Effect of different phases of menstrual cycle in heart rate variability of physically active women

Examining the acute cardiovagal consequences of supine recovery during high-intensity interval exercise

PURPOSE

Exercise training requires the careful application of training dose to maximize adaptation while minimizing the risk of illness and injury. High-intensity interval training (HIIT) is a potent method for improving health and fitness but generates substantial autonomic imbalance. Assuming a supine posture between intervals is a novel strategy that could enhance physiological readiness and training adaptations. This study aimed to establish the safety and feasibility of supine recovery within a HIIT session and explore its acute effects.

METHODS

Fifteen healthy, active males (18-34 years) underwent assessment of cardiopulmonary fitness. Participants completed two identical HIIT treadmill sessions (4 x [3 min at 95% VO2max, 3 min recovery]) employing passive recovery in standing (STANDard) or supine (SUPER) posture between intervals. Heart rate variability (HRV), HRV recovery (HRVrec; lnRMSSD) and heart rate recovery at 1 min (HRrec) were assessed using submaximal constant speed running tests (CST) completed prior to, immediately after and 24 h following HIIT.

RESULTS

No severe adverse events occurred with SUPER, and compliance was similar between conditions (100 ± 0%). The change in HRVrec from the CST pre-to-post-HIIT was not different between conditions (p = 0.38); however, HRrec was faster following SUPER (39 ± 7 bpm) vs. STANDard (36 ± 5 bpm). HRV 24 h post-SUPER was also greater (3.56 ± 0.57 ms) compared to STANDard (3.37 ± 0.42 ms). Despite no differences in perceived exertion (p = 0.23) and blood lactate levels (p = 0.35) between SUPER and STANDard, average running HRs were lower (p = 0.04) with SUPER (174 ± 7 bpm) vs. STANDard (176 ± 7 bpm).

CONCLUSIONS

Supine recovery within HIIT attenuates acute cardioautonomic perturbation and accelerates post-exercise vagal reactivation. SUPER enhances recovery of vagal modulation, potentially improving physiological preparedness 24 h post-HIIT. Further research exploring the chronic effects of SUPER are now warranted.

Physiological, anthropometric and athletic performance adaptations from completing a 1-month pre-season period. A two-year longitudinal study in female collegiate soccer players

Introduction

Collegiate coaches and integrative support staff often utilize pre-season as a brief and intense training period to prepare athletes technically, tactically, and physiologically, to meet the demands of competition during a soccer season. This study sought to examine the dose-response from performing on-field soccer activities during a four-week pre-season period in female collegiate soccer players, and if the magnitude in response was associated with accumulated exercise stress.

Methods

A total of twenty-seven healthy female soccer players training as part of a collegiate soccer program volunteered to participate in this two-year longitudinal study. Data collection commenced prior to the start of each pre-season period, at the beginning of August, and was completed at the beginning of September, when pre-season ended. Data collection periods were separated by a 31-day period. Indices of cardiovascular function, anthropometry, and athletic performance were examined during each data collection period. Internal and external measures of accumulated exercise stress were recorded using the Polar Team Pro® system.

Results

When comparing the beginning to the end of pre-season, significant improvements were observed in body fat (%) [24.2 ± 6.0 "vs." 23.3 ± 5.6, p = 0.001], heart rate variability (rMSSD) [51.8 ± 25.1 "vs." 67.9 ± 34.6 ms, p = 0.002], resting heart (bpm) [73.8 ± 12.1 "vs." 64.3 ± 8.8, p = 0.001] and cardiorespiratory performance (YoYo IRTL-1) [925.8 ± 272.8 "vs." 1,062.6 ± 223.3 m, p = 0.001]. Significant reductions in musculoskeletal performance were observed through vertical jump height (cm) [24.9 ± 23.7, p = 0.04]. Change in the end of pre-season body weight (kg) was significantly associated with accumulated accelerations and decelerations [r ≥ 0.49, p = 0.01]. End of pre-season change in cardiorespiratory performance was significantly associated with both accumulated training load (au) and TRIMP (au) [r ≥ 0.63, p = 0.01].

