Brain evoked responses reflect information processing changes with the menstrual cycle in young female athletes

In sport activity, information processing plays a role crucial for sport performance. Neuropsychological and psychophysiological evidence based on behavioral and psychophysical tasks has been accumulated showing that the latter changes over the course of the menstrual cycle, but the available data are rather inconsistent. On the other hand, in sport literature, not much attention has been devoted to these topics by researchers who have mainly been asked to investigate changes in mood and well-being. Therefore, a study has been undertaken to investigate the relationships between the menstrual cycle and information processing in young female athletes, some of whom took oral contraceptives. The study was based on Auditory Evoked Responses that, unlike behavioral and psychophysical techniques, were revealed to be an exceptionally reliable tool for the study of neural activity during sensory information processing. The results showed the existence of clear fluctuations over the course of the menstrual cycle in time taken to handle information and in the amount of information processing that, with differences and similarities, could be observed both in spontaneously menstruating and on-pill athletes. In addition, neuroanatomical differences were evident in the response of different neural structures of the auditory pathways. In fact, the effects of the hormonal changes accompanying the menstrual cycle appear to be more effective and influential at higher central levels of the auditory pathway.     

Neuromuscular performance and knee laxity do not change across the menstrual cycle in female athletes

Female athletes incur anterior cruciate ligament ruptures at a rate at least twice that of male athletes. Hypothesized factors for the increased injury risk in females include biomechanical, neuromuscular, and hormonal differences between genders. A wealth of literature exists examining these potential predispositions individually, but the interactions between these factors have not been examined extensively. Our purpose was to investigate changes in neuromuscular control and laxity at the knee across the menstrual cycle of healthy females. Fourteen female collegiate athletes with normal, documented ovulatory menstrual cycles, confirmed ovulation, and no history of serious knee injury participated. The presence and timing of ovulation was determined during a screening cycle with ovulation detection kits and during an experimental cycle with collection of daily urine samples and subsequent analysis of urinary estrone-3-glucuronide (E3G) and pregnanediol-3-glucoronide (PdG), which correlate with circulating estrogen and progesterone. Each subject had measures of knee neuromuscular performance and laxity once during the mid-follicular, ovulatory, and mid-luteal stages of her menstrual cycle. The test battery included assessments of knee flexion and extension peak torque, passive knee joint position sense, and postural control in single leg stance. Knee joint laxity was measured with an arthrometer. Analyses of variance revealed that E3G and PdG levels were significantly different across the three testing sessions, but there were no significant differences in the measures of strength, joint position sense, postural control, or laxity. No significant correlations were found between changes in E3G or PdG levels and changes in the performance and laxity measures between sessions. These results suggest that neuromuscular control and knee joint laxity do not change substantially across the menstrual cycle of females despite varying estrogen and progesterone levels.     

An effective, economic way of monitoring menstrual cycle hormones in at risk female athletes

PURPOSE: Female athletes, in response to intensive training, competition stress and a lean, athletic physique, are at increased risk of altered hypothalamic-pituitary ovarian (HPO) axis function associated with menstrual cycle disturbance and reduced secretion of the ovarian hormones estrogen and progesterone. Because there is evidence suggesting possible detrimental effects on skeletal health associated with deficiencies in these hormones, a suitable means to asses ovarian hormone concentrations in at risk athletes is needed. The aim of this study was to evaluate a simple, economical means to monitor the ovarian hormone production in athletes, in the setting of intensive training. METHODS: Subjects comprised 14 adolescent rowers, 12 lightweight rowers, and two groups of 10 matched control subjects. Ovarian function was monitored during the competition season by estimation of urinary excretion of estrone glucuronide (E1G) and pregnanediol glucuronide (PdG), enabling the menstrual cycles to be classified as ovulatory or anovulatory. RESULTS: Results indicated 35% and 75% of schoolgirl and lightweight rowers had anovulatory menstrual cycles, respectively. These findings were highlighted by significantly lower excretion of E1G and PdG during phases of intensive training in both the lightweight and schoolgirl rowers, compared with the control subjects. CONCLUSION: It was concluded that the urinary E1G and PdG assays were an effective means to assess the influence of intense training on ovarian hormone concentrations in at risk athletes. It is recommended that this technique be applied more widely as a means of early detection of athletes with low estrogen and progesterone levels, in an attempt to avoid detrimental influences on skeletal health.     

