Post-Exercise Hypotension and Reduced Cardiac Baroreflex after Half-Marathon Run: In Men, but Not in Women

examined whether trained women exhibit similar cardiovascular and cardiac barore ex alterations after a half-marathon compared to men. Thirteen women (39.1 9.3 years; 165 6 cm; 58.2 7.5 kg; maximal aerobic speed (MAS): 13.7 2.2 km h 1 ) and 12 men (45.7 10.5 years; 178 7 cm; 75.0 8.3 kg; MAS: 15.8 2.2 km h 1 ) ran an o cial half-marathon. Before and 60-min after, cardiovascular variables, parasympathetic (heart rate variability analysis) modulation and cardiac barore ex function (transfer function and sequence analyses) were assessed during supine rest and a squat-stand test. Running performance was slower in women than in men (120 19 vs. 104 14 min for women and men, respectively). However, when expressed as a percentage of MAS, it was similar (78.1 4.6% and 78.2 5.4% of MAS for women and men, respectively). Before the run, women exhibited lower mean blood pressure (BP), cardiac output

rest and a squat-stand test. Running performance was slower in women than in men (120 19 vs. 104 14 min for women and men, respectively). However, when expressed as a percentage of MAS, it was similar (78.1 4.6% and 78.2 5.4% of MAS for women and men, respectively). Before the run, women exhibited lower mean blood pressure (BP), cardiac output (CO) and stroke volume (SV) compared to men, together with higher parasympathetic indexes. After the race, parasympathetic indexes decreased in both sexes, but remained higher in women. Reduced SV, systolic BP and cardiac barore ex were observed in men but not in women. Contrary to men, a competitive half-marathon did not trigger post-exercise hypotension and a reduced cardiac barore ex in women. Keywords:barore ex; sympathetic; parasympathetic; squat stand test; half-marathon; sex; running 1. Introduction Cardiovascular disease (CVD) is the leading cause of mortality amongst women worldwide [1,2], making the reduction of CVD risk a crucial factor in reducing mortality [3]. A healthy lifestyle that reduces the risk of CVD should include at least 150 min per week of moderate-intensity aerobic exercise, 75 min per week of vigorous-intensity aerobic exercise or an equivalent combination of the two intensities [4,5]. Int. J. Environ. Res. Public Health2020,17, 6337; doi:10.3390 /ijerph17176337 /journal/ijerph

Int. J. Environ. Res. Public Health2020,17, 6337 2 of 13 Accordingly, women are more and more involved in leisure-time running and competitive running events, including running races from 5 km to ultramarathons in distance (>42.2 km) [6,7]. Despite the female sex being well represented in all the di erent race distances, recent surveys about running event participation reveal that women make up a greater proportion of participants in shorter distance events when compared to longer events [8]. For instance, at races in Switzerland, the number of females completing half marathon is ~12 times higher than marathons [9]. Long-duration and intense physical challenges may reveal cardiac dysfunction that is otherwise compensated for at rest, and a U-shaped relationship between exercise and cardiac morbidity exists[5,10]. Fortunately, the overall risk of sudden death during exercise is considered low (between 0.1 and 38/100,000 person-years), and comparable to that of the general population, meaning that 20% of all sudden death cases are still recorded during exercise [11]. Most deaths can be attributable to underlying cardiac abnormalities where exercise is a mere trigger for a fatal event rather than the actual cause of death [11], together with changes in the autonomic nervous system (ANS) activity. Indeed, dynamic exercise is associated with a shift towards sympathetic dominance during the exercise and after its cessation [12–14], potentially leading to an increase in susceptibility to sudden cardiovascular events [15]. In particular, post-exercise recovery (mainly in the rst 30 min and especially after vigorous exercise [16]) is a critical phase for sudden cardiovascular events. This is attributable to increased sympathetic and decreased parasympathetic nerve activity [17]. Depending on exercise and individual's characteristics, complete autonomic recovery may take even longer [18]. Whether a speci c sex-di erence in cardiovascular events triggered by exercise is still debated, since studies both suggest a lower atrial brillation risk in women but also an increased risk at lower intensities of exercise [19]. The ANS responses need additional research as well. Indeed, it is well established that at rest, young, pre-menopausal women have greater parasympathetic activity and reduced sympathetic activity [20,21]. This leads to a di

