Measuring Performance during the Menstrual Cycle: A Model Using Oral Contraceptives

Can Neuromuscular Electrical Stimulation Enhance the Effect of Sprint Interval Training?

The aim of this study was to determine the effects of subtetanic neuromuscular electrical stimulation combined with voluntary exercise between repeated Wingate tests on sprint exercise performance and blood lactate accumulation during sprint interval training. Fifteen healthy young males volunteered. After 1-min baseline, participants underwent the Wingate test twice. They performed a 4-min intervention between tests: neuromuscular electrical stimulation with free-weight cycling or voluntary cycling alone [43.6 (8.0) watts], which matched oxygen consumption with neuromuscular electrical stimulation with free-weight cycling. The blood lactate concentration was assessed at the end of the baseline, at 3-min intervention, and on recovery at 1, 3, 5, and 10 min after the second Wingate test. Peak and mean blood lactate concentration during recovery were significantly greater with neuromuscular electrical stimulation with free-weight cycling than voluntary cycling alone (P>0.036 and P=0.011, respectively). Peak power, mean power, and rate of decline (fatigue index) were not significantly different between conditions in both Wingate tests (condition/interaction all P>0.300, partial η2<0.1). Subtetanic neuromuscular electrical stimulation combined with voluntary exercise indicated similar exercise performance and fatigue levels during Wingate tests, but enhanced blood lactate accumulation compared to oxygen consumption-matched voluntary cycling during sprint interval training.

Auditing the representation of hormonal contraceptives in studies assessing exercise performance in women

Hormonal contraceptive (HC) users have a different ovarian hormonal profile compared to eumenorrheic women. Due to the prevalence of HC use amongst sportswomen, there has been increased research efforts to understand their impact on exercise performance. The aim was to audit this research. Studies identified were assessed for HC type, athlete calibre, performance outcome, study design, and quality of methodological control regarding ovarian hormonal profiles. Sixty-eight different HCs were reported across 61 studies. Monophasic combined oral contraceptive (OCP) pills represented 60% of HCs, followed by other pills [34%, phasic-combined, progestogen-only, and un-specified], phasic and long acting reversible contraceptives [5%, vaginal ring, patch, implant, injection, intrauterine system] and unspecified HCs (1%). Eleven percent of participants using HCs were classified as highly trained or elite/international with no participants being classed as world class. Whilst the number of studies involving HCs has increased two-fold over the past decade, the number of studies ranked as gold standard has not increased (HC; 2003-57%, 2011-55%, 2022-43%. OCP; 2003-14%, 2011-17%, 2022-12%). Future research assessing HCs and exercise performance should adopt high-quality research designs and include a broader range of HCs in highly trained to world-class populations to increase the reach and impact of research in this area.

Perspectives on Concurrent Strength and Endurance Training in Healthy Adult Females: A Systematic Review

BACKGROUND

Both strength and endurance training are included in global exercise recommendations and are the main components of training programs for competitive sports. While an abundance of research has been published regarding concurrent strength and endurance training, only a small portion of this research has been conducted in females or has addressed their unique physiological circumstances (e.g., hormonal profiles related to menstrual cycle phase, menstrual dysfunction, and hormonal contraceptive use), which may influence training responses and adaptations.

OBJECTIVE

The aim was to complete a systematic review of the scientific literature regarding training adaptations following concurrent strength and endurance training in apparently healthy adult females.

METHODS

A systematic electronic search for articles was performed in July 2021 and again in December 2022 using PubMed and Medline. This review followed, where applicable, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The quality of the included studies was assessed using a modified Downs and Black checklist. Inclusion criteria were (1) fully published peer-reviewed publications; (2) study published in English; (3) participants were healthy normal weight or overweight females of reproductive age (mean age between > 18 and < 50) or presented as a group (n > 5) in studies including both females and males and where female results were reported separately; (4) participants were randomly assigned to intervention groups, when warranted, and the study included measures of maximal strength and endurance performance; and (5) the duration of the intervention was ≥ 8 weeks to ensure a meaningful training duration.

RESULTS

Fourteen studies met the inclusion criteria (seven combined strength training with running, four with cycling, and three with rowing or cross-country skiing). These studies indicated that concurrent strength and endurance training generally increases parameters associated with strength and endurance performance in female participants, while several other health benefits such as, e.g., improved body composition and blood lipid profile were reported in individual studies. The presence of an "interference effect" in females could not be assessed from the included studies as this was not the focus of any included research and single-mode training groups were not always included alongside concurrent training groups. Importantly, the influence of concurrent training on fast-force production was limited, while the unique circumstances affecting females were not considered/reported in most studies. Overall study quality was low to moderate.

CONCLUSION

Concurrent strength and endurance training appears to be beneficial in increasing strength and endurance capacity in females; however, multiple research paradigms must be explored to better understand the influence of concurrent training modalities in females. Future research should explore the influence of concurrent strength and endurance training on fast-force production, the possible presence of an "interference effect" in athletic populations, and the influence of unique circumstances, such as hormone profile, on training responses and adaptations.

Subtetanic neuromuscular electrical stimulation can maintain Wingate test performance but augment blood lactate accumulation

PURPOSE

Concentration- and time-dependent effect of lactate on physiological adaptation (i.e., glycolytic adaptation and mitochondrial biogenesis) have been reported. Subtetanic neuromuscular electrical stimulation (NMES) with voluntary exercise (VOLES) can increase blood lactate accumulation. However, whether this is also true that VOLES can enhance the blood lactate accumulation during sprint exercise is unknown. Thus, we investigated whether VOLES before the Wingate test can enhance blood lactate accumulation without compromising Wingate exercise performance.

