Sex recognition and mate choice by male Bufo gargarizans in central China

Mate choice is important for successful reproduction, and consequently species have evolved various ways to choose potential high-quality mates. Anuran mate choice and underlying processes have been the subject of several recent investigations, however we are far from a complete understanding of mate choice in this system. In the present study, when given a simultaneous choice between a male and a female of identical size, males did not discriminate between the sexes, and attempted to clasp a male or a female with equal frequency. Test males only released the stimulus toad when a release call was emitted by the stimulus male. When two males with distinct size differences were provided with a male, the male chose the larger one. Moreover, males discriminated between gravid females that differed in body size, choosing larger gravid females over smaller ones. These results suggest that male Bufo gargarizans can discriminate between the sexes, probably based on male release calls, and prefer to mate with larger individual using visual cues.     

Importance of pause between spider courtship vibrations and general problems using synthetic stimuli in behavioural studies

Effectiveness of natural stimuli (recorded and replayed male vibratory courtship signals) in eliciting a female's vibratory response was compared with that of synthetic stimuli in a plant-dwelling spider (Cupiennius salei). Specifically, the role of interseries (pauses between consecutive male series) was evaluated. Effectiveness was assessed by the number of responding females and the number of responses per female per stimulus. In case of both synthetic and natural stimuli, effectiveness increases with increasing duration of interseries in both measures. Interseries are thus represented in the female's innate releasing mechanism. However, synthetic stimuli are less effective (about 55%) than natural stimuli (set 100%). With decreasing interseries, the number of female responses per unit time sharply increases in case of playback of natural stimuli, but only slightly in case of synthetic stimuli. Since males courting on plants decrease interseries as soon as a female responds, thus facilitating their orientation, the data obtained with natural stimuli much better fit natural male courtship behaviour. This finding brings into question the validity of the synthetic stimulus. In the bioacoustics literature there is neither consensus on the effectiveness of a synthetic stimulus necessary to qualify it for behavioural analysis nor on how to measure effectiveness. We propose three measures : the percentage of responding animals, the action pattern of the response and the number of responses. It may be crucial, particularly when addressing evolutionary questions, to use either natural stimuli or synthetic stimuli (nearly) as effective as natural stimuli to avoid biased sampling of experimental animals and results difficult to interpret in biological terms.     

The influence of muscle activation on impact dynamics during lateral falls on the hip

Muscle activation has been demonstrated to influence impact dynamics during scenarios including running, automotive impacts, and head impacts. This study investigated the effects of targeted muscle activation magnitude on impact dynamics during low energy falls on the hip with human volunteers. Fifteen university-aged participants (eight females, seven males) underwent 12 lateral pelvis release trials. Half of the trials were muscle-‘relaxed’; in the remaining ‘contracted’ trials participants isometrically contracted their gluteus medius to 20–30% of maximal voluntary contraction before the drop was initiated onto a force plate. Peak force applied to the femur-pelvis complex averaged 9.3% higher in contracted compared to relaxed trials (F = 6.798, p = .022). Muscle activation effects were greater for females, resulting in (on average) an 18.5% increase in effective pelvic stiffness (F = 5.838, p = .046) and a 23.4% decrease in time-to-peak-force (F = 5.109, p = .042). In the relaxed trials, muscle activation naturally increased during the impact event, reaching levels of 12.8, 7.5, 11.1, and 19.1% MVC at the time of peak force for the gluteus medias, vastus lateralis, erector spinae, and external oblique, respectively. These findings demonstrated that contraction of trunk and hip musculature increased peak impact force across sexes. In females, increases in the magnitude and rate of loading were accompanied (and likely driven) by increases in system stiffness. Accordingly, incorporating muscle activation contributions into biomechanical models that investigate loading dynamics in the femur and/or pelvis during lateral impacts may improve estimate accuracy.     

