Women Runners Research Articles

Dietary intakes and biochemical markers of selected minerals: comparison of highly trained runners and untrained women.

Mineral status of highly trained (HT) women runners (n = 14) and untrained (UT) women (n = 11), as determined from 3-day dietary records, blood, and urine samples, was compared. HT women had significantly higher energy (HT: 2331 +/- 121 vs UT: 1973 +/- 107 kcal/day; p less than 0.05), magnesium (Mg) (HT: 369 +/- 29 vs UT: 262 +/- 18 mg/day, p less than 0.05), and potassium (K) (HT: 3874 +/- 384 vs UT: 2646 +/- 244 mg/day; p less than 0.05) intakes than UT women. However, mean daily intakes of calcium (Ca), iron (Fe), copper (Cu), and sodium (Na) were not different for the two groups. Plasma concentrations and urinary excretion of Ca, Mg, and Cu of HT and UT women did not differ. Plasma Fe concentrations of the two groups were also similar (HT: 21 +/- 2 vs UT: 22 +/- 1 mumol/L), and, although serum ferritin concentrations of HT women were lower than UT women (HT: 18 +/- 4 vs UT: 30 +/- 6 micrograms/L), the difference was not significant. Urinary Na excretion of the two groups did not differ. HT women had a higher K intake than UT women but urinary K excretion of the two groups did not differ. Whether present mineral intakes by HT women are adequate during periods of intensive training remains to be determined.

Effect of long-distance running on bone mass in women

The effect of long-distance running on bone mass was assessed in 10 premenopausal and 9 estrogen-deprived postmenopausal women and compared to that in closely matched sedentary control women. Vertebral trabecular bone density (VBD) was determined by computed tomography and radial cortical bone density (CBD) by single-photon absorptiometry. Physical fitness was assessed by determining maximal oxygen consumption (VO2max) on a treadmill run to exhaustion. VBD was 183 +/- 7 mg/cm3 and VO2max was 48 +/- 1 ml/kg per minute in young women runners and 163 +/- 8 mg/cm3 and 32 +/- 2 ml/kg per minute in sedentary young women. A positive correlation was noted between VBD and VO2max in these groups (r = 0.509, p less than 0.03). Despite a significantly higher VO2max in postmenopausal women runners compared with sedentary controls (37 +/- 2 versus 24 +/- 2 ml/kg per minute), VBD was identical (112 +/- 5 versus 111 +/- 5 mg/cm3) and no correlation was seen between VBD and VO2max (r = 0.187, p = 0.457). Radial cortical bone density was not different between the runners or sedentary groups in young women (0.738 +/- 0.01 versus 0.732 +/- 0.1 g/cm2) or postmenopausal women (0.617 +/- 0.3 versus 0.665 +/- 0.4 g/cm2). These results suggest that although physical fitness enhances vertebral bone density in premenopausal women, it does not appear to prevent age- and/or sex steroid deficiency-induced bone loss in postmenopausal women.

Zinc status of highly trained women runners and untrained women

Endurance training effects on zinc status were assessed by comparing 13 highly trained (HT) and 10 untrained (UT) women. Blood and 24-h urine samples before and after a 25-mg oral Zn load, and 3-d dietary records were evaluated. Mean daily Zn intakes did not differ and were below the Recommended Dietary Allowances for both groups. Fasting concentrations of plasma Zn, serum albumin, alpha 2-macroglobulin, and erythrocyte Zn content did not differ. However, HT women had significantly (p less than 0.05) higher urinary Zn excretion (HT: 6.7 +/- 0.8 and UT: 4.5 +/- 0.7 mumol/d) and reduced responses to the oral Zn than did UT in terms of maximal responses (HT: 11.0 +/- 1.6 and UT: 16.2 +/- 1.2 mumol/L) and areas under the curve (HT: 34.8 +/- 2.7 and UT: 43.6 +/- 2.7 mumol.L-1.4h-1). The greater urinary Zn excretion by HT women may reflect higher rates of skeletal muscle turnover. Whether their reduced responses to the Zn load reflect differences in plasma volume, entry or removal of plasma Zn, or absorption is unknown.