Discussion

In conclusion, performing a four-week pre-season period, involving only on-field training, can promote positive and significant adaptations in anthropometry, cardiovascular function, and athletic performance measures in female collegiate soccer players. The magnitudes of these adaptations were associated with both internal and external measures of accumulated exercise stress.

Menstrual cycle hormones and oral contraceptives: a multimethod systems physiology-based review of their impact on key aspects of female physiology

Hormonal changes around ovulation divide the menstrual cycle (MC) into the follicular and luteal phases. In addition, oral contraceptives (OCs) have active (higher hormone) and placebo phases. Although there are some MC-based effects on various physiological outcomes, we found these differences relatively subtle and difficult to attribute to specific hormones, as estrogen and progesterone fluctuate rather than operating in a complete on/off pattern as observed in cellular or preclinical models often used to substantiate human data. A broad review reveals that the differences between the follicular and luteal phases and between OC active and placebo phases are not associated with marked differences in exercise performance and appear unlikely to influence muscular hypertrophy in response to resistance exercise training. A systematic review and meta-analysis of substrate oxidation between MC phases revealed no difference between phases in the relative carbohydrate and fat oxidation at rest and during acute aerobic exercise. Vascular differences between MC phases are also relatively small or nonexistent. Although OCs can vary in composition and androgenicity, we acknowledge that much more work remains to be done in this area; however, based on what little evidence is currently available, we do not find compelling support for the notion that OC use significantly influences exercise performance, substrate oxidation, or hypertrophy. It is important to note that the study of females requires better methodological control in many areas. Previous studies lacking such rigor have contributed to premature or incorrect conclusions regarding the effects of the MC and systemic hormones on outcomes. While we acknowledge that the evidence in certain research areas is limited, the consensus view is that the impact of the MC and OC use on various aspects of physiology is small or nonexistent.

Heart Rate Variability and Cortisol Levels Before and After a Brief Anaerobic Exercise in Handball Players

ABSTRACT

Kayacan, Y, Makaracı, Y, Ucar, C, Amonette, WE, and Yıldız, S. Heart rate variability and cortisol levels before and after a brief anaerobic exercise in handball players. J Strength Cond Res 37(7): 1479-1485, 2023-Evaluating stress in athletes is important for monitoring overall physiologic load and is a core practice for sport performance teams. This study examined relationships between 2 metrics of training stress, heart rate variability (HRV) and cortisol, before and after intense anaerobic power testing. Electrocardiogram recordings and saliva samples were collected before and immediately after a Wingate anaerobic power test (WAnT-30) from professional handball players ( n = 20) and sedentary controls ( n = 18). Between-group differences and correlations were computed to assess study hypotheses. No differences were observed in HRV frequency-dependent parameters between groups, but in athletes, Min. R-R ( p < 0.01) and Avg.R-R ( p = 0.03) before WAnT-30 and the percentage of successive normal cardiac beat intervals greater than 50 milliseconds (i.e., pNN50; p = 0.03) after WAnT-30 were elevated. A high positive correlation was detected between the pretest and post-test cortisol levels in athletes ( p = 0.0001; r = 0.87) but not in sedentary individuals. No correlations were observed between the cortisol levels and WAnT-30 power parameters in either group. Relationships were evident in the standard deviation of RR intervals ( p = 0.02, r = -0.53), square root of the mean squared difference of successive RR intervals ( p = 0.043, r = -0.46), very low frequency ( p = 0.032; r = -0.480), high-frequency ( p = 0.02; r = -0.52) variables, and pretesting cortisol in athletes. These findings suggest that HRV analysis is a valuable tool for examining cardiovascular regulation, independent of cortisol; the data may provide valuable information for performance teams in evaluating acute stress.

