Hormone responses to resistance vs. endurance exercise in premenopausal females

Androgenic Steroid Hormones and Endurance Exercise in Athletic Women

This study investigated the impact of intensive endurance exercise on circulating androgenic steroid hormones in women. Fifteen normally menstruating athletic women participated. They completed intensive endurance exercise (treadmill running) until volitional fatigue in their follicular phase, with blood samples collected at pre-exercise, volitional fatigue, 90 min and 24 h into recovery. The steroid hormones (total, free testosterone, dehydroepiandrosterone [DHEA], and DHEA-sulfate [DHEA-S], cortisol) were analyzed in blood sera. Non-parametric statistics were used to assess changes across exercise and recovery. At volitional fatigue, all hormones, except free testosterone, were significantly (p < 0.05) increased compared to pre-exercise levels. Most hormones remained elevated through 90 min of recovery, with DHEA, DHEA-S, and total testosterone changes being significant (p < 0.05). At 24 h of recovery, hormonal levels were reduced; specifically, DHEA, DHEA-S, and total testosterone compared to baseline (p < 0.01 to 0.06). Increases in cortisol levels at volitional fatigue and 90 min of recovery were correlated with reductions in total testosterone, DHEA, and DHEA-S observed at 24 h of recovery (rho > -0.62, p < 0.05). In conclusion, in menstruating women performing intensive endurance exercise during their follicular phase, their androgenic steroid hormones remain elevated during early recovery but are suppressed at 24 h of recovery. The latter finding indicates that establishing a resting endocrine equilibrium requires a longer recovery period than 24 h.

Exercise-related changes in the anabolic index (testosterone to cortisol ratio) and serum amyloid A concentration in endurance and racehorses at different fitness levels

Increased training loads in both human and equine athletes are generally implemented to improve their physical performance. These loads are tolerated only within appropriate training periodization with regard to recovery time. Otherwise, training overload causes failure in the systemic adaptation, which at first leads to overreaching, and progressively to overtraining syndrome (OTS). Exercise endocrinology, and anabolic/catabolic balance as an indicator of athlete performance status and OTS has continued to attract attention. In human medicine, changes in testosterone and cortisol levels, as well as the testosterone to cortisol ratio (T/C; anabolic index), are suggested to be sensitive stress markers. However, there is a lack of research investigating these parameters for use in equine sports medicine. The aim of the study was to investigate the differences in testosterone, cortisol, and T/C in response to a single training session in two types of equine sports: endurance and race, together with serum amyloid A (SAA), the main acute phase response indicator of physical effort, and the overall health status in horses. Two groups of horses were enrolled in the study: endurance (n = 12) and racehorses (n = 32) of different fitness level. Blood samples were obtained before and after the exercise. On average, T increased 2.5 times after the race training in experienced racehorses and dropped in endurance horses regardless the fitness level (p < 0.05). In endurance horses, a decrease in T/C occurred after training in inexperienced horses (p < 0.05). In racehorses, a T/C decrease occurred in the inexperienced group (p < 0.05) and an increase in the experienced (p < 0.01). In conclusion, T/C ratio was found to be a potentially reliable indicator of fitness status especially in racing horses. These findings provide insight into the physiological response of the horses to different types of exercise and the potential use of hormone levels as markers of performance and adaptation.

The non-modifiable factors age, gender, and genetics influence resistance exercise

Muscle mass and force are key for movement, life quality, and health. It is well established that resistance exercise is a potent anabolic stimulus increasing muscle mass and force. The response of a physiological system to resistance exercise is composed of non-modifiable (i.e., age, gender, genetics) and modifiable factors (i.e., exercise, nutrition, training status, etc.). Both factors are integrated by systemic responses (i.e., molecular signaling, genetic responses, protein metabolism, etc.), consequently resulting in functional and physiological adaptations. Herein, we discuss the influence of non-modifiable factors on resistance exercise: age, gender, and genetics. A solid understanding of the role of non-modifiable factors might help to adjust training regimes towards optimal muscle mass maintenance and health.

