Repeated Sprint Variations According to Circadian Rhythm at Different Menstrual Cycle Phases

• Abstract
• Introduction
• Materials and Methods
• Participants
• Study design
• Anthropometric assessments
• Determination of menstrual cycle phases
• Circadian hormone analysis
• Measurement of body temperature
• Determination of chronotype
• Determination of physiological and perceptual responses
• Blood lactate measurements
• Heart rate measurements
• Ratings of perceived exertion measurements
• Determination of performance variables
• Repeated sprint tests
• Statistical analysis
• Results
• Discussion
• Conclusion
• References

Abstract

This study assessed the repeated sprint performance in relation to circadian rhythm during different menstrual cycle phases (MCP). Twelve volunteer eumenorrheic women team sport athletes performed 5×6-s cycling sprints in morning (9 am to 10 am) and evening (6 pm to 7 pm) sessions during the mid-follicular (FP, 6^th–10^th d) and luteal phases (LP, 19^th–24^th d). Body weight, oral body temperature, resting heart rate and lactate levels together with estradiol, progesterone and cortisol levels were determined before tests. Relative peak and mean power and performance decrements were determined as performance variables and maximum heart rate, lactate and ratings of perceived exertion were determined as physiological variables. Evening body temperatures were significantly higher. Cortisol levels were higher in the morning and in the FP. Resting lactate levels did not vary with MCP or time of day, but a significant MCP x time of day interaction was observed. Body weight showed no change according to time of day and MCP. There was no significant effect of MCP and time of day on performance and physiological variables, in contrast, maximum lactate values were notably higher in the evening. In conclusion, MCP and time of day need not be considered during repeated sprint exercises of eumenorrheic women athletes.

Introduction

The topic of the menstrual cycle (MC) and its influence on athletic performance has gained popularity in the field of sport sciences, especially as more women engage in sport and exercise, recognizing the MC as a significant biological cycle in this context. It is widely acknowledged that eumenorrheic women have significant fluctuations in blood concentrations of female hormones throughout the MC. Specifically, they are low during the mid-follicular phase (FP) and high during the mid-luteal phase (LP), with both estrogen and progesterone peaking in the LP. Consequently, researchers have evaluated the interaction between exercise performance and the MC in relation to different menstrual cycle phases (MCP). Still, many studies have reported conflicting results. For instance, Sakamaki-Sunaga et al. [1] argued that variations in female hormones induced by MCP do not notably contribute to muscle hypertrophy and strength gains over a 12-week resistance training period. Giacomoni, Bernard, Gavarry, et al. [2] observed no significant difference in short-term maximal anaerobic performance across different MCPs. However, Gordon, Hughes, Young, et al. [3] found reduced muscle strength during the menstrual phase compared to FP, LP and premenstrual phases. Furthermore, Tsampoukos, Peckham, James, et al. [4] reported no significant differences in sprint performance and metabolic responses during the FP, LP, and ovulation phases. In another study, Brutsaert, Spielvogel, Caceres, et al. [5] noted an effect of the LP on ventilation and work outputs, yet the maximum oxygen consumption (VO_2max) remained unaffected by the MCP. Finally, Dokumaci and Hazir [6] found physiological variables at rest and during running economy tests to be consistent across different MCPs; however, running economy values measured were significantly better during the LP than the FP.

Another crucial biological factor potentially affecting exercise performance is the circadian rhythm (CR). CR pertains to the cyclic physiological changes that take place in the human body over 24 hours [7]. Within CR research, body temperature is viewed as the primary variable measured throughout the day, exhibiting its peak at around 6 pm and its nadir at around 6 am. Exercise performance appears to follow this CR of body temperature, showing improved performance in the evening (4 pm to 8 pm) compared to the morning (7 am to 10 am) [8]. However, when literature is searched conflicting results are found related to this topic. For instance, Kin-Isler [9] have found a CR effect in anaerobic performance of Wingate test which was not in accordance with changes in oral body temperature. In addition, Birch and Reilly [10] have found improved maximal voluntary contraction (MVC) during evening time (6 pm) together with increased body temperature; however, endurance time in MVC was not affected by time of day. Similarly, Essid, Cherif, Chtourou, et al. [11] indicated higher evening (6 pm) repeated sprint performance and ball throwing velocity in male handball players compared to morning (10 am) and afternoon (2 pm) performance and in a systematic review most studies reported an increase in afternoon (4 pm to 7:30 pm) anaerobic performance compared to morning (5:30 am to 11 am) [12]. On the contrary, in another study related to the influence of CR on sustained submaximal exercise, no CR effect was observed in MVC fatigue of elbow flexors even though oral body temperature was higher in the evening [13].