Nocturnal Heart Rate Variability in Women Discordant for Hormonal Contraceptive Use

PURPOSE

The aim of this study was to investigate within-cycle differences in nocturnal heart rate (HR) and heart rate variability (HRV) in naturally menstruating women (NM) and women using combined hormonal contraceptives (CU) or progestin-only hormonal contraceptives (PU).

METHODS

Physically active participants were recruited into three groups: NM ( n = 19), CU ( n = 11), and PU ( n = 12). Participants' HR and HRV (with Bodyguard 2 HRV monitor) and blood hormones were monitored during one menstrual cycle (MC) (NM group) or for 4 wk (CU and PU groups). Estradiol, progesterone, and luteinizing hormone were analyzed from fasting blood samples collected four times in the NM (M1 = bleeding, M2 = follicular phase, M3 = ovulation, and M4 = luteal phase) and PU groups (M1 = lowest E 2 , M2 = M1 + 7 d, M3 = M1 + 14 d, and M4 = M1 + 21 d) and twice in the CU group (active and inactive pill phases). After every blood sample, nightly HR and HRV were recorded and examined as an average from two nights.

RESULTS

Hormonal concentrations differed ( P < 0.05) between MC phases in the NM and PU groups, but not ( P ≥ 0.116) between the active and the inactive phases in the CU group. In the NM and PU groups, some of the HRV values were higher, whereas in the NM group, HR was lower during M2 compared with M3 ( P < 0.049) and M4 ( P < 0.035). In the CU group, HRV values ( P = 0.014-0.038) were higher, and HR was lower ( P = 0.038) in the inactive phase compared with the first week of the active phase.

CONCLUSIONS

The MC and the hormonal cycle phases influence autonomic nervous system balance, which is reflected in measurements of nocturnal HR and HRV. This should be considered when monitoring recovery in physically active individuals.

Cortisol Awakening Response and Heart Rate Variability in the Menstrual Cycle of Sportswomen

Purpose: This study aimed to examine the activities of heart rate variability (HRV) and cortisol secretion as markers of the autonomous nervous system (ANS) and the hypothalamic-pituitary-adrenal axis (HPA) during the menstrual cycle in female athletes. Method: Saliva samples of the participants (n = 28) were collected successively at 0, 15, 30, and 60 min after awakening to assess cortisol awakening response (CAR) during each of four phases of the menstrual cycle (the menstruation, ovulation, luteal, and premenstrual phases). Diurnal saliva samples were collected at noon, in the evening (17:00) and 22:00 for cortisol analysis. HRV was measured in the menstrual and premenstrual phases at rest (12:00-14:00). Results: There was no difference between CAR parameters in the menstrual phases. CAR parameters and diurnal cortisol levels were significantly correlated with each other throughout the menstrual cycle. Mean cortisol was a strong predictor of the area under the curve (AUC: S = 0.042; R-Sq = 98.4%). Time-dependent parameters of HRV (standard deviation of the N-N interval [SDNN; P = .049] and the root mean square of the successive R-R differences [rMSSD; P = .038]) were significantly higher in the menstrual phase. There were no correlations between CAR and HRV parameters. Conclusions: We suggest that the hypothalamic-pituitary-adrenal axis activity and the autonomic nervous system work in a separate manner that is not affected by the menstrual phases in sportswomen. The present study contributed to a better understanding of the relationship between the dynamics of cortisol release and the autonomic nervous system in different phases of the menstrual cycle in female athletes.

Taking context to heart: Momentary emotions, menstrual cycle phase, and cardiac autonomic regulation