Linking Physical Activity to Breast Cancer via Sex Hormones, Part 1: The Effect of Physical Activity on Sex Steroid Hormones

The effect of physical activity on breast cancer risk may be partly mediated by sex steroid hormones. This review synthesized and appraised the evidence for an effect of physical activity on sex steroid hormones. Systematic searches were performed using MEDLINE (Ovid), EMBASE (Ovid), and SPORTDiscus to identify experimental studies and prospective cohort studies that examined physical activity and estrogens, progestins, and/or androgens, as well as sex hormone binding globulin (SHBG) and glucocorticoids in pre- and postmenopausal women. Meta-analyses were performed to generate effect estimates. Risk of bias was assessed, and the GRADE system was used to appraise quality of the evidence. Twenty-eight randomized controlled trials (RCT), 81 nonrandomized interventions, and six observational studies were included. Estrogens, progesterone, and androgens mostly decreased, and SHBG increased, in response to physical activity. Effect sizes were small, and evidence quality was graded moderate or high for each outcome. Reductions in select sex steroid hormones following exercise supports the biological plausibility of the first part of the physical activity-sex hormone-breast cancer pathway. The confirmed effect of physical activity on decreasing circulating sex steroid hormones supports its causal role in preventing breast cancer.See related reviews by Lynch et al., p. 11 and Drummond et al., p. 28.

Caffeine added to coffee does not alter the acute testosterone response to exercise in resistance trained males

BACKGROUND

This study investigated the effects of coffee ingestion with supplemental caffeine (CAF) on serum testosterone (T) responses to exercise in recreationally strength-trained males.

METHODS

Subjects ingested 6 mg/kg body weight of caffeine via 12 ounces of coffee (CAF) supplemented with anhydrous caffeine or decaffeinated (DEC) coffee prior to exercise in a randomized, within-subject, crossover design. The exercise session consisted of 21 minutes of high-intensity interval cycling (alternating intensities at power outputs associated with 2.0 mmol/L lactate for two minutes and 4.0 mmol/L lactate for one minute) followed by resistance exercise (seven exercises, three sets of ten repetitions, 65% 1RM, one-minute rest periods). Subjects also completed repetitions to fatigue tests and soreness scales to determine muscle recovery 24 hours following the exercise.

RESULTS

T was elevated immediately and 30-minutes post-exercise by 20.5% and 14.3% respectively (P<0.05). There was no main effect for treatment and no exercise x treatment interaction. There were no differences in repetitions to fatigue or soreness between treatments (P>0.05). No relationships were observed between T and any proxy of recovery.

CONCLUSIONS

While past literature suggests caffeine may enhance T post-exercise, data from the current study suggest that augmented T response is not evident following anhydrous caffeine added to coffee. The duration of T elevation indicates that this protocol is beneficial to creating long-lasting increases in serum testosterone.

Gender differences in the association between physical activity and cognitive function in individuals with bipolar disorder

INTRODUCTION

Bipolar disorder (BD) is accompanied by a high number of comorbidities and associated with an overall increased mortality. Especially obesity, systemic inflammatory processes and cognitive deficits are highly prevalent and increase with the course of illness. Physical activity (PA) is associated with beneficial effects on somatic comorbidities such as obesity or cardiovascular disease in individuals without psychiatric disorder. Furthermore, PA might increase neurocognitive performance and reduce systemic inflammation.

OBJECTIVE

The aim of the study was to investigate the association between PA and neurocognitive function in euthymic individuals suffering from BD.

METHODS AND PARTICIPANTS

120 individuals with BD, euthymic at test time, completed the self-reported International Physical Activity Questionnaire (IPAQ) assessing PA of the past seven days and were accordingly assigned to a specific activity category (low, moderate or vigorous). Furthermore, clinical parameters were gathered and cognitive tests analysing verbal-dependent intelligence, attention, executive functioning as well as memory were administered.

RESULTS

Female individuals in the vigorous PA group performed significantly higher in most of the cognitive domains compared to females with moderate or low PA. In males, we only found a significant difference in one test for attention between moderate/vigorous and the low activity group.

CONCLUSION

Differences between PA groups in cognitive performance in female individuals with BD were obvious in almost all cognitive domains. As cognitive deficits are strongly associated with a worse course of disease and outcome, PA might offer a concomitant therapy targeting not only somatic comorbidities such as obesity and cardiovascular disease, but also neurocognition.