The ability of prolactin to change the sensitivity of the pituitary of the lactating rat to luteinising hormone releasing hormonein vitro

The ability of prolactin to influence the responsiveness of the lactating rat pituitary to luteinising hormone releasing hormone has been examinedin vitro. The pituitary responsivenessin vivo to luteinising hormone releasing hormone decreased as a function of increase in the lactational stimulus. Prolactin inhibited the spontaneousin vitro release of luteinising hormone and follicle stimulating hormone to a small extent, from the pituitary of lactating rats with the suckling stimulus. However, it significantly inhibited the release of these two hormones from luteinising hormone releasing hormone-stimulated pituitaries. The responsiveness of pituitaries of rats deprived of their litter 24 h earlier, to luteinising hormone releasing hormone was also inhibited by prolactin, although minimal. It was concluded that prolactin could be influencing the functioning of the pituitary of the lactating rat by (a) partially suppressing the spontaneous release of gonadotropin and (b) inhibiting the responsiveness of the pituitary to luteinising hormone releasing hormone.     

Male-Male Clasping May Be Part of an Alternative Reproductive Tactic in Xenopus laevis

Male Xenopus laevis frogs have been observed to clasp other males in a sustained, amplectant position, the purpose of which is unknown. We examined three possible hypotheses for this counter-intuitive behavior: 1) clasping males fail to discriminate the sex of the frogs they clasp; 2) male-male clasping is an aggressive or dominant behavior; or 3) that males clasp other males to gain proximity to breeding events and possibly engage in sperm competition. Our data, gathered through a series of behavioral experiments in the laboratory, refute the first two hypotheses. We found that males did not clasp indiscriminately, but showed a sex preference, with most males preferentially clasping a female, but a proportion preferentially clasping another male. Males that clasped another male when there was no female present were less likely to “win” reproductive access in a male-male-female triad, indicating that they did not establish dominance through clasping. However, those males did gain proximity to oviposition by continued male-male clasping in the presence of the female. Thus, our findings are consistent with, but cannot confirm, the third hypothesis of male-male clasping as an alternative reproductive tactic.     

Androgens and male mating behavior in rough-skinned newts, Taricha granulosa

Cyproterone acetate was administered either orally or intraperitoneally to intact, adult male newts, Taricha granulosa. The number of males that exhibited the courtship behavior of clasping when tested with nuptial females was not altered by the antiandrogen treatments. In males which were unresponsive to nuptial females, the occurrence of clasping was not evoked by injections for 4 days of testosterone, dihydrotestosterone, or 11-ketotestosterone. Further, the incidence of clasping was not significantly elevated by injections of prolactin and/or testosterone for 30 days. The effect of sexual activity on testosterone and dihydrotestosterone levels in male newts was determined by radioimmunoassay of plasma collected from males which were: (1) isolated from females; (2) allowed to clasp a female for 2 min; or (3) allowed to clasp a female for 1 hr. The testosterone and dihydrotestosterone levels were unchanged during this period of clasping. In February and again in June, plasma androgen concentrations were measured in males which differed in their propensity to initiate courtship when paired with females. Androgen levels were similar for males that clasped a female and males that never attempted to clasp a female. Plasma androgen levels in the male newt are apparently not correlated with sexual responsiveness.     

Influence of testosterone and/or luteinizing hormone releasing hormone analogue on precocious sexual development in the juvenile rainbow trout

The influence of testosterone, luteinizing hormone releasing hormone (LHRH) agonist and combinations of these hormones on gonadotropic hormone (GtH) levels in the sexually immature trout was investigated. Both the steroid and releasing hormone preparations, testosterone in Silastic capsules and cholesterol-pelleted LHRH-A, were formulated for sustained release and long-term biological action following a single hormone implantation. Marked increases in pituitary GtH followed testosterone and/or testosterone and LHRH analogue treatment combined, but the low pituitary GtH level in controls remained unchanged after LHRH analogue administration alone. Plasma GtH titers increased with time after testosterone treatment, indicating a positive steroid feedback effect by androgen on GtH in the juvenile rainbow trout. When combined with testosterone treatment, LHRH analogue augmented plasma GtH levels compared to fish receiving testosterone treatment alone. In males the elevated plasma GtH levels were associated with testes stimulation and onset of spermatogenesis; in females, however, no significant stimulation of the ovaries was observed. It can be concluded from these studies that the testosterone stimulus is sufficient to induce onset of sexual development in immature males but not females. Whereas LHRH analogue releases GtH from the testosterone-primed trout pituitary, LHRH treatment alone under these conditions fails to stimulate the juvenile trout reproductive system.     