Emotions have long been discussed in conjunction with the autonomic nervous system. Most research on emotion-autonomic linkages does not consider sex differences or an evident underlying mechanism for sex differences: menstrual cycle phase. Further, most research is limited to cross-sectional and laboratory studies. The degree to which emotion-autonomic associations manifest in everyday life may be different and may vary by sex and, for women, by menstrual cycle phase. This study employs the ambulatory monitoring of cardiovascular measures (e.g., heart rate and heart rate variability; HRV) and concurrent emotional states (e.g., sadness, stress, anxiety, anger, and happiness) in everyday life to better characterize emotion-autonomic associations as a function of sex and menstrual cycle phase. Participants (N = 174; 87 female) ages 18 to 46 (31.23 ± 6.49) were monitored over a 5-day observation period (one 2- and one 3-day session), using an ambulatory 24-hour electrocardiogram to monitor heart rate and ecological momentary assessment to record emotions every ~30 min. Women were monitored in both the early to mid-follicular and -luteal phases and men in two comparably distanced sessions. Multilevel models indicated that across sex, negative emotions and happiness were associated with elevated heart rate. Relative to men, women exhibited an elevated heart rate and reduced HRV during reports of anger. For women, during the luteal phase, but not follicular phase, momentary sadness, stress, and anxiety predicted increased heart rate and reduced HRV. These findings demonstrate the importance of considering sex and menstrual cycle phase in research investigating emotion-autonomic linkages.

Alterations in Cardiac Vagal Modulation-to-Vagal Tone Ratio in response to accumulated exercise stress in intermittent team sport

Study aim: This investigation examined the cardiac vagal modulation-to-vagal tone ratio and its utility to represent the dose response to accumulated exercise stress in intermittent team sport.

Material and methods: Fourteen international calibre female field hockey players training as part of a national team were participants over a three-week period. Exercise stress was expressed through cardiovascular strain using heart rate (HR) dynamics and was quantified as a training load (AU) and time spent exercising above anaerobic threshold (min). Cardiac autonomic activity was examined using heart rate variability; R-R intervals (ms) were collected immediately upon awakening throughout each weekend. The square root of the mean squared differences of successive R–R intervals were individually calculated, and log transformed prior to being averaged (Ln rMSSD) along with the corresponding mean R-R interval length. Multiple linear regression analysis examined the association between cardiac autonomic activity and indices of accumulated exercise stress.

Results: Significant inverse associations (95% CI) between the Ln rMSSD:R-R ratio and both training load [r = –0.48 (–0.70: –0.18), p = 0.012] and time spent exercising above anaerobic threshold [r = –0.51 (–0.72 : –0.22), p = 0.006] were observed. The association between mean R-R interval length and Ln rMSSD was not significant [r = 0.05, p = 0.950].

Conclusion: The current study demonstrated high intensity exercise, as defined through time spent above anaerobic threshold, displayed a stronger association with the Ln rMSSD:R-R ratio compared to a HR-derived training load when examining the dose response to accumulated intermittent exercise.

Reliability of short-term measurements of heart rate variability: Findings from a longitudinal study

Research on heart rate variability (HRV) received increasing attention. This study analysed the reliability of the most common HRV parameters for baseline measurements. 103 healthy students (83 women, M = 21.72 ± 3.31 years) participated in five short-term HRV sessions, each including supine, sitting, and standing positions, respectively, spanning a time interval of eleven months. Relative reliability was evaluated by intraclass correlation coefficients, and absolute reliability by standard errors of measurement, smallest real differences, and 95 % limits of random variation. No systematic mean differences between measurements emerged. Intraclass correlation coefficients were quite low (supine: .49-.64, sitting: .40-.57, standing: .35-.56). Absolute reliability indicators revealed pronounced variations between test and retest. Influences of posture and time between measurements on reliability were small and unsystematic. We conclude that such high levels of within-subjects variability in HRV measurements (a) hamper the detection of changes over time, and (b) should be considered carefully in future analyses.

A prospective study of sport injuries in youth females

OBJECTIVES

To examine sports and physical education (PE) injury rates in youth females during a school year and to investigate if an association exists between injury and phase of the menstrual cycle.

DESIGN

Prospective cohort.

SETTING

An online questionnaire was used to record training and competition exposure and self-reported injuries for 30-weeks.

PARTICIPANTS

103 PE students (12-15 years) from a girls' secondary school.

MAIN OUTCOME MEASURES

Injury rates and prevalence of acute, gradual onset/overuse and substantial injuries.