METHODS

Fifteen healthy young males (mean [SD], age: 23 [4] years, body mass index: 22.0 [2.1] kg/m2) volunteered. After resting measurement, participants performed a 3-min intervention: VOLES (NMES with free-weight cycling) or voluntary cycling alone, which matched exercise intensity with VOLES (VOL, 43.6 [8.0] watt). Then, they performed the Wingate test with 30 min free-weight cycling recovery. The blood lactate concentration ([La]b) was assessed at the end of resting and intervention, and recovery at 1, 3, 5, 10, 20, and 30 min.

RESULTS

[La]b during intervention was higher with VOLES than VOL (P = 0.011). The increase in [La]b after the Wingate test was maintained for longer with VOLES than VOL at 10- and 20-min recovery (P = 0.014 and 0.023, respectively). Based on the Wingate test, peak power, mean power, and the rate of decline were not significantly different between VOLES and VOL (P = 0.184, 0.201, and 0.483, respectively).

CONCLUSION

The combination of subtetanic NMES with voluntary exercise before the Wingate test has the potential to enhance blood lactate accumulation. Importantly, this combined approach does not compromise Wingate exercise performance compared to voluntary exercise alone.

Impact of Body Mass Index on Muscle Strength, Thicknesses, and Fiber Composition in Young Women

High body mass index (BMI) may influence muscle strength, muscle thickness (Mtk), and fiber composition. We evaluated these parameters in 31 and 27 women grouped in non-oral contraceptive (non-OC) groups and OC groups, respectively, and further divided them into groups based on BMI: BMI_low, BMI_norm, and BMI_high. Maximum isometric force (F_max), Mtk, and the relative percentage of muscle fiber composition (%) were examined in both groups. F_max and Mtk values were significantly greater in the BMI_high than the BMI_low within the OC group. However, there was no significant difference in the non-OC group. BMI_low and BMI_norm groups showed a difference in the distribution of muscle fiber types 1 and 2 with almost the same proportions in both non-OC and OC groups. However, the BMI_high group showed a difference in the distribution of muscle fiber types 1 and 2, with type 1 about 18.76% higher in the non-OC group. Contrastively, type 2 was about 34.35% higher in the OC group. In this study, we found that there was a significant difference in F_max and Mtk according to the BMI level in the OC group, but no significant difference was found in the non-OC group. Moreover, the distribution of type 2 muscle fibers tended to be higher in the OC group of BMI_high, although the sample size was small. Therefore, although no significant difference of F_max and Mtk was found according to BMI level in the non-OC group in this study, the increase in BMI level appeared to be more associative of muscle strength in the OC group. Based on the present results, future studies are needed that consider the BMI level as well as the presence or absence of OC in future research about women's muscle strength.

The Specificities of Elite Female Athletes: A Multidisciplinary Approach

Female athletes have garnered considerable attention in the last few years as more and more women participate in sports events. However, despite the well-known repercussions of female sex hormones, few studies have investigated the specificities of elite female athletes. In this review, we present the current but still limited data on how normal menstrual phases, altered menstrual phases, and hormonal contraception affect both physical and cognitive performances in these elite athletes. To examine the implicated mechanisms, as well as the potential performances and health risks in this population, we then take a broader multidisciplinary approach and report on the causal/reciprocal relationships between hormonal status and mental and physical health in young (18-40 years) healthy females, both trained and untrained. We thus cover the research on both physiological and psychological variables, as well as on the Athlete Biological Passport used for anti-doping purposes. We consider the fairly frequent discrepancies and summarize the current knowledge in this new field of interest. Last, we conclude with some practical guidelines for eliciting improvements in physical and cognitive performance while minimizing the health risks for female athletes.

The Effect of the Oral Contraceptive Cycle Phase on Exercise-Induced Muscle Damage After Eccentric Exercise in Resistance-Trained Women

ABSTRACT

Romero-Parra, N, Rael, B, Alfaro-Magallanes, VM, Janse de Jonge, X, Cupeiro, R, and Peinado, AB; On Behalf of the IronFEMME Study Group. The effect of the oral contraceptive cycle phase on exercise-induced muscle damage after eccentric exercise in resistance-trained women. J Strength Cond Res 35(2): 353-359, 2021-To evaluate the influence of the active pill phase versus withdrawal phase of a monophasic oral contraceptive (OC) cycle on exercise-induced muscle damage and inflammation after eccentric resistance exercise. Eighteen resistance-trained female OC users (age: 25.6 ± 4.2 years, height: 162.4 ± 5.0 cm, and body mass: 58.1 ± 5.7 kg) performed an eccentric squat-based exercise during the active pill phase and withdrawal phase of their OC cycle. Muscle soreness, counter movement jump (CMJ), and blood markers of muscle damage and inflammation were evaluated before and postexercise (0, 2, 24, and 48 hours). Creatine kinase (CK) values were higher in the withdrawal (181.8 ± 89.8 U·L-1) than in the active pill phase (144.0 ± 39.7 U·L-1) (p < 0.001). The highest CK concentrations and muscle soreness values were observed 24 hours postexercise (217.9 ± 117.5 U·L-1 and 44.7 ± 19.7, respectively) compared with baseline (115.3 ± 37.4 U·L-1 and 4.4 ± 9.2, respectively; p < 0.001). In addition, a decrease in CMJ immediately postexercise (20.23 ± 4.6 cm) was observed in comparison with baseline (24.2 ± 6.1 cm), which was not yet recovered 24 hours postexercise (21.9 ± 5.9 cm; p < 0.001). No other phase or time effects were observed. An eccentric squat-based exercise session elicits muscle damage but no inflammation response in resistance-trained women. Furthermore, the highest CK concentrations observed in the withdrawal phase suggest that this phase might be more vulnerable to muscle damage and, therefore, less adequate to administer high training loads. However, the lack of differences in other muscle damage variables between OC phases does not warrant any guidance on the active pill versus withdrawal phase.