The circamensal rhythm, associated with the MC and the CR, affects body temperature and exercise [14]. Few studies have investigated the interaction of the circamensal rhythm and CR on exercise performance. Bambaeichi, Reilly, Cable, et al. [15] aimed to assess the effects of circamensal and diurnal changes on muscular strength. They found that while the interaction between CR and MCP was not evident in strength components, the MCP had a more pronounced effect on strength than CR. Literature has provided studies exploring how repeated sprint ability (RSA) varies by gender [16] and its fluctuations in women based on MCP [17] [18] [19]. While one study found that RSA was not influenced by the MCP [18], another identified that the average work and recovery oxygen consumption during 6-s sprints was higher during the LP than the FP [17]. Thus, the interaction of MCP and RSA presents mixed findings. Interestingly, only one study in existing literature has explored performance changes in repeated sprint tests (RST) based on the two biological rhythms. Tounsi, Jaafar, Aloui, et al. [20] assessed the combined effects of MCP and CR on various tests in female soccer players. Their findings revealed that while performance metrics were not impacted by MCP, mean RST durations were notably lower in the evening compared to the morning. On the other hand, jump test performance was significantly better in the evening. The scarcity of studies considering the outputs of RST based on the interaction of these two crucial biological rhythms underpins this research. Hence, this study aims to examine alterations in performance measures and physiological responses obtained from 5 × 6- s RST according to time of day during different MCPs. We hypothesized that performance metrics and physiological responses from 5 × 6- s RST will show statistical variance across different MCPs and times of day in eumenorrheic women athletes.

Materials and Methods

Participants

Initially nineteen healthy eumenorrheic women team sport athletes (basketball, volleyball and handball) who had a regular menstrual cycle for at least 6 months with a MC duration of 24–35 days volunteered to participate in this study. They did not use any hormones, oral contraceptives or other drugs, had no injury history, and did not receive any medical support for the past month. In addition their blood estradiol (E2) levels were between 85–220 pmol/L at FP and 230–750 pmol/L at LP, and blood progesterone (PRO) levels were less than 3 nmol/L at FP and more than 16 nmol/L at LP [21] [22]. Three athletes did not complete all of the measurements due to menstrual irregularities during measurements or injuries that was not related to the measurements. Additionally, four athletes’ E2 and PRO levels did not meet the inclusion criteria. Thus, the study was completed with 12 athletes ([Table 1]).

All athletes were informed about the possible risks and benefits of the study and signed a written informed consent. The study was approved by the Non-Interventional Clinical Researches Ethics board (decision no: GO 18/612–05) and conducted in accordance with the Declaration of Helsinki.

Study design

Participants attended the laboratory in the morning (9 am to 10 am) and evening (6 pm to 7 pm) during both the FP (6^th–10^th d) and LP (19^th–24^th d) of their MC [23]. The morning and evening visits were conducted on separate days and the order of testing was randomized for MCP and time of day ([Fig. 1]). Before performance days, participants also attended to the laboratory for familiarization session to the 5×6-s RST, to complete morningness/eveningness questionnaires and an information form to collect necessary information such as MC pattern of the last 6 months, oral contraceptive usage and drug history, sport injury history, date of birth, training age and training volume. Additionally, participants were informed to sleep for at least 8 hours before each test, to avoid intense physical activity the day before and on the day of the tests, and to stop consuming alcohol and caffeine before the tests. The first main RST sessions were conducted at least 24 h after the familiarization and main sessions were separated by at least 36 h [24].

Study design on the main test days is presented in [Fig. 2]. Body composition of the participants were measured by DXA Scanner (Lunar Prodigy Pro, GE Health Care, Madison Wisconsin, US) in FP morning sessions. The number of days for a total of 3 MC, including the MC in which the test was performed, were also recorded in case of any irregularity. Participants consumed a standard meal (10 kcal·kg^− 1) 2 hours before each test. Night-time sleep was recorded for each participant (FP Morning: 7.13±0.85 h; FP Evening: 8.0±1.58 h; LP Morning: 7.13±0.89 h; LP Evening: 8.41±1.07 h). When participants came to the laboratory 1 hour before the tests, blood samples were taken for the determination of E2, PRO and cortisol levels. Subsequently, participants were rested in a sitting position for 20 minutes while resting heart rate (HR) was recorded. Additionally, oral body temperature, body weight (BW) and resting lactate levels were measured.

Following standardized warm-up at cycle ergometer, participants were instructed to make 3 min stretching for lower extremity. After warm-up, participants performed a 5×6-s cycling RST with 30-s rest intervals on a mechanically braked cycle ergometer (Monark 894E Pike Bike, Sweden). Blood lactate measurements were taken immediately and every 2 min after the test until the maximal level is reached. Ratings of Perceived Exertion (RPE) values were recorded after each completed sprint during RST. HR were recorded throughout the test with 1-s intervals and the recovery period.

Anthropometric assessments

Height and BW values were measured with standardized methods [25]. Body fat percentages, fat mass, muscle mass (fat free soft tissue) and lean body mass were measured by DXA Scanner in the FP sessions [26]. Before use, the device was calibrated and the protocols recommended by the manufacturer were followed in the measurements. To ensure that the participants had optimal hydration status, urine specific gravity (Atago, URC-NE d 1.000 ̴ 1.050, Japan) was assessed before measurements and the cut-off point was determined as urine specific gravity≤1.030 [27].

Determination of menstrual cycle phases

The cycle length of participants was determined by counting the number of days from the cycle onset to the beginning of the next cycle. In addition to confirm MC of the participants’ serum concentrations of E2 and PRO were analyzed in FP between the 6^th and 10^th days and in the LP between the 20^th and 24^th days. A venous blood sample (approximately 8 mL) was collected from the antecubital vein into serum separation tubes on the test days before RST. Then, the blood sample was left to clot at room temperature for 40 minutes and centrifuged at 4,000 g for 8 min at 4°C (Eppendorf 5430 R, Canada). The serum samples were analyzed by ECLIA (Electrochemiluminescence Immunoessay) method using an auto analyzer (Roche Cobas e801, Germany). To verify that ovulation occurred during the cycle, two criteria were used: a rise in progesterone level from the follicular phase to the luteal phase and a minimum progesterone limit of 16 nmol·L^– 1 [21] [22].