Effect of Exercise and Menstrual Cycle Status on Plasma Lipids, Low Density Lipoprotein Particle Size, and Apolipoproteins*

Habitual physical exercise has been reported to have beneficial effects on plasma lipoproteins. To examine this question in women, plasma cholesterol, triglyceride, and apolipoprotein (apo) A-I and B levels, and low density lipoprotein (LDL) particle size were determined in 25 women runners (9 of whom had exercise-related secondary amenorrhea) and 36 age-matched nonexercising women (controls). The eumenorrheic runners had significantly lower apo B levels and significantly greater mean apo A-I/apo B ratios and LDL particle sizes than did the control women (P less than 0.05). Lower apo B levels were correlated with decreased body mass index, a known exercise effect (P less than 0.0001). In addition, normally menstruating runners had cholesterol and triglyceride levels that were 7.6% and 25.4% lower, respectively, and apo A-I levels that were 6.4% higher than control women (P = NS). In amenorrheic runners all parameters were similar to values in control women, except that apo B levels were 20% lower (P less than 0.05). Amenorrheic runners had lower plasma apo A-I levels (13%) and significantly lower apo A-I/apo B ratios and estradiol levels than eumenorrheic runners, and serum estradiol values in the runners were correlated with apo A-I levels (P less than 0.01). These data indicate that the beneficial effects of strenuous exercise on plasma apo A-I levels and apo A-I/apo B ratios in women runners can be reversed by exercise-induced amenorrhea and decreased serum estradiol levels, and that women runners have lower apo B levels than nonexercising women, regardless of menstrual status.

Acute effects of exercise on plasma catecholamines in sedentary and athletic women with normal and abnormal menses

Norepinephrine plays a role in the regulation of luteinizing hormone secretion and may therefore be involved in the etiology of exercise-induced menstrual dysfunction. This study evaluated both intraexercise and postexercise responses of epinephrine, norepinephrine, and dopamine in sedentary women and women runners with normal and abnormal menstruation. Five eumenorrheic nonrunners and five eumenorrheic, four oligomenorrheic, and five amenorrheic runners were evaluated on 2 consecutive days. On day 1, the women cycled on a bicycle ergometer against an increasing work load until exhaustion, and on day 2, the women underwent a submaximal exercise regimen. Serial blood draws were taken at specified time intervals during intraexercise and postexercise periods on both days. The data collected during exercise for all groups showed that epinephrine and norepinephrine had a sixfold to sevenfold rise on day 1 and had a threefold rise on day 2. Dopamine increased twofold during both exercise protocols. On day 1 norepinephrine displayed a significantly higher percentage change from baseline to peak levels for oligomenorrheic and amenorrheic runners than for eumenorrheic runners and sedentary women. This latter finding is consistent with the hypothesis that periodic marked elevations in norepinephrine levels during maximal exercise may interfere with pulsatile luteinizing hormone release and hence may play a role in the occurrence of menstrual dysfunction in women runners.

Older White Women Run No Increased Risk of Poor Birth Outcomes

Older White Women Run No Increased Risk of Poor Birth Outcomes

Low profiles of salivary progesterone among college undergraduate women

High incidences of amenorrhea and oligomenorrhea are often found among late adolescent, college-aged women. We studied menstrual profiles of salivary progesterone in 17 undergraduate women (average age 20.2 years) who were experiencing regular menstrual cycles, and compared the results with similar data obtained from older women, both recreational runners (30.7 years) and nonexercising controls (29.3 years), to see whether this late adolescent population showed evidence of compromised luteal function not manifested by menstrual irregularity. The profiles obtained from the undergraduates and the older women were similar in shape but different in level. The undergraduate profiles were significantly lower than the controls (average progesterone level during the luteal phase, 154 ± 14 versus 287 ± 30 pmol/L; peak progesterone level, 352 ± 35 versus 655 ± 46 pmol/L; mean ± SE, p < 0.01), and remained at a significantly elevated level for fewer days (1.3 ± 0.4 versus 4.5 ± 0.6 days, p < 0.01). The undergraduates were more comparable in all measures to the older women runners; however, reported exercise and weight differences did not account for the low levels in the undergraduates. We suggest that the low progesterone levels in the undergraduates reflect an extended process of ovarian maturation that does not culminate until the mid to late twenties.

