two subjects (6 men and 16 women) were randomly selected from the student population at the University of the West Indies (Mona Campus). The mean age of the participants was 20.5 ± 1.5 years, height 166.4 ± 6.2 cm, weight 64 ± 10.3 kg, and waist-hip ratio 0.7 ± 0.1. Surface EMG was used to assess the muscle activity from the upper and lower rectus abdominis while each exercise was performed. The EMG data were full-wave rectified and normalized using a mathematical model that was set up in Microsoft Excel for Windows XP. Statistical analysis was performed on the data using a univariate analysis of variance with gender as a covariate. Significance was determined by p < 0.05. The mean EMG data recorded for the upper rectus abdominis was significantly higher with the traditional crunch when compared with the basic jackknife performed on the Ab Lounge? (F = 4.39, p = 0.04). The traditional crunch produced a higher level of activity in the lower rectus abdominis when compared with the basic jackknife, but this was not statistically significant (F = 0.249, p = 0.62). There was no significant interaction between gender and the effect of the type of exercise on upper and lower rectus abdominis activation. These results suggest that the traditional abdominal crunch is more effective than the basic jackknife is in activating the rectus abdominis musculature.     

Electromyographic response of the abdominal musculature to varying abdominal exercises

This study examined the electromyographic (EMG) response of the upper rectus abdominis (URA), lower rectus abdominis (LRA), internal obliques (IOs), external obliques (EOs), and the rectus femoris (RF) during various abdominal exercises (crunch, supine V-up, prone V-up on ball, prone V-up on slide board, prone V-up on TRX, and prone V-up on Power Wheel). The subjects (n = 21) performed an isometric contraction of the abdominal musculature while performing these exercises. Testing revealed no statistically significant differences between any of the exercises with respect to the EOs, the URA, or the LRA. However, when examining the IO muscle, the supine V-up exercise displayed significantly greater muscle activity than did the slide exercise. In addition, EMG activity of the RF during the crunch was significantly less than in any of the other 5 exercises. These results indicate that when performing isometric abdominal exercises, non-equipment-based exercises stressed the abdominal muscles similarly to equipment-based exercises. Based on the findings of the current study, the benefit of training the abdominal musculature in an isometric fashion using commercial equipment could be called into question.     

The effect of posture on respiratory activity of the abdominal muscles

The purpose of this study was to determine the influence of posture on the expiratory activity of the abdominal muscles. Fifteen young adult men participated in the study. Activities of the external oblique abdominis, internal oblique abdominis, and rectus abdominis muscles were measured electromyographically in various postures. We used a pressure threshold in order to activate the abdominal muscles as these muscles are silent at rest. A spirometer was used to measure the lung volume in various postures. Subjects were placed in the supine, standing, sitting, and sitting-with-elbow-on-the-knee (SEK) positions. Electromyographic activity and mouth pressure were measured during spontaneous breathing and maximal voluntary ventilation under the respiratory load. We observed that the lung volume changed with posture; however, the breathing pattern under respiratory load did not change. During maximal voluntary ventilation, internal oblique abdominis muscle expiratory activity was lower in the SEK position than in any other position, external oblique abdominis muscle inspiratory activity was lower in the supine position than in any other position, and internal oblique abdominis muscle activity was higher in the standing position than in any other position. During spontaneous breathing, external oblique abdominis muscle activity was higher during expiration and inspiration in the SEK position than in any other position. The internal oblique abdominis muscle activity was higher during both inspiration and expiration in the standing position than in any other position. The rectus abdominis muscle activity did not change with changes in posture during both inspiration and expiration. Increase in the external oblique abdominis activity in the SEK position was due to anatomical muscle arrangement that was consistent with the direction of lower rib movement. On the other hand, increase in the internal oblique abdominis activity in the standing position was due to stretching of the abdominal wall by the viscera. We concluded that differences in activity were due to differences in the anatomy of the abdominal muscles and the influence of gravity.     

An electromyographic analysis of the Ab-Slide exercise, abdominal crunch, supine double leg thrust, and side bridge in healthy young adults: implications for rehabilitation professionals