Circadian hormone analysis

It is known that cortisol is considered to be a marker of psychophysiological stress and follow a diurnal variation throughout the day [28]. Hence cortisol concentrations were determined from blood samples taken before the tests, in order to detect its effects on RST performance. The blood sample was left to clot at room temperature for 40 minutes and centrifuged at 4,000 g for 8 min at 4°C (Eppendorf 5430 R, Canada). The serum samples were analyzed by ECLIA (Electrochemiluminescence Immunoessay) method using an auto analyzer (Roche Cobas e801, Germany).

Measurement of body temperature

Body temperature is accepted as the basic indicator of CR [29]. Therefore, resting oral body temperature (Omron Eco Temp Smart, Japan) was measured twice with a digital thermometer in both phases before each test, and the mean of the measurements was recorded as the oral body temperature.

Determination of chronotype

In order to determine the morning and evening preferences of the participants, the Turkish version [30] of “Morningness Eveningness Questionnaire” created by [31] was applied to the participants. According to the total scores obtained from 19 questions, individuals having 70–86 points were classified as “morning type (M-Type),” 59–69 points were classified as “moderately morning type,” 42–58 points were classified as “Neither type (N-Type),” 31–41 points were classified as "moderately evening type,” and finally 16–30 points were classifies as “evening type (E-Type)” [30].

Determination of physiological and perceptual responses

Blood lactate measurements

Blood lactate concentration was assessed by an enzymatic-amperometric method (Lactate Scout+, SensLab GmbH, Leipzig, Germany). The 0.5 µl blood samples taken from fingertip were immediately placed on a sample strip and inserted in the hand-held lactate analyzer for an immediate analysis before (LA_REST), immediately after, and every 2 min until the post-test peak lactate level was reached and a decrease was observed. The highest lactate response measured after the test was recorded as maximal lactate (LA_MAX). In addition, the net change in lactate (ΔLA) in MF and LF of the menstrual cycle and at different times of the day was calculated as the difference between maximal and resting lactate concentrations.

Heart rate measurements

Heart rate was measured at rest and during the RSTs with telemetric heart rate monitors (Polar-RS800; Polar Electro, Kempele, Finland) which can measure HR with 1-s intervals. Participants rested in sitting position for 20 min before tests and average of last 5 min was recorded as resting heart rate (HR_REST). The highest HR value measured during RSTs was recorded as maximal HR (HR_MAX).

Ratings of perceived exertion measurements

To determine how participants perceived the RST during different MCP and time of day, RPE values were recorded immediately after each sprint of the RSTs by using the Borg 6–20 RPE scale [32]. The highest RPE value was recorded as RPE_MAX.

Determination of performance variables

Repeated sprint tests

RST performances were evaluated with 5×6-s cycling RST with 30-s of passive recovery duration which provides a more valid assessment of repeated sprint activities in team sports [33]. The repeated sprint test was performed against a load of 10% of body weight without pedal acceleration (initial speed was zero ) [34]. During the RST inertial momentum of the pedal was not taken into consideration in calculation of the measured power outputs because it has been recommended to use higher resistive loads without acceleration in conditions where there is no chance of correcting inertia as in the present study [35].

Participants were asked to perform a warm-up consisted of 50–70 W cycling for 5 min with 5-s all-out sprints at 2^nd and 4^th min of cycling exercise following 3 min stretching exercise for the lower extremity. After warm-up, RSTs were conducted. The highest power output reached in each sprint and the average power output reached in each sprint recorded as relative peak power output (PP_REL) and mean power output (MP_REL), respectively. Performance decrement (PD%) was calculated using the following formula [36]:

Statistical analysis

Descriptive statistics (X̄  ± SD) for the outcome measures were calculated. The changes in the descriptive variables of hormones, performance and physiological responses to RST according to the time of day (morning and evening) and MCP (FP and LP) were analyzed using 2×2 repeated measures ANOVA. Partial eta square (η²) was calculated for the effect size and classified as 0.01=small effect, 0.06=medium effect, and 0.14=large effect [37]. Statistical analysis performed in the statistical package program (SPSS 20.0. USA) and the error level was determined as p<0.05.

Results

Descriptive results of participants are shown in [Table 1]. One participant was M-Type, one participant was E-Type while most of the participants were N-Type (n=10, 83.33%). In addition, MC days of participants were 29.25±2.30 days and urine-specific gravity that was measured before body composition measurements by DXA were 1021.00±7.76 which indicated that all participants were in a hydrated state.

The hormonal level of participants according to MCP and time of day are given in [Table 2]. E2 and PRO levels were significantly higher in LP as expected (E2: F_(1,11)=71.920, p<0.05, η²=0.867; PRO: F_(1,11)=180.259, p<0.05, η²=0.942). However, E2 and PRO levels were not affected by time of day (p>0.05) and there was no interaction between MCP and time of day (p>0.05). Cortisol levels were significantly higher in FP (p<0.05) and at morning sessions (p<0.05). Additionally, there was no interaction between MCP and time of day in cortisol levels (p>0.05).

Oral body temperature, which is the major CR indicator, was significantly higher in evening sessions (F_{(1, 11)}=12.424, p<0.05, η²=0.530); however, it was not affected by MCP and there was no interaction between MCP and time of day (p>0.05) ([Table 3]).