Postprandial hormone response after endurance or resistance exercise in obese women

Physiological changes with endurance exercise (EE) and resistance training (RT) are likely influenced by the metabolic and hormonal response to each exercise bout, but may be blunted in obese individuals. To compare acute effects of EE, RT, and a control upon hormonal changes in obese women, sedentary, obese women (n=12) participated in a randomised crossover-design study on 3 occasions. EE consisted of treadmill walking (65% VO2max for 1 h). A total-body RT workout consisted of 3 sets of 10 repetitions, 90 s rest for 8 exercises at 90-100% of 10RM. Blood samples were taken 30 min before exercise (0 min), 30 min post-exercise (120 min), and again at 200, 280, and 520 min to assess changes in growth hormone (GH), cortisol, and insulin throughout the postprandial period. A 20 kcal/kg fat-free mass (FFM) meal was given after post-exercise blood sample. There was a main effect of condition for GH ΔAUC (change in area under the curve), with both RT and EE significantly different from the control (RT = 463.0±138.2; EE = 243.2±131.6; Control = -90.4±157.6 ng/ml * 400 min, P<0.02, Control vs EE, effect size (ES) = 2.3; Control vs RT, ES=3.7; EE vs RT, ES=1.6). There were no condition effects for cortisol or insulin ΔAUC. There were no significant time-by-condition interactions for any variables. In obese women, circulating GH concentration is enhanced in the postprandial state following a single bout of either EE or RT, with the GH response being more robust than cortisol or insulin. As circulating GH has shown to be reduced in obesity, the present observations could be considered beneficial, particularly alongside the absence of enhanced cortisol level after exercise.

Effect of exercise intensity on weight changes and sexual hormones (androstenedione and free testosterone) in female rats with estradiol valerate-induced PCOS

Introduction

Weight gain and fat accumulation are predisposing factors of PCOS. Life-style modification, including increasing physical activity, is the first line approach in managing PCOS. The objective of this study is to assess the effect of exercise intensity on weight changes, androstenedione and free testosterone level in female rats with estradiol valerate induced PCOS.

Method and materials

40 female Wistar rats were selected (180 ± 20 g). They had every 2 to 3 consecutive estrous cycles during 12 to 14 days. The study was approved by ethical committee of Jahrom University of Medical Sciences. The first two groups were divided into control (n = 10) and polycystic (n = 30) that were induced PCOS by estradiol valerate injection after 60 days. The polycystic groups were divided into three groups of sham (n = 10), experiment group with low-intensity exercise (pco + l.exe) (n = 10) and experiment group with moderate intensity exercise (pco + m.exe) (n = 10). Exercises were performed during 6 sessions of 60 minutes per week for 8 weeks. (Moderate intensity: 28 m/min-70%–75%VO2Max. Low intensity (20 m/min-50%–55%VO2Max) running at 0 slope, 1 h/day, 6 days/week). ANOVA and LSD test were used for data analysis.

Results

In the present study, no significant differences were found in the decrease of total weights of rats. And also androstenedione level changes in experiment groups were higher compared to control group but no significant differences were found, also free testosterone level was significantly higher than the observer group.

Conclusion

According to weight changes and sexual hormones (Free testosterone and androstenedione) exercise training especially with low intensity may improve symptoms of polycystic ovary syndrome.

Response of testosterone to prolonged aerobic exercise during different phases of the menstrual cycle

PURPOSE

To examine the androgen response to exercise in women under conditions of high (H) and low (L) estrogen (E2) levels.

METHODS

Ten exercise trained eumenorrheic women (mean ± SD: 20.0 ± 2.2 years, 58.7 ± 8.3 kg, 22.3 ± 4.9 % body fat, VO2max = 50.7 ± 9.0 mL/kg/min) completed a 60 min treadmill run at ~70 % of VO2max during both the mid-follicular (L-E2, 69.7 ± 7.3 % VO2max) and mid-luteal (H-E2, 67.6 ± 7.9 % VO2max) phases of their menstrual cycle. Blood samples were taken pre-exercise (PRE), immediately post (POST), and 30 min into recovery (30R) from exercise and analyzed for total testosterone using ELISA assays. Results were analyzed using repeated measures ANOVA.

