Beverly A. Bullen

Induction of Menstrual Disorders by Strenuous Exercise in Untrained Women

We performed a prospective study of 28 initially untrained college women with documented ovulation and luteal adequacy to determine whether strenuous exercise spanning two menstrual cycles would induce menstrual disorders. To ascertain the influence, if any, that weight loss might exert, we randomly assigned the subjects to weight-loss and weight-maintenance groups. Subjects were expected to run 4 miles (6.4 km) per day, progressing to 10 miles (16.1 km) per day by the fifth week, and to engage daily in 31/2 hours of moderate-intensity sports. The normalcy of the menstrual cycles during the period of exercise was judged independently according to clinical and hormonal criteria, the latter comprising serial measurements of gonadotropin and sex-steroid excretion. A higher percentage of abnormalities proved to be detectable by hormonal means (P less than 0.02). Only four subjects (three in the weight-maintenance group) had a normal menstrual cycle during training. In the weight-loss group, the number of women who had luteal abnormalities as compared with those who lost the surge in luteinizing hormone altered significantly over time, the latter occurring more frequently (P less than 0.01) as training progressed. Within six months of termination of the study, all subjects were again experiencing normal menstrual cycles. We conclude that vigorous exercise, particularly if compounded by weight loss, can reversibly disturb reproductive function in women.

Physical Conditioning Facilitates the Exercise-Induced Secretion of Beta-Endorphin and Beta-Lipotropin in Women

EXERCISE training is used increasingly to prevent and treat disease, and millions of healthy persons participate in strenuous sports; yet, the mechanisms by which exercise produces various clinical...

Hypothalmic Amenorrhea in Runners of Normal Body Composition

Three amenorrheic runners of normal body weight, in whom organic disease had been excluded, were found to exhibit: (1) normal body composition, (2) low baseline concentrations of serum LH and normal concentrations of FSH, (3) normal to hyper-responsiveness of LH and FSH to GnRH testing, and (4) normal and possibly increased frequency of LH pulsations. In one of the 3 runners, the administration of naloxone was followed by a pronounced increase in the amplitude of the LH pulsations.

Strenuous exercise with caloric restriction: effect on luteinizing hormone secretion.

To test whether strenuous exercise with and without caloric restriction alters LH secretion, and whether these changes are apparent in the immediate post-exercise period, LH pulse parameters were studied in four moderately trained eumenorrheic women over three successive menstrual cycles. Blood samples were obtained 5 h before and 5 h after 90 min of running at 74% VO2max. Each test was preceded by a 7-d treatment of controlled diet and exercise (74% VO2max). During CONTROL, subjects were eucaloric on days 1-7, and performed no exercise on days 5-7. During STTI (short-term training increase), subjects were eucaloric and completed 90 min runs on days 5-7. During DIET/STTI, subjects consumed 60% of the calories necessary to maintain weight on days 1-7, and exercised as in STTI. A significant decrease in overall (0700-1830 h) LH pulse frequency during DIET/STTI compared with CONTROL and STTI treatments was observed. No changes were found in mean serum LH levels or peak amplitude. These results suggest that high-volume training combined with caloric restriction may predispose one to exercise-induced changes in LH pulse frequency, while adequate caloric intake may prevent these changes.

Effects of short-term strenuous endurance exercise upon corpus luteum function.

PURPOSE The present study tested whether short-term, abruptly initiated training can cause corpus luteum dysfunction when exercise is limited to either the follicular or luteal phase of the cycle. METHODS Reproductive hormone excretion and menstrual characteristics were studied in sedentary women who exercised only during the follicular (N = 5) or the luteal (N = 4) phase. Six women served as controls, three of whom exercised at a low volume and three who remained sedentary. Weekly progressive increments in exercise volume continued until either ovulation (follicular group) or menses (luteal group) occurred. Physical activity and nutrient intake were closely monitored with the intent to maintain body weight. RESULTS No luteal phase disturbances occurred in any of the control subjects, whereas 40% of follicular and 50% of luteal exercisers experienced luteal defects. The proportion of menstrual cycles disrupted was not different between luteal and follicular exercisers (50% vs 30%, respectively) but was significantly greater than the proportion of cycles disrupted in control subjects (P < 0.05). CONCLUSIONS These results suggest that exposure to abrupt onset of training can alter luteal function, regardless of the menstrual cycle phase in which exercise occurs. This study also demonstrates that a relatively low volume of exercise suffices to induce mild disturbances in luteal function.

Melatonin Response to Exercise Training in Women

Previous human stuthes have indicated that daytime melatonin levels increase when the organism is subjected to the stress of fasting and exercise. Melatonin, epinephrine, and norepinephrine levels were measured during a mock run and in the course of treadmill exercise performed before (T‐l), during (T‐2), and following (T‐3) a progressive conditioning (running) program. Hormonal responses to the training program were determined by comparing values at T‐l and T‐3. Plasma melatonin, epinephrine, and norepinephrine levels rose significantly (P < .01) from baseline values for each exercise intensity during all three treadmill runs. While a dose‐response trend was observed in each of the norepinephrine and epinephrine trials, there appeared to be a progressive diminution of this relationship in melatonin between intensities. Further, as training progressed, the peak melatonin concentration was decreased by 52% from T‐l to T‐3, while peak epinephrine and norepinephrine values diminished only 19% and 8%, respectively. These results suggest that vigorous exercise training may attenuate rather than augment the secretion of pineal melatonin. Development of a human model of pineal responsiveness to exercise may contribute to the elucidation of exercise‐associated reproductive disorders.