Physiological responses to submaximal exercise at the mid-follicular, ovulatory and mid-luteal phases of the menstrual cycle

This study examined the responses of eumenorrheic women to 60 min of submaximal exercise at the mid-follicular (MF), ovulatory (OV) and mid-luteal (ML) phases of the menstrual cycle. Blood metabolite-hormonal measures, cardiorespiratory responses and ratings of perceived exertion (WE) (local, legs only; and total, entire body) were monitored at 15-min intervals throughout exercise. No significant effects for phase were observed in the blood measures or the cardiorespiratory responses, except for the respiratory exchange ratio (RER). The overall exercise OV RER (0.86 ± 0.02; mean ± SEM) was lower than at MF (0.94 ± 0.02) but not at ML (0.89 ± 0.01). Substrate utilization (%) and oxidation (g/min) calculations indicated that more fat was used during OV than at MF but not ML. Conversely, more carbohydrate was used during MF than OV. Additionally, local RPE was higher in OV than in the MF or ML trials at 30–60 min of exercise. These findings suggest that menstrual cycle hormonal fluctuations influence metabolic substrate usage and effort perception during submaximal exercise in eumenorrheic women.     

Physiological responses to resistance-exercise in athletes self-administering anabolic steroids

Endocrine and metabolic responses to resistance exercise were compared in 5 athletes self-administering (SL) anabolic steroids and 8 athletes (L) not using these compounds. Exercise consisted of 5 sets of 10 repetitions in the squat and quarter squat. Blood samples were collected before (pre) and immediately after (post) exercise, and following 30 minutes of recovery (post-30). Except for significantly lower lactate concentrations in SL (p less than 0.015) at post-30, the responses to exercise and recovery were similar in both groups. Significantly higher hematocrits (p less than 0.0001), total androgen concentrations (p less than 0.0001), and androgen/cortisol ratios (p less than 0.0001) were observed in the SL group across all time periods. Plasma androgen concentrations increased about 22% in SL following exercise, even though plasma LH concentrations were significantly lower (p less than 0.0001) than in L. Plasma ACTH and cortisol concentrations were not significantly affected. Both groups displayed similar endocrine and metabolic responses to an acute bout of resistance exercise. The higher androgen/cortisol ratios and lower plasma lactate concentrations during recovery are two potential factors which may help explain the lower subjective level of fatigue following training sessions often reported by individuals who use anabolic steroids.     

Physiological parameters related to distance running performance in female athletes

The purpose of this study was to investigate the relationship between running pace for the 5 km, the 10 km, and the 16.09 km (10 mile) distances and the following variables: oxygen uptake and treadmill speed at predetermined lactate accumulation points (2.0 and 4.0 mmol.l-1), oxygen uptake (running economy) at three submaximal standardized treadmill speeds (196, 215, and 241 m.min-1), and maximal oxygen uptake. Thirteen moderately to highly conditioned (VO2max = 59.7 +/- 5.3 ml.kg-1.min-1; VO2 at 2.0 mmol.l-1 of plasma lactate = 46.6 +/- 4.1 ml.kg-1.min-1) female runners between the ages of 18 and 33 yr volunteered to participate. All subjects performed the laboratory tests and the 5 km, 10 km, and 16.09 km competitive time trials on an outdoor 5 km course. The correlation coefficients (r) between each race pace and maximal oxygen uptake (VO2max), speed (s) at 2.0 mmol.l-1 plasma lactate accumulation (PLA2s), and speed at 4.0 mmol.l-1 plasma lactate accumulation (PLA4s) ranged between 0.84 and 0.94. The oxygen costs of running at each of the three submaximal paces were correlated moderately with each race pace (r = -0.40 to -0.63). Hierarchal stepwise multiple regression analyses produced equations with two independent variables which explained 94 to 97% of the variability in race performance.     

The menstrual cycle and anterior cruciate ligament injury risk: implications of menstrual cycle variability