The purpose of this study was to examine the effectiveness of a commercial abdominal machine (Ab-Slide) and three common abdominal strengthening exercises (abdominal crunch, supine double leg thrust, and side bridge) on activating abdominal and minimizing extraneous (nonabdominal) musculature-namely, the rectus femoris muscle. We recruited 10 males and 12 females whose mean (+/- SD) percent body fat was 10.7 +/- 4 and 20.7% +/- 3.2%, respectively. Electromyographic (EMG) data were recorded using surface electrodes for the rectus abdominis, external oblique, internal oblique, and rectus femoris. We recorded peak EMG activity for each muscle during each of the four exercises and normalized the EMG values by maximum muscle contractions (% MVIC). A two-factor repeated-measures analysis of variance assessed differences in normalized EMG activity among the different exercise variations (p < 0.05). Post hoc analyses were performed using the Bonferroni-adjusted alpha to assess between-exercise pair comparisons (p < 0.002). Gender did not affect performance; hence, data were collapsed across gender. We found a muscle x exercise interaction (F9,189 = 5.2, p < 0.001). Post hoc analyses revealed six pairwise differences. The Ab-Slide elicited the greatest EMG activity for the abdominal muscles and the least for the rectus femoris. The supine double leg thrust could be a problem for patients with low-back pathology due to high rectus femoris muscle activity.     

Transversus abdominis muscle function in humans

We used a high-resolution ultrasound to make electrical recordings from the transversus abdominis muscle in humans. The behavior of this muscle was then compared with that of the external oblique and rectus abdominis in six normal subjects in the seated posture. During voluntary efforts such as expiration from functional residual capacity, speaking, expulsive maneuvers, and isovolume "belly-in" maneuvers, the transversus in general contracted together with the external oblique and the rectus abdominis. In contrast, during hyperoxic hypercapnia, all subjects had phasic expiratory activity in the transversus at ventilations between 10 and 18 l/min, well before activity could be recorded from either the external oblique or the rectus abdominis. Similarly, inspiratory elastic loading evoked transversus expiratory activity in all subjects but external oblique activity in only one subject and rectus abdominis activity in only two subjects. We thus conclude that in humans 1) the transversus abdominis is recruited preferentially to the superficial muscle layer of the abdominal wall during breathing and 2) the threshold for abdominal muscle recruitment during expiration is substantially lower than conventionally thought.     

Effect of hypercapnia and PEEP on expiratory muscle EMG and shortening

The present study examined the effects of hypercapnia and positive end-expiratory pressure (PEEP) on the electromyographic (EMG) activity and tidal length changes of the expiratory muscles in 12 anesthetized, spontaneously breathing dogs. The integrated EMG activity of both abdominal (external oblique, internal oblique, rectus abdominis, and transverse abdominis) and thoracic (triangularis sterni, internal intercostal) expiratory muscles increased linearly with increasing PCO2 and PEEP. However, with both hypercapnia and PEEP, the percent increase in abdominal muscle electrical activity exceeded that of thoracic expiratory muscle activity. Both hypercapnia and PEEP increased the tidal shortening of the external oblique and rectus abdominis muscles. Changes in tidal length correlated closely with simultaneous increases in muscle electrical activity. However, during both hypercapnia and PEEP, length changes of the external oblique were significantly greater than those of the rectus abdominis. We conclude that both progressive hypercapnia and PEEP increase the electrical activity of all expiratory muscles and augment their tidal shortening but produce quantitatively different responses in the several expiratory muscles.     

Shoulder muscle EMG activity during push up variations on and off a Swiss ball

Background

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.

Methods

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.

Results and discussion

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.

Conclusion

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.

     

A comparison of trunk muscle activation: Ab Circle vs. traditional modalities

The purpose of this study was to compare the activation of the rectus abdominis (RA), external oblique abdominis (EO), lower abdominal stabilizers (LASs), and lumbar erector spinae (LES) during performance of 3 traditional trunk exercises vs. exercise on the Ab Circle device. Surface electromyography was used to assess 12 subjects (6 men, 6 women) for 6 exercise conditions, including: abdominal crunch, side bridge, quadruped, and Ab Circle levels 1-3. For the RA, the abdominal crunch elicited significantly greater activity vs. the Ab Circle level 1, and the side bridge elicited significantly greater activity vs. the Ab Circle levels 1 and 2. For the EO, the side bridge elicited significantly greater activity vs. the quadruped. No significant differences were noted between conditions for the LASs. For the LES, the side bridge and quadruped elicited significantly greater activity vs. the abdominal crunch. The results of this study indicate that the anterior, posterior, and lateral trunk musculature can be activated to similar or even greater levels by performing the 3 traditional trunk exercises vs. the Ab Circle. This was particularly evident for the side bridge exercise, which elicited significantly greater activity of the RA vs. the Ab Circle levels 1 and 2, and elicited similar activity of the EO, LASs, and LES at all 3 Ab Circle levels.     

Pattern of expiratory muscle activation during lower thoracic spinal cord stimulation.