RESULTS

Testosterone responses were (mean ± SD: L-E2, pre = 1.41 ± 0.21, post = 1.86 ± 0.21, 30R = 1.75 ± 0.32 nmol/L; H-E2, pre = 1.27 ± 0.23, post = 2.43 ± 0.56, 30R = 1.69 ± 0.34 nmol/L). Statistical analysis indicated no significant interaction existed between high and low estrogen conditions across the blood sampling times (p = 0.138). However, a main effect occurred for exercise (p < 0.004) with the post-testosterone concentration being greater than pre, although pre vs. 30R was not different (p > 0.05). All testosterone hormonal concentrations immediately post-exercise greatly exceeded the level of hemoconcentration observed during the L-E2 and H-E2 exercise sessions.

CONCLUSIONS

Prolonged aerobic exercise induces short-term elevations in testosterone in trained eumenorrheic women, which appears unrelated to estrogen levels and menstrual cycle phase. These increases may occur due to either increased androgen production and/or decreased degradation rates of the hormone, and are not solely the result of plasma fluid shifts from the exercise.

The effect of endogenous estrogen on Doppler-estimated right ventricular systolic pressure during exercise

We evaluated the effect of endogenous estrogen levels on exercise-related changes in right ventricular systolic pressure (RVSP) of healthy, eumenorrheic, sedentary women. Volunteers were studied at two separates phases of the menstrual cycle (LO and HI estrogen phases), exercised on a semi-supine ergometer with escalating workload and monitored continuously by 12-lead ECG and automated blood pressure cuff. At each exercise stage, Doppler echocardiography measurements were obtained and analyzed to determine RVSP. Fourteen subjects (age 24 ± 5) were studied. Exercise duration was significantly higher on the HI estrogen day, but no significant differences in hemodynamic response to exercise were found between the two study days. There were also no significant differences with respect to heart rate (HR) acceleration during early exercise, as well as resting and peak RVSP, HR, blood pressure, and rate pressure product. Doppler-estimated RVSP demonstrated a linear relationship to HR at a ratio of 1 mm Hg (1 mm Hg = 133.3224 Pa) for every 5 bpm (beats per minute) increase in HR. There were no differences in the slope of this relationship between HI and LO estrogen phases of the menstrual cycle. Our findings did not demonstrate any effect of endogenous estrogen levels on the modulation of the pulmonary vascular response to exercise in healthy women.

The effect of 12 weeks of resistance training on hormones of bone formation in young sedentary women

Physical activity has been proposed as one strategy to enhance bone mineral acquisition; however, the basic mechanisms of this effect are not fully understood. The purpose of this study was to investigate the effect of 12 weeks of resistance training on hormones of bone formation in young sedentary women. Twenty sedentary females (aged 25.3 ± 3.2 years; ±SD) volunteered to participate in this study. The subjects were randomly assigned to a training group (n = 10) or control group (n = 10). Subjects executed eight resistance exercises selected to stress the major muscle groups in the following order: chest press, leg extension, shoulder press, leg curls, latissimus pull down, leg press, arm curls, and triceps extension. Resistance training consisted of 50-60 min of circuit weight training per day, 3 days a week, for 12 weeks. This training was circularly performed in eight stations and included two to four sets with 8-12 maximal repetitions at 65-80 % of one-repetition maximum in each station. After 12 weeks, the training group had a significant increase (P < 0.05) in the growth hormone, estrogen, parathyroid hormone and testosterone compared to the control group. The results showed that insulin-like growth factor I levels did not change significantly in response to resistance training. In conclusion, the results suggest that resistance training with specific intensity and duration utilized in this study increases the hormones of bone formation in young sedentary women.

The role of androgens and estrogens on healthy aging and longevity

Aging is associated with a loss of sex hormone in both men (andropause) and women (menopause). In men, reductions in testosterone can trigger declines in muscle mass, bone mass, and in physical function. In women, the impact of the loss of sex hormones, such as estradiol, on bone is well elucidated, but evidence is limited on whether the loss of estradiol negatively affects muscle mass and physical function. However, deficiencies in multiple anabolic hormones have been shown to predict health status and longevity in older persons. Thus, consideration should be given as to whether targeted hormone replacement therapies may prove effective at treating clinical conditions, such as age-related sarcopenia, cancer cachexia, and/or acute or chronic illnesses. If initiated carefully in the appropriate clinical population, hormone replacement therapies in men and women may prevent and reverse muscle and bone loss and functional declines and perhaps promote healthy aging and longevity.