Hormonal Contraceptive Use in Football Codes in Australia

The recent launch of the new National elite women's football competitions in Australia has seen a 20-50% increase in grassroots female participation. With the growing participation across grassroots to elite competitions, understanding the health of female athletes should be prioritized. In elite level athletes, hormonal contraceptive (HC) use is common (~50%), however, little is known about the prevalence and reasons for use and disuse of HC in elite female football athletes. As such, the impact of HC use is often not considered when monitoring the health of female footballers. This study involved a subset of data collected as part of a larger questionnaire investigating menstrual cycle function, hormonal contraception use, and the interaction with training load volume and perceived performance in elite female football code athletes. A total of 177 participants completed the questionnaire across three football codes within Australia (rugby league, rugby union/sevens, Australian football). One third (n = 58) of athletes were currently using HC, predominately in the form of an oral contraceptive pill (OC, n = 47). Reasons for use included: to avoid pregnancy (71%); to control/regulate cycle (38%); and to reduce menstrual pain (36%). However, most athletes using an OC (89%) could not identify the type of pill used (e.g., mono-, bi-, or triphasic). The main reason for disuse was due to the negative side effects (n = 23), such as mood swings, weight gain, and depression/anxiety. Comparing HC users and non-users, there were no statistical differences in the number of reported menstrual symptoms, use of medication to relieve menstrual pain, or frequency for needing to adapt training due to their menstrual cycle (p > 0.05). Since most athletes were unaware of the type of OC they used, female football athletes require further education about the different types of HC, and specifically OC, available to them. Similarities in the symptoms experienced, pain management, and training adaptation requirements between groups suggests that HC use may not have the intended outcome for certain athletes. As such, greater awareness of athlete's personal experiences with the menstrual cycle, how HC may influence their experience, and acknowledgment of non-pharmacological methods to help manage menstrual cycle related symptoms are warranted.

Effect of administration of monophasic oral contraceptive on the body composition and aerobic and anaerobic capacities of female athletes

AIM

To examine the effects of administration of monophasic oral contraceptive (OC) on the body composition and aerobic and anaerobic capacities of female athletes.

METHODS

Ten female athletes (23.0 ± 4.1 years old) participated in this study. All the subjects were examined during the menstrual cycle (early follicular [EF], middle luteal [ML]) and OC cycle (inactive OC, and active OC phases). After the menstrual cycle measurements, all the subjects began taking OC. The athletes tested using a body composition, circumferences, the lactate curve test, the maximal oxygen consumption test, and the Wingate test during all phases.

RESULTS

Waist circumference was lower during the OC cycle than menstrual cycle (P < 0.05), and the other circumferences of parts were not different during the menstrual or OC cycles. However, there were no differences in body composition before and after taking OC. The phase of the menstrual or OC cycle did not affect maximal oxygen consumption, heart rate max or power output at a blood lactate concentration of 2 and 4 mmol/L between the menstrual and OC cycle phases. Although, the peak blood lactate level after the Wingate test was higher during the OC cycle (inactive OC phase, 13.0 ± 2.4 mmol/L; active OC phase, 12.4 ± 3.0 mmol/L) than during the menstrual cycle (EF phase, 11.9 ± 2.1 mmol/L; ML phase, 11.4 ± 2.1 mmol/L; P < 0.05), the peak and average power in the Wingate test did not change during the menstrual and OC cycle phases.

CONCLUSION

Administration of monophasic OC did not affect the body composition or aerobic and anaerobic capacities of female athletes.

The Effects of Oral Contraceptives on Exercise Performance in Women: A Systematic Review and Meta-analysis

BACKGROUND

Oral contraceptive pills (OCPs) are double agents, which downregulate endogenous concentrations of oestradiol and progesterone whilst simultaneously providing daily supplementation of exogenous oestrogen and progestin during the OCP-taking days. This altered hormonal milieu differs significantly from that of eumenorrheic women and might impact exercise performance, due to changes in ovarian hormone-mediated physiological processes.

OBJECTIVE

To explore the effects of OCPs on exercise performance in women and to provide evidence-based performance recommendations to users.

METHODS

This review complied with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A between-group analysis was performed, wherein performance of OCP users was compared with naturally menstruating women, and a within-group analysis was conducted, wherein performance during OCP consumption was compared with OCP withdrawal. For the between-group analysis, women were phase matched in two ways: (1) OCP withdrawal versus the early follicular phase of the menstrual cycle and (2) OCP consumption versus all phases of the menstrual cycle except for the early follicular phase. Study quality was assessed using a modified Downs and Black Checklist and a strategy based on the recommendations of the Grading of Recommendations Assessment Development and Evaluation working group. All meta-analyses were conducted within a Bayesian framework to facilitate probabilistic interpretations.

