Effect of sex on torque, recovery, EMG, and MMG responses to fatigue.

OBJECTIVE: The purpose of the present investigation was to examine the effect of sex on maximal voluntary isometric contraction (MVIC) torque and the EMG and MMG responses as a result of fatiguing, intermittent, submaximal (65% of MVIC), isometric elbow flexion muscle contractions. METHODS: Eighteen men and women performed MVIC trials before (pretest), after (posttest), and 5-min after (5-min recovery) performing 50 intermittent, submaximal isometric muscle contractions. Surface electromyographic (EMG) and mechanomyographic (MMG) signals were simultaneously recorded from the biceps brachii muscle. RESULTS: As a result of the fatiguing workbout torque decreased similarly from pretest to posttest for both the men (24.0%) and women (23.3%). After 5-min of recovery, torque had partially recovered for the men, while torque had returned to pretest levels for the women. For both sexes, from pretest to posttest EMG mean power frequency and MMG amplitude decreased, but returned to pretest levels after 5-min of recovery. CONCLUSIONS: In the present study, there were sex-related differences in muscle fatigue that were not associated with the EMG or MMG responses.

Effects of fatiguing constant versus alternating intensity intermittent isometric muscle actions on maximal torque and neuromuscular responses.

OBJECTIVE: To determine the effects of constant versus alternating applications of torque during fatiguing, intermittent isometric muscle actions of the leg extensors on maximal voluntary isometric contraction (MVIC) torque and neuromuscular responses. METHODS: Sixteen subjects performed two protocols, each consisting of 50 intermittent isometric muscle actions of the leg extensors with equal average load at a constant 60% MVIC or alternating 40 then 80% (40/80%) MVIC with a work-to-rest ratio of 6-s on and 2-s off. MVIC torque as well as electromyographic signals from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) and mechanomyographic signals from the VL were recorded pretest, immediately posttest, and 5-min posttest. RESULTS: The results indicated that there were no time-related differences between the 60% MVIC and 40/80% MVIC protocols. The MVIC torque decreased posttest (22 to 26%) and remained depressed 5-min posttest (9%). There were decreases in electromyographic frequency (14 to 19%) and mechanomyographic frequency (23 to 24%) posttest that returned to pretest levels 5-min posttest. There were no changes in electromyographic amplitude and mechanomyogrpahic amplitude. CONCLUSIONS: These findings suggested that these neuromuscular parameters did not track the fatigue-induced changes in MVIC torque after 5-min of recovery.

Four weeks of high- versus low-load resistance training to failure on the rate of torque development, electromechanical delay, and contractile twitch properties.

The purpose of this study was to investigate the effects of 4-weeks of high- versus low-load resistance training to failure on rate of torque development (RTD), electromechanical delay (EMD), and contractile twitch characteristics. Fifteen men (mean±SD; age=21.7±2.4 yrs) were randomly assigned to either a high- (80% 1RM; n=7) or low-load (30% 1RM; n=8) training group and completed elbow flexion resistance training to failure 3 times per week for 4 weeks. The participants were tested at baseline, 2-, and 4-weeks of training. Peak RTD (pRTDV) and RTD at 0-30 (RTD30V), 0-50 (RTD50V), 0-100 (RTD100V), and 0-200 (RTD200V) ms, integrated EMG amplitude (iEMG) at 0-30, 0-50, and 0-100 ms, and EMD were quantified during maximal voluntary isometric muscle actions. Peak twitch torque, peak RTD, time to peak twitch, 1/2 relaxation time and the peak relaxation rate were quantified during evoked twitches. Four weeks of high-load, but not low-load resistance training, increased RTD200V. There were also increases in iEMG during the first 30 ms of muscle activation for the high- and low-load groups, which may have indirectly indicated increases in early phase motor unit recruitment and/or firing frequency. There were no significant training-induced adaptations in EMD or contractile twitch properties.

Electromyographic Responses from the Vastus Medialis during Isometric Muscle Actions.