Nutritional survey of highly trained women runners

Mean daily intakes from 3-day dietary records for calories, energy-providing nutrients, and selected minerals were calculated for 51 highly trained women runners. Selected blood constituents relating to mineral status were also measured. Intakes of calcium, magnesium, iron, and copper were above the amounts recommended by the National Research Council whereas zinc intake was below the recommended dietary allowances (RDA). Caloric intakes, although above the RDA for sedentary women, appeared low for women running 10 miles/day. Concentrations of serum ferritin and plasma zinc were indicative of marginal iron and zinc status in many of the women. Whether the nutrient content of the diets consumed by these women is adequate relative to energy output or whether training lowers nutrient requirements by enhancing metabolic efficiency will require further investigation.

Nutritional intakes and status of highly trained amenorrheic and eumenorrheic women runners

This study was conducted to determine whether nutritional status contributes to the amenorrhea associated with long distance running. Dietary intakes and biochemical measures of nutritional status were compared in highly trained amenorrheic (AM) and eumenorrheic (EU) women runners matched for height, weight, percent fat (11% to 12%) and training distance (113 km/week). Serum estradiol (E2) (EU, 104.7 pg/ml, versus AM, 22.5 pg/ml) and cortisol (EU, 22.4 micrograms/dl, versus AM, 26.6 micrograms/dl) concentrations differed between the two groups. Three-day dietary records revealed that fat intake by AM runners was significantly lower than by EU runners (EU, 97 gm/day, versus AM, 66 gm/day). AM runners consumed large amounts of vitamin A activity, probably in the form of B-carotene, and fairly high quantities of crude fiber. Zinc intake by AM runners was well below the recommended dietary allowances (RDA), compared with EU runners (EU, 15.4 mg, versus AM, 10.9 mg). Further, plasma zinc tended to be lower for the AM runners (EU, 85.7 micrograms/dl, versus AM, 81.2 micrograms/dl). It was concluded that the potential contributions of dietary fat, B-carotene, and zinc to inducing changes in menstrual function and the metabolism of certain hormones should be investigated.

Skeletal muscle lactate dehydrogenase isozyme alterations in men and women marathon runners.

Total lactate dehydrogenase (LD) and LD isozyme activities in gastrocnemius muscle from trained men and women runners were measured in response to the chronic stress of training for a marathon race (42.2 km). Following 9 wk of training, total LD activity in skeletal muscle from men and women runners significantly (P less than 0.02) decreased 2.26 and 2.25 U/mg protein, respectively. However, men's total LD activities were significantly (P less than 0.001) less than the women's both before and after training. Significant (P less than 0.05) increases in LD1 activities in skeletal muscle in men and women runners were also observed after training. No significant correlations were detected between percent fiber type composition in men or women vs. the changes in total LD activity, changes in LD1 activity, maximal O2 consumption or training distance averaged per week after the training period. The biochemical adaptations in skeletal muscle that occurred in the LD isozyme composition in both men and women runners make the runners skeletal muscle appear similar to heart muscle in LD1 and LD2 activities.

Increased cortisol production in women runners.

Because we previously found increased basal serum cortisol levels in women runners, we examined adrenocortical function in amenorrheic running women (AR), eumenorrheic running women (R), and normal nonexercising women (NC) in further detail. Mean 24-h urinary cortisol levels were significantly elevated (P less than 0.001) in six AR [45.1 +/- 7.2 (+/- SEM) micrograms/24 h] and eight R (38.5 +/- 6.9 micrograms/24 h) compared to four NC (13.9 +/- 2.8 micrograms/24 h). After adrenal suppression with 2 mg dexamethasone, integrated responses and absolute maximal elevations in serum cortisol levels in response to 10 micrograms/m2 exogenous ACTH (1-24) administered as an iv bolus dose, were not significantly different among six AR, six R, and six NC. This dose of ACTH results in maximal steroid release. The disappearance rates of cortisol (5 mg, iv) after dexamethasone suppression were similar in four AR, five R, and four NC and corresponded to a two-compartment model with mean half-lives of 4.9 and 93.8 min, respectively. Cortisol-binding globulin levels were also similar among the groups. These data document higher cortisol secretion and suggest increased ACTH secretion in running women.