In BW and HR_REST, there were no significant MCP (BW: F_{(1, 11)}=2.305, p>0.05, η²=0.173; HR_REST: F_{(1, 11)}=0.203, p>0.05, η²=0.018) or time of day effects (BW: F_{(1, 11)}=0.350, p>0.05, η²=0.031; HR_REST: F_{(1, 11)}=4.621, p>0.05, η²=0.296), and there was no significant interaction between MCP and time of day (BW: F_{(1, 11)}=0.002, p>0.05, η²=0.001; HR_REST: F_{(1, 11)}=0.002, p>0.05, η²=0.001). LA_REST was not affected by MCP (F_{(1, 11)}=0.548, p>0.05, η²=0.047) and time of day (F_{(1, 11)}=3.104, p>0.05, η²=0.220). However, MCP x time of day interaction was significant (F_{(1, 11)}=7.765, p<0.05, η²=0.414) ([Fig. 3]). LA_REST values were low in the morning and high in the evening during FP, while high in the morning and low in the evening during LP.

Performance responses to RST are given in [Table 4]. In terms of performance variables PP_REL, MP_REL and PD% were not affected from MCP and time of day and MCP x time of day interaction was not significant (p>0.05).

The physiological responses to RST according to MCP and time of day are shown in [Table 5]. HR_MAX values were similar between different MCP and time of day, with no significant MCP x time of day interaction (p>0.05). LA_MAX was significantly higher at evening hours (F_{(1, 11)}=5.27, p<0.05, η²=0.324) ([Fig. 4]). However, there was no significant MCP effect (p>0.05) and MCP x time of day interaction (p>0.05). Additionally, in ΔLA, MCP (F_(1,11)=0.917, p=0.359, η²=0.077) and time of day effect (F_(1,11)=3.56, p=0.086, η²=0.245) and MCP x time of day interaction (F_(1,11)=0.145, p=0.711 η²=0.013) were not significant. Finally, RPE_MAX values were similar during different MCP and time of day, and MCP x time of day interaction was not significant (p>0.05).

Discussion

The purpose of this study was to examine the changes in repeated sprint performance according to time of day in different MCPs. In order to examine the changes, 12 eumenorrheic women team sport athletes participated 5×6-s RSTs with a 30 s passive rest periods on cycle ergometer in the morning and evening hours during FP and LP.

Major findings of the present study were that although E2 and PRO were higher in LP compared to FP, and cortisol was higher in FP than LP, performance variables of and physiological responses to RST were not different according to MCP and time of day except LA_MAX, which was higher during evening hours. In addition, oral body temperature was higher in the evening hours and did not follow any MCP change. Resting physiological responses did not show any MPC or time of day variations indicating that the participants were in similar physiological conditions before the RST. Although there was a significant MCP x time of day interaction in LA_REST, because there was no MCP or time of day effect, this interaction was negligible. In addition, neither MCP nor different times of day had an effect on BW of our participants indicating that there was no shift of body fluids across several intra- and extra-cellular body fluid compartments due to MCP or time of day which is similar to findings related to BW changes according to MCP and time of day [6] [38].

E2 and PRO hormones, which were analyzed to confirm the MCPs of the participants, were significantly higher in LP [23] and were in the accepted range [21] [22]. On the other hand, these hormones were not affected by time of day. Although the studies investigating the effect of CR on ovarian hormones are limited in the literature, there is one study that reported significantly higher PRO concentration in the morning [39]. Cortisol levels that were analyzed to determine the time of day effects were significantly higher in FP and morning sessions. As is known, cortisol, which is considered to be a marker of psychophysiological stress and is associated with a decrease in sport performance, peaks in the morning under normal conditions [40] [41]. There are various results in the literature regarding the changes of cortisol according to MCP. While some of the studies reported higher but not statistically significant cortisol levels in LP [42], others reported no increase for this hormone [43]. In contrast, Hamidovic, Karapetyan, Serdarevic, et al. [44] revealed in their meta-analysis that higher levels of allopregnanolone (a product of PRO) during LP could have effects that decrease circulating cortisol levels, which results in significantly higher cortisol levels during FP. In this study, cortisol hormone was significantly higher in the morning hours and also in FP in accordance with the literature.

As stated before, body temperature is generally considered as the primary endogenous indicator of the CR [45], and studies indicate that body temperature increases in the LP due to the thermogenic effects of PRO [23]. In addition, the peak body temperature, which occurs in the first part of the evening, has been shown to lead to higher carbohydrate utilization and to facilitate the mechanics of the actin-myosin cross bridge in the muscle unit [46]; this in turn cause an increase in short term maximal performance. In general studies related to time of day and sports performance mostly indicate an association between body temperature and short term maximal performance [47]; however, our study failed to find such an association. Although there was a significant increase in body temperature in the evening hours, this increase did not lead to any performance change according to time of day. Perhaps about 0.2 C°, which corresponds to about 0.55% increase in body temperature in the evening period in the present study, was not enough to cause a performance change in RST performance.