The menstrual cycle and associated hormonal fluctuations are considered risk factors for non-contact anterior cruciate ligament (ACL) injuries in female athletes. Researchers have used a 'normal' 28-day cycle and relied upon menstrual history questionnaires or a biological sample (i.e. blood, saliva) taken on a single day to identify the phase of the menstrual cycle where an ACL tear has occurred. However, evidence from available studies lack adequate consideration of menstrual cycle variability that exists in the general population and neglect to acknowledge the greater prevalence of subtle menstrual disturbances in physically active and athletic women. Inter- and intra-woman menstrual cycle variability is large for total cycle, follicular phase and luteal phase length ranging from 22 to 36, 9 to 23 and 8 to 17 days, respectively (95% CI). More importantly, subtle menstrual disturbances such as anovulation and luteal phase defects are common in athletic women with a high prevalence of cycle-to-cycle variations. To complicate matters further, menstrual history questionnaires inaccurately quantify cycle length compared with prospective monitoring of cycle length, highlighting the need to implement more sophisticated methods for identifying menstrual cycle/phase characteristics. Regardless of variability and/or the presence of subtle menstrual disturbances, women may still have regularly occurring menses, making it extremely difficult to accurately identify the phase of the menstrual cycle where an ACL tear has occurred based on a menstrual history questionnaire or a single biological sample. Therefore, the assumption that normal ovarian endocrine function is synonymous with regularly occurring menses in physically active and athletic women is unjustified. Thus, definitive conclusions are not warranted regarding the association between the menstrual cycle and non-contact ACL injury risk based on currently available data. Future work in this area must incorporate methods to prospectively evaluate and accurately characterize menstrual cycle characteristics if we are to link the hormonal fluctuations of the menstrual cycle to non-contact ACL injury risk.     

Physiological and performance responses to overtraining in elite judo athletes

To determine the effect of large and sudden increases in training volume on performance characteristics and the feasibility of using overtraining syndrome symptoms to monitor performance changes, 15 elite judo athletes were examined through 10 wk of training. Athletes performed their regular regimens of resistance (3 d.wk-1), interval (2 d.wk-1), and judo (5 d.wk-1) training in weeks 1-4. Interval and resistance training volumes increased by 50% in weeks 4-8 and returned to baseline in weeks 9-10. Judo training volume was unchanged in weeks 1-8 but increased by 100% in weeks 9-10. Assessments were made in weeks 2, 4, 8, and 10. Isokinetic strength of elbow and knee extensors and flexors increased significantly from weeks 2 to 4 (3-13%), was unchanged from weeks 4 to 8, and decreased significantly (6-12%) from weeks 4 to 10. Total time for 3 x 300 m intervals increased (P less than 0.05) between weeks 2 and 4 and between weeks 4 and 8, while total time for 5 x 50 m sprints decreased (P less than 0.05) from weeks 8 to 10 (less than 2%). Body fat percentage decreased (P less than 0.05) from weeks 2 to 10. Body weight, submaximal and maximal aerobic power, resting (sleeping) systolic and diastolic pressures, resting (sleeping) submaximal and maximal heart rates, exercising blood lactate levels, and vertical jump performance did not change significantly with increases in training volume. These results suggest that 6 wk of overtraining may affect some but not all aspects of performance and that performance may be affected before symptoms of the overtraining syndrome appear.     

Preoccupation with weight and menstrual function in female elite athletes

To determine the self-reported prevalence of menstrual dysfunction in athletes and controls found to be at risk of developing eating disorders (ED) and the factors characterizing and classifying athletes suffering from menstrual dysfunction, the Eating Disorder Inventory (EDI) and a self-developed questionnaire were administered to the total population of Norwegian female elite athletes (n=603) and age- and home community-matched controls (n=522). The response rate in both athletes and controls was 86%. Subjects younger than 16 years who had not attained menarche (29 athletes and 14 controls) and subjects taking contraceptive medication (145 athletes and 131 controls) were excluded. Thus, a total of 348 athletes (19.4±4.3 years) and 303 controls (20.6±4.4 years) were analyzed. A high prevalence of athletes (42%) reported menstrual dysfunction; the prevalence of menstrual dysfunction was significantly different between subjects classified as at risk of developing ED (54% and 36%, for athletes and controls, respectively) and subjects found not to be at risk (41% and 23%, respectively). Furthermore, the prevalence of menstrual dysfunction was significantly higher among athletes competing in sports in which leanness and/or a specific weight are considered important (endurance: 62%, aesthetics: 60% and weight-dependent: 50%) than among athletes competing in sports in which these factors are considered less important (technical: 37%, ballgames: 28% and power sports: 22%). Menarchal age, training volume, body mass index (BMI) and EDI score contributed significantly to explaining menstrual dysfunction in athletes (37%). The authors suggest that athletes reporting menstrual dysfunction could be characterized and classified into 2 main groups: first, the athletes who have a predisposed genetically lean body build (low BMI) and a delayed menarche and undertake hard physical training that does not allow them to achieve the “critical” weight for height found necessary for regular cycles. Secondly, the athletes who have normal BMI, experience menarche at the expected time and who become preoccupied with weight and dieting and/or use of pathogenic weight control methods which then, at least in part, may explain the menstrual dysfunction.     