This study examined the electromyographic (EMG) responses from the vastus medialis (VM) for electrodes placed over and away from the innervation zone (IZ) during a maximal voluntary isometric contraction (MVIC) and sustained, submaximal isometric muscle action. A linear electrode array was placed on the VM to identify the IZ and muscle fiber pennation angle during an MVIC and sustained isometric muscle action at 50% MVIC. EMG amplitude and frequency parameters were determined from 7 bipolar channels of the electrode array, including over the IZ, as well as 10 mm, 20 mm and 30 mm proximal and distal to the IZ. There were no differences between the channels for the patterns of responses for EMG amplitude or mean power frequency during the sustained, submaximal isometric muscle action; however, there were differences between channels during the MVIC. The results of the present study supported the need to standardize the placement of electrodes on the VM for the assessment of EMG amplitude and mean power frequency. Based on the current findings, it is recommended that electrode placements be distal to the IZ and aligned with the muscle fiber pennation angle during MVICs, as well as sustained, submaximal isometric muscle actions.

Müllerian duct anomalies: MR imaging evaluation.

Twenty-nine patients underwent magnetic resonance (MR) imaging for investigation of müllerian duct anomalies (MDAs). The anomalies evaluated were uterine agenesis (n = 2), uterine hypoplasia (n = 5), unicornuate uterus (n = 5), uterus didelphys (n = 5), bicornuate uterus (n = 10), and septate uterus (n = 2). The MR imaging interpretation was correlated with results of laparotomy (n = 18), hysterosalpingography (HSG) (n = 5), laparoscopy (n = 2), hysteroscopy (n = 1), HSG and laparotomy (n = 2), and HSG and laparoscopy (n = 1). MR imaging enabled correct classification of the anomaly in each patient and identification of coincidental gynecologic disease in 10 patients (34%). MR imaging results influenced clinical treatment in six (24%) of 25 patients referred prospectively. Of particular value was the ability to characterize septal tissue (myometrium versus fibrous tissue), identify the patients in whom the septum of bicornuate uteri had both fibrous and myometrial components, and establish that suspected adnexal lesions were actually components of obstructed MDAs.

Vaginal reconstruction after exenteration with use of gracilis myocutaneous flaps: the University of California, San Francisco experience.

At the University of California, San Francisco Medical Center we have performed 18 vaginal reconstructive procedures with gracilis flaps at the time of anterior, posterior, or total pelvic exenteration. We have compared these patients with 13 other patients undergoing exenteration during the same interval who chose not to have vaginal reconstruction. There was no significant difference between the two groups with respect to age, weight, operating time, blood loss, or duration of postoperative hospitalization, but there were significantly fewer serious complications in the patients receiving gracilis flaps. The results of a questionnaire indicated that the perineal cosmetic results are highly acceptable, although residual scarring on the legs is a common source of minor complaint. Sexual adjustment can be complete or nearly complete in surviving patients. Given the major contribution to wound healing, reduced postoperative morbidity, excellent cosmetic results, and the opportunity for complete sexual rehabilitation, we believe the gracilis myocutaneous flap neovagina remains the procedure of choice for most women undergoing major exenterative procedures.

Vaginal adenosis in women born prior to the diethylstilbestrol era.

Vaginal adenosis was evaluated in 41 women, all of whom had been born prior to the diethylstilbestrol (DES) era, and compared with the adenosis commonly encountered in DES-exposed progeny. The patients were 24 to 88 years of age (median, 44 years). Six of the women were symptomatic, and in four of these six the glands were enmeshed in a marked inflammatory infiltrate. In an additional 26 women the adenosis was discovered as incidental, nonsymptomatic macroscopic nodules or cysts. The remaining nine cases of adenosis were discovered by pathologists. Three types of epithelia characterized the glands: mucinous, tuboendometrial, and embryonic. Mucinous columnar cells resembling the lining of the normal endocervix and tuboendometrial cells resembling the lining of the normal fallopian tube or endometrium constituted the glands exclusively in 22 and eight specimens, respectively, and as a mixture in seven. The glands lined by mucinous cells most often presented clinically as cysts or nodules. The specimens composed of tuboendometrial cells were most often discovered on microscopic examination. The third type of epithelium, composed of embryonic columnar cells, was encountered in four specimens. These glands, less than 30 micron in greatest diameter, were located at the junction between the lamina propria and the squamous epithelium, and were incidental microscopic findings. It is concluded that the microscopic appearances of adenosis in women born prior to the DES era are identical to those encountered in young women exposed in utero to DES.

Legionella pneumophila in coal miners.