by exercise is still debated, since studies both suggest a lower atrial brillation risk in women but also an increased risk at lower intensities of exercise [19]. The ANS responses need additional research as well. Indeed, it is well established that at rest, young, pre-menopausal women have greater parasympathetic activity and reduced sympathetic activity [20,21]. This leads to a di erent cardiovascular regulation by the ANS with lower resting blood pressure (BP) values in women, and they tend to experience orthostatic hypotension and fainting more frequently than men [22]. Whether these autonomic di erences persist during exercise and into early recovery is unclear and seems to depend on the training status and the type of exercise. For instance, greater vagal withdrawal during ramp-type exercise below the anaerobic threshold has been suggested in sedentary women [23]. On the contrary, during an acute supramaximal exercise (Wingate test), a lower sympatho-adrenergic response has been reported in female compared to male athletes [24]. Paradoxically, after such an exercise, a greater parasympathetic withdrawal during the recovery was reported in women [25]. Overall, it suggests that despite the fact that women exhibit a more favorable resting autonomic pro le, they experience greater autonomic alterations after a single bout of supramaximal exercise. Alongside these observations, hemodynamic determinants of post-exercise hypotension (post-exercise reduction in BP) are likely to di er between sexes and need further investigation especially with intense exercise involving trained participants [26,27]. However, autonomic and cardiovascular responses to endurance exercise have been poorly studied in trained women, despite years of recognition that sex in uences physiological responses to exercise. In recent decades, many research groups have pointed out this weakness [28] and it is essential to further characterize women's response in this area. Thus, the aim of our study was to investigate the e ect of an acute, competitive endurance exercise bout (21 km run competition) on cardiovascular and autonomic responses in trained women and men. In accordance with previous observations made after intense exercise, our hypothesis was that trained women would show greater alterations in cardiovascular and parasympathetic responses to a half-marathon than trained men.

of our study was to investigate the e ect of an acute, competitive endurance exercise bout (21 km run competition) on cardiovascular and autonomic responses in trained women and men. In accordance with previous observations made after intense exercise, our hypothesis was that trained women would show greater alterations in cardiovascular and parasympathetic responses to a half-marathon than trained men.

Int. J. Environ. Res. Public Health2020,17, 6337 3 of 13 2. Materials and Methods 2.1. Participants This cross-sectional study involved 25 volunteer amateur runners: 13 healthy, non-pregnant, pre-menopausal women with regular menstruation (menstrual cycle ranges from 25 to 32 days) and 12 men. Although limited, this sample size is in accordance with previous studies on ANS using a similar design [25,29–31]. They were recruited within the Run for Science event, hosted by the University of Verona (Italy) in April 2019 [31]. The inclusion criteria were a history of regular recreational running training (mean training regimen of 220 min/week) for more than ve years and having previously nished a half-marathon in the previous two years. The presence of disease, pharmacological treatment, cigarette smoking, alcohol (more than six glasses per week) or co ee (more than four cups per day) abuse were exclusion criteria determined by standard medical examination. All participants provided their written informed consent before participating in the experiments. The study was approved by the local Ethical Committee (Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; protocol number 165038) and performed in accordance with the Helsinki Declaration of 1975. 2.2. Study Protocol Maximal oxygen uptake ( . V O2max), maximal aerobic speed (MAS) and the speeds associated with the first (VT1) and second (VT2) ventilatory thresholds were determined by an incremental treadmill running test at the laboratory, following procedures already described [32]. VT1 and VT2 were determined with the “respiratory equivalent” method, based on breath by breath measures of . V O2, carbon dioxide production ( . V CO2) and ventilation ( . V E), with the values being averaged every 10 s. The . V E/ . V O2and . V E/ . V CO2ratios were plotted against time during the incremental exercise test. VT1 corresponds to a first nonlinear increase in the . V E/ . V O2curve, while the . V E/ . V CO2slope remains constant. In addition, VT2 is indicated by the nonlinear increase in the . V E/ . V CO2curve concomitant to a second strong increase in . V