Effect of alcohol intake and exercise on plasma high-density lipoprotein cholesterol subfractions and apolipoprotein A-I in women

Abstinence from alcohol consumption for 3 weeks was followed by 3 weeks of wine intake in 18 inactive and 18 physically active premenopausal women (runners). The runners weighed less and had higher plasma high-density lipoprotein (HDL) cholesterol and lower low-density lipoprotein cholesterol levels than the inactive women. There were no differences between groups in plasma total cholesterol, triglyceride and apolipoprotein A-I concentrations. Runners had higher plasma HDL 2 cholesterol concentrations than inactive women (34 ± 17 vs 19 ± 12 mg/dl), but HDL 3 cholesterol concentration did not differ between the groups (41 ± 10 vs 39 ± 9 mg/dl). Addition of 35 g/day of ethanol for 3 weeks did not result in a significant change in either group for any of the variables measured. The amount of exercise appears to be a more important determinant of plasma lipoproteins and apolipoprotein A-I than alcohol intake in premenopausal women.

Moderate recreational running is associated with lowered salivary progesterone profiles in women

Salivary progesterone profiles were studied in a group of recreational women runners (average 12.5 miles per week) and nonexercising control subjects. Although no differences were observed in the average cycle lengths of the two groups, luteal progesterone levels, both peak and average, were found to be significantly lower in the runners. A salivary progesterone level two standard deviations above the follicular phase average was used to discriminate luteal activity with 95% confidence. Runners averaged fewer days with sample values two standard deviations above this level and a shorter average interval between first and last samples observed above this level. However, no evidence was found of a delayed luteal progesterone rise among the runners. These results suggest that even moderate amounts of aerobic exercise may have effects on female reproductive function which would not be suspected from menstrual patterns alone.

Poor iron status of women runners training for a marathon.

The iron status of nine female marathon runners was evaluated during 11 weeks of training for a marathon race and following a marathon race. Venous blood samples were obtained at the start of the training period, weekly during training, and 1, 2, 3, and 4 days post-race. The subjects completed menstrual and dietary histories, and the diet content of energy, protein, iron, and ascorbic acid was calculated. Serum iron, total iron binding capacity, and transferrin saturation showed no significant change at weeks 1, 7, and 11 during training. The mean values of serum iron and transferrin saturation were low. During training, eight of the nine women averaged serum ferritin levels below 50 ng/ml, one of the eight having values consistently less than 10 ng/ml. Ferritin values were significantly elevated for 3 days after the marathon. No subject reported abnormally heavy menstrual bleeding, and nutrient intakes were near recommended levels, except for iron. Thus, the iron status of these women marathon runners was poor, suggesting that women runners may have higher dietary needs for iron than sedentary women. Serum ferritin levels were also elevated after a marathon run and may not adequately reflect iron stores.

The effect of acute exercise on pulsatile release of luteinizing hormone in women runners

Endurance exercise has been associated with reproductive dysfunction. We have previously suggested that pulsatile release of luteinizing hormone is impaired at rest in normal menstruating runners compared with sedentary women. To determine whether acute exercise had any effect on pulsatile release of luteinizing hormone we investigated serum luteinizing hormone levels in six normal menstruating runners at rest and after 60 minutes of running exercise. Exercise induced an increment in circulating luteinizing hormone levels greater than the change in hematocrit. The luteinizing hormone pulse frequency, calculated as the number of luteinizing hormone pulses per 6 hours, was reduced after exercise compared with values obtained at rest. There was no significant difference in pulse amplitude or area under the 6-hour curve between resting and postexercise situations. These data suggest that acute exercise has an inhibitory effect on luteinizing hormone pulsatile release at the hypothalamic level in eumenorrheic runners that is in addition to the previously described effect of training.