Effects of follicular phase exercise on luteinizing hormone pulse characteristics in sedentary eumenorrhoeic women

OBJECTIVE Current studies reveal little regarding the Inception of exercise‐induced LH changes during physical training. This study aimed to assess the susceptibility of the hypothalamic–pituitary axis to the acute physical stress of exercise in untrained, physically inactive women. The acute effects of submaximal endurance exercise upon the pulsatile LH secretion in the follicular phase were compared with those accompanying leisurely strolling for a similar time period.

Physical Performance, Skinfold Measurements, Activity Expenditures, and Food Consumption of College Women

Abstract Members of an incoming college class enrolled in a physical education and physical therapy program were used to determine physical fitness and caloric intake and output. These data, related to results found at the end of an increasingly active year, showed that better physical performance was exhibited and that caloric intakes paralleled the increase in exercise, while weight was maintained. Of the subcutaneous fat measures made at several sites, weight loss was most reflected in loss of scapular and abdomen skinfold thickness; the opposite did not hold true for weight gain.

Athletics and nutrition

W HAT constitutes the “optimum” diet for athIetes training for competitive contests is a perennia1 question. For centuries trainers and coaches have advocated special dietary schemes, stemming from older traditions and superstitions, and based on the beIief that the ingestion of particuIar foods would augment the physical capacity or efficiency of the performer. One of the most widespread of such practices has been the advocacy of ingesting large quantities of meat meant to repIenish “muscular substance” following the “losses” supposedly incurred during severe muscuIar work. This particular practice was first recorded in Greece during the fifth century B.C., and ascribed to two athletes who had deviated from the hitherto traditional (chieAy vegetarian) diet of the time to a regimen entaiIing the intake of large quantities of meat which lead to increased body bulk and weight. The fifth century also saw a change in the cuttural outlook on physical fitness: instead of being considered essentiallya broad prerequisite for participation in the defense of the country, physical litness became subordinate to training for specilic sports, excellence in which became superior to aImost all other vaIues [21]. An attitude of this sort has not disappeared among the athIetes specializing in particular sports. In sports, such as boxing and wrestling, present day athletes, professiona and amateur (and, among the latter, even high school students), not infrequently pIace themseIves on such stringent regimens as “crash diets” combined with dehydration so as to Iose weight. This regimen causes rapid weight loss and the athIete can thus make Iower weight classifications. While it may be desirable for an overweight person to Iose weight, a crash diet is not the method to be recommended. More often the intention of those athletes is not t,o attain their most “desirabIe” weight for competition, but rather to compete with advantage against those who reaIIy do belong in a lower weight bracket. When such weight classifications have been set up to provide competition on an equitable basis, the violation of these standards by sudden self-inflicted starvation and I)>temporarydehydration serves no more the ethics of sportsmanship than it does the health of the people concerned. Such practices have recentIy been condemned by the A. AI. A. [r2i].

Effect of acute exercise on plasma neurotensin levels

Neurotensin (NT) levels were examined in five aerobically untrained females aged 20-36 engaged in acute graded exercise testing. In addition to radioimmunoassay measurements, high pressure liquid chromatography was performed to further characterize plasma NT-like immunoreactivity (NTLI). Epinephrine (E), norepinephrine (NE), and lactate (L) responses were also determined. Exercise testing consisted of one hour of treadmill running subdivided into three 20-minute segments representing 50, 60, and 70%, respectively, of the previously determined maximal aerobic capacity. Mock testing established baseline values for each subject. Three components of NTLI were evaluated: NT(1-13), NT(1-8), and NT(1-11). Resting NT(1-13) concentrations averaged 5.8 +/- 4.2 fmol/ml, while mean NT(1-8) values were 13.0 +/- 5.2 fmol/ml, and NT(1-11) averaged 5.8 +/- 3.2 fmol/ml. Peak exercise values were: for NT(1-13), 5.4 +/- 2.0 fmol/ml, for NT(1-8), 13.5 +/- 2.8 fmol/ml, and for NT(1-11), 5.9 +/- 0.5 fmol/ml. Analysis of variance with repeated measures detected no changes in these levels with exercise. Four-fold increases in E (36 +/- 3 pg/ml to 121 +/- 51 pg/ml), NE (340 +/- 95 pg/ml to 1431 +/- 319 pg/ml), and L (0.8 +/- 0.1 mM to 4.3 +/- 1.7 mM) confirmed the stress of exercise on the body in general, and the sympatho-adrenal system in particular. While other research has associated peripheral NT metabolite elevations with stressful stimuli in laboratory animals, the results of the present study suggest either that NT is not released from the human adrenal medulla during exercise, or that peripheral sampling precludes detection of any increases in NT from the adrenal medulla with currently available radioimmunoassay systems.