Neuroendocrine-immune interactions and responses to exercise

This article reviews the interaction between the neuroendocrine and immune systems in response to exercise stress, considering gender differences. The body's response to exercise stress is a system-wide effort coordinated by the integration between the immune and the neuroendocrine systems. Although considered distinct systems, increasing evidence supports the close communication between them. Like any stressor, the body's response to exercise triggers a systematic series of neuroendocrine and immune events directed at bringing the system back to a state of homeostasis. Physical exercise presents a unique physiological stress where the neuroendocrine and immune systems contribute to accommodating the increase in physiological demands. These systems of the body also adapt to chronic overload, or exercise training. Such adaptations alleviate the magnitude of subsequent stress or minimize the exercise challenge to within homeostatic limits. This adaptive capacity of collaborating systems resembles the acquired, or adaptive, branch of the immune system, characterized by the memory capacity of the cells involved. Specific to the adaptive immune response, once a specific antigen is encountered, memory cells, or lymphocytes, mount a response that reduces the magnitude of the immune response to subsequent encounters of the same stress. In each case, the endocrine response to physical exercise and the adaptive branch of the immune system share the ability to adapt to a stressful encounter. Moreover, each of these systemic responses to stress is influenced by gender. In both the neuroendocrine responses to exercise and the adaptive (B lymphocyte) immune response, gender differences have been attributed to the 'protective' effects of estrogens. Thus, this review will create a paradigm to explain the neuroendocrine communication with leukocytes during exercise by reviewing (i) endocrine and immune interactions; (ii) endocrine and immune systems response to physiological stress; and (iii) gender differences (and the role of estrogen) in both endocrine response to physiological stress and adaptive immune response.

Circulating androgens in women: exercise-induced changes

Physical exercise is known to strongly stimulate the endocrine system in both sexes. Among these hormones, androgens (e.g. testosterone, androstenedione, dehydroepiandrosterone) play key roles in the reproductive system, muscle growth and the prevention of bone loss. In female athletes, excessive physical exercise may lead to disorders, including delay in the onset of puberty, amenorrhoea and premature osteoporosis. The free and total fractions of circulating androgens vary in response to acute and chronic exercise/training (depending on the type), but the physiological role of these changes is not completely understood. Although it is commonly accepted that only the free fraction of steroids has a biological action, this hypothesis has recently been challenged. Indeed, a change in the total fraction of androgen concentration may have a significant impact on cells (inducing genomic or non-genomic signalling). The purpose of this review, therefore, is to visit the exercise-induced changes in androgen concentrations and emphasize their potential effects on female physiology. Despite some discrepancies in the published studies (generally due to differences in the types and intensities of the exercises studied, in the hormonal status of the group of women investigated and in the methods for androgen determination), exercise is globally able to induce an increase in circulating androgens. This can be observed after both resistance and endurance acute exercises. For chronic exercise/training, the picture is definitely less clear and there are even circumstances where exercise leads to a decrease of circulating androgens. We suggest that those changes have significant impact on female physiology and physical performance.

Hormonal response to Taekwondo fighting simulation in elite adolescent athletes

Exercise training efficiency depends on the training load, as well as on the athlete's ability to tolerate it. The aim of the present study was to evaluate the effect of fighting simulation (3 fights, 6 min each, 30 min rest between fights) on anabolic (IGF-I, LH, FSH, estradiol, and testosterone) and catabolic hormones (cortisol) in elite, male (n = 10) and female (n = 10) adolescent (12-17 years) Taekwondo fighters. Blood samples were collected before the first and immediately after the third fight. The fighting simulation practice led to significant (p < 0.05) decreases in IGF-I (males -27.1 ± 25.6, females -22.4 ± 36.3 ng/ml), LH (males -0.7 ± 1.2, females -2.3 ± 3.3 U/L), and FSH (males -0.9 ± 0.5, females -1.5 ± 1.1 U/L), and to a significant increase (p < 0.05) in cortisol (males 141.9 ± 30.1, females 64.1 ± 30.6 mcg/dL) in both genders. Fighting simulation decreases in testosterone (males -1.9 ± 1.6, females -0.02 ± 0.06 ng/mL), and free androgen index (males -20.1 ± 21.5, females -0.3 ± 0.5) were significant (p < 0.05) only in male fighters. Exercise had no significant effect on estradiol, sex-hormone-binding globulins or thyroid function tests. Our data demonstrate that the physiologic and psychologic strain of a Taekwondo fighting simulation day led to a catabolic-type circulating hormonal response.