Large positive airway pressures (Paws) can be generated by lower thoracic spinal cord stimulation (SCS), which may be a useful method of restoring cough in spinal cord-injured patients. Optimal electrode placement, however, requires an assessment of the pattern of current spread during SCS. Studies were performed in anesthetized dogs to assess the pattern of expiratory muscle recruitment during SCS applied at different spinal cord levels. A multicontact stimulating electrode was positioned over the surface of the lower thoracic and upper lumbar spinal cord. Recording electromyographic electrodes were placed at several locations in the abdominal and internal intercostal muscles. SCS was applied at each lead, in separate trials, with single shocks of 0.2-ms duration. The intensity of stimulation was adjusted to determine the threshold for development of the compound action potential at each electrode lead. The values of current threshold for activation of each muscle formed parabolas with minimum values at specific spinal root levels. The slopes of the parabolas were relatively steep, indicating that the threshold for muscle activation increases rapidly at more cephalad and caudal sites. These results were compared with the effectiveness of SCS (50 Hz; train duration, 1-2 s) at different spinal cord levels to produce changes in Paw. Stimulation at the T9 and T10 spinal cord level resulted in the largest positive Paws with a single lead. At these sites, threshold values for activation of the internal intercostal (7-11th interspaces) upper portions of external oblique, rectus abdominis, and transversus abdominis were near their minimum. Threshold values for activation of the caudal portions of the abdominal muscles were high (>50 mA). Our results indicate that 1) activation of the more cephalad portions of the abdominal muscles is more important than activation of caudal regions in the generation of positive Paws and 2) it is not possible to achieve complete activation of the expiratory muscles with a single electrode lead by using modest current levels. In support of this latter conclusion, a two-electrode lead system results in more uniform expiratory muscle activation and significantly greater changes in Paw.     

Electromyographic comparison of the upper and lower rectus abdominis during abdominal exercises

The objective of this pilot study was to determine the effect of 6 different abdominal exercises on the electrical activity of the upper rectus abdominis (URA) and lower rectus abdominis (LRA). Eight healthy, adult volunteers completed 6 random abdominal exercises: curl up, Sissel ball curl up, Ab Trainer curl up, leg lowering, Sissel ball roll out, and reverse curl up. Action potentials were recorded and analyzed from the URA and the LRA using surface electromyography (EMG) during a 2-second concentric contraction. The average normalized data were compared between the URA and the LRA in order to determine the behavior of the different muscle sites and between exercises in order to determine which exercises elicited the highest EMG activity. There were no significant differences (p > 0.05) between the EMG activity of the URA and LRA during any exercise. There were no significant interactions between subject and muscle site or between exercise and muscle site. Significant differences were found among the 6 exercises performed, and due to the interaction between subject and exercise performed. Both the URA and the LRA recorded significantly higher mean amplitudes during the Sissel ball curl up than during all other exercises. In addition, the curl up, Sissel ball curl up, and Ab Trainer curl up had significantly higher normalized EMG activity in both muscle sites than the reverse curl up, the leg lowering exercise, and the Sissel ball roll out. The curl up and the Ab Trainer curl up exercises were not significantly different in terms of their normalized EMG activities for both the URA and the LRA.     

The external oblique flap for reconstruction of the rectus sheath.

Despite the availability of synthetic materials and distant fascial flaps, primary closure of ventral abdominal defects with contiguous tissues remains the preferred solution. Increased experience with such defects in the lower abdomen, particularly at the time of bilateral rectus muscle transposition, led in 1985 to the investigation of an external oblique abdominis flap for closure of the anterior rectus sheath. From October of 1985 to October of 1990, 33 patients underwent repair of bilateral lower rectus abdominis defects with the help of bilateral external oblique flaps. Each of the patients had undergone synchronous chest or breast reconstruction using a transverse rectus abdominis musculocutaneous flap including bilateral rectus muscle pedicles. Although all patients in this study had undergone double-pedicle rectus muscle procedures, not all patients having had double-pedicle rectus muscle procedures required this maneuver. External oblique flaps were performed at the time of rectus sheath repair only if fascia could not be approximated without tearing. After closure of the bilateral paramedian defect, synthetic mesh overlay was added only if the direct closure still appeared excessively tight. At the time of advancement of the external oblique muscle and fascia, the internal oblique abdominis muscle and lateral cutaneous nerve of the thigh were preserved. Of the 33 patients who underwent this procedure, 7 required the addition of mesh overlay. Thirty-two patients healed uneventfully with a remarkably solid ventral abdominal wall. One patient developed an early postoperative hernia subsequent to a major and prolonged abdominal-wall infection and abscess. Patient follow-up ranged from 1 to 36 months, with a mean of 12 months.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electromyographic muscle activity in curl-up exercises with different positions of upper and lower extremities