Prolactin modulation of the maternal-like behavior displayed by juvenile rats

Reports of elevated prolactin (Prl) levels in juvenile rats of the same strain and approximate age, together with the established role of Prl in maternal behavior in adult female rats, prompted us to examine the possible involvement of Prl in the expression of maternal-like behavior in juvenile Sprague-Dawley males and females. Experiment 1 showed that at 25 days of age both sexes exhibited a rapid onset of full maternal behavior (FMB), with males (median = 2.0 days) responding significantly more quickly than females (median = 4.0 days). Moreover, blood sampled for Prl revealed that males had significantly higher levels of circulating Prl than females, (21.0 vs 10.4 ng/ml, respectively). In Experiment 2, CB-154 treatment significantly delayed the onset of FMB in males only, causing latencies to increase to 5.0 days vs 2.0 days for Controls. Female latencies were unaffected by CB-154, 7.0 and 7.5 days for CB-154 and Control groups, respectively. A second set of both male and female juveniles was treated with either CB-154 or vehicle. CB-154 reduced Prl levels in both sexes. In the Controls, the sex difference in Prl levels (males greater than females) was again evident. In Experiment 3 juvenile males were treated with either ovine Prl (0.5 mg) + CB-154, CB-154 + Vehicle, or Vehicle + Vehicle and tested for FMB. Males treated with Prl + CB-154 required 3.0 days to exhibit FMB, significantly faster than CB-154 + Vehicle males which responded in 8.0 days. The response of Vehicle + Vehicle males was intermediate, with a latency of 5.0 days. These results provide support for the idea that Prl is involved in the maternal-like responsiveness shown by 25 day old juvenile males, but that in females a maturational factor may have prevented both heightened responsiveness to pups by 25 days of age and sensitivity to the Prl releasing mechanism(s)/Prl feedback involved in the exhibition of maternal behavior.     

Erectile function and bulbospongiosus EMG activity in estrogen-maintained castrated rats vary with behavioral context.

Electromyographic (EMG) activity in the bulbospongiosus muscles (BS) was recorded to monitor potential castration-induced alterations in muscle activity during copulation and reflexive erections. EMG recordings were made from intact male rats and from castrated rats maintained from 7 to 50 days on estradiol benzoate (300 micrograms/day) or testosterone (200 micrograms/day). Despite a 40-50% postcastration reduction in the weight of the BS and accessory sexual glands in estrogen-treated rats, the pattern of EMG activity during copulation was similar across groups. In estradiol-treated males, the EMG burst frequency during mounts and burst duration during intromissions exceeded the parameters of intact males and of castrated males maintained on testosterone. Between intromissions, and following ejaculatory patterns, estrogen-treated males displayed spontaneous muscle bursts accompanied by visually confirmed erection of the glans penis, but these males quickly lost the capacity for reflexive erections. These data demonstrate that despite castration-induced atrophy of the penile muscles and, presumably, their spinal motor nuclei, the motor output to these muscles is maintained following androgen removal. The capacity for substantial penile erection is retained during copulation long after reflexive erections have diminished.     

Rapid corticosterone-induced impairment of amplectic clasping occurs in the spinal cord of roughskin newts (taricha granulosa)