Altered DHEA and DHEAS response to exercise in healthy older adults

Dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) are hormones produced by the adrenal cortex that decline in concentration with age. Decreased DHEA levels are associated with age-related disease and oxidative stress but might be increased in younger adults by exercise. Studies are presented assessing the response of DHEA and DHEAS to varied-intensity exercise in older age. DHEA increased significantly in young adults (14.5 +/- 6.1 ng/ml rising to 21.1 +/- 7.5 ng/ml; p < .01), whereas DHEAS decreased significantly (2.56 +/- 1.11 microg/ml falling to 1.90 +/- 0.8 microg/ml; p < .05), after submaximal exercise. DHEA and DHEAS levels were significantly lower in older adults than in younger adults (p < .01), and there was no observed response of either hormone to exercise in older adults. Lipoprotein protein carbonylation is presented as a measure of oxidative status and significantly decreased in younger adults postexercise. Participants with higher DHEA postexercise had lower LDL protein carbonyl concentrations (Pearson's coefficient -.409, p < .05).

Effects of menstrual cycle, oral contraception, and training on exercise-induced changes in circulating DHEA-sulphate and testosterone in young women

The objective of this study was to ascertain the effects of menstrual cycle, oral contraception, and training status on the exercise-induced changes in circulating DHEA-sulphate and testosterone in young women. Twenty-eight healthy women were assigned to an untrained group (n = 16) or a trained group (n = 12) depending on their training background. The untrained group was composed of nine oral contraceptive users (OC+) and seven eumenorrheic women (OC-). The trained group was composed of OC+ subjects only. All the OC+ subjects were taking the same low-dose oral contraception. Three laboratory sessions were organised in a randomised order: a prolonged exercise test until exhaustion, a short-term exhaustive exercise test, and a control session. Blood specimens were collected before, during and after the exercise tests and at the same time of the day during the control session. Basal circulating testosterone was significantly lower in trained as compared to untrained subjects. In all subjects, the prolonged exhaustive exercise induced a significant increase in circulating DHEA-s and testosterone. The short-term exercise induced a significant increase in circulating DHEA-s in untrained eumenorrheic and in trained OC users only. Menstrual phases in OC- did not influence the responses. It was found that exhaustive physical exercise induced an increase in circulating DHEA-s and testosterone in young women. Oral contraception may limit short-term exercise-induced changes.

Nandrolone excretion in sedentary vs physically trained young women

We investigated the effects of the menstrual cycle, oral contraception and physical training on exhaustive exercise-induced changes in the excretion of nandrolone metabolites [19-norandrosterone (19-NA), and 19-noretiocholanolone (19-NE)] in young women. Twenty-eight women were allocated to an untrained group (n=16) or a trained group (n=12), depending on their physical training background. The untrained group was composed of nine oral contraceptive users (OC+) and seven eumenorrheic women (OC-), while the trained group was entirely composed of OC+ subjects. Three laboratory sessions were conducted in a randomized order: a prolonged exercise test, a short-term exercise test and a control session. Urine specimens were collected before and 30, 60 and 90 min after the exercise test and at the same times of the day during the control session. Urinary concentrations of nandrolone metabolites were determined by gas chromatography coupled to mass spectrometry. Urinary concentrations of 19-NA and 19-NE ranged from undetectable levels to 1.14 and 0.47 ng/mL, respectively. Nandrolone excretion was not affected by the menstrual cycle phase (early follicular vs mid-luteal), prior physical training, oral contraception or acute physical exercise. Therefore, a urinary concentration of 2 ng/mL of 19-NA appears to be fair as the upper acceptable limit in doping control tests for female athletes.