The purpose of the study was to evaluate the electromyographic (EMG) activity of muscles in curl-up exercises depending on the position of the upper and lower extremities. From the perspective of biomechanics, different positions of the extremities result in shifting the center of gravity and changing muscular loads in abdominal strength exercises. The subjects of the research were 3 healthy students (body mass 53-56 kg and height 163-165 cm) with no history of low back pain or abdominal surgery. Subjects completed 18 trials for each of the 9 exercises (static curl-up with 3 positions of the upper and 3 position of the lower extremities). The same experiment with the same subjects was conducted on the next day. The EMG activity of rectus abdominis (RA), erector spinae (ES), and quadriceps femoris-long head (rectus femoris [RF]) was examined during the exercises. The surface electrical activity was recorded for the right and left sides of each muscle. The raw data for each muscle were rectified and integrated. The statistical analysis showed that changing the position of upper extremities in the examined exercises affects the EMG activity of RA and ES but does not significantly affect the EMG activity of RF. Additionally, it was found that curl-up exercises with the upper extremities extended behind the head and the lower extremities flexed at 90° in the hip and knee joints involve RA with the greatest intensity, whereas curl-up exercises with the upper extremities extended along the trunk and the lower extremities flexed at 90° in the hip and knee joints involve RA with the lowest intensity.     

Walking slope and heavy backpack loads affect torso muscle activity and kinematics

The independent effects of sloped walking or carrying a heavy backpack on posture and torso muscle activations have been reported. While the combined effects of sloped walking and backpack loads are known to be physically demanding, how back and abdominal muscles adapt to walking on slopes with heavy load is unclear. This study quantified three-dimensional pelvis and torso kinematics and muscle activity from longissimus, iliocostalis, rectus abdominis, and external oblique during walking on 0° and ± 10° degree slopes with and without backpack loads using two different backpack configurations (hip-belt assisted and shoulder-borne). Iliocostalis activity was greater during downhill and uphill compared to level walking, but longissimus was only greater during uphill. Rectus abdominis activity was greater during downhill and uphill compared to level, while external oblique activity decreased as slopes progressed from down to up. Longissimus, but not iliocostalis, activity was reduced during both backpack configurations compared to walking with no pack. Hip-belt assisted load carriage required less rectus abdominis activity compared to using shoulder-borne only backpacks; however, external oblique was not influenced by backpack condition. Our results revealed different responses between iliocostalis and longissimus, and between rectus abdominis and external obliques, suggesting different motor control strategies between anatomical planes.     

Abdominal muscle use during breathing in unanesthetized dogs

The pattern of abdominal muscle use during breathing in unanesthetized dogs is unknown. Therefore, we have recorded the electromyograms of the rectus abdominis, external oblique, and transversus abdominis in eight conscious animals breathing quietly in the sitting, standing, and prone postures. During quiet breathing in the sitting posture, all animals invariably had a large amount of phasic expiratory activity in the transversus abdominis. In contrast, only four animals showed some expiratory activity in the external oblique, and only one animal had expiratory activity in the rectus abdominis. A similar pattern was observed when the animals were standing or lying prone, although the amount of expiratory activity was less in this posture. Bilateral cervical vagotomy in four animals did not affect the degree of transversus abdominis expiratory activation or the influence of posture. We conclude that in conscious dogs 1) the abdominal muscles play an important role during breathing and make spontaneous quiet expiration a very active process, 2) the transversus abdominis is the primary respiratory muscle of the abdomen, and 3) unlike in anesthetized animals, extrapulmonary receptors play a major role in promoting abdominal expiratory contraction.     

Small intestinal submucosa in abdominal wall repair after TRAM flap harvesting in a rat model

The strength of porcine small intestinal submucosa in abdominal wall repair after transverse rectus abdominis myocutaneous flap harvesting was examined in a rat model. Changes in the levels of selected molecular markers of inflammation after small intestinal submucosa implantation were also studied. Eighty-three rats were divided into three groups. In experimental group I, an abdominal wall defect created by removal of the rectus abdominis muscle was repaired with placement of a 1.5 x 5-cm2 patch of small intestinal submucosa. In experimental group II, the muscle defect was repaired with a combination of small intestinal submucosa patch placement and fascial closure. In the control group, the defect was repaired with direct fascial closure. At postoperative times of 3 days, 2 weeks, 1 month, and 2 months, the muscle tissues adjacent to the abdominal wall repair site were subjected to biopsies for assessment of inflammation markers. Full-thickness sections of the abdominal wall from the repair site in each animal were removed for tensile strength testing and histological examinations. The results demonstrated that interleukin-6 and interferon-gamma levels were increased in the two experimental, small intestinal submucosa-treated groups at 3 days and 2 weeks postoperatively. The results of mechanical testing demonstrated that the average tensile strength of the repaired abdominal wall in the repair model with combined small intestinal submucosa placement and fascial repair was significantly greater than the values for repairs with fascial closure or small intestinal submucosa placement alone. The use of small intestinal submucosa placement in combination with fascial repair can significantly improve the strength of the repaired abdominal wall after transverse rectus abdominis myocutaneous flap harvesting.     