RESULTS

42 studies and 590 participants were included. Most studies (83%) were graded as moderate, low or very low quality, with 17% achieving high quality. For the between-group meta-analysis comparing OCP users with naturally menstruating women, posterior estimates of the pooled effect were used to calculate the probability of at least a small effect (d ≥ 0.2). Across the two between-group comparison methods, the probability of a small effect on performance favouring habitual OCP users was effectually zero (p < 0.001). In contrast, the probability of a small effect on performance favouring naturally menstruating women was moderate under comparison method (1) (d ≥ 0.2; p = 0.40) and small under comparison method (2) (d ≥ 0.2; p = 0.19). Relatively large between-study variance was identified for both between-group comparisons ([Formula: see text]0.5 = 0.16 [95% credible interval (CrI) 0.01-0.44] and [Formula: see text]0.5 = 0.22 [95% CrI 0.06-0.45]). For the within-group analysis comparing OCP consumption with withdrawal, posterior estimates of the pooled effect size identified almost zero probability of a small effect on performance in either direction (d ≥ 0.2; p ≤ 0.001).

CONCLUSIONS

OCP use might result in slightly inferior exercise performance on average when compared to naturally menstruating women, although any group-level effect is most likely to be trivial. Practically, as effects tended to be trivial and variable across studies, the current evidence does not warrant general guidance on OCP use compared with non-use. Therefore, when exercise performance is a priority, an individualised approach might be more appropriate. The analysis also indicated that exercise performance was consistent across the OCP cycle.

Repeated Menthol Mouth Swilling Affects Neither Strength nor Power Performance

This study aimed to assess the effects of repeated menthol mouth swilling upon strength and power performance. Nineteen (10 male) participants completed familiarisation and experimental trials of repeated menthol mouth swilling (0.1% concentration) or control (no swill) in a randomised crossover design. Participants performed an isometric mid-thigh pull (IMTP; peak and mean force; N), vertical jump (peak; cm) and six second sprint (peak and mean power; W) under each condition. Participants completed three efforts per exercise task interspersed with three-minute recoveries. Mean best values were analysed via a two-way mixed repeated measures ANOVA, and differences reported as effect sizes ± 95% confidence intervals, with accompanying descriptors and p values. Differences in peak IMTP values were unclear between familiarisation and experimental trials, and between menthol and control conditions. Mean IMTP force differed between familiarisation and control (0.51; -0.15 to 1.14; p = 0.001) and familiarisation and menthol conditions (0.50; -0.15 to 1.14; p = 0.002) by a small degree, but were unclear between control and menthol conditions. Unclear differences were also noted on vertical jump performance compared to familiarisation and between experimental conditions, with repeated six second peak and average power performance also showing unclear effects across all comparisons. We conclude that repeated menthol mouth swilling does not improve strength or power performance.

Assessment of Musculoskeletal Strength and Levels of Fatigue during Different Phases of Menstrual Cycle in Young Adults

INTRODUCTION

Some of the physiological factors and athletic performance might show variation along the phases of menstrual cycle. The alterations seen in these physiological parameters of various systems relating to oscillations in hormonal levels do affect the autonomic nervous system and metabolic functions. Former studies heave inconclusively about the influence of hormones on exercise performance, predominantly muscle strength and rate of fatigue during different phases of the menstrual cycle. Studies regarding influence of these variations during bleeding phase were not done.

AIM

To evaluate the muscle strength variations and also the rate of fatigue during various phases of the menstrual cycle in young adults.

MATERIALS AND METHODS

This was a prospective study conducted among 100 healthy adult female volunteers aged 18-24 years, with normal regular menstrual cycles persistent between 26- 32 days (average of 28 days), for a minimum of last 6 months. Muscle strength was assessed by calculating the work done and fatigue rate using Mosso's ergograph and by handgrip dynamometer strength. Each subject was evaluated consecutively for two menstrual cycles in all three phases which were classified as Phase 1- Menstrual phase, Phase 2- Follicular phase and Phase 3- Luteal phase. The data obtained was analysed by statistical tool One-way ANOVA followed by a post-hoc Tukeys test. A p-value of ≤ 0.05 was considered significant.

RESULTS

The amount of work done and handgrip strength was significantly higher in phase 2 (p<0.001) and relatively reduced in phase 1 and 3 (p<0.001) of menstrual cycle. In terms of fatigue rate percentage, phase 2 showed significantly lesser values (p<0.001) as compared to phase 1 and 3 of menstrual cycle.

CONCLUSION

We conclude that the cyclical variation in endogenous reproductive hormones increases the muscle strength in follicular phase of the menstrual cycle. Thus provide support for the influence of these hormones in regulation of these parameters in the premenopausal age group.

Oxidative Stress in Female Athletes Using Combined Oral Contraceptives

Background

Oxidative stress in female athletes is understudied. We investigated oxidative stress in sportswomen of different disciplines according to combined oral contraceptive (OC) use and lifestyle/alimentary habits.

Methods

Italian sportswomen (n = 144; mean age 23.4 ± 4.2 years; body mass index 21.2 ± 2.2 kg m⁻²; sport activity 9.2 ± 4.1 h week⁻¹) were analyzed; 48 % were volleyball players, 12.5 % soccer players, 10.4 % track-and-field sports, and followed by other disciplines’ athletes. Oxidative stress was evaluated by free oxygen radical test (FORT) assessing blood hydroperoxides and free oxygen radical defense (FORD) assay evaluating antioxidant capacity in OC users (n = 42) compared to non-OC users.