Biomechanical Profile of Elite Women Marathoners

Extensive study has been done on male subjects dealing with gait analysis, but similar investigations of women runners are limited. The purpose of this study was to quantify the essential characteristics and alterations in gait mechanics of women marathoners. Forty elite women marathoners were filmed at four camera locations during the first U.S. Olympic Women's Marathon Trial. Data were quantified with a microcomputer and digitizing system. Quantification of 11 kinematic and temporal variables of gait were obtained. Five variables were examined bilaterally to determine degree of symmetry. Results showed remarkably consistent characteristics of gait across the four camera locations. However, substantial changes did occur between the third and fourth camera locations in stride length and horizontal velocity. All subjects displayed little asymmetry throughout the race. Minimal differences between the top and bottom 10 finishers were noted. There are differences between the gait patterns of men and women distance runners. Stride length, support/nonsupport time ratio, and percent overstride appear to be important factors for success of women distance runners. Most alterations in gait mechanics appear to occur between the 20- and 24-mile marks of the marathon.

Health Concerns of Women Runners

The medical concerns of women runners focus not only on injury but also on how their activity affects their overall health. This article discusses lifestyle and nutritional patterns, menstrual change in active women, amenorrhea and decreased bone density, and issues related to pregnancy. Research data as well as recommendations for the clinician are included.

Serum carotene levels in female long-distance runners

Hypercarotenemia has been associated with anorexia nervosa and hypothalamic amenorrhea. With the emergence of a spectrum of menstrual dysfunction, including anovulation in women runners, the hypothesis of hypothalamic amenorrhea in these patients has been formulated. Other authors have proposed exercise-associated amenorrhea to be distinct from hypothalamic amenorrhea based on endocrine profiles. Using carotene as an index test of hypothalamic amenorrhea, we have studied female long-distance runners (greater than 25 miles/week) and have found no difference in the carotene levels between ovulatory (midfollicular) and anovulatory runners. These data support other evidence that exercise-associated amenorrhea is distinct from hypothalamic amenorrhea.

Twenty Four-Hour Prolactin Profiles and Prolactin Responses to Dopamine in Long Distance Running Women*

Long distance women runners have a high incidence of oligoamenorrhea. In order to study the possible role of PRL in contributing to their menstrual dysfunction, we evaluated PRL secretion in eumenorrheic (n = 7) and oligomenorrheic runners (n = 9) who averaged 25-50 miles/week, as well as nonrunning women (n = 5) during the midfollicular phase of their cycles. Serum estradiol, progesterone, testosterone, FSH, LH, TSH, and T4 were similar among the three groups. The mean 24-h +/- SE PRL concentrations between the three groups: nonrunners, 12.9 +/- 0.6 ng/ml; eumenorrheic runners, 13.5 +/- 0.4 ng/ml; and oligomenorrheic runners, 15.0 +/- 0.8 ng/ml, were not significantly different. A dopamine (DA) infusion, 0.004 micrograms/kg X min, produced physiologic serum DA levels in these subjects. The nadir of serum PRL levels during DA infusion was similar in each group, which argues against an abnormality in dopaminergic tone in the runners with menstrual dysfunction. Our findings of normal 24-h PRL secretion and appropriate PRL responses to DA in women runners with menstrual dysfunction do not support a role for PRL in this disorder.

Reduced Serum Testosterone and Prolactin Levels in Male Distance Runners

To investigate whether endurance running in men produced basal hormonal changes similar to those reported in women, we obtained blood samples from 31 men running at least 64 km each week and 18 sedentary controls for measurement of levels of total testosterone, non-sex hormone-binding globulin-bound and free testosterone, luteinizing hormone, follicle-stimulating hormone, prolactin, and cortisol. The mean levels of total and nonspecifically bound testosterone as well as prolactin were significantly lower than in controls, although levels remained within the physiological range. Other hormone levels were similar in both groups. The lowered testosterone and prolactin levels parallel the changes reported in women runners.