RESULTS

On average, girls trained 3.4 h/week and competed 1 h/week. During the study, 74 participants reported 595 injuries. The average weekly prevalence of all injuries was 20.7% (95% CI: 20.0-21.3), of which 8.6% (95% CI: 8.3-9.0) were acute injuries and 12.0% (95% CI: 11.4-12.6) were gradual onset/overuse injuries. The overall rate of sport and PE injuries was 10.4 injuries/1000 h of exposure. The most common acute injury involved the ankle (35%) while the most common gradual onset/overuse injury involved the knee (51%). There was no significant association between the stage of the menstrual cycle and the likelihood of injury (P = 0.18).

CONCLUSION

The high number of injuries in this population of girls suggests preventative measures, particularly targeting the lower extremity, are needed.

Consecutive non-training days over a weekend for assessing cardiac parasympathetic variation in response to accumulated exercise stress

Purpose: To examine the association between day-to-day resting cardiac parasympathetic variability over consecutive non-training days (i.e. weekend) and accumulated exercise stress when quantified using indices of cardiovascular strain. Methods: Twelve international calibre female field hockey players training as part of a national team were participants over a four-week mesocycle prior to a 2016 Olympic qualifying tournament. On-field exercise stress was examined using heart rate (HR) dynamics and quantified as; (1) training load and (2) time (min) spent above anaerobic threshold. The square root of the mean squared differences of successive cardiac cycles (R-R intervals) recorded on Saturday and Sunday were individually calculated and log-transformed prior to being averaged (Ln rMSSDweekend). Day-to-day variation in Ln rMSSD over the weekend was expressed using the coefficient of variation (Ln rMSSD_CV). Non-linear regression analysis examined the association between accumulated exercise stress and Ln rMSSD_CV. Results: A quadratic association between each index of exercise stress and Ln rMSSD_CV was identified. After converting the coefficient of determination into a correlation coefficient (90% CL), the respective association between Ln rMSSD_CV and training load (AU); r = 0.40 (0.16:0.59) and time above threshold; r = 0.35 (0.06:0.59) were observed. Conclusion: Ln rMSSD_CV derived over consecutive non-training days displayed a moderate, yet significant association between accumulated exercise stress when expressed as global or high-intensity indices of cardiovascular strain. Weekend assessments may offer a practical and appropriate juncture between microcycles to assess the magnitude of perturbation in cardiac autonomic homeostasis prior to entering subsequent training periods.

A Systematic Review and Meta-Analysis of Within-Person Changes in Cardiac Vagal Activity across the Menstrual Cycle: Implications for Female Health and Future Studies

Interest in cardiac vagal activity (CVA; e.g., parasympathetically-mediated heart rate variability) as a biomarker of physical and mental health has increased exponentially in recent years. However, the understanding of sources of within-person change (i.e., intra-individual variance) in CVA is lagging behind. This systematic review and meta-analysis summarizes and quantifies current empirical evidence of within-person changes in measures of CVA across the menstrual cycle in naturally-cycling premenopausal females. We conducted an extensive literature search following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement in five databases to identify observational studies with repeated measures of CVA in at least two menstrual cycle phases. A broad meta-analysis (n_studies = 37; n_individuals = 1,004) revealed a significant CVA decrease from the follicular to luteal phase (d = −0.39, 95% CI (−0.67, −0.11)). Furthermore, 21 studies allowed for finer-grained comparisons between each of two cycle phases (menstrual, mid-to-late follicular, ovulatory, early-to-mid luteal, and premenstrual). Significant decreases in CVA were observed from the menstrual to premenstrual (n_studies = 5; n_individuals = 200; d = −1.17, 95% CI (−2.18, −0.17)) and from the mid-to-late follicular to premenstrual phases (n_studies = 8; n_individuals = 280; d = −1.32, 95% CI (−2.35, −0.29)). In conclusion, meta-analyses indicate the presence of CVA fluctuations across the menstrual cycle. Future studies involving CVA should control for cycle phase. Recommendations for covarying or selecting cycle phase are provided.