Results

Elevated oxidative stress levels (≥310 FORT units) were found in 92.9 % of OC users and in 23.5 % of non-OC users (crude OR = 42, 95 % CI 12–149, p < 0.001; adjusted OR = 60, 95 % CI 11–322, p < 0.001). Continuous values of hydroperoxides were twofold higher in OC users versus non-OC users (median 484 versus 270 FORT units, p < 0.001) and were inversely related to FORD units in OC users (p = 0.01). Hydroperoxides were not associated with weekly hours of exercise. In OC users, lifestyle/alimentary habits were not correlated to hydroperoxides. In non-OC users only, hydroperoxide values were positively correlated with weight and BMI and inversely correlated with chocolate and fish consumption.

Conclusions

The markedly elevated oxidative stress we revealed in OC-user athletes could be detrimental to physical activity and elevate cardiovascular risk (as thromboembolism). Further research is needed to extend our results, to clarify the biochemical pathways leading to increased hydroperoxides (mainly lipid peroxides) and reduced antioxidant defense, and to elucidate the potential effects on athletic performance. OC use should be considered when developing gender-focused strategies against oxidative stress.

The effect of ice ingestion on female athletes performing intermittent exercise in hot conditions

Studies have reported the benefits of pre-cooling prior to exercise in the heat for male athletes, but at this time no research has investigated female athletes. The aim of the following study was to test the effects of pre-cooling on female repeat sprint performance in hot, humid conditions; namely is ice ingestion effective in reducing core temperature (Tc) and does this reduced Tc lead to improved repeat sprint performance in female athletes? Nine female team sport athletes with mean age (21.0 ± 1.2 y), height (169.8 ± 4.1 cm) and body mass (62.3 ± 5.0 kg) participated in this study. Participants completed 72 min of an intermittent sprint protocol (ISP) consisting of 2 × 36 min halves in hot, humid conditions (33.1 ± 0.1 °C, 60.3 ± 1.5% RH) on a cycle ergometer. This was preceded by 30 min of either ice ingestion (ICE) or water consumption (CON) in a randomised order. At the end of the pre-cooling period, Tc significantly decreased following ICE (-0.7 ± 0.3 °C) compared to CON (-0.1 ± 0.2 °C; p = 0.001). Tc also remained lower in ICE compared to CON during the ISP (p = 0.001). Ratings of perceived thermal sensation were lower in ICE compared to CON (p = 0.032) at the beginning (p = 0.022) and mid-point (p = 0.035) of the second half. No differences in work, mean power, peak power, rating of perceived exertion, heart rate or sweat loss between conditions were recorded (p > 0.05). Ice ingestion significantly reduced female Tc prior to intermittent exercise in the heat and reduced thermal sensation; however, this did not coincide with improved performance.

Oral contraceptives do not affect muscle strength and hop performance in active women

OBJECTIVE

The primary aim of this study was to compare muscle strength in the upper and lower limb, as well as hop performance during oral contraceptive (OC) use with non-OC use in the same woman. A secondary aim was to compare muscle strength and hop performance within 3 specific phases of an OC cycle, as well as during a menstrual cycle of the corresponding cycle days (non-OC cycle).

DESIGN

Crossover.

SETTING

Research laboratory.

PARTICIPANTS

Seventeen moderate to highly recreationally active women participated in the study.

INTERVENTION

Observational study with no intervention.

MAIN OUTCOME MEASURES

Maximal isokinetic muscle strength of knee extensors, isometric handgrip strength, and 1-leg hop test for distance were measured during 1 OC cycle and 1 non-OC cycle at 3 specific phases, respectively, using a crossover design.

RESULTS

No significant differences were found in terms of muscle strength and hop performance between the OC cycle and the non-OC cycle. Furthermore, no significant difference in muscle strength and hop performance could be demonstrated within the OC cycle or within the phases of the menstrual cycle except from maximal isokinetic muscle strength in the knee extensors detected between the early follicular phase and the luteal phase.

CONCLUSIONS

We found no support for any significant influence of OC use on muscle strength and hop performance in healthy moderately active women.

Oral contraceptive cycle phase does not affect 200-m swim time trial performance

The purpose of this study was to examine whether swimming performance was affected by acute hormonal fluctuation within a monophasic oral contraceptive (OC) cycle. Six competitive swimmers and water polo players completed a 200-m time trial at 3 time points of a single OC cycle: during the consumption phase (CONS), early (WITH1), and late in the withdrawal phase (WITH2). Split times and stroke rate were recorded during the time trial, and heart rate, blood lactate, glucose, and pH were measured after each performance test. Resting endogenous serum estradiol and progesterone concentrations were also assessed. No significant differences were observed between phases for body composition, 200-m swim time, mean stroke rate, peak heart rate, or blood glucose (p > 0.05). The mean peak blood lactate was significantly lower during WITH2 (9.9 ± 3.0 mmol·L(-1)) compared with that of CONS (12.5 ± 3.0 mmol·L(-1)) and mean pH higher during WITH2 (7.183 ± 0.111) compared with that of CONS (7.144 ± 0.092). Serum estradiol levels were significantly greater during WITH2 compared with that during WITH1 and CONS, but there was no difference in serum progesterone levels. These results demonstrate that for monophasic OC users, cycle phase does not impact the 200-m swimming performance. There was a reduction in blood lactate and an increase in pH during the withdrawal phase, possibly because of an increase in fluid retention, plasma volume, and cellular alkalosis. Therefore, female 200-m swimmers taking a monophasic OC need not be concerned by the phase of their cycle with regard to competition and optimizing performance. However, coaches and scientists should exercise caution when interpreting blood lactate results obtained from swimming tests and consider controlling for cycle phase for athletes taking an OC.