Difference in abdominal muscularity at the umbilicus level between young and middle-aged men

This study aimed to examine how the muscularity of the abdomen at the umbilicus level differs between sedentary middle-aged and young men. Magnetic resonance imaging was applied to determine the cross-sectional areas of skeletal muscle, subcutaneous fat, and interperitoneal tissue in 43 middle-aged (40 58yrs) and 38 young (21-29 yrs) men. The cross-sectional area of the skeletal muscle was analyzed as the sum of those of the rectus abdominis, abdominal oblique, lower back, and iliopsoas skeletal muscle groups. The middle-aged men showed greater waist circumference and whole abdominal cross-sectional area than the young men. In addition, the cross-sectional areas of subcutaneous fat and interperitoneal tissue were greater in the middle-aged men than in the young men. However, the total cross-sectional area of the skeletal muscle was similar between the two groups, although its percentage to the whole abdominal cross-sectional area was higher in the young men compared to the middle-aged men. Among the four skeletal muscle groups analyzed, the percentage of the cross-sectional areas in abdominal oblique muscles to that of total skeletal muscle was higher in the middle-aged men than in the young men and that of the lower back muscles was the reverse. These results were similar even when cross-sectional area data were analyzed using a subsample (33 middle-aged and 23 young men) matched for body height and mass. Thus, the present study indicated that the total muscularity of the abdomen at the umbilicus level was similar between the middle-aged and young men, but the relative distributions of lower back and abdominal oblique muscles varied between the two generations.     

Abdominal strengthening using the AbVice machine as measured by surface electromyographic activation levels

Twenty-four college students served as subjects in a study that examined the effect of a prototypical abdominal muscle strengthening device (AbVice) compared with other devices currently on the market. The purpose of the present study was to investigate a prototypical device (AbVice) that incorporates contraction of the hamstring and gluteal musculature in conjunction with the abdominals, which may assist in decreasing activation of the hip flexors by allowing greater activity levels of the abdominal musculature via the theory of reflex inhibition, compared with other devices currently available on the market (AbRoller and AbRocker). The repeated-measures study included 17 women and 7 men who ranged in age from 20-23 years (mean +/- SD age, 21.3 +/- 1.5 years). Each subject underwent a single session of data collection during which they completed 10 repetitions of abdominal crunches per device. Subjects completed 4 different crunch sets (AbRocker, AbRoller, standard crunch, AbVice). Counterbalancing of the device was used to negate the effect of fatigue. Speed of repetitions was ensured via use of a metronome set at 40 b.min(-1) to permit similar contraction times and rest periods between repetitions. Rest between conditions was 3 minutes. Mean activation levels of surface electromyography (EMG) were recorded for each condition at the following locations on the right side of the body: rectus abdominis 2.5 cm superior to the umbilicus, rectus abdominis 2.5 cm inferior to the umbilicus, external oblique abdominis 1.0 cm medial to the anterior superior iliac spine, and external oblique abdominis less than 1.0 cm superior to the inguinal ligament. Mean (SD) activation was 1,165.21 mV (634.60 mV) with the AbVice, 242.92 mV (263.03 mV) with the AbRocker, 753.29 mV (514.80 mV) with the standard crunch, and 757.67 mV (542.85 mV) with the AbRoller. Broken down by sex, women had the following mean (SD) EMG values: 1,079.76 mV (705.02 mV) with the AbVice, 680.35 mV (535.35 mV) with the standard crunch, 262.70 mV (305.89 mV) with the AbRocker, and 636.88 mV (502.82 mV) with the AbRoller. Men demonstrated mean (SD) values of 1,372 mV (383.87 mV) with the AbVice, 1,051 mV (560.09 mV) with the AbRoller, 930.43 mV (447.17 mV) with the standard crunch, and 194.86 mV (109.05 mV) with the AbRocker. Two-way analysis of variance with factor 1 (person) and factor 2 (condition) had F values of 11.73 and 36.04, respectively. Post hoc analysis using the Tukey test indicated that all comparisons between conditions were significant at the p = 0.01 level except for the standard crunch vs. the AbRoller. The AbVice activated the selected abdominal musculature more effectively than the other conditions.