Biological factors and the determination of androgens in female subjects

The idea of the presence of androgens in females may sound peculiar as androgens generally refer to male hormones. Although produced in small amounts in women, androgens have direct and significant effects on many aspects of female physiology. Moreover, androgens are precursors to estrogens, which are the predominant female sex hormones. The measurement of androgens in blood is important in the diagnosis of both gonadal and adrenal functional disturbances, as well as monitoring subsequent treatments. The accuracy of such measurements is crucial in sports medicine and doping control. Therefore, the concentration of androgens in female subjects is frequently measured. Analysing such compounds with accuracy is especially difficult, costly and time consuming. Therefore, laboratories widely use direct radioimmunoassay kits, which are often insensitive and inaccurate. It is especially complicated to determine the level of androgens in women, as the concentration is much lower compared to the concentration found in males. Additionally, the amount of androgens in fluids tends to decrease with aging. Analyses of hormone concentrations are influenced by a myriad of factors. The factors influencing the outcome of these tests can be divided into in vivo preanalytical factors (e.g., aging, chronobiological rhythms, diet, menstrual cycle, physical exercise, etc.), in vitro preanalytical factors (e.g., specimen collection, equipment, transport, storage, etc.) and as mentioned before, analytical factors. To improve the value of these tests, the strongly influencing factors must be controlled. This can be accomplished using standardised assays and specimen collection procedures. In general, sufficient attention is not given to the preanalytical (biological) factors, especially in the measurement of androgens in females. Biological factors (non-pathological factors) that may influence the outcome of these tests in female subjects have received little attention and are the topic of the present review.

Possible Stimuli for Strength and Power Adaptation

The endocrine system plays an important role in strength and power development by mediating the remodelling of muscle protein. Resistance training scheme design regulates muscle protein turnover by modifying the anabolic (testosterone, growth hormone) and catabolic (cortisol) responses to a workout. Although resistance exercise increases the concentrations of insulin-like growth factor 1 in blood following exercise, the effect of scheme design is less clear, most likely due to the different release mechanisms of this growth factor (liver vs muscle). Insulin is non-responsive to the exercise stimulus, but in the presence of appropriate nutritional intake, elevated blood insulin levels combined with resistance exercise promotes protein anabolism. Factors such as sex, age, training status and nutrition also impact upon the acute hormonal environment and, hence, the adaptive response to resistance training. However, gaps within research, as well as inconsistent findings, limit our understanding of the endocrine contribution to adaptation. Research interpretation is also difficult due to problems with experimental design (e.g. sampling errors) and various other issues (e.g. hormone rhythms, biological fluid examined). In addition to the hormonal responses to resistance exercise, the contribution of other acute training factors, particularly those relating to the mechanical stimulus (e.g. forces, work, time under tension) must also be appreciated. Enhancing our understanding in these areas would also improve the prescription of resistance training for stimulating strength and power adaptation.

Prior endurance exercise attenuates growth hormone response to subsequent resistance exercise

This study examined the influence of prior endurance exercise on hormonal responses to subsequent resistance exercise. Ten males exercised on a cycle ergometer at 50% of maximal oxygen uptake for 60 min and subsequently completed a resistance exercise (bench and leg press, four sets at ten repetitions maximum with an interset rest period of 90 s). Alternatively, the subjects performed the protocol on a separate day with prior endurance exercise limited to 5 min. Blood was obtained before and after the endurance exercise, and 10, 20, and 30 min after the resistance exercise. Maximal isometric torque measured before and after endurance and resistance exercises showed no significant difference between trials. No significant difference was seen in the concentrations of glucose, lactate, testosterone, and cortisol between the trials, but free fatty acids (FFA) and growth hormone (GH) increased (P<0.01 and P<0.05, respectively) after 60 min of endurance exercise. Conversely, after the resistance exercise, GH was attenuated by 60 min of prior exercise (P<0.05). These results indicate that the GH response to resistance exercise is attenuated by prior endurance exercise. This effect might be caused by the increase in blood FFA concentration at the beginning of resistance exercise.