Legionnaires' disease was diagnosed in three mineworkers at a colliery. Investigation of water samples from various sites at the colliery did not discover a source of the infection. Results of serological surveys undertaken on the workmates of the patients and other miners showed only one additional positive Legionella indirect fluorescent antibody test. There was, therefore, no justification for any alteration in the water supply or the ventilation at the colliery.

Chlamydia trachomatis and cervical neoplasia.

We tested 383 women with and 500 women without cervical neoplasia for antibodies against Chlamydia trachomatis or herpes simplex virus (HSV). Exposure to both agents was related to sexual activity, with the highest prevalence of antibodies found in women with more sex partners and who had first coitus at an earlier age. When subjects were matched for several risk factors (age, race, marital status, parity, number of sex partners, and history of venereal disease), a significant excess of antibodies against C trachomatis was found in cases as compared with control subjects (76.5% v 58.4%, respectively; n = 149). Because matched-pair analysis lost a substantial proportion of women with neoplasia (largely because they were older), linear logistic analysis was performed. This also showed an excess of antichlamydial antibody in cases, with an estimated odds ratio of approximately 2 for the association of antichlamydial antibody and the risk of being a case. Neither analysis found an excess of antibodies to HSV type 2 in cases.

Radical surgery in the management of clear cell adenocarcinoma of the cervix and vagina in young women.

The treatment of clear cell adenocarcinoma of the cervix and vagina in young women has varied widely from one institution to another. Since 1956, 16 such patients have been treated primarily with radical surgery at the University of California, San Francisco. The operations have ranged from radical hysterectomy and bilateral pelvic lymph node dissection with preservation of the ovaries to total pelvic exenteration, depending upon the location and extent of the disease. Vaginal reconstruction has been carried out in most of the patients who required vaginectomy. Eleven of the 16 patients are living and well. The remaining five have died of disease, two of them after relatively long disease-free intervals.

Radical surgery for the treatment of early invasive cervical carcinoma (stage IB): review of 15 years' experience.

From 1963 through 1977, 108 patients with stage IB cervical carcinoma were treated with radical hysterectomy and pelvic lymphadenectomy at the University of California, San Francisco. Forty-four of 48 patients followed for 5 or more years after surgery are known to be alive (5-year survival rate, 91.7%). The 5-year survival rate of all 108 patients using the life-table method is 93.4%. Complications in this series were few; only 1 patient developed a ureterovaginal fistula.

Chlamydial infection in women with cervical dysplasia.

The prevalence of antibodies to chlamydiae, particularly to TRIC (trachoma-inclusion conjunctivitis) agents, was studied in women with cervical dysplasia and in women attending selected clinics (obstetrics, cancer-screening, and gynecology). In addition, attempts were made to isolate TRIC agents and herpesviruses from the cervices of these women. TRIC agent recovery rates 4.1 per cent for women with dysplasia, 5.4 per cent for pregnant women, 7.8 per cent in the women's clinic, and 0.8 per cent in the cancer-screening clinic. Herpesvirus recovery rates were lower, on the order of 1 per cent or less in each clinic. Complement-fixing antibodies to chlamydial group antigen were detected in 21.5 per cent of women with dysplasia. With a more sensitive fluorescent antibody method, 77.6 per cent of the women with dysplasia or cervical cancer were shown to have antibodies to chlamydiae. In general, antichlamydial antibodies were less prevalent in the other clinic populations. The results of this study indicate that women with cervical dysplasia or cancer may have a high prevalence of antibodies to sexually transmitted agents other than herpesvirus type 2.

Are chlamydial infections the most prevalent venereal disease?

We studied two population groups (more than 1,600 patients) to determine the prevalence and clinical associations of genital tract infections with chlamydiae and herpesviruses. Base-line isolation rates for asymptomatic women having routine pelvic examinations were much lower than rates for symptomatic women. In both groups, chlamydiae were more prevalent than herpesviruses. Chlamydial infection was associated much more commonly with cervicitis (36.6%) than with vaginitis only (4.1%). Among 282 symptomatic men, the cultures of 19.9% yielded chlamydiae, and 4.3%, herpesviruses. Chlamydiae were recovered from 35.5% (27 of 76) of specimens from men with nongonococcal urethritis, and from an even larger proportion, 57% (24 of 42), of the specimens from men with frank discharge.