Comparison of some intrinsic risk factors of shoulder injury in three phases of menstrual cycle in collegiate female athletes

Objectivespresent study aims to investigate the changes in the shoulder joint stability factors during the menstrual cycle.Designcross-sectional study;Settinglaboratory.Participants15 healthy collegiate female athletes with normal menstrual cycles.Main outcome measuresshoulder strength, proprioception, laxity and functional stability were the primary outcomes. Participants were assessed in three phases (mense, ovulation, midluteal (day 21) by 4 different categories of tests, each designed for a different factor. Shapiro-Wilk Test was used to determine normality of data, ANOVA and Friedman Test were used to compare results. Significance level and alpha were considered 95 percent and ≥0.05, respectively. Data shown a relation between proprioception, strength and menstrual cycle.Resultsshoulder strength was significantly increased in ovulation phase compared to other phases (p < 0.5) (effect size >0.14). Proprioception was significantly decreased in luteal phase than in mense and ovulation phases (p < 0.5) (effect size >0.14). Finally, ligament laxity and functional stability showed no change in all phases (p < 0.5).ConclusionMenstrual cycle and sexual hormones affect muscle strength and proprioception of shoulder joint, but have no effect on ligament laxity and functional stability.     

Physiological responses to treadmill and cycle exercise

This study aimed to identify differences in the acute cardio-respiratory, metabolic and perceptual responses between exercise performed on the treadmill and on the cycle ergometer at several intensities. The sample comprised of 20 voluntary male participants (age=22.5 ± 1.8 years; height=177.7 ± 7.0 cm; body mass=72.6 ± 7.9 kg; fat mass=7.87 ± 1.3%) that performed 5 submaximal 8 min exercise bouts, interspersed with a 10 min period of passive recovery. Exercise intensity used on the treadmill was 10, 12, 14, 15 and 16 km/h (0% gradient), and 80, 120, 160, 180 and 200 W on the cycle ergometer (65-70 rpm). There was a significant mode effect and also mode×intensity interaction in oxygen uptake and heart rate with higher values in the treadmill protocol (F=32.0 p=0.000, η2=0.65 and F=132.0 p=0.000, η2=0.88, respectively). The respiratory exchange ratio and blood lactate concentrations were not different across modes (F1, 18=1.9 p=0.183 and F1, 17=0.1 p=0.964, respectively) and rate of perceived exertion values were higher in the cycle ergometer (F1, 12=1.2 p=0.288). Generally, results showed a larger exercise mode effect on the cardio-respiratory variables with higher response patterns on the treadmill, differing according to exercise intensity.     

Introduction to menstrual disturbances in athletes

The first symposium on this topic at an annual meeting of ACSM was presented 22 yr ago when the high prevalence of menstrual disorders in athletes was becoming increasingly apparent. The clinical consequences and need for treatment for menstrual disturbances in athletes have been recognized by ACSM through the publication of its 1997 Position Stand on the Female Athlete Triad. This mini-symposium presents an update on recent scientific advances on this topic. The first review in this symposium concentrates on a menstrual disturbance in which the length of the luteal phase is abbreviated and luteal function is suppressed. Such luteal suppression occurs in a large proportion of even the most regularly menstruating athletes. The next two papers summarize what has been learned about the mechanism of these disturbances from prospective experiments that have employed diet, exercise, cold exposure, and pharmacological blockers of metabolic pathways to disrupt menstrual cycles in monkeys and humans as well as estrous cycles and reproductive behavior in hamsters.     

Physiological and nutritional aspects of post-exercise recovery: specific recommendations for female athletes