Effect of training status and exercise mode on endogenous steroid hormones in men

The purpose of this study was to determine the acute anabolic and catabolic hormone response to endurance and resistance exercise bouts of equal volume in subjects with differing training status. Twenty-two healthy men were recruited who were either resistance trained ( n = 7), endurance trained ( n = 8), or sedentary ( n = 7). Three sessions were completed: a resting session, a 40-min run at 50-55% maximal oxygen consumption, and a resistance exercise session. Expired gases were monitored continuously during exercise, and the endurance and resistance exercise sessions were individually matched for caloric expenditure. Blood samples were drawn before exercise and 1, 2, 3, and 4 h after the start of the exercise. Plasma was analyzed for luteinizing hormone, dehydroepiandrosterone sulfate, cortisol, and free and total testosterone. Androgens increased in response to exercise, particularly resistance exercise, whereas cortisol only increased after resistance exercise. Dehydroepiandrosterone sulfate levels increased during the resistance exercise session and remained elevated during recovery in the resistance-trained subjects. Endurance-trained subjects displayed less pronounced changes in hormone concentrations in response to exercise than resistance-trained subjects. After an initial postexercise increase, there was a significant decline in free and total testosterone during recovery from resistance exercise ( P < 0.05), particularly in resistance-trained subjects. On the basis of the results of this study, it appears that the endogenous hormone profile of men is more dependent on exercise mode or intensity than exercise volume as measured by caloric expenditure. The relatively catabolic environment observed during the resistance session may indicate an intensity-rather than a mode-dependent response.

Anabolic Hormones in Aging Women: Effects of Supplementation vs. Physical Activity

Aging is associated with a decline in bone mass, muscle mass, strength, and physical function, and women are more likely to suffer from these physical changes than men. The model presented in this paper illustrates the age related changes in anabolic hormones and how this may partly explain the diminished physical function of older women. The model can also be used to identify potential sites of intervention that could delay the atrophy of the musculoskeletal system. Various pharmacological hormone therapies have been shown to be beneficial, but there may be health risks associated with their use. There is evidence that regular physical activity is related to higher levels of anabolic hormones in older persons, therefore exercise could be an alternative to drugs for slowing the age related changes in the endocrine system. However, some research suggests that the hormone response to exercise is blunted in older women. This lower hormonal response may not be a consequence of aging per se but instead may result from secondary characteristics of aging such as a decline in physical fitness and exercise intensity or changes in body composition. Further research is needed to determine whether exercise-induced increases in endogenous hormones have clinical significance in improving muscle or bone mass in aging women. Key words: hormone replacement therapy, exercise, sex steroids, growth hormone, IGF-I

Aging, Physical Activity, and Hormones in Women—A Review

Women experience significant changes in endocrine function during aging. Decreasing levels of anabolic hormones may be associated with musculoskeletal atrophy and decrease in function that is observed in older women and, as a result, there has been an increase in the use of pharmacological hormone therapies. It is difficult to distinguish, however, between physiological changes that are truly age related and those that are associated with lifestyle factors such as physical activity participation. Some research has shown that circulating levels of anabolic hormones such as DHEA(S) and IGF-I in older women are related to physical activity, muscle function, and aerobic power. Exercise-intervention studies have generally shown that increasing age blunts the acute hormonal response to exercise, although this might be explained by a lower exercise intensity in older women. There have been relatively few studies that examine hormonal adaptations to exercise training. Physical activity might have an effect on hormone action as a result of changes in protein carriers and receptors, and future research needs to clarify the effect of age and exercise on these other components of the endocrine system. The value and safety of hormone supplements must be examined, especially when used in combination with an exercise program.

Endogenous anabolic hormone responses to endurance versus resistance exercise and training in women

Research in exercise endocrinology has flourished over the past few decades. In general, research examining short- and long-term hormone responses to endurance exercise preceded studies on resistance exercise, and research on women lagged behind research on men. Sufficient data are now available to allow a comparison of endogenous anabolic hormone responses to endurance versus resistance exercise and training in women. Circulating levels of testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulphate, estradiol, growth hormone and cortisol have been shown to increase in response to an acute bout of endurance exercise in women. However, only growth hormone, estradiol and cortisol have been reported to increase following resistance exercise. Hormone changes following training, either endurance or resistance, have been variable, probably because of differences in experimental design and major differences in the length, intensity and volume of training programmes. With the notable exception of growth hormone, the anabolic hormones reviewed here appear to decline with endurance training. Resistance training has little effect on resting hormone levels, except insulin-like growth factor-I, which has been shown to increase following a training programme. These hormone changes potentially have both metabolic and hypertrophic implications, and future research needs to focus on the biological significance of these adaptations.