Courtship clasping, a reproductive behavior in male roughskin newts (Taricha granulosa), is rapidly blocked by an action of corticosterone (CORT) at a specific neuronal membrane receptor. The CORT-induced impairment of clasping in behaving newts appears to be mediated partly by an elimination of clasping-related activity in medullary reticulospinal neurons. Previous studies of rapid CORT actions in Taricha have focused on the brain, so existence of CORT action in the spinal cord or peripheral nervous system has not been assessed. The present study used newts with a high cervical spinal transection to examine potential spinal or peripheral CORT effects on clasping by the hindlimbs in response to pressure on the cloaca. Spinal transection causes clasps elicited by cloacal stimulation to be very sustained beyond the termination of the eliciting stimulus. In spinally transected newts, CORT caused a dose-dependent depression in the duration as well as quality of the clasp that appeared within 10 min of injection. CORT selectively impaired the usual sustained maintenance of a clasp after termination of cloacal stimulation, but not clasp elicitation during stimulation. These effects were not produced by dexamethasone, a synthetic glucocorticoid that binds poorly to the CORT membrane receptor. The CORT effect on clasp maintenance but not clasp elicitation implies selective action on an intraspinal generator for clasping but not on sensory or efferent neuromuscular aspects of the response. These results indicate the presence in the newt spinal cord of the CORT membrane receptor that exerts functional effects distinctly different from those on the brainstem.     

Multisensory signals trigger approach behaviour in the fire-bellied toad Bombina orientalis: sex differences and call specificity

Animal communication often involves multimodal signals, and interactions between sensory modalities can trigger unique responses in receivers. Response to social signals was investigated in fire-bellied toads by exposing them to playback of male calls (advertisement and release calls) and a video clip of a male conspecific in the laboratory. The cues were presented in isolation and as a combined bimodal stimulus, and approach frequency, latency to approach and time spent around the stimulus source were measured. No positive phonotaxis was observed toward the advertisement call, both during the day and during a phonotaxis trial performed at night. However, females, but not males, approached with greater frequency, lower latency, and spent more time near the source of the bimodal stimulus in an experiment involving the advertisement call. Female response was specific to the advertisement call, as approach was not increased when the release call was used. Males, on the other hand, did not show increased approach in the advertisement call experiment, but approached with greater frequency the bimodal stimulus involving the release call within the first minute of stimulus presentation. The findings suggest that females orient toward calling males and that males eavesdrop on release calls, but in both cases a visual stimulus is also needed to trigger a response. Social approach in Bombina orientalis is thus dependent on multisensory cues, and the nature of the interaction between sensory modalities depends on receiver sex and call type.     

Locomotor activity in a novel environment predicts both responding for a visual stimulus and self-administration of a low dose of methamphetamine in rats

There is evidence that visual stimuli used to signal drug delivery in self-administration procedures have primary reinforcing properties, and that drugs of abuse enhance the reinforcing properties of such stimuli. Here, we explored the relationships between locomotor activity, responding for a visual stimulus, and self-administration of methamphetamine (METH). Rats were classified as high or low responders based on activity levels in a novel locomotor chamber and were subsequently tested for responding to produce a visual stimulus followed by self-administration of a low dose of METH (0.025 mg/kg/infusion) paired with the visual stimulus. High responder rats responded more for the visual stimulus than low responder rats indicating that the visual stimulus was reinforcing and that operant responding for a visual stimulus has commonalities with locomotor activity in a novel environment. Similarly, high responder rats responded more for METH paired with a visual stimulus than low responder rats. Because of the reinforcing properties of the visual stimulus, it was not possible to determine if the rats were responding to produce the visual stimulus, METH or the combination. We speculate that responding to produce sensory reinforcers may be a measure of sensation seeking. These results indicate that visual stimuli have unconditioned reinforcing effects which may have a significant role in acquisition of drug self-administration, a role that is not yet well understood.     

Length-dependent electromechanical coupling in single muscle fibers

In single muscle fibers from the giant barnacle, a small decrease in muscle length decreases both the calcium activation and the peak isometric tension produced by a constant current stimulus. The effect is most pronounced if the length change immediately precedes the stimulation. In some cases, the decrease in tension with shortening can be accounted for almost entirely by a decrease in calcium release rather than changes in mechanical factors such as filament geometry. During the constant current stimulation the muscle membrane becomes more depolarized at longer muscle lengths than at the shorter muscle lengths. Under voltage clamp conditions, when the membrane potential is kept constant during stimulation, there is little length dependence of calcium release. Thus, the effect of length on calcium release is mediated through a change in membrane properties, rather than an effect on a subsequent step in excitation-contraction coupling. Stretch causes the unstimulated fiber membrane to depolarize by about l mV while release causes the fiber membrane to hyperpolarize by about the same amount. The process causing this change in potential has an equilibrium potential nearly 10 mV hyperpolarized from the resting level. This change in resting membrane potential with length may account for the length dependence of calcium release.     