As indicated previously, PP_REL, MP_REL and PD% values obtained from RSTs did not vary according to MCPs and time of the day. In a study planned to investigate the effect of different MCPs on RSP and the rate of lactate removal during active recovery, it was reported that the MCP effect was not significant in PP_REL values, in line with our study [18]. Similarly, in the study of Middleton and Wenger [17], in which the effects of high-intensity interval training performed in two different phases of MC (FP and LP), on performance and recovery were investigated, it was revealed that the phase effect was not significant in PP_REL values compared to the present study. In another study conducted to investigate the effects of MCP on sprinting, recovery, and metabolic responses, it was reported that there was no MCP effect in absolute MP values, which is similar to our study [4]. The fact that MCP effect was not observed in PP_REL and MP_REL in our study could be explained by non-existent premenstrual or menstrual syndrome of participants during the tests, as suggested in Giacomoni, Bernard, Gavarry, et al. [2]. The authors suggested that exercise performance would not be affected by MCP as long as the participants did not experience premenstrual or menstrual syndrome at the time of testing [2].

Our results related to time of day effects in RST performance is somehow contradictory to the studies in the literature. For instance, according to the systematic review, afternoon anaerobic performance was found to be higher than morning performance [12] and in another study ball throwing velocity and RST performance were found to be higher in the evening (6 pm) than in the morning (10 am) and afternoon (2 pm) [11]. In addition some other studies [48] reported that the PP_REL was affected by the time of day, and these studies indicated that PP_REL was higher in the evening hours. Pullinger, Oksa, Clark, et al. [49] revealed that MP_ABS values are affected by the time of day and this variable is higher in the evening hours. In our study, the test hours (9 am to 10 am and 6 pm to 7 pm) selected in order to evaluate the effect of time of day were determined as the hours when the performance differences in the literature were determined in general. However, the fact that the tests were limited to two different times of the day may not have been sufficient to detect significant time of day effects on PP_REL and MP_REL values. Together with these findings, our results showed that PD% was not affected by MCP and time of day. This result is in line with several studies in the literature. For instance, Hazir, Akdogan and Acikada [18] stated that the MCP effect was not significant in PD% values after 5×6-s RST and Graja, Kacem, Hammouda, et al. [19] also reported that PD% values were the same in LP when compared to FP, but were significantly lower compared to the premenstrual phase. Spencer, Bishop, Dawson, et al. [33] stated in their review that the PD% values in RSTs performed with 30-second passive rest intervals, as in our study, was around 10%, and this decrease was less as the rest interval lengthened. The similarity of PD% values in our study at different times of the day and in different MCPs may be due to the 30 sec recovery time between sprints, which is considered to be the optimal rest interval during RSTs. As stated before body temperature, E2, PRO and cortisol values showed variations through MCP and time of day. However, the changes in these hormones and body temperature were not reflected in the performance variables of RST.

In terms of physiological responses, our results indicated that HR (HR_MAX and HR_MEAN) and RPE (RPE_MAX) were not affected by MCP and time of day, while LA_MAX was affected from time of day, evening hours being higher than morning hours, with no effect of MCP. In terms of HR some studies investigating the effects of MCP on HR, reported no change in HR according to MCP [6] [50] as in the present study. In addition, in the study of Birch and Reilly [10] it was found that HR_MAX responses did not show variations according to MCP and time of day after maximal isometric lifting in ten eumenorrheic women with moderate physical activity levels. In the present study we have found significant increase in body temperature in the evening period which is about 0.2°C however, this increase is only about 0.55% which might be not enough to cause any time of day change in HR responses. In addition, it is known that increased PRO has a thermogenic effect on body temperature [51] and since PRO is high during LP it was expected to have an increased body temperature responses and hence HR responses during LP due to changes in plasma volume and blood viscosity [52]. However, our results failed to show any MCP effect on body temperature, which also might be the reason for not finding a significant MCP change in HR responses.

Studies related to MCP and time of day effects in RPE according to maximal exercise show similarities with our findings [48] [50]. Since RPE is an assessment method that can be influenced by factors such as the participant's personality, motivation, and attention [53], similar RPE responses according to MCP and time of day obtained in our study might be due to similarities in these factors. In addition, most of our participants were N-Type chronotypes (83.33%) and it has been suggested that N-Type individuals are less likely to be affected from time of day [54]. In addition, as stated previously, in the present study HR responses did not show any circadian or MCP changes, and RPE, which is known to be closely associated with HR responses to exercise [55], did not show any MCP and circadian variation; this is probably because of factors related to HR responses, which also showed no variation according to MCP and CR.

LA_MAX, is the only physiological variable that showed a significant time of day effect in this study, evening LA_MAX, was higher than the morning values, with no MCP effect and MCP x time of day interaction. On the contrary, ΔLA showed no MCP or time of day effect in the present study. In the literature, there are studies investigating the effects of MCP on lactate, which, in line with our study, showed that this variable did not change according to MCP [6] [18] [19]. In a study conducted to evaluate the effect of MCP on physical, neuromuscular and biochemical responses to RST in female handball players [19], it was reported that LA values measured after RST were not affected by MCP, in line with our study. In studies investigating the effect of time of day on LA_MAX values, there are studies showing that this variable is affected by the time of day, similar to our study, and that this variable is higher in the evening hours [56], but studies reporting that the effect of time of day on LA_MAX was not significant [9] are also available. In the study of Forsyth and Reilly [24] to investigate the combined effects of MCP and time of day on the lactate threshold, it was revealed that the MCP x time of day interaction was not significant in the lactate variable [24], similar to our study. In our study, the fact that LA responses were not affected by MCP might have resulted from the fact that the 30-s passive rest intervals given during RSTs were sufficient for LA removal, although exercise metabolism did not change in MCPs. On the other hand, it could be that the significantly higher LA_MAX values in the evening are due to the body temperature, which is also significantly higher in the evening, but was not affected by MCP. It has been reported that the increase in body temperature increased the activity of phosphofructokinase and lactate dehydrogenase enzymes, and as a result, lactate production during exercise increased [24].