were plotted against time during the incremental exercise test. VT1 corresponds to a first nonlinear increase in the . V E/ . V O2curve, while the . V E/ . V CO2slope remains constant. In addition, VT2 is indicated by the nonlinear increase in the . V E/ . V CO2curve concomitant to a second strong increase in . V E/ . V O2with a further increase in exercise intensity. Briefly, the protocol test was individualized for each participant to control the duration of each test (incremental phases lasted 8–12 min). Therefore, the initial speed was determined by the participant's capacity, and it was increased by 0.5 km/h every minute until exhaustion. The running surface slope was kept at a constant+1% throughout the test (Runrace Technogym, Gambettola, Italy). Oxygen uptake and ventilatory parameters were determined breath-by-breath using a Cosmed metabolic cart (Quark PFT, Cosmed Rome, Italy). No more than 15 days later, participants competed in an official half-marathon race certified by the Italian Track and Field Federation. The day of the race, the weather was sunny, with no wind, the air temperature was 19 C with 71% humidity (stable throughout the duration of the event). Participants were instructed to fast for at least 3 h before testing, to refrain from ingesting beverages containing caffeine and alcohol and not to exercise (beyond normal lifestyle activities) for at least 24 h prior to testing. To avoid many people reaching the testing station simultaneously, the participants started the race in waves (from 7:30 to 10:00 a.m.) scheduled based on their individual estimated race time. Before, and 1 h after the cessation of the exercise, participants in underwear were weighed to the nearest 0.1 kg with a digital scale (Seca, Hamburg, Germany). Cardiovascular variables, including heart rate (HR), systolic (SAP) and diastolic (DAP) arterial blood pressures, were then measured continuously (Portapres ® ; Finapres Medical System, Amsterdam, The Netherlands) over a 10-min period while the participants lay in the supine position. Additionally, R-R intervals were measured continuously using a Polar RS800CX HR monitor (Polar, Kempele, Finland). Resting data were used to obtain spontaneous changes

including heart rate (HR), systolic (SAP) and diastolic (DAP) arterial blood pressures, were then measured continuously (Portapres ® ; Finapres Medical System, Amsterdam, The Netherlands) over a 10-min period while the participants lay in the supine position. Additionally, R-R intervals were measured continuously using a Polar RS800CX HR monitor (Polar, Kempele, Finland). Resting data were used to obtain spontaneous changes in arterial blood pressure, R-R interval and baseline steady-state hemodynamics. Cardiovascular parameters were also collected during repeated squat-stand maneuvers (Squat Stand Test, SST) performed for 5 min with a duty cycle of a squat held for 10 s followed by 10 s standing [31]. During SST, the participants were instructed to avoid performing a Valsalva maneuver while standing up.

Int. J. Environ. Res. Public Health2020,17, 6337 4 of 13 2.3. Heart Rate Variability, Barore ex Sensitivity and Hemodynamic Assessment The Portapres ® device measures arterial pressure using photoplethysmography of the middle phalanx of the middle nger, which is calibrated to the oscillometrically obtained brachial BP. Arterial pulse pressure (PP, mmHg) was calculated by subtracting DAP from SAP. The HR/Inter-Beat Interval (IBI) was derived from the beat-to-beat arterial pressure wave. The arterial pressure signal was then analyzed using Beatscope Software (TNO-TPD, Biomedical Instrumentation) to estimate other cardiovascular variables. Stroke volume (SV) was estimated using the Model ow method [33,34], and cardiac output (CO) was calculated as the product of HR and SV, whilst total peripheral resistance (TPR) was determined by dividing the mean arterial BP (MAP) by the CO. Additionally, arterial pressure was measured in the right arm by an electro-sphygmomanometer (Omron Healthcare, Kyoto, Japan) to corroborate the BP measurements from the Portapres ® device. IBI and SAP values extracted from Portapres ® device were used for subsequent barore ex sensitivity (BRS) analysis [31]. 2.4. Data Analysis Mean values of BP (SAP, DAP and MAP), other hemodynamic variables (SV, CO and TPR) and BRS and HRV indexes were calculated from the last 5 min of the 10-min period during supine rest and from the entire 5 min of the squat stand test (SST). Beat-by-beat SAP and IBI values were used to assess cardiac barore ex sensitivity (BRS). SAP and IBI data were linearly interpolated and resampled at 2 Hz for spectral and transfer function analysis (TF). Under resting conditions, TF of gain, phase and coherence between spontaneous oscillations in SAP and IBI were calculated in accordance with the work of Zhang et al. [35], i.e., 0.05–0.15 Hz for the low frequency (LF) range. During SST (performed at 0.05 Hz) TF gain, phase and coherence were calculated across a speci c frequency (SF) range (i.e., 0.031–0.078 Hz). Cardiac BRS was also assessed with the sequence method [36]. The sequence method is based on the identi cation of at least three consecutive beats (sequence) in which a de ned increase (or decrease)