Menstrual cycle and oral contraceptives' effects on growth hormone response to sprinting

The present study examined the impact of the menstrual cycle and oral contraceptive (OC) use on the growth hormone response to non-motorized treadmill sprinting. Nine monophasic OC users (21.5 ± 4.7 years old), and 8 normally menstruating women (NM; 21.4 ± 2.9 years old) participated in the study. Each participant completed 2 main trials, each consisting of an all-out 30-s treadmill sprint. The NM group performed one trial in the midfollicular phase (NM follicular) and one in the midluteal phase (NM luteal); the OC group's trials occurred one week into the start of the pill-taking cycle and once during the week in which pills were not taken.Venous blood samples were analyzed for growth hormone, pH, lactate, glucose, and progesterone concentrations. Peak and mean power output did not differ between the groups or with menstrual phase, or between the OC-free and OC trials. Integrated growth hormone was greater in the OC group than in the NM group (p = 0.04) with no phase difference (p = 0.80, mean (SD); NM follicular: 421 (335) and NM luteal: 345 (304) vs. OC free: 737 (471) and OC: 758 (389) µg·L(-1)·90 min(-1)). Blood lactate was higher in the OC group than in the NM group (p = 0.007) and, conversely, pH was lower in the OC group (p = 0.01). These results demonstrate that OC users who take high-androgenicity pills have a higher growth hormone response to sprint running than do normally menstruating women.

Efeito das diferentes fases do ciclo menstrual no desempenho da força muscular em 10RM

O objetivo deste estudo foi verificar o efeito das diferentes fases do ciclo menstrual (CM) no desempenho da força muscular em exercícios resistidos. Participaram do estudo nove mulheres saudáveis, fisicamente ativas, com idade de 27 ± 7 anos, massa corporal 58,2 ± 5kg, estatura 161,1 ± 4,7cm e IMC 20,4 ± 2kg/m². Todas apresentavam CM's regulares (28-31 dias), faziam uso de contraceptivos orais e eram experientes em exercícios resistidos a pelo menos oito meses. Para avaliação da força muscular foi utilizado o teste de 10RM na seguinte ordem: leg press 45º, supino horizontal, cadeira extensora e rosca bíceps. Os testes foram realizados nas três fases do CM: folicular (entre o terceiro e o quinto dia do fluxo menstrual), ovulatória (entre o nono e o 10º dia) e lútea (entre o 17º e o 21º dia). Para a análise estatística foi utilizada a ANOVA de medidas repetidas, os dados analisados no software SPSS 15.0 e o nível de significância mantido em 5% (p < 0,05). Não foram verificadas diferenças estatisticamente significativas nas cargas mobilizadas entre os diferentes períodos do CM em nenhum dos quatro exercícios avaliados. No exercício leg press foi verificado um incremento de 5% na força muscular na fase lútea. Nas demais fases e exercícios essas diferenças não foram observadas. Podese concluir que as fases do CM não influenciam o desempenho da força muscular nos exercícios resistidos, sejam eles uni ou multiarticulares, para grandes ou pequenos grupamentos musculares ou em diferentes segmentos corporais

Effect of menstrual cycle phase on sprinting performance

This study examined the effects of menstrual cycle phase (MCP) upon sprinting and recovery as well as upon metabolic responses to such exercise. Eight females performed a repeated 30-s sprint on a non-motorised treadmill interspersed with a 2-min rest in three phases of the MCP, follicular (low 17beta-estradiol and progesterone), just prior to ovulation (midcycle trial, highest 17beta-estradiol concentration and low progesterone) and in the luteal phase (high 17beta-estradiol and high progesterone). MCP was verified later by radioimmunoassay of 17beta-estradiol and progesterone. Peak power output (PPO) and mean power output (MPO) were unaltered (P > 0.05) due to MCP [PPO for sprint 1: 463 (18) W vs. 443 (15) W vs. 449 (18) W; PPO for sprint 2: 395 (17) W vs. 359 (16) W vs. 397 (17) W; MPO for sprint 1: 302 (15) W vs. 298 (13) W vs. 298 (14) W; MPO for sprint 2: 252 (10) W vs. 248 (10) W vs. 259 (12) W for follicular, midcycle and luteal trial, mean (SEM), respectively]. Similarly, percentage recovery of PPO and MPO (the PPO or MPO during sprint 2 expressed as a percentage of the PPO or MPO during sprint 1) was also unchanged (P > 0.05). Blood lactate, blood pH and plasma ammonia after sprinting and estimated plasma volume were also unaltered by MCP (P > 0.05). These findings suggest that hormonal fluctuations due to MCP do not interfere with maximal intensity whole body sprinting and the metabolic responses to such exercise.