It is known that chronotype is a measure of individual differences in rest/activity or circadian timing [57]. When the chronotype of the participants are taken into consideration it is seen that 10 of 12 participants (83.33%) were N-Type, which indicated that they were not affected by extreme chronotypes. In other words, it is known that N-Type individuals do not have a preference in exercise timing in terms of morning or evening [54]. Hence we can say that the reason for not finding significant differences in performance and physiological responses to RST in the present study might be due to chronotype of most of the participants. As is known, morning-type individuals prefer to exercise in the morning while evening types prefer evening for exercising, and N-Types have no preference related to this [54] [58].

This study has some limitations. We examined the responses to RST at two different time points (9 am to 10 am and 6 pm to 7 pm) in only two phases of the MC, namely FP and LP. In addition, although the researchers ensured that the participants consumed diets with similar content on the test days, the fact that food consumption records of participants were not tracked during the study can also be considered as a limitation.

Conclusion

Our results suggest that MCP and time of day had no effect on performance and physiological responses to RST in eumenorrheic women athletes. Hence, we can say that women athletes can participate in their training and competition programs related to RST performance without considering their MCP or time of day. However, as indicated before changes in RST performance were only evaluated in MP and LP; therefore, adding performance evaluation during the ovulation phase or more broadly into five phases as early follicular, late follicular, ovulation, early and late luteal is recommended for future research. In terms of time of day, evaluating RST performance at more frequent time points such as 2 to 4 hours can also be performed to clearly determine the CR effect. In addition, since most of the athletes in this study were N-Type, including mostly morning and evening-type athletes in future research is also recommended to better understand the time of day and MCP effect on RST performance in women athletes.

Conflict of Interest

The authors report no conflict of interest.

Acknowledgement

This study was supported by Hacettepe University Scientific Research Projects Coordination Unit Ph.D. Thesis Grant (Project No.: TDK-2018–17487). The authors would like to thank to Assist. Prof. Dr. Ferhat ESATBEYOGLU, Res. Asistants M. Goren KOSE and Y. Emre EKINCI for their valuable help in data collection. The authors also would like to thank to participants who volunteered for this study.

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• 38 Rael B, Romero-Parra N, Alfaro-Magallanes VM. et al. Body Composition Over the Menstrual and Oral Contraceptive Cycle in Trained Females. Int J Sports Physiol Perform 2021; 16: 375-381
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• 39 Syrop CH, Hammond MG. Diurnal variations in midluteal serum progesterone measurements. Fertil Steril 1987; 47: 67-70
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• 41 Vitale JA, Weydahl A. Chronotype, Physical Activity, and Sport Performance: A Systematic Review. Sports Med (Auckland, NZ) 2017; 47: 1859-1868
  CrossrefPubMedSearch in Google Scholar
• 42 De Souza MJ, Maguire MS, Maresh CM. et al. Adrenal activation and the prolactin response to exercise in eumenorrheic and amenorrheic runners. J Appl Physiol 1991; 70: 2378-2387
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• 43 Kraemer RR, Francois M, Webb ND. et al. No effect of menstrual cycle phase on glucose and glucoregulatory endocrine responses to prolonged exercise. Eur J Appl Physiol 2013; 113: 2401-2408
  CrossrefPubMedSearch in Google Scholar
• 44 Hamidovic A, Karapetyan K, Serdarevic F. et al. Higher Circulating Cortisol in the Follicular vs. Luteal Phase of the Menstrual Cycle: A Meta-Analysis. Front Endocrinol (Lausanne) 2020; 11: 311
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• 45 Thun E, Bjorvatn B, Flo E. et al. Sleep, circadian rhythms, and athletic performance. Sleep Med Rev 2015; 23: 1-9
  CrossrefPubMedSearch in Google Scholar
• 46 Starkie RL, Hargreaves M, Lambert DL. et al. Effect of Temperature on Muscle Metabolism During Submaximal Exercise in Humans. Exp Physiol 1999; 84: 775-784
  CrossrefPubMedSearch in Google Scholar
• 47 Robinson WR, Pullinger SA, Kerry JW. et al. Does Lowering Evening Rectal Temperature to Morning Levels Offset the Diurnal Variation in Muscle Force Production?. Chronobiol Int 2013; 30: 998-1010
  CrossrefPubMedSearch in Google Scholar
• 48 Frikha M, Chaâri N, Souissi N. Effect of sport practice and warm-up duration on the morning-evening difference in anaerobic exercise performance and perceptual responses to it. Biol Rhythm Res 2015; 46: 497-509
  CrossrefPubMedSearch in Google Scholar
• 49 Pullinger SA, Oksa J, Clark LF. et al. Diurnal variation in repeated sprint performance cannot be offset when rectal and muscle temperatures are at optimal levels (38.5 C). Chronobiol Int 2018; 35: 1054-1065
  CrossrefPubMedSearch in Google Scholar
• 50 O'Leary CB, Lehman C, Koltun K. et al. Response of testosterone to prolonged aerobic exercise during different phases of the menstrual cycle. Eur J Appl Physiol 2013; 113: 2419-2424
  CrossrefPubMedSearch in Google Scholar
• 51 Baker FC, Siboza F, Fuller A. Temperature regulation in women: Effects of the menstrual cycle. Temperature (Austin) 2020; 7: 226-262
  CrossrefPubMedSearch in Google Scholar
• 52 Moran VH, Leathard HL, Coley J. Cardiovascular functioning during the menstrual cycle. Clin Physiol 2000; 20: 496-504
  CrossrefPubMedSearch in Google Scholar
• 53 Morgan WP. Psychological components of effort sense. Med Sci Sports Exerc 1994; 26: 1071-1077
  CrossrefPubMedSearch in Google Scholar
• 54 Adan A, Archer SN, Hidalgo MP. et al. Circadian Typology: A Comprehensive Review. Chronobiol Int 2012; 29: 1153-1175
  CrossrefPubMedSearch in Google Scholar
• 55 Scherr J, Wolfarth B, Christle JW. et al. Associations between Borg’s rating of perceived exertion and physiological measures of exercise intensity. Eur J Appl Physiol 2013; 113: 147-155
  CrossrefPubMedSearch in Google Scholar
• 56 Pullinger SA, Brocklehurst EL, Iveson RP. et al. Is there a diurnal variation in repeated sprint ability on a non-motorised treadmill?. Chronobiol Int 2014; 31: 421-432
  CrossrefPubMedSearch in Google Scholar
• 57 Taylor BJ, Hasler BP. Chronotype and Mental Health: Recent Advances. Curr Psychiatry Rep 2018; 20: 59
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• 58 Polańska S, Karykowska A, Pawelec Ł. Associations between chronotype and physical activity and well-being in adults. Chronobiol Int. 2024 41. 1-9
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Correspondence