Sex steroids and vasotocin interact in a female amphibian (Taricha granulosa) to elicit female-like egg-laying behavior or male-like courtship.

Female egg-laying behaviors and male amplectic clasping behaviors in the rough-skinned newt (Taricha granulosa) are similar in that animals clasp an object. In the case of egg-laying, females clasp submerged inanimate objects, whereas in amplexus, males clasp conspecific females. Considering these behavioral similarities and differences, we investigated the possibility that gonadal steroids and vasotocin (AVT) interact to control egg-laying behaviors, as has been shown for the control of amplexus in Taricha males. Intact, gravid T. granulosa females injected ip with AVT, unlike those injected with saline, exhibited egg-laying behaviors and oviposition. In ovariectomy-steroid-implant studies, no saline-injected female exhibited egg-laying behaviors, whereas AVT-injected ovariectomized females exhibited egg-laying behaviors if implanted with estradiol (E2), testosterone, or dihydrotestosterone (DHT), and not if implanted with empty capsules. When given a choice between clasping aquatic vegetation or other females (amplectic clasping), following an AVT injection, unoperated and sham-operated control females and ovariectomized females with E2 implants did not preferentially clasp aquatic vegetation over other females. In contrast, AVT-injected ovariectomized females with DHT implants preferentially clasped other females. Thus, exposure of Taricha females to estrogens or androgens appears to determine whether the AVT-induced clasping is egg-laying or amplectic clasping.     

Sexual differentiation and hormonal regulation of the laryngeal synapse in Xenopus laevis

In Xenopus laevis frogs, sex differences in adult laryngeal synapses contribute to sex differences in vocal behavior. This study explores the development of sex differences in types of neuromuscular synapses and the development and hormone regulation of sex differences in transmitter release. Synapses in the juvenile larynx have characteristics not found in adults: juvenile muscle fibers can produce subthreshold or suprathreshold potentials in response to the same strength of nerve stimulation and can also produce multiple spikes to a single nerve stimulus. Juvenile laryngeal muscle also contains the same synapse types (I, II, and III) as are found in adult laryngeal muscle. The distribution of laryngeal synapse types in juveniles is less sexually dimorphic than the distribution in adults. Analysis of quantal content indicates that laryngeal synapses characteristically release low amounts of transmitter prior to sexual differentiation. Quantal content values from male and female juveniles are similar to values for adult males and are lower than values for adult females. When juveniles are gonadectomized and treated with exogenous estrogen, quantal content values increase significantly, suggesting that this hormone may increase transmitter release at laryngeal synapses during development. Gonadectomy alone does not affect quantal content of laryngeal synapses in either sex. Androgen treatment decreases quantal content in juvenile females but not males; the effect is opposite to and smaller than that of estrogen. Thus, muscle fiber responses to nerve stimulation and transmitter release are not sexually dimorphic in juvenile larynges. Transmitter release is strengthened, or feminized, by the administration of estradiol, an ovarian steroid hormone. © 1995 John Wiley & Sons, Inc.     

Restoration of abdominal wall integrity as a salvage procedure in difficult recurrent abdominal wall hernias using a method of wide myofascial release