frequency (LF) range. During SST (performed at 0.05 Hz) TF gain, phase and coherence were calculated across a speci c frequency (SF) range (i.e., 0.031–0.078 Hz). Cardiac BRS was also assessed with the sequence method [36]. The sequence method is based on the identi cation of at least three consecutive beats (sequence) in which a de ned increase (or decrease) in SAP is followed by a de ned increase (or decrease) in the IBI. Only sequences with a minimum correlation coe cient of 0.85 were accepted. Positive and negative sequences were averaged to obtain a representative value of cardiac barore ex sensitivity (BRSseq). To better represent BP control in the increasing and decreasing directions, mean gain values of positive (BRSSeq+) and negative (BRSSeq ) sequences were also computed separately. As described and independently, R–R intervals obtained using the Polar RS800CX heart rate monitor were uploaded to the Polar Precision Performance software (Polar, Kempele, Finland) and then exported as text les. HRV analysis was performed using Kubios HRV software (Version 2.1, Biosignal Analysis and Medical Imaging Group, Kuopio, Finland [37]). Signal artifacts were ltered by means of a moderate error correction lter. All the time series of R–R intervals showed low noise (identi ed errors<5%). As the physiological signi cance of several HRV indexes is still disputed [38], only indexes of parasympathetic modulation were calculated in the time domain (square root of the sum of successive di erences between adjacent normal R–R intervals squared; RMSSD) and in the frequency-domain high-frequency spectral power (HF, 0.15–0.4 Hz), calculated by Fast Fourier Transform (FFT) [39]. The respiratory rate was neither controlled nor recorded. However, on an individual basis, we systematically checked that the respiratory sinus arrythmia peak fell within the HF band. All recordings were consistent in this regard. 2.5. Statistical Analysis Data are presented as mean SD. The normal distribution of the data was veri ed with the Shapiro–Wilk test. If data were not normally distributed, natural logarithm transformation (Ln) was applied to obtain a normal distribution and to allow parametric statistical comparisons. All the variables were normally distributed after this procedure. Two-tailed

were consistent in this regard. 2.5. Statistical Analysis Data are presented as mean SD. The normal distribution of the data was veri ed with the Shapiro–Wilk test. If data were not normally distributed, natural logarithm transformation (Ln) was applied to obtain a normal distribution and to allow parametric statistical comparisons. All the variables were normally distributed after this procedure. Two-tailed unpaired t-tests were used to

Int. J. Environ. Res. Public Health2020,17, 6337 5 of 13 compare running times during the run between the two groups. A two-way (time (pre vs. post) group (men vs. women)) repeated measures analysis of variance (ANOVA) followed by Holm–Sidak post hoc analyses was performed to assess the e ects of run and group on all other variables. Ap-value of<0.05 was considered statistically signi cant. 3. Results The height (p<0.001) and weight (p<0.001) of women (164.8 6.1 cm and 58.2 7.5 kg, respectively) were signi cantly reduced compared to men (178.3 6.7 cm and 75.0 8.3 kg, respectively). Both women and men were normal-weight according to their body mass index values, the values being, nevertheless, signi cantly higher in women than in men (21.4 1.8 vs. 23.6 2.3 kg m 2 for women and men, respectively,p=0.012). No signi cant di erence in age (p=0.110) was observed (39.1 9.3 and 45.7 10.5 years for women and men, respectively). The . V O2max (p=0.018) and MAS (p=0.034) of women (46.8 6.8 mL kg 1 min 1 and 13.7 2.2 km h 1 , respectively) were signi cantly lower than for men (51.3 8.5 mL kg 1 min 1 and 15.8 2.2 km h 1 , respectively). The speeds associated with VT1 (p=0.049) and VT2 (p=0.041) were signi cantly lower for women (10.6 1.5 and 11.8 1.8 km h 1 , respectively) than for men (11.7 1.2 and 13.4 1.5 km h 1 , respectively). Hemodynamic variables and indexes of ANS function during supine rest are presented in Figure (bottom) and Table. Before the run, women exhibited a signi cantly lower SAP, MAP, CO and SV compared to men, whilst other hemodynamic variables were not di erent (i.e., HR and TPR). They also exhibited signi cantly higher Ln-RMSSD, Ln-HF and HFnu, as well as signi cantly lower coherence-LF from transfer function analysis.Int. J. Environ. Res. Public Health 2020, 17, x 5 of 13 The height (p < 0.001) and weight (p < 0.001) of women (164.8 ± 6.1 cm and 58.2 ± 7.5 kg, respectively) were significantly reduced compared to men (178.3 ± 6.7

Study compares cardiovascular responses in trained women and men post half-marathon.