Gender-based differences in the physiological response to exercise have been studied extensively for the last four decades, and yet the study of post-exercise, gender-specific recovery has only been developing in more recent years. This review of the literature aims to present the current state of knowledge in this field, focusing on some of the most pertinent aspects of physiological recovery in female athletes and how metabolic, thermoregulatory, or inflammation and repair processes may differ from those observed in male athletes. Scientific investigations on the effect of gender on substrate utilization during exercise have yielded conflicting results. Factors contributing to the lack of agreement between studies include differences in subject dietary or training status, exercise intensity or duration, as well as the variations in ovarian hormone concentrations between different menstrual cycle phases in female subjects, as all are known to affect substrate metabolism during sub-maximal exercise. If greater fatty acid mobilization occurs in females during prolonged exercise compared with males, the inverse is observed during the recovery phase. This could explain why, despite mobilizing lipids to a greater extent than males during exercise, females lose less fat mass than their male counterparts over the course of a physical training programme. Where nutritional strategies are concerned, no difference appears between males and females in their capacity to replenish glycogen stores; optimal timing for carbohydrate intake does not differ between genders, and athletes must consume carbohydrates as soon as possible after exercise in order to maximize glycogen store repletion. While lipid intake should be limited in the immediate post-exercise period in order to favour carbohydrate and protein intake, in the scope of the athlete's general diet, lipid intake should be maintained at an adequate level (30%). This is particularly important for females specializing in long-duration events. With protein balance, it has been shown that a negative nitrogen balance is more often observed in female athletes than in male athletes. It is therefore especially important to ensure that this remains the case during periods of caloric restriction, especially when working with female athletes showing a tendency to limit their caloric intake on a daily basis. In the post-exercise period, females display lower thermolytic capacities than males. Therefore, the use of cooling recovery methods following exercise, such as cold water immersion or the use of a cooling vest, appear particularly beneficial for female athletes. In addition, a greater decrease in arterial blood pressure is observed after exercise in females than in males. Given that the return to homeostasis after a brief intense exercise appears linked to maintaining good venous return, it is conceivable that female athletes would find a greater advantage to active recovery modes than males. This article reviews some of the major gender differences in the metabolic, inflammatory and thermoregulatory response to exercise and its subsequent recovery. Particular attention is given to the identification of which recovery strategies may be the most pertinent to the design of training programmes for athletic females, in order to optimize the physiological adaptations sought for improving performance and maintaining health.     

Heat illness in athletes: the dangerous combination of heat, humidity and exercise

In 1980, 1700 people died during a prolonged heat wave in a region under-prepared for heat illness prevention. Dramatically underreported, heat-related pathology contributes to significant morbidity as well as occasional mortality in athletic, elderly, paediatric and disabled populations. Among US high school athletes, heat illness is the third leading cause of death. Significant risk factors for heat illness include dehydration, hot and humid climate, obesity, low physical fitness, lack of acclimatisation, previous history of heat stroke, sleep deprivation, medications (especially diuretics or antidepressants), sweat gland dysfunction, and upper respiratory or gastrointestinal illness. Many of these risk factors can be addressed with education and awareness of patients at risk. Dehydration, with fluid loss occasionally as high as 6-10% of bodyweight, appears to be one of the most common risk factors for heat illness in patients exercising in the heat. Core body temperature has been shown to rise an additional 0.15-0.2 degrees C for every 1% of bodyweight lost to dehydration during exercise.Identifying athletes at risk, limiting environmental exposure, and monitoring closely for signs and symptoms are all important components of preventing heat illness. However, monitoring hydration status and early intervention may be the most important factors in preventing severe heat illness.     

Cardiovascular responses to heat acclimatisation in athletes with spinal cord injury

ObjectivesTo determine the effect of heat acclimatisation (HA) training on blood profile and resting cardiac function in elite athletes with spinal cord injury (SCI).DesignQuasi-experimental.MethodsEleven athletes (10 m, 1f) with SCI (C5-T3) completed a five-day isothermic HA protocol whereby gastrointestinal temperature (Tc) was elevated to and maintained at ∼38.5 degrees Celsius (°C) via intermittent exercise for sixty minutes each day. Blood samples were collected pre- and post-HA to determine changes in plasma volume (PV). Doppler ultrasound of the left-ventricular outflow tract and 2-d speckle tracking echocardiography were performed in a subset of athletes (n = 5) to determine changes in indices of resting left-ventricular function and mechanics, respectively.ResultsTen athletes were successfully able to raise and maintain Tc to 38.5 °C. There was a non-significant increase in PV with HA training (ΔPV%: 3.0 ± 5.4%, p = 0.086). Following HA, resting HR decreased (63 ± 4 pre-HA vs. 58 ± 5 bpm post-HA, p = 0.020), velocity time integral (21.4 ± 2.7 vs. 23.7 ± 3.0 cm, p = 0.045) and stroke volume increased (64.8 ± 7.6 vs. 70.2 ± 10.5 mL, p = 0.055).ConclusionsOur findings suggest a short-term HA protocol in athletes with SCI is safe and may induce beneficial changes in indices of resting left-ventricular function — however results are highly individualized. Future studies on HA in athletes with SCI should focus on determining mechanisms of adaptation and performance outcomes.