Publication History

Received: 30 May 2024

Accepted: 21 August 2024

Accepted Manuscript online:
21 August 2024

Article published online:
23 September 2024

© 2024. Thieme. All rights reserved.

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany

• References

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  CrossrefPubMedSearch in Google Scholar
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• 23 De Jonge XAJ. Effects of the menstrual cycle on exercise performance. Sports Med 2003; 33: 833-851
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• 24 Forsyth JJ, Reilly T. The combined effect of time of day and menstrual cycle on lactate threshold. Med Sci Sport Exer 2005; 37: 2046-2053
  CrossrefPubMedSearch in Google Scholar
• 25 Heyward HV, Stolarczyk LM. Applied Body Composition Assessment Human Kinetics. 1996
  PubMedSearch in Google Scholar
• 26 Kosar SN, Guzel Y, Kose MG. et al. Whole and segmental body composition changes during mid-follicular and mid-luteal phases of the menstrual cycle in recreationally active young women. Ann Hum Biol 2022; 49: 124-132
  CrossrefPubMedSearch in Google Scholar
• 27 Zubac D, Reale R, Karnincic H. et al. Urine specific gravity as an indicator of dehydration in Olympic combat sport athletes; considerations for research and practice. Eur J Sport Sci 2018; 18: 920-929
  CrossrefPubMedSearch in Google Scholar
• 28 Sedliak M, Finni T, Cheng S. et al. Effect of time-of-day-specific strength training on serum hormone concentrations and isometric strength in men. Chronobiol Int 2007; 24: 1159-1177
  CrossrefPubMedSearch in Google Scholar
• 29 Waterhouse J, Drust B, Weinert D. et al. The circadian rhythm of core temperature: origin and some implications for exercise performance. Chronobiol Int 2005; 22: 207-225
  CrossrefPubMedSearch in Google Scholar
• 30 Punduk Z, Gur H, Ercan I. A reliability study of the Turkish version of the morningness-eveningness questionnaire. Turk Psikiyatri Derg 2005; 16: 1-6
  PubMedSearch in Google Scholar
• 31 Horne JA, Ostberg O. A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. Int J Chronobiol 1976; 4: 97-110
  PubMedSearch in Google Scholar
• 32 Borg G, Hassmén P, Lagerström M. Perceived exertion related to heart rate and blood lactate during arm and leg exercise. Eur J Appl Physiol Occup Physiol 1987; 56: 679-685
  CrossrefPubMedSearch in Google Scholar
• 33 Spencer M, Bishop D, Dawson B. et al. Physiological and metabolic responses of repeated-sprint activities: Specific to field-based team sports. Sports Med 2005; 35: 1025-1044
  CrossrefPubMedSearch in Google Scholar
• 34 Billaut F, Bishop DJ, Schaerz S. et al. Influence of knowledge of sprint number on pacing during repeated-sprint exercise. Med Sci Sports Exerc 2011; 43: 665-672
  CrossrefPubMedSearch in Google Scholar
• 35 Bogdanis G, Papaspyrou A, Lakomy H. et al. Effects of inertia correction and resistive load on fatigue during repeated sprints on a friction-loaded cycle ergometer. J Sports Sci 2008; 26: 1437-1445
  CrossrefPubMedSearch in Google Scholar
• 36 Girard O, Mendez-Villanueva A, Bishop D. Repeated-sprint ability—part I: Factors contributing to fatigue. Sports Med 2011; 41: 673-694
  CrossrefPubMedSearch in Google Scholar
• 37 Richardson JT. Eta squared and partial eta squared as measures of effect size in educational research. Educ Res Rev 2011; 6: 135-147
  CrossrefPubMedSearch in Google Scholar
• 38 Rael B, Romero-Parra N, Alfaro-Magallanes VM. et al. Body Composition Over the Menstrual and Oral Contraceptive Cycle in Trained Females. Int J Sports Physiol Perform 2021; 16: 375-381
  CrossrefPubMedSearch in Google Scholar
• 39 Syrop CH, Hammond MG. Diurnal variations in midluteal serum progesterone measurements. Fertil Steril 1987; 47: 67-70
  CrossrefPubMedSearch in Google Scholar