Athletic performance and the oral contraceptive

Some reports suggest variation in physiological responses and athletic performance, for female athletes at specific phases of the menstrual cycle. However, inconsistent findings are common due to the inappropriate verification of menstrual cycle phase, small subject numbers, high intra- and interindividual variability in estrogen and progesterone concentration, and the pulsatile secretion of these hormones. Therefore, the oral contraceptive (OC) cycle may provide a more stable environment in which to evaluate the acute effect of reproductive hormones on physiological variables and exercise performance. To date, most of the OC research has compared differences between OC use and nonuse, and few researchers have examined within-cycle effects of the OC. It is also apparent that OC use is becoming far more prevalent in athletes; hence the effect of the different exogenous and endogenous hormonal profiles on athletic performance should be investigated. Research to date identifies potential for variation in aerobic performance, anaerobic capacity, anaerobic power and reactive strength throughout an OC cycle. The purpose of this review is to present and evaluate the current literature on the physiology of exercise and athletic performance during the OC cycle.

Endogenous and exogenous female sex hormones and renal electrolyte handling: effects of an acute sodium load on plasma volume at rest

This study was conducted to investigate effects of an acute sodium load on resting plasma volume (PV) and renal mechanisms across the menstrual cycle of endurance-trained women with natural (NAT) or oral contraceptive pill (OCP) controlled cycles. Twelve women were assigned to one of two groups, according to their usage status: 1) OCP [ n = 6, 29 yr (SD 6), 59.4 kg (SD 3.2)], or 2) NAT [ n = 6, 24 yr (SD 5), 61.3 kg (SD 3.6)]. The sodium load was administered as a concentrated sodium chloride/citrate beverage (164 mmol Na+/l, 253 mosmol/kgH2O, 10 ml/kg body mass) during the last high-hormone week of the OCP cycle (OCPhigh) or late luteal phase of the NAT cycle (NAThigh) and during the low-hormone sugar pill week of OCP (OCPlow) or early follicular phase of the NAT cycle (NATlow). The beverage (∼628 ml) was ingested in seven portions across 60 min. Over the next 4 h, PV expanded more in the low-hormone phase for both groups (time-averaged change): OCPlow 6.1% (SD 1.1) and NATlow 5.4% (SD 1.2) vs. OCPhigh 3.9% (SD 0.9) and NAThigh 3.5% (SD 0.8) ( P = 0.02). The arginine vasopressin increased less in the low-hormone phase [1.63 (SD 0.2) and 1.30 pg/ml (SD 0.2) vs. 1.82 (SD 0.3) and 1.57 pg/ml (SD 0.5), P = 0.0001], as did plasma aldosterone concentration (∼64% lower, P = 0.0001). Thus PV increased more and renal hormone sensitivity was decreased in the low-hormone menstrual phase following sodium/fluid ingestion, irrespective of OCP usage.

The influence of oral contraceptives on athletic performance in female athletes

It is now estimated that the prevalence of oral contraceptive use in athletic women matches that of women in the general population. The oral contraceptive pill (OCP) reduces cycle-length variability and provides a consistent 28-day cycle by controlling concentrations of endogenous sex hormones. The OCP is administered in three different forms that differ widely in chemical constitution and concomitant effects on the human body. As fluctuation in sex steroids are believed to be a possible causal factor in performance and exercise capacity, it is imperative to understand the effect of administering the various types of OCP on women. However, the research into oral contraceptives and exercise performance is not consistent. The type of OCP administered (monophasic, biphasic or triphasic), as well as the type and dose of estrogen and progestogen within, will have varying effects on exercise. To date, research in the area of oral contraceptives and exercise capacity is sparse and much has been plagued by poor research design, methodology and small sample size. It is clear from the research to date that more randomised clinical trials are urgently required to assess the array of OCP formulations currently available to women and their concomitant effect on health and exercise capacity. Therefore, the purpose of this article is to critically appraise the literature to date and to provide a current review of the physiological scientific knowledge base in relation to the OCP and exercise performance. In addition, methodological control, design and conduct will be considered with future areas of research highlighted.

Preexercise sodium loading aids fluid balance and endurance for women exercising in the heat

This study was conducted during the high-hormone phase of both natural and oral contraceptive pill (OCP)-mediated menstrual cycles to determine whether preexercise ingestion of a concentrated sodium beverage would increase plasma volume (PV), reduce physiological strain, and aid endurance of moderately trained women cycling in warm conditions. Thirteen trained cyclists [peak O2 uptake 52 ml·kg−1·min−1 (SD 2), age 26 yr (SD 6), weight 60.8 kg (SD 5)] who were oral contraceptive users ( n = 6) or not ( n = 7) completed this double-blind, crossover experiment. Cyclists ingested a concentrated-sodium (High Na+: 164 mmol Na+/l) or low-sodium (Low Na+: 10 mmol Na+/l) beverage (10 ml/kg) before cycling to exhaustion at 70% Peak O2 uptake in warm conditions (32°C, 50% relative humidity, air velocity 4.5 m/s). Beverage (∼628 ml) was ingested in seven portions across 60 min beginning 105 min before exercise, with no additional fluid given until the end of the trial. Trials were separated by one to two menstrual cycles. High Na+ increased PV (calculated from hematocrit and hemoglobin concentration) before exercise, whereas Low Na+ did not [−4.4 (SD 1.1) vs. −1.9% (SD 1.3); 95% confidence interval: for the difference 5.20, 6.92; P < 0.0001], and it involved greater time to exhaustion [98.8 (SD 25.6) vs. 78.7 (SD 24.6) min; 95% confidence interval: 13.3, 26.8; P < 0.0001]. Core temperature rose more quickly with Low Na+ [1.6°C/h (SD 0.2)] than High Na+ [1.2°C/h (SD 0.2); P = 0.04]. Plasma [AVP], [Na+] concentration, and osmolality, and urine volume, [Na+], and osmolality decreased with sodium loading ( P < 0.05) independent of pill usage. Thus preexercise ingestion of a concentrated sodium beverage increased PV, reduced thermoregulatory strain, and increased exercise capacity for women in the high-hormone phase of natural and oral contraceptive pill-mediated menstrual cycles, in warm conditions.