The management of primary and recurrent giant incisional hernias remains a complex and frustrating challenge even with multiple alloplastic and autogenous closure options. The purpose of this study was to develop a reconstructive technique of restoring abdominal wall integrity to a subcategory of patients, who have failed initial hernia therapy, by performing superior and lateral myofascial release. Over a 1.5-year period, 10 patients with previously unsuccessful treatment of abdominal wall hernias, using either primary repair or placement of synthetic material, were studied. The patients had either recurrence of the hernia or complications such as infections requiring removal of synthetic material. The hernias were not able to be treated with standard primary closure techniques or synthetic material. The average defect size was 19 x 9 cm. Each patient underwent wide lysis of bowel adhesions releasing the posterior abdominal wall fascia to the posterior axillary line, subcutaneous release of the anterior abdominal wall fascia to a similar level, and complete removal of any synthetic material (if present). The abdominal domain was reestablished by releasing the laterally retracted abdominal wall. The amount of available abdominal wall tissue was increased by wide release of the cephalic abdominal wall fascia overlying the costal margin and the external oblique fascia and muscle laterally. If needed, partial thickness of the internal oblique muscle and its anterior fascia were also released laterally to perform a tension-free primary closure of the defect. All repairs were closed with satisfactory functional and aesthetic results. All alloplastic material was removed. Fascial release was limited so as to close only the hernia defect without tension. No significant release of the rectus sheath and muscle was needed. Good, dynamic muscle function was noted postoperatively. All repairs have remained intact, and no further abdominal wall hernias have been noted on follow-up.     

Sexually stimulated testosterone release in male mice (Mus musculus): roles of genotype and sexual arousal

In virtually every mammalian species examined, some males exhibit reflexive testosterone release upon encountering a novel female (or female-related stimulus). At the same time, not every individual male (or every published study) provides evidence for reflexive testosterone release. Four experiments using house mice (Mus musculus) examined the hypothesis that both the male's genotype and his degree of sexual arousal (as indexed by ultrasonic mating calls) are related to such variability. In Experiment 1, CF-1 males exhibited reflexive testosterone elevations 30 min after encountering female urine. CK males, on the other hand, did not exhibit testosterone elevations 20, 30, 50, 60, or 80 min after encountering female urine (Experiments 1 and 2) suggesting this strain incapable of reflexive release. In Experiment 3, we measured both mating calls and reflexive testosterone release in response to female urine in CF-1 and CK males. Most males of both strains called vigorously to female urine but not to water. But, only CF-1 males exhibited significant testosterone elevations to female urine. In Experiment 4, DBA/2J males called vigorously to females followed by testosterone elevations 30 min later. The first 3 experiments support the hypothesis that male genotype is an important variable underlying mammalian reflexive testosterone release. Statistically significant correlations between mating calls in the first minute after stimulus exposure and testosterone elevations 30 min later (Experiments 3 and 4) support the hypothesis that, in capable males, reflexive testosterone release is related to the male's initial sexual arousal.     

Sex recognition by male Andrew's toad Bufo andrewsi in a subtropical montane region

Sex recognition is important for successful reproduction and species usually have efficient systems of signals and responses to find the optimal potential mate. In the present study, we investigated the ability of males to recognize between sexes for two stimulus animals in Andrew's toad Bufo andrewsi, a species widely distributed in western China. When a male was placed with a gravid female and a similar-sized male, the male did not discriminate between them. When two males with distinct size differences were provided with a male, the male chose the larger one. In an experiment in which a gravid female and a different-sized male were offered a test male, males preferred the larger gravid females than smaller males. If a test male clasped a stimulus male, the stimulus male uttered a specific release call that caused the test male to release the stimulus male. These findings suggest that male B. andrewsi can recognize between the sexes probably based on male release calls, and prefer to mate with larger individuals with visual cues.     

EMG study on the effect of ageing on the human masseteric jaw-jerk reflex

The effect of age on the masseteric jaw-jerk reflex was investigated in 22 young (11 males and 11 females with mean age 23.2 years) and 22 older dentate subjects (11 males and 11 females with mean age 61.3 years). Electromyographic (EMG) recordings were obtained, after chin taps, from the relaxed masseter muscle of the preferred chewing side, by use of a computerised recording and analysis system. With increasing age the occurrence of the reflex was reduced, the latency was increased, while the amplitude was decreased. Those findings are probably related to the general age related changes in the muscular tissue, the sense organs, the peripheral nerves and especially the central nervous system, Increased biological variance was also observed in the older subjects, as in most aspects of performance in the latent years. Furthermore, the effects of ageing were generally similar in men and women. The age-related decrement in the monosynaptic reflex response is indicative of a generalised decline in the motor performance of the stomatognathic system and the decreased ability of the older dental patient to easily adapt to any dramatic changes in the sensory input.     

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.