• 40 Tafet GE, Idoyaga-Vargas VP, Abulafia DP. et al. Correlation between cortisol level and serotonin uptake in patients with chronic stress and depression. Cogn Affect Behav Neurosci 2001; 1: 388-393
  CrossrefPubMedSearch in Google Scholar
• 41 Vitale JA, Weydahl A. Chronotype, Physical Activity, and Sport Performance: A Systematic Review. Sports Med (Auckland, NZ) 2017; 47: 1859-1868
  CrossrefPubMedSearch in Google Scholar
• 42 De Souza MJ, Maguire MS, Maresh CM. et al. Adrenal activation and the prolactin response to exercise in eumenorrheic and amenorrheic runners. J Appl Physiol 1991; 70: 2378-2387
  CrossrefPubMedSearch in Google Scholar
• 43 Kraemer RR, Francois M, Webb ND. et al. No effect of menstrual cycle phase on glucose and glucoregulatory endocrine responses to prolonged exercise. Eur J Appl Physiol 2013; 113: 2401-2408
  CrossrefPubMedSearch in Google Scholar
• 44 Hamidovic A, Karapetyan K, Serdarevic F. et al. Higher Circulating Cortisol in the Follicular vs. Luteal Phase of the Menstrual Cycle: A Meta-Analysis. Front Endocrinol (Lausanne) 2020; 11: 311
  CrossrefPubMedSearch in Google Scholar
• 45 Thun E, Bjorvatn B, Flo E. et al. Sleep, circadian rhythms, and athletic performance. Sleep Med Rev 2015; 23: 1-9
  CrossrefPubMedSearch in Google Scholar
• 46 Starkie RL, Hargreaves M, Lambert DL. et al. Effect of Temperature on Muscle Metabolism During Submaximal Exercise in Humans. Exp Physiol 1999; 84: 775-784
  CrossrefPubMedSearch in Google Scholar
• 47 Robinson WR, Pullinger SA, Kerry JW. et al. Does Lowering Evening Rectal Temperature to Morning Levels Offset the Diurnal Variation in Muscle Force Production?. Chronobiol Int 2013; 30: 998-1010
  CrossrefPubMedSearch in Google Scholar
• 48 Frikha M, Chaâri N, Souissi N. Effect of sport practice and warm-up duration on the morning-evening difference in anaerobic exercise performance and perceptual responses to it. Biol Rhythm Res 2015; 46: 497-509
  CrossrefPubMedSearch in Google Scholar
• 49 Pullinger SA, Oksa J, Clark LF. et al. Diurnal variation in repeated sprint performance cannot be offset when rectal and muscle temperatures are at optimal levels (38.5 C). Chronobiol Int 2018; 35: 1054-1065
  CrossrefPubMedSearch in Google Scholar
• 50 O'Leary CB, Lehman C, Koltun K. et al. Response of testosterone to prolonged aerobic exercise during different phases of the menstrual cycle. Eur J Appl Physiol 2013; 113: 2419-2424
  CrossrefPubMedSearch in Google Scholar
• 51 Baker FC, Siboza F, Fuller A. Temperature regulation in women: Effects of the menstrual cycle. Temperature (Austin) 2020; 7: 226-262
  CrossrefPubMedSearch in Google Scholar
• 52 Moran VH, Leathard HL, Coley J. Cardiovascular functioning during the menstrual cycle. Clin Physiol 2000; 20: 496-504
  CrossrefPubMedSearch in Google Scholar
• 53 Morgan WP. Psychological components of effort sense. Med Sci Sports Exerc 1994; 26: 1071-1077
  CrossrefPubMedSearch in Google Scholar
• 54 Adan A, Archer SN, Hidalgo MP. et al. Circadian Typology: A Comprehensive Review. Chronobiol Int 2012; 29: 1153-1175
  CrossrefPubMedSearch in Google Scholar
• 55 Scherr J, Wolfarth B, Christle JW. et al. Associations between Borg’s rating of perceived exertion and physiological measures of exercise intensity. Eur J Appl Physiol 2013; 113: 147-155
  CrossrefPubMedSearch in Google Scholar
• 56 Pullinger SA, Brocklehurst EL, Iveson RP. et al. Is there a diurnal variation in repeated sprint ability on a non-motorised treadmill?. Chronobiol Int 2014; 31: 421-432
  CrossrefPubMedSearch in Google Scholar
• 57 Taylor BJ, Hasler BP. Chronotype and Mental Health: Recent Advances. Curr Psychiatry Rep 2018; 20: 59
  CrossrefPubMedSearch in Google Scholar
• 58 Polańska S, Karykowska A, Pawelec Ł. Associations between chronotype and physical activity and well-being in adults. Chronobiol Int. 2024 41. 1-9
  PubMedSearch in Google Scholar