Effects of the menstrual cycle on anterior cruciate ligament injury risk: a systematic review

Several theories have been proposed to explain the 3- to 6-fold gender difference in the incidence of anterior cruciate ligament injuries. One potential theory for the increased incidence is based on gender-related hormonal differences between men and women, especially after puberty and the onset of menses in the female athlete. The purpose of this systematic review was to compile and systematically analyze the published literature to determine if the menstrual cycle is associated with anterior cruciate ligament injury risk and to provide an objective comparison of the published results. Investigations were included in the systematic review if the report included associations between the menstrual cycle and noncontact anterior cruciate ligament injuries in female athletes. Abstracts and unpublished studies were excluded. Seven articles were identified that met the systematic review inclusion criteria. The 7 reviewed studies favored an effect of the first half, or preovulatory phase, of the menstrual cycle for increased anterior cruciate ligament injuries. The 6 studies that separated the non-oral contraceptive and oral contraceptive data also favored an effect of the first half of the menstrual cycle for increased anterior cruciate ligament injuries. The clinical relevance of this finding is that female athletes may be more predisposed to anterior cruciate ligament injuries during the preovulatory phase of the menstrual cycle. These findings may lead to potential interventions targeted toward this phase of the menstrual cycle to reduce the incidence of anterior cruciate ligament injury.

Androgenicity of the progestin in oral contraceptives does not affect maximal leg strength

PURPOSE

This study was conducted to examine androgenicity of the progestin in oral contraceptive pills and its effect on maximal leg strength in females.

METHODS

Twelve participants who were using a monophasic pill containing 30 microg ethinylestradiol plus either 150 microg levonorgestrel (LEV) or 250 microg norgestimate (NOR) for at least the last 6 months were recruited (mean+/-SEM; LEV: age, 19.8+/-0.3 years; stature, 1.67+/-0.17 m; mass, 65.9+/-1.9 kg; NOR: age, 20.6+/-0.2 years; stature, 1.65+/-0.17 m; mass, 64.6+/-2.4 kg). Three maximal isokinetic extension and flexion tests were performed on three occasions (Days 3-6, 11-14 and 18-21 of the pill cycle) to assess peak extension and peak flexion torque (in Newton meters).

RESULTS

No significant (p>.05) differences were found in the LEV and NOR groups in peak extension torque (F=0.719; p=.416) or peak flexion torque (F=0.291, p=.601) throughout the pill cycle and between groups.

CONCLUSION

In this small study, the androgenicity of the progestin in the contraceptive pill had no significant association with maximal strength in these female athletes.

The menstrual cycle and sport performance

The female sex steroid hormones estrogen and progesterone have potential effects on exercise capacity and performance through numerous mechanisms, such as substrate metabolism, cardiorespiratory function, thermoregulation, psychologic factors, and injuries. Consequently, hormone level changes may theoretically lead to either improved or decreased performance at various times throughout the menstrual cycle. Numerous methodological issues and a paucity of studies have precluded evidence-based conclusions in almost every area of research in this field. In addition, there appears to be a great degree of inter- and intraindividual variability in these hormonal responses. Using oral contraceptives may be advantageous for female athletes who are negatively affected by their menstrual cycle, as they may provide a stable yet controllable hormonal milieu for training and competition.

Effects of menstrual phase on performance and recovery in intense intermittent activity

Game sport and training require repeated high intensity bursts. This study examined differences between high intensity, intermittent work in two phases of the menstrual cycle. Six physically active young women (age 19-29) performed 10 6-s sprints on a cycle ergometer in both the mid-follicular (FP) (days 6-10) and late-luteal phases (LP) (days 20-24) of the menstrual cycle. Work, power, oxygen intake (VO2) parameters, and capillarized blood lactate were measured. Data are analyzed using the Friedman and Wilcoxon matched pairs tests. There was no difference between menstrual phases in peak 6-s power (6.8(0.6) W kg(-1) in FP, 6.9(0.6) W kg(-1) in LP), the drop off in work (1.2(3.5) J kg(-1) in FP and 1.0(2.7) J kg(-1) in LP), or in the sprint VO2 (23.7(1.5) mL kg(-1) min(-1) in LP and 24.3(2.4) mL kg(-1) min(-1) in FP). Capillarized blood lactate was also similar in both phases of the menstrual cycle both at 1 min (9.2(2.7) mmol L(-1) in FP, 9.2(3.1) mmol L(-1)) and at 3 min (9.0(2.2) mmol L(-1) in FP, 9.2(2.2) mmol L(-1) in LP). However, the average 6-s work was greater in the LP (39.3(3.4) J kg(-1)) than during the FP (38.3(3.1) J kg(-1)) (P=0.023). The recovery VO2 was also greater in the LP than the FP (26.3(2.4) mL kg(-1) min(-1) in LP, 25.0(2.6) mL kg(-1) min(-1) in FP, P=0.023). Average work over a series of sprints and the VO2 consumed between sprints may be slightly greater during the LP than the FP of the menstrual cycle.